A comparative research of the effects of laser and conventional etching methods on bond strength and microleakage in pits and fissure sealant applications under in-vitro conditions.

The aim of this study was to comparatively research the bond strength and microleakage of resin and polyalkenoate based fissure sealants made by applying or not applying the bonding agent following Er:YAG laser and conventional etching. In the study, 299 intact third molar teeth extracted in 6 months were used. Teeth were seperated into 13 groups, in which n=16 for microleakage and n=7 for bond strength: Laser+Clinpro® (G1), laser+acid+Clinpro® (G2), laser+acid+bond+Clinpro® (G3), laser+bond+Clinpro® (G4), acid+Clinpro® (G5), acid+bond+Clinpro® (G6), bond+Clinpro® (G7), laser+Fuji Triage® (G8), laser+bond+Fuji Triage® (G9), laser+conditioner+Fuji Triage® (G10), laser+conditioner+bond+Fuji Triage® (G11), conditioner+Fuji Triage® (G12) and direct Fuji Triage® (G13). The teeth were thermocycled (1000X, 5-55°C) and were covered with two layers of nail polish, leaving a 1mm gap around their fissure sealant margines after their apices were blocked by composite. The teeth were kept in % 0.5 basic fuchsine for 24 hours, washed under tap water and embedded in acryl blocks. The teeth in acryl blocks, were cut buccolingually through 3 parallel parts by a diamond knife (Isomet, Buehler®; Lake Bluff, IL, USA) and were evaluated under a stereomicroscope (Leicamicrosystems® stereo microscope, Ltd.Stereo and microscope systems; Heerburg, Switzerland). In the bond strength test, the teeth were embedded into acryl blocks, leaving their vestibule or lingual enamel surfaces open. After the surface treatment was complete based on the groups, 2,5 mmx3,5 mm fissure sealants were prepared with the help of a specially prepared plexiglass mould. Universal testing device (Shimadzu KgN50®. Shimadzu Corp. Kyoto, Japan) was used for the shear bond strength test of the specimens which were kept in distilled water for 24 hours. 0,5 mm/min force had been applied until the specimens were broken. Surfaces of the specimens were examined under a stereomicroscope (Leicamicrosystems® stereo microscope, Ltd.Stereo and microscope systems; Heerburg, Switzerland) by enlarging them x10 and the specimens selected from the groups were evaluated by a scanning electron microscope (SEM) (Jeol JSM® 5200, Kyoto, Japan). The acquired data was analyzed by SPSS 19.0 (SPSS Inc®. Chicago, IL, USA) statistics software; for microleakage Kruskal-Wallis and Mann Whitney U test (p<0,05) and for bond strength Shapiro-Wilk, Oneway Anova, Levene, Welch and Dunnett T3 test was performed(p<0,05). According to microleakage test findings; laser+acid+Clinpro®, laser+acid+bond+Clinpro®, laser+bond+Clinpro® and acid+Clinpro® groups were found to have less statistically significant scores compared to the other groups (p<0,05). According to the bond strength findings; acid+Clinpro®, acid+bond+Clinpro®, laser+acid+Clinpro® groups had a more statistically significant bond strength compared to the other groups (p<0,05). As a result; when microleakage and bond strength findings were evaluated together, resin based fissure sealants had significantly lower leakage compared to glass polyalkeonate based sealants and under the light of these findings it was found that laser and/or bonding agent usage does not suffice to meet the need of acid etching and conventional etching method still has better results and methods with more stages prolong the duration of the treatment, thus should not be suggested for clinical applications.