Quintessence International, 01/2002

Basing the retention of mandibular complete dentures on two or four implants is now standard procedure in dental implantology. In addition to the almost traditional bar retainer, other retention elements are available for almost all implant systems. The method of primary splinting of four implants with a bar followed by immediate loading was described as early as 1979. The method described in the present report, derived from practical experience, is based on immediate loading of four interforaminal Ankylos implants without the use of a bar retainer. The denture is retained by prefabricated conical crowns that are placed into the existing denture base by direct intraoral polymerization immediately after surgery and supported by the corresponding conical primary implant abutments. This method facilitates secondary splinting by the inserted complete denture.

Objective: The aim of this study was to demonstrate the effect of low-powered magnification on the accuracy of caries detection and to compare it to the accuracy of unaided vision. Method and materials: Five dental models were prepared with extracted, unrestored, human permanent premolars, molars, and canines. Dental examinations were undertaken in simulated clinical conditions by seven dentists using both unaided and magnified vision. A true diagnosis was obtained by histologic sectioning, thereby allowing diagnostic accuracy to be calculated. Results: The sensitivity of diagnosis, representing the percentage of diseased sites found correctly, was significantly greater when magnification was used. There was no statistically significant difference in the specificities, or percentages of correctly identified healthy sites, between magnification and unaided vision. Conclusion: Magnification, although not perfect, improved significantly on the accuracy of diagnosis and can therefore be recommended for caries detection.

Objective: The purpose of this study was to compare the success rates of glass-ionomer cement restorations placed with the atraumatic restorative treatment approach and conventional cavity preparation methods. Method and materials: Two encapsulated, high-strength, esthetic conventional glass-ionomer cements were placed in 82 Class I and 53 Class II atraumatic restorative treatment and conventional cavity preparations, and an encapsulated amalgam alloy was placed in 32 Class I conventional preparations, in vital primary molars of 60 Chinese children aged 7 to 9 years. Results: The atraumatic restorative treatment preparations, made with hand instruments only, took approximately 50% longer to complete than did the preparations completed with conventional rotary instrumentation. After 1 year, there were no amalgam failures. For the glass-ionomer cement restorations, when the atraumatic restorative treatment method was used, significantly better survival rates were found for Class I (92.9%) than for Class II (64.7%) cavity preparations. There was also a strong trend for relatively better survival rates for the conventional cavity preparation method (86.7%) than for the atraumatic restorative treatment (64.7%) method for Class II cavity preparations. However, both the atraumatic restorative treatment and conventional methods appeared equally effective for Class I preparations. Conclusion: In a clinic setting, the use of atraumatic restorative treatment hand instruments for cavity preparation is more time consuming, and the method may also provide less mechanical retention and/or bulk of glass-ionomer cement for some Class II preparations in primary molars than does the use of conventional rotary instruments.

Objective: The aim of this study was to compare the coronal microleakage of conventional and bonded amalgam coronal-radicular (Nayyar) restorations on endodontically treated molar teeth, because coronal seal is a major factor in the long-term success of endodontic treatment. Method and materials: Forty extracted human molar teeth were root-filled and prepared for coronal-radicular amalgam restorations. Four groups of 10 teeth were restored with Tytin amalgam and Vitrebond, Superbond D Liner II, Panavia 21, or no adhesive agent. The teeth were placed in India ink for 1 week, and then demineralized and rendered transparent. The ink penetration was assessed with a coded scoring system. Results: The bonded amalgam groups produced significantly less leakage than did the nonbonded group. No statistically significant differences in leakage were detected among the bonded amalgam groups. Conclusion: To prevent the reinfection of the endodontically treated molar, it may be preferable to restore the tooth immediately after obturation by employing a bonded amalgam coronal-radicular technique.

Objective: The purpose of this study was to assess three modern root-end restorative materials with electrical and dye leakage tests. Method and materials: Thirty-three human canine teeth were prepared and filled with gutta-percha and sealer. Stainless steel rods were inserted into the root canals as anodes, and the teeth were varnished. The apical 3 mm of each tooth was resected, and 3-mm root-end preparations were made ultrasonically. Mineral trioxide aggregate, Super EBA, and IRM were used to restore 10 teeth each, and three teeth were varnished as controls. Following 24 hours' setting in blood, the specimens were placed in 1% potassium chloride electrolyte, and leakage was recorded electrically for 70 days. The teeth were then submerged in methylene blue dye for 72 hours, sectioned longitudinally, and scored for leakage by six examiners. Results: In both tests, the mineral trioxide aggregate restorations leaked significantly less than the IRM and Super EBA restorations. Super EBA showed significantly less leakage than did IRM restorations in the electrochemical test but not in the dye leakage experiment. The teeth sealed with mineral trioxide aggregate performed similarly to the varnished negative control teeth. Conclusion: The results of this study indicated that mineral trioxide aggregate provides a superior seal in root-end restorations.

A number of defense mechanisms may be activated in conjunction with restorative dental treatment. Tissue changes that lead to reduced dentinal permeability are important to minimize pulpal reactions. The healing potentials of the pulp-dentin complex are significant, and restorative dentistry is dependent on the available defense reactions. Clinicians should intentionally include considerations of these reactions in their treatment planning and during restorative treatment.