Quintessence International, 07/1992

Recent publications have suggested that chewing sorbitol- or sucrose-containing gum after a snack or meal can reduce development of caries by neutralizing dental plaque acids at interproximal sites in the dentition. To confirm these findings four volunteers wore appliances containing a miniature pH electrode. After plaque accumulation, subjects ingested a blowl of sugar-coated cereal with milk and 20 minutes later chewed a sorbitol-containing gum, a sucrose-containing gum, or did not chew anything for 20 minutes. After exposure to the cereal, the plaque pH fell within 20 minutes from apprxomiately 6.4 to 4.8. Sorbitol gum caused the pH to rise to 5.5, while the sucrose gum caused the pH to rise to only 5.1. After cessation of chewing, the pH in all cases dropped to 4.5 or lower. No statistically significan diftference could be shown between plaque pH changes with the various protocols. Gum chewing after eating caused only a transient elevation in plaque pH.

This article describes a combined amalgam-composite resin technique for the restoration of endodontically treated molars suffering from severe, subgingival coronal damage. The use of silver amalgam in the subgingival areas provides an effective interface and a proper barrier for restoring and reinforcing the rest of the crown with a composite resin material.

Improvements in dental materials and methods of their use necessitate continuing modifications of clinical techniques. This paper details a step-by-step procedure for restoring a Class V carious lesion with polishable, visible light-polymerizing composite resin combined with one of the new-generation dentin-enamel bonding systems.

This article reviews the literature on the use of hydrogen peroxide in three professionally administered bleaching techniques from historical, technique, and safety viewpoints. Safety over time, absolute safety, and relative safety of nonvital bleaching, in-office vital bleaching, nightguard vital bleaching, and over-the-counter bleaching kits are compared. The advantages and disadvantages of different bleaching options, as well as indications for individual or combined use of the techniques, are discussed. In addition, specific indications for the use of the nightguard vital bleaching technique are presented.

A number of home bleaching products have recently been introduced. This in vitro study evaluated the effect of three representative bleaching products on the microhardness and surface texture of hybrid and microfilled composite resin. Scanning electron microscopic examination revealed cracking of the microfilled specimens treated with carbamide peroxide gels (proxigel and White & Brite). White & Brite also caused slight roughening of the hybrid composite resin. Microhardness tests indicated that the treated composite resins became somewhat softer. However, the only statistically significant softening was associated with White & Brite.

This study compared two techniques of amalgam condensation for effect on early microleakage. Class V preparations were restored with a high-copper amalgam using peneumatic condensation or conventional hand condensation. Significantly less microleakage was observed when pneumatic condensation was used. Further, pneumatic condensation proved equally effective in reducing early microleakage whether or not a dentinal sealant was used as an intermediary.

The prupose of this study was to investigate in vitro the adaptation and condensation of the proximal section of amalgam restorations placed in Class II preparations of conventional and conservative designs. The amalgam restorations were placed with traditional hand instruments with and without the aid of an automatic amalgam condenser. The restorations and sections of the restored teeth were examined and scored for adaptation and porosity. The restorations in the preparations of conservative design, especially those placed without the aid of the automatic condenser, exhibited more adaptation defects, porosity, and voids than did the restorations in the preparations of conventional design. It is necessary to identify and describe instruments and technqieus that will facilitate the placement of amalgam restorations in preparations with limited access.

Some clinicians now advocate dentinal etching to eliminate microleakage around composite resin margins. This study evaluated the Kanca technique and three commercial dentinal adhesives, including Clearfil Photo Bond, which uses phosphoric acid to etch dentin. The Kanca technique and Tenure were the most effective systems tested. However, none of the bonding systems completely eliminated microleakage. Total sealing of dentinal margins is not predict able with current adhesives and composite resins.

Periodontal examinations were carried out preorthodontically and again 2 to 28 months after orthodontic uprighting of 20 molars (40 furcation areas) in 16 patients. Preorthodontically, patients presented with generalized periodontitis. Postorthodontically, nine of 20 buccal furcations had become more severe, one had improved, and ten remained unchanged. Lingually, nine worsened, and 11 had no change. Furcation area pocket depths increased in 35.0% of furcations, but did not change in 57.5%. Furcation root form was not associated with the degree of change. Possible mesial root extrusion was found in 60.0% of the uprighted molars. The molars showing root extrusion had furcations that increased in severity. Heavy uprighting forces contributed to extrusion, and some effect ma y have been due to periodontal inflammation and bone loss. Mandibular molars can be uprighted in patients with moderate periodontitis, but light intrusive forces in an inflammation-free environment are recommended.

The apical sealing ability of a tricalcium phosphate sealer was compared with that of three other sealers. Seventy roots of human incisors were cleansed and shaped and randomly assigned to one of seven groups of ten roots each. The root canal systems were obturated with gutta-percha and one sealer using the lateral-vertical condensation technique. The canal was sealed with Roth's sealer, Sealapex, Kerr root canal sealer, or Sankin apatite root sealer (Type I, II, or III). One group was filled with gutta-percha without sealer to serve as a control. After the roots were immersed in silver nitrate, the degree of dye penetration was measured under a dissecting microscope. Results indicated that Sealapex had the best sealing ability, followed by Sankin apatite root sealer, Type II. Roth's cement showed the most dye penetration. Canals that were obturated without sealer showed significantly greater apical leakage.