Comparison Of Penetration And Obturation Density Using Nickel-titanium And Stainless Steel Finger Spreader In Curved Canals

Lateral condensation of cold gutta-percha is widely used throughout the world to fill root canals . The finger spreaders are the instruments which can be used to condense the gutta-percha points. SS spreaders are still used during obturation .Due to their stiffness, stainless steel spreaders may fail to achieve within 1.0mm of working length in curved canals. The greater penetration of NiTi spreaders in cured canals is due to their greater flexibility, which would allow them to follow the curvature of the canal.The purpose of this study was to compare nickel-titanium and stainless-steel spreader penetration in curved canals and plastic blocks, to compare the initial penetration depth of nickel-titanium and stainless steel spreaders during lateral compaction of .02 or .04 tapered master gutta-percha cones and to evaluate the quality of obturation.PART Ⅰ Comparison of NiTi and stainless-steel spreaders penetration in curved canalsAim: To compare nickel-titanium (NiTi) and stainless-steel (SS) spreaders penetration in curved canals.Method: Twenty prepare plastic blocks with a 35°curvature were used for the study. The forces required to inset spreaders to within 1mm of working length in emptycanals and within 3mm of working length in canals containing a master cone were measured. The depths of penetration of spreaders with a master cone in place using 15N force were measured.Result: NiTi spreaders required significantly less force than SS spreaders (2.72N vs 7.48N; P<0.01) in empty canals, as well as in canals containing a master cone (38.3N vs 48.7N; P<0.01). NiTi spreaders penetrated significantly deeper than SS spreaders (13mm vs 12mmm; P<0.01) when using the same force.PART II Comparison of Nickel-Titanium and Stainless-steel Spreader Penetration of .04 and .02 Taper Gutta-perchaAIM: To compare the initial penetration depth of nickel-titanium (NiTi) and stainless-steel(SS) spreader during lateral compaction of .04 and .02 tapered master gutta-percha cones.Method: Thirty-eight extracted mandibular premolars with a single canal were divided into two experimental groups by degree of curvature for comparison. Four groups of measurements were obtained within each canal. The groups consisted of: (a) NiTi spreader with size 40/.02 taper master cone; (b) NiTi spreader with size 40/.04 taper master cone; (c) SS spreader with size 40/.02 taper master cone; (d) SS spreader with size 40/.04 taper master cone.Result: NiTi spreaders penetrated to a significantly greater depth than SS spreaders (0.48mm vs 1.43mm ) using .02 tapered gutta-percha in canal curvatures greater than 20 degrees and when using .04 tapered gutta-percha regardless of 0 to 20 degrees (1.95mm vs 2.79mm). No significant difference occurred between NiTi and SS spreader penetration using .02 tapered gutta-percha in canal curvatures of 0 to 20 degrees (p>0.05).PART HI Comparison of Laterally Condensed .04 and .02 TaperedGutta-Percha in VitroAIM: To compare the quality of the seal in canals prepared in a standardized manned and obturated with a .04 or a .02 tapered gutta-percha master cone using lateral condensation.Method: Eighty extracted mandibular premolars with a single canal were divided into two experimental groups by degree of curvature for comparison. The Canals were instrumented by NiTi ProFile and obturated with cold laterally condensed gutta-percha. Horizontal sections were cut 2 and 4mm from the apex. The area of the canal and gutta-percha in cross-sections was measured using an image analysis programme.Result: In canal curvatures greater than 20 degrees the levels of 2mm have significantly more gutta-percha fill with .02 tapered gutta-percha using NiTi spreaders. In canal curvatures of 0 to 20 degrees the levels of 2mm have significantly more gutta-percha fill with .04 tapered gutta-percha compared with .02 tapered gutta-percha between NiTi and SS spreaders. No significant difference occurred using .02 tapered gutta-percha (p>0.05). At 4mm level there was no significant difference between .04 and .02 tapered gutta-percha (p>0.05).Conclusion: The NiTi spreaders penetrated to a significantly greater depth and required significantly less force than SS spreaders in cured canals .The area occupied by gutta-percha was significant greater for filling with .04 tapered gutta-percha compared with .02 tapered gutta-percha.