Temporomandibular disorders (TMDs) is a collective term that embraces a variety of temporomandibular joint (TMJ) disorders, masticatory muscle disorders, headache disorders, and disorders affecting the associated structures [
It is generally believed that a variety of biological, psychological, and social factors may reduce the adaptive capacity of the masticatory system, thus resulting in TMDs [
This investigation was designed as a cross-sectional, population-based study. During three subsequent semesters, participants were drawn from among adolescents attending nine Dutch secondary schools that were willing to participate in this investigation. Because of time demand or other priorities at that time, 23 schools declined participation. All approached schools were dispersed over the southern and western parts of Netherlands and were situated in urban areas. Prior to the data collection, the parents/legal representatives received an information letter about the study. The children and/or the parents/legal representatives had the right to refuse participation.
On the day of data collection, a questionnaire was handed over to the schools’ pupils and collected several minutes later, before the lessons started. This questionnaire contained 17 items that covered demographic items, sleep and awake bruxism, signs and symptoms of TMDs, and psychosocial and behavioural factors [
Orofacial pain, indicative of TMD pain, was assessed by means of the following question: “Have you had pain in the face, jaw, temple, in front of the ear or in the ear?” (no, yes). The question referred to the presence of pain within the last month. The presence of TMJ sounds was assessed using the question “Does your jaw make a clicking or popping sound when you open or close your mouth, or while chewing?” (no, yes). The question referred to the presence of TMJ sounds within the last month.
Since no clinical diagnoses were established in this study, the term “pain-related TMDs” has to be interpreted as “pains indicative of TMD pain” and “TMJ sounds” as “self-perceived TMJ sounds.”
Age (years) and sex (0, “male”; 1, “female”). The presence of sleep bruxism was assessed using the question “Have you been told, or did you notice yourself, that you grind your teeth or clench your jaws when you are asleep?” The presence of awake bruxism was assessed using the question “Do you grind your teeth or clench your jaws during the day?” These questions referred to the last month, and the pupils could choose between no, yes, or unknown. Other oral activities that may be stressful to the masticatory system were asked by the following four questions: Do you chew on chewing gum? Do you bite your nails? Do you bite on pens/pencils? Do you bite your lips/cheeks? Again, these questions referred to the last month, and the answer possibilities were no, occasionally, regularly, often, and very often. The following exogenous aspects were assessed: “Do you smoke cigarettes?” and “Do you drink alcohol?” (both questions: no, occasionally, regularly, often, and very often).
An impression of the psychological status was assessed by means of the following two questions “Are you stressed?” and “Are you feeling sad?” (both questions referred to the last month: no, occasionally, regularly, often, and very often).
Ethnic background was classified following the method of Statistics Netherlands (CBS), using the country of birth from both parents. This procedure resulted in a classification into two subgroups, namely, native Dutch (i.e., both parents were born in Netherlands, regardless of the country of birth of the subject; coded “0”) and nonnative Dutch (i.e., all other subjects; coded “1”). Educational level was characterized by the type of the secondary educational system that was followed. Depending on their abilities, Dutch children around the age of 12 can choose for either vmbo, vmbo/havo, havo, havo/vwo, or vwo. The vmbo diploma gives access to advanced vocational education, the havo diploma to polytechnic education, and the vwo diploma to university education. The 5-point Likert scale item educational level was recoded into a dichotomous variable (vwo (1) versus the other levels (0)).
Descriptive statistics included frequency distributions of each of the independent variables. In order to determine the prevalence rates of TMD pain and TMJ sounds, the prevalence data were stratified by gender and age and ratios were calculated. The chi-square test was performed to test the association between TMD pain and TMJ sounds as depicted in a 2 × 2 contingency table. To determine the association between the outcome variables and each of the independent variables, hierarchical logistic regression analyses were performed. First, single regression analyses were executed to determine the associations between each of the various predictors and the outcome variable. Regarding the ordinal variables, initial analyses were based on the full range of the 5-point Likert response options, and linearity of their effect on the presence of TMD pain was checked by analysis of dummy variables. When the regression coefficients of the dummy variables consistently increased or decreased, linearity was considered present. In case of a nonlinear association, the variable was dichotomized. Second, independent variables that showed at least a moderate association with the outcome measure were entered in a multiple regression model. Due to the fact that the large sample size may impact the corresponding
Initially, a total of 4,285 pupils, with ages ranging from 10 to 22 years, completed the questionnaire. Since the present study focuses on TMD pain during adolescence, the data of pupils under twelve years (children) and above eighteen years (adults) were excluded (
Descriptive statistics of the predictor variables.
