Adesão dentinária: efeito do grau de mineralização e do tempo de condicionamento ácido

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em OdontologiaObjetivos: verificar a capacidade de união ao substrato dentinário hipermineralizado com dois tempos de condicionamento ácido. Material e métodos: Trinta molares humanos com cáries oclusais crônicas foram cortados transversalmente, polidos até lixa 600, expondo a dentina esclerótica na porção central. O ácido fosfórico 35% (3M) foi usado por 15s ou 30s, e o sistema SingleBond+Z250(3M) foram aplicados. Depois de 24 h em água, os dentes foram cortados em duas direções perpendiculares com um disco diamantado para obter-se os filetes com uma seção de aprox. 0.7mm2 (n=25). Um exame visual foi conduzido para dividir os filetes em dois grupos: dentina esclerótica (G15E e G30E) e normal (G15N e G30N). Os filetes foram colados em um dispositivo (Bencor) e a resistência de união por microtração (m-TBS) foi medida. Os dados foram analisados por ANOVA 2 e teste t. A dureza Knoop (KHN) da porção dentinária de todos os filetes foi medida e os dados entre a dentina esclerótica e normal foram comparados com teste t. Resultados: As médias (±DP) de m-TBS foram: G15E=56,4(±14,9), G15N=69,7(±17,2), G30E= 63,2(±15,6) e G30N=67,7(±13,3). O teste t mostrou que G15N apresentou superior m-TBS quando comparado com G15E (p=0,0016). ANOVA 2 mostrou que a m-TBS na dentina normal foi maior do que na esclerótica. A dureza da dentina esclerótica foi maior do que na normal. Conclusões do experimento: O maior conteúdo mineral na dentina esclerótica dificulta a união a este substrato, resultando em mais baixa m-TBS. Mas, a duplicação do tempo de condicionamento resulta em uma m-TBS similar à dentina normal

Correlation between clinical performance and degree of conversion of resin cements: a literature review

AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used

Color difference between the vita classical shade guide and composite veneers using the dual-layer technique

The purpose of this in vitro study was to evaluate the color difference between the Vita Classical Shade Guide and composite veneers using the dual-layer technique. Thirty samples were fabricated using a custom-made mold (Easy Layering Shade Guide Kit

Correlation between clinical performance and degree of conversion of resin cements: a literature review

However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photocured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. 6SHFL¿F PHDVXUHV DUH WR EH WDNHQ WR HQVXUH D KLJKHU '& RI WKH OXWLQJ V\VWHP WR EH XVH

CLOCK polymorphisms in attention-deficit/hyperactivity disorder (ADHD) : further evidence linking sleep and circadian disturbances and ADHD

Circadian and sleep disorders, short sleep duration, and evening chronotype are often present in attention-deficit/hyperactivity disorder (ADHD). CLOCK, considered the master gene in the circadian rhythm, has been explored by few studies. Understanding the relationship between ADHD and CLOCK may provide additional information to understand the correlation between ADHD and sleep problems. In this study, we aimed to explore the association between ADHD and CLOCK, using several genetic markers to comprehensively cover the gene extension. A total of 259 ADHD children and their parents from a Brazilian clinical sample were genotyped for eight single nucleotide polymorphisms (SNPs) in the CLOCK locus. We tested the individual markers and the haplotype effects using binary logistic regression. Binary logistic and linear regressions considering ADHD symptoms among ADHD cases were conducted as secondary analysis. As main result, the analysis showed a risk effect of the G-A-T-G-G-C-G-A (rs534654, rs1801260, rs6855837, rs34897046, rs11931061, rs3817444, rs4864548, rs726967) haplotype on ADHD. A suggestive association between ADHD and rs534654 was observed. The results suggest that the genetic susceptibility to circadian rhythm attributed to the CLOCK gene may play an important role on ADHD

Adesão à dentina: efeito do tempo de condicionamento ácido e da idade dentinária

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em Odontologia.O objetivo foi verificar se há diferença na capacidade de união ao substrato dentinário envelhecido quando comparado com o jovem; e, se o aumento do tempo de condicionamento poderá resultar em uma maior resistência de adesão a este substrato envelhecido, sem prejudicar a união ao substrato jovem. Foram realizados testes de resistência de união, verificação da dureza dentinária e microscopia eletrônica de varredura da interface adesiva. A dentina envelhecida condicionada por 15s obteve resistência de união estatisticamente menor que todos os outros grupos. A dureza da dentina envelhecida foi maior do que a dentina jovem. O maior conteúdo mineral na dentina envelhecida dificulta a união, resultando em mais baixa m-TBS quando o condicionamento é feito por apenas 15s. Por outro lado, a duplicação do tempo de condicionamento resulta em mais adequada adesão à dentina envelhecida alcançando médias similares à dentina jovem

Hydrofluoric Acid – Simple Things You May Do Not Know About Something You Are So Habituated To Use

Hydrofluoric Acid (HF) acid usually is used to etch the internal surface of the ceramic restoration. This acid increases surface relief in micromechanical bonding of resin cement to ceramic restoration Pre-treatment conditioning with HF in feldspathic ceramic and leucita reinforced glass-ceramic will result in an internal surface with white-opaque appearance. In this brief new perspective article we would discuss some important issues regarding HF use in dentistry