Marginal and internal adaptation of Class II ormocer and hybrid resin composite restorations before and after load cycling

Abstract

To overcome the shortcomings of the conventional composite restorative materials, ormocer materials have been introduced over the past few years. The purpose of this study was to evaluate the marginal and internal adaptation of two ormocer restorative systems (Admira, Voco and Definite, Degussa) compared to a hybrid composite one (TPH Spectrum, Dentsply/ DeTrey), before and after load cycling in Class II restorations. Standardized Class II restorations with cervical margins on enamel were divided into three groups ( n=16). Teeth of each group were filled with one of the restoratives tested and its respective bonding agent. Each group was divided into two equal subgroups. The marginal and internal adaptation of the first subgroup was evaluated after 7-day water storage at room temperature and of the second after cyclic loading in a mastication simulator (1.2x10(6) cycles, 49 N, 1.6 Hz). The occlusal and cervical marginal evaluation was conducted by videomicroscope and ranked as "excellent" and "not excellent". One thin section (150 microm), in mesial-distal direction, of each restoration, was examined under metallographic microscope to determine the quality of internal adaptation. The occlusal and cervical adaptation of both ormocer restorative systems was similar and clearly worse compared with the hybrid composite restorative one before as well as after load cycling. Concerning internal adaptation, no gap-free ormocer restorations were detected, whereas all Spectrum restorations presented perfect adaptation. The bonding agents of the ormocers formed layers with unacceptable features (pores, fractures) whereas that of the hybrid composite achieved perfect bonding layer even after loading. The rheological characteristics of the bonding agents of the ormocer restorative systems are proposed to be responsible for their inferior marginal and internal quality in Class II restorations compared with the hybrid composite one.

Effect of different beverages on the color stability and degree of conversion of nano and microhybrid composites

“…In this study the use of the glass plate provided smoother surface for all materials tested. In agreement with our study it was found that Mylar strip formed the smoothest surface 23) . In addition to the finishing and polishing procedures may result in different surface textural changes and sub surface defects.…”

“…According to Kournetas, the degradation of the matrix results in hydrolysis of the bond with the silane coupling agent. Consequently it causes detachment of the filler, which accounts for most of the color change 23) . The increase in color change of resin composites stored in distilled water with time may occur due to presence of water which tends to soften the polymer by causing swelling of the network and reducing the frictional forces between polymer chain 20,21) .…”

A prospective randomised clinical trial of one bis-GMA-based and two ormocer-based composite restorative systems in class II cavities: Three-year results

“…The radiolucent line observed in the bite-wing radiographs could have been the consequence of bonding ''pooling'', described as typical for ormocer materials. 5 It is to be noted that in this study rather extensive restorations were placed. This fact was shown to have a negative effect on the quality of the restorations after exposure to the oral environment.…”

“…3,4 In laboratory studies not all of these claims have been substantiated. 5 Also, some clinical evidence cast doubts on the superiority of ormocer restoratives. 6 But none of the available ormocer restoratives have been evaluated in a comparative clinical study.…”

The Latest Developments Related to Composite Resins

“…Different to conventional composites, they are formed from inorganic-organic copolymers with silanized filling particles. In ormocers, which are formed of three basic components, while the organic polymer structure is responsible for resistance, the optical behaviours and the cross-link capability, the inorganic structure is responsible for thermal expansion and chemical stability and polysilicones do not affect the elasticity and interface properties (26).…”