434
Alveolar Bone Loss in Patients with Long-Term Supportive Care *
Cynthia A. Layport, George
W.
Greco,f and
Walter T. McFall, Jr. *
Radiographic record audits were conducted on 63 patients diagnosed as having Periodontitis who had been treated and maintained for 10 years or longer in dental school clinics. Acceptable bite-wing radiographs were available for 50 of these patients. Bitewing radiographs taken 8 to 34 years apart (mean 14.9 years) were assessed for bone loss. Recall maintenance had been accomplished for 60% of these patients at 6 to 9 month intervals, while 24% had been seen more frequently. The mean annual rate of bone loss was 0.037 mm (range of -0.19 to 0.20). There were no significant differences in bone loss between maxillary/mandibular, molar/premolar, or mesial/distal sites respectively. Alveolar bone loss in this dental school population compares well with other reported studies. Progression of disease as assessed by radiographie bone loss in treated and maintained Periodontitis patients is minimal. J Periodontol 1990;61:434-437.
Key
Words:
diography.
Periodontitis/prevention
and
control; periodontitis/diagnosis; bone loss/ra-
Radiographic assessment of alveolar bone loss in patients with Periodontitis can be used as a measure of the progression of disease on a longitudinal basis. It may actually be more reliable than clinical probing measurements over a long period of time.1 Boyle et al.2 reported a reduction of alveolar crest height measured radiographically of only 0.017 mm per year and determined that aging is not a factor in alveolar bone loss, provided periodontal health is maintained. Other reports have indicated that the rate of alveolar loss in patients with periodontal disease ranges between 0.03 mm and 0.07 mm per year.3-:i Maintenance therapy accomplished on a 2 to 4 month basis appears to halt the radiographie evidence of progression in most patients.6-9 Bone loss does occur in patients receiving periodontal treatment without adequate periodontal supportive care.10'" Few studies have utilized bite-wing radiographs, although clinically they are the most commonly used method to estimate bone loss. Selikowitz et al.3 used a 3M reader to measure bone loss on bite-wing radiographs in two private practices. Rohner et al.4 examined a dental school population using the technique described by Schei. The purpose of the present study was to assess the rate of radiographie alveolar bone loss in a group of patients treated and maintained in the predoctoral and graduate clinics of a dental school for a period of 10 or more years. Private Practice of Periodontics, Portland, or.
'Department of Periodontics, Carolina, Chapel Hill, NC.
School of
Dentistry, University
of North
MATERIALS AND METHODS The study population comprised 63 patients who had received treatment for periodontal disease and were then maintained in a dental school clinic for 10 years or longer. Criteria for record audit and clinical findings of these patients have been reported by Wood et al.12 During active treatment all patients received supragingival and subgingival scaling and root planing accompanied by oral hygiene instruction, performed by a predoctoral dental student or periodontal resident. Most patients received surgical therapy which included gingivectomy, flap surgery, flap curettage, osseous contouring, and osseous grafting. Bite-wing radiographs taken at least 8 years apart were available for 50 of these 63 patients. The long cone paralleling technique was used. Radiographs were considered to be acceptable if the cemento-enamel junction (CEJ), margin of a restoration, and interdental crest of bone were clearly visible. Radiographs with overlapping crown images or distorted vertical angulation were not used. If a restoration had been placed between the initial bite-wing radiograph and the final bite-wing radiograph, then these films were not used. Each radiograph was placed in a slide mount and projected onto a screen to achieve 10-fold magnification. An unexposed film with fine lines 1 mm apart was used to standardize the magnification at each reading session. Radiographs were separated so that the initial and final sets from each patient were not read at the same session. The cemento-enamel junction point was chosen as the coronal reference point since it is more reliable than the most occlusal point.3 When the CEJ was not visible due to
Volume 61 Number 7
