Artificial intelligence in positioning between mandibular third molar and inferior alveolar nerve on panoramic radiography.

Determining the exact positional relationship between mandibular third molar (M3) and inferior alveolar nerve (IAN) is important for surgical extractions. Panoramic radiography is the most common dental imaging test. The purposes of this study were to develop an artificial intelligence (AI) model to determine two positional relationships (true contact and bucco-lingual position) between M3 and IAN when they were overlapped in panoramic radiographs and compare its performance with that of oral and maxillofacial surgery (OMFS) specialists. A total of 571 panoramic images of M3 from 394 patients was used for this study. Among the images, 202 were classified as true contact, 246 as intimate, 61 as IAN buccal position, and 62 as IAN lingual position. A deep convolutional neural network model with ResNet-50 architecture was trained for each task. We randomly split the dataset into 75% for training and validation and 25% for testing. Model performance was superior in bucco-lingual position determination (accuracy 0.76, precision 0.83, recall 0.67, and F1 score 0.73) to true contact position determination (accuracy 0.63, precision 0.62, recall 0.63, and F1 score 0.61). AI exhibited much higher accuracy in both position determinations compared to OMFS specialists. In determining true contact position, OMFS specialists demonstrated an accuracy of 52.68% to 69.64%, while the AI showed an accuracy of 72.32%. In determining bucco-lingual position, OMFS specialists showed an accuracy of 32.26% to 48.39%, and the AI showed an accuracy of 80.65%. Moreover, Cohen's kappa exhibited a substantial level of agreement for the AI (0.61) and poor agreements for OMFS specialists in bucco-lingual position determination. Determining the position relationship between M3 and IAN is possible using AI, especially in bucco-lingual positioning. The model could be used to support clinicians in the decision-making process for M3 treatment.

Vestibular landmarks to minimize injury to the mental nerve during transoral endoscopic thyroidectomy-vestibular approach (TOETVA) procedure: an anatomical study / Puntos de referencia vestibulares para minimizar la lesión del nervio mentoniano durante el procemiento de abordaje vestibular de tiroidectomía endoscópica transoral (TOETVA): un estudio anatómico

SUMMARY: The aim of this study is to reveal the morphometry of the mental nerve to describe a safe zone for minimizing mental nerve damage during transoral endoscopic thyroidectomy-vestibular approach (TOETVA). This study was performed on 12 cadavers. Localization of mental foramen according to teeth, distances of buccogingival sulcus-lip (BG-L), mental foramen-midline (MF-Midline), mental foramen - buccogingival sulcus (MF - BG), commissure - branching point (Cm - Br), branching point - vertical projection of branching point on lower lip (Br - LVP), vertical projection of branching point on lower lip - commissure (LVP - Cm), commissure - midline (Cm - midline), angles of mental (AM), angular (AA) and labial branches (AL) and branching patterns were recorded. Type 1 was mostly found as branching pattern in this study (45.8 %). A new branching pattern (type 9) was found on one cadaver. Mental foramen was mostly located at level of second premolar teeth. According to morphometric results of this study; supero- lateral to course of angular branch and infero-medial to course of mental branch of mental nerve on lower lip after exiting the mental foramen were described as safe zones during surgery for preserving mental nerve and its branches.

RESUMEN: El objetivo de este estudio fue revelar la morfometría del nervio mental o mentoniano para describir una zona segura y de esta manera, minimizar el daño de este nervio durante la tiroidectomía endoscópica transoral-abordaje vestibular (TOETVA). Este estudio se realizó en 12 cadáveres. Se realizó la localización del foramen mentoniano según los dientes, distancias surco gingival-labio (BG-L), foramen mentoniano-línea mediana (MF-Midline), foramen mentoniano-surco gingival (MF-BG), comisura-punto de ramificación (Cm-Br), punto de bifurcación - pro- yección vertical del punto de bifurcación en el labio inferior (Br - LVP), proyección vertical del punto de bifurcación en el labio inferior - comisura (LVP - Cm), comisura - línea mediana (Cm - línea mediana), ángulos del mentón (AM). Se registraron ramos angulares (AA) y labiales (AL) y patrones de ramificación. El tipo 1 se encontró principalmente como patrón de ramificación en el 45,8 %. Se describe un nuevo patrón de ramificación (tipo 9) encontrado en un cadáver. El foramen mentoniano se localizaba mayoritariamente a nivel de los segundos premolares. Según los resultados morfométricos, supero-lateral al curso de la rama angular e infero-medial al curso de la rama mentoniana del nervio mentoniano en el labio inferior, después de salir del foramen mentoniano, se describieron las zonas seguras, para la cirugía y preservación del nervio mentoniano y de sus ramos.

