Objective: To evaluate the effect of the application of a self-developed three-dimensional visualized model of impacted tooth for surgical extraction in undergraduate oral experimental teaching. Methods: Forty-one undergraduates majoring stomatology of Tongji University from 2018 [19 males and 22 females, aged (22.4±0.8) years] were enrolled and randomly divided into the conventional group and the experimental group. Students of the conventional group (21 students including 8 males and 13 females) received a teaching protocol for the surgical extraction of impacted tooth including theoretical lectures, watching operation videos, and operating on head-simulator teaching systems. Students of the experimental group (20 students including 11 males and 9 females) received an additional training of resistance assessment and surgical extraction using the three-dimensional visualized model of impacted tooth before operating on the head simulators. After class, a questionnaire survey was carried out among students, and the operation results on the head simulators were evaluated by the teacher. Results: The results of the questionnaire showed that the students in the experimental group were rated higher than those in the traditional group in terms of being able to imagine the relationship between impacted teeth and adjacent structures (U=114.00, P=0.006), avoiding damage to adjacent teeth (U=87.00, P<0.001) and inferior alveolar nerve during tooth extraction (U=111.50, P=0.006), and being more confident in clinical operations in the future (U=120.00, P=0.013). According to the evaluation results of tooth extraction on the head simulators, there was no significant difference in the operation time between the two groups (U=138.50, P=0.056). In the experimental group, 5% (1/20) caused adjacent tooth loosening and 15% (3/20) caused the excessive bone defect, which was less than those in the traditional group [38% (8/21) and 48% (10/21), respectively] (P=0.021; P=0.043). There was no significant difference in the incidence of grinding out the deep bone of impacted teeth between the two groups (P=0.232). Conclusions: The application of three-dimensional visualized model of impacted tooth for surgical extraction in undergraduate oral experimental teaching had achieved good results and was worth popularizing.
Female ; Humans ; Male ; Molar, Third/surgery* ; Operative Time ; Students ; Tooth Extraction/methods* ; Tooth, Impacted/surgery*

Objective: To evaluate the risk factors of inferior alveolar nerve injury (IANI) after surgical removal of the mandibular third molars (M3) and present a new risk scoring system to predict the probability of IANI. Methods: Patients who underwent extraction of M3 in the Stomatology Hospital, Zhejiang University School of Medicine from April 2017 to December 2019 were involved. The investigators enrolled a sample composed of 949 mandibular third molars. Prediction model was used for univariate and multivariate analysis of gender, age, M3, inferior alveolar canal (IAC), and the contact between M3 and IAC, to assess the risk factors of IANI. Combined with the risk factors determined by the outcomes of prediction model, the risk scoring system was constructed. The diagnostic performance of each cut-off score was examined to conduct a risk stratification of IANI risk scores. The predictive ability and reliability of the model were evaluated. Results: In prediction model, twenty nine cases (4.4%, 29/664) experienced postoperative IANI. Number of root (P<0.01), depth of impaction (P<0.05), contact between M3 and IAC (P<0.01) and their contact position (P<0.05) were statistically significant as contributing risk factors of IANI. Specifically, the incidence of temporary IANI was higher in those who aged under 25 years (P<0.001), while female suffer more permanent injury (P<0.05). Based on the IANI risk scoring system, patients were stratified into low-risk, middle-risk and high-risk groups at cutoff scores of 3 and 4. The area under the receiver operator characteristic curve of the risk scoring system were 0.81 [95%CI (0.70-0.90), P=0.002] and 0.80 [95%CI (0.68-0.92), P=0.007] towards good discrimination. Conclusions: Age, gender, number of root, depth of impaction, and contact between M3 and IAC were risk factors of IANI. IANI risk scoring system might help in preoperative assessment, recognition of high-risk cases and decision-making to reduce IANI.
Aged ; Female ; Humans ; Mandible/surgery* ; Mandibular Nerve ; Molar, Third/surgery* ; Reproducibility of Results ; Risk Factors ; Tooth Extraction/adverse effects* ; Trigeminal Nerve Injuries/etiology*

