TMD in class III patients referred for orthognathic surgery: Psychological and dentition-related aspects

ObjectiveTo investigate temporomandibular disorders (TMD), psychosocial, and occlusal variables in class III orthognathic surgery patients with respect to the control subjects, and to compare psychosocial and occlusal features in class III patients with different Research Diagnostic Criteria for TMD (RDC/TMD) diagnoses.Materials and methodsThe study enrolled 44 class III patients referred for orthognathic surgery and 44 individuals without a malocclusion. TMD, depression and somatization were assessed by RDC/TMD. Occlusal analysis included Helkimo's Occlusal Index items, overjet and overbite.ResultsIn the controls, patients with class III deformities had higher prevalence of myogenic TMD, increased grade of chronic pain, and more occlusal deviations. Within the study group, TMD patients reported higher depression score (P < 0.01), myofascial pain was related to higher depression and somatization grades (P < 0.01, P < 0.05 respectively), and disc displacement showed relation with RCP-ICP slide interferences (P < 0.05).ConclusionWith respect to subjects without a malocclusion, TMD in class III dentofacial deformities is similar in prevalence, but differs in clinical appearance. Occlusal, but not psychosocial features deviate from those in the controls. While psychosocial variables accompanied TMD and myofascial pain, increased RCP-ICP slide was related to disc displacement in class III patients.     

咬合干扰与颞下颌关节紊乱病的相关性研究

目的:通过临床检查分析安氏Ⅱ类1分类颞下颌关节紊乱(temporomandibular disorders,TMD)患者的咬合特点,探讨咬合干扰与颞下颌关节紊乱的相关性。方法:选取安氏Ⅱ类1分类TMD患者60例为实验组,无TMD安氏Ⅱ类1分类患者60例为对照组。采用目前国际上通用的视觉模拟尺分级评分测量法(visual analog scale VAS)对口面部不舒适程度进行评价;按照Fricton指数所包括的内容计算颞下颌功能障碍指数(temporomandibular dysfunction index DI),[DI=(MM+JN+JP)/26(0~1)],该指数包括下颌运动(MM)、关节杂音(JN)及关节压诊(JP)等。结果:实验组有咬合干扰者45例,对照组有咬合干扰者42例,二组间差异无显著性(P>0.05);实验组中存在咬合干扰的患者与无咬合干扰患者相比较,DI指数以及疼痛相关视觉模拟分数(VAS)均偏高,二者间差异有统计学意义(P<0.01),其中女性患者DI指数高于男性。结论:咬合干扰(occlusal interferences,OI)与TMD虽无直接联系,但OI与TMD共存可加重TMD患者临床症状,OI的存在对口颌系统的健康可能构成威胁。     

Soft versus hard occlusal splint therapy in the management of temporomandibular disorders (TMDs)

Aim

To compare between soft and hard occlusal splint therapy for the management of myofacial pain dysfunction (MPD) or internal derangement (ID) of the temporomandibular joint (TMJ) with reciprocal clicking.

Patients and methods

This study included 50 patients (age range: 24–47 years) who had been diagnosed with MPD or ID of the TMJ in the form of reciprocal clicking. Patients were divided into two groups. They were treated for 4 months with either a vacuum-formed soft occlusal splint constructed from 2-mm-thick elastic rubber sheets (soft splint group) or a hard flat occlusal splint fabricated from transparent acrylic resin (hard splint group). Monthly follow-up visits were performed during the treatment period. Before treatment and 1, 2, 3 and 4 months after treatment, the dentist measured all parameters of TMJ function (pain visual analog scores, tenderness of masticatory muscles, clicking and tenderness of the TMJ, and range of mouth opening).

Results

All parameters of TMJ function showed significant improvement in both groups during the follow-up period, with a statistically significant difference between the two groups at the 4-month follow-up visit.

