Effect of Stress Generated by Occlusal Cyclic Force on Class I Bulk-Fill Composite Restoration Microleakage.

Vanthana Sattabanasuk,Apirat Ritthiti,Pisol Senawongse,Kavin Karunratanakul

doi:10.1055/s-0041-1735433

Vanthana Sattabanasuk, Apirat Ritthiti + Show 2 more

Open Access

https://doi.org/10.1055/s-0041-1735433

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Abstract

Objective This study aimed to evaluate the effects of different types and restorative techniques of Class I composite restorations with a single loading force on stress distribution and cyclic loading force on microleakage formation. Materials and Methods Class I cavities were prepared in premolars with 4 mm depth and divided into six groups of different restorations with: (1) Filtek Z250; (2) a 3-mm-thick layer of Filtek Bulk Fill Flowable Restoration and covered with Z250; (3) a 1.5-mm-thick layer of flowable composite and covered with Z250; (4) lining all cavity with flowable composite and restored with Z250; (5) Filtek Bulk Fill Posterior Restoration; and (6) lining all cavity with flowable composite and restored with bulk-fill composite. The specimens with and without cyclic occlusal loading were subjected to microleakage observation. In addition, six different models of Class I restorations corresponding to the microleakage study were generated. Finite element analysis (FEA) was used to identify the stress distribution under a single loading force. Statistical Analysis Data were statistically analyzed by two-way analysis of variance and multiple comparison. The significance level set at 0.05. Results Cavity lining or restoration with flowable composite underneath conventional composite reduced stress on composite resin based on FEA (groups 2 and 3). The cyclic stress on composite increased microleakage. Restoration with flowable composite underneath conventional composite reduced the microleakage in Class I restoration (groups 2, 3, and 4). Conclusion The most effective cavity lining with a flowable composite underneath conventional composite restoration was stress reduction under loading force resulting in microleakage reduction.

Highlights

Posterior composite restorations have become widely used in dentistry because of their high success rate and conservation-related properties
This study aimed to evaluate the effects of different types and restorative techniques of Class I composite restorations with a single loading force on stress distribution and cyclic loading force on microleakage formation
The stress produced by occlusal loading for all models gradually decreased from high to low as follows: dentin, enamel, hybrid layer, and adhesive

Summary

Introduction

Posterior composite restorations have become widely used in dentistry because of their high success rate and conservation-related properties. Restorative materials are subjected to such cyclic stress and undergo material fatigue This fatigue may cause defects that lead to a fracture in the materials at a stress level lower than that required for a single load application.[4,5,6,7] A recent study reported the effect of a single stress of 50 N loading on a Class I composite restoration from a two-dimensional model of finite element analysis. It produced the highest stress of 62.75 MPa at the enamel cavosurface. Different resin composites with different compositions showed different fatigue strengths for the different materials.[10]

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