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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.

Introduction: Impacted third molars often cause pain, infections, swelling, and functional limitations. This study is an attempt to assess impacted third molars-related symptoms affecting quality of life using standardised Nepali version of oral health impact profile-14 (OHIP-14) questionnaire., Methods: This descriptive cross-sectional study was conducted at Kathmandu Medical College Teaching Hospital from October 2021 to February 2022 after institutional ethical approval. Patients with impacted third molars were included by convenience sampling technique. Patients with psychiatric illness, taking psychotropic drugs, pregnant, and lactating females were excluded. third molars-related symptoms were recorded in OHIP-14 questionnaire. Data entered in Microsoft Excel sheet were analysed. The findings have been presented as frequency, percent, mean, and standard deviation. The point estimate was calculated at a 95% Confidence Interval., Results: Mean OHIP-14 score of participants was 21.77±11.59. Due to TM, "pain in the mouth" had score of (2.33±1.24) and followed by "uncomfortable experience on eating food" (2.12±2.15). Among seven OHIP-14 dimensions, "physical pain" with two items OHIP3 and OHIP4 had score of 4.53±2.19 implying most participants had "quite a lot" of physical pain due to TM: OHIP3 = 194 (50.2%) and OHIP4 = 183 (47.3%)., Conclusions: Impacted third molars-related symptoms were affecting quality of life of participants.

Background: Dental autotransplantation (DAT) is defined as the replacement or direct transfer of an impacted, semi-impacted or erupted tooth to a donor site, either to a post-extraction socket or to a surgically created socket within the same individual. The use of new technological advances, such as 3-D dental models based on computer-aided design, among others, have been reported to improve the success rate of DAT. Therefore, we aimed to perform a systematic review to explore the possible benefits that the use of these innovative techniques can provide when applied to DAT., Material and Methods: The literature search was conducted in PubMed, Scopus, and Web of Science databases following the PRISMA guidelines. The research question was: "Are computerized technological advancements a useful tool for improving the success of third molar autotransplantation technique?, Results: The initial literature search identified 195 articles, of which only 11 were included for qualitative analysis. All studies used 3D dental models based on computer-aided design data. Surgical guides and stereolithographic models were used by 4 and 1 study respectively. A total of 91 transplanted teeth were evaluated, out of which only 88 were considered within the parameters of clinical success (96.7%). Only 7 out of the 11 articles reported the specific autotransplanted tooth, being mandibular third molars the most prevalent autotransplanted teeth., Conclusions: Although the application of new technologies for DAT increases the success rate of this technique, further primary studies are still needed to address long-term teeth survival rates and complications. The cost and availability to implement the integration of these techniques to DAT may be a variable to consider, as this can be a limitation for some patients or for low-income countries.

Due to the limitations of eruption time and space, third molars (M3s) are often impacted and induce a variety of oral diseases, bringing adverse effects on the health of their adjacent second molars (M2s). For a long time, a large number of studies have focused on the harm of impacted M3s (I-M3s) to the health of their adjacent teeth, while less attention has been paid to nonimpacted M3s (N-M3s) that have already erupted. In recent years, however, a growing number of studies and evidences have shown that the existence of N-M3s is also an important risk factor for various diseases of their adjacent teeth, whose hazard has not been taken seriously by dentists and patients. Based on the latest results of both domestic and international researches as well as our group, this review summarizes and explains the effects of N-M3s on the periodontal homeostasis and periodontal health of adjacent M2s, so as to provide reference for clinical decision-making of N-M3s and the healthy maintenance of their adjacent teeth.

Objectives: To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference., Methods: CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05)., Results: The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN., Conclusions: The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal., Clinical Relevance: Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: The aim of the study was to evaluate the efficacy of traditional supervised learning (SL) and semi-supervised learning (SSL) in the classification of mandibular third molars (Mn3s) on panoramic images. The simplicity of preprocessing step and the outcome of the performance of SL and SSL were analyzed., Methods: Total 1625 Mn3s cropped images from 1000 panoramic images were labeled for classifications of the depth of impaction (D class), spatial relation with adjacent second molar (S class), and relationship with inferior alveolar nerve canal (N class). For the SL model, WideResNet (WRN) was applicated and for the SSL model, LaplaceNet (LN) was utilized., Results: In the WRN model, 300 labeled images for D and S classes, and 360 labeled images for N class were used for training and validation. In the LN model, only 40 labeled images for D, S, and N classes were used for learning. The F1 score were 0.87, 0.87, and 0.83 in WRN model, 0.84, 0.94, and 0.80 for D class, S class, and N class in the LN model, respectively., Conclusions: These results confirmed that the LN model applied as SSL, even utilizing a small number of labeled images, demonstrated the satisfactory of the prediction accuracy similar to that of the WRN model as SL., Competing Interests: Competing interestsThe authors declare no conflict of interest.

Aim: This study was performed to histologically evaluate peri-coronal tissues of partially impacted and erupted third molars that did not exhibit pathologic peri-coronal radiolucency., Materials and Methods: Healthy patients with erupted or partially erupted (with part or all of the dental crown present in the oral cavity) mandibular third molars (classified as IA and IIA according to the Pell and Gregory classification) and vertically positioned (according to the Winter classification or erupted third molars) associated with peri coronal radiolucency of equal to or less than 2.5 mm. Associated with third molar surgery, tissue sampling from the distal area was performed, which was subjected to an anatomopathological examination to determine the histological nature., Results: One hundred teeth (100 patients) were selected, and 100 specimens were analyzed. 53% of the sample were included in the non-pathological group and 47% showed pathological changes (fibrotic tissue (n 15), periodontal cyst-like (n 9), squamous epithelial metaplasia (4 cases), islands of odontogenic epithelial residues organized micro-cyst with keratocystic/ameloblastic appearance (4 cases), granulation tissue (n 8), giant cell tumour (n 4) and lobular capillary hemangioma (n 4)). Pathological changes did not have differences in incidence between the gender (p value = 0.85) and did not show any correlation with age, (p value = 0,96)., Conclusions: These findings suggest that radiographic appearance may not be a reliable indicator of the absence of disease within a dental follicle. Therefore, clinicians should pay attention to or follow up on even peri-coronal radiolucency of less than 2.5 mm., (© 2023. The Author(s).)