the presence of a restoration, the most apical point of the restoration was used. The most coronal level of the alveolar bone, where the periodontal space was 0.2 mm when visible, was used as the apical reference point. Measurements were made on the projected images to .01 mm using a Boley gauge 4 The mesial and distal surfaces of the first and second molars and premolars were evaluated, generally with the molars being examined from the molar bite-wing and the premolars from the premolar bite-wing. Missing teeth and the presence of overhanging restorations were also noted. To determine the mean error of measurement, the distance from the coronal reference point to the apical reference point was scored at each site on ten randomly selected bitewings on three different occasions by the principal investigator (C.A.L.). A 2-week interval occurred between each scoring session to reduce bias. The difference between the two most discrepant measurements for each site determined the amount of error for that site. Mean error of measurement was obtained by totaling discrepancy values and dividing by number of sites scored. The mean error of measurement was found to be 0.4 mm. To obtain a measure of bone loss, the readable score for each post-maintenance site was subtracted from the initial bite-wing score for each site. The resultant bone level change was then divided by the number of years between radiographic examinations to achieve an annual bone loss score. The mean scores for each patient were used for statistical analysis using the Statistical Analysis System package.§ RESULTS
Radiographs from 13 of the 63 patients in the study population could not be used. There were no statistical differences in age, sex, recall interval, or maintenance classification between these 13 patients and the 50 patient sample used. At the time of the initial examination, the mean age of the 50 patients was 46.7 years, with a range of 24 to 67 years of age. There were 31 females and 19 males, and Caucasians comprised 84% of the sample. The mean interval between radiographs was 14.9 years, with a range of 8.4 to 34.3 years. Of a possible 1600 surfaces, 290 (145 posterior teeth) were missing at the initial radiographie examination and 150 sites (75 posterior teeth) were lost during the study; 176 sites were not included because the CEJ reference was obliterated by a restoration placed between the two sets of radiographs; 233 sites (20% of those present) could not be evaluated due to obstruction of the CEJ or alveolar crest. Most frequently the mesials of the mandibular first premolars were the sites that could not be accurately evaluated. Bone loss scores were obtained for 751 sites in the 50 patients. The average number of readable sites was 15 with a range of 4 to 30. The mean annual rate of bone loss for all patients was 0.037 mm (range -0.19 to 0.20). Maxil*MiItex Instruments, Lake Success, NY. §SAS Institute, Inc., Cary, NC.
LAYPORT, GRECO, Comparison of Annual Bone Maxillary and Mandibular Sites Table 1.
Patient
Site
49 50
375 376
McFALL
Loss Scores Between
Mean Bone Score*
Maxillary
Mandibular Difference *in mm,
±
435
0.045 ± 0.087 0.029 ± 0.065 0.017 ± 0.085
Value 0.0006 0.0023 0.1698
standard deviation.
Table 2. Comparison of Annual Bone Loss Scores Between Molar and Premolar Sites
Molar Premolar Difference *in mm,
±
Patient
Site
47
320 431
50
Mean Bone Score* 0.046 ± 0.075 0.036 ± 0.060 0.008 ± 0.055
Value 0.0001 0.0001 0.2886
standard deviation.
Table 3. Comparison of Annual Bone Loss Scores Between Mesial and Distal Sites
Mesial Distal Difference *in mm,
lary
±
Patient
Site
50 50
369 382
Mean Bone Score* 0.036 ± 0.067 0.039 ± 0.064 -0.003 ± 0.054
Value 0.0004 0.0001 0.6601
standard deviation.
sites did not have significantly more bone loss than mandibular sites (Table 1). Bone loss of mesial sites and molar sites did not differ significantly from distal sites and premolar sites, respectively (Tables 2 and 3). There was no correlation between bone loss score in the 50 patient population and patient age at initial visit, the number of years between radiographie series, or the number of teeth lost during the study. Sex and race also did not affect bone loss scores significantly, although nonwhites had more bone loss than whites (0.032 mm for whites and 0.064 mm for nonwhites). The study population was classified as well-maintained (WM), downhill (D), or extreme downhill (ED) based on the number of teeth lost, as outlined by Hirschfeld and Wasserman,13 McFall,14 and Wood et al.12 In the radiographic sample population 43 patients (86%) were classified as well-maintained, 5 as downhill, and 2 as extreme downhill. The amount of bone loss was not significantly different between the well-maintained and the downhill groups, but the well-maintained group lost a mean of 0.029 mm annually and the downhill group lost 0.085 mm. Of the sample, 30 patients (60%) had been recalled at 6 to 9 month intervals, on average, while 12 patients (24%) were recalled at intervals less than every 6 months, and 8 patients (16%) were recalled at intervals of more than every 9 months. There was no significant difference between bone loss scores of the recall interval groups using the general linear models procedure.