Conclusions

Both forms of occlusal splints (soft and hard) improved TMJ symptoms in patients with MPD or ID of the TMJ. However, the soft occlusal splints exhibited superior results after 4 months of use.     

Women with more severe degrees of temporomandibular disorder exhibit an increase in temperature over the temporomandibular joint

Aim

The purpose of the present study was to correlate the degree of temporomandibular disorder (TMD) severity and skin temperatures over the temporomandibular joint (TMJ) and masseter and anterior temporalis muscles.

Materials and methods

This blind cross-sectional study involved 60 women aged 18–40 years. The volunteers were allocated to groups based on Fonseca anamnestic index (FAI) score: no TMD, mild TMD, moderate TMD, and severe TMD (n = 15 each). All volunteers underwent infrared thermography for the determination of skin temperatures over the TMJ, masseter and anterior temporalis muscles. The Shapiro–Wilk test was used to determine the normality of the data. The Kruskal–Wallis test, followed by Dunn’s test, was used for comparisons among groups according to TMD severity. Spearman’s correlation coefficients were calculated to determine the strength of associations among variables.

Results

Weak, positive, significant associations were found between FAI score and skin temperatures over the left TMJ (rs = 0.195, p = 0.009) and right TMJ (rs = 0.238, p = 0.001). Temperatures over the right and left TMJ were significantly higher in groups with more severe TMD (p < 0.05).

Conclusion

FAI score was associated with skin temperature over the TMJ, as determined by infrared thermography, in this sample. Women with more severe TMD demonstrated a bilateral increase in skin temperature.     

ANKH Polymorphisms and Clicking of the Temporomandibular Joint in Dental Residents

Aim

This study aimed to carry out a case-control research study to assess occurrence of clicking of the temporomandibular joint (TMJ) in order to establish the relationship between TMJ clicking and the genotype of “ANKH inorganic pyrophosphate transport regulator” (ANKH) polymorphisms.

Materials and Method

A sample of 41 first-year dental residents was selected. Each was examined using standard clinical procedures and genotyping techniques.

Results

The participation rate was 91.8 %. The prevalence of TMJ clicking was 51.2 % (95 % CI: 35.7–66.7 %). Occurrence of TMJ clicking was not related to age, gender and genotypes of ANKH-OR as well as ANKH-TR polymorphisms (p ≥ 0.165).

Conclusion

A similar distribution of ANKH genotypes in TMJ clicking and asymptomatic individuals has been demonstrated by this study. A high percentage of TMJ clicking has been confirmed. Future investigations are indicated.     

Symptoms and signs of temporomandibular disorders before, during and after orthodontic treatment

The relationship between orthodontic treatment and symptoms and signs of temporomandibular disorders (TMD) was studied prospectively and longitudinally in 65 adolescent girls with Class II malocclusion. The subjects received orthodontic fixed appliance treatment with the straight-wire technique combined with or without extractions and were examined for symptoms and signs of TMD before, during, after, and finally one year post-treatment. Both symptoms and signs of TMD showed considerable fluctuations over the three-year period within the individuals. The general tendency was a decreased prevalence of symptoms of TMD over the three years. The prevalence of pain on mandibular movement and tenderness to palpation of the masticatory muscles was significantly less common during and after orthodontic treatment than before. Clinically registered TMJ clicking increased slightly over the three year period. One orthodontic treatment effect when normalizing Class II malocclusions with fixed appliances was a decreased prevalence of functional occlusal interferences. We concluded that the orthodontic treatment either with or without tooth extractions did not increase the risk for TMD or worsen pre-treatment signs of TMD. Subjects with Class II malocclusion and pre-treatment signs of TMD of muscular origin seemed rather to benefit functionally from orthodontic treatment in a three-year perspective.     

