Quintessence International, 10/2000

The Cerec 3 system simplifies and accelerates the fabrication of ceramic inlays, onlays, veneers, and quarter, half, and complete crowns for anterior and posterior teeth. Cerec 3 software simplifies occlusal and functional registration. Proper occlusion is established accurately and quickly; manual adjustment is reduced to a minimum. The separate grinding device, working true to morphologic detail and with fine surface quality, is connected to the optical unit by radio control. Equipped with a laser scanner, it can also be used for indirect application through a standard personal computer. The Cerec 3 system is network and multimedia ready and, in combination with an intraoral color videocamera or a digital radiography unit, can be used for patient education and for user training. The Cerec 3 system thus is a diagnostic, restorative, training, and documentation center for the dental practice.

Objective: The purpose of this study was to identify the pulpal findings encountered by practitioners when accessing complete-coverage crowns that require nonsurgical root canal treatment and the relevance of coronal leakage to the success of the RTC. Method and materials: The survey package consisted of a cover letter stating the instructions, rationale, and purpose for the questionnaire, a questionnaire with 8 short-answer questions, and a stamped, self-addressed envelope. A randomized sample of active dentists (300 general practitioners, 300 prosthodontists, and 300 endodontists) was selected. Collected data were analyzed with the chi-square test. Results: A 60% response rate was obtained. Statistically significant differences were found among the practitioner groups, depending on the question. General practitioners and endodontists obtain access through crowns and maintain these crowns as final restoration significantly more often than do prosthodontists. Practitioners responded that teeth with complete crowns require nonsurgical root canal treatment after 5 to 10 years. Conclusion: Respondents believe that leakage must be addressed when endodontic access cavities in artificial crowns are restored after nonsurgical root canal treatment. General practitioners perform nonsurgical root canal treatment more frequently than do prosthodontists. Practitioners indicated that when teeth with complete crowns require nonsurgical root canal treatment, treatment is most often performed 5 to 10 years after placement of the crown. Keywords: complete-coverage crown, endodontist, general practitioner, leakage, prosthodontist, root canal treatment, survey

Objective: A survey was undertaken to categorize the materials used for the restoration of endodontic access openings through complete-coverage crowns after completion of nonsurgical root canal treatment. Method and materials: The survey package consisted of a cover letter stating instructions, rationale, and purpose for the questionnaire, a questionnaire of 8 short-answer questions, and a stamped, self-addressed envelope. A randomized sample of active dentists (300 general practitioners, 300 prosthodontists, and 300 endodontists), was selected. Collected data were analyzed with the chi-square analysis. Results: Most general practitioners (93%), endodontists (61%), and prosthodontists (75%) reported that they frequently or always permanently restore teeth after nonsurgical root canal treatment. Empress was the all-ceramic system used most commonly by prosthodontists (42%) and general practitioners (38%). A statistically significant difference in restorative material preference was found (P 0.0001), depending on the type of crown used. Conclusion: Amalgam alone and in combination with bonding agents are materials of choice for restoration of access openings through all-metal complete crowns, while resin composite is the choice for all types of complete crowns involving porcelain. Endodontists preferred other materials. Keywords: amalgam, bonding agent, complete-coverage crown, glass-ionomer cement, nonsurgical root canal treatment, resin composite, survey

Wine is an essential component of the Mediterranean diet. Its consumption is increasing in many industrialized countries due to effective marketing. Wine may also have effects in the oral cavity mainly due to its acidity and alcohol content. This article briefly describes some effects of wine, both beneficial and detrimental, on oral and general health. In particular, the effect of wine on tooth enamel is demonstrated.

