ORIGINAL Ervin ARTICLE and Dye
Associations Between Posterior Functional Contacts and Nutrient Intakes and Serum Nutrient Values Among Adults in NHANES 2003–2004 R. Bethene Ervina/Bruce A. Dyeb
Purpose: To examine the associations between the numbers of posterior functional contacts (FCs) and selected nutrient intakes and serum/plasma nutrient values in 3,554 adults 25 years of age and older from the 2003–2004 National Health and Nutrition Examination Survey (NHANES). Materials and Methods: FCs consist of the number of zones of contact between the maxillary and opposing mandibular posterior teeth when the maxillary and mandibular posterior teeth are together. There were 16 possible zones of contact. Nutrient intakes were calculated from one 24-h dietary recall and selected nutritional biochemistries were measured. Multivariate linear regression was used to examine the association between the numbers of FCs and nutrient intakes or serum/plasma nutrient values, controlling for potential confounding variables. Results: Males with 6 or more FCs had higher vitamin A (p < 0.05), C (p < 0.05), E (p < 0.01) and B-6 intakes (p < 0.05) than those with 5 or fewer FCs. Females with 6 or more FCs had higher dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate intakes (p < 0.05) than those with 5 or fewer FCs. Males and females with 6 or more FCs had higher serum `-carotene than those with 5 or fewer FCs (p < 0.05 and p < 0.001, respectively). Males with 6 or more FCs had higher serum folate levels than those with 5 or fewer FCs (p < 0.01), and females with 6 or more FCs had higher serum vitamin C levels than those with 5 or fewer FCs (p < 0.05). Conclusions: Dietary intakes and serum levels of certain nutrients differ by the number of FCs present. Key words: dietary recall, functional contacts, NHANES, serum nutrients Oral Health Prev Dent 2014;12:265-276 doi: 10.3290/j.ohpd.a31666
D
entate status is an important factor affecting dietary intake and nutritional status. Adults who are edentulous or have fewer natural teeth are less likely to eat certain fruits and vegetables and have lower intakes of energy, protein, carotenes, vitamins A and C, folate and B vitamins, calcium, iron, zinc and dietary fiber (Joshipura et al, 1996; Sheiham and Steele, 2001; Marshall et al, 2002; Nowjacka
Nutritional Epidemiologist, Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Health and Nutrition Examination Statistics, Hyattsville, MD, USA.
b
Dental Epidemiology Officer, Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Health Examination Statistics, Hyattsville, MD, USA.
Correspondence: Bruce A. Dye, National Center for Health Statistics, Division of Health Examination Statistics, 3311 Toledo Rd, Room 4416, Hyattsville, MD 20782, USA. Tel: +1-301-458- 4199, Fax:+1-301-458-4029. Email: [email protected]
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Submitted for publication: 07.06.12; accepted for publication: 02.03.13
Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007; Ervin and Dye, 2009). They eat a less varied diet and have a lower overall diet quality (Marshall et al, 2002; Sahyoun et al, 2003). In addition, serum levels for some nutrients are lower among those with a compromised dentition (Sheiham and Steele, 2001; Nowjack-Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007). Another approach used to examine the association between dietary intake and dentition is to look at functional tooth units. A functional unit (FU), also known as a functional contact, is defined as any pair of opposing natural or prosthetic teeth (Hildebrand et al, 1995). Hildebrand et al (1997) assert that research that focuses only on the number of teeth present in a person’s mouth may give an overestimation of a person’s chewing potential be-
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cause it does not take into account the functional arrangement of the teeth. In contrast, FU measures take into account the basic functional interaction between upper and lower teeth and the number and type of teeth. Consequently, FUs are more discriminatory and descriptive of chewing and swallowing difficulties and food avoidances than merely counting the number of teeth present or identifying the percentage of subjects who are edentulous. The use of FUs and the analogous occluding pairs in dental research has been limited and not consistent. For example, Morita et al (2007) categorised posterior occlusal pairs (POP) for analysis as zero POPs, 1 to 3 POPs and 4 to 12 POPs; in contrast, de Andrade et al (2009) and Sheiham and Steele (2001) used zero POPs, 1 to 4 POPs and 5 to 8 POPs in research that scored one contact per occluding dental pair for a total of four possible pairs for each side of the mouth. These researchers only looked at natural teeth, whereas Sahyoun et al (2003) included a category for full dentures. None of these studies included third molar pairings. A limited amount of research has been conducted on the relationships between FUs and food and nutrient intakes. This research has used the threecategory POPs in the zero to 8 range. In general, those with no pairs of posterior teeth or fewer pairs of teeth had lower intakes of kilocalories, protein, dietary fiber, calcium, iron, phosphorus, B-vitamins, carotenes and vitamins A, C and E than those with 5 to 8 pairs of teeth (Sheiham and Steele, 2001; Sahyoun et al, 2003; de Andrade et al, 2009). Older adults who wore dentures or had less than five POPS had lower overall diet quality and may consume a less varied diet (Sheiham and Steele, 2001; Sahyoun et al, 2003). Some of these researchers have also looked at the relationships between FUs and serum nutrients and reported that blood levels of vitamin C and beta carotene were significantly and positively associated with number of pairs of posterior teeth (Sheiham and Steele, 2001; Sahyoun et al, 2003). As described earlier, none of these studies looked at FUs that included third molar pairings. In addition, none of them looked at males and females separately. It has been shown that males and females differ in their food choices, energy and nutrient intakes as well as overall diet quality (Federation of American Societies for Experimental Biology, 1995; Bates et al, 1999; Baker and Wardle, 2003; U.S. Department of Agriculture, 2007). In our previous research, we found differences in food and nutrient intakes by
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number and type of teeth present, and these differences varied by sex (Ervin and Dye, 2009; Ervin and Dye, 2011). The purpose of this study was to examine the associations between the number of posterior functional contacts, including third molar pairings, and selected nutrient intakes and serum nutrient values among adults in the National Health and Nutrition Examination Survey (NHANES) 2003–2004. The hypothesis tested was that nutrient intakes and serum nutrient values are positively associated with the number of functional contacts and the significant associations are different for males vs females.
MATERIALS AND METHODS NHANES is a cross-sectional nationally representative health and nutrition examination survey conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention. The survey design is a complex, stratified, multistage probability sample of the civilian, noninstitutionalised US population. NHANES 2003– 2004 included oversamples of low-income persons, adolescents 12–19 years old, persons 60 years of age and older, African Americans and Mexican Americans. The survey includes an interview administered in the home and a subsequent health examination performed at a mobile examination center (MEC). Trained interviewers conducted the interviews. Trained dentists performed the oral health examinations at the MEC and the overall quality of the dentate status data was considered to be excellent (Dye et al, 2007; Dye et al, 2008). Additional details about this survey can be found at: http://www. cdc.gov/nchs/about/major/nhanes/datalink.htm.
Sample population The examination of functional occlusal contacts was performed only on adults ≥ 25 years of age. A total of 6,308 adults, 25 years of age and over, were eligible to participate in NHANES 2003–2004. Of the eligible sample, 4,568 adults (72%) 25 years of age and over participated in the household interview. Approximately 94% (4,284) of the household interview sample also participated in the MEC exam. Only those adults who participated in both the household interview and the MEC exam were included in the analytic sample (4,284).
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Participants were excluded from this sample if their dietary recall was not complete and reliable (261), any of the laboratory measures were missing (273), the functional contacts information was incomplete or missing (190), their response to the dietary supplement use question was missing (6) or their responses to the levels of education or smoking questions were missing (7). The final analytic sample consisted of 3,547 adults ≥ 25 years of age.
Predictor and confounding variables The analysis was based on the number of posterior functional contacts (FCs) which consists of the number of posterior occluding pairs (POPs) of teeth (premolars and molars, including third molars). The NHANES functional contact assessment required the examiner to evaluate the relationship between the maxillary posterior teeth to the opposing mandibular posterior teeth after the participant had closed their maxillary and mandibular posterior teeth together into a normal, static position. There were 8 possible zones of contact in the posterior region for each of the left and right areas of the mouth. The premolars were counted as a single zone and the molars were counted as two zones each. Contacts between two natural teeth, two denture teeth or a combination of natural and denture teeth were counted as a functional contact for this study, while the absence of POPs was counted as no FC. The maximum number of posterior contacts was 16. The FCs were treated as discrete variables in the regression analyses. We grouped functional contacts into four categories for the first set of analyses. These categories consisted of no FC, 1 to 5 FCs, 6 to 11 FCs and 12 to 16 FCs, including information from the third molars. The upper break point was based on results from the preliminary screening which revealed a break in nutrient intakes between 11 and 12 contacts. The lower break point was set at five to be consistent with other work currently being conducted on functional contacts (Dye and Steele, personal communication). In the second set of analyses, the four catgeories of contacts were collapsed to two more comprehensive categories: 5 or fewer FCs vs 6 or more FCs. Our previous analyses have revealed that age, race/ethnicity, education and smoking status were usually significantly associated with the nutrient intakes (Ervin and Dye, 2009; Ervin and Dye, 2011).
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Other researchers have controlled for some if not all of these variables (Joshipura et al, 1996; Sheiham and Steele, 2001; Nowjack-Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007). These variables were treated as potential confounding variables and were defined as follows in the present analyses. Since only adults 25 years and older received the functional contacts examination, age was categorised into 3 groups: 25–39 years old, 40–59 years old and 60 years of age or over. Race/ethnicity consisted of non-Hispanic Whites, non-Hispanic Blacks, Mexican Americans and all other race and ethnic groups. Education was also categorised into three groups: less than high school (HS), high school diploma including a General Education Development high school equivalency degree (GED), or more than high school. The smoking status variable was based on cigarette smoking only. Participants who never smoked or smoked less than 100 cigarettes in their lifetime were labeled ‘never smokers’; participants who smoked at least 100 cigarettes in their lifetime, but were not currently smoking were labeled ‘former smokers’; and participants who had smoked at least 100 cigarettes in their lifetime and currently smoked some days or everyday were labeled ‘current smokers.’ Dietary supplement use was included as a confounding variable when the response variables were serum/plasma nutrient values. During the NHANES 2003–2004, questions about dietary supplement use were asked only during the household interview which may have taken place several weeks before the MEC exam where blood samples were collected. Because of this time lag, it is possible that serum/plasma nutrient values may not reflect recent supplement use especially if the participant changed their pattern of supplement intake prior to the MEC exam.