OBJECTIVE: To evaluate the relevant indicators affecting difficulty in the extraction of impacted mandibular third molars and score difficulty of different operation and risk indicators, so as to build an intuitive and accurate scale to help operators make more accurate analysis and prediction of difficulty before the operation. METHODS: Based on literature and the clinical review, the difficulty indicators of tooth extraction were summarized. Firstly, 10 doctors from Peking University School and Hospital of Stomatology who had been engaged in alveolar surgery for a long time established an expert nominal group, and then rated whether the summarized indicators needed to be retained in the form of face-to-face questionnaires. A level 1 and 2 item frame for evaluating difficulty in the tooth extraction was formed after discussion; Then Delphi method was used to send a questionnaire to 30 experts by e-mail. After two rounds of scoring and modification, the scale of difficulty in the extraction of impacted mandibular third molars was formed. RESULTS: The recycling rate of two rounds of questionnaires was 100.0%, which showed that the experts were very enthusiastic about the study; The authority coefficients (Cr) of the two rounds of Delphi expert consultation were both 0.92, which showed that the results were representative and authoritative. After two rounds of grading and revision, the variable coefficient (CV) decreased and the Kendall's concordance coefficient (W) increased, which were statistically significant: In the first round, the CV was 0.24 and W was 0.56 (P < 0.001), and in the second, the CV was 0.19 and W was 0.72 (P < 0.001), which indicated that there was a good convergence among the expert opinions. Finally, a scale of difficulty in the tooth extraction containing 12 items at level A and 37 items at level B was formed, including operation difficulty indicators, risk difficulty indicators and common difficulty indicators. CONCLUSION Based on comprehensive literature retrieval, the study has put forward the concept that difficulty in the extraction of impacted mandibular third molars is composed of operation difficulty and risk difficulty. Using Delphi method, the long-term clinical experience and professional knowledge of experts are transformed into quantitative indicators as a scoring scale. The scale has certain representativeness and authority.
Delphi Technique ; Humans ; Mandible/surgery* ; Molar, Third/surgery* ; Tooth Extraction ; Tooth, Impacted/surgery*

Considering the adverse effects of nonimpacted third molars (N-M3s) on the periodontal health of adjacent second molars (M2s), the removal of N-M3s may be beneficial to the periodontal health of their neighbors. This study aimed to investigate the clinical, immunological, and microbiological changes of the periodontal condition around M2s following removal of neighboring N-M3s across a 6-month period. Subjects with at least one quadrant containing an intact first molar (M1), M2, and N-M3 were screened and those who met the inclusion criteria and decided to receive N-M3 extraction were recruited in the following investigation. M2 periodontal condition was interrogated before M3 extraction (baseline) and at 3 and 6 months postoperatively. Improvements in clinical periodontal indexes of M2s in response to their adjacent N-M3 removal, along with changes in inflammatory biomarkers among gingival crevicular fluid (GCF) and the composition of subgingival plaque collected from the distal sites of the M2s of the targeted quadrant were parallelly analyzed. Complete data of 26 tooth extraction patients across the follow-up period were successfully obtained and subsequently applied for statistical analysis. Compared to the baseline, the periodontal condition of M2s was significantly changed 6 months after N-M3 removal; specifically, the probing depth of M2s significantly reduced (P < 0.001), the matrix metalloproteinase (MMP)-8 concentration involved in GCF significantly decreased (P = 0.025), and the abundance of the pathogenic genera unidentified Prevotellaceae and Streptococcus significantly decreased (P < 0.001 and P = 0.009, respectively). We concluded that N-M3 removal was associated with superior clinical indexes, decreased GCF inflammatory biomarkers, and reduced pathogenic microbiome distribution within the subgingival plaque. Although the retention or removal of N-M3s continues to be controversial, our findings provide additional evidence that medical decisions should be made as early as possible or at least before the neighboring teeth are irretrievably damaged.
Humans ; Molar/surgery* ; Molar, Third/surgery* ; Periodontal Diseases ; Periodontal Index ; Tooth Extraction