436
ALVEOLAR BONE LOSS AND LONG TERM SUPPORTIVE CARE
Table 4. Comparison of Annual Bone Loss Scores Between Sites Treated Surgically and Nonsurgically Patient
Site
42 43 35
389 362 230
Mean Bone Score*
Surgery
No surgery Difference *in mm,
±
0.048 0.018 -0.028
± ±
±
0.089 0.058 0.087
Value 0.0011 0.0439 0.0619
standard deviation.
Table 5. Comparison of Overall Annual Bone Loss Score and Bone Loss Score Using Abbreviated Index
Patient
Site
50 50
751 317
Mean Bone Score* Overall Abbreviated Difference *in mm,
±
0.037 0.033 0.004
± ±
±
0.061 0.069 0.049
Value 0.0001 0.0013 0.5677
standard deviation.
sites treated surgically and some sites treated without surgery. The difference between the two was not significant (P 0.06); however, sites treated with surgery did tend to have more bone loss (0.048 mm with surgery and 0.018 mm without) (Table 4). Selikowitz et al.3 used an abbreviated index using mandibular sites from the mesial of the second molar to the distal of the first premolar and found no significant difference from total scores. When analyzed in this fashion, our data again show no significant difference from overall mean A total of 35
patients
had
some
=
score
(Table 5).
DISCUSSION The effectiveness of periodontal treatment and long-term supportive care can be evaluated by the presence or absence of continued bone destruction. The annual bone loss score (0.037 mm) represents a mean loss of bone for all 50 patients and should not be interpreted as a slow, continuous rate of destruction on a truly annual basis. This score found in this patient population on recall maintenance in a dental school for an average of 14.9 years compares well to bone loss found in studies of patients treated and maintained in private practice. Selikowitz et al.3 found an annual loss of 0.04 mm in horizontal defects and 0.03 mm in vertical defects. In dental school patients maintained for periods from 4 to 14 years, Rohner et al.4 found approximately 0.07 mm loss annually. Suomi et al.3 found less loss with supportive care (0.003 mm) than without maintenance (0.063 mm), but this study comprised only 3 years of post-treatment monitoring. Cross-sectional studies have also been used to compute annual rates of bone loss. Markkanen et al.15 found a mean 0.06 mm bone loss annually, and Boyle et al.2 found 0.017 mm annual loss in healthy patients. Ramfjord16 has suggested that maintenance care at 2 to 4 month intervals may prevent loss of attachment in treated periodontal patients. Becker et al.1'-17 compared bone loss in patients with good maintenance care with patients who
J Periodontol July 1990
received no maintenance and determined that increased frequency of supportive therapy resulted in decreased bone loss. All patients in the present study received long-term supportive therapy, but only 24% of the patients in the present study were seen at less than 6 month intervals. In this recall program patients are notified and then must call to arrange an appointment. This may result in a more motivated population of subjects. Furthermore, the maintenance appointments generally require 2 to 3 hours to complete, are quite thorough, and are closely evaluated. These factors may have contributed to the minimal loss of bone seen radiographically. In this population, molars did not have more bone loss than premolars. Untreated patients or infrequently maintained patients have been reported to have more bone loss and higher tooth mortality of molars than other teeth."-18 A recent cross-sectional study found more bone loss in maxillary sites, and in men and by age, but not between mesial and distal sites.19 Although not statistically significant, it was noted that nonwhites have more bone loss than whites. Since this study was based entirely on radiographs, the general health status of individual patients is unknown. It has been suggested by Cutress20 and Johnson et al.21 that certain subpopulations are at higher risk for periodontal destruction than others. Based on tooth loss classification,12-14 seven patients in this study were determined to be downhill or extreme downhill. There was no significant difference in amount of bone loss in these patients and the remaining 43 patients, but there was a greater annual rate of bone loss. These patients in the downhill categories may also represent a subset or minority of the population more susceptible to periodontal
