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25 August 2024, Volume 33 Issue 4 Previous Issue    Next Issue

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CONTENTS 2024, 33 (4):  0-0.  Abstract ( 71 )   PDF (735KB) ( 27 )   Related Articles | Metrics

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Promotor of Chinese Esthetic Dentistry: Deeply Cherishing the Memory of QIU Wei-liu, Member of CAE SUN Shao-xuan 2024, 33 (4):  337-338.  doi: 10.19439/j.sjos.2024.04.001 Abstract ( 81 )   PDF (655KB) ( 26 )   Related Articles | Metrics

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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 2024, 33 (4):  339-344.  doi: 10.19439/j.sjos.2024.04.002 Abstract ( 118 )   PDF (933KB) ( 67 )   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. References | Related Articles | Metrics

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Construction and validation of an immune prognostic risk model in oral squamous cell carcinoma ZHAO Jiao, SUI Bai-yan, LIU Xin, RUAN Min 2024, 33 (4):  345-353.  doi: 10.19439/j.sjos.2024.04.003 Abstract ( 91 )   PDF (3120KB) ( 47 )   PURPOSE: To analyze the immune-related core genes differentially expressed in oral squamous cell carcinoma(OSCC) and construct an immune-related prognostic risk model for OSCC patients. METHODS: Weighted gene co-expression network analysis of RNA sequencing data from OSCC patients in the Cancer Genome Atlas (TCGA) database was conducted to identify immune-related modules and core genes. Core genes associated with immune prognosis were screened using univariate Cox regression analysis and survival analysis to construct an immune-related prognostic risk model for OSCC. The prognostic risk model's predictive ability was evaluated using Kaplan-Meier analysis, receiver operating characteristic curves, and external datasets from GSE41613. The expression of 8 immune prognostic core genes in tumor samples from OSCC patients was detected by real-time quantitative PCR assay(RT-qPCR), and the correlation between risk score and depth of invasion was assessed by calculating risk scores for OSCC patients. Statistical analysis was performed with SPSS 21.0 software package. RESULTS: Prognostic risk model for OSCC was successfully constructed based on 8 immune prognostic core genes(CSF2RA, CLEC4C, COL5A3, CTSG, EDNRA, GPC4, GUCY1A2, ANGPT2). The prognostic risk model demonstrated perfect predictive value validated using Kaplan-Meier analysis, receiver operating characteristic curve, and the GSE41613 dataset. The risk scores of OSCC patients calculated based on this model were positively correlated with the depth of invasion, indicating that the model have the ability to predict the potential risk of OSCC. CONCLUSIONS: An OSCC prognostic risk model is constructed based on the signatures of 8 immune prognostic core genes, which may effectively predict the prognosis of OSCC patients, providing an important reference for immune prevention of OSCC. References | Related Articles | Metrics

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Preparation and efficacy evaluation of carboxymethyl chitosan/β-dextran composite gel for dry socket in rats treatment ZHOU Lin, WANG Hui, XU Jing-bo, ZOU Zi-chuan, MENG Jian 2024, 33 (4):  354-359.  doi: 10.19439/j.sjos.2024.04.004 Abstract ( 73 )   PDF (1408KB) ( 42 )   PURPOSE: To investigate the therapeutic efficacy of a new composite gel of carboxymethyl chitosan/β-dextran in rat dry socket model. METHODS: Carboxymethyl chitosan/oat β-dextran composite gel was prepared, its viscosity, appearance and shape, and stability in oral wet environment were investigated. Staphylococcus aureus was selected for in vitro inhibition test. Blank negative control group, carboxymethyl chitosan/oat β-dextran composite gel group, and iodoform gauze positive control group were established respectively, and the maxillary first molars were extracted to establish a dry socket model in SD rats, to preliminarily evaluate the healing effect of alveolar fossa wounds. The maxillary bone and gingival fixed decalcification were also taken and histopathologically observed for healing as well as immunofluorescence to detect differences in the expression of inflammatory factors between the groups. SPSS 19.0 software package was used for statistical analysis. RESULTS: The compound gel group had obvious antibacterial effect, which can effectively exert local anti-inflammatory and antibacterial efficacy. Compared with the blank control group, visual observation of wound healing, histopathological observation and immunofluorescence inflammatory factor labeling showed that the composite gel group had significant effect on inflammation inhibition and wound healing, which was comparable to the iodoform gauze group. CONCLUSIONS: Carboxymethyl chitosan/oat β-dextran composite gel has significant antibacterial and anti-inflammatory effects and can accelerate the healing of dry socket wounds in rats, which is expected to provide an efficient antibacterial and accelerated healing therapeutic measure for the treatment of clinical dry socket. References | Related Articles | Metrics

