ABSTRACT
The hard tissue erbium lasers have the capability to prepare enamel, dentin, caries, cementum and bone in addition to cutting soft tissue.The present study is aimed at evaluating the tensile bond strength a self etching restorative system, on superficial and deep dentin, after cutting the tooth with bur or Er:YAG laser. Methods: Sixty sound extracted human premolars were used in the study. These teeth were then randomly divided into two groups of thirty teeth each. Group 1- Bur cut, cut using diamond cutting disc and Group 2- Laser cut, cut using Er:YAG laser calibrated with 200mJ/10HZ/2.0W under 4ml/min water spray. These were then divided into two more subgroups of fifteen teeth as superficial and deep dentin sub groups. Specimens were coated with bonding agent followed by a microhybrid resin composite (SUREFILL,DENTSPLY). The specimens were then debonded in tension by mounting it on a universal testing machine (Instron Type 4204 Co.USA) and specimen SEM analysis of surfaces was done. Results: Bur cut superficial dentin showed maximum tensile bond strength (22.86 MPa) while bur cut deep dentin showed the least tensile bond strength (15.8MPa),Laser cut superficial dentin and deep dentin showed almost similar bond strength -19.18 MPa and 19.94MPa respectively. Conclusion: The superficial dentin produced better bond strength and results than deep dentin. Surface treatment by Er:YAG laser hampered the adhesion of self etching adhesive systems in both superficial and deep dentin.
ABSTRACT
Restoration of the endodontically treated teeth is complicated by the fact that much or all of the coronal tooth structure has been destroyed by caries, previous restorations and the endodontic access preparation. Post-andcore has been most commonly used when insufficient dentin remains. Methods: Fourty translucent glass fiber post (Tenax fiber Trans Coltene Whaledent) of diameter 1.3 mm and 40 extracted premolars were used. Post were divided into 4 groups of 10 each depending on the pre –treatment of post surface.In Group 1: Multilink N primer A & B was applied on post surface and root dentin for 15 sec, (Control group), group 2 : Monobond S primer was applied for 60 sec, followed by multilink N primer A & B, Group 3: Immersion in 30% H2O2 for 5min, rinsing and application of Monobond S Primer (silane) and multilink N primer A & B and Group 4: application of 25% polyacrylic acid for 5 sec, rinsing, silane and multilink N primer A & B dual cure adhesive. The specimens were then sectioned horizontally into 1- mm-thick post-dentin sections. The post space (9mm) were divided into 3 halves: the coronal, middle and the apical third.The push out bond strength (MPa) were measured using a universal testing machine at a crosshead speed of 0.5mm/sec.Failure mode of each debonded specimen were analyzed using a stereomicroscope. Maximum failure mode were adhesive failure between post and resin cement. Results: The bond strength values were higher in group 3 and group 4 compared to group 2 and group 1. Conclusion: The pre-treatment of fiber post increases bond strength between fiber post and root dentin.
ABSTRACT
Background: It won’t be wrong to admit that composite resins are currently the back bone of aesthetic and conservative dentistry. However a major drawback of composite resins is that their setting reaction involves formation of polymer chains leading to polymerization shrinkage. Aim: To compare microleakage in silorane composite using oblique, vertical and horizontal layering techniques to microleakage of nanofilled composite using oblique, vertical and horizontal layering techniques. Materials and methods: 120 extracted maxillary premolar teeth were assigned to 2 groups based on the material used Group A nanocomposite and Group B-silorane and each group was divided further into 3 subgroups depending on incremental technique used for restoration into horizontal, oblique and vertical (sub groups A1, A2, A3, B1, B2 and B3). A Class 1 cavity measuring 3mm3mm2mm was prepared in all the teeth. In group A teeth Clearfil TMSE Bond (Kurary Medical inc. Okayama, Japan) was applied. Group A teeth were filled with FiltekTM Z350 XT (nanocomposite) (3M ESPE, St Paul, USA) using horizontal (A1), oblique (A2) and vertical (A3) incremental layering technique and each Shafia Sarfi, Neerja Sharma, Ekta Garg, Dildeep Bali. Comparing microleakage in Silorane based composite and nanofilled composite using different layering techniques in class I restorations: An in vitro study. IAIM, 2017; 4(7): 23-32. Page 24 increment was cured for 30 seconds. In Group B teeth P90 system adhesive was applied and teeth were filled with FiltekTM P90 silorane (3M ESPE, St. Paul, USA) using horizontal (B1), oblique (B2) and vertical (B3) incremental layering technique. Specimens were thermocycled for 1000 cycles (5/55ºC, 30 seconds) and immersed in 2% methylene blue dye for 24 hours. Following immersion teeth were sectioned and observed under a stereomicroscope. Results were analysed using KruskalWallis test followed by Mann Whitney U test. Results: Siloranes showed significantaly less microleakage than nanofilled composites. The difference between the horizontal group, oblique group and the vertical group was found to be statistically non-significant (P value >0.05) but mean microleakage was more in vertical group compared to oblique and horizontal group. Conclusion: Within the limitations of this study, we found that Siloranes exhibit significantly less microleakage as compared to nanofilled composites irrespective of the layering technique used.