disease.13-14-21 Becker al.9-17 demonstrated that there
was a decrease in of bone loss with increased frequency recall; however, these studies compared good maintenance care versus no maintenance. The present study is not a comparison study, since all patients had received periodic supportive care. Many of these patients were treated when osseous resection surgery was frequently used as a method of treatment for periodontal disease. This could explain the loss of crestal bone height in the surgically treated group. Bone loss is increased after periodontal surgery; however, Rohner et al.4 and DeVore et al." found no differences in mean bone loss with different treatment modalities. The difference between surgically and non-surgically treated sites in this study did not reach statistical significance. Furthermore, some patients did show an increase in bone height. This has also been reported in other studies3 and may be due to increased density and not due to a true gain in crestal height. Bite wings were used in this study since they were more readily available in the population. Bone loss measured directly from bite wings is more accurate than from periapical radiographs due to less discrepancy in vertical angulation of the x-ray beam from the perpendicular.22 The limitations of radiographs have been well documented.23-2''
Volume 61 Number 7
In this
LAYPORT, GRECO, McFALL
study,
35% of sites present at both radiographie examinations could not be measured. Selikowitz et al.3 could not measure 51% of sites from 20 patients where both maxillary and mandibular teeth were scored, and 43% when the mandibular teeth only were scored. Studies based on bone loss as a proportion of tooth or root length as measured on periapical radiographs have fewer nonmeasurable sites. "·26 The statistical method of using the patient as the unit of measurement tends to mask bone loss in individual sites, although sample variation is reduced and correlations increase in magnitude using this technique.25 The error of direct measurement was found to be 0.4 mm in this study. The amount of computed bone loss in this population of patients is 0.037 mm annually. This amount is so slight that, by the direct measurements used in this study, it is virtually unmeasurable and from a clinical perspective is insignificant. Further, the measurement error compares well with other studies. Jeffcoat et al.27 found the error of direct measurement of bone levels on bite wings to be 0.55 mm. Rohner et al.4, using the Schei ruler technique on periapicals, had 0 to 1.3 mm of measurement error
with repeated measures. Computerized techniques can reduce the error to nearly 0.15 mm.27-2x Results of this dental school-based population asssessment of alveolar bone loss compare well with other similar reports. The rate of alveolar bone loss in treated and maintained patients is minimal.
Acknowledgment
The authors wish to thank Dr. Ceib tical analysis.
Phillips
for the statis-
REFERENCES 1. Emslie RD. Formal discussion. J Periodont Res 1974; a (Suppl. 14):89. 2. Boyle WD, Via WF, McFall WT, Jr. Radiographic analysis of alveolar crest height and age. J Periodontol 1973; 44:236. 3. Selikowitz HS, Sheiham A, Albert D, Williams GM.Retrospective longitudinal study of the rate of alveolar bone loss in humans using bite-wing radiographs. J Clin Periodontol 1981; 8:431 4. Rohner F, Cimasoni G, Vuagnat P. Longitudinal radlographical study on the rate of alveolar bone loss in patients of a dental school. J Clin Periodontol 1983; 10:643. 5. Suomi JD, West TD, Chang JJ, McClendon BJ. The effect of controlled oral hygiene procedures on the progression of periodontal disease in adults: Radiographic findings. J Periodontol 1971; 42:562. 6. Lindhe J, Nyman, S. Long-term maintenance of patients treated for advanced periodontal disease. J Clin Periodontol 1984: 11:504. 7. Axelsson P, Lindhe J. Effect of controlled oral hygiene procedures on caries and periodontal disease in adults. J Clin Periodontol 1978; 5:133. 8. Axelsson P, Lindhe J. The significance of maintenance care in the treatment of periodontal disease. J Clin Periodontol 1981 ;8:281. 9. Becker W, Berg L, Becker BE. The long-term evaluation of peri-
10. 11.
12.
13. 14. 15.
16. 17.
18.
19.
