Scielo RSS <![CDATA[Journal of Applied Oral Science]]> http://www.scielo.br/rss.php?pid=1678-775720040005&lang=en vol. 12 num. SPE lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[<b>Editorial</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-77572004000500001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Alternatives in polymerization contraction stress management</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-77572004000500002&lng=en&nrm=iso&tlng=en Polymerization contraction stress of dental composites is often associated with marginal and interfacial failure of bonded restorations. The magnitude of the stress depends on the composite's composition (filler content and matrix composition) and its ability to flow before gelation, which is related to the cavity configuration and curing characteristics of the composite. This article reviews the variations found among studies regarding the contraction stress testing method, contraction stress values of current composites, and discusses the validity of contraction stress studies in relation to results from microleakage tests. The effect of lower curing rates and alternative curing routines on contraction stress values is also discussed, as well as the use of low elastic modulus liners. Moreover, studies with experimental Bis-GMA-based composites and recent developments in low-shrinkage monomers are described. <![CDATA[<b>Water movement across bonded dentin - too much of a good thing</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-77572004000500003&lng=en&nrm=iso&tlng=en Over the last decade, the classic concept of 3-step bonding to dental tissues has developed rapidly to more user-friendly, simplified adhesive systems. These comprise the total-etch 2 step, self-etch 2step and the self-etch "all-in-one" adhesives. These adhesives carry along with simplicity some characteristics that are relevant to their efficacy in providing long-lasting bond stability. They share with the glass ionomer cements a class of materials that have high affinity for water. Such hydrophilicity renders such adhesives very permeable and denies their ability to hermetically seal dentin surfaces. Additionally, the water flux across simplified adhesives may compromise bonding in certain circumstances and their durability in the oral environment. This paper presents evidences of the water transport across simplified adhesive systems and glass ionomer cements and relates them with clinical implications of the phenomenon. <![CDATA[<b>Dental ceramics and the molar crown testing ground</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-77572004000500004&lng=en&nrm=iso&tlng=en All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior), and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above. <![CDATA[<b>39º Encontro GBMD - Grupo Brasileiro de Materiais Dentários</b>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-77572004000500005&lng=en&nrm=iso&tlng=en All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior), and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above.