Cavity Resin Research Articles

Restaurações indiretas em resina composta em cavidades com diferentes profundidades: Relato de caso

Restaurações indiretas em resina composta são comumente usadas em dentes posteriores nas diferentes cavidades, permitindo maior resistência ao desgaste, adaptação marginal, estabelecimento de contatos proximais e maior dureza, uma vez que passam pelo processo de termopolimerização. O objetivo desse estudo é relatar um caso clínico de substituição de restaurações em amálgama por restaurações indiretas em resina composta em cavidades com diferentes profundidades. Paciente, sexo feminino, 34 anos, procurou a clínica odontológica de uma instituição privada, queixando-se de insatisfação estética nas restaurações em amálgama nos dentes 45, 46 e 47. Após exame clínico, devido à extensão das cavidades, foi sugerido a realização de restaurações indiretas em resina composta nos três elementos. Após a remoção do amalgama, com ponta diamantada, avaliou-se as profundidades das cavidades dos dentes. No dente 45, realizou-se tratamento endodôntico e instalação de pino de fibra de vidro. No dente 46 foi realizado um capeamento pulpar indireto e no dente 47 não foi realizado nenhum tratamento de proteção pulpar. Posteriormente, os dentes foram preparados para restaurações indiretas com ponta diamantada #3131, em seguida, foram moldados com silicone de adição, prosseguindo com vazamento do molde com gesso tipo IV. O modelo foi troquelizado pela técnica de duplo vazamento e as restaurações em resina composta foram confeccionadas sobre o modelo. Na sessão seguinte, as restaurações foram cimentadas com cimento resinoso dual autoadesivo. Por fim, foi realizado o ajuste oclusal, seguido do acabamento e polimento. As terapêuticas empregadas foram eficazes para recuperar a forma anatômica e estética dos elementos dentários envolvidos.

Bond Durability of Er:YAG Laser-Prepared Primary Tooth Enamel

This study evaluated in vitro the influence of thermocycling and water storage (WS) on the shear bond strength (SBS) of composite resin in cavities prepared in primary tooth enamel with conventional bur or Er:YAG laser. The test surfaces were obtained from 48 primary molars and randomly assigned to 2 groups (n=24), according to cavity preparation: A: bur-preparation and B: Er:YAG laser irradiation. The specimens were restored with an etch-and-rinse adhesive system and composite resin. Each group was divided into 4 subgroups (n=6) according to WS duration and number of thermal cycles (TCs): I: 24 h WS/no thermocycling; II: 7 days WS/500 TCs; III: 1 month WS/2,000 TCs; IV: 6 months WS/12,000 TCs. The specimens were tested to failure in shear strength at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by two-way ANOVA and Tukey's test. SBS means (S.D.) in MPa were: AI: 17.45 (2.03), AII:16.38 (1.49), AIII: 6.88 (0.66), AIV: 7.77 (1.53), BI: 12.32 (0.99), BII: 15.37 (2.24), BIII: 15.05 (2.01) and BIV-5.51 (1.01). WS duration and number of TCs influenced significantly the SBS values only for BIV (p<0.05). AI presented the highest SBS value, which was statistically similar to those of AII, BII and BIII. In conclusion, the adhesion of an etch-and-rinse adhesive to Er:YAG laser-irradiated primary tooth enamel was affected by the methods used to simulate degradation of the adhesive interface only when 6 months WS/12,000 TCs were employed.

Shrinkage Analysis of a Light-Cured Composite Resin in Cavities by X-ray CT Images

Shrinkage Analysis of a Light-Cured Composite Resin in Cavities by X-ray CT Images

Shrinkage forces due to polymerization of light-cured dental composite resin in cavities

A new method has been developed for determining shrinkage forces due to polymerization of light-cured dental composite resin in artificial cylindrical cavities. The cavities were fabricated in stainless steel plates, and shrinkage forces were measured using a load cell inserted from the rear of the plate in place of the floor of the cavity. The cavities were 3 mm in diameter, and depths varied from 0.5 to 3.5 mm to study the effect of light intensity. Cavities were filled with a composite resin after being prepared with a bonding agent and were then irradiated for 20 s with a light-curing unit at a power of 300 mW/cm 2. To study the effects of boundaries, two conditions were employed: a free surface condition without any restriction on the top surface of the cavity, and a constrained surface condition in which the top surface of the resin was bonded to a 1 mm thick transparent polymethyl methacrylate (PMMA) plate. The shrinkage forces were measured as functions of time and the cavity depth, and the following results were obtained. For both conditions, the force increased with time, mostly during the irradiation stage (20 s), and then increased slightly after the irradiation. The force measured at 300 s increased gradually with the cavity depth and exhibited a maximum value before decreasing gradually. The cavities with constrained surfaces yielded much greater shrinkage forces for any given cavity depth than those with free surface conditions.

Effect of dentin adhesives on contraction of restorative resins in cavities surrounded by acid-etched enamel

Enamel-surrounded cavities prepared in extracted human teeth were treated with an enamel-bonding agent, one of two commercial dentin adhesives (Scotchbond 2 and Tenure), or one of two recent modifications of the Gluma system. In all cases the enamel margins were subjected to some form of acid etching. The cavities were filled with one of two different light-cured posterior resins, and the wall-to-wall polymerization contraction was assessed in the enamel surface level and, after grinding, measured and presented as linear shrinkage in the dentin surface level. The linear shrinkage varied from 0.66% in the control group, in which only composite resin was applied, to 0.28% in a group in which the cavities were pretreated with dentin adhesive. No difference could be demonstrated between the dentin adhesives or between the dentin adhesives and the enamel-bonding agent.