Shanghai Journal of Stomatology

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Shanghai Journal of Stomatology 2009, 18 (6): 604-608.

Abstract （105）

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Accuracy of tooth segmentation algorithm based on deep learning

ZHANG Bo-jun, CUI Zhi-ming, LIU Zhi-xu, CHEN Si-yue, GU Kai-jun, LI Si-tong, WU Yan-qi, SHEN Ding-gang, ZHU Min

Shanghai Journal of Stomatology 2024, 33 (4): 339-344. DOI: 10.19439/j.sjos.2024.04.002

Abstract （118）

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PURPOSE: The established automatic AI tooth segmentation algorithm was used to achieve rapid and automatic tooth segmentation from CBCT images. The three-dimensional data obtained by oral scanning of real isolated teeth were used as the gold standard to verify the accuracy of the algorithm. METHODS: Thirty sets of CBCT data and corresponding 59 isolated teeth were collected from Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. The three-dimensional tooth data in CBCT images were segmented by the algorithm. The digital information obtained by scanning the extracted teeth after processing was used as the gold standard. In order to compare the difference between the segmentation results and the scanning results of the algorithm. The Dice coefficient(Dice), sensitivity (Sen) and average symmetric surface distance (ASSD) were selected to evaluate the segmentation accuracy of the algorithm. The intra-class correlation coefficient(ICC) was used to evaluate the differences in length, area, and volume between the single tooth obtained by the AI system and the digital isolated tooth. Due to the existence of CBCT with different resolution, ANOVA was used to analyze the differences between groups with different resolution, and SNK method was used to compare them between two groups. SPSS 25.0 software package was used to analyze the data. RESULTS: After comparing the segmentation results with the in vitro dental scanning results, the average Dice value was (94.7±1.88)%, the average Sen was (95.8±2.02)%, and the average ASSD was (0.49±0.12) mm. By comparing the length, area and volume of a single tooth obtained by the digital isolated tooth and the AI system, the ICC values of the intra-group correlation coefficients were 0.734, 0.719 and 0.885, respectively. The single tooth divided by the AI system has a good consistency with the digital model in evaluating the length, area and volume, but the segmentation results were still different from the real situation in terms of specific values. The smaller the voxel of CBCT, the higher the resolution, the better the segmentation results. CONCLUSIONS: The CBCT tooth segmentation algorithm established in this study can accurately achieve the tooth segmentation of the whole dentition in CBCT at all resolutions. The improvement of CBCT resolution ratio can make the algorithm more accurate. Compared with the current segmentation algorithms, our algorithm has better performance. Compared with the real situation, there are still some differences, and the algorithm needs to be further improved and verified.

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Comparison of the effects of using iRoot BP plus and MTA apical barrier surgery in young permanent teeth with chronic apical periodontitis

SUN Yan-ni, ZHAO Lei, LIU Wei, YIN Xiao-ping

Shanghai Journal of Stomatology 2024, 33 (3): 260-264. DOI: 10.19439/j.sjos.2024.03.008

Abstract （123）

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PURPOSE: To explore the effect of using iRoot BP plus and MTA apical barrier surgery in young permanent teeth with chronic apical periodontitis. METHODS: A total of 122 patients with chronic periapical periodontitis with open root tips of permanent teeth were randomly divided into experimental group (n=61, 61 teeth) and a control group (n=61, 61 teeth). Patients in the experimental group received iRoot BP plus plus apical barrier surgery, while those in the control group received MTA apical barrier surgery. The old periapical index (O-PAI), apical transmission area, efficacy, treatment times, and inflammatory factor levels of the two groups of patients were compared at 3, 6, 9, and 12 months after surgery. SPSS 19.0 software package was used for statistical analysis. RESULTS: At 12 months after surgery, the O-PAI ratings of the experimental group and the control group were (1.48±0.36) and (1.71±0.42), respectively, and the apical transmission area was (0.51± 0.14) and (1.09±0.31). There was a significant difference in the O-PAI ratings and apical transmission area between the two groups(P<0.05). At 3 months, 6 months, and 12 months after surgery, the O-PAI scores of patients in both groups gradually decreased (P<0.05). After 12 months of treatment, the success rates of the experimental group and the control group were 98.36% and 88.52%, respectively, with significant difference between the two groups (P<0.05). The treatment frequency of patients in the experimental group and the control group was (3.64±0.58) times and (4.72±0.61) times, respectively, with a significant difference between the two groups(P<0.05). After 3 months of treatment, the serum hs-CRP levels in the experimental group and the control group were (6.89±1.13) mg/L and (7.25±1.40) mg/L, respectively, with a significant difference compared to pre-treatment(P<0.05). After 3 months of treatment, the serum IL-6 levels in the experimental group and the control group were (82.04±19.62) mg/L and (87.52±20.85) mg/L, respectively, with significant differences compared to pre-treatment (P<0.05). There was no significant difference in serum IL-6 and hs-CRP levels between the two groups before and after treatment(P>0.05). CONCLUSIONS: iRoot BP plus apical barrier surgery for the treatment of chronic apical periodontitis with open permanent teeth can reduce the O-PAI index, decrease the number of postoperative visits, and have a higher postoperative success rate.

