The evaluation of mikroleakage in different restorative materials in primary teeth

Microleakage is the one of the most important problems resulted from different reasons such as material's behaviour, setting procedure, differences between tooth and fillling material...etc in operative dentistry. Because of the dramatic effects of microleakage, most of the investigations have been focused on the elimination of this problem. Since the last four decades, although several materials and restorative techniques have been advocated to eleminate the microleakage, today neither current materials nor techniques could not been completely reduced this problem. However, to eliminate the microleakage, recently introduced dentinal bonding agents seem hopefull. The purpose of this study was to compare marginal leakage and adaptation of four different restorative techniques in primary teeth. Fourty class 5 cavities were prepared in extracted human primary molars. All the cavities were located in the cervical third of the buccal aspects. After finishing the preperations, the teeth were divided into 4 groups: 1) Lining with GIC and finishing with high copper amalgam, 2) Lining with GIC, applying of Panavia 21 and finishing with high copper amalgam, 3) Lining with GIC, total etching all of the cavity walls and GIC surface and finishing with a hybride composite resin and, 4) Lining with GIC, total etching all of the cavity walls and GIC surface, applying of Panavia 21 and finishing with a hybride composite resin A 1mm 45o bevel was placed at the enamel margin in only composite cavities before the restorations, the restorations filled with composite resin were polished with soflex discs and others were finished with stone and rubber polishing burs. The teeth were then thermocycled between 54 oC and 604 oC for 250 cylces and stored in the distilled water at the 37 oC for three days. After the storage procedure, the teeth were sealed with nail polish up to 1 mm from the margins of the restoration and placed in %2 Methilen Blue dye solution in 24 hours. The teeth were then sectioned mesio-distally through at the middle of the restoration. One of the half was used to evaluate microleakage and other was used to SEM investigation. Microleakage was evaluated for the enamel and dentin margins using the following scale: 0= no leakage, 1= leakage of the dye solution less then 1/3 of the cavity wall, 2= leakage of the dye solution between 1/3 and 2/3 of the cavity wall, 3= leakage of the dye solution reaching the axial wall and 4= leakage of the dye solution along the axial wall 5= leakage of the dye solution all of the cavity walls and toward to pulp. The techniques were compared to each other using the Kruskal-Wallis (one way variance analyses) test. The micromorphology of the tooth/restoration and both of two materials interface was analysed with SEM and gaps up to 10 m were measured. All restoration types showed microleakage ranging from less to severe. Group 3 (GIC+Composite resin) had significantly less and Group 2 (GIC+Panavia 21+High Copper Amalgam) had significantly most microleakage in four groups. Panavia 21 was found to be increasing the microleakage. These results showed that glass ionomer lining materials have a good potential to reduce the microleakage and currently avaliable dentinal bonding agents must be improved with respect to elimination of microleakage.