Quintessence International, 05/1992

Although preventive resin restorations have been reported since 1977, there is little uniformity concerning the indications for this procedure, nor is there a standard technique. This article proposes diagnostic criteria for pit and fissure occlusal caries and diagnosis-related considerations for treatment planning for preventive resin restorations. A step-by-step laminate technique, which includes, successively, a glass-ionomer cement liner, a posterior composite resin, and a sealant, is described. The success rates reported for several clinical studies of preventive resin restorations are presented, although the criteria for this restoration, treatment methodology, and the determinates of success vary from study to study.

Certain enamel coloration defects can best be eliminated by a combination of treatment methods. This report describes the treatment of two patients whose enamel discoloration was corercted with a combination of enaeml microabrasion and patient-administered dental bleaching with a carbamide peroxide gel solution.

Early diagnosis of patients exhibiting open bites that are complicated by skeletal Class II and vertical growth problems can facilitate subsequent treatment. Eight patients with Class II skeletal open bite were treated with the high-pull activator appliance and compared to reasonably matched controls to determine the effects of the appliance. The high-pull activator was found to reduce forward growth of the maxilla and increase mandibular alveolar height, transforming the Class II molar relationship into a Class I molar relationship. The overjet and open bite were decreased, and, in addition, the applinace reduced the amount of forward and downward movement of the maxillary molars, providing vertical control of the maxilla during Class II orthopedic correction. These results demonstrated that open bite complicated by a Class II vertical growth pattern can be treated during the mixed dentition with favorable results by a combination of a removable functional appliance and high-pull headgear.

The aim of the present study was to assess the ability in vitro of phosphoric and citric acids, applied on human root cementum, to neutralize noxious plaque and calculu and to allow the growth of human gingival fibroblasts. Fibroblasts grown on cementum treated with phosphoric acid appeared typically elongated and aligned parallel to the root surface. Fibroblasts grown on cementum treated with citric acid, in both normal and periodontally diseased teeth, lost their elongated shape, acquiring polygonal borders with irregular cytoplasmic extrusions, and the cell density was significantly lower. These findings suggest that phosphoric acid cleaning of both normal and diseased root surfaces may result in an oriented, high rate of fibroblastic growth with more effective periodontal cellular proliferation than that observed after citric acid treatment.

Inadequate isolation will greatly compromise routine endodontic therapy. Loss of coronal tooth structure to caries or trauma often makes adequate rubber dam isolation difficult to achieve. This article presents some techniques for placing a buildup prior to endodontic therapy. The few minutes spent placing a buildup prior to the initiation of root canal therapy are an excellent investment in time. The time spent will be erpaid by the ease of placement of the rubber dam, the quality of isolation achieved, the reduced chance of losing the provisional restoration, and the increased quality of the completed endodontic treatment.

Transposition of teeth is a rare phenomenon. A case of bilateral transposition of maxillary canines and first premolars in a 27-year-old man is described.

Color vision is a critical component of restorative and esthetic dentistry, but dentists, as a group, do not have their color vision tested at any time during their careers. A study was undertaken to ascertain the color-vision status of practicing dental personnel at the University of Tennessee, College of Dentistry. One hundred fif ty individuals, 75 men and 75 women, were screened. The results corroborated the existing medical data for the general population. It was found that 9.3% of the men and none of the women exhibited color-vision defect. Since most dentists are male, this study demonstrates an area of potential weakness for some practitioners. Once a color-vision problem is found, it is simple to remedy by employing a team approach to shade matching or mechanical means of matching shades (by the practitioner). No ethnic or racial distincitions were detected, although these have been reported in other studies.

The effect of ten dentinal bonding agents on composite resin restorations was tested in mixed Class V cavity preparations. The marginal quality of the restorations was quantified under a scanning electron microscope before and after thermocycling. In addition, the marginal seal was semiquantitatively evaluated with a dye penetration technique. Marginal adaptation in dentin was poor in seven test groups. Three products showed values of excellent margin in dentin exceeding 50% after thermocycling. Furthermore, some dentinal bonding agents had a deleterious effect on marginal adaptation to the etched enamel surfaces.

The purpose of this study was to determine the prevalence of nonrepaired fractured incisors in visually impaired Chinese children and young adults in Hong Kong. Eighty-eight children were examined, and it was found that there were significantly more fractures of anterior teeth in the totally blind than in the partially blind. The totally blind seem to be at greater risk of sustaining a fractured anterior tooth than were the sighted.

To determine the effect of pressure variations on the retention of prosthetic crowns, 36 identical, cast metal crowns were fixed to simulated, epocy resin crown preparations with zinc oxyphosphate cement. Eighteen specimens were placed in a hyperbaric chamber and subjected to 15 cycles of simulated immersion at 30 m and decompression, as usually carried out by scuba divers. The untreated specimens served as controls. When the force required to dislodge the crowns was measured, the treated crowns were dislodged at about one third the load that was required to dislodge the control group, indicating that a statistically significant decrease in cement strength follows pressure variations.