Analysis of the stomatognathic system functions and mastication muscles in children affected by molar hypomineralization (MH): a cross-sectional study.

Purpose: To analyze the functions of the stomatognathic system in children with or without molar-incisor hypomineralization (MIH).

Methods: For this cross-sectional study, 72 children aged 6-12 years were recruited and divided in two groups: with MIH (G1) and without MIH (G2). T-SCAN was used to verify the distribution of occlusal contacts, gnathodynamometer to measure maximum molar bite force, and Iowa Oral Pressure Instrument (IOPI) to assess the strength of facial expression muscles. The t test and paired t test (p ≤ 0.05) were used for statistical comparisons.

Results: The molars affected by MIH exhibited lower distribution of occlusal forces (p < 0.001) and lower maximum molar bite force (p < 0.05) compared to the molars in the control group. However, there was no difference between the MIH-affected sides compared to the unaffected side, nor between the molars affected by MIH and their antagonists (p > 0.05). There were no differences in the forces of the facial expression muscles between the groups.

Conclusions: These findings suggest that MIH significantly impacts occlusal force distribution and bite force, but not facial expression musculature.