437
odontal treatment and maintenance in 95 patients. Int J Periodontal Restorative Dent 1984; 4(2) :55. Becker W, Becker B, Berg L. Periodontal treatment without maintenance. ./ Periodontol 1984; 55:505. DeVore CH, Duckworth JE, Beck FM, Hicks MJ, Brumfield FW, Horton JE. Bone loss following periodontal therapy in subjects without frequent periodontal maintenance. J Periodontol, 1986; 57:354. Wood WR, Greco GW, McFall WT. Tooth loss in patients with moderate Periodontitis after treatment and long-term maintenance care. J Periodontol 1989; 60:516. Hirschfeld L, Wasserman B. A long-term survey of tooth loss in 600 treated periodontal patients. J Periodontol 1978; 49:225. McFall WT, Jr. Tooth loss in 100 treated patients with periodontal disease. A long-term study. J Periodontol 1982; 5.3:539. Markkanen H, Rájala M, Knuttilla M, Lammi S. Alveolar bone loss in relation to periodontal treatment need, socioeconomic status and dental health. J Periodontol 1981; 52:99. Ramfjord SP. Maintenance care for treated Periodontitis patients. J Clin Periodontol 1987; 14:433. Becker W, Becker B, Berg L. Periodontal treatment without maintenance: A restrospective study in 44 patients. J Periodontol 1984; 55:505. Becker W, Becker B, Berg L. Bone loss in untreated periodontal disease: A longitudinal study. Int J Periodontal Restorative Dent 1981;
1(1):25. Papapanau PN,
Wennstrom JL, Grondahl K. Periodontal status in relation to age and tooth type. A cross-sectional radiographie study. J Clin Periodontol 1988; 15:469. 20. Cutress TW. Periodontal health and periodontal disease in young people: Global epidemiology. Inter Dent J 1986; 36:146. 21. Johnson NW, Griffiths GS, Wilton JMA, et al. Detection of highrisk groups and individuals for periodontal disease. Evidence for the existance of high-risk groups and individuals and approaches to their detection. J Clin Periodontol 1988; 15:276. 22. Hausmann E, Allen , Christersson L. Methodology of determination of radiographie bone height. / Dent Res 1989; 68(Spec. Is-
sue) 196(Abstr. 113).
23. Theilade J. An evaluation of the reliability of radiographs in the measurement of bone loss in periodontal disease. J Periodontol 1960; 31:143. 24. Rosling B, Hollender L, Nyman S, Olsson G. A radiographie method for assessing changes in alveolar bone height following periodontal therapy. / C///7 Periodontol 1975; 2:211. 25. Duckworth JE, Judy PF, Goodson JM, Socransky SS. A method for the geometric and densiometric standardization of intraoral radiographs. / Periodontol 1983; 54:435. 26. Kelly GP, Cain RJ, Knowles JW, et al. Radiographs in clinical periodontal trials. J Periodontol 1975; 46:381. 27. Jeffcoat MK, Jeffcoat RL, Williams RC. A new method for the comparison of bone loss measurements on non-standardized radiographs. J Periodont Res 1984; 19:434. 28. Allen K, Dunford R, Christersson L, Hausmann E. Reliability of radiographie bone height measurements. J Dent Res 6 1989; 68(Spec.
Issue): 196(Abstr. 114).
Send reprint requests to: Dr. Walter T. McFall, Jr., Department of Periodontics, CB #7450, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450. Accepted for publication January 20, 1990.
Alveolar Bone Loss in Patients with Long-Term Supportive Care *
Cynthia A. Layport, George
W.
Greco,f and
Walter T. McFall, Jr. *
Radiographic record audits were conducted on 63 patients diagnosed as having Periodontitis who had been treated and maintained for 10 years or longer in dental school clinics. Acceptable bite-wing radiographs were available for 50 of these patients. Bitewing radiographs taken 8 to 34 years apart (mean 14.9 years) were assessed for bone loss. Recall maintenance had been accomplished for 60% of these patients at 6 to 9 month intervals, while 24% had been seen more frequently. The mean annual rate of bone loss was 0.037 mm (range of -0.19 to 0.20). There were no significant differences in bone loss between maxillary/mandibular, molar/premolar, or mesial/distal sites respectively. Alveolar bone loss in this dental school population compares well with other reported studies. Progression of disease as assessed by radiographie bone loss in treated and maintained Periodontitis patients is minimal. J Periodontol 1990;61:434-437.
Key
Words:
diography.
Periodontitis/prevention
and
control; periodontitis/diagnosis; bone loss/ra-
Radiographic assessment of alveolar bone loss in patients with Periodontitis can be used as a measure of the progression of disease on a longitudinal basis. It may actually be more reliable than clinical probing measurements over a long period of time.1 Boyle et al.2 reported a reduction of alveolar crest height measured radiographically of only 0.017 mm per year and determined that aging is not a factor in alveolar bone loss, provided periodontal health is maintained. Other reports have indicated that the rate of alveolar loss in patients with periodontal disease ranges between 0.03 mm and 0.07 mm per year.3-:i Maintenance therapy accomplished on a 2 to 4 month basis appears to halt the radiographie evidence of progression in most patients.6-9 Bone loss does occur in patients receiving periodontal treatment without adequate periodontal supportive care.10'" Few studies have utilized bite-wing radiographs, although clinically they are the most commonly used method to estimate bone loss. Selikowitz et al.3 used a 3M reader to measure bone loss on bite-wing radiographs in two private practices. Rohner et al.4 examined a dental school population using the technique described by Schei. The purpose of the present study was to assess the rate of radiographie alveolar bone loss in a group of patients treated and maintained in the predoctoral and graduate clinics of a dental school for a period of 10 or more years. Private Practice of Periodontics, Portland, or.
