Comparison of Four Universal Adhesive Protocols for the Internal Adaptation of Composite Restorations in Primary Teeth: An In Vitro Micro-CT Study.

Achieving an acceptable adhesive interface is necessary for the long-term success of composite restorations in primary teeth. This study compared the three-dimensional internal adaptation of composite restorations in primary second molars among four prespecified universal adhesive product-application protocol combinations using micro-computed tomography (micro-CT). Seventy-six extracted primary second molars were randomly allocated to four experimental groups (n = 19): G2-BOND Universal/self-etch, G2-BOND Universal/selective enamel etching, G-Premio Bond/self-etch, and G-Premio Bond/selective enamel etching. Following restoration and thermocycling (5000 cycles), whole-cavity interfacial gap volume percentages were quantified using micro-CT. Data were analyzed using the Kruskal-Wallis test followed by Dunn-Bonferroni-adjusted pairwise comparisons. An overall difference was detected among the four experimental groups (p = 0.016). Following adjustment for multiple comparisons, the G2-BOND Universal self-etch group showed a lower whole-cavity interfacial gap volume percentage than the corresponding selective enamel-etching group (adjusted p = 0.013). No other adjusted pairwise comparison reached statistical significance. Within the limitations of this laboratory study, these findings are restricted to the tested product-application protocol combinations and do not demonstrate an interaction between adhesive system and application mode.