Introduction
The development of enamel and dentin acid conditioning techniques together with the improvement of adhesive restorative systems have resulted in restorations with a notable increase in durability and longevity because the adhesion of resin composite to dental tissues reduce or eliminate the need for removing healthy dental structures to gain adequate resistance and retention form.1,2,3 New adhesive systems are being continuously developed to improve the adhesion of resin composite to dental structure4, favoring its retention and reducing marginal microleakage.
Based on improvements of the original formulation of resin composite, countless professionals started to substitute these resinous materials for amalgam restorations.2,3,4,5,6 Although the initial results appeared promising, the intense clinical utilization of resins revealed serious deterioration and longevity problems.2 As a result, their use in posterior teeth has been questioned, especially in molar teeth.8
Concerns have focused on the tendency for excessive wear and polymerization shrinkage that are properties inherent in composite resins. Resin shrinkage generates stresses that may contribute to the disruption of the adhesive bond between the material and the dental structure if not dissipated. This can create gaps leading to marginal leakage resulting in postoperative sensitivity and penetration of microorganisms and/or their toxic products which in turn can cause pulpal lesions and recurrent caries.3,8 In fact, early resin composite restorations placed in posterior teeth demonstrated severe marginal leakage, occurrence of secondary caries, and substantial loss of material resulting in the loss of anatomic form and malocclusion.2
Although composite resins have become substantially better, many problems related to their original formulation have been only partially solved. Unfortunately, the manipulation characteristics of these materials remain relatively unaltered. As a result, restoring posterior teeth with resin composite using the same norms associated with amalgam results in a myriad of problems including postoperative sensitivity and an unacceptably high level of secondary caries.2
It is difficult for a clinician to select the most appropriate restorative system for posterior teeth due to the large number of brands of composite material available and with few differences among them. Two products available are Filtek P60 and Filtek Z250 (3M ESPE, St. Paul, MN, USA) which are light-cured, radiopaque composite resins designed for use as a direct posterior restoration with Filtek Z250 also indicated for anterior use. Filtek P60 has a total weight load of 84% and filled to 61% by volume and contains a greater number of smaller particles making it specifically designed for use as both a direct and indirect posterior tooth restorative material.
Many studies have been done to analyze marginal discoloration and integrity; evaluate the color, contour, and surface texture of restorations; assess the development of secondary caries; and to verify the effectiveness of adhesive restorative systems in the restoration of posterior teeth.2,4,9-11
Thus, the aim of this study was to evaluate the clinical performance of two resin composites (Filtek P60 and Filtek Z250) in Class I and II restorations using a modified United States Public Health Service (USPHS) system.
