Milan Drobac

A method of improving marginal adaptation by elimination of singular stress point in composite restorations during resin photo-polymerization

OBJECTIVES To reduce the effect of stresses due to volumetric shrinkage the authors propose an incremental technique for placing composite restorations. METHODS The goal of the method is to reduce the volume of the resin that is polymerized and eliminate a stress singular point in the resin that is positioned at the geometric center of the cavity. This is achieved by a two step type incremental technique. In the first step the resin is placed in the cylindrical cavity with a metal pin embedded in the middle of the composite restoration. After polymerization, the metal pin is removed and the cylindrical hole is filled with the second layer of composite. Finally, the second layer in the center of the composite restoration is polymerized. RESULTS This study confirmed that the proposed incremental type placement technique reduces marginal debonding. SIGNIFICANCE The main hypothesis is that the elimination of a stress singular point at the center of the restoration results in the reduction of stresses at tooth-composite interface and therefore improve the marginal adaptation (reduces length of the contraction gap at tooth-composite interface).

The micromorphological characterization of adhesive bond in dentin different locations

The aim of this study was to analyse the interfacial micromorphology of total‐etch adhesives and dentin structures different locations by using SEM. Standardized cylindrical cavities (3mm in diameter, 2mm deep) with all margins in dentin were prepared on occlusal and buccal surfaces of twenty extracted human third molars. A total‐etch dentin adhesive system and a light‐cure flowable composite (Filtek Ultimate Flowable, 3M ESPE, St. Paul, MN, USA) were used in this study. Micro‐morphological SEM analysis of the marginal seal of the original tooth specimens was performed using high magnification of up to 1000×. In this study, we found the difference in interfacial micromorphology in dentin different locations. Also, marginal gap was found in both observed dentin area. Better understanding of complexity and three‐ dimensional variations of the tooth structure is important for prevention of clinical challenges such as postoperative sensitivity, marginal discoloration and secondary caries, which could be prevented by achieving of predictable and long‐lasting adhesive bond.

[One-year clinical evaluation of compomer restorations in cervical lesions of different aetiology].

INTRODUCTION The aim of this one-year prospective clinical study was to evaluate the treatment results of compomer restorations (Dyract eXtral Dentsply/De Trey, Konstanz, Germany) with a single step self-etching dental adhesive (Xeno III Dentsply/De Trey, Konstanz, Germany) used for restoring class V lesions (non-carious and primary carious cervical lesions). MATERIAL AND METHODS A total number of 62 class V restorations (n = 62) were placed by one dentist in 30 patients on incisors, canines and premolars. The fillings were placed due to different indications: non-carious cervical defects (n = 32) and primary carious lesions (n = 30). The restorations were evaluated by a single-blind design, according to the Modified United States Public Health Service system 6 and 12 months following the placement. The following were evaluated: retention, marginal integrity, marginal discoloration, wear; postoperative sensitivity and secondary caries. The statistical analysis compared the ratings of each criteria between materials using the Pearson chi-square or Fishers exact test at a level of significance of 5% (p < 0.05). RESULTS Two restorations of the non-carious lesion group were lost after 6 months, and after 12 months one restoration was lost in the group of primary carious lesions. There were no statistically significant differences between restorations for all evaluated criteria in both groups. CONCLUSION The compomer restorations in combination with a single step self-etching dental adhesive showed acceptable clinical performance in Class V lesions after one year of clinical service.