Sonography in the diagnosis of peri-implant bone defects: An in vitro study on native human mandibles.

AIM: The aim of this study on native human cadavers was to compare clinical, sonographic, and radiological measurements of fenestrations, dehiscences, and 3-wall bone defects on implants. MATERIALS AND METHODS: The examination was carried out on five human mandibles. After the insertion of 27 implants, dehiscences (n = 14), fenestrations (n = 7) and 3-wall bone defects (n = 6) were prepared in a standardized manner. The direct measurement of the bone defects was carried out with a periodontal probe and the radiological examination was carried out using digital volume tomography (DVT). The ultrasound examination (US) was performed using a clinical 24-MHz US imaging probe. Means and standard deviations of the direct, US, and DVT measurements were calculated. Measurements were statistically compared using the Pearson correlation coefficient and Bland-Altman analysis. RESULTS: Bone defects were on average 3.22 ± 1.58 mm per direct measurement, 2.90 ± 1.47 mm using US, and 2.99 ± 1.52 mm per DVT assessment. Pairwise correlations of these measurements were R = .94 (p < .0001) between direct and US, R = .95 (p < .0001) between DVT and US, and R = .96 (p < .0001) between direct and DVT. The mean differences of the measurements (and 95% CI) between direct and US was 0.41 (-0.47 to 1.29), US and DVT 0.33 (-0.30 to 0.97), and direct and DVT 0.28 (-0.50 to 1.07). CONCLUSION: All peri-implant bone defects could be identified and sonographically measured. US measurements showed a strong correlation with direct and DVT measurements. The sonographic measurement accuracy was highest for dehiscences, followed by fenestrations and 3-wall bone defects.

Surgical Feasibility Study on Cadaver for Vascularized Wrist Joint Transplantation.

PURPOSE: Despite modern advancements in the treatment of late stages of wrist joint degeneration, few reliable options exist for patients requiring motion-preserving reconstruction of their radiocarpal and midcarpal joints. Vascularized composite allotransplantation (VCA) could be considered an option for wrist reconstruction in the future. The goal of this study was to describe the relevant anatomy and design a potential surgical technique for wrist VCA. METHODS: Anatomic studies were performed on 17 human upper extremities. The arterial system of each cadaver was injected with latex dye or radiographic contrast. After injecting a contrast medium visible on a computerized tomography (CT) scan, the initial three specimens were examined using microCT. This confirmed joint vascular patency and allowed for the dissection of the other specimens that were injected with latex for the study of joint vascularization and the design of the wrist VCA. We then outlined a donor and recipient surgical technique for transplant based on recipient CT scans. Customized cutting guides were designed for the transplant procedure. After the procedure, we performed angiography of the VCA to determine the vascularity of the transplant. RESULTS: Using a combined volar and dorsal approach, we were able to perform a complete wrist VCA procedure. After the completed transplant procedure, angiographic imaging of the specimens demonstrated that the flap dissection and transplantation preserved the nutrient endosteal supply to the distal end of the radius and ulna, as well as to the carpal bones and the metacarpal bases. CONCLUSIONS: The dissection of the donor, recipient, and the entire vascularized joint transplant procedure served to illustrate the anatomical feasibility of the cadaveric surgical technique. This establishes an anatomic basis for the possibility of future human clinical applications. CLINICAL RELEVANCE: This study helps investigate the anatomical feasibility of a wrist VCA.

Ultrasonographic assessment of the lateral pterygoid muscle for BoNT-A injection.