Relationship between overbite/overjet and clicking or crepitus of the temporomandibular joint

AIMS: Since occlusal variables such as overbite and overjet have been thought to be associated with temporomandibular disorders (TMD), and joint sounds are some of the most prevalent signs of TMD, the aim of this study was to determine whether overbite and overjet are risk factors for temporomandibular joint (TMJ) sounds. METHODS: A population-based cross-sectional study of 3,033 subjects (age range, 10 to 75 years; 53% female) was conducted in Germany. Overbite/overjet, reproducible reciprocal clicking (RRC) during open-close jaw movements that did not occur in the protrusive jaw position, and joint crepitus were assessed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). RESULTS: When age and gender were controlled for, high or low values of overbite and overjet were not associated with a greater risk of RRC and crepitus as compared to a reference category of a normal overbite and overjet of 2 to 3 mm (multiple logistic regression; odds ratios 0.7 to 1.3; P > .05 for all). CONCLUSION: This study showed that higher or lower overbite or overjet jaw relationships, even extreme values, are not risk factors for TMJ sounds as assessed by clinical examination.     

ASSESSMENT OF TEMPOROMANDIBULAR DISORDER AND OCCLUSION IN TREATED CLASS III MALOCCLUSION PATIENTS

Objective:

The aims of this study were to compare the prevalence of temporomandibular disorders (TMD) in individuals submitted to either orthodontic or ortho-surgical Class III malocclusion treatment and to assess the influence of occlusal aspects on TMD severity.

Material and methods:

The sample consisted of 50 individuals divided into two groups, according to the type of treatment (orthodontic or orthodontic with orthognathic surgery). The presence of signs and symptoms of TMD was evaluated by an anamnestic questionnaire and a clinical examination, including TMJ and muscle palpation, active mandibular range of motion, joint noises and occlusal examination.

Results:

Based on the anamnestic questionnaire, 48% had no TMD, 42% had mild TMD and 10% had moderate TMD. The presence and severity of TMD did not show any relationship with the type of orthodontic treatment (p>0.05). The chi-square test showed a positive association (p<0.05) between TMD and non-working side occlusal interferences.

Conclusion:

Based on the methodology used and the results obtained, it may be concluded that Class III orthodontic treatment was not associated with the presence of TMD signs and symptoms and the non-working side contacts can be occlusal factors of risk. There was no significant difference in TMD prevalence between the studied groups (orthodontically treated patients and patients treated with orthodontics followed by orthognathic surgery).     

Changes in temporomandibular joint disc position and form following Herbst and fixed orthodontic treatment

Objective:To determine the changes in the position and form of the temporomandibular joint articular disc in adolescents with Class II division 1 malocclusion and mandibular retrognathism treated with the Herbst appliance (phase I) and fixed orthodontic appliance (phase II).Materials and Methods:Thirty-two consecutive adolescents went through phase I of treatment and 23 completed phase II. The temporomandibular joints were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during phase I (T2), at the end of phase I (T3), and at the end of phase II (T4).Results:Significant changes in disc position were not observed with the mouth closed between T1 × T3 (P  =  .317), T3 × T4 (P  =  .287), or T1 × T4 (P  =  .261). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 × T3 (P  =  .223) or T1 × T4 (P  =  .082). We did observe a significant difference between T3 × T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 × T2 (P < .001) and T2 × T3 (P < .001).Conclusions:At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4.     

Prevalence of temporomandibular disorder pain,jaw noises and oral behaviours in an adult Italian population sample

To evaluate the prevalence of temporomandibular disorder pain (TMD‐pain), temporomandibular joint (TMJ) noises, oral behaviours in an Italian adult population sample, their possible association with gender, oral behaviours, self‐reported facial trauma and orthodontic treatment. Subjects older than 18 years were recruited from general population in public spaces during their daily life. A specific questionnaire was developed to collect data on TMD‐pain, TMJ noises, oral behaviours, orthodontic treatment and facial trauma. A total of 4299 subjects were included in the study. The most common symptom in the sample was TMJ clicking (30.7%), followed by TMD‐pain (16.3%) and TMJ crepitus (10.3%). Oral behaviours were reported in 29% of the sample; 43.6% of the sample reported a previous or ongoing orthodontic treatment. TMD‐pain and TMJ clicking were significantly associated to gender, oral behaviours and a positive history of previous facial trauma. Crepitus was significantly associated to oral behaviours, facial trauma and higher age. Ongoing orthodontic treatment was significantly associated to TMD‐pain and TMJ sounds. In a general Italian adult population sample, TMD‐pain is associated to female gender and is less prevalent than TMJ clicking. TMDs are associated to trauma and oral behaviours.     