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Three-dimensional finite element analysis of different attachment designs for lateral incisors during inward retraction of upper anterior teeth in clear aligner CHEN Jing-cheng, ZHAO Meng-li, CHENG Zhi-heng, LIU Xin 2024, 33 (4):  360-366.  doi: 10.19439/j.sjos.2024.04.005 Abstract ( 94 )   PDF (3163KB) ( 38 )   PURPOSE: To investigate the biomechanical expression of different shapes of attachments on the maxillary anterior teeth during the lingual tooth movement process using clear aligners, providing new insights for orthodontists to improve the clinical design. METHODS: In this study, CBCT data were simulated using the three-dimensional finite element technique. Attachments of various shapes, including no attachment(A1), rectangular attachment(A2), wedge-shaped attachment(A3), and curved arc attachment(A4), were designed on the lateral incisors. Ansys software was employed to calculate the three-dimensional changes in the lateral incisors, dental arch, and clear aligners and the distribution of equivalent stress on the periodontal ligament(von Mises) under the same load conditions. RESULTS: The coronal displacement of the lateral incisors showed the following variations: A1>A4>A3>A2. The sagittal displacement exhibited the following variations: A3>A4>A1>A2. The vertical elongation demonstrated the following variations: A4>A3> A1>A2. The overall displacement of each dental arch displayed an arch-shaped trend. Different regions of the clear aligners exhibited variations in deformation. The von Mises distribution of the periodontal ligament in A1 and A2 group showed similarities, while A3 group exhibited stress concentration only in the lingual area of the root's one-third region. Group A4 experienced significantly higher stress in the cervical region compared to A1 and A2 group. CONCLUSIONS: Rectangular attachments and curved arc attachments possess advantages in coronal control, with rectangular attachments exhibiting the best control effect in vertical control. The area of attachment force and actual displacement efficiency do not have an absolute correlation, as the shape of the force-bearing surface can significantly affect its specific biomechanical expression. References | Related Articles | Metrics

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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 2024, 33 (4):  367-372.  doi: 10.19439/j.sjos.2024.04.006 Abstract ( 78 )   PDF (1582KB) ( 38 )   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. References | Related Articles | Metrics