From the second half of the 18th century to the last third of the 19th century, a period of about 100 years, perpendicular (vertical) extraction, became an ideal for many authors, since molars were the most difficult teeth to remove. However, extraction instruments available at that time, caused pronounced damage to the alveolar bone and gingiva. For many authors and clinicians, vertical extraction was the only way to meet this challenge. This approach to tooth removal, while viable, came to an end when anatomically shaped forceps, adapted to the different morphologies of the various teeth were introduced, thereby changing 19th century dentistry with a new standard for tooth removal., (Copyright 2023 © American Academy of the History of Dentistry.)

Background: The anatomical position of the mandibular third molars (M3s) is located in the distal-most portions of the molar area. In some previous literature, researchers evaluated the relationship between retromolar space (RS) and different classifications of M3 in three‑dimensional (3D) cone-beam computed tomography (CBCT)., Methods: Two hundred six M3s from 103 patients were included. M3s were grouped according to four classification criteria: PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP) which was fitted by the least square method and the occlusal plane (OP) as reference planes. SPSS (version 26) was used to analyze the data., Results: In all criteria evaluated, RS decreased steadily from the crown to the root (P < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (P < 0.05). As the degree of mesial tilt decreased, RS appeared an increasing trend (P < 0.05). RS in classification criteria of buccolingual angle had no statistical difference (P > 0.05)., Conclusions: RS was associated with positional classifications of the M3. In the clinic, RS can be evaluated by watching the Pell&Gregory classification and mesial angle of M3., (© 2023. The Author(s).)

Objective: The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion., Materials and Methods: The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10 mm (mandibular retromolar space length in root level, RL in2,4,6,8,10 ) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10 mm (width of the mandibular retromolar space, BW 2,4,6,8,10 / width of the second molar distal root, TW 2,4,6,8,10 ) from the CEJ., Results: RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05)., Conclusions: Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization., Clinical Relevance: When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

While synthetic implants represent a significant contribution to the advancement of dental medicine, they are associated with high costs, potential complications, and time delays. With autotransplantation, the patient is both donor and recipient of a living tooth; in the ideal case, this procedure transfers a healthy, nonfunctional tooth to a functional position. The aim of this article is to review the literature surrounding autotransplantation and present a successful case with the hope of increasing awareness of this approach to tooth replacement. A 20-year-old patient presented with a maxillary right second molar showing poor prognosis for restoration, and the patient's financial difficulties rendered extraction the only treatment option. The patient's fully soft tissue-impacted maxillary right third molar was atraumatically extracted and transplanted as a replacement for the second molar. The autotransplantation technique was enhanced via use of bone allograft to adapt the distal portion of the socket to the transplant, immediately reestablishing a healthy bony anatomy. In addition to reviewing the biologic basis, high success rate, and advantages of tooth autotransplantation, this article introduces a naming convention for transplanted teeth.

Background: Although wisdom-tooth extraction is a routine intervention, the postoperative period remains marked by local inflammation classically manifesting as pain, edema and trismus. Furthermore, there is no consensus on the best operative techniques, particularly for the mucosal closure stage on impacted mandibular wisdom teeth., Methods: This parallel, randomized, non-blinded study compared pain following removal of impacted third molars, with and without sutures. Patients were electronically allocated 1:1 to extraction with versus without sutures. Patients ≥ 14 years' old scheduled for extraction of four impacted wisdom teeth under general anesthesia at three French hospitals were eligible for inclusion. Exclusion criteria included taking antiplatelet agents or anticoagulants, coagulation disorders or immunosuppression, and planned orofacial surgical procedures or emergency pain/infection. The primary objective was pain evaluated by Visual Analogue Scale on Day 3. Secondary outcomes were edema, trismus, healing, complications, painkiller consumption and quality of life on Day 3 and 31., Results: Between June 2016 and November 2018, 100 patients were randomized. Finally, 44 patients in the Suture group and 50 patients in the Without Suture group were analyzed. Mean age was 16.5 years and 66.6% of patients were female. After adjustment on center, age and smoking, no statistical difference was seen between groups for pain on Day 3 (p = 0.904). No differences were seen for swelling, trismus, consumption of painkillers, healing, complications or quality of life. Smokers had a 3.65 times higher complications rate (p = 0.0244)., Conclusions: Sutureless removal of third molars is thus a reliable technique without negative consequence on outcomes, and allows shorter operating time. Smoking is a risk factor for postoperative complications. Trial registration www., Clinicaltrials: gov (NCT02583997), registered 22/10/2015., (© 2022. The Author(s).)

Objective: The aim of this study was to assess the relation between radiographic findings in large field of view (FOV) cone beam computed tomography (CBCT) exams and clinical findings of mandibular third molars in relation to the pre-operative patient information., Material and Methods: Two hundred and nine mandibular third molars in 134 orthognathic patients examined with CBCT were removed. Three observers assessed tooth- and mandibular canal-related variables in CBCT images, and the findings were correlated to clinical findings during surgery for all observers: tooth angulation, number and morphology of roots and close relationship between the tooth and the mandibular canal. Moreover, positive (PPV) and negative (NPV) predictive values and positive (LR+) and negative (LR-) likelihood ratios were calculated for the canal-related variables. Inter- and intra-observer reproducibility was expressed as percentage accordance and kappa-statistics., Results: Generally, there was high correlation between radiographic and clinical tooth-related variables. The opposite was true for the canal-related variables, since the PPV and LR + were low. The highest PPV and LR + were found when the mandibular canal was positioned between the roots of the third molar., Conclusions: Tooth-related findings in CBCT are reliable, whereas mandibular canal-related findings should not affect the information provided to the patient pre-operatively.

