Three-dimensional Analysis Of Root Canal Morphology Of Mandibular First Premolar In Different Ages

Objectives:Microorganisms are the main causes of pulpal and periapical diseases.Root canal therapy(RCT)is one of basical treatment methods.Thorough knowledge of the root canal system,especially of age-related changes,is a key factor for the root canal therapy.Before,Micro CT(MCT)was mainly applied to observe and analyze the root canal morphology,and further the taper of the canal.Such information is valuable for clinic practice.provide reference for dental treatment and repair in clinic.However,it is rarely reported about the difference of volume and area of canal of the mandibular first premolar in different physiological conditions.The aim of this study is to compare the number of lateral root canals and apical ramifications,the morphology of canal of the young people with the old ones,and to provide reference for dental treatment.Material and methods:The mandibular first premolars of younger group,being extracted for orthodontic treatment and that of older group,being pulled out because of loose were selected.All the specimen were reserved after debriding periodontal tissue and Calculus.Then,ten mandibular first premolar with one canal from each group were selected and scanned by Micro-CT and then inserted the scanning data into the computer software.CTAn software was applied to reconstruct three-dimensional image and calculate the volume of root,the volume of canal,area of canal,and the SMI.After that,these data was performed by t-test,using SPSS Statistics 17.0 software and compared between two groups.Results:1,The incidence rate of lateral root canal and apical ramification in two younger group was 80%,compared with elder group 60%.The number of lateral root canal and apical ramification was so different,with1.3 and 0.5 per tooth respectively(P<0.05).2,The volumes of roots of two groups had no difference,132.96mm~3and 136.27mm~3 respectively(P=0.487).3,The average internal volume of canal in younger group,12.31 mm~3,was much higher than that in elder group,3.80mm~3(P<0.05).4,The average volume fraction of cervical,middle,and apical third of these root canals:Teeth of young people were:0.59,0.32,0.09 respectively.And teeth of elder people were:0.59,0.29,0.12 respectively.The average volume fraction of middle and apical third of root canals in these two groups had obvious differences(P<0.05).5,Surface area of canal of younger group was 48.45 mm~2,almost two times that of elder group,which was 25.76 mm~2(P<0.05).6,The SMI value in elder group was bigger and had significant differences as compared with that of younger group(P<0.05).Conclusions:In this study,we found that the volume of canal decrease as people grow older.The shape of canal became more and more regular with age-related changes and calculations of canal.If people had periodontitis,calculations usually happened in the middle and apical third of canal,which caused the number of lateral root canal and apical ramification in elder group decreased.The canal cross-sections of young people were most oval or dumbbell-shaped,ever if the volume of which was big,so it was difficulty to clean the whole canal.In conclusion,we need to throughly understand the different characteristics of root canal at different ages,as well as pay more attentions to root canal preparation and disinfection in order to prove the success rate of RCT.