Study Of Root Canal Morphology Of Mandibular Incisors By Using Micro-computed Tomography In Vitro

AIMThe aim of this study was to obtain a three-dimensional analysis of the rootcanal morphology of mandibular incisors using high-resolution micro-computedtomography (μ-CT) scanning and three-dimensional reconstruction in vitro.METHODS1.62extracted mandibular incisors were selected. The teeth were scanned by theμ-CT and the root canal morphology was categorized according to Vertuccis’classification.2. The location and the morphology of the major foramens were recorded,andthe distance from the anatomical root apex to the apical foramen and the diameter ofthe foramen were measured.3. Choose mandibular incisors with single root and root canal curvature not morethan20°,30specimens were obtained.each root canal was divided into3-apical1/3,middle third1/3and cervical1/3,The mesio-distal and the bucco-lingual diameterscorresponding to each section in the upper and lower root canal cross-section weremeasured, then calculated the three corresponding root canal tapers.4.The data obtained was analysed using the SPSS17.0statistical software.RESULTS1.Based on the Vertucci root canal classification, the62mandibular incisorswere divided as following:83.9%(52/62) were identified as TypeⅠ (1-1),3.2%(2/62)TypeⅡ(2-1)，11.3%(7/62) Type Ⅲ (1-2-1),1.6%(1/62) Type Ⅴ (1-2);2.The foramen was at the tip of the root in43.5%％of teeth；The apicalforamen shape of mandibular incisors can be divided into three types: circular(14.5%), oval (72.6%) and flat (12.9%)；The longest diameter of the major apicalforamen was （0.4538±0.13206） mm and the shortest diameter was（0.3242±0.07785）；The mean distance from the root apex to the major lateral apicalforamen was （0.6126±0.29760）mm;3.The bucco-lingual diameters are greater than the mesio-distal diameters; Start from the CM cross-section, the more near the tip, the smaller the gap between the twotracks, means that the root canal’s cross section tend to become more circular. Theroot canal tapers in bucco-lingually are greater than the mesio-distal’s. The averagetaper of cervical, middle and apical third were-0.07，0.20，0.12bucco-lingually and0.08，0.05，0.01mesio-distally.There were significant differences (P <0.05) betweenthe bucco-lingual tapers of three sections as well the mesio-distal ones.CONCLUSIONS1.In the present study，the majority of mandibular incisors had a single canal(83.9%of teeth possessed a Type I canal system). Although16.1%of the rootspossessed two Canals.lateral canals were observed only in4.8%of teeth,and theincidence of apical ramifications was19.4%.2.Less than half of the mandibular incisors (43.5%) had centrally locatedforamina,which should be taken into account in clinic when read the root fillingRadiograph.3.The main shape of the major apical foramen was oval,the application of warmgutta should be considered in the clinical to improve the efficiency of seal.4.Most of the Root canal cross-section in mandibular incisors arenon-circular,the application of SAF can prove the efficiency of cleaning and shapingof root canals and reduce the risk of Root fracture as well.5. As the bucco-lingual diameter of root canals were greater than themesio-distaldiameter, and the bucco-lingual taper was also far greater than mesio-distal taper inthe middle and apical third of root. he mesio-distal diameter and taper should be takeas the reference for instrument choice in root canal therapy.