Positional assessment of lower third molar and mandibular canal using explainable artificial intelligence.

OBJECTIVE: The aim of this study is to automatically assess the positional relationship between lower third molars (M3i) and the mandibular canal (MC) based on the panoramic radiograph(s) (PR(s)). MATERIAL AND METHODS: A total of 1444 M3s were manually annotated and labeled on 863 PRs as a reference. A deep-learning approach, based on MobileNet-V2 combination with a skeletonization algorithm and a signed distance method, was trained and validated on 733 PRs with 1227 M3s to classify the positional relationship between M3i and MC into three categories. Subsequently, the trained algorithm was applied to a test set consisting of 130 PRs (217 M3s). Accuracy, precision, sensitivity, specificity, negative predictive value, and F1-score were calculated. RESULTS: The proposed method achieved a weighted accuracy of 0.951, precision of 0.943, sensitivity of 0.941, specificity of 0.800, negative predictive value of 0.865 and an F1-score of 0.938. CONCLUSION: AI-enhanced assessment of PRs can objectively, accurately, and reproducibly determine the positional relationship between M3i and MC. CLINICAL SIGNIFICANCE: The use of such an explainable AI system can assist clinicians in the intuitive positional assessment of lower third molars and mandibular canals. Further research is required to automatically assess the risk of alveolar nerve injury on panoramic radiographs.

Surgically assisted orthodontic alignment of impacted maxillary canines: A retrospective analysis of functional and esthetic outcomes and risk factors for failure.

INTRODUCTION: The initial position of an impacted maxillary canine might influence the outcome of surgically assisted exposure and orthodontic alignment. Therefore, the purpose of this study was to evaluate existing correlations between the initial position of the maxillary canine and the outcomes of treatment. METHODS: A retrospective cohort study was designed, containing data of 132 patients (47 males, 106 females; median age at the date of surgical exposure 14 ± 4.6 years; range, 10-39 years) with a total of 153 impacted maxillary canines. The sample was based on orthodontic referrals over 4 years at the Department of Oral and Maxillofacial Surgery, Rijnstate Hospital, Arnhem, the Netherlands. The esthetic outcome, treatment duration, and success and failure rate were investigated in relation to the initial position of the maxillary canine as assessed on pretreatment panoramic radiographs (vertical and anteroposterior sector position and angulation of the canine [α-angle]). The esthetic evaluation was performed using the Maxillary Canine Aesthetic Index. The success of treatment was defined as achieving a fully functional eruption of the canine, with an esthetically excellent result, without the need for reinterventions. Failure of treatment was defined as the need for reintervention or removal of the canine. RESULTS: In 96% of the impacted canines, a successful orthodontically assisted eruption was achieved. Age, vertical distance, and angulation are predictors of the esthetic outcome of impacted canines after treatment. Age, bilateral impaction, sector, vertical distance, and angulation are predictors of treatment duration. Age, vertical distance, and buccolingual position are predictors of the need for reintervention. CONCLUSIONS: Pretreatment radiographic variables can help in predicting the outcome and treatment duration of surgically exposed maxillary impacted canines.

Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth.

