Nonrestorative treatment of discolored teeth: reports from an International Symposium.
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Dental Devices, Home Care↗
Biomedical subjects
H O Heymann
Publications and source records attributed to H O Heymann.
Nonrestorative treatment of discolored teeth: reports from an international symposium.
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Dental Devices, Home Care↗
Conservative concepts for achieving anterior esthetics.
The options in conservative approaches to anterior esthetics include several that are often forgotten in favor of more complicated procedures. This article explores many of those treatments, including recontouring, abrasion and veneers.
Dental Enamel↗
Mechanical properties of a new mica-based machinable glass ceramic for CAD/CAM restorations.
Machinable ceramics (Vita Mark II and Dicor MGC) exhibit good short-term clinical performance, but long-term in vivo fracture resistance is still being monitored. The relatively low fracture toughness of currently available machinable ceramics restricts their use to conservative inlays and onlays. A new machinable glass ceramic (MGC-F) has been developed (Corning Inc.) with enhanced fluorescence and machinability. The purpose of this study was to characterize and compare key mechanical properties of MGC-F to Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II glass ceramics. The mean fracture toughness and indented biaxial flexure strength of MGC-F were each significantly greater (p < or = 0.01) than that of Dicor MGC-Light, Dicor MGC-Dark, and Vita Mark II ceramic materials. The results of this study indicate the potential for better in vivo fracture resistance of MGC-F compared with existing machinable ceramic materials for CAD/CAM restorations.
Aluminum Silicates↗
Case-control study of non-carious cervical lesions.
An exploratory case-control study of non-carious cervical lesions was undertaken to examine the effects of a variety of risk factors. Candidate exposure variables were related to erosion, abrasion, and tooth flexure, the three principal putative causal mechanisms for cervical lesions. Because previous studies have tended to focus on specific causal mechanisms, evidence for a multifactorial etiology is inconclusive. Data describing exposure factors were obtained through clinical examination, dietary and behavioral questionnaires, and analysis of study casts from 264 subjects (137 cases, 127 control). Salivary data were also obtained for a subset of these subjects. Patient and tooth-level logistic regression models were constructed for the full subject group, and the subset with salivary data. For the two patient-level models, only exposures related to brushing entered. For tooth-level models, multiple exposures representing all three causal mechanisms were included in both models. The results suggest that non-carious cervical lesions do have a multifactorial etiology, and that multiple causal mechanisms may operate in the initiation and progression of individual lesions.
Adult↗
The clinical performance of CAD-CAM-generated ceramic inlays: a four-year study.
The authors conducted a long-term clinical study of 50 CEREC (Siemens AG) CAD-CAM inlay restorations in 28 patients. After four years, they found the inlays to rate very highly in color matching, interfacial staining, secondary caries, anatomic contour, marginal adaptation, surface texture and postoperative sensitivity. They monitored cement loss along the occlusal margins and found it to be relatively low, with an unusual decrease in measured cement wear from the third to the fourth year. The favorable results of this long-term clinical study of these CAD-CAM restorations portend significant success for this restorative approach.
Analysis of Variance↗
Bonding to enamel and dentin: a brief history and state of the art, 1995.
The acid-etch technique for bonding composite resins to enamel has revolutionized the practice of restorative dentistry. The ability of clinicians to bond restorative materials to enamel has fundamentally changed such diverse areas as cavity preparation, caries prevention, and esthetic treatment options. Although bonding of resin to dentin has proved to be a difficult challenge, ongoing advances are improving the reliability and predictability of dentinal adhesion. The purpose of this article is to provide a brief history of enamel and dentinal bonding, as well as an overview of the current state of the art.
Acid Etching, Dental↗
Confirmation of Leinfelder clinical wear standards.
OBJECTIVES: Accuracy of composite wear studies based on Leinfelder standards has been disputed. There are differences with other well-calibrated systems such as the M-L and Vivadent wear standards. The objective of this study was to reevaluate the margin height at key regions along the restoration margins for each of the 6 Leinfelder standards using laser profiling techniques. METHODS: The Leinfelder standards were profiled in parallel paths 100 microns apart and measured in x-y-z position every 20 microns along those paths using a laser profilometer. RESULTS: Rounding of cavosurface enamel margins from intraoral wear greatly increased the uncertainty of the true enamel margin location and step height measurements, precluding unequivocal measurements for standards #2 and #3. Values for other standards for the original report, newly measured means and standard errors, and measured ranges were: #4 (322 microns, 333 +/- 34 microns, 171-507 microns), #5 (382 microns, 459 +/- 44 microns, 202-649 microns), and #6 (493 microns, 584 +/- 91 microns, 315-1022 microns). There were no statistically significant differences (p < or = 0.10) between these and original values. Large standard errors may have obscured small differences that may exist. The Leinfelder cast conversion scale seems to be the correct relative magnitude. SIGNIFICANCE: Differences between Leinfelder casts and other standards may be due to differences in shadow production. Clinical wear may be systematically underestimated by other cast evaluation methods that have well-defined margins. This emphasizes the need for standard casts with margin morphology similar to the clinical casts being evaluated for wear.
Bicuspid↗
Non-carious cervical lesions.