'Department of Periodontics, Carolina, Chapel Hill, NC.
School of
Dentistry, University
of North
MATERIALS AND METHODS The study population comprised 63 patients who had received treatment for periodontal disease and were then maintained in a dental school clinic for 10 years or longer. Criteria for record audit and clinical findings of these patients have been reported by Wood et al.12 During active treatment all patients received supragingival and subgingival scaling and root planing accompanied by oral hygiene instruction, performed by a predoctoral dental student or periodontal resident. Most patients received surgical therapy which included gingivectomy, flap surgery, flap curettage, osseous contouring, and osseous grafting. Bite-wing radiographs taken at least 8 years apart were available for 50 of these 63 patients. The long cone paralleling technique was used. Radiographs were considered to be acceptable if the cemento-enamel junction (CEJ), margin of a restoration, and interdental crest of bone were clearly visible. Radiographs with overlapping crown images or distorted vertical angulation were not used. If a restoration had been placed between the initial bite-wing radiograph and the final bite-wing radiograph, then these films were not used. Each radiograph was placed in a slide mount and projected onto a screen to achieve 10-fold magnification. An unexposed film with fine lines 1 mm apart was used to standardize the magnification at each reading session. Radiographs were separated so that the initial and final sets from each patient were not read at the same session. The cemento-enamel junction point was chosen as the coronal reference point since it is more reliable than the most occlusal point.3 When the CEJ was not visible due to
Volume 61 Number 7
the presence of a restoration, the most apical point of the restoration was used. The most coronal level of the alveolar bone, where the periodontal space was 0.2 mm when visible, was used as the apical reference point. Measurements were made on the projected images to .01 mm using a Boley gauge 4 The mesial and distal surfaces of the first and second molars and premolars were evaluated, generally with the molars being examined from the molar bite-wing and the premolars from the premolar bite-wing. Missing teeth and the presence of overhanging restorations were also noted. To determine the mean error of measurement, the distance from the coronal reference point to the apical reference point was scored at each site on ten randomly selected bitewings on three different occasions by the principal investigator (C.A.L.). A 2-week interval occurred between each scoring session to reduce bias. The difference between the two most discrepant measurements for each site determined the amount of error for that site. Mean error of measurement was obtained by totaling discrepancy values and dividing by number of sites scored. The mean error of measurement was found to be 0.4 mm. To obtain a measure of bone loss, the readable score for each post-maintenance site was subtracted from the initial bite-wing score for each site. The resultant bone level change was then divided by the number of years between radiographic examinations to achieve an annual bone loss score. The mean scores for each patient were used for statistical analysis using the Statistical Analysis System package.§ RESULTS
Radiographs from 13 of the 63 patients in the study population could not be used. There were no statistical differences in age, sex, recall interval, or maintenance classification between these 13 patients and the 50 patient sample used. At the time of the initial examination, the mean age of the 50 patients was 46.7 years, with a range of 24 to 67 years of age. There were 31 females and 19 males, and Caucasians comprised 84% of the sample. The mean interval between radiographs was 14.9 years, with a range of 8.4 to 34.3 years. Of a possible 1600 surfaces, 290 (145 posterior teeth) were missing at the initial radiographie examination and 150 sites (75 posterior teeth) were lost during the study; 176 sites were not included because the CEJ reference was obliterated by a restoration placed between the two sets of radiographs; 233 sites (20% of those present) could not be evaluated due to obstruction of the CEJ or alveolar crest. Most frequently the mesials of the mandibular first premolars were the sites that could not be accurately evaluated. Bone loss scores were obtained for 751 sites in the 50 patients. The average number of readable sites was 15 with a range of 4 to 30. The mean annual rate of bone loss for all patients was 0.037 mm (range -0.19 to 0.20). Maxil*MiItex Instruments, Lake Success, NY. §SAS Institute, Inc., Cary, NC.
LAYPORT, GRECO, Comparison of Annual Bone Maxillary and Mandibular Sites Table 1.