BACKGROUND: Prophylactic removal of asymptomatic disease-free impacted wisdom teeth is the surgical removal of wisdom teeth in the absence of symptoms and with no evidence of local disease. Impacted wisdom teeth may be associated with pathological changes, such as pericoronitis, root resorption, gum and alveolar bone disease (periodontitis), caries and the development of cysts and tumours. When surgical removal is performed in older people, the risk of postoperative complications, pain and discomfort is increased. Other reasons to justify prophylactic removal of asymptomatic disease-free impacted third molars have included preventing late lower incisor crowding, preventing damage to adjacent structures such as the second molar or the inferior alveolar nerve, in preparation for orthognathic surgery, in preparation for radiotherapy or during procedures to treat people with trauma to the affected area. Removal of asymptomatic disease-free wisdom teeth is a common procedure, and researchers must determine whether evidence supports this practice. This review is an update of an review originally published in 2005 and previously updated in 2012 and 2016. OBJECTIVES: To evaluate the effects of removal compared with retention (conservative management) of asymptomatic disease-free impacted wisdom teeth in adolescents and adults. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 10 May 2019), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2019, Issue 4), MEDLINE Ovid (1946 to 10 May 2019), and Embase Ovid (1980 to 10 May 2019). The US National Institutes of Health Trials Registry (ClinicalTrials.gov)and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. . SELECTION CRITERIA: We included randomised controlled trials (RCTs), with no restriction on length of follow-up, comparing removal (or absence) with retention (or presence) of asymptomatic disease-free impacted wisdom teeth in adolescents or adults. We also considered quasi-RCTs and prospective cohort studies for inclusion if investigators measured outcomes with follow-up of five years or longer. DATA COLLECTION AND ANALYSIS: Eight review authors screened search results and assessed the eligibility of studies for inclusion according to the review inclusion criteria. Eight review authors independently and in duplicate conducted the risk of bias assessments. When information was unclear, we contacted the study authors for additional information. MAIN RESULTS: This review update includes the same two studies that were identified in our previous version of the review: one RCT with a parallel-group design, which was conducted in a dental hospital setting in the United Kingdom, and one prospective cohort study, which was conducted in the private sector in the USA. Primary outcome No eligible studies in this review reported the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth on health-related quality of life Secondary outcomes We found only low- to very low-certainty evidence of the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth for a limited number of secondary outcome measures. One prospective cohort study, reporting data from a subgroup of 416 healthy male participants, aged 24 to 84 years, compared the effects of the absence (previous removal or agenesis) against the presence of asymptomatic disease-free impacted wisdom teeth on periodontitis and caries associated with the distal aspect of the adjacent second molar during a follow-up period of three to over 25 years. Very low-certainty evidence suggests that the presence of asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting the adjacent second molar in the long term. In the same study, which is at serious risk of bias, there is insufficient evidence to demonstrate a difference in caries risk associated with the presence or absence of impacted wisdom teeth. One RCT with 164 randomised and 77 analysed adolescent participants compared the effect of extraction with retention of asymptomatic disease-free impacted wisdom teeth on dimensional changes in the dental arch after five years. Participants (55% female) had previously undergone orthodontic treatment and had 'crowded' wisdom teeth. No evidence from this study, which was at high risk of bias, was found to suggest that removal of asymptomatic disease-free impacted wisdom teeth has a clinically significant effect on dimensional changes in the dental arch. The included studies did not measure any of our other secondary outcomes: costs, other adverse events associated with retention of asymptomatic disease-free impacted wisdom teeth (pericoronitis, root resorption, cyst formation, tumour formation, inflammation/infection) and adverse effects associated with their removal (alveolar osteitis/postoperative infection, nerve injury, damage to adjacent teeth during surgery, bleeding, osteonecrosis related to medication/radiotherapy, inflammation/infection). AUTHORS' CONCLUSIONS: Insufficient evidence is available to determine whether asymptomatic disease-free impacted wisdom teeth should be removed or retained. Although retention of asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting adjacent second molars in the long term, the evidence is very low certainty. Well-designed RCTs investigating long-term and rare effects of retention and removal of asymptomatic disease-free impacted wisdom teeth, in a representative group of individuals, are unlikely to be feasible. In their continuing absence, high quality, long-term prospective cohort studies may provide valuable evidence in the future. Given the current lack of available evidence, patient values should be considered and clinical expertise used to guide shared decision-making with people who have asymptomatic disease-free impacted wisdom teeth. If the decision is made to retain these teeth, clinical assessment at regular intervals to prevent undesirable outcomes is advisable.

The effects of surgically assisted rapid maxillary expansion (SARME) on the dental show and chin projection.

OBJECTIVE: To quantify the postoperative changes of the dental show and chin projection following SARME using 3D CBCT imaging. MATERIAL AND METHODS: 78 patients with transversal maxillary hypoplasia and mandibular hypoplasia who underwent SARME were enrolled into the study. A cone beam computed tomography (CBCT) scan was acquired preoperatively and at least 1 year postoperatively. 3D postoperative changes in the dental show and pogonion position were measured based on soft tissue and hard tissue landmarks. RESULTS: 68 patients (87%) exhibited a postoperative increase in the dental show. The dental show was increased by a mean of 2.2 ± 2.0 mm (p < 0.01). The mean horizontal and vertical displacement of the chin (pogonion) following SARME was 1.6 ± 2.5 mm posteriorly and 1.6 ± 2.0 mm inferiorly (p < 0.01). An inferior displacement of the maxilla and maxillary tooth as well as a consequent clockwise pitch of the mandible seemed to play a role in inducing these postoperative changes. CONCLUSION: An increase in dental show and a posterior and inferior displacement of the chin should be considered prior to SARME to prevent undesirable postoperative changes of the facial esthetics.

Surgical removal versus retention for the management of asymptomatic disease-free impacted wisdom teeth.