Introduction: Third molars are common teeth to be impacted. The position of mandibular third molar is such that it is in close contact with inferior alveolar canal which may lead to nerve damage during its removal. So, this study was conducted to find out the prevalence of compression of inferior alveolar canal by mandibular third molars., Methods: This descriptive cross-sectional study was conducted on images collected from Dental Imaging Centers of Nepal from 25th June 2020 to 15th February 2021 after obtaining ethical clearance from Nepal Health Research Council (Reference number: 2100). A convenience sampling method was used to collect 433 cone-beam computed tomography images showing the relation between the third molars and inferior alveolar canal. Data were analyzed using the Statistical Package for the Social Sciences version 16. Point estimate at 95% confidence interval was calculated along with frequency and proportion for the binary data., Results: Out of 433 images, 135 (31.17%) (26.80-35.53 at 95% Confidence Interval) images showed compression of inferior alveolar nerve by mandibular third molar. The study result indicated that 16 (11.85%) buccally placed, 50 (37.03%) lingually placed and 69 (51.11%) inferiorly placed inferior alveolar canal were compressed by apices of mandibular third molars., Conclusions: The prevalence of compression of inferior alveolar canal by mandibular third molar was found to be similar to other studies done in similar settings. Compression of the canal was more evident when inferior alveolar canal is situated lingually.

Background: The main objective of this systematic review was to collect the pre-existing scales for assessing the difficulty of third molar extraction. The secondary objective was to design a proposal for a preoperative evaluation protocol for the difficulty of third molar extraction., Material and Methods: Two independent researchers conducted an electronic search in Pubmed (MEDLINE), Cochrane, and Scopus databases during March 2021. Included studies evaluated the prediction of the difficulty of surgical removal of impacted upper or lower third molars using new indices/scales or pre-existing scales with or without modifications. Articles referring to coronectomies or assessing pre-surgical difficulty using other tools were excluded. Neither language nor publication date restrictions were applied., Results: Out of 242 articles, 13 prospective cohort studies were finally selected. Seven developed new indices/scales, and 6 assessed the predictive ability of some pre-existing scales. Most of the indices/scales contained radiological variables and few added any patient-related variables. We proposed a preoperative assessment protocol of the difficulty of third molar extraction to facilitate treatment planning and/or considerate referral in cases of high difficulty. This proposal used patient-related, radiological and surgical variables., Conclusions: Using a preoperative protocol to evaluate the surgical difficulty, including different patient-specific, radiological and surgical variables, could facilitate treatment planning, help clinicians prevent complications and assess the possibility of referral.

In scientific fields, various methods of statistical analysis such as bibliometric analysis have been used to determine the effectiveness of journals, research, and articles. The aim of this study was to conduct a bibliometric analysis to systematically and understandably characterise publications on impacted third molar surgery (ITMS) from 2000 to 2020. The articles were retrieved on the same day (1 January 2021) from the Web of Science Core Collection (WoSCC) database of the Web of Science to prevent bias due to daily updates of the databases. A total of 3326 publications from 2000 to 2020 were analysed. The United States of America (USA) had the highest number of publications and h-index value. The highest number of co-citations were of Pell GJ. ITMS research was collected under nine 'clusters'. In this study, developments, the most influential publications, journals, and countries in the research of ITMS were determined based on the evidence gained through bibliometric analysis., (Copyright © 2021 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Ankylosis of a molar during active growth leads to a significant vertical bone defect, extrusion of the opposing molar, and inclination of adjacent teeth. Treatment timing is an essential factor for the patient's quality of life. Early extraction of the ankylosed molar and protraction of the second molar is challenging because of the difficulty of tooth movement and the uncertainty of the normal eruption of the third molar. In view of the uncertainty of eruption of the mandibular third molar, it is essential to assess the potential for eruption according to the developmental stage of the third molar and to secure sufficient space for eruption. In this case report, a girl with an ankylosed right mandibular first molar and an advanced vertical bone defect was treated via early extraction of the ankylosed molar along with the intrusion of the maxillary molar and mesial root movement of the second molar before the initiation of third molar root formation. Restoration of the vertical bone defect was noted at the end of treatment. In addition, spontaneous eruption of the third molar was observed, which was in contrast to the mesioangular impaction of the contralateral third molar. This case emphasizes the importance of treatment timing to increase the chance of utilization of the third molar., (© 2021 by The EH Angle Education and Research Foundation, Inc.)

Third molar surgery is the most common ambulatory procedure done by oral and maxillofacial surgeons. Surgical approaches for the removal of third molars have been published since the 20th century. This article reviews the history and development of extraction techniques through a literature review. The literature was selected through a search of an electronic database. Key words for the Medline search were "mandibular/maxillary third molar," "impacted mandibular/maxillary third molar," "mandibular/maxillary third molar flap design," and "mandibular/maxillary third molar incision." The search was restricted to English-language articles. Additionally, a manual search in the major oral surgery journals and books was performed. The aim of this article is to examine the evolution of third molar surgery, recognize pioneering techniques, and compare these techniques to current approaches. Common approaches employed today are discussed and treatment philosophies with thoughts for future therapies are provided., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to apply concentrated growth factor (CGF) to the transplanted area with inflammation, to observe the clinical effects of CGF on the inflammation area assisted by 3D printing technology., Methods: A total of 52 compromised mandibular first or second molar with chronic periapical lesions were transplanted with mature third molars. The patients were divided into CGF group (n = 26) and control group (n = 26) and transplanted into fresh extraction sockets with or without CGF. All the patients underwent clinical and radiographic examinations during the follow-up., Results: Average surgery and extra-oral time were 39 min (± 7.8) and 42 s (± 10.2). The success rates of CGF group and control group were 100% and 92.3% respectively. Most of the periapical lesions in CGF group healed completely within 3 months, which was significantly faster than control group. The initial stability of CGF group was better than control group immediately after operation, and the degree of pain in CGF group was lower than control group on the 1st and 3rd day after operation., Conclusions: The application of CGF in recipient site with chronic periapical lesions can accelerate the regeneration of alveolar bone and the healing of inflammation, greatly shorten the healing period. Meanwhile, CGF help to reduce postoperative pain and reaction at the early stage of healing and increase the success rate of autogenous tooth transplantation (ATT). Additionally, the use of 3D printing model can greatly reduce the extra-oral time of donor teeth., (© 2021. The Author(s).)

