Three-year performance of a nano-filled resin-modified glass ionomer cement in class II primary molar restorations

To compare the clinical failure rate of two resin-modified glass ionomer cements (RMGICs) used for Class II primary molar restorations over a 3-year period.

Healthy, cooperative children aged 4-8 years with carious, asymptomatic primary molars requiring class II restorations received either nano-filled (Ketac Nano, 3 M ESPE) or regular (Vitremer, 3 M ESPE) RMGIC restorations. These were blindly assessed semiannually for 3 years using the modified USPHS criteria with all-cause failure as primary outcome and failure for each criterion as secondary outcome. Data was analysed with Fisher's exact tests and survival analysis with robust standard errors at 5%.

Outcome assessment included 159 teeth at 12 months, 141 teeth at 24 months, and 98 teeth at 36 months. No difference in all-cause failure was found between regular and nano-filled RMGIC at 12 (8.6% versus 14.1%), 24 (9.0% versus 14.9%) or 36 months (7.4% versus 20.5%) (P > 0.05). The nano-filled RMGIC retained better its anatomical form and the regular RMGIC likewise its marginal integrity (P < 0.05), but only in the acceptable range (Alpha-Bravo). Overall, survival analysis found no significant difference for all-cause failure [hazard ratio (HR) 0.58; 95% confidence interval (CI) 0.25-1.31; P = 0.19] or any secondary outcomes other than contact point integrity. Finally, subgroup analysis by jaw indicated that the regular RMGIC performed better than the nano-filled RMGIC for mandibular molars (HR 0.36; 95% CI 0.13-0.96; P = 0.04), but further data are needed.

Nano-filled RMGIC showed less occlusal wear but more mild marginal defects than regular RMGIC, but these findings were of limited clinical significance and both materials performed favourably for 3 years.