Objective: The purpose of this study was to evaluate the teaching program of Class I and Class II resin-based composite (RBC) restorations in Brazilian dental schools and to observe if any differences were found from similar surveys conducted in North American, European, and Japanese dental schools. Method and materials: A questionnaire containing 15 questions was distributed to 92 Brazilian dental schools, and 64 (70%) schools returned the questionnaire. The questions inquired the amount of time the curriculum dedicated to teaching of posterior RBC restorations, future expectation regarding the teaching time, limitation in extension of the occlusal width and the proximal box in Class II, contraindications for placing posterior RBC restorations, protocol for using bases and liners, brand of bonding agents and RBC used, instruments and techniques employed for finishing, cost relative to amalgam restorations, and biologic reactions related to the use of posterior RBC. The responses were calculated as percentages based on the number of schools that responded to the questionnaire. Where appropriate, the Chi-squared test and the Fisher exact test were used for statistical analysis. Results: Of the dental schools that responded, 88% dedicated 10% to 50% of the teaching time in operative dentistry to posterior RBC restorations. A significant correlation (P = 0.041) was found between the percentage of time dedicated to the teaching of posterior RBC restorations and the higher cost of posterior RBC compared to amalgam restorations. Resin-based composite restorations cost 30% to 70% more than amalgam restorations in the 40% of dental schools that charged a fee. Posterior composites for large restorations in molars were used by 14% of the dental schools. Base and liner were not placed by 10% of dental schools in deep Class I or Class II RBC restorations. One school did not recommend acid etching of the dentin. Conclusion: No major differences were found in the teaching philosophy of posterior RBC restorations by comparing the Brazilian data to the data from similar surveys done in North America, Japan, and Europe.

Objective: This short-term (72- to 96-hour) in vitro study on fibroblasts evaluated the biocompatibility of 3 single-phase dental alloys by determining cellular proliferation rates and the expression of a glycoprotein, fibronectin, which is involved in cellular adhesion processes. Method and materials: Flow 2002 fibroblasts were cultured together with 3 single-phase dental alloys of different composition. Proliferation rates were determined by 5-bromodeoxyuridine incorporation. Fibronectin expression was determined by indirect immunofluorescence. Results: At 72 hours, cells cultured with the alloy containing the lowest amount of noble elements (gold, platinum, and palladium) and the highest amount of silver exhibited significantly less proliferation than did controls. At 96 hours, only cultures with the alloy containing the greatest amount of noble elements behaved in a way similar to controls. Fibronectin organization in fibrils and in focal adhesions was correlated to higher cellular proliferation rates. Conclusion: Fibronectin organization could be a useful tool to determine the biocompatibility of dental alloys. Among the noble elements, palladium by itself exhibits very good biocompatibility. These indications could be useful for practitioners in the choice of the best alloy for specific clinical applications.

Objective: The purpose of this laboratory study was to determine the bond strength of a base metal alloy to a high-noble alloy and amalgam when a new chemical adhesion promoter was used in conjunction with a resin cement. Method and materials: Specimens of high-noble alloy and amalgam were prepared in epoxy-filled rings. Base metal cylinders were cast. The ends of the cylinders and the metal bonding substrates were wet ground and air abraded with aluminum oxide. The base metal cylinders were cemented with Panavia 21 resin cement after application of 1 of the following to the high-noble and amalgam metal surfaces: (1) Alloy Primer, (2) ED Primer, (3) Alloy Primer and ED Primer, or (4) tin plating. Bond values were determined after 24 hours' storage and after 3 months' storage and thermocycling. Results: At both 24 hours and 3 months, tin plating yielded the highest bond strengths to a high-noble alloy, but the value for the Alloy Primer groups was not significantly lower. There was no statistically significant difference between the 24-hour and 3-month values within the 4 treatment regimens. Conclusion: Treatment of amalgam or high-noble alloy with either tin plating or Alloy Primer before bonding with Panavia 21 resin cement yielded equivalent bond strengths to a base metal alloy. ED Primer was not an effective metal primer. There was no advantage to combining Alloy Primer and ED Primer.

For 44 years Dr Hugo A. Owens was a distinguished practitioner and community leader in Portsmouth and Chesapeake, Virginia, and also served for a time as president of the National Dental Association. Besides his proclivity for dentistry, he was driven by two other passions: politics and civil rights. In 1970 he was one of the first African Americans ever elected to the Chesapeake City Council. He was reelected for the next term and appointed vice mayor, a position he held for 8 years. His political successes were preceded by his activities as a civil rights leader, which began in 1950 and lasted through the 1960s. In a remarkable series of negotiations and litigations, Dr Owens was the prime mover in the desegregation of the city of Portsmouth. In all three careers, Dr Owens used dentistry as a home base for the expression of his activist philosophy of providing help for others when they were unable to help themselves.