Quintessence International, 03/2001

A case of amelogenesis imperfecta with hypoplasia, hypocalcification of the enamel, congenital absence of teeth 12 and 22, delayed eruption of tooth 23, edge-to-edge incisal relationship, open bite, and bilateral posterior cross bite at the level of the first and second premolars is presented. Lateral skull teleradiography indicated a Class III skeletal pattern of maxillary origin associated with a dolichofacial pattern with multiple indicators of facial hyperdivergence. The patient presented a major esthetic abnormality of the face and required orthodontic treatment prior to a prosthetic solution with full-coverage metal-ceramic crowns in both the maxilla and the mandible. The diagnosis of cases such as this one and the therapeutic implications from an orthodontic and prosthetic standpoint are reported.

Objective: The aim of this study was to develop and test self-limiting diamond burs to ease precise chamfer preparation and to fulfill the special requirements of computer-aided design/computer-aided manufacturing and all-ceramic restorations. Method and materials: Rounded cylinder (based on ISO 881) and torpedo (based on ISO 879) diamond burs with a polished guide pin, 0.5 mm in length and 0.15 mm in radius, at the front end were developed in cooperation with an industrial partner. The in vitro testing involved a total of 140 human teeth. Experimental variables were the quality of the finish line, the microhardness of the enamel, and the thermal alteration of the dentin. Conventional diamonds served as a control. Results: No mechanical or thermal damage related to the bur design was found in the hard tissues that had potentially been in contact with or in close proximity to the guide pin. Microhardness of the enamel at the finish line was significantly higher when prepared with burs with a guide pin compared to conventional burs. The results of using the guide pin might indicate the beneficial effect of reduced vibration. Conclusion: The guide pins of the self-limiting diamond burs reduce, rather than increase, the risk of hard tissue damage at the preparation margin. No adverse effects were found. Clinical use is justified.

Objective: The aim of this investigation was to evaluate the clinical performance of 4 types of tooth-colored inlays. Method and materials: Fifteen direct ceramic inlays (Cerec Cos 2.0), 15 direct resin composite inlays (Brilliant Direct Inlay), 14 indirect ceramic inlays (Vita Dur N), and 14 indirect resin composite inlays (Estilux) were made in 37 patients, according to the manufacturers' instructions. The inlays were evaluated 1 week (baseline) and 6, 12, 36, 48, and 60 months after cementation (modified CDA Quality Evaluation System). Results: Two Vita Dur N inlays fractured after 1 and 4 years in function, and one Cerec inlay fractured after 4.5 years. Two Brilliant DI inlays needed replacement because of secondary caries (after 1 and 5 years), and one inlay (Estilux) needed replacement due to persisting hypersensitivity. Three inlays (1 Estilux and 2 Brilliant DI) were repaired due to chipping or minor fractures. During the observation period, the surface texture of Brilliant DI and Vita Dur N inlays became significantly rougher. After 5 years, the Estilux inlays had significantly lower ratings for morphology compared to baseline ratings. In general, the occlusal marginal adaptation did not show further disintegration of the luting cement after 1 year. Conclusion: Eighty-eight percent of the inlays were in function after 5 years. No significant differences were revealed among the survival rates of the different types of inlays.

Objectives: The purpose of this study was to evaluate and compare the resistance to crack propagation, as measured by the fracture toughness, of some packable posterior resin composites with other posterior resin composite materials. Method and materials: Fracture toughness determinations were made for the 5 packable and the other posterior resin composites using 3-point flexure of beams with a standardized central single-edge notch. Ten beams of each material were tested on an Instron test machine. The maximum loads were determined, from which the fracture toughness values (KIC) were calculated. The data were analyzed statistically using ANOVA and t tests. Results: The resin composites tested demonstrated a range of KIC values. The materials were separated according to the mean KIC values into 5 groups that were statistically different. While 2 packable resin composites had KIC values that were among the highest, the other packables were substantially lower than nonpackables. The intermediate value group consisted of 3 of the conventional posterior resin composites. Conclusion: There was a very weak correlation between fracture toughness and reported volume concentration of particulate reinforcing elements. The posterior resin composites tested exhibited a spectrum of KIC values. The packable resin composites were distributed along this spectrum, with 2 products exhibiting high potential for resistance to crack propagation.

Objective: This study evaluated the biocompatibility of two dentin bonding agents (Clearfil Liner Bond 2 and Scotchbond Multi-Purpose) applied in human dental pulps and cell cultures. Method and materials: In vivo: Twenty human third molars that were scheduled for extraction were used. After cavity preparation, pulp exposure was achieved with a carbide bur. Hemorrhage control was obtained with saline solution. In 16 teeth, adhesive pulp capping was performed and the cavities were sealed with resin composite. In the control group (n = 4), pulps were capped with Ca(OH)2 and the cavities were sealed with IRM. Teeth were extracted 30 or 90 days following treatment and prepared for histological examination and bacterial detection. In vitro: materials were applied in Petri dishes, where NIH-3T3 cells were plated. The cells were counted 2, 4, and 6 days after plating to obtain the growth curves and to determine cell viability. All data were submitted to statistical analysis. Results: In vivo: Dentin bridge formation was seen in all teeth capped with Ca(OH)2, without an inflammatory response. Mild inflammatory responses and dentin bridge formation after 90 days were observed in 50% of specimens treated with Liner Bond 2. Pulps treated with Scotchbond Multi-Purpose presented mild to severe inflammatory response, and no mineralized tissue formation was detected. Bacteria were not disclosed in any specimen. In vitro: The cytotoxicity was similar between the two bonding agents, and both had statistically higher cytotoxic effects (P 0.002) than Ca(OH)2. Conclusion: Ca(OH)2 produced pulp healing in all teeth and exhibited lower cytotoxic effects than both adhesive systems; however, pulp healing was also observed under Liner Bond 2.