The upper head of the lateral pterygoid muscle (LPM) is known to insert into the capsule of the temporomandibular joint and articular disc, and therefore its relationship with temporomandibular disorders (TMD) has been consistently suggested. The aim of the study was to determine the anatomical features of the LPM using ultrasonographic (US) imaging. Around 120 hemifaces from 60 healthy Korean volunteers were included in this study. US images were taken with the subject's mouth 2 cm open. The transducer was placed at a position where the infratemporal fossa could be observed through the mandibular notch, and its position was recorded. The locations of the coronoid process (CorP), lateral margin of the condylar process (ConP), and midpoint of CorP and ConP (MP) were measured with reference to the ala-tragus line. The thicknesses of the skin and subcutaneous tissue, the masseter muscle, the temporalis muscle, and the depth of the LPM were measured at the MP. The masseter muscle, temporalis muscle, and LPM were observed in all cases and located in order from superficial to deep. The MP was located 39.6 ± 3.3 mm anterior and 7.8 ± 1.6 mm inferior to the tragus. The thicknesses of the skin and subcutaneous tissue, the masseter muscle, the temporalis muscle, and the depth of the LPM at the MP were 9.7 ± 1.0, 10.3 ± 1.3, 10.9 ± 1.6, and 30.9 ± 1.9 mm, respectively. The information reported in this study may be useful for determining the location of the LPM and adjacent anatomical structures in TMD patients and provide accurate and safe injection guidelines.

A rare case of the auriculotemporal and inferior alveolar nerves communication.

This case study describes anatomical variations in the branching pattern of the posterior division of the trigeminal nerve and its clinical implications for dental and craniofacial surgery. The study presents two uncommon variations observed in an elderly male cadaver. A communicating branch connecting one of three roots of the auriculotemporal nerve and inferior alveolar nerve just before entering the mandibular foramen on the right side, and three communicating branches between the IAN and lingual nerve on the left side. The presence of such variations may complicate anesthesia associated with oral surgery procedures.

Does the fixture thread depth affect the accuracy of implant placement during fully guided immediate implant placement?: A human cadaver study.

BACKGROUND: The fixture thread depth reportedly influences the primary stability of dental implant, but its effect on the positional accuracy in immediate implant placement has not been reported previously. MATERIALS AND METHODS: Fifty-six single-rooted, anterior and premolar teeth were extracted from six human cadavers, followed by installing either regular-threaded implants (RT group, N = 30) or deep-threaded implants (DT group, N = 26) completely relying on the surgical guide. Optical impressions taken after osteotomy and fixture installation were superimposed with the preoperative virtual planning data to measure the vertical, angular, platform and apex deviations that occurred during osteotomy and installation. RESULTS: While the osteotomy deviations were similar between the two groups, the angular and apex deviation of the DT group (2.67 ± 2.56°; 1.04 ± 0.49 mm, respectively) were significantly larger than those of the RT group (1.61 ± 1.04°; 0.67 ± 0.41 mm, respectively) during installation (p < .05). When the installation deviations were analysed in the anterior and premolar areas separately, the angular, platform and apex deviations of the DT group (3.05 ± 3.26°; 0.75 ± 0.32 mm; 1.08 ± 0.56 mm, respectively) were significantly larger than those of the RT group (1.56 ± 0.73°, 0.59 ± 0.28 mm; 0.62 ± 0.38 mm, respectively) in the anterior site (p < .05), whereas there was no significant intergroup difference in the premolar site. CONCLUSION: In immediate-implant surgery, using an implant with a deeper thread might increase the deviations during installation, especially in the anterior area.

What is a superior labial frenulum? An anatomical and histological study.

Anatomy of the superior labial frenulum (SLF), at first glance, seems to be well established. However, existing studies on the SLF lack description of the incisivus labii superioris (ILS), which cannot be ignored when discussing the SLF. We believe that thorough understanding of the SLF necessitates the anatomical knowledge of the ILS. This study aimed to elucidate the anatomical relationship between the orbicularis oris (OO), ILS, and SLF. A total of 20 formalin fixed human cadaveric specimens were used for gross anatomical and/or histological observation. For histological observation, all specimens were stained with Masson-trichrome. The SLF was a mucosal fold between the gingival mucosa and alveolar mucosa with connective tissue deep to it. The connective tissue attached to the alveolar bone in the junction between the right and left ILS. Skeletal muscle fibers other than orbicularis oris was found in one specimen, which were considered the ILS. During a frenulectomy, removal of the connective tissue bundle is required to prevent recurrence of the high SLF insertion.