Response variables Trained interviewers conducted dietary recall interviews using an automated data collection system during the MEC examination. Detailed descriptions of the 2003–2004 dietary interview and data processing procedures can be found under the dietary interview components at http://www.cdc.gov/ nchs/nhanes/nhanes2003–2004/exam03_04. htm. Although two dietary recalls were collected about 3 to 10 days apart, only the first day’s (day 1) recall was used in these analyses. The intent was to examine usual intakes of the FC categories
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rather than estimating usual intakes of individuals, and more participants completed the day-1 recall than both recalls. Nutrient intakes were calculated from the 24-h dietary recalls. Since only the impact of the number of occlusal contacts on nutrient intakes from food was of interest, nutrient intakes from dietary supplements were not calculated in these analyses. Kilocalories, protein, dietary fiber, alpha- and `-carotene, vitamins A, C, E and B-6 and total folate were analysed. Trained phlebotomists performed the blood collections during the MEC examination. Detailed descriptions of the laboratory procedures can be found under the 2003–2004 laboratory files at h t t p : // w w w . c d c . g o v / n c h s / n h a n e s / nhanes2003–2004/lab03_04.htm. The following nutritional biochemistries were examined: serum retinol (ug/dL), serum `-carotene (ug/dL), serum vitamin C (mg/dL), serum _-tocopherol (mg/dL), plasma vitamin B-6 (nmol/L) and serum folate (ng/mL).
Statistical tests Data were analysed using SAS for Windows (release 9.2; SAS Institute; Cary, NC, USA) and SUDAAN (release 10.0; Research Triangle Institute; Research Triangle Park, NC, USA). Day-1 dietary sample weights were used. Since day-1 dietary recall data were used in the analyses, sample weights specially created for the day-1 recalls were used (see the analytic notes for the day 1 dietary interview – total nutrient intakes; http://www.cdc.gov/ nchs/data/nhanes/nhanes_03_04/dr1tot_c.pdf). Sample weights were employed that incorporated the differential probabilities of selection and included adjustments for oversampling of certain populations and non-response to the household interview and MEC examination. The percentage distributions and standard errors were calculated for the confounding and predictor variables by sex. Multivariate linear regression models were run to examine the association between the FC variables and dietary nutrient intakes and serum/plasma nutrient values, with control for the potential confounding variables. In addition, we controlled for caloric intake in all of the models examining nutrient intakes, since nutrient intake is often positively correlated with caloric intake (Willett and Stampfer, 1998), and dietary supplement use in all of the models examining serum/plasma nutrient values. Least squares means (LSM) were also compared
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to determine whether significant differences existed in intakes or blood levels among the FC categories. When the four FC categories were examined, the no-FC, 1- to 5-FCs and 6- to 11-FCs categories were compared to the 12- to 16-FCs category (reference). When the two more comprehensive FC groups were examined, we compared the intakes or blood levels of the 5 or fewer FCs group to those of the 6 or more FCs group. Separate multivariate linear regression models were constructed for each sex. Nutrient values were transformed using a log10 transformation prior to regression analyses for those nutrients that deviated substantially from normality. Since zero cannot be log-transformed, when a nutrient intake was zero, a small value greater than zero but less than the lowest intake reported for that nutrient was added to all of the intakes. The antilogs of the least squares means and standard errors from the regression analyses are reported in the tables. A Satterthwaite-adjusted F-statistic was employed to test whether the FC variable was significantly associated with nutrient intakes or serum/ plasma nutrient values. When there was a significant association, a Satterthwaite-adjusted F-statistic was used to determine which FC categories were significantly different from the reference category (12 or more FCs). The critical value was set at p < 0.05. For nutrients that were transformed, the significance tests were based on the log-transformed values.
RESULTS Table 1 presents the weighted distribution for selected characteristics of the analytic sample. The sample was nearly equally distributed between males (49%) and females (51%) and included primarily non-Hispanic white persons (75% for males and 76% for females). More males than females were in the 25–39- and 40–59-year-old age groups, but the opposite pattern was true for participants who were ≥ 60 years of age. A little more than onefourth of the sample had a high school or highschool equivalency degree (26%), while 56% had more than a high-school education. A larger proportion of males than females were current or former smokers (61% males vs 46% females). About half of the males (51%) reported taking supplements in the past 30 days, but nearly two-thirds of the females (63%) reported taking supplements during that interval. Most adults (83%) had six or more FCs.
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Nutrient intakes Table 2 presents results for the association between the four-category classification of functional contacts and nutrient intakes. Among males, FCs were significantly associated with caloric intake (p < 0.05) and vitamin E (p < 0.05). The groups with zero contacts (p < 0.01) and 6 to 11 FCs (p < 0.05) had significantly lower caloric intakes than the reference group (12 to 16 FCs). The zero-FC (p < 0.001), 1- to 5-FCs (p < 0.005) and 6- to 11-FCs (p < 0.05) categories all had significantly lower vitamin E intakes than the reference group. Among females, FCs were significantly associated with dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate (p < 0.05) intakes. All three groups had lower dietary fiber and vitamin E intakes than that of the reference group. The p-values were less than 0.05 for each comparison to the reference category for dietary fiber. The p-values for each comparison for vitamin E were p < 0.005 for 0 contacts, p < 0.05 for 1 to 5 contacts and p < 0.05 for 6 to 11 contacts. The groups with zero contacts and 1 to 5 contacts had lower folate intakes than the reference group (p < 0.05 for each comparison). None of the other nutrients were significantly associated with functional contacts for males or females. A few more nutrients were significantly associated with FCs in males when the contacts were categorised as being above or below a threshold of 5 contacts (Table 3). Males with more than 5 contacts had significantly higher vitamin A (p < 0.05), C (p < 0.05), E (p < 0.01) and B-6 intakes (p < 0.05) than those with 5 or fewer contacts. For females, the same three nutrients that were significant when 4 FC categories were used were also significant when 2 categories were used. Females with more than 5 contacts had significantly higher dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate intakes (p < 0.05) than those with 5 or fewer contacts. None of the other nutrients were significantly associated with FCs for males or females.
Table 1 Weighted distribution of characteristics among survey participants by sex, NHANES 2003–2004
Characteristics
Males (n = 1,749)
Females (n = 1,798)
% (SE)
% (SE)
Age 25–39 years
32.2 (1.5)
29.9 (1.9)
40–59 years
42.8 (1.4)
40.8 (2.0)
60 years and older
24.9 (0.9)
29.3 (1.3)
Non-Hispanic white
75.4 (3.3)
75.7 (3.4)
Non-Hispanic black
9.3 (1.6)
10.5 (1.9)
Mexican American
7.6 (2.2)
6.0 (1.7)
Other
7.7 (1.1)
7.8 (1.0)
Less than high school
17.2 (1.4)
17.9 (1.9)
High school or GED*
26.2 (1.7)
26.0 (1.3)
Greater than high school
56.6 (2.2)
56.1 (2.4)
Never
38.5 (1.6)
54.4 (1.4)
Former
32.8 (1.4)
24.4 (1.5)
Current
28.6 (1.4)
21.2 (1.5)
Yes
50.6 (1.6)
63.0 (1.8)
No
49.4 (1.6)
37.0 (1.8)
No FCs
5.4 (1.0)
4.0 (0.5)
1–5 FCs
11.4 (1.3)
12.6 (1.7)
6–11 FCs
38.2 (1.7)
38.1 (1.0)
12–16 FCs
45.0 (1.7)
45.3 (2.2)
Race and ethnicity
Education
Smoking status
Use of dietary supplements
Functional Contacts †
* GED is a General Education Development high-school equivalency degree. † Functional contacts were defined as the number of posterior occluding pairs (POPs) of teeth (premolars and molars, including third molars).