Victims of Alzheimer's disease show a gradual and steady deterioration in memory, orientation, emotional stability, language capacity, abstract thinking, motor skills, and, ultimately, self care. Cognitive and motor deficits are accompanied by a gradual inabiltiy to perform adequate oral hygiene. Alzheimer's disease also interferes with the patient's ability to communicate dental symptoms of pain or dysfunction, and progressive deterioration of cognition interferes with the patient's ability to tolerate most therapeutic interventions. When treating patient's with Alzheimer's disease, oral health care providers must develop timely, preventive, and therapeutic strategies compatible with the patient's physical and cognitive ability to undergo and respond to dental care. They should strive to achieve those goals with the same ethical, moral, and professional standards of care as may be appropriate in the management of any other patient.

Diplopia caused by local anesthesia at the superior posterior alveolar nerve for the removal of the maxillary third molar is a rare complication. The diplopia is due to facial palsy of the oculomotor muscles of the globe. This paper describes the case of a 22-year-old woman, in whom diplopia was observed after an overall uncomplicated removal of the semi-impacted third molar. Possible causes of the anesthetic effects are reported. The most accepted explanation is that the anesthetic diffuses on the abducent nerve in the cavernous sinus. The necessary actions that the dental surgeon must perform are reported.

A case of an unerupted mandibular left permanent first molar, a partially erupted permanent second molar, and a congenitally absent third molar in a 12-year-old girl is described. The permanent first molar, being dilacerated and impacted, required surgical exposure of the crowns of the first and second molars and distalization of the second molar, with the help of a space regainer, to bring the molars into occlusion.

Ease of use, as applied to dental materials and techiques, means different things to different people. Factors that may contribute to ease of use include a minimum number of application stages, easy application and shaping ability, quickness of use, lack of stick, and moisture sensitivity. Ease of use may also imply that a material or technique does not cause stress for the dentist and patient, is cost effective, is easy to learn, and should provide the operators with a sense of satisfaction with their work. Similarly, clinical effectiveness of the treatments prescribed for patients is not always capable of being accurately defined. Suggested factors that may contribute to clinical effectiveness include a lack of patient complaints with respect to longevity and/or cost, no secondary caries, and preservation of the remaining tooth structure during functional loading. Ease of use and clinical effectiveness are not necessarily related, but they must be combined for a technique to be successful. The achievement of this demands a partnership between clinicians, manufacturers, and patients.

Objective: The objective is to determine if aerobic and anaerobic sampling yields viable biologic contaminants in the aluminum oxide air abrasion powder as delivered by the manufacturer and to determine mean particle size for comparison with the published size from manufacturers and the range of sizes in the powders. Method and materials: Samples from 15 unopened aluminum oxide powder containers from 9 different manufacturers were plated on aerobic and anaerobic culture media. The cultures were incubated at 35°C and observed at 24-hour intervals. Samples of each of the 15 groups were subjected to scanning electron microscope (SEM) examination. Photomicrographs were obtained and a range and mean particle size determined. Results: Aerobic and anaerobic cultures demonstrated no growth in any of the samples. Mean particle size determined by SEM for 25- to 27.5-µm particles ranged from 27.3 µm to 32.0 µm with standard deviations from 1.06 µm to 7.70 µm. Mean particle size for 50 µm particles ranged from 51.6 µm to 59.7 µm with standard deviations of 5.48 µm to 14.80 µm. Conclusion: Aluminum oxide powders as delivered by manufacturers appeared to be free from viable microorganisms. The powder mean particle sizes approximate the labeled sizes closely enough such that they should perform properly in air abrasion tooth preparation.

Objective: Historically, wide variations in the shear bond strength of resin composite bonded to dentin have been reported. The purpose of this study was to compare 5 commercially available single-bottle dentin bonding systems while controlling several sources of variation in shear bond strengths. Method and materials: Extracted molars were stored for 2 weeks in 0.5% Chloramine T. The teeth were mounted, the occlusal enamel was removed to expose middle dentin, and the exposed dentin was etched and treated according to 1 of 6 protocols. Finally, a cylinder of resin-based composite was bonded to the dentin. After 24 hours, specimens were fractured under shear force, and the results were recorded in megapascals. Results: The type of product used was significantly associated with the mean shear bond strength observed. All products exhibited some degree of variation from specimen to specimen. One product, PQ1, exhibited less variation than the other 4 products. Conclusion: PQ1 was found to have a significantly higher mean shear bond strength than the other 4 products tested. There was no significant difference between specimens bonded to dry dentin and specimens bonded to wet dentin when using PQ1.