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Analysis of three dimensional stability of the hypoplastic maxilla after orthognathic surgery in cleft lip and palate patients

YINGWANG Jun-zi, SHEN Shun-yao, LI Biao, SUN Hao, ZHANG Tian-jia, WANG Xu-dong

Shanghai Journal of Stomatology 2016, 25 (3): 345-351.

Abstract （370）

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PURPOSE: To establish a three dimensional spacial measurement method to analyze the short-term stability of maxilla after orthognathic surgery in cleft lip and palate patients. METHODS: Twenty-five patients with maxillary hypoplasia secondary to cleft lip and palate seeking for orthognathic surgery were included in this study between January 2008 and September 2012. The spiral CT scan for the skull were taken 6 weeks preoperatively (T0), 4 days postoperatively (T1),3 months postoperatively (T2), and 6 months postoperatively (T3) and collected. A three dimensional analytic method for measuring maxilla was set up in ProPlan CMF software, and good repeatability of identification of landmarks was confirmed. Twenty-two indicators to describe the maxillary position and three new angles to describe the maxillary orientation were measured and analyzed. Student's t test was used to analyze the difference between T2 and T3 using SPSS 16.0 software package. RESULTS: In 25 patients with cleft palate there was a translational relapse upwards along vertical axis and a pitch-up relapse of maxilla with an average of 7.46% at the anterior part of the cleft maxilla. The relapse rate was 30.95% in LUCLP, 8.01% in RUCLP, and 34.76% in BCLP, but with no significant difference. Along the horizontal axis, there was a maxillary translational relapse toward noncleft side in both LUCLP and RUCLP group, while a yaw relapse was confirmed with the anterior part of maxilla toward noncleft side and the posterior part toward cleft side. CONCLUSIONS: There is a three-dimensional relapse tendency for the maxilla in the cleft patient postoperatively. The established three-dimensional analytic method well describes the special position of cleft maxilla especially in the translational and rotational movement of maxilla in three different axes comparing with that from lateral cephalometry, thus providing references for accurate measurements in study of the three dimensional maxillary stability after orthognathic surgery.

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Repair of mandibular defects with hydrogel loaded with nano-hydroxyapatite in rats

XU Lai-jun, YUAN He, YE Qing, LI Ji-yao

Shanghai Journal of Stomatology 2022, 31 (5): 449-453. DOI: 10.19439/j.sjos.2022.05.001

Abstract （325）

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PURPOSE: To observe the effect of gellan gum loaded with nano-hydroxyapatite (GG/nHA) on repairing mandibular defect in rats. METHODS: Critical bone defects with 5 mm in diameter on the mandible of 16 SD rats were created and randomly divided into two groups. The bone defects in the experimental group were injected with GG/nHA and the control group were filled with absorbable gelatin sponge. The rats were sacrificed at 4 and 8 weeks after operation. The bone tissue healing was evaluated by Micro-CT. Bone tissue repairing effect was evaluated by hematoxylin-eosin (H-E) staining and Masson staining. GraphPad Prism 8.0 software package was used for statistical analysis. RESULTS: The prepared GG/nHA had a good injectability and could be delivered to the bone defect area with a syringe. Four and 8 weeks after operation, the newly formed bone and bone volume fraction (BV/TV) in the experimental group were higher than those in the control group, and the difference was statistically significant (P<0.05). Larger number of new bone were observed in the experimental group than the control group by H-E staining and Masson staining. CONCLUSIONS: GG/nHA can be injected into the mandibular defect area to promote its healing, and it is expected to be used as a novel bio-material for minimally invasive repair of oral and maxillofacial bone defects.