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Changes of soft tissue profile of maxillary edentulous patients with immediate denture TAO Xing-ru, ZHANG Yun, ZHANG Jia-yuan, WEI Ling-fei, NIE Ping, YU de-dong 2024, 33 (4):  373-380.  doi: 10.19439/j.sjos.2024.04.007 Abstract ( 72 )   PDF (1004KB) ( 39 )   PURPOSE: To compare the changes of soft tissue profile of maxillary edentulous patients before and immediately after implant restoration, as well as to investigate patient satisfaction with postoperative facial appearance. METHODS: A total of 24 patients treated in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January 2018 to December 2020 were selected, the medical history and positive lateral cephalometric film of the patients before and after restoration were collected. Preoperative facial scanning of the patients was performed using the portable 3D facial scanner to design the immediate transitional denture restoration and then perform implant surgery. The collected lateral cephalograms of patients before and after treatment were imported into the computer. The angle measurement items before and after implant immediate denture restoration were analyzed including nasolabial angle, prn'-sn'-ul'(Ls), n'-prn'-sn', N-prn-Pog, Z angle, H angle and line measurements including the distance of upper lip to the E-plane and Sn-Prn. The soft tissue angle and lines were measured by Dolphin Imaging 11.95. Postoperative patient satisfaction with facial appearance was surveyed via telephone questionnaire. SPSS 26.0 software package was used for data analysis. RESULTS: Before restoration of immediate denture, the nasolabial angle and the distance of upper lip to the E-plane of both male and female patients was significantly different from the standard value, and the Z angle of female patients was significantly different from the standard value. After immediate denture restoration, there was no significant difference in nasolabial angle and the distance of upper lip to the E-plane between male and female patients, but there was significant difference in H angle, and nasal tip angle in female patients. After immediate denture restoration, there was no significant difference between the nasolabial angle, H angle and the distance of upper lip to the E-plane in male and female patients after immediate denture restoration, while the soft tissue convexity and Z angle between male and female patients after immediate denture restoration were significantly different compared with the standard value of the attractive individuals. After completion of immediate denture restoration, compared to the edentulous state in maxillary implant treatment, significant changes were observed in nasolabial angle, Z angle, and H angle in patients. The survey of seven questions had a mean score above 3 points (scoring standard 1-5, with 5 being the highest), indicating high patient satisfaction with the appearance after immediate denture restoration. CONCLUSIONS: After immediate denture restoration, the profile of the patient's soft tissue can be improved immediately, and the patient's soft tissue profile can basically return to the normal level, and even meet the standards of beautiful people. It is necessary to guide clinicians to further optimize the function and shape of prostheses in combination with patients' subjective aesthetic demands and individual conditions when conducting implant immediate transition denture restoration. References | Related Articles | Metrics

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Facial soft tissue changes after full-arch implant-supported fixed prostheses restoration in patients with edentulous maxilla ZHANG Yun, TAO Xing-ru, WANG Feng, YU De-dong, WU Yi-qun 2024, 33 (4):  381-386.  doi: 10.19439/j.sjos.2024.04.008 Abstract ( 71 )   PDF (1116KB) ( 37 )   PURPOSE: To investigate the changes of nasolabial soft tissues before and after full-arch implant supported fixed restoration in maxillary edentulous patients and the influencing factors of the changes. METHODS: Fifty patients who underwent full-arch implant fixed restoration in the Department of Second Dental Center of Shanghai Ninth People's Hospital from January 2016 to July 2023 were selected. Patient's medical history, CBCT, and three-dimensional facial scan data were collected before and after restoration. Paired t test or Wilcoxon signed-rank test were used to compare the changes in soft tissues before and after restoration. The correlation between changes and patient's basic information, implant protocol and residual bone parameters were analyzed using bivariate correlation analysis. Akaike information criterion was used to select the multivariate linear regression model of each soft tissue index change. RESULTS: After implant fixed restoration, the upper lip height (sn-sto), the upper vermillion height (ls-sto), and the upper vermilion area (UVA) significantly increased (P<0.01), while the distance from ls to the E-line (ls-E) significantly decreased (P<0.01), the nasolabial angle (∠cm-sn-ls) significantly decreased (P<0.01), and the cutaneous upper lip height(sn-ls) did not change significantly(P>0.05). Except for sn-sto and sn-ls, the remaining soft tissue changes were positively correlated with age (P<0.01). Other residual bone parameters, implant protocol, and gender were not significantly related to each soft tissue change. Multivariate stepwise regression analysis showed that each soft tissue change was broadly related to age and preoperative soft tissue condition, and partially related to bone morphology. CONCLUSIONS: The nasolabial soft tissues of maxillary edentulous patients change significantly after implant fixed restoration, mainly the expansion and protrusion of the red part of the lip. The changes in facial soft tissues are primarily related to the patient's age and pre-existing soft tissue condition, with older patients and those with more atrophic original soft tissue morphology observing more apparent improvements in fullness. The change in lip prominence is also related to the residual bone shape. References | Related Articles | Metrics

