Quintessence International, 01/1996

Chief disadvantages of the reversed stainless steel crown method for corssbite correction are the difficulty in adapting a preformed crown to fit the tooth in crossbite and the metallic appearance of the steel crown form. An inclined plane with ideal mechanical advantage for correction of individual anterior tooth crossbite can often be custom sculpted of resin composite and bonded in position. Treatment is rapid and inexpensive and requires little cooperation from the patient. The report describes and documents two cases that used bonded resin-composite slopes for anterior tooth crossbite correction.

Stress and strain patterns around two rigid implant designs used as an abutment were compared and the displacement of natural teeth was investigated. The finite-element method was utilized to determine the stress and strain distributions. The results were evaluated in terms of the maximal tensile and compressive stress and strain in the bone around the abutment tooth and implants. The results indicated that the ITI 1 (hollow screw) implant led to high stress concentrations particularly in the apical region. The stress-transferring characteristics of ITI 2 (solid screw) implant were found to be more suitable than were those of ITI 1.

A controlled clinical trial was carried out to compare the clinical effect of combined antimicrobial-mechanical treatment modalities on moderate-to-deep periodontal pockets in patients with adult periodontitis. Twelve patients having at least three nonadjacent sites of periodontitis were included in the split-mouth study. Gingival Index, Plaque Record, bleeding on probing, probing depth, attachment level, and recession depth were recorded immediately before treatment. In the control site, supragingival and subgingival scaling was performed with an ultrasonic scaler. One experimental site received supplemental irrigation with 15 mL of a 100-mg/mL tetracycline solution, while the other received a tetracycline-loaded fiber after mechanical instrumentation. Fibers were left in place for 10 days. Reevaluation 30 to 60 days after treatment showed that all three treatment modalities were effective in improving clinical parameters. No adjunctive effect on the healing response was obtained by augmenting mechanical debridement with tetracycline.

Migration of a mandibular canine across the midline (transmigration) is a rare condition. Bilateral transmigration is extremely rare, there being only two published accounts. Of the five cases of transmigration described in this report, one involved bilateral transmirgration. Treatment options are discussed.

This in vitro study compared three methods of surface treating gold alloys to improve resin adhesion. The tensile bond strengths and modes of failure between specimen pairs cemented with a chemically adhesive resin were recorded. Heat-treated gold alloy specimens were significantly more resistant to bond failure under tensile loading than were either alumina-blasted or tin-plated gold specimens. There was no statistically significant difference in bond failure between aluminablasted and tin-plated gold specimens. The surface treatment altered the mode of failure from adhesive and/or for alumina-blasted and tin-plated gold specimens to cohesive (within the resin) for heat-treated gold specimens. Three case reports are presented to illustrate clinical applications of heat-treated gold alloys.

The usefulness of splinting of severely loosened teeth in advanced periodontitis has been discussed extensively, both positively and negatively. Retention of patients' own teeth through the aid of this simple and inexpensive resin composite splint provides a satisfactory solution for many affected patients. The fabrication and placement techniques for splints for the anterior and posterior regions are described, as are additional indications for such splints, which are fabricated from resin composite and glass fiber bundles. Such splinting can be provided even for severely loosened, periodontally diseased teeth without danger of intraoperative tooth loss. Long-term retention of such teeth can be ensured only through a risk-oriented postoperative program of oral hygiene and regular examination of the splint.

The effects of four bleaching agents (Opalescence, hiLite, 30% hydrogen peroxide, and 30% hydrogen peroxide mixed with sodium perborate) and 37% phosphoric acid on the external surface of human enamel were examined with the scanning electron microscope. The materials were applied to the enamel surfaces of 60 specimens obtained from 10 teeth. Each test agent was applied to one specimen from each tooth. One specimen of each tooth was left untreated. Comparison to the untreated control surfaces revealed that enamel exposed to the bleaching agents underwent slight morphologic surface alterations. The enamel surfaces treated with phosphoric acid, in contrast, showed severe morphologic alterations.

The effects of etching with maleic or phosphoric acid on the adhesion of resin composite to resin-modified glass-ionomer cement restorative materials were evaluated through a shear bond test. These effects were determined with both recently set and aged cement. For the three resin-modified materials tested, compared to no etching, the two etchants improved or did not affect the adhesion of resin composite, regardless of the age of the cement. For a chemically cured material, included in the study as a control, the same effects were observed, except that etching of the recently set cement with maleic acid was detrimental to adhesion.

This scanning electron microscopic study evaluated the adaptation of two visible light-cured bases, Calcimol LC and Ionomseal, to the dentinal surface after the use of various techniques to insert the resin composite material. Twenty-eight Class I cavities were prepared and restored in four groups: seven Calcimol LC and resin composite placed with a bulk or an incremental technique; and Ionoseal and resin composite placed with a bulk or an incremental technique. The specimens were sectioned longitudinally through the center of the restoration and an impression was made with a poly(vinyl siloxane) impression material. When the tooth surfaces and the impressions made from these surfaces were compared in the scanning electron microscope, extra gaps on tooth surfaces were observed that were not apparent in the impressions. These extra gaps probably resulted from desiccation of tissues; thus, the observation of replicas was useful to eliminate the inclusion of false gaps in the analysis. The results indicated that there was no substantial difference between Calcimol LC and Ionoseal base materials placed under resin composite inserted with an incremental technique.