Do the Pre-Existing Class III and Class V Composite Restorations Affect the Sealing Ability and Integrity of 3D-Printed Laminate Veneer Margins? An In Vitro Study

Background: The application of veneer restorations over previously composite-restored anterior teeth presents significant clinical challenges, particularly in achieving optimal marginal sealing. Aim: This in vitro study aimed to evaluate the marginal integrity and sealing ability of different 3D-printed resin veneer restorations on sound versus composite-restored anterior teeth. Materials and Methods: Eighty freshly extracted human anterior teeth (40 central incisors and 40 canines) were randomly assigned into two main groups: sound teeth and composite-restored teeth. All the teeth received 3D-printed resin veneer restoration utilizing two different types of 3D-printed resin (GC Temp Print, GC, Tokyo, Japan; and Varseosmile Triniq, BEGO GmbH & Co., Bremen, Germany). The specimens were then subjected to microleakage, marginal fitness, cement void, and cement loss testing. Results: There were no statistically significant differences among all examined groups. Microleakage scores were predominantly 0 across all groups, with median values of 0 at both cervical and proximal surfaces. Marginal fitness showed fit percentages ranging from 20% to 100%, while cement voids and cement loss were rare events (<10%). Statistical analysis confirmed no significant differences between groups (p > 0.05), with p-values ranging from 0.151 to 1.000. Conclusions: No, the presence of pre-existing composite restorations did not adversely affect 3D-printed veneer performance. The marginal integrity and sealing ability of two different 3D-printed resin veneers are not affected by the presence of previous composite restoration on cervical and proximal surfaces for both incisor and canine teeth. 3D-printed veneers applied to sound and restored teeth showed good marginal integrity and proper sealing ability.