Treatment outcome of supervised exercise,home exercise and bite splint therapy,respectively, in patients with symptomatic disc displacement with reduction: A randomised clinical trial

The best treatment strategy for disturbing temporomandibular clicking sounds is not known. The aim was to evaluate the effect of exercise and bite splint therapy, respectively, in patients with symptomatic disc displacement with reduction. The study was a randomised clinical trial of subjects with temporomandibular joint (TMJ) clicking sounds with a reported severity/intensity of ≥4 on a numerical rating scale (0-10) and signs fulfilling the Research Diagnostic Criteria (RDC/TMD) for disc displacement with reduction. Thirty subjects each were randomised to bite splint, home exercise, or supervised exercise programme at the clinic. Two examiners (authors), blinded to the treatment modality, examined the same subject at baseline and at a 3-month follow-up. Non-parametric statistical methods were applied for analyses. A P-value <.05 was considered statistically significant. The dropout rate was highest in the home exercise group. About 50% of the participants reported improvement of their TMJ sounds with no significant difference between treatments. In the supervised exercise and the bite splint groups, approximately 2/3 of the patients reported 30% or more improvement of their TMJ sounds and half reported 50% improvement or more. The supervised exercise group also showed reductions in TMD pain, neck disability, mood disturbances and somatisation. Jaw exercise programmes and bite splint treatments had positive effects on TMJ clicking. The supervised exercise programme had an additional effect on the subject's well-being and thus may help to encourage patient's empowerment and coping strategies.     

Malocclusion and TMJ disorders in teenagers from private and public schools in Mexico City

Objective: To identify, among Mexican teenagers from public and private schools, the frequency, severity of malocclusion and orthodontic treatment needs, and their possible association with temporomandibular joint disorders. Material and Methods: Fifteen-year-old students were recruited from public and private schools. Clinical findings were registered as follows: oral hygiene status with the Oral Hygiene Index-Simplified, malocclusion using the Dental Aesthetic Index (DAI), and TMJ disorders following WHO criteria. Negative binomial and logistic regression models were constructed for data analysis. Results: A total of 249 fifteen-year old students were included in the study (118 female 47.4%). 68% had a DAI score ≤ 25 (minor or no occlusal anomalies), 18% scored 26-30 (mild anomalies), 7% scored 31-35 (evident anomalies), and 6% scored ≥ 36 (major malocclusion). The most frequent anomalies were dental crowding in 50%, maxillary dental irregularity in 44.6%, mandible irregularity in 41.2% and excessive maxillary overjet in 37.8%. Among the students, 26.1% had clicking/muscle or TMJ pain, of these 12.3% showed pain during palpation. OHI-S > 1 was found in 34% of the participants. The negative binomial model showed an association between DAI score and TMJ disorders (P=0.041). Also the logistic regression model showed an association between malocclusion (DAI>25) and TMJ disorders (OR=2.58, p=0.002). Malocclusion was associated also with poor oral hygiene (OR=1.65, p=0.007), and with attendance to public schools (OR=1.97, p=0.039). Conclusions: TMJ disorders and DAI scores were significantly associated. Screening/Diagnostic programs for ortho-dontic and TMJ-disorders are needed, to identify and offer treatment to teenagers with major malocclusion and TMJ/muscle pain. Key words:Dental Aesthetic Index, DAI, crowding, Temporo Mandibular Joint disorders (TMJ disorders), Temporo Mandibular Disorders (TMD), occlusal anomalies, OHI-S.     

