Journal of Oral Rehabilitation. 1990, Volume 18, pages 243-251

Aetiological factors of craniomandibular disorders in completely edentulous denture-wearing patients K . D . B . F A U L K N E R an J M . D . F . M E R C A D O Faculty of Medicine and Dentistry, School of Dental Science. University of Melbotane, Melbourne, Victoria, Australia

Summary

A total of 201 completely edentulous patients awaiting treatment for new complete dentures at the Royal Dental Hospital of Melbourne were examined for signs and symptoms of craniomandibular disorders, and a history was taken regarding their dentures. Statistical analysis by means of Student's r-tcst showed that the only reliable indicator of craniomandibular disorder was the patient's sex., i.e. female subjects tend to show more symptoms of craniomandibular disorders than male subjects. When regression and multiple regression analyses were applied, it was found that subjects with a history of fewer sets of complete dentures worn appeared to be correlated with an increase in the number of signs and symptoms of craniomandibular disorders. However, this correlation had a weak predictive power, although it was significant enough to indicate that such a relationship could exist in the general population. Introduction

The prevalence of craniomandibular disorders (CMD) has been known to occur to varying degrees in different populations (Helkimo, 1974a, 1974b, 1974c; Choy & Smith, 1980; Hansen & Axinn, 1984; Agerberg, 1988). The extent of its prevalence among completely edentulous denture-wearing subjects, while thought to be high, is still not clearly established (Franks, 1967; Loiselle, 1969; MacEntee et al, f987). This may be due to differences in methods of examination, criteria for diagnosis and selection of samples (Agerberg & Helkimo, 1987). Because of their impaired oral capacity, completely edentulous denture-wearing subjects have been studied in relation to the clinical aspects of masticatory function (Atkinson & Ralph, 1973). The temporomandibular joint (TMJ) and its related structures are an integral part of the masticatory system, which may also be affected by the changes that accompany the complete loss of teeth and subsequent prosthetic rehabilitation (Carlsson, 1984). The aim of this study was to investigate the possible aetiological factors of craniomandibular disorders among completely edentulous denture-wearing patients, by means of a dental history and an anamnestic and clinical evaluation. Materials and methods

A survey was conducted among 201 patients awaiting complete denture treatment with the Victorian Denture Scheme (VDS)\ * The Victorian Denture Scheme (VDS) is a Victorian State Government Funding project administered by the Royal Dental Hospital of Melbourne for provision of complete dentures for edentulous subjects. Correspondence; Dr K. Faulkner, Royal Dental Hospital of Melbourne, 711 Elizabeth Street, Melbourne 3000, Victoria, Australia. 243

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K.D.B. Faulkner and M.D.F. Mercado

Each patient's general and denture history was taken, followed by an anamnestic and clinical examination of the present denture and the patient's experience of signs and symptoms of CMD. Information obtained from the clinical and anamnestic examinations has been reported previously (Mercado & Faulkner, 1990). Results

The information obtained from the general and denture history provided a list of the possible aetiological factors of CMD. These factors were termed CMD indicators, and each indicator was divided into two distinct groups in order to obtain two independent samples for each particular indicator variable. Student's /-test was applied to determine whether any significant relationships existed between the signs and symptoms of CMD and their indicators. The craniomandibular disorder value (CMD value) for each subject who participated in the study was compared with their various CMD indicator variables. The grouping of the CMD indicators and the results of the Student's /-test are shown in Table 1. Other CMD indicators, such as the number of sets of complete dentures and the patient's marital status had more than two independent samples, and an analysis of variance was therefore used to test the mean CMD values so as to obtain a level of significance for these relationships (Table 2). In general, it can be seen that the levels of significance for all the variables are low, and the only CMD indicator that can be interpreted as statistically significant is the patient's sex (P 15 4 15

0-11

Age of present complete dentures (years)

0-5

>5

411

4-02

0-90

0-09

-1-22.

1-40

Denture sleeping habits

did not remove 3-79

removed at least one 4-28

0-22

-0-49

-1-26,

0 28

2-4 4-09

>4 3-39

0-70

0-16

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coincidental 4-09

0-56

-0-25

-1-14.