Factors affecting root migration after coronectomy of the mandibular third molar.

ABSTRACT: Nerve injury especially inferior alveolar nerve (IAN) is the one of the complications that occur when the mandibular third molar (M3) is extracted and in case of high risk patients, coronectomy might be an alternative to tooth extraction. The purpose of this retrospective study was to analyze root migration and its influencing factors at 6 months after coronectomy in both 2- and 3-dimensions using periapical view and cone-beam computed tomography (CBCT). We analyzed 33 cases of root remnant after coronectomy and measured the amount of migration in CBCT. The following factors that could possibly affect root migration were also analyzed: age, gender, number of M3 roots, shape of M3s, Pell, and Gregory classification, mesiodistal (MD) angulation, buccolingual (BL) angulation, contact point with the second molar, root curvature, and complete removal of the coronal portion. Migration of greater than 2 mm was found in 64% of the roots in the 2-dimensional (2D) analysis, and the average root migration was 4.11 mm in the 3-dimensional (3D) analysis. The factors affecting migration were the root morphology, complete removal of the coronal portion, impaction depth, and MD angulation in the 2D analysis, and MD and BL angulation in the 3D analysis. Ensuring sufficient space for root migration especially considering angulation, depth and complete removal of the coronal portion might be important factors after coronectomy of the M3. Root remnant after coronectomy of M3 may migrate in young patients who has sufficient empty coronal space and this may reduce the nerve damage by the separation of IAN and M3.

Avoiding Inferior Alveolar Nerve Injury during Osseous Genioplasty: A Guide for the Safe Zone by Three-Dimensional Virtual Imaging.

BACKGROUND: No consensus exists about the safest position for performing the osseous genioplasty, with 5 to 6 mm below the mental foramen being the most frequently recommended position. This study intends to generate a safe distance guide to minimize the risk of inferior alveolar nerve injury during osteotomy. METHODS: Pretreatment cone-beam computed tomography-derived three-dimensional models from adult patients with skeletal class I to III patterns and cleft lip/palate deformity who underwent orthodontic-surgical interventions (n = 317) were analyzed. A three-dimensional vertical distance between the inferior margin of the mental foramen and the lowest point of the inferior alveolar nerve canal was measured in each three-dimensional hemimandible (n = 634). Statistical analysis was performed to generate the safe distance guide in a stepwise fashion at 95, 99, and 99.99 percent confidence levels. RESULTS: Class III (4.35 ± 1.42 mm) and cleft lip/palate (4.42 ± 1.53 mm) groups presented significantly (p < 0.001) larger three-dimensional distances than class I (3.44 ± 1.54 mm) and class II (3.66 ± 1.51 mm) groups. By considering the 5- to 6-mm safe distance parameter, 6.4, 5.0, 10.6, 16, and 9.9 percent of hemimandibles were at risk of osteotomy-induced nerve injury in the class I, class II, class III, cleft lip/palate, and overall cohorts, respectively. Overall, the safe distance zone to perform the osteotomy was set at 7.06, 8.01, and 9.12 mm below the mental foramen, with risk probabilities of 2.5, 0.5, and 0.0005 percent, respectively. CONCLUSION: This study contributes to patient safety and surgeon practice by proving a safe distance guide for genioplasty.

Anatomic Variations From 120 Mental Nerve Dissections: Lessons for Transoral Thyroidectomy.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach (TOETVA) is a promising technique for eliminating a neck incision. A new risk of TOETVA is the potential for injury to the mental nerves during placement of three oral endoscopic ports. A better understanding of the variations in mental nerve anatomy is needed to inform safer TOETVA technique. MATERIALS AND METHODS: We performed 120 dissections of mental nerve branches exiting the mental foramen in 60 human cadavers. Anatomic distances and relationships of the foramen to the midline were evaluated. Mental nerve branching patterns were studied and compared with previously reported classification systems to determine surgical safe zones free of nerve branches. RESULTS: The mean midline-to-mental foramen distance was 29.2 ± 3.3 mm, with high variability across individuals (18.8-36.8 mm). There were differences in this distance between the left and right foramina (29.8 ± 3.2 versus 28.8 ± 3.3 mm, P = 0.03). All mental nerve branches exiting the mental foramen distributed medially. The branching patterns were classified into eight distinct categories, three of which are previously undescribed. One of these novel patterns, occurring in 9.2% of cases, had a dense and wide clustering of branches traveling toward the midline. CONCLUSIONS: The location of the mental foramen and mental nerve branching patterns demonstrate high variability. To avoid mental nerve injury in TOETVA, we identify a safe zone for lateral port placement lateral to the plane of the mental foramen. Placement and extension of the middle port incision should proceed with caution, as clustering of mental nerve branches in this area can frequently be present.

