Clinical comparison of CAD/CAM nanohybrid composite and hybrid ceramic overlays in children with molar-incisor hypomineralisation: a split-mouth prospective randomized clinical trial.

objectivesThis prospective, randomized, split-mouth clinical study aimed to compare the clinical performance and survival rates of CAD/CAM-fabricated nanohybrid composite overlays (NCOs) and hybrid ceramic overlays (HCOs) produced using a digital workflow in first permanent molars (FPMs) affected by molar-incisor hypomineralisation (MIH). Clinical performance was assessed using the modified USPHS criteria, while tooth hypersensitivity was evaluated as a secondary outcome using the Schiff cold air sensitivity scale. MATERIALS AND

methodsTwenty children (40 MIH-affected FPMs) aged 8-13 years with MIH-TNI scores of 2b, 2c, 4b, or 4c were included. Using a randomized split-mouth design, one molar received an NCO (Grandio blocs, VOCO, Cuxhaven, Germany) and the contralateral molar an HCO (ENAMIC, VITA Zahnfabrik, Essen, Germany). All restorations were fabricated through digital impressions, CAD/CAM design and milling, and adhesively cemented using a universal dual-cure resin cement. Clinical performance was evaluated by two blinded examiners according to the modified United States Public Health Service (USPHS) criteria at baseline and at the 6-month, 12-month, and preliminary 18-month follow-ups. Tooth hypersensitivity was assessed using the Schiff cold air sensitivity test. Statistical analyses were performed using Mann-Whitney U, Fisher's Exact, Fisher-Freeman-Halton, Wilcoxon signed-rank, and Stuart-Maxwell tests (IBM SPSS v31; p < 0.05).

resultsBaseline demographic characteristics and MIH-TNI distributions were comparable between the groups (p > 0.05). Most modified USPHS parameters demonstrated clinically acceptable outcomes in both groups throughout the follow-up. No significant differences were observed between groups at baseline or at the 6-month follow-up regarding surface/marginal staining and postoperative hypersensitivity/tooth vitality according to the modified USPHS criteria (p > 0.05). At the 12-month follow-up, one HCO restoration was rated as Score 2 (Explorer catches slightly, without a visible gap) for marginal adaptation, and no statistically significant difference was observed between the groups for postoperative hypersensitivity (p = 0.050). All restorations were available for evaluation at the 6-month and 12-month follow-ups. Both materials demonstrated favorable short-term clinical outcomes according to the modified USPHS criteria. Preliminary 18-month data were available for 7 patients, among whom one restoration fracture was observed in the HCO group. Tooth hypersensitivity scores significantly decreased in both groups by the 6-month follow-up (p ≤ 0.001), and all treated teeth reached a Schiff score of 0 at the 12-month follow-up (p < 0.001).

conclusionsCAD/CAM-fabricated NCOs and HCOs showed favorable short-term clinical performance in selected MIH-affected FPMs up to the 12-month follow-up. Preliminary 18-month findings should be interpreted with caution, and longer-term follow-up of the complete cohort is required to determine comparative durability. CLINICAL RELEVANCE: Both materials may represent clinically feasible restorative options for selected pediatric patients; however, longer-term clinical follow-up is required. CLINICAL TRIALS: Clinical trial registration number: NCT06987448.