0-64

Retention and stability of upper denture

poor 3-71

adequate 412

0-37

-0-41

-1-33,

0-51

Retention and stability of lower denture

poor 4-08

adequate 3-69

0-51

0-39

-0-75,

1-53

female

male 3-31

0-02

0-96

0-08.

1-84

Interocclusal distance or freeway space (FWS) (mm) Centric occlusion-centric relation coincidence

-0-62. 0-92

no

Patient's sex

4-27

A 95% confidence interval was selected as an indication of precision so that there is 95% certainty that the true value of the differences between means lies within this interval.

Table 2. Results of the analysis of variance for predictor variables having more than two groups, with the mean CMD scores and the corresponding level of significance Mean CMD values

Predictor variable

Number of sets of complete dentures

1-2 sets 3-61

Patient's marital status

married 3-99

> 5 sets

3-5 sets 4-22 widowed 4-27

Level of signifieance

single 3 60

409

0-23

divorced 4-17

0-78

246

K.D.B. Faulkner and M.D.F. Mercado Plot of CMD with number of sets of dentures

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Fig. 1. Ciraphical presentation of thc regression analysis comparing the number of sets of complete dentures and thc total C MD value. The numbers inside thc graph represent thc number of patients whose sets of dentures arc quantified along the x-axis; 198 cases plotted; A = 10. B = l l .

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Fig. 2. Graphical presentation of the regression analysis comparing the number of years of complete denture experience and thc total CMD value; 198 cases plotted.

Craniomandibular disorders in edentulous patients

247

Plot of CMD with age of present dentures

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24 30 36 42 Age of present dentures

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Fig. 3. Graphical presentation of the regression analysis comparing the age of the present dentures and the total CMD value; 198 cases plotted.

Table 3. Summary of the regression analysis for testing of independent predictor variables taken as an ungrouped sample against the total CMD values, with the correspondmg level of significance and R-square value Independent variable

Duration of complete denture experience (years) Age of present complete dentures (years) Number of sets of complete dentures

Coefficient

Standard error

Level of significance

R-square value

0-076

0-014

0-3

0-0(J628

-0-013

0-018

0-5

0-00279

0-280

0-11^

0-0189

0-02779

CMD score could not be said to exist in the population, i.e. there is no significant correlation between the age of the patient and the number of sets of complete dentures. Discussion

The aim of this study was to investigate the relationships between the signs and

248

K.D.B. Faulkner and M.D.F. Mercado

Table 4. Correlation coefficient between the patient's age and the number of sets of complete dentures Independent variable

Number of sets of complete dentures

Coefficient

Standard error

Level of significance

0-297

0-114

0-01

-0-092

0-023

0-0001

R-square value

0-10042 Patient's age

Table 5. Pearson correlation coefficients between the patient's age and the number of sets of complete dentures

Patient's age

Number of sets of complete dentures

Age

Number of sets of complete dentures

f-(XXX)

0-0340 (201) F-0-316

0-0340 (201) P-0-316

f-OO(X}

symptoms of CMD and their possible aetiology in complete denture wearers. As reported earlier (Mercado & Faulkner, 1990), there was a high prevalence of the signs and symptoms of CMD and, of the 198 statistically valid cases, only 13 subjects (6-6% of this sample) showed no signs or symptoms of CMD. Furthermore, it was found that 15-2% of the valid samples had only one sign or symptom of CMD. The entire sample presented a cumulative frequency of 93-3% having signs and/or symptoms of CMD. These data are in marked contrast with the findings of Loiselle (1969), who concluded that CMD dysfunction in complete denture wearers was rare. However, MacEntee et al. (1987) and Bergman and Carlsson (1972) reported signs and symptoms of mandibular dysfunction in 25% of complete denture wearers studied, while Franks (1967) described a 15% prevalence in 52 complete denture wearers. In 1975, Meyerowitz reported painful muscles of mastication in 59% of complete denture wearing subjects, while McCarthy and Knazan (1987) reported a 68% prevalence of signs and symptom's of mandibular dysfunction. While these figures only support the findings of the present study in part, it is possible that the discrepancies may be due to the differing criteria used to assess the presence or absence of mandibular dysfunction. However, after applying a Student's /-test, it appeared that no significant relationship could be detected between the CMD value and any of the CMD indicators, except for the patient's sex (Table 1). It was shown that female subjects in the population studied had a higher CMD score value than male subjects at a P