Tooth-colored restorations of posterior teeth in German dental education.
ABSTRACT 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.
- [show abstract] [hide abstract]
ABSTRACT: The gingival margins of class II composite restorations are particularly vulnerable to marginal leakage and secondary caries. In identifying the factors contributing to caries development, the molecular structure and differences in the structure at the proximal and gingival margins have been largely overlooked. The purpose of this study was to compare the molecular structure at the adhesive/dentin interface of the proximal and gingival walls of class II composite restorations. Class II preparations were cut in 12 unerupted third molars with a water-cooled high-speed dental handpiece. The prepared teeth were randomly selected for treatment with Single Bond (SB) + Z100 (3M). Teeth were restored, per manufacturer's directions, under humidity and temperature characteristic of the oral cavity. Restored teeth were kept in sterile Delbecco's phosphate saline for 48 h. The samples were sectioned occluso-gingivally and micro-Raman spectra were acquired at approximately 1.5-microm spatial resolution across the composite/adhesive/dentin interfaces. Samples were wet throughout spectral acquisition. Raman spectral characteristics at the proximal and gingival margins were distinctly different; the depth of demineralized dentin was 6-7 microm at proximal margin, 12-13 microm at gingival margin. SB adhesive penetrated the depth of demineralized dentin in a gradient at the proximal margin. The "single bottle" adhesive used in this study, gradually penetrated the depth of the demineralized dentin at the proximal margin but failed to infiltrate the depth at the gingival margin, leaving a thick exposed collagen layer.Journal of Biomedical Materials Research Part A 01/2006; 75(3):580-7. · 2.83 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Manufacturers have attempted to address the limitations associated with dentin bonding by eliminating as many steps as possible in the bonding protocol. Theoretically, this approach increases the efficiency of the procedure and reduces technique sensitivity. These trends are reflected in the introduction of all-in one, single-step adhesive systems; the increased concentration of acidic resin monomers in these systems allows for simultaneous etching and priming of the prepared dentin surface. Ideally, the degree of monomer conversion would be high enough that the acidic reaction would be self-limiting. The purpose of this study was to investigate the effect of light irradiance and source on the photopolymerization of three commercial dental adhesives by monitoring the double bond conversion as a function of time during and after irradiation. The photopolymerization curing efficiency of the commercial adhesives investigated in this study varied as a function of light source and distance. The use of LED performed better than the halogen light in terms of polymerization rate and degree of conversion for the commercial single-step, sixth generation adhesive, Adper Prompt. In contrast, polymerization of commercial single-bottle, fifth generation adhesive, Single Bond and One-Up Bond F, was mainly a function of exposure time, irrespective of the two light units or intensities.Journal of Biomedical Materials Research Part B Applied Biomaterials 03/2007; 80(2):440-6. · 2.31 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Posterior composite restorations have been in use for approximately 30 years. The early experiences with this treatment indicated there were more clinical challenges and higher failure rates than amalgam restorations. Since the early days of posterior composites, many improvements in materials, techniques, and instruments for placing these restorations have occurred. This paper reviews what is known regarding current clinical challenges with posterior composite restorations and reviews the primary method for collecting clinical performance data. This review categorizes the challenges as those related to the restorative materials, those related to the dentist, and those related to the patient. The clinical relevance of laboratory tests is discussed from the perspective of solving the remaining clinical challenges of current materials and of screening new materials. The clinical problems related to early composite materials are no longer serious clinical challenges. Clinical data indicate that secondary caries and restoration fracture are the most common clinical problems and merit further investigation. The effect of the dentist and patient on performance of posterior composite restorations is unclear and more clinical data from hypothesis-driven clinical trials are needed to understand these factors. Improvements in handling properties to ensure void-free placement and complete cure should be investigated to improve clinical outcomes. There is a general lack of data that correlates clinical performance with laboratory materials testing. A proposed list of materials tests that may predict performance in a variety of clinical factors is presented. Polymerization shrinkage and the problems that have been attributed to this property of composite are reviewed. There is a lack of evidence that indicates polymerization shrinkage is the primary cause of secondary caries. It is recommended that composite materials be developed with antibacterial properties as a way of reducing failures due to secondary caries. Post-operative sensitivity appears to be more related to the dentin adhesives' ability to seal open dentinal tubules rather than the effects of polymerization shrinkage on cuspal deflections and marginal adaptation.Dental Materials 02/2005; 21(1):9-20. · 3.77 Impact Factor