Patient
Site
49 50
375 376
McFALL
Loss Scores Between
Mean Bone Score*
Maxillary
Mandibular Difference *in mm,
±
435
0.045 ± 0.087 0.029 ± 0.065 0.017 ± 0.085
Value 0.0006 0.0023 0.1698
standard deviation.
Table 2. Comparison of Annual Bone Loss Scores Between Molar and Premolar Sites
Molar Premolar Difference *in mm,
±
Patient
Site
47
320 431
50
Mean Bone Score* 0.046 ± 0.075 0.036 ± 0.060 0.008 ± 0.055
Value 0.0001 0.0001 0.2886
standard deviation.
Table 3. Comparison of Annual Bone Loss Scores Between Mesial and Distal Sites
Mesial Distal Difference *in mm,
lary
±
Patient
Site
50 50
369 382
Mean Bone Score* 0.036 ± 0.067 0.039 ± 0.064 -0.003 ± 0.054
Value 0.0004 0.0001 0.6601
standard deviation.
sites did not have significantly more bone loss than mandibular sites (Table 1). Bone loss of mesial sites and molar sites did not differ significantly from distal sites and premolar sites, respectively (Tables 2 and 3). There was no correlation between bone loss score in the 50 patient population and patient age at initial visit, the number of years between radiographie series, or the number of teeth lost during the study. Sex and race also did not affect bone loss scores significantly, although nonwhites had more bone loss than whites (0.032 mm for whites and 0.064 mm for nonwhites). The study population was classified as well-maintained (WM), downhill (D), or extreme downhill (ED) based on the number of teeth lost, as outlined by Hirschfeld and Wasserman,13 McFall,14 and Wood et al.12 In the radiographic sample population 43 patients (86%) were classified as well-maintained, 5 as downhill, and 2 as extreme downhill. The amount of bone loss was not significantly different between the well-maintained and the downhill groups, but the well-maintained group lost a mean of 0.029 mm annually and the downhill group lost 0.085 mm. Of the sample, 30 patients (60%) had been recalled at 6 to 9 month intervals, on average, while 12 patients (24%) were recalled at intervals less than every 6 months, and 8 patients (16%) were recalled at intervals of more than every 9 months. There was no significant difference between bone loss scores of the recall interval groups using the general linear models procedure.
436
ALVEOLAR BONE LOSS AND LONG TERM SUPPORTIVE CARE
Table 4. Comparison of Annual Bone Loss Scores Between Sites Treated Surgically and Nonsurgically Patient
Site
42 43 35
389 362 230
Mean Bone Score*
Surgery
No surgery Difference *in mm,
±
0.048 0.018 -0.028
± ±
±
0.089 0.058 0.087
Value 0.0011 0.0439 0.0619
standard deviation.
Table 5. Comparison of Overall Annual Bone Loss Score and Bone Loss Score Using Abbreviated Index
Patient
Site
50 50
751 317
Mean Bone Score* Overall Abbreviated Difference *in mm,
±
0.037 0.033 0.004
± ±
±
0.061 0.069 0.049
Value 0.0001 0.0013 0.5677
standard deviation.
sites treated surgically and some sites treated without surgery. The difference between the two was not significant (P 0.06); however, sites treated with surgery did tend to have more bone loss (0.048 mm with surgery and 0.018 mm without) (Table 4). Selikowitz et al.3 used an abbreviated index using mandibular sites from the mesial of the second molar to the distal of the first premolar and found no significant difference from total scores. When analyzed in this fashion, our data again show no significant difference from overall mean A total of 35
patients
had
some
=
score
(Table 5).
