Longitudinal Changes in Masticatory Muscle Morphology and Elastographic Characteristics Following Restorative Treatment of Unilateral Dental Caries in Children: A Prospective Clinical Study

BACKGROUND: Unilateral dental caries may alter masticatory function by promoting asymmetric chewing; however, whether these functional changes are accompanied by morphological or elastographic changes in the masticatory muscles of children remains unclear. OBJECTIVES: To evaluate longitudinal changes in the thickness of the masseter, temporalis and anterior digastric muscles and in the strain-elastographic characteristics of the masseter muscle before and after restorative treatment of unilateral dental caries in children. METHODS: In this prospective clinical study, 25 children aged 6-12 years with unilateral dental caries underwent ultrasonographic examinations at baseline and 3 and 6 months after restorative treatment. Caries status was assessed using the International Caries Detection and Assessment System II (ICDAS-II), Caries Assessment Spectrum and Treatment (CAST) and Decayed, Missing and Filled Teeth (DMFT/dmft) indices. Bilateral thicknesses of the masseter and temporalis muscles were measured at rest and during contraction, whereas anterior digastric thickness was assessed at rest. Masseter muscle elastographic characteristics were evaluated using strain elastography with semi-quantitative red, green and blue (RGB)-based pixel analysis. RESULTS: No significant longitudinal changes were observed in muscle thickness on either the carious or non-carious side (all p > 0.05). Likewise, no significant elastographic changes were detected on the carious side. On the non-carious side, significant longitudinal differences were observed in resting red (p = 0.035), contraction green (p = 0.002) and contraction blue (p = 0.011) RGB proportions. Pairwise analysis showed a significant change in contraction green proportion between baseline and 6 months (adjusted p = 0.009), with a moderate effect magnitude (r = 0.592). CONCLUSIONS: Restorative treatment of unilateral dental caries was not associated with detectable short-term changes in masticatory muscle thickness. However, selected strain-elastographic characteristics of the masseter muscle changed over time despite stable muscle thickness. These findings suggest that strain elastography may provide information complementary to conventional ultrasonographic thickness assessment; however, the clinical significance of these changes requires further validation.