| Background: The ultimate goal of root canal therapy is to clear the infection,prevent reinfection and promote healing of periapical lesions.Historically,the gutta percha was used to fill the complicated root canal system and blocked the root canal system and the oral cavity,periapical tissue,so as to prevent bacteria and their toxic products into the root canals.Due to the complexity and diversity of the root canal system and the irregular root canal morphology,the gutta percha can only partially adapt to the root canal wall.Simply using the gutta percha creates voids and gaps between it and the root canal wall.Paste can be used to fill the voids?gaps and irregularities,seal the entire root canal system.Preferably a paste material is required to have good sealing ability and insoluble which can increase the success rate of root canal therapy.i Root SP is a calcium silicate-based bioceramic paste material that is insoluble,radiopaque and non-aluminum-containing and has good biocompatibility.It can be used directly for root canal filling without the use of gutta-percha?Purpose:The aim of this study was to evaluate the adapation?bond strength and apical sealing ability of i Root SP when filled with different filling techniques(the cold lateral compaction(CLC)technique / the continuous wave condensation(CWC)technique wit/ Single cone(SC)technology/ Sealer-only backfill(SOB)technology)by using micro-CT?push-out test and leakage experiment.PART ONE:Aim:The aim of this study was to evaluate the adapation of different root canal obturation techniques of i Root SP by micro-CT.Methods: Forty single root maxillary anterior teeth were collected.They were decoronated and trimmed the root length to 12 mm.The root canals were mechanically instrumented with Pro Taper rotary files to F3.The prepared samples were randomly divided into four groups(n = 10)for root canal filling.The canals in four groups were obturated with gutta-percha and(or)i Root SP,by either cold lateral compaction(CLC),continuous wave condensation(CWC),single-core technique(SC)or i Root SP only backfill technique(SOB)respectively.The samples were then placed in a 37 ° C water bath for 7 days to allow completely harden.All samples were scanned with Micro-CT and related software was used to analyze the gap rates between different filling methods,the gap rates for the various filling methods in the same area,and the gap rates for the same method at different sections.Results:(1):The volume of voids and gaps were the lowest with CWC technology(p < 0.05),but there were no significant difference among CLC technology,SC technology and SOB technology(P > 0.05).(2):In the apical third,SOB technique showed the least voids and gaps(P < 0.05),there were no significant difference among other three groups(P > 0.05);in the middle and coronal third,CWC technology showed the least voids and gaps(P < 0.05),while other three groups were not significant(P> 0.05).(3):The volume of voids and gaps in the apical third was significantly less than those in the middle third and the coronal third in CWC technology(P <0.05),but no significantly different in other three groups.PART TWOAim:The aim of this study was to evaluate the bond strength of i Root SP with different root canal obturation techniques.Methods: Forty single root maxillary anterior teeth were collected.They were decoronated and trimmed the root length to 12 mm.The root canals were mechanically instrumented with Pro Taper rotary files to F3.The prepared samples were randomly divided into four groups(n = 10)for root canal filling.The canals in four groups were obturated with gutta-percha and(or)i Root SP,by either cold lateral compaction(CLC),continuous wave condensation(CWC),single-core technique(SC)or i Root SP only backfill technique(SOB)respectively.The samples were then placed in a 37 ° C water bath for 7 days to allow completely harden.All samples were sliced perpendicularly to the long axis from the apical to the coronal side on a low-speed microtome to a thickness of 1.00 ± 0.2 mm(1-9).The first 3 pieces represent the apical 1/3 segment,the middle 3 pieces represent the middle 1/3 segment,and the last 3 pieces represent the coronal 1/3 segment.A sample was randomly selected from each segment as an experimental sample and placed on a universal testing machine,record the load when the filling material is loose,calculate the bond strength and observe the fracture mode.Results:(1):In the apical third,the SOB technology had the lowest bond strength,and there were a significant difference with the CLC technology and CWC technology(P <0.05).(2):In the coronal third,CWC technology showed the lowest bond strength,(P < 0.05).There were a significant difference between the CLC technology and SC technology(P <0.05)while other groups were not significant(P > 0.05).(3): There was a statistically significant difference among three segments in CWC technology group(P<0.05).In SC technology group,the bond strength in the coronal third was lower than those in the middle third and the apical third(P<0.05).There were no significant difference among three segments in CLC technology group and SOB technology group respectively.(4)The mainly fracture mode was interfacial fractures in CWC group while cohesive fracture and mixed fracture in other three groups.PART THREEAim:The aim of this study was to evaluate apical sealing ability of i Root SP with different root canal obturation techniques.Methods: Thirty-six single root mandibular premolar were collected.The root canals were mechanically instrumented with Pro Taper rotary files to F3.The prepared samples were randomly divided into four experimental groups(n = 8)for root canal filling.The remaining four teeth were classified as a negative group(n=2)and apositive control group(n=2)respectively.The canals in four experimental groups were obturated with gutta-percha and(or)i Root SP,by either cold lateral compaction(CLC),continuous wave condensation(CWC),single-core technique(SC)or i Root SP only backfill technique(SOB)respectively.The samples were then placed in a 37 ° C water bath for 7 days to allow completely harden.All samples of experimental groups were sealed with nail polish except 1 mm from the apex and negative control group was fully enclosed while positive control group was fully open,then all root tips were immersed in 0.1% methylene blue solution for 7 days,then cut along the long axis of the tooth on a low-speed microtome,observed under a microscope(X10)and photographed.The software of image J was used to measure the apical leakage.Results: Apical microleakage was present in all filling techniques,but the difference was not statistically significant(P>0.05).Conclusions: 1: All filling techniques will produce voids and gaps.CWC technology shows the best filling quality and root adapation;SOB technology has the similar performance as CLC technology and SC techmology.2: Filling techniques affect the bond strength of the i Root SP to the root canal wall.3: All filling techniques can not completely seal the root apical,SOB technology has the similar apical sealing performance as other techniques. |
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