Objective: The purpose of this study was to evaluate whether Kinesio taping (KT) can improve patient discomfort after mandibular third molar surgery., Materials and Methods: This systematic review and meta-analysis was conducted according to the PICO strategy. We searched 4 databases for related articles. All controlled trials or randomized controlled trials that evaluated the application of KT after mandibular third molar surgery were included. Screening and article selection were carried out by two independent reviewers. The main evaluation indicators were facial swelling, pain, and trismus. All statistical analyses were conducted using Review Manager 5.3 software., Result: This analysis included 8 articles. The combined results showed that compared with the control group, the postoperative application of KT significantly reduced pain in the early (early stage mean difference (MD), - 2.00; 95% confidence interval (CI), - 2.40 to - 1.60; P < 0.00001) and late (late stage MD, - 1.18; 95% CI, - 2.26 to - 0.11; P = 0.03) postoperative periods and, thus, reduced the intake of painkillers. KT also reduced facial swelling in the early and late postoperative periods (early stage standardized mean difference (SMD), - 1.34; 95% CI, - 1.99 to - 0.68; P < 0.0001; late stage SMD, - 0.31; 95% CI, - 0.51 to - 0.11; P = 0.002). In addition, the postoperative application of KT improved restricted mouth opening in the early and late postoperative periods (early stage MD, - 5.03 mm; 95% CI, - 6.32 to - 3.74 mm; P < 0.00001; late stage MD, - 3.42 mm; 95% CI, - 5.31 to - 1.52 mm; P = 0.0004)., Conclusion: KT can significantly reduce postoperative pain, swelling, and trismus after impacted mandibular tooth extraction. Additional high-quality and rigorously designed randomized controlled trials should be conducted to verify these conclusions., Clinical Relevance: KT is a low-cost, simple, effective nondrug therapy for the postoperative management of mandibular third molar extraction and has broad prospects for clinical application., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To develop a novel classification making full use of radiographic three-dimensional (3D) information to describe the position, geometric configuration of a mandibular third molar (M3M) and its spatial relation to neighboring structures such as the mandibular canal (MC). The classification presented in this study helps to establish a common language and serves as a framework for further studies, for example, on 3D parameters influencing prognosis of the M3M and level of difficulty associated with its removal., Material and Methods: A total of 8 parameters were included in the classification including position, the cranio-caudal height, the number of roots of the M3M as well as its spatial relationship to the MC, its course, its deformation, and distance to the M3M. The classification was retrospectively applied to a sample of 483 patients and these data were statistically evaluated., Results: The most commonly observed categories were the (+) vertical position (39.8%); the cranio-caudal height A (38.7%); 2 roots (83.2%); and the spatial relationship no contact caudal (37.5%). Contact between the M3M and inferior alveolar nerve was observed in 58% of all cases. A deformation of the MC was found in 81% of cases., Conclusions: Our novel classification aims to provide a more holistic description of parameters defining 3D M3M position, as well as its spatial relation to relevant neighboring structures. It creates a uniform terminology that can be applied in practice by surgeons and radiologists, and also serves as a foundation for further research projects, such that results from similarly designed studies could be compared., (Copyright © 2021 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: This study aimed to evaluate the anti-inflammatory effect of oral dexamethasone 4 mg in a single dose preemptively administered to reduce pain, swelling, and trismus following mandibular third molar surgeries., Methods: A split-mouth randomized clinical trial was performed including 22 participants undergoing surgical removal of bilateral and symmetrically positioned third molars. A total of 44 teeth were allocated by simple randomization to either the test or nonintervention/control side. Oral dexamethasone 4 mg was administered on the test side an hour before the surgery. All of the participants were unaware of the medication studied, and only 1 surgeon, blinded to the medication intake, performed all of the procedures. Anti-inflammatory effect was evaluated using the clinical parameters of mouth opening, swelling, and rescue analgesic medication intake to control pain. The statistical analysis was blinded to the allocation groups, and a significance value P < .05 was adopted for all the tests., Results: Dexamethasone reduced the mean of rescue analgesic medication intake by 5 times (P = .002). Facial swelling was lower on the test side by 72h postsurgery in comparison with the control side (P = .036). No significant difference in mouth opening was found between the groups., Conclusions: Preemptive use of oral dexamethasone 4 mg proved to be effective in controlling pain and reducing the need for rescue medication and had a beneficial effect in reducing swelling during a short postoperative period., (Copyright © 2021 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Data sources The review carried out electronic searches using several online databases through November 2018, namely PubMed, Virtual Health Library, Cochrane Library and Scopus. Terms searched for on these databases included third molar, flap and variations thereof. A grey literature search was also conducted.Study selection In total, 2,455 articles were identified,1,449 being duplicates. Additionally, 1,006 articles remained for assessment which, with clear exclusion criteria listed, was reduced to 20. From the 20 incorporated into the review, 18 articles were utilised for meta-analysis. Three of the researchers were involved in assessing the articles after research management software was used to remove the aforementioned duplicates. A Cohen's kappa index was calculated to confirm inter-rater consistency using 10% of the articles.Data extraction and synthesis Data extraction followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidance.Results From their systematic review and meta-analyses, the authors found that flap design had no effect on common post-operative complications including pain, trismus, dehiscence, or osteitis. The triangular flap did, however, have greater post-operative ecchymosis but reduced periodontal probing depth on day seven when compared to the envelope flap in mandibular third molar surgeries.Conclusions Third molar surgery is carried out across all facets of dentistry, including general and specialised. Further studies must be carried out that look specifically at these variables utilising randomised controlled trials so a consensus can be achieved across the profession of which flap is of superior design., (© 2021. British Dental Association.)

