Comparative evaluation of matrix systems on proximal contact strip force and surface geometry in class II direct composite restorations: an in vitro study

Abstract Background Proximal contact strip force and surface geometry remain challenging in Class II composite restorations, with matrix system selection being a key factor. This study aimed to compare the proximal contact strip force and surface geometry of the myQuickmat Classico sectional matrix system and the myQuickmat all-round circumferential matrix system in Class II MOD composite resin restorations. Methods Twenty typodont molar teeth (Nissin Dental Products Inc., Kyoto, Japan) with standardised MOD cavities were selected and equally allocated into two groups. Group 1 consisted of the myQuickmat Classico sectional matrix system (Polydentia SA, Mezzovico-Vira, Switzerland), and Group 2 consisted of the myQuickmat all-round circumferential matrix system (Polydentia SA, Mezzovico-Vira, Switzerland). Composite restorations were done using Tetric N-Ceram composite resin (Ivoclar Vivadent, Liechtenstein). Proximal contact strip force and surface geometry were evaluated using a universal testing machine and confocal profilometer (NANOVEA ST 400, USA). Normality was confirmed by the Shapiro-Wilk test, and differences between groups were analyzed by Student’s t-test and the Mann-Whitney U test (Jamovi 2.6.44); P < 0.05. Results The sectional matrix produced greater proximal contact strip force at mesial (1.903 ± 0.333 N vs. 1.473 ± 0.413 N; P = 0.020) and distal (2.807 ± 0.557 N vs. 1.721 ± 0.405 N; P < 0.001) surfaces. Both systems showed surface concavity; the circumferential system had significantly greater concavity area, depth, and smaller radius of curvature compared with the sectional matrix system (P < 0.001). Conclusions The sectional matrix outperformed the circumferential system; however, concavity was observed on the proximal surface with both systems, reflecting limitations in the design of the matrix band.