Serum/plasma nutrients Serum/plasma nutrients were also examined based on the four- and two-category FC groups. Serum`-carotene levels were significantly associated with functional contacts for both males and females regardless of whether four categories
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(Table 4) (males: p < 0.05; females: p < 0.01) or two categories were used (Table 5) (p-values reported below with each comparison). Males with zero contacts or 1 to 5 contacts had lower serum `-carotene levels than the reference group (p < 0.001 and p < 0.05, respectively) and males
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Table 2 Associations between FCs in four categories and nutrient intakes for adults ≥ 25 years of age adjusted for confounding variables: United States, 2003–2004* Males Nutrient
p-value for relationship†
Kilocalories (kcal)
< 0.050
LSM (SE)‡
Females p-value for pairwise comparisons¶
p-value for relationship†
LSM (SE)‡
p-value for pairwise comparisons¶
0.505
0 contacts
2224 (135)
< 0.010
1862 (76)
0.885
1–5 contacts
2507 (71)
0.061
1812 (77)
0.573
2530 (51)
< 0.050
1794 (43)
0.264
2687 (52)
•
1875 (40)
•
6–11 contacts §
12–16 contacts Protein (g)
0.486
0.393
0 contacts
95 (2)
0.163
65 (5)
0.589
1–5 contacts
97 (3)
0.530
66 (2)
0.353
6–11 contacts
97 (1)
0.295
69 (1)
0.406
12–16 contacts§
99 (2)
•
68 (1)
•
Dietary fiber (g)
0.190
< 0.050
0 contacts
17.2 (0.9)
0.258
12.2 (0.6)
< 0.050
1–5 contacts
17.6 (0.9)
0.462
13.0 (0.3)
< 0.050
16.9 (0.5)
0.084
13.3 (0.2)
< 0.050
18.4 (0.6)
•
14.6 (0.5)
•
0.182
6–11 contacts §
12–16 contacts
††
Vitamin A, RAE (μg)
0.194
0.280
0 contacts
338 (1.2) ‡‡
0.050
327 (1.2)‡‡
1–5 contacts
422 (1.1)
0.132
362 (1.1)
< 0.050
6–11 contacts
440 (1.1)
0.392
386 (1.0)
0.368
12–16 contacts§
479 (1.0)
•
413 (1.0)
•
††
_-carotene (μg)
0.555
0.396
0 contacts
21.2 (1.7) ‡‡
0.346
17.5 (1.3)‡‡
1–5 contacts
25.3 (1.4)
0.234
33.9 (1.2)
0.875
34.0 (1.2)
0.656
34.0 (1.2)
0.847
36.9 (1.1)
•
35.4 (1.2)
•
6–11 contacts §
12–16 contacts
††
`-carotene (μg)
0.154
< 0.050
0.341
0 contacts
490 (1.3) ‡‡
0.073
522 (1.2)‡‡
0.097
1–5 contacts
649 (1.1)
< 0.050
640 (1.1)
0.114
6–11 contacts
701 (1.1)
0.172
713 (1.1)
0.717
12–16 contacts§
851 (1.1)
•
741 (1.1)
††
Vitamin C (mg)
270
0.098
0.897
0 contacts
35.5 (1.2) ‡‡
0.108
43.5 (1.1)‡‡
0.810
1–5 contacts
36.9 (1.1)
< 0.050
44.0 (1.1)
0.865
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6–11 contacts §
12–16 contacts
Vitamin E as _-tocopherol equivalents (mg)††
51.3 (1.1)
0.672
43.1 (1.1)
0.649
53.8 (1.1)
•
45.0 (1.1)
•
< 0.050
< 0.050
0 contacts
5.2 (1.1)‡‡
< 0.001
4.2 (1.1)‡‡
< 0.005
1–5 contacts
5.8 (1.0)
< 0.005
4.8 (1.0)
< 0.050
6.0 (1.1)
< 0.050
4.9 (1.0)
< 0.050
6.9 (1.0)
•
5.4 (1.0)
•
6–11 contacts §
12–16 contacts
Vitamin B-6 (mg)††
0.275
0.488
0 contacts
1.7 (1.1)‡‡
0.098
1–5 contacts
1.7 (1.0)
0.075
1.3 (1.1)‡‡
0.414
6–11 contacts
1.8 (1.1)
0.350
1.3 (1.0)
0.786
12–16 contacts§
2.0 (1.0)
•
1.4 (1.0)
•
††
0.216
Folate (μg)
0 contacts
1–5 contacts 6–11 contacts §
12–16 contacts
< 0.050
0.052
260 (1.0)‡‡
< 0.050
376 (1.0)
0.081
277 (1.0)
< 0.050
378 (1.1)
0.252
299 (1.0)
0.112
411 (1.0)
•
310 (1.0)
•
344 (1.1)
‡‡
¶¶
* Confounding variables in model: age group, race/ethnicity, education and smoking status. When the outcome variable was nutrient intake kilocalories were included in the model. † F-test to establish whether there is a relationship between the FC variable and nutrient intakes, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ‡ LSM = Least Squares Means; SE = Standard error. ¶ F-test for pairwise comparisons of 0 contacts, 1–5 contacts, and 6–11 contacts to the reference category, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. § Reference category. †† Nutrient values were transformed using a log10 transformation prior to regression analyses; all statistical tests were conducted using the log transformed values. ‡‡ All values shown are the antilog of the log10 values for least squares means and standard errors from the linear regression. All estimates shown were statistically reliable as the log-transformed values unless otherwise noted. ¶¶ Estimate does not meet the standard of reliability and precision.
with ≤ 5 FCs had lower serum levels than those with > 5 FCs (p < 0.05). Females with zero contacts or 1 to 5 contacts had lower serum `-carotene levels than the reference group (p < 0.005 and p < 0.001, respectively) and those with ≤ 5 FCs had lower serum levels than those > 5 FCs (p < 0.001). Serum _-tocopherol was significantly associated with FCs when classified into four categories for males (p < 0.05). Those with zero contacts had lower serum levels than those with 12 or more contacts (p < 0.001). Males with ≤ 5 or fewer contacts had lower serum folate levels than those with > 5 contacts (p < 0.01) and females with ≤ 5 or fewer contacts had lower serum vitamin C levels than those with > 5 contacts (p < 0.05). None of the other serum or plasma nutrients were significantly associated with FCs for males or females.
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DISCUSSION In this study, we demonstrated that there were positive associations between the number of posterior functional contacts and some nutrient intakes, but the patterns varied by gender and by the scheme used for categorising the number of contacts. When four categories were considered, males with 12 or more contacts (reference group) consumed more vitamin E than any of the other FC levels and more calories than those with zero contacts or 6 to 11 contacts. Females with 12 or more contacts had higher dietary fiber and vitamin E intakes than any of the other FC categories and higher folate intakes than those with 5 or fewer contacts. When the categories were collapsed into two more comprehensive FC groups, males who had more than 5 contacts had higher vitamin A, B-6 and C intakes
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Table 3 Associations between 5 or less vs more than 5 FCs and nutrient intakes for adults ≥ 25 years of age adjusted for confounding variables: United States, 2003–2004* Males Nutrient
Females
†
LSM (SE)
p-value
≤ 5 contacts
2430 (76)
0.070
> 5 contacts
2612 (38)
‡
†
LSM (SE)
p-value‡
1828 (56)
0.898
Kilocalories (kcal)
1837 (23)
Protein (gm) ≤ 5 contacts
97 (2)
0.599
65 (2)
0.149
> 5 contacts
98 (1)
69 (1)
18 (0.8)
0.910
13 (0.3)
< 0.050
18 (0.4)
14 (0.4)
≤ 5 contacts
397 (1.1)§
< 0.050
355 (1.1)§
0.052
> 5 contacts
459 (1.0)
400 (1.0)
_-carotene (μg)¶
≤ 5 contacts
24.1 (1.3)§
0.211
29.3 (1.2)§
0.438
> 5 contacts
35.5 (1.1)
34.7 (1.1)
≤ 5 contacts
604 (1.1)§
0.057
612 (1.1)§
0.095
> 5 contacts
776 (1.0)
728 (1.1)
≤ 5 contacts
36.6 (1.1)§
< 0.050
44.0 (1.1)§
0.977
> 5 contacts
52.6 (1.1)
44.1 (1.1)
≤ 5 contacts
5.6 (1.0)§
< 0.010
4.7 (1.0)§
< 0.050
> 5 contacts
6.4 (1.0)
5.1 (1.0)
≤ 5 contacts
1.7 (1.0)§
< 0.050
1.3 (1.1)§
0.177
> 5 contacts
1.9 (1.0)
1.3 (1.0)
Dietary fiber (g) ≤ 5 contacts > 5 contacts Vitamin A, RAE (μg)
¶
`-carotene (μg)¶
Vitamin C (mg)¶
Vitamin E as _-tocopherol equivalents (mg)¶
Vitamin B-6 (mg)¶
Folate (μg)¶ ≤ 5 contacts
368 (1.0)§
0.078
274 (1.0)§
< 0.050
> 5 contacts
395 (1.0)
304 (1.0)
* Confounding variables in model: age group, race/ethnicity, education, and smoking status. When the outcome variable was nutrient intake kilocalories were included in the model. † LSM = Least Squares Means; SE = Standard error. ‡ F-test to establish whether there is a relationship between the FCs variable and nutrient intakes, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ¶ Nutrient values were transformed using a log10 transformation prior to regression analyses; all statistical tests were conducted using the log transformed values. § All values shown are the antilog of the log10 values for least squares means and standard errors from the linear regression. All estimates shown were statistically reliable as the log-transformed values.
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Table 4 Associations between number of FCs in four categories and serum/plasma nutrient levels for selected nutrients for adults ≥ 25 years of age adjusting for confounding variables in the models: United States, 2003–2004* Males Nutrient†
p-value for relationship‡
Retinol (ug/dL)
0.456
Females
¶
LSM (SE)
p-value for pairwise comparisons§
p-value for relationship‡
LSM (SE)
p-value for pairwise comparisons§
¶
0.348
0 contacts
65.0 (2.0)
0.852
61.1 (2.4)
0.079
1–5 contacts
63.1 (2.0)
0.227
55.8 (1.1)
0.207
64.2 (0.6)
0.163
57.4 (1.1)
0.856
65.4 (0.6)
•
57.2 (0.8)
•
6–11 contacts ††
12–16 contacts
`-carotene (ug/dl)
< 0.050
< 0.010
0 contacts
9.0 (1.1)
< 0.001
14.9 (1.3)
< 0.005
1–5 contacts
13.1 (1.6)
< 0.050
16.2 (1.3)
< 0.001
14.9 (0.9)
0.054
20.7 (1.5)
0.106
17.6 (1.0)
•
23.6 (1.3)
•
6–11 contacts ††
12–16 contacts
Vitamin C (mg/dl)
0.110
0.064
0 contacts
0.70 (0.06)
< 0.010
0.85 (0.06)
< 0.010
1–5 contacts
0.85 (0.06)
0.541
0.99 (0.03)
0.179
6–11 contacts
0.91 (0.03)
0.711
1.03 (0.02)
0.252
12–16 contacts††
0.89 (0.03)
•
1.08 (0.04)
•
_-tocopherol (mg/dl)
< 0.050
0.362
0 contacts
1.18 (0.06)
< 0.001
1.31 (0.06)
< 0.010
1–5 contacts
1.42 (0.05)
0.927
1.51 (0.06)
0.836
1.41 (0.01)
0.712
1.48 (0.04)
0.860
1.43 (0.03)
•
1.49 (0.03)
•
6–11 contacts ††
12–16 contacts
Vitamin B-6 (nmol/l)
0.331
0.337
0 contacts
48.0 (5.2)
1–5 contacts
59.7 (3.5)
6–11 contacts
69.0 (8.1)
12–16 contacts††
64.2 (4.7)
Folate (ng/mL)
0.108
0.403 ‡‡
0 contacts
10.7 (1.0)
< 0.050
1–5 contacts
12.1 (0.8)
0.050
14.5 (0.6)
0.250
13.4 (0.3)
0.338
14.7 (0.4)
0.079
14.4 (0.8)
•
15.4 (0.3)
•
6–11 contacts ††
12–16 contacts
* Confounding variables in model: age group, race/ethnicity, education, smoking status and dietary supplement use. † Serum was used for retinol, `-carotene, vitamin C, _-tocopherol and folate; plasma was used for vitamin B-6. ‡ F-test to establish whether there is a relationship between the FCs variable and serum/plasma nutrients, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ¶ LSM = Least Squares Means; SE = Standard error. § F-test for pairwise comparisons of 0 contacts, 1–5 contacts, and 6–11 contacts to the reference category, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. †† Reference category. ‡‡ Estimate does not meet the standard of reliability and precision.