Who really needs a Metaverse in anatomy education? A review with preliminary survey results.

The term Metaverse ("meta" defined as beyond, transcendence or virtuality, and "verse" meaning universe or world) denotes a "virtual reality space" for anatomy teaching. To ascertain how many anatomists are familiar or are using this adjunct in teaching, we conducted a short survey at the 2022 annual meeting of the American Association of Clinical Anatomists (AACA). Interestingly, only six respondents (9.4%) had used a Metaverse for teaching anatomy. Moreover, the vast majority of attendees were anatomy educators or basic science faculty, but not practicing physicians/surgeons or other actively practicing health care professionals; a group where this technology has been used much more commonly. The present manuscript was authored by anatomy educators, practicing physicians and other actively practicing health care professionals with backgrounds in diverse medical fields, that is, anatomists, medical doctors, physician assistants, dentists, occupational therapists, physical therapists, chiropractors, veterinarians, and medical students. Many of these authors have used or have been exposed to a Metaverse in the clinical realm. Therefore, the aim of the paper is to better understand those who are knowledgeable of a Metaverse and its use in anatomy education, and to provide ways forward for using such technology in this discipline.

The sublingual branch of the lingual nerve: Anatomical study and suggestion for a new terminology.

The lingual nerve carries somatosensory fibers from the anterior two-thirds of tongue. The parasympathetic preganglionic fibers arising from the chorda tympani also travel with the lingual nerve in the infratemporal fossa to synapse in the submandibular ganglion to innervate the sublingual gland. However, only a few studies have investigated the specific nerve that innervates the sublingual gland and surrounding tissue i.e., the so-called sublingual nerve. Therefore, this study aimed to clarify the anatomy and definition of the sublingual nerves. Thirty sides from formalin fixed cadaveric hemiheads underwent microsurgical dissection of the sublingual nerves. The sublingual nerves were found on all sides and categorized into three branches, i.e., branches to the sublingual gland, branches to the mucosa of the floor of the mouth, and gingival branches. Additionally, branches to the sublingual gland were subcategorized into types I and II based on the origin of the sublingual nerve. We suggest that the lingual nerve branches should be categorized into five branches, i.e., branches to the isthmus of the fauces, sublingual nerves, lingual branches, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion.

Combined cone-beam CT imaging and microsurgical dissection of cadaver specimens to study cerebral venous anatomy: a technical note.

PURPOSE: Cadaver dissections and X-ray based 3D angiography are considered gold standards for studying neurovascular anatomy. We sought to develop a model that utilize the combination of both these techniques to improve current tools for anatomical research, teaching and preoperative surgical planning, particularly addressing the venous system of the brain. MATERIALS AND METHODS: Seven ethanol-fixed human cadaveric heads and one arm were injected with a latex-barium mixture into the internal jugular veins and the brachial artery. After the ethanol-based fixation, specimens were scanned by high-resolution cone-beam CT and images were post-processed on a 3D-workstation. Subsequent, microsurgical dissections were performed by an experienced neurosurgeon and venous anatomy was compared with relevant 3D venograms. RESULTS: Latex-barium mixtures resulted in a homogenous cast with filling of the cerebral venous structures down to 150 µm in diameter. The ethanol-based preparation of the cadaveric brains allowed for near-realistic microsurgical maneuverability during dissection. The model improves assessment of the venous system for anatomical education and hands-on surgical training. CONCLUSION: To our knowledge we describe the first preparation method which combines near-realistic microsurgical dissection of human heads with high-resolution 3D imaging of the cerebral venous system in the same specimens.

Impact of modified teaching strategies used in a gross anatomy course on the academic performance of dental students during the COVID-19 pandemic.

