Influence of matrix systems on proximal contact tightness of 2- and 3-surface posterior composite restorations in vivo.

OBJECTIVES To investigate the influence of cavity preparation (MO/DO/MOD) and type of matrix system on proximal contact tightness of direct posterior composite restorations. MATERIALS AND METHODS 85 patients in need of a two- or three surface Class II direct composite restoration were randomly divided into two treatment groups. Group 1 was treated with a sectional matrix system combined with a separation ring (Palodent); Group 2 was treated with a circumferential matrix system in combination with a retainer (Tofflemire). Proximal contact tightness was recorded before treatment and directly after finishing the restoration. RESULTS For the two-surface cavities use of the separation ring resulted in a statistically significantly tighter proximal contacts at both the mesial and distal site (MO: 2.51±0.81 N; DO: 2.82±1.14 N) compared to the use of the circumferential (MO: -1.08±1.04 N; DO: -0.22±0.87 N) (p=0.01). Regarding the three-surface (MOD) cavities no statistically significant differences were found between the mesial and distal site, nor was there an effect of the used matrix system. No statistically significant influence of cavity design (mesially/distally) was recorded for all cavities (MO, DO and MOD). CONCLUSIONS Use of the sectional matrix system in two-surface Class II cavities resulted in statistically significantly tighter proximal contacts than the use of the circumferential matrix system. For the three-surface no statistically significant differences in contact tightness were found between the different matrix systems. Location of the cavity (mesially or distally) did not show to have any statistically significant effect on the obtained proximal contact tightness.