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: Cleaning and shaping the root canal is an important phase in endodontic therapy. A prepared root canal should have a shape that flares from apical to coronal regions, maintaining the apical foramen and not changing the original canal curvature. Aim: To compare canal transportation, canal centring ability and remaining dentin thickness, in curved root canals using Twisted Files, PathFiles-ProTaper System, RaCe files, WaveOne reciprocating files and hand NiTi K-files with Cone Beam Computed Tomography. Materials and methods: 125 canals with completely formed apices and angle of curvatures ranging from 10 degrees to 60 degrees were used. The teeth were divided in five experimental groups of 25 each. Instrumentation was performed in Group I with Twisted files, Group II with PathFile-ProTaper, Group III with Hand NiTi files, Group IV with RaCe files and Group V with WaveOne reciprocating files. CBCT images were obtained before and after instrumentation with Kodak CS9300 equipment Neerja Sharma, Shafia Sarfi, Avdesh Sharma, Mandeep S Grewal. Evaluation of canal preparation with rotary and hand Niti files in curved root canals using Cone Beam Computed Tomography: An In Vitro Study. IAIM, 2017; 4(7): 45-55. Page 46 (CS3D Imaging Software 3.1.9). The amount of canal transportation, centering ability and remaining dentin thickness was calculated at nine levels. Results were analysed using ANOVA test and Post-hoc Bonferroni Multiple Comparison test. Results: Statistically significant difference was noted among the groups at the middle and apical third level with WaveOne files showing the least and hand NiTi files showing the highest transportation. The mean centering ratio was statistically highest with WaveOne and smallest with hand NiTi files at the middle third level. At the apical level (p < 0.05) the mean remaining dentin thickness was highest with WaveOne and smallest with PathFile-ProTaper. Conclusion: WaveOne and Twisted files were similar in terms of canal transportation, centring ability and remaining dentin thickness. Hand NiTi files and Pathfile-ProTaper systems produced maximum amount of canal aberrations.