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Table 5 Associations between 5 or less vs more than 5 FCs and serum/plasma nutrient levels for selected nutrients for adults ≥ 25 years of age adjusting for confounding variables in the models: United States, 2003–2004* Males Nutrient†
Females
‡
LSM (SE)
p-value
≤ 5 contacts
63.7 (1.7)
0.487
> 5 contacts
64.9 (0.5)
`-carotene (ug/dl)
≤ 5 contacts
12.0 (1.2)
> 5 contacts
16.3 (0.7)
Vitamin C (mg/dl)
≤ 5 contacts
0.81 (0.04)
> 5 contacts
0.90 (0.02)
¶
‡
LSM (SE)
p-value¶
57.0 (1.3)
0.807
Retinol (ug/dl)
57.3 (0.6)
< 0.050
16.1 (1.0)
< 0.001
22.2 (1.2)
0.061
0.96 (0.03)
< 0.050
1.06 (0.03)
_-tocopherol (mg/dl) ≤ 5 contacts
1.35 (0.04)
> 5 contacts
1.42 (0.02)
0.094
1.46 (0.05)
0.645
1.49 (0.02)
Vitamin B-6 (nmol/l) ≤ 5 contacts
71.3 (10.0)
> 5 contacts
81.2 (3.4)
0.281
56.8 (3.2)
0.055
66.4 (4.9)
Folate (ng/ml) ≤ 5 contacts
11.7 (0.6)
> 5 contacts
13.9 (0.4)
< 0.010
17.9 (3.7)
0.454
15.1 (0.3)
* Confounding variables in model: age group, race/ethnicity, education, smoking status and dietary supplement use. † Serum was used for retinol, `-carotene, vitamin C, _-tocopherol and folate; plasma was used for vitamin B-6. ‡ LSM = Least Squares Means; SE = Standard error. ¶ p-value for association of FCs with serum/plasma nutrients, based on the Satterthwaite-adjusted F-statistic. The critical value was p< 0.05.
than those with 5 or fewer contacts. Females who had more than 5 contacts had higher dietary fiber, vitamin E and folate intakes than those with 5 or fewer contacts. Certain serum nutrients were also associated with the number of posterior FCs. Males with 12 or more contacts had higher serum _-tocopherol levels than those with zero posterior contacts. Five or fewer FCs appeared to represent a critical boundary for several nutrients. When the 4-category model was examined, those with 12 or more contacts had higher serum `-carotene levels than those with 5 or fewer teeth. When two FC categories were used, those with more than 5 contacts had higher serum `-carotene levels than those with 5 or fewer contacts. These patterns were true for males and females. In addition, males with more than 5 contacts had higher serum folate and females with
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more than 5 contacts had higher serum vitamin C than those with 5 or fewer contacts. One reason those with more FCs may have had higher intakes of these nutrients could be because they consumed more energy and foods. Increasing caloric intake could increase intakes of nutrients, but we controlled for calories in the nutrient analyses. Another possibility is that those with more FCs consumed more foods that were especially rich in dietary fiber, vitamins A, C, B-6, E or folate. Readyto-eat cereals are rich sources of dietary fiber, folate and vitamins A, C, E and B-6. Yeast breads and legumes are rich sources of folate and dietary fiber (Cotton et al, 2004; Maras et al, 2004; U.S. Department of Agriculture, 2009). Beginning in January 1998, Federal law required that all enriched cereal grains be fortified with folate. These foods include enriched bread, pasta, flour, breakfast ce-
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real and rice (Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, 1998). Dark green leafy vegetables and orange and grapefruit juices are excellent sources of folate and vitamin C, while dark green leafy vegetables and deep yellow or orange vegetables are excellent sources of vitamin A. Organ meats are rich sources of vitamins A and B-6 and nuts and seeds are rich sources of dietary fiber and vitamin E. Cooked cereals and dark green vegetables are also abundant sources of folate; vegetable margarine, oils and salad dressings are good sources of vitamin E; fruits and vegetables are excellent sources of dietary fiber and vitamin C; and dairy products are excellent sources of vitamin A (Cotton et al, 2004; Maras et al, 2004; U.S. Department of Agriculture, 2009). Finally, other factors not present in these models, such as diet and health knowledge, food preferences and income, might have contributed to some of these differences. For instance, those with more FCs might have had more diet and health knowledge and chosen foods richer in dietary fiber, vitamins A, C, B-6, E or folate. A few other studies have looked at nutrient intakes or serum/plasma nutrients in relationship to the number of pairs of occluding teeth in older adults. Depending on the study, older adults with zero posterior occlusal pairs (POPs) or fewer POPs had lower intakes of a broad range of nutrients including calories, protein, carbohydrate, dietary fiber, selected minerals, folacin, carotenes and vitamins A, C and E (Sheiham and Steele, 2001; Marshall et al, 2002; Sahyoun et al, 2003; de Andrade et al, 2009). They also had lower serum vitamin C and beta carotene levels (Sheiham and Steele, 2001; Sahyoun et al, 2003). None of these studies included younger and middle-age adults. These results are consistent with results from our earlier studies that examined only older adults (Ervin and Dye, 2009; Ervin and Dye, 2011). Results from the present study extend the evidence to include younger and middle-age adults. There may be a number of reasons why the results for serum nutrient values do not correspond with those from the 24-h recalls. Measurement of dietary intake is imprecise, one dietary recall does not reflect an individual’s usual intake and nutrient databases may be incomplete or imprecise (Dwyer, 1999). While plasma and serum levels of nutrients tend to reflect recent dietary intake, other factors may affect nutrient concentrations in biologic samples, including the intake of other nutrients, lifestyle factors, e.g. smoking or physical activity, use
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of oral contraceptive agents, genetic influences, fluctuations resulting from diurnal variation and meal consumption, medications, infection, inflammation and stress (Gibson, 1990; Hunter, 1998). Strong homeostatic controls may limit the interpretability of plasma or serum nutrient concentrations as a measure of dietary intake for some nutrients. For instance, in well-nourished populations, liver stores of vitamin A may be large enough to buffer serum levels over a wide range of dietary vitamin A intakes (Hunter, 1998). In other cases, homeostatic mechanisms maintain nearly normal plasma or serum nutrient concentrations in the presence of severe depletion of bodily stores (Gibson, 1990). Functional contacts may be a better indicator of the association between dentition status and dietary intake than total tooth count or other measures of impaired dentition status. In previous research, the present authors found that when total tooth count was treated as a continuous variable or collapsed into categories, only _- and `-carotene and vitamin C intakes were significantly associated with tooth count (Ervin and Dye, 2009; Ervin and Dye, 2011). In the current study, many more significant associations with nutrient intake were found when posterior FCs were used. Sahyoun et al (2003) also reported that the number of posterior pairs of teeth was more strongly associated with nutritional status in older adults than the total number of teeth or the number of posterior teeth. There are limitations to this study. These data were cross sectional in nature and causal associations thus cannot be established based on these results. Many comparisons were performed in this study, so there is a chance of having rejected a hypothesis that is actually true. Nonetheless, these results are generally consistent with that of other researchers.
CONCLUSION In conclusion, dietary intakes and serum levels of certain nutrients differ by the number of functional contacts present. Most of these nutrients can be found in a wide variety of foods, including ones that should not present chewing difficulties. Data from this study suggest that the dental and nutrition communities need to develop programmes to help adults with limited posterior functional contacts improve their intakes of dietary fiber, vitamins A, C, B-6 and E, `-carotene and folate. Although the
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study design used in this research is not sufficient to recommend changes based on the study findings, this study does suggests that from a US population perspective, functional contact replacement and rehabilitation to a status of 6 or more posterior functional contacts could potentially improve dietary intakes of key nutrients. Nevertheless, clinical dentists should not rely on these findings alone but also should consider other, individual factors in recommending posterior dental prostheses to replace lost functional contacts.
REFERENCES 1. Baker AH, Wardle J. Sex differences in fruit and vegetable intake in older adults. Appetite. 2003;40:269–275. 2. Bates CJ, Prentice A, Finch S. Gender differences in food and nutrient intakes and status indices from the National Diet and Nutrition Survey of People Ages 65 Years and Over. Eur J Clin Nutrition 1999;53:694–699. 3. Cotton PA, Subar AF, Friday JE, Cook A. Dietary sources of nutrients among US adults, 1994 to 1996. J Am Dietetic Assoc 2004:104:921–930. 4. de Andrade FB, de França Caldas A Jr, Kitoko PM. Relationship between oral health, nutrient intake and nutritional status in a sample of Brazilian elderly people. Gerodontology 2009;26:40–45. 5. Dwyer J. Dietary assessment. In: Shils ME, Olson JA, Shike M, Ross AC (eds). Modern Nutrition in Health and Disease, ed 9. Baltimore, MD: Williams & Wilkins, 1999: 937–959. 6. Dye BA, Barker LK, Selwitz RH, Lewis BG, Wu T, Fryar CD, Ostchega Y, BeltranED, Ley E. Overview and quality assurance for the National Health and Nutrition Examination Survey (NHANES) oral health component, 1999–2002. Community Dent Oral Epidemiol 2007;35:140–151. 7. Dye BA, Nowjack-Raymer R, Barker LK, Nunn JH, Steele JG, Tan S, Lewis BG, Beltran ED. Overview and quality assurance for the oral health component of the National Health and Nutrition Examination Survey (NHANES), 2003–2004. J Public Health Dent 2008; 68:218–226. 8. Ervin RB, Dye BA. The effect of functional dentition on healthy eating index scores and nutrient intakes in a nationally representative sample of older adults. J Public Health Dent 2009;69:207–216. 9. Ervin RB, Dye BA. Number of natural and prosthetic teeth impact nutrient intakes of older adults in the United States. Gerodontology 2011; doi: 10.1111/ j.17412358.2011.00546.x.