CBCT does not reduce neurosensory disturbances after third molar removal compared to panoramic radiography: a systematic review and meta-analysis.

OBJECTIVES: The current dentistry scenario is showing an increase in the availability of cone-beam computed tomography (CBCT) in dental offices. Oral surgeons are using three-dimensional information as an additional tool to assess preoperative data for lower third molar (LTM) removal in moderate and high-risk cases of inferior alveolar nerve (IAN) injury diagnosed through the panoramic radiography (PR). The aim of this study is to identify whether CBCT examination reduces neurosensoric disturbances (ND) following the removal of the LTM when compared to PR. MATERIALS AND METHODS: PubMed, Embase, Web of Science, Science Direct, and Scopus electronic databases were searched for studies published up to February 2019. The gray literature was also searched including papers that eventually met the eligibility criteria. Meta-analysis was performed using the comprehensive meta-analysis software, p < 0.05 considered significant. RESULTS: Among the search, 6 studies met all eligibility criteria. There was no statistically significant difference between the two groups (PR and CBCT) in all six studies regarding reducing ND (95%. Confidence interval, 0,788-1734; heterogeneity: Q = 10,361; I2 = 22.788%). CONCLUSIONS: CBCT was not superior to PR in avoiding ND. However, further studies are necessary with standardized parameters for a better comparability between variables in the studies. CLINICAL RELEVANCE: To better understand the CBCT clinical applicability in LTM removal to avoid unnecessary extra radiation when compared to PR to the patient and to improve patient's prognosis.

Printing a Three-Dimensional Patient-Specific Safety Device for Reducing the Potential Risk of Mental Nerve Injury During Transoral Thyroidectomy.

BACKGROUND: Thyroidectomy transoral endoscopic thyroidectomy vestibular approach (TOETVA) is a safe and cosmetically appealing alternative for well-selected patients undergoing thyroidectomy. However, during TOETVA, placement of the two lateral trocars and/or manipulation of the surgical instruments through the trocars may potentially injure and/or compress the mental nerve (MN) because the actual location of the nerve foramen may vary among individuals. The MN injury rate was reported to be as high as 75% in the initial period of robotic-assisted TOETVA. To reduce the potential risk of MN injury, we implemented a three-dimensional printing technology to develop a safety device for TOETVA. METHODS: The patient-specific safety device (PSSD) was a brace with an exact fit to the lower teeth and two safety markers on each side to indicate the location of the mental foramen. For patient in whom the brace would not be applicable, a 3D mandibular model was printed as a PSSD instead. We analyzed 66 patients undergoing TOETVA at our institution from March 2017 to March 2019. The preoperative details and complication profiles were also analyzed. RESULTS: With incorporation of the PSSD into our TOETVA procedure, there have been no cases of MN injury. CONCLUSIONS: Our own TOETVA series has demonstrated that the implementation of the PSSD has been successful in preoperatively identifying and preventing the potential risk of MN injury. Although the additional requirements of preoperative CT and time for fabricating the device impose limitations, the influence of the PSSD in TOETVA is positive.

Human cadaveric model for studying the preservation of mental nerve during transoral endoscopic thyroidectomy.

