Effect of Different Application Techniques on Marginal Microleakage and Adaptation of Class II Cavities Restored with Different Bulkfill Composite Filling Materials: An In Vitro Study

Abstract

This is an in-vitro cross sectional study aimed to evaluate the effect of bulkfill and incremental placement techniques on microleakage and adaptation of class II cavity filled with three different bulkfill composite materials at occlusal and gingival margins. Standardized class II cavity was prepared in 192 human premolar teeth extracted for orthodontic purpose, The specimens were assigned to two main study groups corresponding to two different evaluation groups (A and B). The A group related to microleakage specimens, which were (n=120), and the B group related to adaptation specimens, which were (n=72). Each A and B groups were further randomly divided in to two main groups according to the two different application techniques (incremental and bulkfill). Each main group further subdivided into three subgroups for each technique, based on the different bulkfill restorative materials used in this study:-(1) Tetric®N-Ceram bulkfill (Ivoclar Vivadent), (2) Filtek™bulkfill flowable restorative material (3M ESPE), and (3) X-trafil®bulkfill (Voco). All cavities were etched, and the corresponding self-etch bond adhesive systems, Adhe SE One F (Ivoclar Vivadent), Scotch Bond Universal (3M Espe), and Futura bond DC (Voco) were applied. A stereomicroscope was used to evaluate microleakage, after immersion of the specimens in 0.1% methylene blue for 24 hours. Confocal microscopy was used to evaluate adaptation. Afterwards the specimens were thermocycled, then the data was analyzed using the Mann-Whitney U test. P < 0.05 was used to indicate statistically significant differences. Results showed no significant statistic difference in marginal microleakage among the different groups either by using incremental or bulkfill techniques at occlusal and gingival margins. X-trafil®bulkfill (Voco) showed the lowest score of microleakage in comparison to the other groups, and this happened when both application techniques were considered. The confocal microscopy results revealed that no significant differences in marginal adaptation were detected among the two application techniques (incremental and bulkfill) at gingival margins p=1.000 and the occlusal margins p=0.639 with the lowest gap width formation achieved by X-trafil® bulkfill composite among the three different bulkfill composite filling materials, while Filtek™ Flowable composite material had the highest gap width. Marginal microleakage and adaptation scores were not statistically different when different application techniques were applied. This study signifies that good marginal seal depends on the proper cavity preparation, good manipulation of filling materials and skill of the operator whatever was the application technique.