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Benign deep lobe parotid tumors: classification in association with localization and surgical approaches MA Xue-hua, XU Jiang, XIA Fei-fei, FANG Tao-li, SUN Zhi-peng 2024, 33 (4):  387-392.  doi: 10.19439/j.sjos.2024.04.009 Abstract ( 60 )   PDF (838KB) ( 19 )   PURPOSE: Benign deep lobe parotid tumors(BDLPT) exhibit a wide range of clinical and imaging features, which closely correlated with the selection of appropriate surgical approaches. This study was aimed to explore variations in surgical management. METHODS: Seventy-five patients with primary BDLPT who underwent surgery in Peking University School and Hospital of Stomatology from August 2014 to August 2020 were included. The imaging data of all cases were retrospectively evaluated. BDLPTs were divided into four types according to the anatomical relationship between the tumor and various structures, and the surgical treatment of each type of tumor was studied. SPSS 24.0 software package was used for statistical analysis. RESULTS: TypeⅠBDLPT(14/75, 18.7%) was located entirely medial to the ramus and the stylomandibular space, with growth extending towards the parapharyngeal space. Type Ⅱ BDLPT(19/75, 25.3%) resided within the retromandibular space, bounded by the ramus, stylomandibular space, mastoid, and retromandibular vein. Type Ⅲ BDLPT(27/75, 36.0%) exhibited an expansive growth pattern, extending from the retromandibular vein to the parapharyngeal space while traversing the stylomandibular space. Type Ⅳ BDLPT(15/75, 20%) was situated inferior to the ear lobe, deep to the facial nerve and retromandibular vein. Transmandibular approach was predominantly employed in type I cases (10/14). Type Ⅲ cases utilized transparotid (14 cases), transmandibular(11 cases), and combined transparotid-transmandibular (2 cases) approaches. Type Ⅱ and Ⅳ cases involved transparotid approaches with concurrent parotidectomy. CONCLUSIONS: The classification of BDLPT offers valuable insights and practical guidance for preoperative treatment planning. References | Related Articles | Metrics

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Risk factors for mesioangular and vertical impactions of mandibular third molars based on logistic regression analysis WANG Rui, ZOU Hui-ru, LIU Qi, CHANG Pan-hui 2024, 33 (4):  393-397.  doi: 10.19439/j.sjos.2024.04.010 Abstract ( 66 )   PDF (962KB) ( 24 )   PURPOSE: To explore the risk factors for mesioangular and vertical impactions of the mandibular third molars and to construct a predictive model based on logistic regression analysis. METHODS: Clinical data of 243 mandibular third molars collected from June 2021 to December 2023 at Tianjin Stomatology Hospital were classified into the eruption group and the impaction group, with the latter including mesioangular and vertical unilateral impactions. The clinical data were subjected to univariate analysis to screen for statistically significant factors, followed by multivariate analysis using logistic regression to further delineate risk factors for mandibular third molar impaction, with the construction of a nomogram for prediction.SPSS 27.0 software package was used for statistical analysis. RESULTS: Totally 243 mandibular third molars were included, and 75 (30.86%) were in the eruption group and 168 (69.14%) in the impaction group. No significant difference was found between the groups regarding age, gender, number of tooth roots, Co-Go, Co-Cop, W2, W3, W4 and L (P>0.05). Significant differences were observed between the eruption and impaction group concerning Nolla, L-6 missing, L-E missing, Co-Pog, Co-Go/Co-Pog, L6-MP, α and W1(P<0.05). Multivariate regression analysis revealed that Nolla, absence of L-6, absence of L-E, Co-Pog, Co-Go/Co-Pog, L6-MP, α and W1 were independent risk factors for mesioangular and vertical impactions of the mandibular third molars (P<0.05). The construction of nomogram demonstrated high predictive accuracy. Analysis of the receiver operating characteristic curve(ROC) indicated that the area under the curve(AUC) for the joint prediction of mesial and vertical impaction of the mandibular third molar by independent risk factors was 0.924, with a 95%CI of 0.887 to 0.960. The sensitivity was reported to be 86.9%, and the specificity was 86.7%. CONCLUSIONS: Nolla, absence of L-6, absence of L-E, Co-Pog, Co-Go/Co-Pog, L6-MP, α and W1 are major risk factors affecting the impaction of mandibular third molars. The use of logistic regression analysis and nomograms can effectively predict the risk of impaction, providing a scientific basis for clinical treatment. References | Related Articles | Metrics