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The effect of Frankel Ⅲ orthodontic appliance combined with lip muscle training in the treatment of malocclusion during mixed dentition

DING Min-lin, ZHANG Hai-liang, ZHANG Ji-min

Shanghai Journal of Stomatology 2024, 33 (4): 432-437. DOI: 10.19439/j.sjos.2024.04.018

Abstract （65）

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PURPOSE: To exploring the clinical effect of lip muscle training combined with Frankel Ⅲ orthodontic appliances in correcting Class Ⅲ malocclusion during the mixed dentition period. METHODS: One hundred children with Class Ⅲ malocclusion during the mixed dentition period admitted to Hangzhou Greentown Stomatological Hospital from June 2018 to December 2022 were selected. The children were randomly divided into a combination group (treated with lip muscle training and Frankel Ⅲ orthodontic appliance) and a control group (treated with Frankel Ⅲ orthodontic appliance), with 50 cases in each group. X-ray cephalometric indicators, temporomandibular joint parameters, upper airway measurement parameters and 12 month follow-up of the two groups of children were compared before and after treatment. SPSS 21.0 software package was used for statistical analysis. RESULTS: Before treatment, there was no significant difference of SNA, SNB, ANB, U1-NA, L1-NB, ANS-Ptm, S-Ptm, Co Po, Co-S, MP-SN, MP-FH and NP-FH between the combination group and the control group (P>0.05). After treatment, ANB, U1-NA, L1-NB and MP-SN in the combination group were significantly higher than those in the control group, while NP-FH were significantly lower than that in the control group(P<0.05). Before treatment, there was no significant difference of the joint space, anterior joint space and posterior joint space between the combination group and the control group patients(P>0.05); after treatment, the joint space and the joint space in the combination group were significantly higher than those in the control group(P<0.05). Before treatment, there was no significant difference of Ba PNS, Ad1 PNS, Ad2 PNS, Mc1 Mc2, SPP-SPPW, U-MPW, PAS and V-LPW between the combination group and the control group(P>0.05); after treatment, Ad2-PNS in the combination group was significantly higher than that in the control group(P<0.05). After 12 months of follow-up, the recurrence rate of the combination group was 2.00%, which was significantly lower than that (16.00%) of the control group (P<0.05). CONCLUSIONS: The combination of lip muscle training and Frankel III orthodontic appliances is more conducive to correcting Class III malocclusion during the replacement period, improving upper airway morphology, and reducing the recurrence rate after treatment.

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Effects of morphology of the microgroove titanium surface on expression of vinculin in human gingival fibroblasts

LAI Ying-zhen,CHEN Jiang,LIN Shan

Shanghai Journal of Stomatology 2015, 24 (2): 182-187.

Abstract （216）

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PURPOSE: To investigate the effects of morphology of the microgroove surface on the expression of vinculin in human gingival fibroblasts, with the hope of providing basis for size selection of microgroove for transmucosal part of dental implants. METHODS: Microgroove titanium surfaces were fabricated by photolithography with parallel grooves: 15 μm, 30 μm or 60 μm in width and 5 μm or 10 μm in depth. The groups that used different microgroove surfaces were denoted as T15/5, T15/10, T30/5, T30/10, T60/5, and T60/10. Smooth titanium surfaces (T0) were used as controls. Surface topography was detected. HGFs were cultured on the microgroove surfaces. Morphology of vinculin was analyzed using CLSM. Expression level of vinculin was compared among different groups by real-time PCR and Western blotting. SPSS17.0 software package was used for statistical analysis. RESTULTS: Immunofluorescence staining revealed increase of green vinculin fluorescent spots as the increase of microgroove width, while T60 group had the highest mRNA and protein expression and T15 group had the lowest. Microgroove depth had no effect on the expression of vinculin under the same width. CONCLUSIONS: Morphology of microgroove surface has effect on the expression of vinculin, and the morphology of microgroove surface in T60 group is the best size for the transmucosal part in terms of expression of vinculin protein expression.

