Defective direct composite restorations--replace or repair? A survey of teaching in Scandinavian dental schools

A questionnaire based survey was undertaken in Scandinavian dental schools to investigate aspects of the teaching of the repair of failing direct composite restorations, as a conservative alternative to total restoration replacement. The findings indicate that all undergraduate students in Scandinavian schools are taught and gain clinical experience in the repair of direct composite restorations. Although the findings reveal general agreement in relation to the teaching of reasons and operative procedures for the repair of direct composite restorations, variations were found in relation to the teaching of indications for, and the expected longevities of such repairs.

Repair versus replacement of defective direct composite restorations in teaching programmes in United Kingdom and Irish Dental Schools

The teaching of the repair of direct composite restorations has been surveyed in United Kingdom and Irish dental schools. Based on a 100% response rate, the findings indicate that the vast majority of undergraduate students in United Kingdom and Irish dental schools are taught and gain clinical experience in the repair of direct composite restorations. There is general conformity with respect to the teaching in relation to operative techniques and materials used.

Removal of amalgam, glass-ionomer cement and compomer restorations: changes in cavity dimensions and duration of the procedure

This study investigated changes in the dimensions of Class II cavities following the removal of amalgam, glass ionomer and compomer restorations. In 30 extracted caries-free human molars, preparation for 60 mesio-occlusal and occluso-distal cavities (two cavities per tooth) occurred. With a CEREC 3 laser triangulation sensor and software-based construction analysis, the dimensions of the cavities at seven defined sites were measured. The cavities were randomized into four groups. Group 1 was restored with Ketac-Fil glass-ionomer cement, Group 2 with amalgam and Group 3 with Compoglass F compomer. In Group 4, Compoglass F was used in combination with photochromic Tetric Flow Chroma as a cavity liner. The completed restorations were then removed using 2x magnification and the cavities were once again controlled using the laser system. The duration of the removal procedure was also recorded. Changes in cavity dimensions (depth, height and width) following removal of the restorations were significantly smaller in Groups 1 and 2. Groups 3 and 4 were characterized by a significant overextension of the cavities compared to Groups 1 and 2 in all three dimensions. Group 4, with Tetric Flow Chroma as a cavity liner, showed better results than Group 3, but this improvement was not statistically significant. The duration of the removal procedure was significantly shorter in Group 2 than in the other groups.

Hemisection for treatment of an advanced endodontic-periodontal lesion: a case report

AIM

To emphasize the importance of primary endodontic treatment when dealing with endo-perio lesions and to demonstrate the considerable healing potential of the endodontic aspect.

CASE REPORT

After several years of unsuccessful symptomatic periodontal treatment, an advanced endo-perio lesion on a right-mandibular first molar was successfully treated by root-canal treatment and hemisection after the re-evaluation of the lesion. This successful treatment appeared to have a positive effect on the patient's general well-being.

KEY LEARNING POINTS

The origin of a combined endo-perio lesion is indicated by its clinical and radiographic appearance. The periodontal situation is often misinterpreted. The prognosis for the endodontic element of treatment is excellent. Local pathologic processes in the oral cavity may affect a patient's general health.

Cytotoxicity of modern dentin adhesives--in vitro testing on gingival fibroblasts

The present investigation was designed to test cellular toxicity of modern dentin adhesives. With the use of the products Ariston Liner, Etch & Prime 3.0, Optibond Solo, Prime & Bond NT, Scotchbond 1, and Syntac Sprint, test specimens were prepared according to the manufacturers' instructions and transferred into a culture medium. Eluates were obtained and pipetted onto fibroblast cultures, incubated, and subsequently stained. The respective cell densities and the numbers of normal, altered, and dead cells were determined and compared with control cell cultures. Statistical analysis of the data showed that all materials caused cytotoxic effects. Scotchbond 1 displayed the highest number of dead cells. The difference was statistically significant compared to Etch" 3.0, Optibond Solo, Prime&Bond NT, and the control. The lowest cell density was found for Scotchbond 1 and Ariston Liner. The difference was also statistically significant in comparison with Etch" 3.0, Optibond Solo, Prime&Bond NT, and the control. To conclude, all tested dentin adhesives caused cytotoxic reactions. Taking the limitations of an in vitro experiment into consideration, Prime&Bond NT, Optibond Solo, and Etch" 3.0 appear to be the most recommendable products, and Scotchbond 1 and Ariston Liner the least.

Influence of rubber-dam on the reconstruction of proximal contacts with adhesive tooth-colored restorations

PURPOSE

To clinically measure the influence of rubber-dam on the proximal contact strength after its reconstruction with tooth-colored restorations.

MATERIALS AND METHODS

The frictional forces during the removal of a metal strip from the proximal contact area were taken as measure for the proximal contact strengths of 46 restorations (35 ceramic inlays, 11 direct composite restorations). The teeth were separated with a rubber-dam and wedged thoroughly during the complete reconstruction procedure according to the multiple wedging technique. The proximal contact strengths were measured immediately before and immediately after removing the rubber-dam.

RESULTS

The contact strengths were statistically significantly lower immediately after the removal of the rubber-dam (1.07+/-0.82N) compared to the situation with the rubber-dam (1.99+/-1.21N). The amount of the reduction after removing the rubber-dam was statistically significantly higher between the second premolar and the first molar (1.45+/-1.06N) compared to the contacts between the canines and the first premolar (0.32+/-0.44N) and the first and second premolar (0.59+/-0.77N). No influence of the restorative material, the use and localization of retainers, localization of the restoration, or number of teeth under the rubber-dam was detectable.

