[Influence of different bonding agents on marginal sealing quality of amalgam restorations].

Introduction: Although advanced adhesive systems are in use, marginal microleakage is one of the greatest problems of contemporary restorative dentistry.

Objective: The aim of this in vitro study was to evaluate the influence of different bonding agents on the marginal sealing quality of class II amalgam restorations.

Methods: Forty freshly extracted human premolar and molar teeth were divided into four groups with 10 teeth in each one. Class II preparations were prepared and different adhesives were applied as follows: group I--Amalgam Liner (Voco); group II--ONE-STEP PLUS (Bisco); group III--PQ 1 (Ultradent). Group IV was used as a control, without any bonding agent. Amalgam (Cavex Non Gamma 2, Cavex) was hand-condensed into each preparation. Specimens were thermocycled 200 times at the following temperatures: 5-7 degrees C, 37 degrees C and 57-59 degrees C, and were then immersed into 1% solution of gentian violet for 72 hours. The teeth were sectioned longitudinally and microleakage was graded in the area of the gingival and occlusal quantity rim using a binocular magnifying glass with 25 times magnification.

Results: The highest microleakage was recorded in the Amalgam Liner group; 1526.0 microm at the gingival wall and 694.5 microm at the occlusal cavity wall. The lowest dye penetration was observed in the PQ1 group; 589.5 microm at the gingival wall, and 599.9 microm at the occlusal wall of the restoration. ANOVA test showed that there was a statistically significant difference of dye penetration values at the gingival wall among all examination groups (p < 0.01). No statistically significant differences were found comparing microleakage values at the occlusal wall.

Conclusion: Results of this study showed that the best marginal sealing was accomplished by using the PQ1 bonding agent.