Do condensable composites help to achieve better proximal contacts?

Objectives: Obtaining acceptable contact areas with adjacent teeth is a significant challenge when placing direct resin composite in Class II preparations. It was the purpose of this laboratory study to evaluate the influence of the type of resin composite (‘packable’ vs conventional) and of the matrix system on the quality of the proximal contact area in Class II composite restorations. Methods: A standardized DO cavity was prepared in 170 frasaco teeth. Two operators each filled 85 teeth in the same frasaco model using four resin composites [Solitaire (S), Surefil (Su), P60, Z100], three matrix systems [Automatrix (A), Palodent (P), Lucifix matrix (L)] and one hand instrument specially designed to achieve better proximal contacts [Belvedere Composite Contact Former (B)]. The teeth were subdivided into 17 groups (Z100/1–A, Z100/1–P, Z100/1–L, S–A, S–P, S–L, Z100/1–A–B, Z100/1–L–B, Su–A, Su–P, Su–L, P60–A, P60–P, P60–L, Z100/2–A, Z100/2–P, Z100/2–L). Each operator made five fillings of each group. The quality of the proximal contacts was assessed by measuring the maximum mesio–distal (M–D) diameter of the restored teeth using a digital micrometer and the tightness of the proximal contact area using standardized metal blades. All data were analyzed using two-way ANOVA and Bonferroni/Dunnʹs test for multiple comparisons with a significance level of P<0.05. Results: Regarding the matrix system, a significant larger M-D diameter and a stronger proximal contact area was achieved with the Palodent matrix system. The use of the Belvedere Composite Contact Former together with Lucifix matrix and Automatrix contributed to significantly stronger proximal contact areas. Concerning the type of resin composite, no significant differences were noted for both evaluation criteria when Palodent was used. Using Automatrix or Lucifix matrix, the more condensable resin composite P60 scored slightly better than Surefil and Z100. There was no operator effect. Both operators underwent a learning process. The longer they worked with a specific material/technique, the better proximal contacts they achieved. Significance: The best proximal contact areas in Class II composite restorations were obtained using a sectional matrix system. The ‘packability’ of the resin composite did not help to achieve better proximal contacts.