BACKGROUND: Prophylactic removal of asymptomatic disease-free impacted wisdom teeth is surgical removal of wisdom teeth in the absence of symptoms and with no evidence of local disease. Impacted wisdom teeth may be associated with pathological changes, such as pericoronitis, root resorption, gum and alveolar bone disease (periodontitis), caries and the development of cysts and tumours. When surgical removal is carried out in older people, the risk of postoperative complications, pain and discomfort is increased. Other reasons to justify prophylactic removal of asymptomatic disease-free impacted third molars have included preventing late lower incisor crowding, preventing damage to adjacent structures such as the second molar or the inferior alveolar nerve, in preparation for orthognathic surgery, in preparation for radiotherapy or during procedures to treat people with trauma to the affected area. Removal of asymptomatic disease-free wisdom teeth is a common procedure, and researchers must determine whether evidence supports this practice. This review is an update of an existing review published in 2012. OBJECTIVES: To evaluate the effects of removal compared with retention (conservative management) of asymptomatic disease-free impacted wisdom teeth in adolescents and adults. SEARCH METHODS: We searched the following electronic databases: Cochrane Oral Health's Trials Register (to 24 May 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 4), MEDLINE Ovid (1946 to 24 May 2016) and Embase Ovid (1980 to 24 May 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing and unpublished studies to 24 May 2016. We imposed no restrictions on language or date of publication in our search of electronic databases. SELECTION CRITERIA: Studies comparing removal (or absence) with retention (or presence) of asymptomatic disease-free impacted wisdom teeth in adolescents or adults. We included randomised controlled trials (RCTs) with no restriction on length of follow-up, if available. We considered quasi-RCTs and prospective cohort studies for inclusion if investigators measured outcomes with follow-up of five years or longer. DATA COLLECTION AND ANALYSIS: Eight review authors screened search results and assessed the eligibility of studies for inclusion according to the review inclusion criteria. Eight review authors independently conducted risk of bias assessments in duplicate. When information was unclear, we contacted study authors for additional information. MAIN RESULTS: This review includes two studies. The previous review included one RCT with a parallel-group design, which was conducted in a dental hospital setting in the United Kingdom; our new search for this update identified one prospective cohort study conducted in the private sector in the USA. Primary outcome No eligible studies in this review reported the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth on health-related quality of life Secondary outcomes We found only low to very low quality evidence of the effects of removal compared with retention of asymptomatic disease-free impacted wisdom teeth for a limited number of secondary outcome measures.One prospective cohort study, reporting data from a subgroup of 416 healthy male participants, aged 24 to 84 years, compared the effect of the absence (previous removal or agenesis) against the presence of asymptomatic disease-free impacted wisdom teeth on periodontitis and caries associated with the distal of the adjacent second molar during a follow-up period of three to over 25 years. Very low quality evidence suggests that the presence of asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting the adjacent second molar in the long term. In the same study, which is at serious risk of bias, there is insufficient evidence to demonstrate a difference in caries risk associated with the presence or absence of impacted wisdom teeth.One RCT with 164 randomised and 77 analysed adolescent participants compared the effect of extraction with retention of asymptomatic disease-free impacted wisdom teeth on dimensional changes in the dental arch after five years. Participants (55% female) had previously undergone orthodontic treatment and had 'crowded' wisdom teeth. No evidence from this study, which was at high risk of bias, was found to suggest that removal of asymptomatic disease-free impacted wisdom teeth has a clinically significant effect on dimensional changes in the dental arch.The included studies did not measure our other secondary outcomes: costs, other adverse events associated with retention of asymptomatic disease-free impacted wisdom teeth (pericoronitis, root resorption, cyst formation, tumour formation, inflammation/infection) and adverse effects associated with their removal (alveolar osteitis/postoperative infection, nerve injury, damage to adjacent teeth during surgery, bleeding, osteonecrosis related to medication/radiotherapy, inflammation/infection). AUTHORS' CONCLUSIONS: Insufficient evidence is available to determine whether or not asymptomatic disease-free impacted wisdom teeth should be removed. Although asymptomatic disease-free impacted wisdom teeth may be associated with increased risk of periodontitis affecting adjacent second molars in the long term, the evidence is of very low quality. Well-designed RCTs investigating long-term and rare effects of retention and removal of asymptomatic disease-free impacted wisdom teeth, in a representative group of individuals, are unlikely to be feasible. In their continuing absence, high quality, long-term prospective cohort studies may provide valuable evidence in the future. Given the lack of available evidence, patient values should be considered and clinical expertise used to guide shared decision making with patients who have asymptomatic disease-free impacted wisdom teeth. If the decision is made to retain asymptomatic disease-free impacted wisdom teeth, clinical assessment at regular intervals to prevent undesirable outcomes is advisable.

Accuracy of assessing the mandibular canal on cone-beam computed tomography: a validation study.