DISCUSSION The effectiveness of periodontal treatment and long-term supportive care can be evaluated by the presence or absence of continued bone destruction. The annual bone loss score (0.037 mm) represents a mean loss of bone for all 50 patients and should not be interpreted as a slow, continuous rate of destruction on a truly annual basis. This score found in this patient population on recall maintenance in a dental school for an average of 14.9 years compares well to bone loss found in studies of patients treated and maintained in private practice. Selikowitz et al.3 found an annual loss of 0.04 mm in horizontal defects and 0.03 mm in vertical defects. In dental school patients maintained for periods from 4 to 14 years, Rohner et al.4 found approximately 0.07 mm loss annually. Suomi et al.3 found less loss with supportive care (0.003 mm) than without maintenance (0.063 mm), but this study comprised only 3 years of post-treatment monitoring. Cross-sectional studies have also been used to compute annual rates of bone loss. Markkanen et al.15 found a mean 0.06 mm bone loss annually, and Boyle et al.2 found 0.017 mm annual loss in healthy patients. Ramfjord16 has suggested that maintenance care at 2 to 4 month intervals may prevent loss of attachment in treated periodontal patients. Becker et al.1'-17 compared bone loss in patients with good maintenance care with patients who
J Periodontol July 1990
received no maintenance and determined that increased frequency of supportive therapy resulted in decreased bone loss. All patients in the present study received long-term supportive therapy, but only 24% of the patients in the present study were seen at less than 6 month intervals. In this recall program patients are notified and then must call to arrange an appointment. This may result in a more motivated population of subjects. Furthermore, the maintenance appointments generally require 2 to 3 hours to complete, are quite thorough, and are closely evaluated. These factors may have contributed to the minimal loss of bone seen radiographically. In this population, molars did not have more bone loss than premolars. Untreated patients or infrequently maintained patients have been reported to have more bone loss and higher tooth mortality of molars than other teeth."-18 A recent cross-sectional study found more bone loss in maxillary sites, and in men and by age, but not between mesial and distal sites.19 Although not statistically significant, it was noted that nonwhites have more bone loss than whites. Since this study was based entirely on radiographs, the general health status of individual patients is unknown. It has been suggested by Cutress20 and Johnson et al.21 that certain subpopulations are at higher risk for periodontal destruction than others. Based on tooth loss classification,12-14 seven patients in this study were determined to be downhill or extreme downhill. There was no significant difference in amount of bone loss in these patients and the remaining 43 patients, but there was a greater annual rate of bone loss. These patients in the downhill categories may also represent a subset or minority of the population more susceptible to periodontal
disease.13-14-21 Becker al.9-17 demonstrated that there
was a decrease in of bone loss with increased frequency recall; however, these studies compared good maintenance care versus no maintenance. The present study is not a comparison study, since all patients had received periodic supportive care. Many of these patients were treated when osseous resection surgery was frequently used as a method of treatment for periodontal disease. This could explain the loss of crestal bone height in the surgically treated group. Bone loss is increased after periodontal surgery; however, Rohner et al.4 and DeVore et al." found no differences in mean bone loss with different treatment modalities. The difference between surgically and non-surgically treated sites in this study did not reach statistical significance. Furthermore, some patients did show an increase in bone height. This has also been reported in other studies3 and may be due to increased density and not due to a true gain in crestal height. Bite wings were used in this study since they were more readily available in the population. Bone loss measured directly from bite wings is more accurate than from periapical radiographs due to less discrepancy in vertical angulation of the x-ray beam from the perpendicular.22 The limitations of radiographs have been well documented.23-2''
Volume 61 Number 7
In this
LAYPORT, GRECO, McFALL
study,
35% of sites present at both radiographie examinations could not be measured. Selikowitz et al.3 could not measure 51% of sites from 20 patients where both maxillary and mandibular teeth were scored, and 43% when the mandibular teeth only were scored. Studies based on bone loss as a proportion of tooth or root length as measured on periapical radiographs have fewer nonmeasurable sites. "·26 The statistical method of using the patient as the unit of measurement tends to mask bone loss in individual sites, although sample variation is reduced and correlations increase in magnitude using this technique.25 The error of direct measurement was found to be 0.4 mm in this study. The amount of computed bone loss in this population of patients is 0.037 mm annually. This amount is so slight that, by the direct measurements used in this study, it is virtually unmeasurable and from a clinical perspective is insignificant. Further, the measurement error compares well with other studies. Jeffcoat et al.27 found the error of direct measurement of bone levels on bite wings to be 0.55 mm. Rohner et al.4, using the Schei ruler technique on periapicals, had 0 to 1.3 mm of measurement error
with repeated measures. Computerized techniques can reduce the error to nearly 0.15 mm.27-2x Results of this dental school-based population asssessment of alveolar bone loss compare well with other similar reports. The rate of alveolar bone loss in treated and maintained patients is minimal.
Acknowledgment
The authors wish to thank Dr. Ceib tical analysis.
Phillips
for the statis-
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Send reprint requests to: Dr. Walter T. McFall, Jr., Department of Periodontics, CB #7450, School of Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450. Accepted for publication January 20, 1990.