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Experts consensus on diagnostic and therapeutic strategies for malocclusions at early developing stage

FANG Bing, JIN Zuo-lin, BAI Yu-xing, WANG Lin, ZHAO Zhi-he, LI Wei-ran, BAI Ding, HE Hong, LIU Yue-hua, HU Min, SONG Jin-lin, CHEN Li-li, CAO Yang, WU Ting-xi, LI Song, LI Huang, SHI Jie-jun, CHU Feng-ting

Shanghai Journal of Stomatology 2021, 30 (5): 449-455. DOI: 10.19439/j.sjos.2021.05.001

Abstract （852）

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Early orthodontic intervention remains a controversial notion in current dental care regime. Whilst early orthodontic treatment for children is the province for orthodontic specialists, a growing number of general practitioners, who may not possess sufficient specialty knowledge, are also involved, raising the concerns about the propriety and quality of their treatment modalities. However, orofacial development of children and adolescents is in a very complicated environment. Comprehensive theoretical knowledge and a great wealth of practical experience are required to ensure the final treatment effect. The possible complications should be kept under control and fully informed to patients and their parents. In order to unify and standardize early orthodontic treatment protocol and help to promote healthy and orderly development of early orthodontic treatment, this consensus summarized the practical experience of orthodontic experts from many famous colleges and affiliated hospitals for clinical reference.

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A correlation study between the occlusal cant and temporomandibular joint space in patients with mandibular lateral deviation

LI Shuang, XIAO Rong-rong, WANG Ming-feng

Shanghai Journal of Stomatology 2024, 33 (3): 318-323. DOI: 10.19439/j.sjos.2024.03.019

Abstract （122）

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PURPOSE: To investigate the correlation between the occlusal canting and the bilateral temporomandibular joint (TMJ) space in adult and juvenile mandibular deviation patients and study the mutual influence between the occlusal canting and mandibular position, in order to provide references for clinical treatment. METHODS: CBCT data of mandibular deviation patients（20 adults,20 juveniles）were selected. Inivo5 Dental Anatomage software was used to reconstruct the structures. The occlusal cant and vertical height of the bilateral maxillary from canines to first molars were measured, and the vertical heights difference between the same teeth on both sides was calculated. The anterior, superior and posterior space of temporomandibular joint were measured respectively in both groups. Pearson correlation analysis between the occlusal canting and bilateral condylar space was carried out by using SPSS 17.0 software package. RESULTS: In the juvenile group, negative correlations were found between the occlusal cant and the superior TMJ space on the deviated side (P<0.05). Negative correlation was found between the vertical height difference of bilateral canines and the anterior TMJ space on the deviated side in the juvenile group(P<0.05). In the adult group, no significant correlation was observed among those correlated examination (P>0.05). CONCLUSONS: The occlusal canting is moderately correlated with mandibular position in the early stage of mandibular deviation patients. Early treatment of mandibular deviation is of great importance in preventing its progression into severe skeletal malocclusion, and more attention should be paid on the correction of the canted frontal occlusion plane.

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A retrospective study on incisor root resorption in patients treated with bracketless invisible appliance and straight wire appliance

WANG Guan, YANG Lu, ZHANG Yu-feng, LUO San-lian, ZHENG Ji-wei

Shanghai Journal of Stomatology 2017, 26 (1): 121-124. DOI: 10.19439/j.sjos.2017.01.027

Abstract （436）

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PURPOSE: To assess root resorptions in patients treated with bracketless invisible appliance and straight wire appliance using cone-beam CT (CBCT). METHODS: Twenty-eight patients treated with bracketless invisible appliance (as experimental group) or straight wire appliance (as control group) were randomly selected. CBCT images were analyzed at 3 time points (pre-operation, 6 month after operation, post-operation). Root resorption was calculated using root length at 3 time points. The difference between the 2 groups was analyzed with SPSS16.0 software package. To those teeth with no root length reduction, the bone defect was evaluated using CBCT. RESULTS: After 6-month of treatment, 47.3% teeth from the experimental group had root resorption, while 68.3% in the control group. There was significant difference between the 2 groups (P<0.05). Root absorption of maxillary central incisors from the 2 groups was more severe than other teeth (55% in the experimental group, and 75% in the control group). After orthodontic treatment, the incidence of root resorption in the control groups increased to be 85.3% and 68.3% in the experimental group (P<0.05). To those teeth with no root resorption, bone defect was more common in the palatal side (18% in the experimental group, 14% in the control group). CONCLUSIONS: Compared with straight wire appliance, patients using bracketless invisible appliance suffer from less root resorption.