Purpose: The purpose was to determine the effect of watching an informative video about mandibular third molar (M3M) removal on patient anxiety and hemodynamic parameters., Patients and Methods: A randomized controlled clinical trial was carried out in healthy patients (aged between 18 and 40 years) requiring M3M extraction under local anesthesia. Patients with previous tooth extractions, psychiatric disorders, or cardiac problems or patients undergoing anxiolytic or antidepressant drug treatment were excluded. Participants were randomized into 2 groups according to whether they watched an informative video about the surgical procedure (video group) or not (control group). The primary outcome variable was the difference between groups regarding patient anxiety assessed with the State-Trait Anxiety Inventory (STAI) and the Modified Dental Anxiety Scale (MDAS). The secondary outcome variables were hemodynamic parameters recorded during different moments of the surgical procedure. Descriptive, bivariate, and multivariate analyses were performed, and a repeated-measures mixed model was generated. Statistical significance was considered for P < .05., Results: Fifty patients referred for M3M extraction met the inclusion criteria. The final data analysis was based on 47 patients: 25 from the video group and 22 controls. The bivariate analysis showed the video group to have a significant decrease in anxiety as measured by the MDAS (P = .006; 95% confidence interval [CI], -4.1 to -0.7) and STAI-State (P = .003; 95% CI, -13.7 to -0.7). A significantly lower heart rate was likewise found in the video group (χ 2  = 4.30, df = 1, P = .038). The linear regression analysis adjusting for the STAI-Trait also showed lower dental anxiety measured by the MDAS in the video group (P = .023; 95% CI, 0.32 to 4.14)., Conclusions: Providing preoperative information through an informative video about M3M removal significantly reduces patient anxiety and heart rate during the surgical procedure., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to predict the risk of lingual plate fracture during mandibular third molar (M3) extraction., Materials and Methods: Cone beam computed tomography (CBCT) data from 264 mandibular M3s (erupted and impacted) from 264 patients (104 males and 160 females; age range, 17-75 years) were retrospectively analyzed. Lingual plate thicknesses at the levels of the mid-root and root apex of the M3s were measured and defined as "thicker" (bone thicker than 1 mm), "thinner" (bone thinner than 1 mm), or "perforated" (bone perforated by the M3 root). These measurements were correlated with potential risk factors for thinner and perforated lingual plates: tooth position of the mandibular M3, morphology of the lingual plate, and patient characteristics (age and sex)., Results: The mean thickness of the lingual plate was 1.49 ± 1.38 mm at the mid-root of the M3s, and 2.35 ± 2.03 mm at the root apex. Multivariate regression analyses revealed that mesioangularly and horizontally impacted M3s were significantly associated with thinner and perforated lingual plates at the mid-root (P < 0.001), whereas the M3s in infra-occlusion positions (in infra-occlusion when compared with the adjacent second molar) had thinner lingual bone at the root apex (P = 0.022 and P = 0.027, depending on the level of impaction). Female patients were less likely to have lingual plate perforation (P = 0.036)., Conclusions: Mesioangulation, infra-occlusion, and male sex were risk factors for lingual plate fracture., Clinical Relevance: When the risk of lingual plate fracture is high, a sufficiently large flap, osteotomy, and tooth section by bur or piezosurgery are recommended to create a good operative field and avoid excessive pressure on the lingual plate.

Background: The periodontal healing distal to the mandibular second molar (M2M) after coronectomy of the M3M has shown controversial results. We aimed to combine a digital method with cone-beam computed tomography (CBCT) and estimate periodontal healing of M2M after M3M coronectomy. An accurate and stable indicator in three dimensions was also explored tentatively., Methods: Patients with a M3M in contact with the inferior alveolar canal were included. CBCT was applied immediately after coronectomy (baseline) and 6-months later. Data were investigated with digital software for registration. Previously reported and coronectomy-related factors were included for univariate and multivariate analyses., Results: A total of 181 patients (213 M3Ms) completed 6-month follow-up. Significant reduction in the distal intra-bony defect (DBD) depth of the M2M was shown (1.28 ± 1.24 mm, P < 0.001). DBD depth of the M2M at baseline was the most influential factor (r = 0.59), followed by preoperative M3M condition, age, rotation and migration of the root complex. Remaining enamel (OR = 6.93) and small retromolar space (0.67) contributed to re-contact of the root complex and M2M. Bone volume regenerated in the distal 2 mm was associated significantly with DBD-depth reduction (r = 0.74, P < 0.001)., Conclusions: Bone volume regenerated in the distal 2 mm of the M2M denoted stability of distal periodontal healing of the M2M. DBD depth at baseline was the most influential factor for healing of a DBD of the M2M after M3M coronectomy. The remaining enamel and a small retromolar space could contribute to re-contact of the root complex and the M2M., Trial Registration: China Clinical Trial Center, ChiCTR1800014862 . Registered 10 February 2018.

The aim of this study was to investigate the clinical effect of the extraction of low horizontally impacted mandibular third molars by three-piece tooth sectioning. Sixty patients with low horizontally and buccally-impacted mandibular third molars on both sides were operated on under local anaesthesia. Three-piece tooth sectioning was used on one side (n=60) and the molars were extracted using a high-frequency electric knife, 45° reversed-angle high-speed turbine, and special long crank drill. Each molar was cut into three pieces, which were removed in the following order: middle, root, and crown. One month later, the molars on the other side of each patient's jaw were removed by conventional extraction (n=60) with the same equipment. The crown was cut and removed first, and then the remaining piece was extracted. The duration of the procedure, and incidence postoperative swelling, pain, and trismus were compared between the two groups. The procedure was shorter with the three-piece method (10.05 (0.51) min) than with the conventional method (20.15 (0.88) min, p<0.01). Postoperative swelling, pain, and trismus were all less severe with the three-piece method than with the conventional method (p<0.01). Three-piece tooth sectioning could be used to remove low horizontally and buccally-impacted mandibular third molars, as it can shorten the duration of the procedure, reduce trauma, and reduce the incidence of postoperative complications., (Copyright © 2020 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Objective: To analyze the prevalence of distal caries in mandibular second molars (M2Ms) and its correlation with the three-dimensional position of mandibular third molars (M3Ms) by cone beam computed tomography (CBCT) images., Materials and Methods: CBCT scans involving 421 M3Ms were assessed. The presence of distal caries of M2Ms, patient age and gender, impaction depths and mesial angulation of M3Ms, the cementoenamel junction (CEJ) distances and contact point localization, and the horizontal positions of M3Ms were assessed. Risk factors were identified by multivariate logistic regression analysis., Results: The overall prevalence of distal caries in M2Ms was 31.6%. Mesial angulation (16°-75°) of M3Ms, contact point localization at or below the CEJ of M2Ms, and a buccal or lingual position of M3Ms relative to the molar line were identified as risk factors for the prevalence of distal caries in M2Ms (p < 0.05). Distal caries was more severe when the mesial angulation of M3Ms was 16°-75° (p < 0.05)., Conclusions: Buccal or lingual position of M3Ms may represent a new risk factor for the distal caries in M2Ms. Mesial angulation (16°-75°) of M3Ms is a predictive parameter for both the presence and severity of distal caries in M2Ms., Clinical Relevance: As the presence of distal caries in M2Ms is significantly associated with the three-dimensional position of M3Ms, watchful monitoring or prophylactic removal of M3Ms should be deliberated when M3Ms are mesially angulated (16°-75°), buccally or lingually positioned, and with the contact point localization at or below the CEJ of M2Ms.

