Quintessence International, 05/1994

Banding of molars is still the attachment mode of choice to the majority of clinical orthodontists. One of the acknowledged hazards of orthodontic treatment continues to be the presence of clinicaly detectable areas of enamel demineralization following the removal of orthodontic appliances. Factors that contribute to this demineralization include inaccurate adaptation of the bands and breakdown of the seal as a consequence of the inadequate bonding strength of the cements and their solubility

Composite resins have been advocated as a reinforcing build-up material for badly damaged endodontically treated teeth with flared canals. However, the control of an autocuring composite resin is difficult because it polymerizes rapidly within the root canal. While the light-curing composite resins are more user friendly, their polymerization can be a problem deep in the root canal. Light-transmitting plastic posts allow the transmission of light into the root canal and enable intraradicular composite resin reconstitution and reinforcement of weakened roots. At the same time, the light-transmitting plastic post forms an optimal post canal in the rehabilitated root and can accurately fit a matching retentive final post. These light-transmitting posts are a useful addition to the dental armamentarium.

Recent interest in amalgam as a restorative material has been directed toward the development of the bonded amalgam restoration. The literature regarding the theoretical and clinical aspects of this technique is reviewed. Four cases of successful treatment of cracked-tooth syndrome with the bonded amalgam restoration are presented.

Most acid-etchant gels are thickened with silica, which can leave a particulate residue on dentinal surfaces. Some newer etchants are thickened with polymers, which reportedly leave no surface residue. This study used scanning electron microscopy to examine dentinal and enamel surfaces that had been etched with either silica- or polymer-thickened gels. The silica gels left particulate debris on dentinal surfaces, and this debris was not removed by rinsing with water. There was little evidence of this contaminant on enamel surfaces. Enamel and dentinal surfaces treated with the polymer-thickened gels appeared to be clean and uncontaminated. Shear bond strengths of composite resin to enamel and dentin etched with the different types of gel etchants were also evaluated. Silica contamination did not adversely affect bonding. in fact, etching with silica-thickned gels resulted in slightly higher bond strengths to both substrates. However, the differences were not statistically significant.

While dentin-bonded crowns may hold esthetic advantages over metal-ceramic restorations, and minimal tooth preparation may also be appropriate, resistance to fracture of the restored unit is an important consideration. Dentin-bonded corwns were placed on standardized preparations in two groups of 10 maxillary premolar teeth in vitro. The preparations differed only in degree of taper. The restored specimens were subjected to compressive loading at 1 mm/min from a steel bar placed along the midline fissure. Mean fracture loads of 0.77 kN (6-degree taper) and 0.71 kN (8-degree taper) were recorded for the groups of prepared teeth, and a mean fracture load of 0.97 kN was obtained for a group of unprepared controls. Statistical analysis indicated that there was no significant difference between the fracture load of the 6-degree taper group and that of the sound control teeth.

The provision of satisfactory complete dentures requires that dentist, technician, and patient adequately fulfill thei respective roles in the provision of, and adaptation to, these dentures. The clinician should combine clinical skills and appropriate patient management, in addition to an appreciation of postextraction resorptive changes in the alveolar ridges, if clinically acceptable dentures are to be prescribed. An increasing number of replacement dentures are being prescribed for older patients; thus, the need to utilize functional factors to determine tooth placement is reviewed.

A patient presented with a draining sinus tract on the lingual alveolus of the posterior mandibular ridge. The source of the sinus tract was not readily apparent. Radiographis created the impression that a lesion of unusual and possibly metastatic origin might be involved. Comprehensive diagnostic tests were ordered, but the source of the lesion remained obscure until a surgical exploration was performed.

A case of a glandular odontogenic cyst is reported. All clinical, radiographic, and histopathologic features are discussed and compared with the descriptions in the literature already published about this new lesion.

The release of fluoride from a composite resin has been shown to inhibit enamel demineralization. The purpose of this study was to examine the remineralization effects of a fluoride-releasing resin. Twenty extracted molars were painted with an acid-protective varnish, excluding a 2 x 6-mm window. Artificial carieslike lesions were created in the exposed enamel with an acidified gel. A Class II preparation was restored with a fluoride-releasing or a non-fluoride-releasing composite resin. The teeth were sectioned longitudinally and photographed with polarized light microscopy in water and Thoulet's imbibition media. The sections were then painted with an acid-protective varnish, so that only the natural external surface of the lesion was exposed, and placed in separate closed enivronments of a nonfluoridated artificial saliva. Sections were removed after 2 weeks and 3 months and photographed under polarized light as before. A sonic digitizer was used to measure the area of the body of the lesion. Results demonstrated a statistically significant area reduction in the body of the lesions exposed to the fluoridated composite resin at 2-week and 3-month intervals.

This paper presents shear bond strength data and scanning electron photo micrographs of six dentinal adhesives: All-Bond 2, etched and unetched; Syntac; Prisma Universal Bond 3; Scotchbond Multi-Purpose; Tenure Solution; and Adhesive By Choice. The methods used in tooth treatment and scanning electron microscopic observation were identical to those used in previous studies. This permitted comparisons among a total of 13 dentinal adhesives (seven from prevous studies), all treated under the same experimental conditions and all currently available to the practitioner. Scanning electron micrographs showed the types of failures that occurred when the composite resin was fractured from the dentin. Most of the fractures were adhesive, with the exception of Scotchbond Multi-Purpose, whic h had many cohesive failures in the dentin or the composite resin. There was no significant difference among any of the shear bond strength values with the exception of Scotchbond Multi-Purpose, which was significantly stronger than the other five adhesives studied.