Diametral compressive bond strength of composite resin associated with an adhesive system in incremental filling technique.

AIM: The aim of this in vitro study was to evaluate the diametral compressive bond strength between Charisma or TPH composite resin after association or not to an adhesive system in incremental filling technique. METHODS: Twenty cylinders of each composite resin brand were fabricated using a Teflon matrix and divided into four groups, according to the numbers of adhesive layers applied: group 1 Control without adhesive; group 2 one layer; group 3 two layers and group 4 three layers. The bonding system Adper Single Bond was used between composite resin increments. Diametral compression assays were carried out in an EMIC-MEM 2000 universal testing machine, adjusted at 1 mm/min. ANOVA and Tukey's test were used in the statistical analysis. RESULTS: The mean strengths and standard deviations for each group were: Charisma 1= 38.26+/-2.38; 2=46.56+/-2.38; 3=40.57+/-2.38; 4=36.87+/-2.38 (2>1=3=4; P<0.05) and TPH 1=52.17+/-2.38; 2=52.23+/-2.38; 3=44.68+/-2.38; 4=44.11+/-2.38 (1=2>3=4; P<0.05). CONCLUSIONS. It was concluded that TPH presented higher means of compressive bond strength than Charisma, and the association of an adhesive system between the increments may influence the diametral compressive bond strength of composite resins.

Analysis of the diametral compressive bond strength between composite resin and amalgam in different stages of oxidation.

AIM: Amalcomp is a technique that combines composite resin to amalgam in restorative procedures to improve esthetics and minimize the negative effects of polymerization on dental tissues. The objective of this in vitro study was to measure the diametral compressive bond strength between Fill Magic composite (Vigodent) versus Permite (DFL) or Velvalloy (SS White) amalgams in different oxidation stages. METHODS: Twenty-four cylinders of each amalgam brand were fabricated using a Teflon matrix and divided into 3 groups according to the immersion period in artificial saliva for oxidation: A (1 day), B (7 days) and C (30 days). After immersion, the amalgam cylinders were bonded to the composite specimens using the Scotch Bond Multi Use Plus (3M) bonding system. Diametral compression assays were then carried out in an EMIC-MEM 2000 universal testing machine set to 0.5 mm/min. Statistical analysis was performed using ANOVA and Tukey's test. RESULTS: The mean recorded strength (MPa) for each oxidation group was: A=9.71, B=8.21 and C=6.98 (A>B = C; P<0.01). Permite (7.24) provided significantly less adhesion to the composite than Velvalloy (9.36; P<0.05). There was no interaction between the factors alloy, resin and time. CONCLUSIONS: Under the conditions of this study, the less oxidized amalgam showed the greatest diametral compressive strength values.