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Effect of children's oral health cognition and behavior on oral health status

LI Li, JIN Hao, SHENG Kai, JI Ping-ping, DING Qin, HOU Li-li

Shanghai Journal of Stomatology 2021, 30 (4): 406-409. DOI: 10.19439/j.sjos.2021.04.013

Abstract （295）

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PURPOSE: To investigate the current status of oral health cognition behavior and oral health status of children, and to provide countermeasures for the prevention and treatment of oral diseases in children. METHODS: A total of 387 primary school students in the urban area of Shanghai from December 2018 to February 2019 were surveyed using Children's Oral Health Questionnaire and child oral health impact profile（COHIP）. SPSS 24.0 software package was used to conduct statistical analysis of the results through descriptive, univariate and multivariate analysis. RESULTS: The cognition of oral health of children aged 6-9 years old in Shanghai urban area was generally good, but their oral health behavior was average. The caries rate of 387 children reached 57.4%, and the oral health status was not good. Correlation analysis and regression analysis showed that children's oral health behavior was positively correlated with oral health cognition（r=0.260,P<0.05）, and negatively correlated with positive and negative effects of oral health status（r=-0.333,-0.181,P<0.05）, while children's oral health cognition had no significant effect on their oral health status（P>0.05）. CONCLUSIONS: The better the oral health behavior habits of children, the greater the positive impact on oral health status; the development of oral health education for children requires more attention to the cultivation of oral health behavior patterns.

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Study of the mucosal morphological difference of distal-extension of mandibular dentition defect impressions taken by intra-oral digital scanning and selective pressure impression technique

GONG Zhi-cheng, PENG Yan, ZHONG Qun, WU Xue-ying, FANG Shuo-bo

Shanghai Journal of Stomatology 2024, 33 (3): 306-311. DOI: 10.19439/j.sjos.2024.03.017

Abstract （97）

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PURPOSE: To compare the mucosal morphological difference in distal-extension area of mandibular dentition defect taken by intra-oral digital scanning and selective pressure impression techniques. METHODS: Seventeen patients with Kennedy Class I and Class II dentition defect in lower jaw were included, including twenty-two distal-extensions. Intraoral digital scanning and functional impression technique were taken in each patients, respectively. Laboratory cast scanner was used to scan the plaster casts made from the selective pressure impression to obtain the three-dimensional data. All the data were stored in STL format. The 3D data collecting from intra-oral digital scanning and selective pressure impression from the same patient were compared by Geomagic Control 2014 software. Root mean square of 2.5mm diameter area was calculated in 5,10,15 mm from terminal tooth. Pearson's correlation test was used to analyze the correlation of the distance and morphological difference with SPSS 20.0 software package. RESULTS: Mean mucosal morphological difference of jaw distal-extension edentulous area taken by intra-oral digital scanning and selective pressure impression techniques was (0.37±0.12) mm. There was positive correlation between distance from terminal tooth and mucosal morphological difference(P<0.05). Morphological differences in 5, 10, 15 mm from terminal tooth were (0.14±0.11) mm, (0.22±0.13) mm and (0.39±0.16) mm, respectively. CONCLUSIONS: In this study, there was positive correlation between the length of distal-extension edentulous area and mucosal morphological difference, while the kind of ridge defect and mucosal thickness may also affect the morphological difference quantity.

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Analysis of polyetheretherketone framework on the stress distribution of implant-supported fixed maxillary prosthesis: 3-D finite element analysis

HAN Xiang-yong, JU Ya-qiong, ZHANG Lin-lin, TIAN Zhi-juan

Shanghai Journal of Stomatology 2024, 33 (4): 367-372. DOI: 10.19439/j.sjos.2024.04.006

