Effect of composition and curing type of composite on adaptation to dentin cavity wall.
Adaptation to dentin cavity wall of three marketed and eight experimental composites was investigated by measuring polymerization contraction in cylindrical dentin cavities and by SEM observation. The cavity adaptation of light cured composites was always inferior to that of the chemically cured composite and, in the experimental composites, the optimum filler content was obtained.These facts indicate that cavity adaptation is affected significantly by the flow of the composites from the free surface into the cavity during polymerization.
Marginal adaptation of Class V restorations using different restorative techniques.
This in vitro study compares the marginal adaptation of Class V restorations with margins located half in enamel and half in dentine, which were placed using different restorative techniques. Five operative procedures were evaluated both in saucer-shaped erosion lesions and in box-shaped cavities with bevels in enamel. The five procedures included a composite inlay technique using both the chemically and the light curing versions of a resin based composite cement, a bulk placement technique using a chemically curing composite resin, an incremental technique and an incremental technique combined with a built-up base, using a light curing composite resin. A combination of Gluma/Clearfil served as the dentinal adhesive. The micromorphology of the tooth/restoration interface was analysed before and after thermal cycling; the marginal seal was analysed after thermal cycling only. In the conventional cavities, the restorations showed less leakage, and micromorphologically a better, but statistically insignificant superior marginal adaptation. The inlay technique rendered the best marginal quality in both enamel and dentine before and after thermal cycling. Due to the unique curing characteristics of the chemically cured composite resin and cement resulting in a significantly reduced rigid contraction, the inlays cemented with the chemically curing cement and the restorations placed with the chemically curing composite resin were superior to their light cured counterparts. The built-up base yielding a reduction of the composite mass did not enhance marginal adaptation because of the partial replacement of the strong adhesion to dentine mediated by the Gluma/Clearfil combination by the weaker bond promoted by the etched glass ionomer cement.
GLUTARALDEHYDE IN ENDODONTIC THERAPY - PHILOSOPHY AND PRACTICE
Abstract The generally accepted philosophy that in endodontics disinfection of the root canal is a primary condition for lasting results should be supplemented by the statement that irreversible fixation of the remaining proteins is also an important prerequisite for success. Irreversible fixation without any adverse tissue reactions can be achieved by the use of a 2 per cent aqueous solution of glutaraldehyde. This medicament is to be preferred to formaldehyde, the other commonly used fixative, because it has three additional properties: 1. 1. Irreversible bonding with proteins. 2. 2. Limited diffusion into tooth structure. 3. 3. No periapical irritation. When the root canal is flushed with glutaraldehyde, mechanical preparation automatically results in obturation, both of the main root canal and of the dentinal tubules in the apical area, by plugs of fixed dentine chips. Five-year clinical results of root-canal treatment completed in one appointment only using glutaraldehye show a success rate of 96 per cent for chronic and 89 per cent for acute periapical conditions.