Quintessence International, 09/1990

Class V abrasion and erosion lesions restored with composite resin seem to be more susceptible to microleakage, because the gingival margin is usually placed in cementum and / or dentin. The purpose of this study was to evaluate the microleakage, in vitro, of two new dentinal bonding systems along with a positive and negative control. This study was accomplished using extracted human teeth and a calcium-45 radioisotope technique. The teeth were examined for microleakage at periods of 1 week, 6 months, and 1 year. The results at all time intervals indicated that the cavities restored with the new bonding agents and their respective composite resins leaked more than did the negative control, glass-ionomer cement.

This in vitro study was designed to evaluate the ability of fluorescent tubes and dental lights to help operators distinguish tissues (fissures), differentiate between tissues (at site dentinoenamel junction or between carious and sound dentin), and distinguish form of a tooth preparation (Class II and Class V cavities). Operators with normal color vision ranked the lights in order of preference for each type of specimen. In general, for the fluorescent illuminants, operators preferred lights with high color temperature values and high color rendering index values. A small group of color-blind observers indicated a preference for an illuminant of law color temperature and law color rendering index value. For dental lights, operators preferred a higher color temperature for examining fissures, the dentinoenamel junction, and the cavity preparation. No particular illuminant was preferred for distinguishing between carious and sound dentin. Many observers had dfficulty in choosing a preferred dental luminaire.

Copper sulfate reducer is useful for lightening and improving the diagnostic quality of dark radiographs The solution consists of capper sulfate, sodium chloride, and sulfuric acid. The radiograph is immersed and bleached in the solution until it turns white, redeveloped in weak developer, and fixed. Reduction is superproportional; that is, the percentage of reduction is greater in darker areas than it is in lighter areas. The degree of reduction decreases with increases redevelopment time. The reduced radiograph may have a gray, brown, or black image. Resolution is increased on the reduced radiograph.

This article describes a multidisciplinary approach to the treatment of a severe skeletal anterior open bite, complicated by severe chronological enamel hypoplasia, in a 12-year-old southern Chinese girl. Correction of the open bile, of which the cause was unknown, involved the extraction of all first permanent molars and provisional repair of the wafer-thin enamel to permit bonding of fixed orthodontic brackets. Several phases of maxillary and mandibular fixed appliance therapy followed. As she open bite resolved, further restorative treatment was performed. The result was stable 3 years after the end of retention. The case demonstrates the benefits of well-planned, integrated, multidisciplinary treatment.

The melanotic neuroectodermal tumor of infancy is a rare benign neoplasm that appears as a rapidly enlarging mass, most commonly in the anterior part of the palate. The tumor is believed to be of neurocrestal origin. The case report of a 3-month-old infant with a rapidly growing melanotic neuroectodermal tumor of infancy is presented. The tumor was surgically excised, and no evidence of recurrence has been found.

In this clinical investigation, a biodegradable collagen material was used in membrane and paste form is assess its suitability for use in guided tissue regeneration after surgery. A variety of healing responses in only the soft tissues were noted, ranging from gross necrosis to enhanced healing. The problems and limitations of regeneration procedures are discussed to explain the reasons for the observed healing of the tissues.

Forty-eight silane-coated, resin-bonded fixed partial dentures were monitored for up to 36 months. All were Cast in a nickel-chromium alloy, veneered with porcelain, silane- coated, and seated with a dimethacrylate adhesive. Two preparational concepts were performed: the classic Maryland concept and a more complex preparation yielding high mechanical retention and resistance. After 24 months only one prosthesis failed, as she experimental process can be considered suitable for adhesive prosthetics. No clinically significant difference was found between the two preparational concepts. Long-term evaluation is required to determine if high mechanical retention and resistance reduce stresses on the adhesive, improving the success rate of resin-bonded prostheses.

A properly fabricated provisional restoration will, among other things, provide acceptable esthetics. Although many materials has been used for provisional restorations, when esthetics is of primary concern, the choice is limited to tooth-colored resin materials. Recently, a tooth-colored, light-activated urethane dimethacrylate resin has been developed. This material has been reported to be useful for many prosthetic applications, including the indirect fabrication of provisional restorations. This paper presents a technique for the direct fabrication of single-unit provisional restorations using this material. The physical properties of this resin and the advantages and disadvantages of the technique are also discussed.

Camposite resin restorations undergo dimensional changes that can eventually result in marginal defects. Unlike silver amalgam restorations, which usually should be completely removed before the tooth is restored again, bonded composite resin restorations can often be repaired. Thin report demonstrates a step-by-step technique for repairing a defective Class I composite resin restoration with a new application of resin after elimination, of the defect. The method has proved successful over the last 8 years.

Base metal preceramic solder joints have been described as unpredictable and inconsistent in tensile strength. Compared to base metal postsoldered joints, presoldering with a gas-oxygen torch produces weaker joints that have increased porosity and voids. This investigation compared the tensile strength of base metal solder joints presoldered with a gas-oxygen torch to that of joints presoldered in a porcelain oven under vacuum. The mean (± SD) solder joint tensile strength was 460.0 (± 99.4) M Pa for the oven-soldered and 520.2 (± 37.8) M Pa for the torch-soldered specimens. A strong, consistent, void-free preceramic solder joint was produced between a nickel-chromium base and gold solder by both torch- and oven-presoldering techniques; however, preceramic soldering with a torch tended to result in a stronger bond.