Abstract
The aim of this study was to evaluate the fracture strength of teeth with different cavosurface margin cavity preparations and restored with composite resin and different adhesive systems. Eighty premolars were randomly divided in 8 groups, as follow: G1- sound teeth; G2- MOD preparation (no restoration); G3- Adper Single Bond without bevel preparation (butt joint); G4- Adper Single Bond with bevel preparation; G5- Adper Single Bond with chamfer preparation; G6- Clearfil SE Bond without bevel (butt joint); G7- Clearfil SE Bond with bevel preparation; G8- Clearfil SE Bond with chamfer preparation. The adhesive systems were applied according to manufacturers' instructions. Composite resin (Filtek Z250) was incrementally placed in all cavities. After 24 h, the specimens were tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test (fracture strength) and Fisher's exact test (fracture pattern). The confidence level was set at 95% for all tests. Prepared and non-restored teeth showed the worst performance and G4 exhibited the highest fracture strength among all groups (p<0.05). In conclusion, all restorative treatments were able to recover the fracture strength of non-restored teeth to levels similar to those of sound teeth. Using a total-etch adhesive system with bevel preparation significantly improved the resistance to fracture.
Highlights
Despite significant improvements in adhesive systems and composite resins in the last decades, some limitations are still present with these materials, such as polymerization shrinkage and questionable longevity of the adhesive interface
When prepared teeth are restored with adhesive materials, there could have a partial or total recovering of the fracture strength, depending on the type of adhesive system and restorative technique employed [4,5]
The aim of this study was to evaluate the influence of marginal cavity preparation and adhesive systems over the fracture strength of teeth restored with direct composite resin
Summary
Despite significant improvements in adhesive systems and composite resins in the last decades, some limitations are still present with these materials, such as polymerization shrinkage and questionable longevity of the adhesive interface. These critical factors can affect the fracture strength of restored teeth, being a problem for composite restorations, especially those placed in posterior teeth [1,2]. Beveling of cavity margins provides stability to the adhesive interface and has been suggested to improve the restoration retention [9], avoid microleakage [8] and increase the fracture strength of restored teeth [10]
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