INTRODUCTION: Modified teaching strategies (MTS), asynchronous online teaching and smaller dissection groups, were applied to a gross anatomy course for dental students in the National Taiwan University in April 2020 in response to the COVID-19 pandemic. This study aimed to investigate the effects and perceptions of MTS on dental students. MATERIALS AND METHODS: Scores for anatomy examinations for 2018-2019 (without MTS) and 2019-2020 (with MTS) cohorts were compared to explore the effect on academic performance. Moreover, questionnaire from the 2019-2020 cohort was analysed to determine dental students' perceptions about MTS. RESULTS: The lecture performance in the final examination of the second semester for the 2019-2020 cohort was significantly higher than that of the first semester (pre-COVID-19) and that for the 2018-2019 cohort. However, the laboratory performance in the midterm examination of the second semester for the 2019-2020 cohort was significantly lower than that for the 2018-2019 cohort and showed no difference in the final examination of the first semester. The questionnaires revealed that the majority of students displayed positive attitudes towards MTS and agreed with the importance of peer discussion during laboratory dissection. CONCLUSIONS: Asynchronous online learning for anatomy lecture may be beneficial for dental students; however, a smaller dissection group accompanied by reduced peer discussion may temporarily exert negative effects on their laboratory performance at the beginning of the application. Furthermore, more dental students exhibited positive perceptions towards smaller dissection groups. These findings could illuminate the learning condition of dental students in anatomy education.

The transversoclasiotome: a novel instrument for examining the vertebral artery.

Opening the foramen transversarium of the cervical vertebrae is necessary for accessing the vertebral vessels. There are no specialist tools for cutting the anterior lamina of the transverse processes, and alternatives lead to questionable results. A novel tool, the transversoclasiotome, is described and tested. The literature and patent databases were systematically reviewed. A blueprint of the transversoclasiotome was created, and the prototype was tested through autopsy on ten fresh-frozen cadavers within our Body Donation Program. The transversoclasiotome consists of two delicate branches mounted as a scissor, one a cutting jaw and the other a knocker with a rounded tip, both angled 30° to the principal axis. The jaws shut, facing each other in parallel. The cutting jaw corresponds to a slit on the knocker profile without protruding beyond it even when entirely closed. It acts by cutting and wedging. The testing autopsies demonstrated its suitability for its purpose, with an adequate response to the pressure exerted on the bone lamina. The section cut cleanly, without sliding off while closing on the bone. The vertebral vessels were not injured either during instrument insertion or cutting. Their morphological features are described. The transversoclasiotome has been proven appropriate for sectioning the anterior lamina of transverse processes of the cervical vertebrae. It meets the needs of clinical anatomy in teaching and training clinicians or surgeons, forensic clinical anatomy during medico-legal investigation, and research.

A disaster victim identification workshop focused on forensic odontology using embalmed human remains.

A high number of victims of mass casualty incidences are identified through their teeth. While forensic odontologists need to have a complex skillset during a disaster victim identification (DVI) response, hands-on training opportunities are rare. In countries with very limited forensic casework, such as New Zealand, many forensic odontologists find it difficult to achieve the number of annual forensic dental identifications required to maintain their credentialling. This report details the development of a hands-on forensic odontology-focused DVI workshop using human Crosado-embalmed remains. Anonymous participant evaluations, including five-point Likert and open-ended items, were performed in both years the workshop was held. A total of 10 and 17 participants, predominantly dentists, attended the workshop in 2020 and 2021, respectively. Participant feedback was extremely positive. Likert items were statistically similar between participants in both years. Open-ended items revealed positive feedback regarding the use of cadaveric remains, the gained hands-on experience, or the teamwork aspect. Participants who attended the workshop in both years commented on the positive aspect of repetition to cement their skills. As areas of improvement, participants named (for example) time management and the number of portable X-ray devices, leading to changes that were implemented in 2021. Moreover, the participants expressed interest to further their skills on decomposed, burnt, and fragmented human remains, which for ethical reasons has yet to be implemented. The DVI workshop described here, using embalmed human remains, provides an opportunity to add dental identifications toward annual credentialling requirements for forensic odontologists. Participants rated the course to be excellent overall and highly relevant for their role. For future workshops, there is an interest to include further aspects of the DVI response such as fingerprinting or police work as well as remains, which are altered due to natural or physical reasons.

