Association between malocclusion and signs of temporomandibular dysfunction in female adolescents

The aim of the present cross-sectional study was to investigate the association between the different morphologic occlusal characteristics and signs of temporomandibular disorders (TMD) in female adolescents (n = 410) in the permanent dentition. The registration included morphologic occlusion and TMD clinical signs: TMJ sound, TMJ pain, muscle tenderness, restricted opening and opening deviation. The results showed that one or more clinical signs were recorded in 25.6% of the subjects. TMD was associated significantly with posterior crossbite, anterior crossbite, functional shift and midline shift. No association was found between TMD and molar relationship, overjet, overbite and crowding. INTRODUCTION Specific etiologic factors for Temporomandibular disorders (TMD) have not been found, and today it is still believed that the etiology is multifactorial. Malocclusion has been considered one of the etiologic factors of temporomandibualr dysfunction. 3) Different studies investigating the association of occlusal problems and TMD have been published; some were cross sectional others longitudinal. While most of these studies reported association of certain morphologic malocclusions with TMD. Other studies showed no significant correlation between TMD and malocclusion. In the Western region of Saudi * Associate Professor Department of Preventive Dental Sciences Orthodontic Division, Faculty of Dentistry King Abdul Aziz University Jeddah, Saudi Arabia Egyptian Orthodontic Journal 22 Volume 30 December 2006 Arabia the correlation between occlusal characteristics and TMD was only reported in children in the primary dentition. The aim of the present study is to investigate the potential association between morphologic malocclusion and signs of TMD in a group of adolescent females in the western region of Saudi Arabia. Materials and Methods The sample consisted of female school children attending the seventh, eighth and ninth grade; their age range was 12 – 16 years. Private and public schools were selected using a stratified selection technique from different locations in the city of Jeddah in the western region of Saudi Arabia. A total of 520 students were examined but only 410 fit the inclusion criteria. The participants were considered to constitute a reasonably cross-section of healthy Saudi school children in the respective age group. All students attending on the day of examination were included. Inclusion criteria were: all in permanent dentition stage, no present or previous orthodontic treatment, the absence of any clefts or craniofacial anomalies. Clinical Examination The examination was carried out by two examiners from the department of Preventive Oral Sciences, an Orthodontist and a Pediatric Dentist. Inter and intra examiners calibration and standardization was done prior to the commencement of the study. The examinations on the students were carried out in the schools under proper lighting. The students were seated upright during the intra and extra oral examination of occlusion and signs of Temporomandibular Joint Disorders (TMD). For each student a four-page registration chart was designed to include all TMD and occlusion criteria. A consent form was also obtained from students and their parents for participating in the study. Examination of Occlusion With the teeth in centric occlusion, the anterior-posterior, transverse and vertical relationships were examined and recorded as follows: I. Sagittal relationship: 1. Molar relationship was recorded as Angle Class I (neutrocclusion) Class II (distocclusion) and Class III (mesiocclusion). 2. Overjet was recorded as the horizontal distance between the facial surface of the mesial corner of the most protruded upper central incisor and the facial Egyptian Orthodontic Journal 23 Volume 30 December 2006 surface of the corresponding lower incisor recorded in millimeters using a periodontal probe. It was recorded as: 0-2mm, 3-6mm, more than 6mm or negative overjet. 3. Anterior crossbite (one or more maxillary incisors occluded lingual to the mandibular incisor. II. Vertical relationships: 1. Overbite was recorded as the vertical distance between the incisal edge of the most protruded upper central incisor and the incisal edge of the corresponding lower incisor using a periodontal probe. Overbite measured as: 0mm (edge-edge);  50%,  50%. 2. Anterior openbite: > 0mm 3. Lateral openbite (lack of contact between at least two pairs of antagonists). III. Transversal relationships: 1. Posterior crossbite was recorded as unilateral or bilateral when one or more of the maxillary molars occluded lingual to the buccal cusps of the opposing mandibular teeth. 2. Scissor bite (unilateral or bilateral) was recorded when one or more maxillary molars occluded buccal to the surfaces of the corresponding mandibular teeth. 3. Midline displacement (shift) of > 2 mm was assessed by: examining visually the midline of the dentitions, while in centric occlusion. This was further confirmed by using a dental floss from the forehead of the child along the midline of the nose down to the chin, while the child parts the lips and the dentition were still in centric occlusion. IV. Crowding, maxillary and mandibular, was recorded only in the anterior region when the incisors showed signs of overlapping or rotation or when there was lack of space of >3 mm. Examination of TMD 1. TMJ sound: Digital palpation (19) of the TMJ was done using the middle and index fingers during opening and closure of the mouth. (20) 2. Muscular disorder: Digital palpation of the TMJ and associated muscles was performed to detect tenderness using the index, middle and third finger. The masseter, temporalis and the sternoclavicular muscles were palpated bilaterally for tenderness according to the method of Vanderas. The TMJ Egyptian Orthodontic Journal 24 Volume 30 December 2006 was also assessed for tenderness during mandibular movement according to the method of Dworkin. 3. Range of the mandibular motion: The amplitude of maximum vertical opening (MVO) was recorded using a Boley gauge. The gauge was placed on the mandibular incisor edge adjacent to the midline. The child was asked to open as wide as possible and the inter-incisal distance measurement was recorded. This process was repeated twice, and the average was obtained. The overbite value was added to the measurement to obtain the MVO. In cases of openbite the inter-incisal distance was subtracted to obtain the exact MVO. (22) The opening deviation was defined as the displacement of the mandible at least 2mm to the right or left of an imaginary vertical line when the mandible had reached half of its vertical opening. The child was asked to open the mouth slowly and this was repeated several times for confirmation. (20) A child was diagnosed as having TMD, if there is any single positive finding in the TMJ, the muscles or the opening criteria presented above. Statistical Analysis Statistical analysis was done using SPSS package. The chi-square method was used to determine the association between the different TMD signs and morphological malocclusion. The level of significance was set at P<0.05. Interand intraobserver reliability between the two examiners were 0.93, 0.94, respectively.