Independent variable | |
---|---|
Age (years) | 14.5 (±1.6) |
Gender | |
Male | 1,974 (50.1%) |
Female | 1,966 (49.9%) |
Sleep bruxism | |
No | 2,874 (82.0%) |
Yes | 633 (18.0%) |
Awake bruxism | |
No | 3,334 (90.0%) |
Yes | 372 (10.0%) |
Chewing gum | |
No | 261 (6.2%) |
Yes | 3,943 (93.8%) |
Biting nails | |
No | 2,105 (50.0%) |
Yes | 2,104 (50.0%) |
Biting pens and pencils | |
No | 2,397 (56.9%) |
Yes | 1,819 (43.1%) |
Biting lips and/or cheeks | |
No | 1,793 (42.6%) |
Yes | 2,414 (57.4%) |
Smoking cigarettes | |
No | 3,658 (86.7%) |
Yes | 559 (13.3%) |
Alcohol consumption | |
No | 2,166 (51.4%) |
Yes | 2,046 (48.6%) |
Being stressed | |
No | 1,680 (39.9%) |
Yes | 2,534 (60.1%) |
Feeling sad | |
No | 2,183 (51.8%) |
Yes | 2,030 (48.2%) |
School type | |
Lower levels | 2,386 (56.3%) |
Highest level | 1,849 (43.7%) |
Ethnic background | |
Native Dutch | 3,368 (82.0%) |
Nonnative Dutch | 740 (18.0%) |
The dichotomized categorical variables are presented as absolute numbers (ratio); age is presented as mean value (±standard deviation).
Of the 3,935 adolescents who completed the questions about gender and TMDs, the overall prevalence of pain-related TMDs was 21.6% (26.1% for girls and 17.6% for boys). The overall prevalence of TMJ sounds was 15.5% (
Age- and gender-specific prevalence of TMD pain (a) and TMJ sounds (b) among Dutch adolescents.
In order to find out which biological, psychological, or social factors had the strongest association with the presence of pain-related TMDs, logistic regression analyses were performed. In the first step, all variables were entered consecutively in a single regression model in order to determine their unadjusted association with the TMD pain. Regarding the included 5-point ordinal variables, inspection of the regression coefficients of the dummy variables revealed that perfect linearity of their effect on the presence of TMD pain was present only for the predictor “biting lips and/or cheeks.” All ordinal variables were therefore dichotomized (no = 0; all other categories = 1). Table
Single and multiple logistic regression models for the prediction of TMD pain among Dutch adolescents.
Single regression | P-to-Exit | Multiple regression ( |
||||||
---|---|---|---|---|---|---|---|---|
|
|
OR | 95% CI |
|
OR | 95% CI | ||
Biological items | ||||||||
Female gender | 1,964 | <0.001 | 1.66 | 1.42–1.94 | 0.008 | 1.29 | 1.07–1.55 | |
Age (years) | 4,106 | <0.001 | 1.12 | 1.06–1.17 | <0.001 | 1.11 | 1.05–1.17 | |
Smoking cigarettes (positive) | 559 | <0.001 | 1.60 | 1.31–1.95 | 0.467 | — | — | — |
Drinking alcohol (positive) | 2,044 | <0.001 | 1.49 | 1.29–1.73 | 0.097 | — | — | — |
Sleep bruxism (positive) | 631 | <0.001 | 1.76 | 1.45–2.14 | <0.001 | 1.60 | 1.29–1.98 | |
Awake bruxism (positive) | 372 | <0.001 | 1.93 | 1.53–2.44 | 0.262 | — | — | — |
Chewing gum (positive) | 3,938 | n.s. | 1.00 | 0.74–1.36 | ||||
Biting nails (positive) | 2,100 | n.s. | 0.95 | 0.82–1.10 | ||||
Biting pencils (positive) | 1,816 | <0.001 | 1.34 | 1.16–1.55 | 0.435 | — | — | — |
Biting lips and/or cheeks (positive) | 2,409 | <0.001 | 1.69 | 1.45–1.97 | 0.003 | 1.33 | 1.10–1.61 | |
Psychological items | ||||||||
Being stressed (positive) | 1,679 | <0.001 | 2.33 | 1.97–2.74 | <0.001 | 1.60 | 1.28–1.99 | |
Feeling sad (positive) | 2,025 | <0.001 | 2.14 | 1.84–2.48 | <0.001 | 1.55 | 1.27–1.88 | |
Social items | ||||||||
Non-Dutch ethnicity | 738 | n.s. | 0.97 | 0.80–1.18 | ||||
Highest educational level | 1,848 | n.s. | 1.03 | 0.88–1.19 |
Associations are expressed as odds ratio (OR) and 95% confidence interval (CI). For each removed predictor variable, the P-to-Exit is reported; n.s. = not significant. Significance levels are 0.05 and 0.01, respectively.
Table
Single and multiple logistic regression models for the prediction of TMJ sounds among Dutch adolescents.