PURPOSE: To establish the accuracy of cone-beam computed tomographic (CBCT) views in determining the position and diameter of the mandibular canal. MATERIALS AND METHODS: Two freshly frozen cadaver heads, 1 dentate and 1 edentate, were used to acquire CBCT scans. Measurements on cross-sectional CBCT images were compared with measurements on digitized histologic sections of the same regions in the mandibles. The Student t test was used for statistical analysis. RESULTS: Comparing CBCT with histologic measurements showed that the position of the mandibular canal differed up to 0.47 mm (standard deviation, 0.29 mm). Mandibular canal diameters were up to 22.8% smaller in the CBCT planes. For the dentate jaw, these differences were statistically significant. CONCLUSION: To be safe, when assessing the mandibular canal position on CBCT views, a 0.76-mm deviation should be taken into account. Because the diameter of the mandibular canal is displayed smaller, an enlargement by 0.74 mm is recommended.

Coronectomy may be a way of managing impacted third molars.

DATA SOURCES: TPubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL) and the grey literature database SIGLE. STUDY SELECTION: Randomised controlled trials (RCTs) and non-randomised controlled trials (CCTs) that compared coronectomy with total removal for third molar extractions with high risk of nerve injury were included. DATA EXTRACTION AND SYNTHESIS: Data were extracted independently and in duplicate by two reviewers. Risk of bias was assessed according to the Cochrane Reviewers' Handbook. Meta-analysis and sensitivity analysis were performed. RESULTS: Four studies (two RCTs and two CCTs) involving 699 patients and 940 third molars were included. Pooled risk ratios for coronectomy compared with total removal are shown in table 1.Coronectomy was changed to total removal during surgery due to root loosening or mobilisation in 2.3% to 38.3% of cases. In 0% to 4.9% of cases reoperation was required in the coronectomy group due to persistent pain, root exposure or persistent apical infections. Root migration was only reported in three studies and ranged from 13.2% to 85.9%. CONCLUSIONS: We suggest that coronectomy can protect inferior alveolar nerves in the extraction of third molars with high risk of nerve injury as compared with total removal, and that the risk ratios of post-operative infections were similar between the two surgical modalities.

Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth.

BACKGROUND: The prophylactic removal of asymptomatic impacted wisdom teeth is defined as the (surgical) removal of wisdom teeth in the absence of local disease. Impacted wisdom teeth may be associated with pathological changes, such as inflammation of the gums around the tooth, root resorption, gum and alveolar bone disease, damage to the adjacent teeth and the development of cysts and tumours. Other reasons to justify prophylactic removal have been to prevent late incisor crowding. When surgical removal is carried out in older patients, following the development of symptoms, the risk of postoperative complications, pain and discomfort increases. Nevertheless, in most developed countries prophylactic removal of trouble-free wisdom teeth, either impacted or fully erupted, has long been considered as 'appropriate care' and is a very common procedure. There is a need to determine whether there is evidence to support this practice. OBJECTIVES: To evaluate the effects of prophylactic removal of asymptomatic impacted wisdom teeth in adolescents and adults compared with the retention (conservative management) of these wisdom teeth. SEARCH METHODS: The following electronic databases were searched: the Cochrane Oral Health Group's Trials Register (to 30 March 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE via OVID (1950 to 30 March 2012), and EMBASE via OVID (1980 to 30 March 2012). There were no restrictions on language or date of publication. SELECTION CRITERIA: All randomised controlled trials (RCTs) on adolescents and adults comparing the effect of prophylactic removal of asymptomatic impacted wisdom teeth with no-treatment (retention). DATA COLLECTION AND ANALYSIS: Six review authors screened the results of the search and assessed whether trials met the inclusion criteria for the review. Data extraction and risk of bias assessment were conducted in duplicate and independently by six review authors. Where information was unclear, authors of studies were contacted for additional information. MAIN RESULTS: No RCTs were identified that compared the removal of asymptomatic wisdom teeth with retention and reported quality of life. One RCT on adolescents was identified that compared the removal of impacted mandibular wisdom teeth with retention and only examined the effect on late lower incisor crowding. This study at high risk of bias provided no evidence that extraction of wisdom teeth had an effect on lower incisor crowding over 5 years. AUTHORS' CONCLUSIONS: Insufficient evidence was found to support or refute routine prophylactic removal of asymptomatic impacted wisdom teeth in adults. A single trial comparing removal versus retention found no evidence of a difference on late lower incisor crowding at 5 years, however no other relevant outcomes were measured.Watchful monitoring of asymptomatic third molar teeth may be a more prudent strategy.