Dentoskeletal effects produced by a Jasper Jumper with an anterior bite plane

Objective:The aim of this retrospective study was to evaluate the dentoskeletal effects produced by a modified Jasper Jumper with an anterior bite plane for the correction of Class II division 1 malocclusion.Materials and Methods:A sample of 32 growing patients (mean age  =  11.9 ± 1.4 years) with Class II division 1 malocclusion and increased overbite were treated with a modified Jasper Jumper (JJ) and anterior bite plane protocol and compared with a matched control group of 30 subjects with untreated Class II malocclusion (mean age 12.2 ± 0.8 years). Lateral cephalograms were taken before treatment (T1) and at the end of comprehensive treatment (T2). Mean treatment duration was 2.1 ± 0.4 years. The T1–T2 changes in the two groups were compared with Student’s t-tests for independent samples.Results:The JJ group was successfully treated to a Class I occlusal relationship with a significant reduction in overjet (–3.9 mm, P < .001) and overbite (–3.1 mm, P < .001). The JJ group exhibited a significant increase in mandibular length and a significant improvement in maxillomandibular sagittal skeletal relationships. The lower incisors were significantly proclined, while the lower first molars demonstrated significant movement in a mesial direction.Conclusions:Use of a modified JJ appliance and anterior bite plane is an effective protocol for the treatment of Class II malocclusion with increased overbite and greater skeletal (75%) than dentoalveolar (25%) effects mainly at the mandibular level.     

Temporomandibular disorders in the active phase of orthodontic treatment

summary Subjective symptoms and clinical signs of temporomandibular disorders (TMD) as well as presence of headache, bruxism and occlusal interferences were examined in 50 patients (mean age 12.9 years) before, during and immediately after orthodontic treatment. The prevalences of signs and symptoms of TMD were high before the treatment in comparison with subjects in an epidemiological study. Except for TMJ sounds, signs and symptoms of TMD as well as presence of headache decreased during the treatment. The major factor for decrease of the dysfunction index during the treatment compared with before the treatment, was tenderness to palpation of the masticatory muscles. Although there was a high prevalence of occlusal interferences during treatment, they seemed to have little importance for development of TMD. One explanation may be that the orthodontically moved teeth are sensitive to contact resulting in a decrease of oral parafunctions. Such a decrease was also reported by the patients.     

Are occlusal features associated with different temporomandibular disorder diagnoses in bruxers?

Aims:

The present study was designed to test the hypothesis that dental occlusion may have a role in mediating the effects of bruxism in temporomandibular disorders (TMD) patients. It aimed to answer the clinical research question: in a population of TMD patients with clinically diagnosed clenching-type bruxism, are the different TMD diagnoses associated with different occlusal features?

Materials and methods:

A total of 294 TMD patients (73% females, mean age 38·3±9·2 years) who were positive for a clinical diagnosis of clenching-type bruxism underwent an assessment in accordance with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I, as well as a recording of nine occlusal features. Statistical analyses were performed to test the null hypotheses that: (1) no differences existed between the patients with or without the various occlusal features as for the prevalence of the various single and combined RDC/TMD group diagnoses (single variable analysis), and (2) having any specific occlusal feature makes no difference in distinguishing within the RDC/TMD diagnoses (multiple variable analysis).

Results:

The distribution of the different combination of RDC/TMD axis I diagnoses was significantly different in patients with laterotrusive interferences with respect to those without such interferences (chi-square?=?15·209; P?=?0·033) as well as in patients with a slide from retruded contact position (RCP) to maximum intercuspation (MI) >2 mm with respect to those without such slide (chi-square?=?4·029; P?=?0·012) and in those with or without molar class asymmetry (chi-square?=?17·438; P?=?0·015). Multinomial regression analysis showed that the model including the various occlusal features account for 20·4% of the variance for RDC/TMD diagnoses (Nagelkerke R²?=?0·204) and allowed the rejection of the null hypothesis that having such specific occlusal features makes no difference in distinguishing within the RDC/TMD diagnoses.

