Study provides new insight on dentin caries
USA: The methods used to assess the outcomes of remineralization of dentin were critically evaluated by Professor Grayson Marshall, President-elect of the American Association for Dental Research. Currently, the most used assessment methods fall either into quantitative analysis of the mineral content of the remineralized structures or dry measurements of their mechanical properties.
The study carried out by Dr Marshall’s group emphasizes that a more appropriate endpoint to evaluate the effectiveness of remineralization in dentin should be associated with the recovery of the mechanical properties of the hydrated tissue, which is presumed to correlate well with its overall functionality.
“Significant progress has been made regarding enamel caries. We know that early enamel caries can be reversed through a combination of diet, hygiene and chemical treatments such as fluoride. However, once the caries reaches the inner dentin layer of the tooth, dentists normally surgically intervene by removing the demineralized dentin and must restore the lost tissue with a restorative material (filling). Dentin caries proceeds more quickly than enamel caries since dentin contains much less mineral and the mineral is of much smaller size and is more soluble,” explained Professor Marshall, who is chair of the Division of Biomaterials and Bioengineering, vice-chair at the Department of Preventive and Restorative Dental Sciences at the University of California, San Francisco.
As a result, he feels the efforts to reverse the process by remineralizing the lesion are not as well developed as for enamel caries. “We have gained some insight into the structure of dentin and dentin caries that suggests that a portion of the demineralized dentin may contain remnant mineral nuclei that can serve to assist remineralization. Most current dentin caries remineralization logically depends on measurement of new mineral added to the structure, but we have evidence that it is important to replace the mineral in close association with the remaining organic matrix (collagen fibrils),” Marshall added. Since a prime function of teeth depends on their mechanical properties he suggests in the paper that measurement of the restoration of mechanical properties of the dentin is important in evaluating remineralization treatments in dentin.
The paper goes on to say that the measurement of mechanical properties of remineralized caries lesions is an important indicator of successful remineralization treatment and measurements of newly formed mineral alone should not be relied on, because it may not indicate the correct incorporation of mineral in the remineralized tissues. “Furthermore, we have found that such measurements are most revealing when performed on the hydrated tissues. In this work we demonstrated the importance of using these wet measurements, since the same measurements done on dry tissues can be misleading,” he said.
He believes this work will provide new methods for evaluating new treatments of dentin caries and that these treatments can be evaluated in the laboratory prior to clinical application and should enhance the potential for clinical success.
“Eventually we hope that applications of these insights will lead to more conservative treatment of dentin caries and will allow fewer or smaller fillings to the benefit of patients. We are currently using these methods to evaluate various treatments designed to restore the hydrated mechanical properties of both artificial and natural caries,” he concluded.
Full article
‘Biomechanical Perspective on the Remineralization of Dentin’ Caries Research 43 (1) 70-77
Read the article as it appeared in Apex
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USA: The methods used to assess the outcomes of remineralization of dentin were critically evaluated by Professor Grayson Marshall, President-elect of the American Association for Dental Research. Currently, the most used assessment methods fall either into quantitative analysis of the mineral content of the remineralized structures or dry measurements of their mechanical properties.
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Germany: Researchers from the Fraunhofer Institute for Mechanics of Materials (IWM) in Freiburg have discovered a way to simulate the tension created by shrinkage after curing of filling material in dental restorations. Research assistant, Dr Christof Koplin explains: “Until now, it has not been possible to establish a theoretical model of the hardening process. The tension occurring in the material always depends on the shape of the cavity, and can vary widely by a factor of up to ten, particularly at the edges.”
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Following the success of the Minimum Intervention Symposium at the 2007 FDI Congress in Dubai, GC’s most recent session took the concept to a new level in the general dental practice. Hosted in Stockholm, Sweden, at the FDI’s 2008 Congress, the symposium aimed to equip practitioners with a clear strategy for implementing the MI approach in daily routines.
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Dr Elmar Reich serves on the FDI Education Committee, has a dental practice in Biberach, Germany, and is the scientific coordinator of the GC MI Advisory Board. He opened his dental practice in 2004 with a clear goal of practising according to the Minimum Intervention philosophy. We asked him a few questions about how he achieves this goal.
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CAM (computer-aided manufacturing) and CAD (computer-aided design)/CAM systems facilitate the use of zirconia substructure materials for all-ceramic fixed partial dentures. An in vitro study, led by Dr Florian Beuer from the Department of Prosthodontics at Ludwig-Maximillians University in Munich, Germany, compared the precision of fit of frameworks milled from semi-sintered zirconia blocks that were designed and machined with two CAD/CAM and one CAM system. Results showed that CAD/CAM systems were more precise than the CAM system. Dr Beuer told Dental Learning Hub more about the study.
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Trauma to anterior teeth in children could become a long-term problem to dental health. To a large extent, the management actions of the dentists involved determine the clinical outcome and these actions are related to their levels of knowledge. A recent study investigated dentists' management of traumatic injuries to maxillary permanent incisors in children in Victoria, Austalia. Overall, the respondents to the survey demonstrated only a moderate level of knowledge. Dr Thai Yeng explained the significance of the research and how the knowledge gap can be addressed.
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Research conducted at Universidade Federal de Pernambuco in Recife, Brazil analysed the images sites of fracture initiation and slow crack propagation in a fiber reinforced composite using optical coherence tomography (OCT). Drs Ana Braz and Anderson Gomes from the university’s Graduate Programme in Odontology, concluded that OCT images provide a superior insight into crack propagation, which cannot be seen by the naked eye. By using OCT the possibility of analyzing fracture propagation both thoroughly and quantitatively opens up possibilities for further quantitative studies. They told Dental Learning Hub about the study.
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