Effects of Rapid Maxillary Expansion on the Temporomandibular Joint: A Bone Scintigraphy Study

The purpose of this study is to assess the effects of rapid maxillary expansion on metabolic activity in the temporomandibular joints of young adult patients using scintigraphy.

The images belonging to temporomandibular joints were obtained from the retrospective scintigraphic records taken from 17 adult females (16.1 and 18.8 years of age and the mean age was 17.3±0.86 years) who had non-functional bilateral posterior crossbite, deep palatal vault and dental crowding, and had been treated with rapid maxillary expansion. Bone scintigraphy images were collected at three-time intervals: at the beginning of treatment (T1), during the opening of the mid palatal suture (T2), and at the end of screw activation (T3). Alteration in bone activity in the temporomandibular joint regions were evaluated in sagittal and transaxial slices. To determine the differences between the intervals, repeated analysis of variance and Bonferroni multiple comparison tests were applied.

In the right and left temporomandibular joint regions, significantly increased metabolic activity was exhibited between T1-T2 (p<0.001). At the time of opening the maxillary mid-palatal suture, the metabolic activity increased approximately 60% compared to the initial status. At the end of the active expansion period (T3), the change in metabolic activity was approximately 20% reduced compared to T2.

Metabolic activity intensification occurs in the regions of interest in the temporomandibular joint during rapid maxillary expansion. After mid-palatal suture opening, activity noticeably decreased (T2-T3). This decrease in bone activity suggests that the temporomandibular joint complex adapts to rapid maxillary expansion forces.