Background: The extraction of third molars is one of the most common procedures in oral and maxillofacial surgery clinic. Surgical extraction involves the manipulation of both soft and hard tissues, so the patient usually experiences pain, swelling, and trismus in the immediate post-operative period. Several studies have been conducted using different types of surgical flaps to provide access with the least possible damage of soft tissues. Designing and implementing an optimum flap, which provides easier technique, better visibility, minimal post-operative complications, and best healing, is an aspired goal of every oral surgeon. This study aimed to compare lingual-based four-cornered flap with conventional triangular flap, and to evaluate its effect on post-operative pain after surgical extraction of impacted lower third molars., Material and Methods: Seventeen patients (age ranged from 19 to 26 years) with bilateral, symmetrical impacted lower third molars (n=34) were included in the study. This was a randomized clinical trial with a split-mouth design. The impacted molars were assigned randomly, by coin flipping, to two groups: Case side with lingual-based four-cornered flap (Group A), and control side with conventional triangular flap (Group B). Away from the incision, the prognosis, surgical intervention, and postoperative procedures were exactly the same for the two groups. Postsurgical pain was assessed for 5 days using visual analogue scale (VAS) and by recording patients need for analgesics on a daily basis. Patients were also evaluated via a self-reporting questionnaire, i.e. Postoperative Symptoms Severity (PoSSe) scale, administered on the seventh postoperative day., Results: Pain scores recorded in Group A were found to be significantly lower as compared to pain scores in Group B in the 5 postoperative days (P<0.05). Total analgesic intake in Group B was significantly higher (P<0.05). PoSSe scores were lower in Group A, however, this difference was insignificant (P>0.05)., Conclusions: According to the data of the current study and within its limits, it appeared that lingual-based four-cornered flap design was superior to the conventional triangular flap regarding the postsurgical discomfort and pain.

An impacted third molar is one of the most common dental abnormalities. Among the reasons for impaction the most common are: insufficient space, time of eruption, improper position of the tooth bud, and genetic disruptions. To investigate if runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2), and msh homeobox 1 (MSX1) are differently expressed depending on the position of the molar, we studied 32 patients who had been referred for surgical removal. An orthopantomogram was used to separate them according to Winter's, and Pell & Gregory's, classifications. Bone samples were harvested during the operation for gene expression assay. The Kruskal-Wallis, Dunn's post hoc, and Spearman's correlation, tests were used to assess the significance of differences. No correlations were found in expression of the genes, and no differences between expression in maxillary and mandibular third molars, nor were they expressed differently according to Winter's or Pell and Gregory's classifications or in relation to impaction of the mandibular ramus. However, MSX1 was expressed differently when account was taken of the depth of impaction in maxillary third molars (p = 0.029), but there was no difference in expression of RUNX2, BMP2, and MSX1 for the Pell and Gregory classification of depth of impaction (p > 0.05). We conclude that MSX1 is expressed differently depending on the depth of maxillary impaction phenotypes., (Copyright © 2020 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim of the present study was to evaluate the genetic and environmental factors influencing the localization of mandibular third molars by analyzing the panoramic radiographs of twins. We examined the mandibular third molars of Japanese monozygotic (MZ) and dizygotic (DZ) twins recruited by the Osaka University Center for Twin Research., Materials and Methods: The present study included 49 pairs (98 participants) of MZ twins and 11 pairs (22 participants) of DZ twins. Using panoramic radiography, we evaluated the degree of eruption of mandibular third molars according to the height of the alveolus bone and the third molar space/crown width ratio. Using co-twin control analysis and a generalized linear mixed model, we evaluated the effects of various factors, including gender, age, body height, number of teeth, length of the lower dental arch, existence of a second molar, bruxism, and previous orthodontic therapy., Results: Body height, third molar space/crown width ratio, and length of the mandibular dental arch were related to the degree of mandibular third molar eruption and were strongly influenced by genetic factors rather than common or unique environmental factors., Conclusions: The degree of third molar eruption was more similar among MZ twins than among DZ twins; therefore, genetic factors can be expected to have more significant influence than will environmental factors. These results can help identify the trend of third molar eruption from a young age, allowing us to advise the early extraction of mandibular third molars for patients with a short stature, narrow retromolar space, or short mandibular dental arch. In addition, if the genes that influence the degree of eruption were identified, we would be better equipped to predict an individual's risk of impaction, and indications for extraction might change., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: We aimed to investigate whether cone-beam computed tomography (CBCT) alters the treatment decision for impacted mandibular third molar (M3M) surgery when the third molars show proximity to the inferior alveolar canal (IAC) on panoramic radiography (OPG) and to examine surgeons' confidence in the various treatment options., Methods: We performed a retrospective study evaluating a series of randomized OPG and CBCT images and answering a set of questions regarding impacted M3Ms. The anatomic risk factors studied included the proximity of M3M roots to the IAC, vertical relationship between the M3M and the IAC, and interruption of the IAC cortex by M3M roots. The primary outcome variable was the treatment decision of whether to observe, extract under local anesthesia, extract under general anesthesia, or perform coronectomy. The secondary outcome variable was confidence in the proposed treatment plan. The χ 2 test was used to compare proportions and to test the differences in the treatment plan according to the studied independent variables. Binary logistic regression was used to determine the effect of anatomic factors. P < .05 was considered statistically significant., Results: The study sample consisted of 132 impacted M3Ms in 71 patients. No significant differences in the proposed treatment plan were found when the imaging modalities (OPG and CBCT) were compared (P > .05). Examination of CBCT enabled detection of anatomic risk factors (P < .001). Binary logistic regression showed the absence of IAC cortex interruption to be the most significant determinant toward planning for extraction on OPG (odds ratio, 3.1; P < .005) and on CBCT (odds ratio, 5.0; P < .001). Surgeons were more confident when planning for extraction (P < .001)., Conclusions: The use of CBCT provides a better understanding of the anatomic relationship between M3M roots and the IAC. However, experienced surgeons dealing with impacted M3Ms with evidence of proximity to the IAC on OPG can decide on the treatment modality without CBCT., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Three adult patients, ages 28 (female), 36 (male) and 53 (male), respectively, were referred by their dentists to an orofacial surgeon concerning problems with their third molars. With the woman, teeth 38 and 48 were removed. After the removal of tooth 38, a permanent periodontal attachment loss of the adjoining second molar occurred. With the second patient, retention of tooth 48 caused serious damage to the adjoining second molar, resulting in the loss of the tooth. At the time of removal, there was a question of increased risk of inflammatory complications and nerve damage. With the third patient, removal of his impacted tooth 38 led to osteomyelitis and a fracture of the angle of the mandible. According to the newly published 'Third molar' in the Dutch Clinical Guidelines, the advice is to consider the removal of asymptomatic third molars in 17-year-old patients. In the case of impacted third molars with mesial or horizontal angulation and partial eruption, the risk of pathology is such that preventive removal is advised. An intraoral radiograph (periapical or bitewing) as a first screening is recommended here.

