Clinical performance of glass hybrid and short fiber-reinforced composite restorations in MIH-affected molars: A 60-month split-mouth randomized controlled trial.

OBJECTIVES: This study aimed to compare the 60-month clinical performance of glass hybrid (GH) and short fiber-reinforced composite (SFRC)-supported microhybrid composite restorations placed in MIH-affected first permanent molars following selective caries removal (SCR). MATERIALS AND METHODS: Thirty-one children (18 girls, 13 boys; 6-12 years) with MIH and at least two fully erupted first permanent molars exhibiting moderate-to-severe lesions (MIH-TNI scores 2 and 4) were enrolled. Following SCR, 62 molars were restored using a randomized split-mouth design. In each participant, one molar received a GH restoration (Equia Forte® HT), whereas the other selected molar was restored with an SFRC material (EverX Flow™) covered with a microhybrid composite resin (G-Aenial® Posterior). Clinical evaluations were performed at baseline and 6, 12, 24, 36, and 60 months using modified United States Public Health Service (USPHS) criteria. RESULTS: Clinical performance deteriorated significantly over time for both materials (p < 0.001). GEE analysis showed no significant independent effect of material type on any modified USPHS criterion (p > 0.05), while time significantly affected retention, marginal adaptation, postoperative sensitivity, and secondary caries (p < 0.001). Kaplan-Meier analysis demonstrated significantly higher survival rates for SFRC-supported microhybrid composite than for GH restorations at 60-month (75.5% vs. 59.2%; p = 0.002). CONCLUSIONS: Both GH and SFRC-supported microhybrid composite restorations provided clinically acceptable long-term outcomes in MIH-affected molars after SCR. Although clinical performance per modified USPHS criteria was comparable, SFRC-supported microhybrid composite restorations demonstrated superior long-term survival. CLINICAL RELEVANCE: When long-term durability is a primary consideration, SFRC-supported microhybrid composite restorations may be preferred for the restorative management of MIH-affected molars. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT07733804.