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Effect of minimally invasive circumferential resection on inflammatory response and alveolar crest resorption in patients with dental defect implantation YAO Xu-fei, LAN Bo, JI Yu, ZHOU Xue-jun 2024, 33 (4):  398-402.  doi: 10.19439/j.sjos.2024.04.011 Abstract ( 63 )   PDF (619KB) ( 24 )   PURPOSE: To explore the impact of minimally invasive circumferential resection on inflammatory response and alveolar crest resorption in patients with dental defect implantation. METHODS: A total of 198 patients who received dental implantation in Lishui Hospital of Traditional Chinese Medicine from June 2021 to June 2023 were selected and divided into minimally invasive group (n=100) and traditional group (n=98) according to treatment methods. Minimally invasive surgery was performed in the minimally invasive group and traditional flap surgery was performed in the traditional group.Surgical related indicators, levels of inflammatory factors, pain mediators, alveolar crest bone resorption, implant loosening, quality of life and complication rates were compared between the two groups. SPSS 27.0 software package was used for statistical analysis. RESULTS: The surgery time, postoperative VAS scores and postoperative pain reaction time in the minimally invasive group were significantly lower than those in the traditional group(P<0.05). In the minimally invasive group, the concentrations of IL-8, TNF-α, INF-γ,serum amyloid A(SAA), substance P(SP), calcitonin gene-related peptide(CGRP) and 5-hydroxytryptamine(5-HT) were significantly lower than the traditional group (P<0.05). The amount of alveolar crest bone absorption in minimally invasive group was significantly lower than that in the traditional group(P<0.05). There was no significant differences in implant loosening and retention rates between the two groups(P>0.05). OHIP-14 scores across all dimensions in the minimally invasive group were significantly lower than in the traditional group (P<0.05). There was no significant difference in complication rate between the minimally invasive group and the traditional group (P<0.05). CONCLUSIONS: Compared with the traditional surgery, minimally invasive circumferential surgery has better performance in reducing operation time, postoperative inflammatory factors and pain mediators, alveolar crest and parietal bone absorption and improving oral health, which can be widely used in dental implantation. References | Related Articles | Metrics

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Investigation and analysis of oral health status of children with autism and their parents' cognition TAN Jun-yan, LI Li, YANG Yu-e, WANG Wei, WANG Sun 2024, 33 (4):  403-406.  doi: 10.19439/j.sjos.2024.04.012 Abstract ( 64 )   PDF (507KB) ( 27 )   PURPOSE: To understand the cognitive level of parents of children with autism towards their oral health behaviors and oral health care, and to provide assistance in developing better oral health plans for children with autism. METHODS: Totally 117 children and parents with autism who visited our hospital from January to December 2018 were selected as the experimental group,while 121 non-autistic children during the same period were selected as the control group, the children's oral hygiene was checked. Questionnaire survey was conducted on the oral health behaviors of pediatric patients, including daily brushing frequency, use of toothpaste, assistance from parents in brushing teeth, and frequency of snacking. At the same time, standardized measures were adopted to evaluate the oral health knowledge of parents, obtain their level of understanding oral health-related knowledge, and record the basic situation of parents. SPSS 21.0 software package was used for statistical analysis. RESULTS: The proportion of children with autism who have dental caries and periodontal health problems was relatively high, at 74.36% and 52.14%, respectively. Most pediatric patients had poor oral health behaviors, with a low proportion of brushing teeth ≥2 times per day and consistently using toothpaste, accounting for 17.09% and 13.68%, respectively. In addition, the score of oral health knowledge of parents of children in the experimental group [(6.40±2.55)] was lower than those in the control group [(6.95±2.47)], but there was no significant difference (P>0.05). 93.16% of the children in the experimental group were taken care of full-time by their mother (72.65%) or father (20.51%), and most of the patients's income was not high. The main caregivers and their education level, family income in the control group were significantly different from those in the experimental group (P<0.05). Factors affecting the oral health of autism patients included brushing habits, primary caregivers and parents' highest level of education. CONCLUSIONS: Parents of autistic children have a poor understanding of their children's oral health behaviors, as well as health care. Therefore, education of oral health towards the parents of children with autism should be strengthened with the aim of improving their awareness of oral health and jointly maintaining their health. References | Related Articles | Metrics