OBJECTIVES: This prospective study was performed to evaluate whether the distal-triangular flap was a practical alternative surgical approach for extracting mandibular third molars. METHODS: Sixty participants with impacted mandibular third molars were randomly divided into three groups: group A, distal-triangular flap; group B, Szmyd flap; and group C, envelope flap. The impacted third molars were extracted by the corresponding flapping method. During a three-month follow-up observation after the extraction, the postoperative pain, swelling, mouth opening, and periodontal status were recorded and analyzed by ANOVA and chi-square tests. RESULTS: The 60 participants had successful extraction and 3-month follow-up observation. No participant suffered from postoperative infections, lower lip disorder, or tongue sensory disorders. No statistical differences were found in the postoperative symptoms and signs of the three flap designs, such as postoperative pain, swelling, mouth opening, and periodontal status ( CONCLUSIONS The distal-triangular flap was as safe and reliable as the Szmyd and envelope flaps but more advantageous because of its convenient operative field exposure and low requirement for the patient's mouth opening. Thus, the distal-triangular flap is one of the alternative flap options for extracting impacted mandibular third molars.
Humans ; Mandible/surgery* ; Molar, Third/surgery* ; Prospective Studies ; Tooth Extraction ; Tooth, Impacted/surgery*

OBJECTIVES: This study aims to analyze the effectiveness of platelet-rich fibrin (PRF) in mandibular third molar extraction and provide suggestions for alleviating postoperative complications. METHODS: Pubmed, EMBASE, Web of Science, and SinoMed were searched electronically on February 2020. Randomized controlled trials focusing on PRF usage in mandibular third molar extraction were included. Reviewers assessed the risk of bias in the included literature and extracted data independently using the criteria recommended by the Cochrane Collaboration. Meta-analysis was performed using RevMan 5.3 and STATA 13.0. RESULTS: Twenty-one studies were included, comprising 991 patients who had mandibular third molar extraction. The topical application of PRF effectively reduced pain after extraction [MD=-12.06, 95%CI (-21.42, -2.71), CONCLUSIONS Limited clinical evidence indicates that applying PRF after mandibular third molar extraction could reduce pain, swelling, trismus and the occurrence of dry socket and promote soft tissue healing. However, the effect of PRF on bone healing requires further large-scale randomized controlled trials and unified measurement criteria.
Humans ; Mandible ; Molar, Third/surgery* ; Platelet-Rich Fibrin ; Tooth Extraction ; Tooth, Impacted

The lingual nerve (LN) is a branch of the mandibular division of the trigeminal nerve, and its injury is one of the major complications during oral surgery. This study aims to investigate the anatomy of the LN in the lower third molar area. Twenty sides from ten fresh-frozen adult cadaveric Caucasian heads were examined to measure the diameter of the LN. The mean diameter of the LN was 2.20±0.37 mm (range, 1.61–2.95 mm). There were no statistically significant differences in the measurements between sexes, sides, or tooth status (dentulous or edentulous). Understanding the anatomical features of the LN is essential for performing any surgical procedure in the oral region.
Adult ; Cadaver ; Head ; Humans ; Lingual Nerve ; Mandibular Nerve ; Molar, Third ; Surgery, Oral ; Tooth ; Trigeminal Nerve

OBJECTIVES: The goal of the study was to investigate the clinical effects of amoxicillin-clavulanic acid (500+125 mg) with metronidazole 400 mg administered three times daily (Group I) versus azithromycin 500 mg administered once daily and with metronidazole 400 mg three times daily (Group II) for the prevention of postoperative infection following mandibular third molar surgical removal. MATERIALS AND METHODS: The study design was a single-center prospective study. Patients who reported to the Department of Oral and Maxillofacial Surgery between February 2015 and January 2017 for removal of mandibular third molar were screened, and 108 patients were chosen. One surgeon carried out all procedures. Patients were prescribed antibiotics until the two groups contained a similar number of cases. RESULTS: Our data showed that Group II had fewer incidences of surgical site infection, but with no statistical significance. CONCLUSION: Although both treatments are used routinely after removal of the mandibular third molar, neither is significantly better than the other.
Amoxicillin ; Amoxicillin-Potassium Clavulanate Combination* ; Anti-Bacterial Agents ; Antibiotic Prophylaxis ; Azithromycin* ; Humans ; Incidence ; Metronidazole* ; Molar, Third* ; Prospective Studies ; Surgery, Oral ; Surgical Wound Infection