Non-carious cervical lesions are commonly encountered in clinical practice and present in a variety of forms. A knowledge of the aetiology of these lesions is important for preventing further lesions, halting progression of lesions already present, and determining appropriate treatment. The most commonly cited aetiological factors thought to lead to the development of cervical lesions are erosion, abrasion and tooth flexure. Evidence supports a multifactorial aetiology for non-carious cervical lesions. The purpose of this paper is to review the evidence for each of these aetiological factors as it relates to the development of non-carious cervical lesions. Specific features of cervical lesions linked to these factors, including their morphology, location, prevalence and distribution by age and sex will be discussed. Suggestions for future research into the cause and prevention of non-carious cervical lesions will be presented.
Dental Occlusion, Traumatic↗
Response of normal and tetracycline-stained teeth with pulp-size variation to nightguard vital bleaching.
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Adult↗
Update on dental composite restorations.
The rapidly changing area of dental composites can confound practitioners if they ignore material selection and correct techniques. The complex steps involved in placing composite restorations are explained to avoid potential problems and ensure complete success.
Composite Resins↗
Two ceramic materials compared for the production of CEREC inlays.
Two ceramic materials, MGC Dicor and Vitablocs Mark II, were compared in vitro for the quality of fit of CEREC inlay restorations. The inlays made from Vitablocs Mark II fitted the inlay preparation significantly better than those made from MGC Dicor.
Ceramics↗
Current concepts in dentin bonding: focusing on dentinal adhesion factors.
With greater need for treating root surface lesions, dentinal adhesives are more in demand. For successful treatment, all factors--dentin, tooth, patient and materials--must be considered.
Age Factors↗
How dentists classified and treated non-carious cervical lesions.
All North Carolina general dentists were shown color photographs of three non-carious cervical lesions. A fourth picture showed cervical caries. Respondents were asked how they defined each lesion, its cause, treatment and frequency of appearance in practice. Cervical caries was identified and treated by almost all responding dentists, but they applied more varied terms, causes and treatments to non-carious defects.
Clinical Competence↗
Toxicity of two carbamide peroxide products used in nightguard vital bleaching.
This study evaluated the effects of two generic classes of 10% carbamide-peroxide (CP) oxygenating agents (currently under clinical assessment for nightguard vital tooth bleaching) for lethality and genetic mutation after oral administration to mice, and for cellular cytotoxicity to mouse fibroblasts in vitro. The single dose LD50 values for a non-carbopol-containing CP (Gly-Oxide) and a carbopol-containing CP (Proxigel) in mice were found to be 143.8 mg/kg and 87.2 mg/kg, respectively. Genotoxicity, as measured by the Mouse Micronucleus test for mutagenicity, was negative for both 10% CP agents in comparison with positive and negative controls. Cytotoxicity as measured in the L929 fibroblast lysis assay resulted in 50% killing of L929 fibroblasts at 0.62 for the non-carbopol-containing CP and 1.88 mmol/L for the carbopol-containing CP. Both 10% CP agents were compared with seven widely-used dental products in the L929 fibroblast lysis assay and found to be no more toxic than these products.
Analysis of Variance↗
Protection hypothesis for composite wear.
Significant occlusal wear occurs on posterior composite restorations in areas without direct contact with opponent teeth (contact-free wear) in addition to wear at the contacts. Recent research has indicated that all occlusal posterior composite surfaces wear, and those surfaces show decreasing wear rates over time. This provides more evidence for an earlier theory proposed by Jørgensen et al. (1979) that composite contact-free wear is a function of access and attrition caused by small particles in the food bolus. This hypothesis is now called the "protection theory" or "protection hypothesis" for wear. Macroscopic protection or "sheltering" from wear is provided by cavity preparation walls. Microscopic protection against resin matrix wear is provided by filler particles that are close together. Clinical evidence supporting the protection hypothesis comes from recently confirmed low wear rates for microfill and hybrid composites. The objective of this work was to calculate the minimum inter-particle spacing required for microscopic protection (wear resistance) for composites based on assumptions of packing fractions (0.68) with small particles (0.02 microns radius) for dispersed versus agglomerated conditions. An inter-particle spacing (IPS) of < 0.10 microns was assumed to afford wear protection. The results are that only 1.5-6.0 volume percentage microfiller is theoretically required to generate an IPS of 0.1 micron for composite microscopic protection. However, microfiller particles are suspected to agglomerate into clusters. Modified calculations for that effect indicate that at least 35% filler is required to provide microscopic protection. This effect explains much of the 3 to 5 year clinical research results for microfills and hybrids.(ABSTRACT TRUNCATED AT 250 WORDS)
Composite Resins↗
Examining tooth flexure effects on cervical restorations: a two-year clinical study.
This study evaluated the clinical performance of dentinal adhesives in seven various material/technique combinations. No statistically significant differences were observed among the restorative combinations, or among technique variables after two years in terms of retention, sensitivity or USPHS categories. However, other factors related to tooth flexure--such as occlusal stress, patient age, restorative material and restoration location--showed statistically significant associations with retention failures. These results support a tooth flexural theory of restoration retention.
Acid Etching, Dental↗
Contributing co-variables in clinical trials.
To accurately compare Class V dentinal bonding studies, it is essential to critically classify the effects of the intraoral location and age of the patient on the retention of resin composite restorations. A mathematical formula for normalization combined with the Weibull analysis also is proposed that could provide CL50 values for the clinical longevity of adhesive restorations.
Adult↗