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10. Federation of American Societies for Experimental Biology. Life Sciences Research Office. Prepared for the Interagency Board for Nutrition Monitoring and Related Research. Food consumption and nutrient intake. In: Third Report on Nutrition Monitoring in the United States: Volume 1. Washington, DC: US Government Printing Office; 1995: 99–158. 11. Gibson RS. Laboratory assessment. In: Principles of Nutritional Assessment. New York, NY: Oxford University Press, 1990:285–306. 12. Hildebrandt GH, Loesche WJ, Lin C-F, Bretz WA. Comparison of the number and type of dental functional units in geriatric populations with diverse medical backgrounds. J Prosth Dent 1995;73:253–261. 13. Hildebrandt GH, Dominguez BL, Schork MA, Loesche WJ. Functional units, chewing, swallowing and food avoidance among the elderly. J Prosth Dent 1997;77:588–595. 14. Hunter D. Biochemical indicators of dietary intake. In: Willett W (ed). Nutritional Epidemiology, ed 2. New York, NY: Oxford University Press, 1998:174–243. 15. Joshipura KJ, Willett WC, Douglass CW. The impact of edentulousness on food and nutrient intake. J Am Dent Assoc 1996;127:459–467. 16. Maras JE, Bermudez OI, Qiao N, Bakun PJ, Boody-Alter EL, Tucker KL. Intake of _-tocopherol is limited among US adults. J Am Dietetic Assoc 2004:104:567–575. 17. Marshall TA, Warren JJ, Hand JS, Xie X-J, Stumbo PJ. Oral health, nutrient intake and dietary quality in the very old. J Amer Dent Assoc 2002;133:1369–1379. 18. Morita I, Nakagaki H, Kato K, Murakami T, Tsuboi S, Hayashizaki J, Sheiham A. Relationship between number of natural teeth in older Japanese people and health related functioning. J Oral Rehabil 2007;34:428–432. 19. Nowjack-Raymer RE, Sheiham A. Association of edentulism and diet and nutrition in US adults. J Dent Res 2003;82:123–126. 20. Nowjack-Raymer RE, Sheiham A. Numbers of natural teeth, diet, and nutritional status in US adults. J Dent Res 2007;86:1171–1175. 21. Sahyoun NR, Chien-Lung L, Krall E. Nutritional status of the older adult is associated with dentition status. J Am Dietetic Assoc 2003;103:61–66. 22. Sheiham A, Steele J. Does the condition of the mouth and teeth affect the ability to eat certain foods, nutrient and dietary intake and nutritional status amongst older people? Public Health Nutrition 2001;4:797–803. 23. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Food and Nutrition Board. Institute of Medicine. Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B-6, folate, vitamin B-12, pantothenic Acid, biotin, and choline. Washington, DC: National Academy Press, 1998.
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Associations Between Posterior Functional Contacts and Nutrient Intakes and Serum Nutrient Values Among Adults in NHANES 2003–2004 R. Bethene Ervina/Bruce A. Dyeb
Purpose: To examine the associations between the numbers of posterior functional contacts (FCs) and selected nutrient intakes and serum/plasma nutrient values in 3,554 adults 25 years of age and older from the 2003–2004 National Health and Nutrition Examination Survey (NHANES). Materials and Methods: FCs consist of the number of zones of contact between the maxillary and opposing mandibular posterior teeth when the maxillary and mandibular posterior teeth are together. There were 16 possible zones of contact. Nutrient intakes were calculated from one 24-h dietary recall and selected nutritional biochemistries were measured. Multivariate linear regression was used to examine the association between the numbers of FCs and nutrient intakes or serum/plasma nutrient values, controlling for potential confounding variables. Results: Males with 6 or more FCs had higher vitamin A (p < 0.05), C (p < 0.05), E (p < 0.01) and B-6 intakes (p < 0.05) than those with 5 or fewer FCs. Females with 6 or more FCs had higher dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate intakes (p < 0.05) than those with 5 or fewer FCs. Males and females with 6 or more FCs had higher serum `-carotene than those with 5 or fewer FCs (p < 0.05 and p < 0.001, respectively). Males with 6 or more FCs had higher serum folate levels than those with 5 or fewer FCs (p < 0.01), and females with 6 or more FCs had higher serum vitamin C levels than those with 5 or fewer FCs (p < 0.05). Conclusions: Dietary intakes and serum levels of certain nutrients differ by the number of FCs present. Key words: dietary recall, functional contacts, NHANES, serum nutrients Oral Health Prev Dent 2014;12:265-276 doi: 10.3290/j.ohpd.a31666
D
entate status is an important factor affecting dietary intake and nutritional status. Adults who are edentulous or have fewer natural teeth are less likely to eat certain fruits and vegetables and have lower intakes of energy, protein, carotenes, vitamins A and C, folate and B vitamins, calcium, iron, zinc and dietary fiber (Joshipura et al, 1996; Sheiham and Steele, 2001; Marshall et al, 2002; Nowjacka
Nutritional Epidemiologist, Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Health and Nutrition Examination Statistics, Hyattsville, MD, USA.
b
Dental Epidemiology Officer, Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Health Examination Statistics, Hyattsville, MD, USA.
Correspondence: Bruce A. Dye, National Center for Health Statistics, Division of Health Examination Statistics, 3311 Toledo Rd, Room 4416, Hyattsville, MD 20782, USA. Tel: +1-301-458- 4199, Fax:+1-301-458-4029. Email: [email protected]
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Submitted for publication: 07.06.12; accepted for publication: 02.03.13
Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007; Ervin and Dye, 2009). They eat a less varied diet and have a lower overall diet quality (Marshall et al, 2002; Sahyoun et al, 2003). In addition, serum levels for some nutrients are lower among those with a compromised dentition (Sheiham and Steele, 2001; Nowjack-Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007). Another approach used to examine the association between dietary intake and dentition is to look at functional tooth units. A functional unit (FU), also known as a functional contact, is defined as any pair of opposing natural or prosthetic teeth (Hildebrand et al, 1995). Hildebrand et al (1997) assert that research that focuses only on the number of teeth present in a person’s mouth may give an overestimation of a person’s chewing potential be-
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cause it does not take into account the functional arrangement of the teeth. In contrast, FU measures take into account the basic functional interaction between upper and lower teeth and the number and type of teeth. Consequently, FUs are more discriminatory and descriptive of chewing and swallowing difficulties and food avoidances than merely counting the number of teeth present or identifying the percentage of subjects who are edentulous. The use of FUs and the analogous occluding pairs in dental research has been limited and not consistent. For example, Morita et al (2007) categorised posterior occlusal pairs (POP) for analysis as zero POPs, 1 to 3 POPs and 4 to 12 POPs; in contrast, de Andrade et al (2009) and Sheiham and Steele (2001) used zero POPs, 1 to 4 POPs and 5 to 8 POPs in research that scored one contact per occluding dental pair for a total of four possible pairs for each side of the mouth. These researchers only looked at natural teeth, whereas Sahyoun et al (2003) included a category for full dentures. None of these studies included third molar pairings. A limited amount of research has been conducted on the relationships between FUs and food and nutrient intakes. This research has used the threecategory POPs in the zero to 8 range. In general, those with no pairs of posterior teeth or fewer pairs of teeth had lower intakes of kilocalories, protein, dietary fiber, calcium, iron, phosphorus, B-vitamins, carotenes and vitamins A, C and E than those with 5 to 8 pairs of teeth (Sheiham and Steele, 2001; Sahyoun et al, 2003; de Andrade et al, 2009). Older adults who wore dentures or had less than five POPS had lower overall diet quality and may consume a less varied diet (Sheiham and Steele, 2001; Sahyoun et al, 2003). Some of these researchers have also looked at the relationships between FUs and serum nutrients and reported that blood levels of vitamin C and beta carotene were significantly and positively associated with number of pairs of posterior teeth (Sheiham and Steele, 2001; Sahyoun et al, 2003). As described earlier, none of these studies looked at FUs that included third molar pairings. In addition, none of them looked at males and females separately. It has been shown that males and females differ in their food choices, energy and nutrient intakes as well as overall diet quality (Federation of American Societies for Experimental Biology, 1995; Bates et al, 1999; Baker and Wardle, 2003; U.S. Department of Agriculture, 2007). In our previous research, we found differences in food and nutrient intakes by
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number and type of teeth present, and these differences varied by sex (Ervin and Dye, 2009; Ervin and Dye, 2011). The purpose of this study was to examine the associations between the number of posterior functional contacts, including third molar pairings, and selected nutrient intakes and serum nutrient values among adults in the National Health and Nutrition Examination Survey (NHANES) 2003–2004. The hypothesis tested was that nutrient intakes and serum nutrient values are positively associated with the number of functional contacts and the significant associations are different for males vs females.
MATERIALS AND METHODS NHANES is a cross-sectional nationally representative health and nutrition examination survey conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention. The survey design is a complex, stratified, multistage probability sample of the civilian, noninstitutionalised US population. NHANES 2003– 2004 included oversamples of low-income persons, adolescents 12–19 years old, persons 60 years of age and older, African Americans and Mexican Americans. The survey includes an interview administered in the home and a subsequent health examination performed at a mobile examination center (MEC). Trained interviewers conducted the interviews. Trained dentists performed the oral health examinations at the MEC and the overall quality of the dentate status data was considered to be excellent (Dye et al, 2007; Dye et al, 2008). Additional details about this survey can be found at: http://www. cdc.gov/nchs/about/major/nhanes/datalink.htm.
Sample population The examination of functional occlusal contacts was performed only on adults ≥ 25 years of age. A total of 6,308 adults, 25 years of age and over, were eligible to participate in NHANES 2003–2004. Of the eligible sample, 4,568 adults (72%) 25 years of age and over participated in the household interview. Approximately 94% (4,284) of the household interview sample also participated in the MEC exam. Only those adults who participated in both the household interview and the MEC exam were included in the analytic sample (4,284).
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Participants were excluded from this sample if their dietary recall was not complete and reliable (261), any of the laboratory measures were missing (273), the functional contacts information was incomplete or missing (190), their response to the dietary supplement use question was missing (6) or their responses to the levels of education or smoking questions were missing (7). The final analytic sample consisted of 3,547 adults ≥ 25 years of age.