Purpose: The aim of this study was to investigate the treatment decisions of oral-maxillofacial surgeons in the management of impacted lower third molars (M3s) according to panoramic radiography (PR) and cone beam computed tomography (CBCT) risk analysis., Patients and Methods: Ten surgeons analyzed 40 deliberately selected M3 cases showing 1 or more panoramic high-risk signs: 1) darkening of the root, 2) interruption of the white line, 3) diversion of the inferior alveolar canal (IAC), 4) narrowing of the IAC, and 5) 2 or more signs occurring simultaneously (including darkening and/or interruption of the IAC). After evaluating the PR images, the observers analyzed the patients' CBCT images. The treatment decision (extraction vs coronectomy) and surgical technique (number of planned tooth sections) were recorded., Results: On the CBCT coronal slices, direct contact between the M3 and IAC, together with narrowing and/or fenestration of the IAC, was observed most frequently when 2 or more panoramic signs were seen simultaneously on the PR images (odds ratio [OR], 7.2; P = .021). CBCT findings led to a significant decrease in the number of coronectomy decisions (23% vs 14.5%, P = .002), which was most prominent in the groups showing panoramic signs of darkening (approximately 50%, P = .007) and narrowing (approximately 66%, P = .044). A significant number of extraction decisions were modified to coronectomy when 2 or more panoramic signs occurred together (OR, 7.9; P < .001). However, there were no significant differences regarding the number of planned hypothetical tooth sections., Conclusions: The results showed that the surgeons' confidence in the treatment decision increased after CBCT imaging, resulting in fewer coronectomy decisions. CBCT information that changed a previous coronectomy decision to extraction was most frequently observed in cases showing darkening and narrowing PR signs. The chance of changing an extraction decision to a coronectomy decision after evaluating the patient's CBCT images was the highest when 2 or more PR signs were observed simultaneously., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis., Methods: A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test., Results: The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05)., Conclusions: The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

Objectives: The aim of the study was to examine the prevalence of third molars in panoramic radiographs in a population-based study of adults aged ≥30 years., Methods: Out of a sample of 8028 inhabitants of Finland, selected with two-staged stratified cluster-sampling method for the Health 2000 Survey, 5989 participated in clinical oral examination and panoramic radiography. Mean age was 52.5 years (SD 14.6; range 30-97 years). The following variables were included in the analysis: participant characteristics, clinical number of all teeth, and radiographic prevalence and characteristics of third molars. Statistics included chi-squared, Fisher's exact, and Kruskal-Wallis tests and SAS-SUDAAN calculations., Results: A total of 5912 third molars in 47.8% of the study population were recorded from panoramic radiographs. At least one impacted third molar was found in 21.9% of the study population. More than half (57.3%) of the remaining third molars were located in the mandible. A preponderance of participants with all third molars missing were observed in the oldest age group, women, those with lower education and those living in the countryside. Third molars or remnants thereof were observed radiographically in 3.9% of clinically edentulous study population., Conclusions: The panoramic radiographs disclosed many remaining third molars in adult Finns aged ≥30 years. One-third of the third molars located impacted which may cause unexpected need for care., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The primary goal of this study was to identify and quantify indications for retaining third molars. This retrospective cohort study included 1682 patients (818 male, 864 female; mean age 31 years) who were referred to the University Hospitals Leuven for third molar removal. Eight reasons for retaining the third molars were identified: (1) risk of damaging adjacent structures, (2) compromised health status, (3) adequate space for eruption, (4) third molar serves as abutment tooth, (5) orthodontic reasons, (6) eruption into proper occlusion, (7) symptomless third molars in patients >30 years old, and (8) patient preference. To compare these categories between sex and age groups, a generalized linear model for binary data was fitted with a logit link. A total of 1149 third molars in 548 patients were not extracted. The most frequent reasons for retaining third molar teeth were: eruption into proper occlusion (31.9%), patient preference (31.5%), and symptomless third molars in patients >30 years old (17.5%). Compromised health status and advanced age were often included in the decision regarding whether to retain the third molars. One third of the referred patients had reasons to retain one or more third molars. These findings might facilitate the future development of a consensus statement., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The aim of this systematic review was to determine the patient, radiological, and operative variables associated with surgical difficulty in the extraction of third molars, according to a visual analogue scale completed by the surgeon, operative time, or surgical technique. Searches of the PubMed (MEDLINE), Scopus, and Cochrane Library databases were conducted by two independent reviewers. Randomized and non-randomized clinical trials and prospective cohort studies evaluating surgical difficulty in the extraction of impacted mandibular or maxillary third molars according to patient, radiological, and operative variables were included. The full texts of 21 of the 859 articles initially retrieved were analysed, and 15 articles were included in the final systematic review. All 15 reported prospective cohort studies. The following variables were found to be on the spectrum of highly difficult or complex cases: older patient age and being overweight (patient variables), surgeons with little experience and the use of complex surgical techniques requiring tooth sectioning linked to hard tissue impaction (operative variables), and adverse radiological factors such as deep impaction, unfavourable angulation and root morphology, and a close relationship with the second molar, maxillary sinus, or the inferior alveolar nerve canal (radiological variables)., (Copyright © 2019 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Background: Deciding whether or not to extract third molars remains a controversial situation in dental practice. Image exams support this decision by enabling a close view of the third molar, its adjacent bone and its relationship with the second molar. This study aimed to assess and compare second molar bone loss adjacent to impacted mandibular third molar in panoramic radiographs (PAN) and cone beam computed tomography (CBCT) scans., Material and Methods: A sample of 70 patients was selected (n=124 teeth). Each patient had a set of a panoramic radiograph and CBCT scans consecutively taken for dental treatment purposes. In PAN and CBCT, mandibular third molars were classified based on their position and bone loss of the adjacent second molar. Agreement between PAN and CBCT scans was assessed and quantified., Results: Outcomes of bone loss assessment were different between PAN and CBCT scans (p<0.05). Bone loss was found in 62.9% of the PAN, while in CBCT scans it was found in 80%. In particular, nearly 29% (n=27) of the teeth that were classified without bone loss in PAN were classified with bone loss in CBCT scans. Mesioangular and horizontal third molars had a statistically significant association with bone loss of the adjacent second molars (p<0.05). In general, PAN underestimated the severity of bone loss compared to CBCT scans (p<0.05)., Conclusions: Diagnosing second molar bone loss due to impaction of adjacent third molar in PAN may be challenging because of false negatives. Impacted third molars justify preoperative CBCT scans if second molar bone loss needs to be precisely assessed for a more detailed and reliable treatment plan.