Conclusions:

Within the limitations of this study, it can be suggested that in a population of patients with TMD and clinically-diagnosed clenching-type bruxism, the patterns of TMD diagnoses may be influenced, at least in part, by the presence of some features of dental occlusion, namely, slide RCP-MI, laterotrusive interferences, and molar asymmetry.     

Impact of malocclusion and dentofacial anomalies on the prevalence and severity of dental caries among adolescents

Objectives:To investigate the association between malocclusion/dentofacial anomalies and dental caries among adolescents.Materials and Methods:A cross-sectional study was conducted with 509 adolescents aged 11 to 14 years enrolled at public schools in the city of Osório in southern Brazil. Parents/caregivers answered a structured questionnaire on demographic and socioeconomic variables. A trained examiner recorded the presence of malocclusion (Dental Aesthetic Index [DAI]), traumatic dental injury, and dental caries. Data analysis involved the chi-square, Mann-Whitney, and Kruskal-Wallis tests. Poisson regression with robust variance was used for the multivariable analysis.Results:A total of 44.8% of the adolescents had dental caries (mean DFMT  =  1.33 ± 1.84). The DAI index ranged from 15 to 77 (mean  =  29.0 ± 7.9); 43.6% of the sample had severe malocclusion and 11.6% had traumatic dental injury. The prevalence and severity of dental caries were significantly greater among adolescents with severe malocclusion. The multivariate analysis demonstrated that adolescents with severe or handicapping malocclusion had a 31% greater probability of having dental caries (prevalence ratio: 1.31; 95% CI: 1.02–1.67), independently of demographic, socioeconomic, or clinical aspects. The orthodontic characteristics associated with the occurrence and severity of caries were maxillary irregularity ≥3 mm (P  =  .021) and abnormal molar relationship (P  =  .021).Conclusions:Handicapping malocclusion, maxillary irregularity, and abnormal molar relationship were associated with the occurrence and severity of dental caries. The findings suggest that the prevention and treatment of these conditions can contribute to a reduction in dental caries among adolescents.     

The role of occlusal curvatures and maxillary arch dimensions in patients with signs and symptoms of temporomandibular disorders

Objective:To identify differences in occlusal curvatures and maxillary arch dimensions between subjects with signs and symptoms of temporomandibular disorders TMDs and asymptomatic subjects.Materials and Methods:One hundred subjects 78 female and 22 male who consented to participate in this research were examined for signs and symptoms of TMDs according to the guidelines of the Research Diagnostic Criteria for Temporomandibular Disorders RDCTMD. In addition, occlusal measurements were performed for all subjects on plaster models. All statistical analyses were performed with SPSS version 19.Results:Significant associations were revealed between the depth of the curve of Spee COS and temporomandibular joint TMJ sounds. Furthermore, maxillary arch width was negatively correlated to the steepness of the curve of Wilson. No differences were found between subjects with and without a history of orthodontic treatment.Conclusions:Subjects with TMJ sounds tend to have a flatter COS compared to subjects without TMJ sounds.     

The short-term treatment effects of face mask therapy in Class III patients based on the anchorage device: Miniplates vs rapid maxillary expansion