Predictor and confounding variables The analysis was based on the number of posterior functional contacts (FCs) which consists of the number of posterior occluding pairs (POPs) of teeth (premolars and molars, including third molars). The NHANES functional contact assessment required the examiner to evaluate the relationship between the maxillary posterior teeth to the opposing mandibular posterior teeth after the participant had closed their maxillary and mandibular posterior teeth together into a normal, static position. There were 8 possible zones of contact in the posterior region for each of the left and right areas of the mouth. The premolars were counted as a single zone and the molars were counted as two zones each. Contacts between two natural teeth, two denture teeth or a combination of natural and denture teeth were counted as a functional contact for this study, while the absence of POPs was counted as no FC. The maximum number of posterior contacts was 16. The FCs were treated as discrete variables in the regression analyses. We grouped functional contacts into four categories for the first set of analyses. These categories consisted of no FC, 1 to 5 FCs, 6 to 11 FCs and 12 to 16 FCs, including information from the third molars. The upper break point was based on results from the preliminary screening which revealed a break in nutrient intakes between 11 and 12 contacts. The lower break point was set at five to be consistent with other work currently being conducted on functional contacts (Dye and Steele, personal communication). In the second set of analyses, the four catgeories of contacts were collapsed to two more comprehensive categories: 5 or fewer FCs vs 6 or more FCs. Our previous analyses have revealed that age, race/ethnicity, education and smoking status were usually significantly associated with the nutrient intakes (Ervin and Dye, 2009; Ervin and Dye, 2011).
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Other researchers have controlled for some if not all of these variables (Joshipura et al, 1996; Sheiham and Steele, 2001; Nowjack-Raymer and Sheiham, 2003; Sahyoun et al, 2003; Nowjack-Raymer and Sheiham, 2007). These variables were treated as potential confounding variables and were defined as follows in the present analyses. Since only adults 25 years and older received the functional contacts examination, age was categorised into 3 groups: 25–39 years old, 40–59 years old and 60 years of age or over. Race/ethnicity consisted of non-Hispanic Whites, non-Hispanic Blacks, Mexican Americans and all other race and ethnic groups. Education was also categorised into three groups: less than high school (HS), high school diploma including a General Education Development high school equivalency degree (GED), or more than high school. The smoking status variable was based on cigarette smoking only. Participants who never smoked or smoked less than 100 cigarettes in their lifetime were labeled ‘never smokers’; participants who smoked at least 100 cigarettes in their lifetime, but were not currently smoking were labeled ‘former smokers’; and participants who had smoked at least 100 cigarettes in their lifetime and currently smoked some days or everyday were labeled ‘current smokers.’ Dietary supplement use was included as a confounding variable when the response variables were serum/plasma nutrient values. During the NHANES 2003–2004, questions about dietary supplement use were asked only during the household interview which may have taken place several weeks before the MEC exam where blood samples were collected. Because of this time lag, it is possible that serum/plasma nutrient values may not reflect recent supplement use especially if the participant changed their pattern of supplement intake prior to the MEC exam.
Response variables Trained interviewers conducted dietary recall interviews using an automated data collection system during the MEC examination. Detailed descriptions of the 2003–2004 dietary interview and data processing procedures can be found under the dietary interview components at http://www.cdc.gov/ nchs/nhanes/nhanes2003–2004/exam03_04. htm. Although two dietary recalls were collected about 3 to 10 days apart, only the first day’s (day 1) recall was used in these analyses. The intent was to examine usual intakes of the FC categories
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rather than estimating usual intakes of individuals, and more participants completed the day-1 recall than both recalls. Nutrient intakes were calculated from the 24-h dietary recalls. Since only the impact of the number of occlusal contacts on nutrient intakes from food was of interest, nutrient intakes from dietary supplements were not calculated in these analyses. Kilocalories, protein, dietary fiber, alpha- and `-carotene, vitamins A, C, E and B-6 and total folate were analysed. Trained phlebotomists performed the blood collections during the MEC examination. Detailed descriptions of the laboratory procedures can be found under the 2003–2004 laboratory files at h t t p : // w w w . c d c . g o v / n c h s / n h a n e s / nhanes2003–2004/lab03_04.htm. The following nutritional biochemistries were examined: serum retinol (ug/dL), serum `-carotene (ug/dL), serum vitamin C (mg/dL), serum _-tocopherol (mg/dL), plasma vitamin B-6 (nmol/L) and serum folate (ng/mL).
Statistical tests Data were analysed using SAS for Windows (release 9.2; SAS Institute; Cary, NC, USA) and SUDAAN (release 10.0; Research Triangle Institute; Research Triangle Park, NC, USA). Day-1 dietary sample weights were used. Since day-1 dietary recall data were used in the analyses, sample weights specially created for the day-1 recalls were used (see the analytic notes for the day 1 dietary interview – total nutrient intakes; http://www.cdc.gov/ nchs/data/nhanes/nhanes_03_04/dr1tot_c.pdf). Sample weights were employed that incorporated the differential probabilities of selection and included adjustments for oversampling of certain populations and non-response to the household interview and MEC examination. The percentage distributions and standard errors were calculated for the confounding and predictor variables by sex. Multivariate linear regression models were run to examine the association between the FC variables and dietary nutrient intakes and serum/plasma nutrient values, with control for the potential confounding variables. In addition, we controlled for caloric intake in all of the models examining nutrient intakes, since nutrient intake is often positively correlated with caloric intake (Willett and Stampfer, 1998), and dietary supplement use in all of the models examining serum/plasma nutrient values. Least squares means (LSM) were also compared
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to determine whether significant differences existed in intakes or blood levels among the FC categories. When the four FC categories were examined, the no-FC, 1- to 5-FCs and 6- to 11-FCs categories were compared to the 12- to 16-FCs category (reference). When the two more comprehensive FC groups were examined, we compared the intakes or blood levels of the 5 or fewer FCs group to those of the 6 or more FCs group. Separate multivariate linear regression models were constructed for each sex. Nutrient values were transformed using a log10 transformation prior to regression analyses for those nutrients that deviated substantially from normality. Since zero cannot be log-transformed, when a nutrient intake was zero, a small value greater than zero but less than the lowest intake reported for that nutrient was added to all of the intakes. The antilogs of the least squares means and standard errors from the regression analyses are reported in the tables. A Satterthwaite-adjusted F-statistic was employed to test whether the FC variable was significantly associated with nutrient intakes or serum/ plasma nutrient values. When there was a significant association, a Satterthwaite-adjusted F-statistic was used to determine which FC categories were significantly different from the reference category (12 or more FCs). The critical value was set at p < 0.05. For nutrients that were transformed, the significance tests were based on the log-transformed values.
RESULTS Table 1 presents the weighted distribution for selected characteristics of the analytic sample. The sample was nearly equally distributed between males (49%) and females (51%) and included primarily non-Hispanic white persons (75% for males and 76% for females). More males than females were in the 25–39- and 40–59-year-old age groups, but the opposite pattern was true for participants who were ≥ 60 years of age. A little more than onefourth of the sample had a high school or highschool equivalency degree (26%), while 56% had more than a high-school education. A larger proportion of males than females were current or former smokers (61% males vs 46% females). About half of the males (51%) reported taking supplements in the past 30 days, but nearly two-thirds of the females (63%) reported taking supplements during that interval. Most adults (83%) had six or more FCs.
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Nutrient intakes Table 2 presents results for the association between the four-category classification of functional contacts and nutrient intakes. Among males, FCs were significantly associated with caloric intake (p < 0.05) and vitamin E (p < 0.05). The groups with zero contacts (p < 0.01) and 6 to 11 FCs (p < 0.05) had significantly lower caloric intakes than the reference group (12 to 16 FCs). The zero-FC (p < 0.001), 1- to 5-FCs (p < 0.005) and 6- to 11-FCs (p < 0.05) categories all had significantly lower vitamin E intakes than the reference group. Among females, FCs were significantly associated with dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate (p < 0.05) intakes. All three groups had lower dietary fiber and vitamin E intakes than that of the reference group. The p-values were less than 0.05 for each comparison to the reference category for dietary fiber. The p-values for each comparison for vitamin E were p < 0.005 for 0 contacts, p < 0.05 for 1 to 5 contacts and p < 0.05 for 6 to 11 contacts. The groups with zero contacts and 1 to 5 contacts had lower folate intakes than the reference group (p < 0.05 for each comparison). None of the other nutrients were significantly associated with functional contacts for males or females. A few more nutrients were significantly associated with FCs in males when the contacts were categorised as being above or below a threshold of 5 contacts (Table 3). Males with more than 5 contacts had significantly higher vitamin A (p < 0.05), C (p < 0.05), E (p < 0.01) and B-6 intakes (p < 0.05) than those with 5 or fewer contacts. For females, the same three nutrients that were significant when 4 FC categories were used were also significant when 2 categories were used. Females with more than 5 contacts had significantly higher dietary fiber (p < 0.05), vitamin E (p < 0.05) and folate intakes (p < 0.05) than those with 5 or fewer contacts. None of the other nutrients were significantly associated with FCs for males or females.
Table 1 Weighted distribution of characteristics among survey participants by sex, NHANES 2003–2004
Characteristics
Males (n = 1,749)
Females (n = 1,798)
% (SE)
% (SE)
Age 25–39 years
32.2 (1.5)
29.9 (1.9)
40–59 years
42.8 (1.4)
40.8 (2.0)
60 years and older
24.9 (0.9)
29.3 (1.3)
Non-Hispanic white
75.4 (3.3)
75.7 (3.4)
Non-Hispanic black
9.3 (1.6)
10.5 (1.9)
Mexican American
7.6 (2.2)
6.0 (1.7)
Other
7.7 (1.1)
7.8 (1.0)
Less than high school
17.2 (1.4)
17.9 (1.9)
High school or GED*
26.2 (1.7)
26.0 (1.3)
Greater than high school
56.6 (2.2)
56.1 (2.4)
Never
38.5 (1.6)
54.4 (1.4)
Former
32.8 (1.4)
24.4 (1.5)
Current
28.6 (1.4)
21.2 (1.5)
Yes
50.6 (1.6)
63.0 (1.8)
No
49.4 (1.6)
37.0 (1.8)
No FCs
5.4 (1.0)
4.0 (0.5)
1–5 FCs
11.4 (1.3)
12.6 (1.7)
6–11 FCs
38.2 (1.7)
38.1 (1.0)
12–16 FCs
45.0 (1.7)
45.3 (2.2)
Race and ethnicity
Education
Smoking status
Use of dietary supplements
Functional Contacts †
* GED is a General Education Development high-school equivalency degree. † Functional contacts were defined as the number of posterior occluding pairs (POPs) of teeth (premolars and molars, including third molars).