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Effect of 2 kinds of appliances on anterior tooth root and alveolar bone in patients with mild to moderate overcrowding of ClassⅠmalocclusion HUO Mei-ling, LEI Ying, XIN Xin, ZHANG Ying, WANG Rui-mei 2024, 33 (4):  407-410.  doi: 10.19439/j.sjos.2024.04.013 Abstract ( 62 )   PDF (493KB) ( 21 )   PURPOSE: To analyze the effects of fixed appliance and invisible appliance without bracket on anterior tooth root and alveolar bone in patients with mild to moderate overcrowding of Class Ⅰmalocclusion. METHODS: A total of 120 patients with mild to moderate dental crowding were selected from January 2018 to February 2022,and divided into control group and experimental group by random number table method, with 60 cases in each group. The control group was treated with traditional fixed appliance, while the experimental group was treated with invisible appliance without bracket. Cone-beam CT(CBCT) was taken before and 12 months after treatment to measure the root length and alveolar bone height and thickness of maxillary central incisor teeth, height of alveolar bone of anterior teeth lip and lingual side and cusp teeth in both groups. Statistical analysis was performed with SPSS 22.0 software package. RESULTS: The root length changes of maxillary central incisor, lateral incisor and cusp teeth in the experimental group were significantly lower than those in the control group before and after treatment(P<0.05). The alveolar bone height changes in the labial side and lingual palatine side of upper anterior teeth, labial side and lingual palatine side of inferior anterior teeth in the experimental group before and after treatment were significantly lower than those in the control group(P<0.05). The thickness changes of labiolingual alveolar bone at the neck, middle root and apex of upper and inferior anterior teeth in the experimental group were significantly lower than those in the control group before and after treatment(P<0.05). CONCLUSIONS: Compared with fixed appliance, invisible appliance without bracket can reduce root resorption and the loss of alveolar bone height and thickness in the treatment of Class I patients with mild to moderate dental crowding. References | Related Articles | Metrics

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Correlations of salivary ion concentration, Streptococcus and Bifidobacterium in children with caries BIAN Hui-hui, LIU Yu, HUANG Qing, WANG Yan-ping, CHENG Dong-dong, WU Guo-min 2024, 33 (4):  411-414.  doi: 10.19439/j.sjos.2024.04.014 Abstract ( 60 )   PDF (583KB) ( 23 )   PURPOSE: To analyze the correlation between the changes in salivary ion concentration, Streptococcus and Bifidobacterium in children with dental caries and the severity of the disease. METHODS: Eighty children with dental caries treated from May 2022 to April 2023 were selected as the experimental group. According to the DMFT, they were divided into mild group (DMFT≤15%, n=35) and severe group (DMFT>15%, n=45). Another 80 children without dental caries were selected as the control group. The calcium ion concentration in saliva was detected by methanol-permeabilized calciometric method, the level of Streptococcus and Bifidobacterium was detected by real-time single-quantity PCR technology, and the correlation between DMFT and salivary calcium ion concentration, Streptococcus and Bifidobacterium was analyzed by Pearson correlation analysis. The diagnostic value of salivary calcium ion concentration, Streptococcus and Bifidobacterium for the severity of dental caries in children was evaluated by the receiver operating characteristic curve(ROC), and the area under the curve(AUC) was calculated. SPSS 22.0 software package was used for statistical analysis. RESULTS: The level of salivary calcium ion concentration, Streptococcus mutans, Streptococcus sobrinus and Bifidobacterium in the experimental group was significantly higher than that in the control group(P<0.05), and significantly higher in the severe group than in the mild group(P<0.05). DMFT was significantly positively correlated with salivary calcium ion concentration, Streptococcus and Bifidobacterium (P<0.05). Based on DMFT, ROC curve was prepared, and AUCs of salivary calcium ion concentration, Streptococcus mutans, Streptococcus sobrinus and Bifidobacterium for assessing the severity of dental caries in children were 0.760, 0.658, 0.718 and 0.705, respectively. CONCLUSIONS: Increased salivary ion concentration, Streptococcus sobrinus, Streptococcus mutans and Bifidobacterium levels are related to dental caries in children, and are positively correlated with the severity of the disease, which has a certain value for assessing the severity of the disease. References | Related Articles | Metrics