OBJECTIVES: The primary purpose of this study was to investigate the factors related with additional administration of sedative agent during intravenous conscious sedation (IVS) using midazolam (MDZ). The secondary purpose was to analyze the factors affecting patient satisfaction. MATERIALS AND METHODS: Clinical data for 124 patients who had undergone surgical extraction of mandibular third molar under IVS using MDZ were retrospectively investigated in this case-control study. The initial dose of MDZ was determined by body mass index (BMI) and weight. In the case of insufficient sedation at the beginning of surgery, additional doses were injected. During surgery, peripheral oxygen saturation, bispectral index score (BIS), heart rate, and blood pressure were monitored and recorded. The predictor variables were sex, age, BMI, sleeping time ratio, dental anxiety, Pederson scale, and initial dose of MDZ. The outcome variables were additional administration of MDZ, observer's assessment of alertness/sedation, intraoperative amnesia, and patient satisfaction. Descriptive statistics were computed, and the P-value was set at 0.05. RESULTS: Most patients had an adequate level of sedation with only the initial dose of MDZ and were satisfied with the treatment under sedation; however, 19 patients needed additional administration, and 13 patients were unsatisfied. In multivariable logistic analysis, lower age (odds ratio [OR], 0.825; P=0.005) and higher dental anxiety (OR, 5.744; P=0.003) were related to additional administration; lower intraoperative amnesia (OR, 0.228; P=0.002) and higher BIS right before MDZ administration (OR, 1.379; P=0.029) had relevance to patient dissatisfaction. CONCLUSION: The preoperative consideration of age and dental anxiety is necessary for appropriate dose determination of MDZ in the minor oral surgery under IVS. The amnesia about the procedure affects patient satisfaction positively.
Amnesia ; Blood Pressure ; Body Mass Index ; Case-Control Studies ; Conscious Sedation* ; Dental Anxiety ; Drug Dosage Calculations ; Heart Rate ; Humans ; Midazolam* ; Molar, Third* ; Oxygen ; Patient Satisfaction ; Retrospective Studies ; Risk Factors* ; Surgery, Oral

OBJECTIVES: The aim of this study was to evaluate the implication of third molars in postoperative complications of mandibular angle fracture with open reduction and internal fixation (ORIF). MATERIALS AND METHODS: Data were collected on patients who presented with mandibular angle fracture at our Department of Oral and Maxillofacial Surgery between January 2011 and December 2015. Of the 63 total patients who underwent ORIF and perioperative intermaxillary fixation (IMF) with an arch bar, 49 patients were identified as having third molars in the fracture line and were followed up with until plate removal. The complications of postoperative infection, postoperative nerve injury, bone healing, and changes in occlusion and temporomandibular joint were evaluated and analyzed using statistical methods. RESULTS: In total, 49 patients had third molars in the fracture line and underwent ORIF surgery and perioperative IMF with an arch bar. The third molar in the fracture line was retained during ORIF in 39 patients. Several patients complained of nerve injury, temporomandibular disorder (TMD), change of occlusion, and postoperative infection around the retained third molar. The third molars were removed during ORIF surgery in 10 patients. Some of these patients complained of nerve injury, but no other complications, such as TMD, change in occlusion, or postoperative infection, were observed. There was no delayed union or nonunion in either of the groups. No statistically significant difference was found between the non-extraction group and the retained teeth group regarding complications after ORIF. CONCLUSION: If the third molar is partially impacted or completely nonfunctional, likely to be involved in pathologic conditions later in life, or possible to remove with the plate simultaneously, extraction of the third molar in the fracture line should be considered during ORIF surgery of the mandible angle fracture.
Humans ; Mandible ; Mandibular Fractures ; Molar, Third* ; Postoperative Complications* ; Surgery, Oral ; Temporomandibular Joint ; Temporomandibular Joint Disorders ; Tooth