Serum/plasma nutrients Serum/plasma nutrients were also examined based on the four- and two-category FC groups. Serum`-carotene levels were significantly associated with functional contacts for both males and females regardless of whether four categories
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(Table 4) (males: p < 0.05; females: p < 0.01) or two categories were used (Table 5) (p-values reported below with each comparison). Males with zero contacts or 1 to 5 contacts had lower serum `-carotene levels than the reference group (p < 0.001 and p < 0.05, respectively) and males
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Table 2 Associations between FCs in four categories and nutrient intakes for adults ≥ 25 years of age adjusted for confounding variables: United States, 2003–2004* Males Nutrient
p-value for relationship†
Kilocalories (kcal)
< 0.050
LSM (SE)‡
Females p-value for pairwise comparisons¶
p-value for relationship†
LSM (SE)‡
p-value for pairwise comparisons¶
0.505
0 contacts
2224 (135)
< 0.010
1862 (76)
0.885
1–5 contacts
2507 (71)
0.061
1812 (77)
0.573
2530 (51)
< 0.050
1794 (43)
0.264
2687 (52)
•
1875 (40)
•
6–11 contacts §
12–16 contacts Protein (g)
0.486
0.393
0 contacts
95 (2)
0.163
65 (5)
0.589
1–5 contacts
97 (3)
0.530
66 (2)
0.353
6–11 contacts
97 (1)
0.295
69 (1)
0.406
12–16 contacts§
99 (2)
•
68 (1)
•
Dietary fiber (g)
0.190
< 0.050
0 contacts
17.2 (0.9)
0.258
12.2 (0.6)
< 0.050
1–5 contacts
17.6 (0.9)
0.462
13.0 (0.3)
< 0.050
16.9 (0.5)
0.084
13.3 (0.2)
< 0.050
18.4 (0.6)
•
14.6 (0.5)
•
0.182
6–11 contacts §
12–16 contacts
††
Vitamin A, RAE (μg)
0.194
0.280
0 contacts
338 (1.2) ‡‡
0.050
327 (1.2)‡‡
1–5 contacts
422 (1.1)
0.132
362 (1.1)
< 0.050
6–11 contacts
440 (1.1)
0.392
386 (1.0)
0.368
12–16 contacts§
479 (1.0)
•
413 (1.0)
•
††
_-carotene (μg)
0.555
0.396
0 contacts
21.2 (1.7) ‡‡
0.346
17.5 (1.3)‡‡
1–5 contacts
25.3 (1.4)
0.234
33.9 (1.2)
0.875
34.0 (1.2)
0.656
34.0 (1.2)
0.847
36.9 (1.1)
•
35.4 (1.2)
•
6–11 contacts §
12–16 contacts
††
`-carotene (μg)
0.154
< 0.050
0.341
0 contacts
490 (1.3) ‡‡
0.073
522 (1.2)‡‡
0.097
1–5 contacts
649 (1.1)
< 0.050
640 (1.1)
0.114
6–11 contacts
701 (1.1)
0.172
713 (1.1)
0.717
12–16 contacts§
851 (1.1)
•
741 (1.1)
††
Vitamin C (mg)
270
0.098
0.897
0 contacts
35.5 (1.2) ‡‡
0.108
43.5 (1.1)‡‡
0.810
1–5 contacts
36.9 (1.1)
< 0.050
44.0 (1.1)
0.865
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6–11 contacts §
12–16 contacts
Vitamin E as _-tocopherol equivalents (mg)††
51.3 (1.1)
0.672
43.1 (1.1)
0.649
53.8 (1.1)
•
45.0 (1.1)
•
< 0.050
< 0.050
0 contacts
5.2 (1.1)‡‡
< 0.001
4.2 (1.1)‡‡
< 0.005
1–5 contacts
5.8 (1.0)
< 0.005
4.8 (1.0)
< 0.050
6.0 (1.1)
< 0.050
4.9 (1.0)
< 0.050
6.9 (1.0)
•
5.4 (1.0)
•
6–11 contacts §
12–16 contacts
Vitamin B-6 (mg)††
0.275
0.488
0 contacts
1.7 (1.1)‡‡
0.098
1–5 contacts
1.7 (1.0)
0.075
1.3 (1.1)‡‡
0.414
6–11 contacts
1.8 (1.1)
0.350
1.3 (1.0)
0.786
12–16 contacts§
2.0 (1.0)
•
1.4 (1.0)
•
††
0.216
Folate (μg)
0 contacts
1–5 contacts 6–11 contacts §
12–16 contacts
< 0.050
0.052
260 (1.0)‡‡
< 0.050
376 (1.0)
0.081
277 (1.0)
< 0.050
378 (1.1)
0.252
299 (1.0)
0.112
411 (1.0)
•
310 (1.0)
•
344 (1.1)
‡‡
¶¶
* Confounding variables in model: age group, race/ethnicity, education and smoking status. When the outcome variable was nutrient intake kilocalories were included in the model. † F-test to establish whether there is a relationship between the FC variable and nutrient intakes, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ‡ LSM = Least Squares Means; SE = Standard error. ¶ F-test for pairwise comparisons of 0 contacts, 1–5 contacts, and 6–11 contacts to the reference category, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. § Reference category. †† Nutrient values were transformed using a log10 transformation prior to regression analyses; all statistical tests were conducted using the log transformed values. ‡‡ All values shown are the antilog of the log10 values for least squares means and standard errors from the linear regression. All estimates shown were statistically reliable as the log-transformed values unless otherwise noted. ¶¶ Estimate does not meet the standard of reliability and precision.
with ≤ 5 FCs had lower serum levels than those with > 5 FCs (p < 0.05). Females with zero contacts or 1 to 5 contacts had lower serum `-carotene levels than the reference group (p < 0.005 and p < 0.001, respectively) and those with ≤ 5 FCs had lower serum levels than those > 5 FCs (p < 0.001). Serum _-tocopherol was significantly associated with FCs when classified into four categories for males (p < 0.05). Those with zero contacts had lower serum levels than those with 12 or more contacts (p < 0.001). Males with ≤ 5 or fewer contacts had lower serum folate levels than those with > 5 contacts (p < 0.01) and females with ≤ 5 or fewer contacts had lower serum vitamin C levels than those with > 5 contacts (p < 0.05). None of the other serum or plasma nutrients were significantly associated with FCs for males or females.
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DISCUSSION In this study, we demonstrated that there were positive associations between the number of posterior functional contacts and some nutrient intakes, but the patterns varied by gender and by the scheme used for categorising the number of contacts. When four categories were considered, males with 12 or more contacts (reference group) consumed more vitamin E than any of the other FC levels and more calories than those with zero contacts or 6 to 11 contacts. Females with 12 or more contacts had higher dietary fiber and vitamin E intakes than any of the other FC categories and higher folate intakes than those with 5 or fewer contacts. When the categories were collapsed into two more comprehensive FC groups, males who had more than 5 contacts had higher vitamin A, B-6 and C intakes
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Table 3 Associations between 5 or less vs more than 5 FCs and nutrient intakes for adults ≥ 25 years of age adjusted for confounding variables: United States, 2003–2004* Males Nutrient
Females
†
LSM (SE)
p-value
≤ 5 contacts
2430 (76)
0.070
> 5 contacts
2612 (38)
‡
†
LSM (SE)
p-value‡
1828 (56)
0.898
Kilocalories (kcal)
1837 (23)
Protein (gm) ≤ 5 contacts
97 (2)
0.599
65 (2)
0.149
> 5 contacts
98 (1)
69 (1)
18 (0.8)
0.910
13 (0.3)
< 0.050
18 (0.4)
14 (0.4)
≤ 5 contacts
397 (1.1)§
< 0.050
355 (1.1)§
0.052
> 5 contacts
459 (1.0)
400 (1.0)
_-carotene (μg)¶
≤ 5 contacts
24.1 (1.3)§
0.211
29.3 (1.2)§
0.438
> 5 contacts
35.5 (1.1)
34.7 (1.1)
≤ 5 contacts
604 (1.1)§
0.057
612 (1.1)§
0.095
> 5 contacts
776 (1.0)
728 (1.1)
≤ 5 contacts
36.6 (1.1)§
< 0.050
44.0 (1.1)§
0.977
> 5 contacts
52.6 (1.1)
44.1 (1.1)
≤ 5 contacts
5.6 (1.0)§
< 0.010
4.7 (1.0)§
< 0.050
> 5 contacts
6.4 (1.0)
5.1 (1.0)
≤ 5 contacts
1.7 (1.0)§
< 0.050
1.3 (1.1)§
0.177
> 5 contacts
1.9 (1.0)
1.3 (1.0)
Dietary fiber (g) ≤ 5 contacts > 5 contacts Vitamin A, RAE (μg)
¶
`-carotene (μg)¶
Vitamin C (mg)¶
Vitamin E as _-tocopherol equivalents (mg)¶
Vitamin B-6 (mg)¶
Folate (μg)¶ ≤ 5 contacts
368 (1.0)§
0.078
274 (1.0)§
< 0.050
> 5 contacts
395 (1.0)
304 (1.0)
* Confounding variables in model: age group, race/ethnicity, education, and smoking status. When the outcome variable was nutrient intake kilocalories were included in the model. † LSM = Least Squares Means; SE = Standard error. ‡ F-test to establish whether there is a relationship between the FCs variable and nutrient intakes, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ¶ Nutrient values were transformed using a log10 transformation prior to regression analyses; all statistical tests were conducted using the log transformed values. § All values shown are the antilog of the log10 values for least squares means and standard errors from the linear regression. All estimates shown were statistically reliable as the log-transformed values.