Abstract （79）

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PURPOSE: To analyze the stress distribution of polyetheretherketone framework of implant-supported fixed maxillary prosthesis by three-dimensional finite element method. METHODS: Three dimensional finite element model of implant-supported fixed maxillary prosthesis was established. Polyetheretherketone as framework material, resin, zirconia, PEEK, baked plastic and lithium silicate were used to make crown prosthesis as experimental group, pure titanium and monolithic zirconia prosthesis model was used as control group. The feasibility of PEEK framework was analyzed by loading 150N axially and obliquely on the first molar, and the maximum compressive stress, minimum tensile stress and von Mises principal stress of the framework, crown, screw, implant, cortical and cancellous bone were measured and compared. RESULTS: Under axially loading, the von Mises stress in the monolithic zirconia and lithium silicate crowns were 361 MPa and 295 MPa, while the stress in resin and PEEK crowns were 35 MPa and 37 MPa, respectively. The screw von Mises stress of the experimental group was 694-724 MPa, which was much higher than 61 MPa of the control group.The maximum and minimum stresses of the screw appeared in the resin crown and PEEK crown group. Under oblique loading,von Mises stress of the framework in the experimental group was lower than that in the control group, but the maximum stress appeared in the resin crown and PEEK crown. von Mises stresses of monolic zirconia and lithium disilicate crowns in the experimental group were higher than that of resin and PEEK crowns. von Mises stress of the implant in the experimental group was twice that of the control group. von Mises stress in screw of the experimental group was much higher than that of the control group, and the maximum stress was 22 times that of the control group. The stresses of cancellous bone and cortical bone in the experimental group were twice that of the control group, and the differences were larger than that under vertical loading. CONCLUSIONS: In order to reduce the stress of crowns,resin or PEEK materials are preferred to be used as the crown prosthesis when PEEK was framework of implant-supported fixed maxillary prosthesis. Reducing the cantilever and lateral force may avoid excessive stress in screw.

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Application of PDCA theory in prosthodontic for standardized training of dental residents

JIA Shuang, WANG Jue, ZHONG Qun, CHEN Li, LU Han

Shanghai Journal of Stomatology 2024, 33 (4): 438-442. DOI: 10.19439/j.sjos.2024.04.019

Abstract （60）

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PURPOSE: To evaluate the application effect of PDCA cycle teaching mode in the standardized training and teaching of dental residents in prosthodontics speciality. METHODS: A total of 46 dental residents in Shanghai Stomatological Hospital from 2020 to 2022 were selected as the research subjects, and divided into experimental group (n=23) and control group(n=23), the control group adopted conventional teaching method, while the experimental group adopted PDCA cycle teaching method on the basis of the control group. The theoretical assessment, clinical operation assessment and satisfaction of the teaching effect of the two groups of residents were compared with SPSS 20.0 software package. RESULTS: The theoretical assessment, clinical operation assessment and satisfaction of the residents in the experimental group were all higher than the data obtained in the control group, and the difference was statistically significant(P<0.05). CONCLUSIONS: Compared with the traditional model teaching group, PDCA cycle teaching model can train the dental residents more personalized, better improve the clinical comprehensive quality and professional level, and achieve good feedback effect.

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Study of the effect of different methods on the removal of calcium hydroxide in root canal by micro-computed tomography in vivo

WU Tian-tian, Han Yan-yan, WANG Yi

Shanghai Journal of Stomatology 2024, 33 (3): 225-228. DOI: 10.19439/j.sjos.2024.03.001

Abstract （150）

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PURPOSE: To establish molar root canal model with micro-computed tomography (Micro-CT) and evaluate the removal efficiency of calcium hydroxide by different methods. METHODS: Eight molar teeth (24 root canals) extracted from the Department of General Dentistry, Shanghai Ninth People's Hospital from October 2023 to February 2024 were collected. Root canal preparation was instrumented by M3 according to standard root canal treatment procedures, then calcium hydroxide was injected into the root canal. One week later, the samples were randomly divided into 3 groups according to different irrigation methods(n=8): lateral opening syringe group, ultrasonic group and sonic vibration group. Micro-CT was used to reconstruct the root canal system before and after irrigation, and independent root canals were marked with different colors. The root canals were divided into upper root segment, middle root segment and apex segment. The volume of calcium hydroxide in each canal was calculated, and the clearance rate of calcium hydroxide was compared among the groups. SPSS 19.0 software package was used for statistical analysis. RESULTS: None of the three methods could completely remove calcium hydroxide from the root canal. When sodium hypochlorite was used as the flushing solution, the removal effect of ultrasonic group and sonic vibration group was significantly better than that of lateral opening syringe group(P<0.05). The removal efficiency of calcium hydroxide by ultrasonic group and sonic vibration group was similar, and the difference was not statistically significant(P>0.05). The removal rate of calcium hydroxide in apical segment was low. CONCLUSIONS: Micro-CT can reconstruct the molar root canal model efficiently for evaluating the removal effect of calcium hydroxide. The removal efficiency of calcium hydroxide in ultrasonic group and sonic vibration group is similar, and both are better than that in lateral syringe group.

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