Single regression | P-to-Exit | Multiple regression ( |
||||||
---|---|---|---|---|---|---|---|---|
|
|
OR | 95% CI |
|
OR | 95% CI | ||
Biological items | ||||||||
Female gender | 1,959 | <0.001 | 1.81 | 1.51–2.16 | <0.001 | 1.77 | 1.45–2.16 | |
Age (years) | 4,090 | <0.001 | 1.19 | 1.13–1.26 | <0.001 | 1.21 | 1.14–1.29 | |
Smoking cigarettes (positive) | 557 | <0.001 | 1.55 | 1.23–1.94 | 0.156 | — | — | — |
Drinking alcohol (positive) | 2,040 | <0.001 | 1.53 | 1.29–1.82 | 0.406 | — | — | — |
Sleep bruxism (positive) | 633 | <0.001 | 1.62 | 1.30–2.02 | 0.045 | — | — | — |
Awake bruxism (positive) | 369 | <0.001 | 1.98 | 1.53–2.56 | 0.262 | <0.001 | 1.79 | 1.36–2.36 |
Chewing gum (positive) | 3,922 | 0.046 | 1.50 | 1.01–2.22 | 0.011 | — | — | — |
Biting nails (positive) | 2,093 | n.s. | 1.14 | 0.96–1.34 | ||||
Biting pencils (positive) | 1,811 | n.s. | 1.34 | 0.96–1.35 | 0.435 | — | — | — |
Biting lips and/or cheeks (positive) | 2,406 | <0.001 | 1.66 | 1.39–1.98 | <0.001 | 1.46 | 1.19–1.80 | |
Psychological items | ||||||||
Being stressed (positive) | 1,668 | <0.001 | 1.81 | 1.50–2.17 | 0.042 | — | — | — |
Feeling sad (positive) | 2,019 | 0.001 | 1.31 | 1.12–1.56 | 0.123 | — | — | — |
Social items | ||||||||
Non-Dutch ethnicity | 732 | n.s. | 0.81 | 0.64–1.02 | ||||
Highest educational level | 1,846 | n.s. | 0.86 | 0.73–1.02 |
Associations are expressed as odds ratio (OR) and 95% confidence interval (CI). For each removed predictor variable, the P-to-Exit is reported; n.s. = not significant. Significance levels are 0.05 and 0.01, respectively.
The present questionnaire study aimed to assess the prevalence rates of two categories of temporomandibular disorders (TMDs), namely, pain-related manifestations of TMDs and TMJ sounds, in a large group of Dutch adolescents aged between 12 and 18 years. In addition, we examined which biological, psychological, or social risk indicators were associated with them and if both categories of TMDs yielded similar risk indicators. The results demonstrated that self-reported TMD pain is relatively common among 12- to 18-year-old Dutch adolescents, with an overall prevalence of about 20%. Besides the fact that the occurrence of TMD pain was highly associated with that of TMJ sounds, this pain was correlated to female gender, increasing age, reports of sleep bruxism, biting on lips and/or cheeks, stress, and feeling sad. The overall prevalence of TMJ sounds was about 15%; female gender, increasing age, awake bruxism, and biting on lips and/or cheeks were the best predictors. Except for the psychological factors that appeared to be associated with TMD pain only, pain-related TMDs and TMJ sounds shared similar biological risk indicators.
It is generally acknowledged that depending on the study, the prevalence of TMD pain in children and adolescents varies widely [
Regarding the role of biological risk indicators on pain-related forms of TMDs, we demonstrated that the prevalence of TMD pain increases with increasing age in the period of adolescence. This is in line with several other studies (e.g., [
Based on the present findings, it appeared that the two included psychological factors (namely, being stressed and feeling sad) contributed significantly to the presence of TMD pain among adolescents. Again, this is not surprising as both factors are frequently mentioned in relation to this pain (e.g., [
Finally, the social factors ethnic background and educational level were not associated with the presence of TMD pain. The negative findings in this study might show that differences in ethnicity and educational level in Dutch adolescents do not necessarily represent different social environments in relation to the report of pain. Out of a vast range of social factors that have been considered to influence an individual’s pain behaviour, parent emotions, behaviours, and health seem to play an important role in a child’s pain experience [
The overall prevalence of self-reported TMJ sounds was 15.5%, which is in line with approximately 14% as reported in a recent meta-analysis on the prevalence of TMJ sounds (click or crepitation) in children and adolescents [
As for TMD pain, four biological factors appeared to be associated with TMJ sounds. Consistent with other studies on the young population, the prevalence of TMJ sounds increased considerably with age [
This study has several limitations. First of all, pain-related TMDs and TMJ sounds were obtained by a questionnaire with no objective confirmation of signs and symptoms, thus being at risk of recall bias. However, high validity can exist between self-reported pain questions and the outcome of a clinical examination in adolescents [
This study indicates that both pain-related manifestations of TMDs and TMJ sounds are a common finding in the adolescent population. Both categories share similar biological risk indicators, whereas psychological factors were only associated with pain-related TMDs.
All relevant data are within the paper. On request, the data sets generated and/or analyzed during the current study are available from the corresponding author.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
The authors would like to thank the participating schools for their willingness to invest time and effort in this study. The authors would especially like to acknowledge the following dental students, bachelor students at the time, for their contributions: M. D. Kwehandjaja, R. N. van Minnen, F. K. M. ten Berge, E. M. de Bakker, L. M. M. Kes, I. A. M. Veerman, M. Hessling, and F. Peereboom. The study was partly funded by Trisakti University and Gesere Foundation, a private foundation to support young scientists from North Sumatra, Indonesia.