The aim of this study was to evaluate in vitro the hardness and shrinkage of a pre-cooled or preheated hybrid composite resin cured by a quartz-tungsten-halogen light (QTH) and light-emitting diode (LED) curing units. The temperature on the tip of the devices was also investigated. Specimens of Charisma resin composite were produced with a metal mold kept under 37°C. The syringes were submitted to 4°C, 23°C, and 60°C (n=20) before light-curing, which was carried out with the Optilux 501 VCL and Elipar FreeLight 2 units for 20 seconds. The specimens were kept under 37°C in a high humidity condition and darkness for 48 hours. The Knoop hardness test was carried out with a 50 gram-force (gf) load for 10 seconds, and the measurement of the shrinkage gap was carried out using an optical microscope. The data were subjected to analysis of variance and the Games-Howell test (α=0.05). The mean hardness of the groups were similar, irrespective of the temperatures (p>0.05). For 4°C and 60°C, the top surface light-cured by LED presented significantly reduced shrinkage when compared with the bottom and to both surfaces cured by QTH (p<0.05). It was concluded that the hardness was not affected by pre-cooling or preheating. However, polymerization shrinkage was slightly affected by different pre-polymerization temperatures. The QTH-curing generated greater shrinkage than LED-curing only when the composite was preheated. Different temperatures did not affect the composite hardness and shrinkage when cured by a LED curing unit.
This in vitro study evaluated the Knoop hardness of the composite resins Charisma (C) and Durafill VS (D) polymerized in 3 different conditions: at room temperature (A) (23 +/- 1 degrees C); refrigerated at 4 +/- 1 degrees C and immediately photo-activated after removal from the refrigerator (0); and, refrigerated at 4 +/- 1 degrees C and photo-activated after a bench time of 15 min at room temperature (15). One hundred and twenty specimens (4 mm diameter and 2 mm depth) were made using a stainless steel mold and following manufacturer's instructions. All specimens were tested immediately after polymerization (I) and after 7 days of water storage in the dark at room temperature (7d). The data were subjected to ANOVA and post-hoc Tukey's test (alpha=0.05). On the top surface, C(AI) was statistically similar to C(15I) and D(AI) to D(15I) (p>0.05). On the bottom surface, C(AI) presented higher hardness values when compared to COI and C(15I) (p<0.05). The D groups showed no significant differences (p>0.05) on the bottom surfaces for any tested polymerization condition. After 7 days of storage, the Knoop hardness decreased significantly (p<0.05) for groups C(7d) and D(7d) except for C(07d), which was not different from C(OI) at either surface (p>0.05). D(07d) showed higher Knoop hardness (p<0.05) values on the top surface when compared to the other groups.
Introduction and Objective: Techniques for aesthetic purposes are being frequently used in dental practice due to social context. These techniques can be used to correct concomitant disharmonies in smile. This clinical case aimed to provide a harmonious smile combining the techniques of gingivoplasty and direct veneers on the maxillary anterior teeth. Case report: The gingivoplasty with clinical crown augmentation sought to correct defects present in toothgingival anatomy, resulting in a realignment of the gingival contour. Conclusion: The direct veneer technique with composite resins was elected for closing the interincisal diastema and correction the size of the involved teeth, providing a more aesthetic dental anatomy.
Ensino, pesquisa e contribuições científicas em odontologia -Volume I está licenciado sob CC BY 4.0.Esta licença exige que as reutilizações deem crédito ao criador. Ele permite que os reutilizadores distribuam, remixem, adaptem e construam o material em qualquer meio ou formato, mesmo para fins comerciais. O conteúdo da obra e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores, não representando a posição oficial da Editora Amplla. É permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores. Todos os direitos para esta edição foram cedidos à Editora Amplla.
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