Purpose: Dental anxiety about extraction of impacted mandibular third molars changes the activity of the autonomic nervous system. Thus, to provide safe dental treatment, it is important that a surgeon be aware of a patient's pretreatment anxiety and autonomic nervous system state. Therefore, we analyzed how a scheduled treatment to extract mandibular third molars affects the pretreatment electroencephalogram (EEG), autonomic nervous system, and psychological state of patients. We compared their findings with those of volunteers not scheduled to undergo dental treatment., Patients and Methods: The study enrolled 30 patients who were scheduled to undergo impacted mandibular third molar extraction (ie, pretreatment group) and 30 volunteers who were not (ie, control group). Heart rate variability and an EEG were recorded during the experiment. The State Anxiety Inventory-State Anxiety scale (STAI-S) scores were recorded before the procedure. For the statistical analysis, P < .05 was deemed statistically significant., Results: High-frequency (HF) variability was significantly decreased and the STAI-S score was significantly increased in the pretreatment group compared with the control group (P < .01 for both). The low frequency (LF)/HF ratio and alpha-wave activity showed a significant negative correlation on both sides in the control group (P < .01); however, no correlation existed in the pretreatment group. The LF/HF ratio and STAI-S score showed a significant positive correlation in the pretreatment group (P < .05); however, no correlation existed in the control group., Conclusions: Predicting a patient's autonomic nervous system state before dental treatment based on the EEG was difficult. The STAI-S psychological test was a useful method., (Copyright © 2019 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Objectives: To assess: (1) the workflow in the treatment decision process of mandibular third molars based on a panoramic image and CBCT and (2) the impact of radiographic markers in CBCT on the decision to perform coronectomy., Methods: 1437 teeth in 917 patients (mean age 27.8 years, range 18-72) underwent clinical and panoramic examination. If there was an indication for removal of the tooth, and signs of a close relation to the inferior alveolar nerve were present in the panoramic image, a CBCT was performed. Treatment decision based on panoramic image and CBCT was calculated. Statistical analyses were performed to assess whether signs in CBCT had an impact on the treatment decision "coronectomy". Moreover, the actually operated teeth and post-operative sensory disturbances were assessed and discussed in relation to the radiographic method., Results: Based on the panoramic image, in 462 cases it was decided not to treat, 553 were scheduled for surgery, and 422 referred for a CBCT examination. "No bony separation between the tooth and mandibular canal" seen in CBCT was the main factor influencing the decision to perform a coronectomy (odds ratio = 56.8, p < 0.001). 840 mandibular third molars had undergone surgical intervention, 152 had a coronectomy and 688 were fully removed. Six patients perceived a sensory disturbance of the inferior alveolar nerve: one permanent and five temporary., Conclusion: 29% of the examined cases were referred for a CBCT and of these, the majority were scheduled for coronectomy based on the sign "no bony separation between the tooth and mandibular canal" seen in CBCT.

Objectives: To investigate factors associated with spontaneous mesialization of impacted third molars after second molar protraction to close the space caused by a missing mandibular first molar (L-6) or retained deciduous mandibular second molars with a missing succedaneous premolar (L-E)., Materials and Methods: Panoramic radiographs of patients treated with mandibular second molar protraction to close the space due to missing L-6 or L-E (14 males, 36 females, mean age = 18.6 ± 4.4 years) were analyzed before treatment (T1) and after second molar protraction (T2). Factors associated with the amount of third molar mesialization were investigated using regression analyses., Results: Mandibular second molars were protracted by 5.1 ± 2.1 mm and 5.8 ± 2.7 mm, measured at the crown and root furcation, respectively. After second molar protraction, third molars showed spontaneous mesialization by 4.3 ± 1.6 mm and 3.8 ± 2.6 mm, measured at the crown and root furcation, respectively. Nolla's stage of the third molar at T1 (B = 0.20, P = .026) and second molar protraction time (B = 0.04, P = .042) were significantly associated with the amount of third molar mesialization., Conclusions: Greater third molar mesialization was observed when Nolla's stage of the third molar was higher before treatment and when the second molar protraction time was longer.