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Table 4 Associations between number of FCs in four categories and serum/plasma nutrient levels for selected nutrients for adults ≥ 25 years of age adjusting for confounding variables in the models: United States, 2003–2004* Males Nutrient†
p-value for relationship‡
Retinol (ug/dL)
0.456
Females
¶
LSM (SE)
p-value for pairwise comparisons§
p-value for relationship‡
LSM (SE)
p-value for pairwise comparisons§
¶
0.348
0 contacts
65.0 (2.0)
0.852
61.1 (2.4)
0.079
1–5 contacts
63.1 (2.0)
0.227
55.8 (1.1)
0.207
64.2 (0.6)
0.163
57.4 (1.1)
0.856
65.4 (0.6)
•
57.2 (0.8)
•
6–11 contacts ††
12–16 contacts
`-carotene (ug/dl)
< 0.050
< 0.010
0 contacts
9.0 (1.1)
< 0.001
14.9 (1.3)
< 0.005
1–5 contacts
13.1 (1.6)
< 0.050
16.2 (1.3)
< 0.001
14.9 (0.9)
0.054
20.7 (1.5)
0.106
17.6 (1.0)
•
23.6 (1.3)
•
6–11 contacts ††
12–16 contacts
Vitamin C (mg/dl)
0.110
0.064
0 contacts
0.70 (0.06)
< 0.010
0.85 (0.06)
< 0.010
1–5 contacts
0.85 (0.06)
0.541
0.99 (0.03)
0.179
6–11 contacts
0.91 (0.03)
0.711
1.03 (0.02)
0.252
12–16 contacts††
0.89 (0.03)
•
1.08 (0.04)
•
_-tocopherol (mg/dl)
< 0.050
0.362
0 contacts
1.18 (0.06)
< 0.001
1.31 (0.06)
< 0.010
1–5 contacts
1.42 (0.05)
0.927
1.51 (0.06)
0.836
1.41 (0.01)
0.712
1.48 (0.04)
0.860
1.43 (0.03)
•
1.49 (0.03)
•
6–11 contacts ††
12–16 contacts
Vitamin B-6 (nmol/l)
0.331
0.337
0 contacts
48.0 (5.2)
1–5 contacts
59.7 (3.5)
6–11 contacts
69.0 (8.1)
12–16 contacts††
64.2 (4.7)
Folate (ng/mL)
0.108
0.403 ‡‡
0 contacts
10.7 (1.0)
< 0.050
1–5 contacts
12.1 (0.8)
0.050
14.5 (0.6)
0.250
13.4 (0.3)
0.338
14.7 (0.4)
0.079
14.4 (0.8)
•
15.4 (0.3)
•
6–11 contacts ††
12–16 contacts
* Confounding variables in model: age group, race/ethnicity, education, smoking status and dietary supplement use. † Serum was used for retinol, `-carotene, vitamin C, _-tocopherol and folate; plasma was used for vitamin B-6. ‡ F-test to establish whether there is a relationship between the FCs variable and serum/plasma nutrients, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. ¶ LSM = Least Squares Means; SE = Standard error. § F-test for pairwise comparisons of 0 contacts, 1–5 contacts, and 6–11 contacts to the reference category, based on the Satterthwaite-adjusted F-statistic. The critical value was p < 0.05. †† Reference category. ‡‡ Estimate does not meet the standard of reliability and precision.
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Table 5 Associations between 5 or less vs more than 5 FCs and serum/plasma nutrient levels for selected nutrients for adults ≥ 25 years of age adjusting for confounding variables in the models: United States, 2003–2004* Males Nutrient†
Females
‡
LSM (SE)
p-value
≤ 5 contacts
63.7 (1.7)
0.487
> 5 contacts
64.9 (0.5)
`-carotene (ug/dl)
≤ 5 contacts
12.0 (1.2)
> 5 contacts
16.3 (0.7)
Vitamin C (mg/dl)
≤ 5 contacts
0.81 (0.04)
> 5 contacts
0.90 (0.02)
¶
‡
LSM (SE)
p-value¶
57.0 (1.3)
0.807
Retinol (ug/dl)
57.3 (0.6)
< 0.050
16.1 (1.0)
< 0.001
22.2 (1.2)
0.061
0.96 (0.03)
< 0.050
1.06 (0.03)
_-tocopherol (mg/dl) ≤ 5 contacts
1.35 (0.04)
> 5 contacts
1.42 (0.02)
0.094
1.46 (0.05)
0.645
1.49 (0.02)
Vitamin B-6 (nmol/l) ≤ 5 contacts
71.3 (10.0)
> 5 contacts
81.2 (3.4)
0.281
56.8 (3.2)
0.055
66.4 (4.9)
Folate (ng/ml) ≤ 5 contacts
11.7 (0.6)
> 5 contacts
13.9 (0.4)
< 0.010
17.9 (3.7)
0.454
15.1 (0.3)
* Confounding variables in model: age group, race/ethnicity, education, smoking status and dietary supplement use. † Serum was used for retinol, `-carotene, vitamin C, _-tocopherol and folate; plasma was used for vitamin B-6. ‡ LSM = Least Squares Means; SE = Standard error. ¶ p-value for association of FCs with serum/plasma nutrients, based on the Satterthwaite-adjusted F-statistic. The critical value was p< 0.05.
than those with 5 or fewer contacts. Females who had more than 5 contacts had higher dietary fiber, vitamin E and folate intakes than those with 5 or fewer contacts. Certain serum nutrients were also associated with the number of posterior FCs. Males with 12 or more contacts had higher serum _-tocopherol levels than those with zero posterior contacts. Five or fewer FCs appeared to represent a critical boundary for several nutrients. When the 4-category model was examined, those with 12 or more contacts had higher serum `-carotene levels than those with 5 or fewer teeth. When two FC categories were used, those with more than 5 contacts had higher serum `-carotene levels than those with 5 or fewer contacts. These patterns were true for males and females. In addition, males with more than 5 contacts had higher serum folate and females with
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more than 5 contacts had higher serum vitamin C than those with 5 or fewer contacts. One reason those with more FCs may have had higher intakes of these nutrients could be because they consumed more energy and foods. Increasing caloric intake could increase intakes of nutrients, but we controlled for calories in the nutrient analyses. Another possibility is that those with more FCs consumed more foods that were especially rich in dietary fiber, vitamins A, C, B-6, E or folate. Readyto-eat cereals are rich sources of dietary fiber, folate and vitamins A, C, E and B-6. Yeast breads and legumes are rich sources of folate and dietary fiber (Cotton et al, 2004; Maras et al, 2004; U.S. Department of Agriculture, 2009). Beginning in January 1998, Federal law required that all enriched cereal grains be fortified with folate. These foods include enriched bread, pasta, flour, breakfast ce-
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real and rice (Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, 1998). Dark green leafy vegetables and orange and grapefruit juices are excellent sources of folate and vitamin C, while dark green leafy vegetables and deep yellow or orange vegetables are excellent sources of vitamin A. Organ meats are rich sources of vitamins A and B-6 and nuts and seeds are rich sources of dietary fiber and vitamin E. Cooked cereals and dark green vegetables are also abundant sources of folate; vegetable margarine, oils and salad dressings are good sources of vitamin E; fruits and vegetables are excellent sources of dietary fiber and vitamin C; and dairy products are excellent sources of vitamin A (Cotton et al, 2004; Maras et al, 2004; U.S. Department of Agriculture, 2009). Finally, other factors not present in these models, such as diet and health knowledge, food preferences and income, might have contributed to some of these differences. For instance, those with more FCs might have had more diet and health knowledge and chosen foods richer in dietary fiber, vitamins A, C, B-6, E or folate. A few other studies have looked at nutrient intakes or serum/plasma nutrients in relationship to the number of pairs of occluding teeth in older adults. Depending on the study, older adults with zero posterior occlusal pairs (POPs) or fewer POPs had lower intakes of a broad range of nutrients including calories, protein, carbohydrate, dietary fiber, selected minerals, folacin, carotenes and vitamins A, C and E (Sheiham and Steele, 2001; Marshall et al, 2002; Sahyoun et al, 2003; de Andrade et al, 2009). They also had lower serum vitamin C and beta carotene levels (Sheiham and Steele, 2001; Sahyoun et al, 2003). None of these studies included younger and middle-age adults. These results are consistent with results from our earlier studies that examined only older adults (Ervin and Dye, 2009; Ervin and Dye, 2011). Results from the present study extend the evidence to include younger and middle-age adults. There may be a number of reasons why the results for serum nutrient values do not correspond with those from the 24-h recalls. Measurement of dietary intake is imprecise, one dietary recall does not reflect an individual’s usual intake and nutrient databases may be incomplete or imprecise (Dwyer, 1999). While plasma and serum levels of nutrients tend to reflect recent dietary intake, other factors may affect nutrient concentrations in biologic samples, including the intake of other nutrients, lifestyle factors, e.g. smoking or physical activity, use
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of oral contraceptive agents, genetic influences, fluctuations resulting from diurnal variation and meal consumption, medications, infection, inflammation and stress (Gibson, 1990; Hunter, 1998). Strong homeostatic controls may limit the interpretability of plasma or serum nutrient concentrations as a measure of dietary intake for some nutrients. For instance, in well-nourished populations, liver stores of vitamin A may be large enough to buffer serum levels over a wide range of dietary vitamin A intakes (Hunter, 1998). In other cases, homeostatic mechanisms maintain nearly normal plasma or serum nutrient concentrations in the presence of severe depletion of bodily stores (Gibson, 1990). Functional contacts may be a better indicator of the association between dentition status and dietary intake than total tooth count or other measures of impaired dentition status. In previous research, the present authors found that when total tooth count was treated as a continuous variable or collapsed into categories, only _- and `-carotene and vitamin C intakes were significantly associated with tooth count (Ervin and Dye, 2009; Ervin and Dye, 2011). In the current study, many more significant associations with nutrient intake were found when posterior FCs were used. Sahyoun et al (2003) also reported that the number of posterior pairs of teeth was more strongly associated with nutritional status in older adults than the total number of teeth or the number of posterior teeth. There are limitations to this study. These data were cross sectional in nature and causal associations thus cannot be established based on these results. Many comparisons were performed in this study, so there is a chance of having rejected a hypothesis that is actually true. Nonetheless, these results are generally consistent with that of other researchers.
CONCLUSION In conclusion, dietary intakes and serum levels of certain nutrients differ by the number of functional contacts present. Most of these nutrients can be found in a wide variety of foods, including ones that should not present chewing difficulties. Data from this study suggest that the dental and nutrition communities need to develop programmes to help adults with limited posterior functional contacts improve their intakes of dietary fiber, vitamins A, C, B-6 and E, `-carotene and folate. Although the
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study design used in this research is not sufficient to recommend changes based on the study findings, this study does suggests that from a US population perspective, functional contact replacement and rehabilitation to a status of 6 or more posterior functional contacts could potentially improve dietary intakes of key nutrients. Nevertheless, clinical dentists should not rely on these findings alone but also should consider other, individual factors in recommending posterior dental prostheses to replace lost functional contacts.
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