Quintessence International, 08/1990

The effect of fluoride, released from, a fluoride-containing composite resin, on secondary caries was investigated by quantitative microradiography In all teeth investigated. less demineralization was found near the composite resin than was found at a distance of a few millimeters from the material after an acid attack. The presence of the fluoridereleasing composite resin reduced the lesion depth measured after an acid attack by about 35%. Therefore, in vivo, a reduction of recurrent caries may be expected around fluoride-containing composite resins.

To compare the proximal adaptation and the marginal seal of different types of posterior composite resin restorations, 48 human molars were obturated in vitro with two direct techniques (three-sited light-curing technique and a multilaver technique) and one indirect technique. As a control, some specimens were obturated with amalgam. Half of the specimens were subjected to thermocycling. The micromorphologic adaptaion was evaluated with the scanning electron microscope and microleakage was evaluated with a dye infiltration test. Depending on the techniques used and on the level of the proximal gingival limit, only one half to two thirds of the investigated margins were rated excellent. The infiltration test revealed less leakage in enamel than in cementum. However, the results did not show statistical dlfferences in adaptation or in seal among the three composite resin techniques tested. Adaptation and seal in composite resin restorations were found to be inferior in all aspects to those of the amalgani restorations. The thermocycling did not induce marked changes in the results.

The purpose of this study was to test the difference between the strength of the marginal ridge of extracted teeth with a Class I composite resin restoration and the strength of the marginal ridge of teeth with a Class II amalgam restoration with retention grooves. A statistically significant difference in fracture strengths was found among groups. No statistically significant difference was found among restored preparations, beveling technique, and restorative material. Statistically significant differences in fracture strength were found between the whole tooth group and treatment groups; between the whole tooth group and Class II amalgam restoration group; and between the unrestored tooth preparation group and all other tooth groups.

In this study, the diffusion properties of the vapors of four canal antiseptics were examined. Tricresol, camphore-chlorophenol, Cresophene, and povidone-iodine in clinical doses were tested against Staphylococcus aureus and Streptococcus faccalis. Forty-five extracted human maxillary central incisor teeth were used, and their root canals were prepared. A small amount of antiseptic was placed on a cotton pellet in the pulp chamber of each tooth, and the chamber was sealed with Cavit. Vapors from each of the test medicanients produced zones of inhibition on Staphylococcus aureus and Streptococcus faecalis. The study showed that vapors of the test medicaments do pass through the apex of a tooth and thus have a potential effect at the periapical area. The largest zone of inhibition resulted from the vapor of tricresol.

A technique that utilizes acid-etched composite resin to maintain antimicrobial-containing acrylic resin strips in situ is described. The advantage of this technique is that placement of a periodontal pack is unnecessary, so control of supragingival plaque is not hindered at the site of the local antimicrobial delivery. The technique described may improve the effectiveness and the clinical acceptability of local antimicrobials in the treatment of periodontal disease

A repair technique is presented for elimination of black line crown margins and extension of margins onto cervical surfaces. A resin bonding agent that adheres simultaneously to metal, porcelain, and dentin is utilized to expedite completion of the repair. The bonding resin is opaqued with a light-curing, filled resin and then covered with a suitable composite resin. This technique updates a previously published technique by eliminating glass-ionomer cement liners and liner etching and improves both efficiency and esthetics of the repair.

One of the most gratifying composite resin bonding procedures for patients and dentists alike is closure of unwanted and unsightly interdental spaces. Various methods of performing such bonding have been described. The most modern composite resins are strong, tooth-colored materials that can exactly simulate the appearance of normal tooth structure and reliably stay in place for many years. A method of augmenting the mesiodistal coronal dimension of anterior teeth without mechanical preparation of the enamel described.

The resistance and retention of a fixed partial denture are influenced by the number and distribution of the abutment teeth that support it, the path of insertion, the shape of the arch to which it must conform, and the occlusal relationship it will have with the opposing teeth. If the prosthesis is to be designed properly, it is necessary to understand how each of these factors influences the stability of the prosthesis and its ability to resist dislodgment. If the conditions that contribute to the instability of the prosthesis are misunderstood, overlooked, or ignored, it is impossible to design a prosthesis that will be predictably successfull.

The cineradiographic technique was used to assess the retention of complete mandibular dentures during chewing. The study comprised ten complete-denture wearers with severe alveolar ridge resorption in the mandible. Two cineradiographic recordings were performed. with and without a denture adhesive spread onto the base of the mandibular denture. The analysis of the cineradiographic films disclosed a significant decrease in denture dislodgment, expressed as maximal value, when a denture adhesive was used. The mean dislodgment also decreased, but not significantly.

This report documents the case of a young patient who presented will, dental conjoining anomalies in both sides of the maxillary arch. One defect involved primary incisor twinning and the other a rare instance of primary incisor triplication three conjoined teeth.

Surface defects on stone casts threaten the accuracy of cast restorations. The aim of this study was to examine the relationship between critical convergence angle and voids in stone casts. Three addition silicone materials, one condensation silicone material, and one polyether impression material were used. The highest convergence angle at which voids presented at the tip of the specimens was recorded, and the number of voids found at margins and line angles of tile tooth preparations were counted. Results showed a positive and significant correlation between the critical convergence angle and the number of voids at margins and line angles of stone casts. Casts poured franz polyether impressions registered significantly lower critical convergence angle values and presented with fewer voids than did those fabricated from silicone materials.