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Analysis of latent class and heterogeneous associations of oral health behaviors with preschool children caries ZHAI Li-yun, YAO Ning, KONG Jia-xin, DING Zhi-min, XU Yang, ZHAO Chao-nan 2024, 33 (4):  415-420.  doi: 10.19439/j.sjos.2024.04.015 Abstract ( 59 )   PDF (879KB) ( 29 )   PURPOSE: To determine the latent class and heterogeneous associations of oral health behaviors (OHB) with caries in preschool children aged 3-6 years, and to develop effective oral health interventions for improving their health status. METHODS: Latent class analysis(LCA) was applied to classify eight OHBs in three dimensions: oral hygiene, dietary habits, and preventive protection in 595 preschool children. Optimal classes were determined using model fitting and explanatory metrics, and marginal effects were estimated using bivariate association and multivariate regression models. The correlation between OHBs and caries was explored using Chi-square and correspondence analysis with SPSS 27.0 software package. RESULTS: Among 595 preschool children, caries prevalence was 54%, and OHBs were classified into two latent classes: favorable (88%) and unfavorable (12%). Unfavorable OHBs were associated with higher caries prevalence (58% vs. 52%), poorer caries status (mean dmft: 3.52 vs. 2.44), and lower regular examination experience (63% vs. 66%) compared to favorable OHBs. The difference in caries severity distribution between the two classes was statistically significant (P<0.05). CONCLUSIONS: Oral health behaviors in preschool children are heterogeneous and associated with caries. Effective interventions for improving OHBs in preschool children should be tailored according to this heterogeneity. References | Related Articles | Metrics

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Effect of dual-wavelength laser combined with bioceramics iRoot SP to assist molar root canal treatment WANG Mian, YAO Li-li, HAN Shuang, DA Hai-qin, HOU Ying 2024, 33 (4):  421-425.  doi: 10.19439/j.sjos.2024.04.016 Abstract ( 68 )   PDF (831KB) ( 24 )   PURPOSE: To investigate the effect of dual-wavelength laser combined with bioceramics material iRoot SP on molar root canal treatment. METHODS: A total of 104 patients receiving root canal treatment from January 2020 to June 2023 were selected and divided into control group and experimental group according to random number table method, with 52 cases in each group. The control group was treated with iRoot SP paste, and the experimental group was treated with dual-wavelength laser(Nd:YAG and Er:YAG) combined with iRoot SP paste. The total effective rate, pain degree and complications were compared. Serum interleukin-6 (IL-6), interleukin-17(IL-17), tumor necrosis factor-α(TNF-α), bleeding index(BI), depth of periodontal probing(PD) and clinical attachment level(CAL) were observed before treatment, 6 weeks and 12 weeks after treatment. SPSS 22.0 software package was used for statistical analysis. RESULTS: The total effective rate of the experimental group was significantly higher than that of the control group, and the pain degree after root canal filling was significantly lower than the control group(P<0.05). The levels of IL-6, IL-17, TNF-α, BI, PD and CAL in the experimental group were significantly lower than those in the control group at 6 and 12 weeks after treatment (P<0.05). CONCLUSIONS: Dual wavelength laser combined with bioceramic material iRoot SP has a better effect in the treatment of molar root canal, which is conducive to reducing periodontal inflammation and pain. References | Related Articles | Metrics

