Influence of volumetric shrinkage and curing light intensity on proximal contact tightness of class II resin composite restorations: in vitro study.

Item does not contain fulltextBACKGROUND : Proximal contact tightness of class II resin composite restorations is influenced by a myriad of factors. Previous studies investigated the role of matrix band type and thickness, consistency of resin composite, and technique of placement. However, the effect of volumetric shrinkage of resin and intensity of curing light has yet to be determined. Thus, the aim of this study was to identify the influence of these factors on the proximal contact tightness when restoring class II cavity preparations in vitro. METHODS : Sixty artificial molars were restored with either a low-shrinkage (Filtek Silorane, 3M ESPE) or a conventional (Z100, 3M ESPE) composite and polymerized with low-intensity (Smartlite IQ2, Dentsply) or high-intensity light curing units (Demi(TM), Kerr). Proximal contact tightness was measured using the Tooth Pressure Meter. Data were statistically analyzed using one-way analysis of variance and Tukey post hoc test. RESULTS : Use of low-shrinkage composite (Filtek Silorane) resulted in significantly tighter proximal contacts compared to the use of conventional composite (Z100) when cured with the same polymerization unit (p<0.001). Moreover, the low-intensity curing unit (IQ2) resulted in significantly tighter contacts than the high-intensity unit when material is constant (p<0.001). CONCLUSIONS : Low-shrinkage resin composite and low curing light intensity is associated with tighter proximal contact values

Creating tight proximal contacts for MOD resin composite restorations

Item does not contain fulltextOBJECTIVE : The purpose of this study was to compare proximal contact tightness (PCT) of MOD resin composite restorations placed with different matricing protocols. METHODS : Forty-five ivorine lower right first molars with standardized MOD cavities were equally divided into three groups according to the restoration protocol. Group 1: Sectional matrix (Standard matrix, Palodent, Dentsply) secured with a wedge (Premier Dental Products Co.) and separation ring (BiTine I, Palodent, Dentsply, York, PA, USA) was used to restore the mesial surface first and then removed and repeated for the distal surface. Group 2: Identical to group 1, but separation rings were placed at both the mesial and distal sides (BiTine I+II, Palodent) prior to restoration. Mesial surface was restored followed by distal. Group 3: Walser matrix (O-form, Dr. Walser Dental GmbH) was used. Following composite resin restoration, PCT was measured using the tooth pressure meter. Data were analyzed using analysis of variance and a Tukey post hoc test (p<0.05). RESULTS : PCT values for mesial contacts were 2.99 +/- 0.47N for group 1, 4.57 +/- 0.36N for group 2, and 3.03 +/- 0.79N for group 3. For the distal contacts, the values were 4.46 +/- 0.44N for group 1, 5.12 +/- 0.13N for group 2, and 0.76 +/- 0.77N for group 3. Significantly tighter contacts were obtained for mesial and distal contacts for group 2 compared to groups 1 and 3 (p<0.05). For groups 1 and 3, mesial contacts were not significantly different (p=0.993), while distal contacts for group 1 were significantly tighter (p<0.001). CONCLUSION : Within the limitations of this study, tighter contacts can be obtained when sectional matrices and separation rings are applied to both proximal surfaces prior to placement of the resin composite in MOD cavities