Objective:To compare the short-term treatment effects of face mask therapy with miniplates (FM-MP) and face mask therapy with rapid maxillary expansion appliance (FM-RME) in growing Class III malocclusion patients with maxillary hypoplasia.Materials and Methods:Twenty patients were allocated into two groups according to the anchorage device: FM-MP group (n  =  10; mean age  =  11.2 ± 1.2 years; miniplates in the zygomatic buttress area) and FM-RME group (n  =  10; mean age  =  10.7 ± 1.3 years; bonded or banded RME). The face mask was applied for 12 to 14 hours/day in both groups with a force of 400 g/side directed 30° downward and forward from the occlusal plane. Lateral cephalograms were taken before (T1) and after FM-MP or FM-RME therapy (T2). Skeletodental and soft-tissue variables were measured. Paired and independent t-tests were performed for statistical analysis.Results:Both groups exhibited significant forward movement of point A and posterior repositioning and opening rotation of the mandible from T2 to T1. The FM-MP group showed significant protraction of orbitale (ΔSNO), and the FM-RME group showed a decrease in overbite and an increase in Björk sum. Comparing the amount of changes between the two groups, the FM-MP group displayed greater forward movement of the maxilla than the FM-RME group (ΔSNA, ΔA to N perp, all P < .05). However, the FM-RME group exhibited a greater opening rotation of the mandible (ΔSNB, Björk sum, all P < .01; ΔPog to N-perp, P < .05) and labioversion of the maxillary incisors (ΔU1-FH, P < .05).Conclusion:FM-MP therapy induces a greater advancement of the maxilla, less posterior repositioning and opening rotation of the mandible, and less proclination of the maxillary incisors than FM-RME therapy.     

Can temporomandibular dysfunction signs be predicted by early morphological or functional variables?

The aim of the present study was to establish whether the early signs of various orofacial dysfunctions, malocclusions, or occlusal interferences can predict the development of temporomandibular dysfunction (TMD) in young adults. Forty-eight subjects referred for speech therapy and 49 controls participated in all four stages of this longitudinal study. The subjects were examined at the ages of 7, 10, 15, and 19 years. The phoniatrician diagnosed errors in place of articulation and problems in the movement and co-ordination of the speech articulators. Occlusion, TMD signs (palpatory tenderness of the masticatory muscles, and of temporomandibular joints (TMJ), jaw deviation on opening, and clicking), mandibular movement capacity and occlusal interferences were registered by the orthodontist. Multiple logistic regression models were applied in order to evaluate whether single signs of TMD at the age of 19 years were related to previous/present malocclusions or interferences, to misarticulations of speech, problems in oral motor skills, or other signs of TMD. The effect of gender was also considered. The results showed that excessive overjet was the only variable which seemed to consistently increase the risk of TMD. In addition, girls seemed to be more prone to the development of TMD than boys. Although, during growth, there were both local and central factors associated occasionally with TMD development, the predictive value of those variables in the estimation of the individual risk of TMD was rather small.     

A study of the influence of occlusal factors and parafunctional habits on the prevalence of signs and symptoms of TMD

PURPOSE: The purpose of this study was to investigate the prevalence of the clinical signs and symptoms of temporomandibular disorders (TMD) and the relationship between occlusal factors, parafunctional habits, and TMD in a young adult nonpatient population. MATERIALS AND METHODS: A questionnaire including data from a history and clinical functional examination was used in the study. All 230 subjects were male recruits, from 19 to 28 years of age (mean 21.3 years). RESULTS: Thirty-eight percent of the subjects reported at least one symptom, while in 45% of the subjects at least one sign of TMD was recorded. Temporomandibular joint clicking (40%) and pain on palpation (34%) were the most commonly recorded signs. Multivariate logistic regression analysis showed several weak but statistically significant correlations between the occlusal factors, parafunctional habits, and TMD in this nonpatient population. TMD signs were thus weakly correlated with malocclusion traits (angle Classes II/1, II/2, III, and cross bite), interferences in retruded contact position, midline discrepancy > or = 2 mm, < or = 10 contacts during maximal biting pressure, nonworking-side interferences, horizontal overlap > or = 5 mm, and parafunctional habits (teeth clenching and teeth grinding). CONCLUSION: Some association between occlusal factors and TMD signs was found. However, this association cannot be considered unique or dominant in defining subjects with TMD in the population.