CONCLUSION

Rubber-dam is recommended for adhesive restorations as it is helpful for achieving good adhesion between the tooth and restorative materials. Nevertheless, the application of rubber-dam seems to be a factor which complicates the reconstruction of adequate proximal contacts.

Comparative study of composite resin placement: centripetal buildup versus incremental technique

An in vitro study was performed to evaluate the effect of two different proximal restoration techniques with different matrix systems on the marginal seal and microhardness of Class II composite restorations. Results indicated that the lowest, however, not significantly different, microleakage was achieved in totally bonded deep Class II restorations prepared with margins surrounded by enamel when using transparent matrices and reflective wedges in combination with the centripetal buildup technique. Highest surface hardness of composite resin was related to transparent matrices and reflecting wedges.

Preparation of severely curved simulated root canals using engine-driven rotary and conventional hand instruments

This in vitro study evaluated the efficacy and safety of six different nickel-titanium engine-driven instruments used with a torque-controlled engine device and nickel-titanium hand and stainless steel hand instruments in preparation of curved canals. A total of 80 curved (36 degrees) simulated root canals were prepared. Images before and after were superimposed, and instrumentation areas were observed. Time of instrumentation, instrument failure, change in working length and weight loss were also recorded. Results show that stainless steel hand instruments cause significantly less transportation towards the inner wall of the canal than do nickel-titanium hand instruments. No instrument fracture occurred with hand instruments, but 30-60% breakage of instruments was recorded during instrumentation with the engine-driven devices. The working length was maintained by all types of instruments. Newly developed nickel-titanium rotary files were not able to prevent straightening of the severely curved canals when a torque-controlled engine-driven device was used.

In vitro dentinal surface reaction of 9.5% buffered hydrofluoric acid in repair of ceramic restorations: a scanning electron microscopic investigation

STATEMENT OF PROBLEM

Fracture of porcelain is a relatively common clinical misfortune. Recent research has indicated that strong bonds can be formed between composite and dental porcelain. Porcelain surfaces are etched with hydrofluoric acid and treated with silane coupling agents before composite application. The question is how exposed dentin may react to etching with hydrofluoric acid.

PURPOSE

This investigation examined the effect of 9.5% buffered hydrofluoric acid, of 36% o-phosphoric acid alone and in combination on the surface structure of cut human dentin.

MATERIAL AND METHODS

Human molar teeth were sectioned in approximately 0.8-mm thick slices and treated with different acids or their combinations. Application periods were 10, 60, and 180 seconds. Specimens were processed for SEM and for energy-dispersive x-ray (EDX) microanalysis.

RESULTS

The smear layer on the surface of sectioned dentin was not completely removed by hydrofluoric acid alone and that a dense amorphous precipitate was formed on the peritubular zone. Starlike structures in dentinal tubules were visible. EDX analysis revealed different fluoride content on the treated surface, dependent on the etchant used.

CONCLUSION

Topical application of hydrofluoric acid appeared to provide a dentinal surface with an amorphous precipitate of fluoride. This layer may be important both for resistance of dental caries in dentin and for bonding reactions.

Tooth-colored restorations of posterior teeth in German dental education

Optimizing the quality of tooth-colored restorations is one of the main topics of current research. But there is only little information available about university education in this field. The aim of this study was to collect and evaluate data about the different aspects of dental education in Germany concerning tooth-colored restorations. Based on the response to a questionnaire from 90% of all German dental schools in the fall of 1997 a detailed survey is given of the utilization, indications, practical procedure, problems and limitations of both direct and indirect tooth-colored restorations done by students. The results indicate a wide-spread use of directly inserted composite for posterior teeth in the different education programs. Indeed, the preferred preparation of the cavity margin differs from school to school. Rebuilding an adequate proximal contact and a precise fit at the gingival margin are looked upon as the main problems of class II composite fillings. Ceramic inlays are mainly inserted by students in advanced clinical courses with the insertion procedure being claimed as the main problem of this technique. The findings of this study mostly show the same limitations and difficulties of tooth-colored restorations in education as found by research. Partly different teaching concepts are reflected in the differing scientific results.

Erbium:YAG laser application in caries therapy. Evaluation of patient perception and acceptance

OBJECTIVES

In previous studies it has been demonstrated that the Er:YAG laser can be used to prepare cavities efficiently and without thermal damage to the adjacent dental hard and soft tissues. To investigate the patients' response to Er:YAG laser preparation of teeth, a prospective clinical study was performed in five dental hospitals.

METHODS

To evaluate patients' perception and response to cavity preparation a direct comparison was made between conventional mechanical preparation and Er:YAG laser preparation of caries in dental hard tissues. Half of the preparations were completed by the laser alone with standardized parameters, with the other half being mechanically prepared. The sequential order of treatment was randomized, and clinical parameters such as depth and location of the cavities were carefully balanced. A three-score evaluation scheme of patient responses was used: comfortable, uncomfortable, very uncomfortable. In addition the patients were asked to decide which was the more uncomfortable form of treatment and the preferred treatment for future caries therapy.

RESULTS

The study included 103 patients with 206 preparations distributed amongst 194 teeth. All teeth gave vital responses (ice test) before and after both types of treatment. The laser treatment was found to be more comfortable than the mechanical treatment, with high statistical significance. During treatment, the need for local anaesthesia was 11% for mechanical preparation compared to 6% during laser application. It was found that 80% of the patients rated the conventional preparation as more uncomfortable than the laser treatment and 82% of the patients indicated that they would prefer the Er:YAG laser preparation for further caries treatment.

CONCLUSIONS

The application of the Er:YAG laser system is a more comfortable alternative or adjunctive method to conventional mechanical cavity preparation.