A critical analysis of research methods and experimental models to study dentinal microcracks.

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

Guidelines for cadaver dissection in education and research of clinical medicine (The Japan Surgical Society and The Japanese Association of Anatomists).

This article translates the guidelines for cadaver surgical training (CST) published in 2012 by Japan Surgical Society (JSS) and Japanese Association of Anatomists from Japanese to English. These guidelines are based on Japanese laws and enable the usage of donated cadavers for CST and clinical research. The following are the conditions to implement the activities outlined in the guidelines. The aim is to improve medicine and to contribute to social welfare. Activities should only be carried out at medical or dental universities under the centralized control by the department of anatomy under the regulation of Japanese law. Upon the usage of cadavers, registered donors must provide a written informed-consent for their body to be used for CST and other activities of clinical medicine. Commercial use of cadavers and profit-based CST is strongly prohibited. Moreover, all the cadaver-related activities except for the commercial-based ones require the approval of the University's Institutional Review Board (IRB) before implementation. The expert committee organized at each university for the implementation of CST should summarize the implementation of the program and report the details of the training program, operating costs, and conflicts of interest to the CST Promotion Committee of JSS.

Variations in the venous supply of the floor of the oral cavity: Assessment of relative hemorrhage risk during surgery.

There is little anatomical evidence about the venous plexus in the floor of the oral cavity, although venous injury can elicit late postoperative bleeding after oral surgery and it is difficult to identify the exact location of such an injury. The aim of this study was to assess the relative risk for venous injury during surgery. We investigated the course patterns of the venous plexus in the floor of the oral cavity and analyzed their relationships to those of the arteries using 23 human cadavers (41 halves) in the anatomy course at Niigata University during 2016-2018. The venous plexus in the floor of the oral cavity comprised the perforating submental vein, the vena comitans of the hypoglossal nerve, the vena comitans of the submandibular duct, the vena comitans of the lingual nerve, the sublingual vein, and the deep lingual vein. Individual variations of this plexus include duplications or absences of some veins. There is a high incidence of a submental branch running above the mylohyoid or perforating submental artery in the sublingual fossa among individuals with the perforating submental vein piercing the mylohyoid muscle, whereas the sublingual artery has a high incidence there when there is no perforating submental vein. The course patterns of arteries in the floor of the oral cavity can be predicted by estimating the course patterns of the submental veins. The course patterns of the submental veins or veins associated with the nerves and submandibular duct need to be carefully considered during surgery.

Microsurgical Anatomy of the Superior Wall of the Mandibular Canal and Surrounding Structures: Suggestion for New Classifications for Dental Implantology.

Our goal was to clarify the relationship between the superior wall of the mandibular canal and the presence of teeth. We also sought to study the structural changes of the mandibular canal after tooth loss. Twenty sides from 10 dry mandibles derived from six males and four females were used for this study. The age of the specimens at the time of death ranged from 57 to 91 years. The mandibles were cut in the midline resulting in 20 hemi-mandibles. The presence of teeth (from the second premolar to the third molar) was recorded for each hemi-mandible. The mandibular canal in the body of the mandible was divided into four areas, that is, Areas 1-4. The superior wall of the mandibular canal and a cancellous bone pattern above the mandibular canal were observed. Next, the mandibular canal was horizontally cut at its center and the superior wall of the mandibular canal observed inferiorly. A total of 75 areas (20 dentulous areas and 55 edentulous areas) were produced. The distal view was classified into three groups, Type I (trabecular pattern), Type II (osteoporotic pattern), and Type III (dense/irregular pattern). The Type I pattern was found in 60.0% (12/20) of the dentulous areas and 32.7% of the edentulous areas. While the Type II pattern was found in 15.0% (23/55) of the dentulous areas and 41.8% of the edentulous areas. The inferior view was classified into four groups depending on the surface of the superior wall of the mandibular canal, that is, Class I (trabecular pattern), Class II (osteoporotic pattern), Class III (dense/irregular pattern), and Class IV (smooth).The Class I pattern was seen most frequently (55.0%) in dentulous areas and the Class IV pattern (45.5%) most frequently in edentulous areas. Based on these results, we conclude that the superior wall of the mandibular canal could change following tooth loss. Clin. Anat. 33:223-231, 2020. © 2019 Wiley Periodicals, Inc.

