Histological studies of an adhesive paint-on restorative for cervical erosions

Resin restorations: leakage, bacteria, pulp

Through the development of composite resin materials, the acid-etch technique and dentin adhesives, dentists can now complete perfect and permanent dental restorations--restorations with a color and shape approximating the natural tooth, with perfect marginal adaptation, and no harmful effects to the surrounding tissues, including the dental pulp. However, newer cross-sectional studies indicate that marginal defects are still the main cause of replacement of resin restorations, and that their clinical durability is shorter than that of other types. Moreover, there is no doubt that gap preventive treatments can intensify pulpal reactions to resin restorations if bacterial leakage occurs. The present thesis is based on nine previously published studies (I-IX). The aims of the studies were: to examine the possibilities of minimizing the occurrence of bacterial leakage around resin restorations through the use of various gap preventive procedures, to extend our understanding of their mode of action, and to investigate the pulpal reactions associated with restorations with and without bacterial leakage. The results of earlier research are reviewed, as well as the various methods for registration of gap occurrence around restorations. Studies I-IX are described briefly and followed by a discussion of the results, a summary and some concluding remarks.

Human pulp reactions to resin restorations performed with different acid-etch restorative procedures

Fifty-eight experimental resin restorations were performed in intact, human premolars, using different leakage-reducing restorative procedures. These were conventional acid-etching and acid-etching followed by cavity treatment with an intermediary layer of low-viscous resin or the dentin adhesive NPG-GMA/ethanol. The teeth were extracted after 4 months and examined for pulpal inflammation/necrosis (I), reduction of odontoblasts (OR), and formation of tertiary dentin (TD). By the general linear model procedure, 91%, 34%, and 56% of the variations in I, OR, and TD, respectively, could be explained by variations in the experimental conditions. The significant independent variables were jaw, stage of root formation, width of pulp, width of cavity, marginal leakage, bacteria in the cavity, bacteria in the exposed dentinal tubules, and the restorative procedure. With regard to the restorative procedure the analyses showed that application of low-viscous resin increased the pulpal reactions OR and I, whereas cavity treatment with NPG-GMA/ethanol had no adverse biologic effect.