Gnathological features in growing subjects

Aim of this study was to evaluate the prevalence of temporomandibular disorders (TMD) in a sample of consecutive subjects.

TMDs were recorded in a sample of 580 subjects (279 M, 301 F; mean age: 13.4y). For each subject a case history was compiled to evaluate the social and demographic parameters. An extraoral exam was effected to point out the face proportions, and an intraoral exam was performed to analyze dental occlusion, mandibular deviation during opening, presence of cross-bites, overjet and overbite. A functional exam was carried out to evaluate mandibular movements and to find joint sounds and myofascial pain. The sample was divided into 6 groups according to the: gender, age (ages 6y-11y and 12y-16y), Angle Dental Class, cross-bite, midline deviation and chewing side. For this investigation latex gloves, a millimeter calipers (precision 0,01 mm) and a phonendoscope were used. The percentages of signs and symptoms were compared using the ?2-test with Yates correction to determine the differences among the groups for the rates of TMDs, reduced opening/lateral/protrusive movements, and myofascial pain.

The prevalence of TMDs in the total sample was 13,9%. Among 6y-11y subjects the percentage of TMD was 7,3% while it was 16,1% among 12y-16y subjects (?2=1.634;; p=0.201). Females showed a percentage of 16,6% of TMDs while males one of 10,8% (?2=0.556;; p=0.456). According to angle malocclusion, the prevalence was 14% in subjects with Class I malocclusion, 15% in sample with Class II and 9% in patients with Class III (?2=0.540;; p=0.763). According to presence or absence of crossbite, prevalence of TMD signs and symptoms was 13,8% among subjects without crossbite and 14,3% among subjects with crossbite, with no significant difference between the two subgroups (?2= 0,047619;; p=0.050). In relation of midline deviation, prevalence of TMDs was 15% in subjects without deviation, 15,8% in functional deviation subjects and 4,7% in anatomic deviation ones (?2=1.555;; p=0.05). Prevalence of TMDs was 12,6% in subjects with bilateral chewing and 28% in unilateral chewing.

TMDs seem to be not associated to age, to gender, Angle Class, cross-bite and chewing side.