Air dissection of the spaces of the head and neck: A new teaching and dissection method.

Our goal was to evaluate a new air dissection technique for the spaces of the head and neck using fresh-frozen cadavers. Eight sides from four fresh-frozen Caucasian cadavers were used in this study. Compressed air was initially placed into the pterygomandibular space while simultaneously observing the spaces of the head and neck. Subsequently, the pterygomandibular space on the contralateral side of the specimen was insufflated and observations made. For these methods, simultaneous observation of mediastina and lungs was made using intrathoracic endoscopy. On all sides, the buccal, submental, sublingual, parotid, parapharyngeal, and retropharyngeal spaces were insufflated on both ipsilateral and contralateral sides. Deviation of the larynx and trachea was observed externally and deviation of the mediastinum and lungs via intrathoracic endoscopy. We introduced air dissection into spaces of the head and neck. This new technique might help students, teachers, dentists, medical doctors, and other healthcare providers to better understand the three-dimensional anatomy of the spaces of the head and neck and their communicating pathways. Clin. Anat. 33:207-213, 2020. © 2019 Wiley Periodicals, Inc.

Three-Dimensional Reconstruction of the Genial Spinal Canal.

The aim of this anatomical study was to investigate the genial spinal canal histologically and to reconstruct it three-dimensionally to improve understanding of its anatomy and to reveal any differences between dentate and edentulous specimens. Two tissue blocks from the mandible between the left and right second incisors, one dentate and one edentulous, were fixed in 4.5% formaldehyde, decalcified and embedded in paraffin. Serial histological sections were prepared, stained with Azan and examined microscopically. Additionally, three-dimensional models of the blocks were reconstructed using microphotographs of the sections. The genial spinal canal in the dentate specimen contained a neurovascular bundle, which branched into a nerve innervating the incisor and a neurovascular bundle, whereas that in the edentulous specimen contained some nerves for vestibular gingival innervation and a vascular bundle. The results suggest differences in the genial spinal canal between dentate and edentulous mandibles. Further research is needed to confirm this finding. Clin. Anat., 33:1102-1108, 2020. © 2019 Wiley Periodicals, Inc.

Releasing incisions of the buccal periosteum adjacent to the lower molar teeth can injure the facial artery: an anatomical study.

PURPOSE: Periosteal releasing incision (PRI) techniques are often used with guided bone regeneration procedures. As complications such as intra- and postoperative bleeding have been noticed, we aimed to study and clarify these as related to the PRI, especially on the mandibular buccal periosteum. METHODS: Fourteen sides from seven fresh-frozen Caucasian cadaveric heads were used in this study. The seven cadavers were derived from two females and five males. The mean age at the time of death was 75.9 ± 10.8 years. The PRI was made using a no. 15c blade using a surgical microscope. Subsequently, the fat tissue lateral to the periosteum was slightly dissected. The diameter of the facial artery (or its branch) and closest relationship between the tooth and position of the artery was recorded. Finally, the artery was traced back proximally to clarify its origin. RESULTS: On all sides, the inferior labial artery (ILA) was identified in the fat tissue lateral to and close to the periosteum. The ILA was closest to the periosteum at the midpoint of the PRI (approximately between the first and second molar teeth area or 10 mm mesial to the apex of the retromolar pad). The mean diameter of the ILA was 2.72 ± 0.26 mm. CONCLUSION: This anatomical finding should encourage dentists to make the PRI incision without invading the tissue underneath the periosteum.

How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve.

PURPOSE: This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. METHODS: Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. RESULTS: On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. CONCLUSION: We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.