PURPOSE: Mental nerve (MN) injury can be caused by transoral endoscopic thyroidectomy vestibular approach (TOETVA). The purpose of this experimental study was to determine the location and distribution pattern of MN structures in relation to oral vestibular incisions. METHODS: Ten cadaver specimens were included, yielding a total of 20 MNs. The difference between standard 10-mm TOETVA median incision and modified incision (i.e. lower and perpendicular) was compared. RESULTS: All 20 MNs were successfully dissected and presented as bifid (100%), lateral toward medial direction. The branches of MNs were equally distributed into both right and left sides. Standard lateral 5-mm vestibular incisions did not determine any division of MN branches. Two left MNs (25%) and one right MN (12.5%) were injured by standard median vestibular incision. Using a more inferiorly positioned and a vertical median incision, the integrity of MN branches was preserved. CONCLUSIONS: Standard lateral 5-mm vestibular incisions are safe for determining MN integrity. The 10-mm median vestibular incision divided the medial ramifications of MN at a rate of 12-25%. These may result in MN ipsilateral or bilateral paralysis. Hence, it is recommended to locate the median incision more inferiorly or vertically.

The clinical application of mental nerve dissection in transoral endoscopic thyroidectomy via an oral vestibular approach.

BACKGROUND: Transoral endoscopic thyroidectomy vestibular approach is the natural orifice surgery to avoid surgical scars. However, mental nerve injury is a characteristic complication. Herein, we report the development of a novel method to dissect the mental nerve proactively during surgery to minimize the morbidity from mental nerve injury. METHODS: In this study, a total of 105 patients from June 2016 to February 2018 were categorized as the mental nerve dissection group (MND) or not mental nerve dissection group (NMND). We analyzed the demographics, operative data, hospital stay, pathologic results, and postoperative complications between the two groups. RESULTS: There were no significant differences with respect to age, gender, tumor size, extent of surgery, the amount of bleeding, or postoperative hospitalization between groups. The specimen removal time was shorter in the MND group. The average operation time in both groups was similar, but the operation time for a hemithyroidectomy with CND in the MND group was shorter than in the NMND group. The VAS pain scores and complication rates that included transient hypocalcemia, seroma, subcutaneous emphysema, transient, and permanent recurrent laryngeal nerve palsy did not differ significantly between groups. In terms of mental nerve injury, the morbidity rate in the MND group was lower than in the NMND group. CONCLUSIONS: The modified endoscopic thyroidectomy involving dissection of the mental nerve via the oral vestibular approach is safe and feasible. It is beneficial to protect the mental nerve and for specimen removal which is worth clinical promotion.

How to Avoid and Manage Mental Nerve Injury in Transoral Thyroidectomy.

Transoral endoscopic thyroidectomy by vestibular approach (TOETVA) represents an innovative and scarless technique for thyroid surgery. The procedure is conducted via a three-port technique at the oral vestibule using a 10mm port for the 30° endoscope and two additional 5mm ports for the dissecting and coagulating instruments. Patients meeting the following criteria can be considered as candidates for TOETVA: (a) an ultrasonographically (US) estimated thyroid diameter =10cm; (b) US-estimated gland volume =45mL; (c) nodule size =50mm; (d) presence of a benign tumor, such as a thyroid cyst or a single- or multinodular goiter; (e) Bethesda 3 and/or 4 categories, and (f) papillary microcar-cinoma without the evidence of metastasis. Beyond the classic complications of thyroid surgery, namely cervical hematoma, recurrent laryngeal nerve injury and hypoparathyroidism, novel consequences can occur as mental nerve (MN) injury. In this paper, leading experts in the field report on their current clinical experience with the TOETVA approach for thyroid gland surgery, with emphasis given to tips and tricks to avoid and manage MN injury.

CBCT study on the relationship between lingula and antilingula position in a Chinese Han population.

OBJECTIVE: The purpose of this article was to assess the anatomical relationship between the lingula and the antilingula by measuring the projection of lingula on the lateral side of the ramus on CBCT. METHODS: This study collected CBCT images of 204 mandibular halves in 102 Chinese patients without any damage. We projected the lingula to the lateral side of the mandibular ramus and examined the distance and position relationship between the projection point and the antilingula using three-dimensional computed tomography (3DCT) created by image software. RESULTS: In 204 sides the antilingula appeared in 92 cases, 52 on right and 40 on left. The antilingula was used as a fixed point, in four cases the lingula projection in the anterior superior part, 38 cases in the posterior superior part, 45 cases in the posterior inferior part and zero case in the anterior inferior part. Scatter plots diagrammatic representation in four quadrants centered on the antilingula showed that 79% cases (73/92) lied in a 90° fan shape ranged in 5-10 mm radius in the posterior superior and inferior quadrant. CONCLUSION: The lingula mainly located in the posterior superior and inferior part from the antilingula in a 90° fan shape ranged in 5-10 mm radius. The osteotomy incision should be avoided in this area.