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Evaluation of the effect of bone nail and artificial periosteum combined with iliac cancellous bone grafting in repairing cleft lip and palate with alveolar cleft during dental replacement TANG Kun-lun, HE Xiao-ling, CHEN Dan 2024, 33 (4):  426-431.  doi: 10.19439/j.sjos.2024.04.017 Abstract ( 60 )   PDF (940KB) ( 31 )   PURPOSE: To evaluate the effect of bone nail and artificial periosteum combined with iliac cancellous bone grafting in repairing cleft lip and palate with alveolar cleft during dental replacement. METHODS: The clinical data of 82 children with cleft lip and palate with alveolar cleft during dental replacement period were retrospectively analyzed from January 2020 to December 2023, and were divided into control group (iliac cancellous bone grafting alone, n=42) and experimental group (combined iliac cancellous bone grafting with bone nail and artificial periosteum, n=40) according to the operation method. The viable bone volume in bone graft area, absorption rate of whole bone graft and different bone graft areas, success rate of bone graft, survival rate of bone graft and complications were compared between the two groups. SPSS 25.0 software package was used for statistical analysis. RESULTS: The surviving bone volume in the bone graft area was significantly larger in the experimental group 3 and 9 months after operation(P<0.05). There was no significant difference in viable bone volume in bone graft area between the two groups 9 months and 3 months after surgery (P>0.05). The bone graft absorptivity of the experimental group was significantly lower than that of the control group 3, 9 months and 3-9 months after surgery(P<0.05), and there was no significant difference between the two groups at 3, 9 months after surgery(P>0.05). The absorption rate of bone graft in 1/2 area of nasal cavity, 1/2 area of alveolar ridge, 1/2 area of lip and 1/2 area of palate in the experimental group was significantly lower than that in the control group 3 and 9 months after operation(P<0.05). The absorptivity of bone graft in 1/2 area of alveolar ridge was significantly higher than that in 1/2 area of nasal cavity, and the absorptivity of bone graft in 1/2 area of palatal side was significantly higher than that in 1/2 area of lip in both groups (P<0.05). The success rate and survival rate of bone grafting in the experimental group were significantly higher than those in the control group(P<0.05). The complication rate of the experimental group was significantly lower than that of the control group (P<0.05). CONCLUSIONS: Bone nail and artificial periosteum combined with iliac cancellous bone graft can effectively repair cleft lip and palate with alveolar cleft during dental replacement, reduce bone absorption rate and complications, and improve bone formation effect. Meanwhile, postoperative bone mass absorption mainly occurs within 3 months after surgery, and mainly occurs in the alveolar crest area and palatine area. References | Related Articles | Metrics

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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 2024, 33 (4):  432-437.  doi: 10.19439/j.sjos.2024.04.018 Abstract ( 65 )   PDF (648KB) ( 31 )   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. References | Related Articles | Metrics

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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 2024, 33 (4):  438-442.  doi: 10.19439/j.sjos.2024.04.019 Abstract ( 59 )   PDF (620KB) ( 28 )   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. References | Related Articles | Metrics

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Narrative medicine practice for dental students during clinical internship HE Wen-yao, ZHENG Pei 2024, 33 (4):  443-448.  doi: 10.19439/j.sjos.2024.04.020 Abstract ( 66 )   PDF (755KB) ( 35 )   PURPOSE: To explore the effect of narrative medicine teaching practice on the narrative ability and empathy ability of dental interns and establish an effective narrative medicine teaching system. METHODS: From June 2022 to May 2023, atotal of 34 dental undergraduate students participating in clinical practice were divided into two groups, with 14 students in experimental group and 20 in control group. During clinical internships, the experimental group took narrative medicine into practice including theoretical lectures, close reading, parallel chart, seminars and so on. Interpersonal Reactivity Index(IRI) was used to evaluate the empathy of the students in the two groups, and a questionnaire survey was conducted on the narrative medicine practice of the experimental group. SPSS 12.0 software package was used for data analysis. RESULTS: The total score and module scores of empathy scale in the experimental group did not change significantly after the practice compared with before the practice. The score of "personal distress" module in the control group decreased significantly after the practice (P<0.05), indicating that students in the control group who did not receive narrative education had a decrease in empathy after clinical practice. The questionnaire and parallel charts reflected that the interns' narrative ability and the understanding for medical psycho-social factors of experimental group students had been enhanced. CONCLUSIONS: Narrative medicine practice is helpful to improve narrative ability and empathy ability, cultivate professional quality and ease the doctor-patient relationship. It should be continuously promoted during the dental undergraduate teaching and dentist’s practicing career. References | Related Articles | Metrics