The accidental displacement of tooth roots into the mandibular canal is a serious complication during tooth extractions in oral and maxillofacial surgery, often resulting in direct damage to the structural and functional integrity of the inferior alveolar neurovascular bundle (IANB). This article reviews the anatomical features of the mandibular canal, the IANB, and adjacent tooth roots; identifies high-risk factors and anatomically vulnerable sites for root displacement; and outlines the clinical manifestations and radiographic characteristics of intraoperative root intrusion into the mandibular canal. Furthermore, management principles, surgical approaches and techniques, inferior alveolar nerve injury treatment, and prognostic considerations are discussed. The aim of this review is to provide a comprehensive clinical reference for improving surgical outcomes, and reducing postoperative complications.
Humans ; Tooth Extraction/adverse effects* ; Mandible/surgery* ; Tooth Root ; Mandibular Nerve/anatomy & histology* ; Postoperative Complications/prevention & control* ; Intraoperative Complications ; Mandibular Nerve Injuries/etiology*

It has recently been reported that long-standing post-traumatic open bite can be successfully corrected with botulinum toxin type A (BTX-A) injection into the anterior belly of the digastric muscle (ABDM). The report documented an individual with bilaterally symmetrical and otherwise unremarkable anterior digastric musculature. However, the existence of variant anterior digastric musculature is common and may complicate the management of anterior open bite with BTX-A injection. Screening for variant ABDM can be accomplished via ultrasound, computed tomography, and magnetic resonance imaging. Screening for variant ABDM should be performed prior to BTX-A injection in order to account for musculature that may exert undesired forces, such as inferolateral deviation, on the anterior mandible in patients with anterior open bite.
Anatomy, Regional ; Botulinum Toxins, Type A* ; Humans ; Magnetic Resonance Imaging ; Malocclusion ; Mandible ; Mandibular Injuries ; Mass Screening* ; Nerve Block ; Open Bite* ; Orthognathic Surgery ; Ultrasonography

It is difficult to distinguish the inferior alveolar nerve (IAN) from other tissues inside the IAN canal due to their similar CT values in the X image which are smaller than that of the bones. The direct reconstruction, therefore, is difficult to achieve the effects. The traditional clinical treatments mainly rely on doctors' manually drawing the X images so that some subjective results could not be avoided. This paper proposes the partition reconstruction of IAN canal based on shape features. According to the anatomical features of the IAN canal, we divided the image into three parts and treated the three parts differently. For the first, the directly part of the mandibular, we used Shape-driven Level-set Algorithm Restrained by Local Information (BSLARLI) segment IAN canal. For the second part, the mandibular body, we used Space B-spline curve fitting IAN canal's center, then along the center curve established the cross section. And for the third part, the mental foramen, we used an adaptive threshold Canny algorithm to extract IAN canal's edge to find center curve, and then along it established the cross section similarly. Finally we used the Visualization Toolkit (VTK) to reconstruct the CT data as mentioned above. The VTK reconstruction result by setting a different opacity and color values of tissues CT data can perspectively display the INA canal clearly. The reconstruction result by using this method is smoother than that using the segmentation results and the anatomical structure of mental foramen position is similar to the real tissues, so it provides an effective method for locating the spatial position of the IAN canal for implant surgeries.
Algorithms ; Humans ; Image Processing, Computer-Assisted ; Mandible ; innervation ; Mandibular Nerve ; anatomy & histology

INTRODUCTIONThe lingual, inferior alveolar and auriculotemporal nerves, being branches of the posterior division of the mandibular nerve, mainly innervate the mandibular teeth and all the major salivary glands. Anomalous communications among these branches are widely reported due to their significance to various treatment procedures undertaken in the region. This study was performed as detailed exploration of the functional perspectives of such communicating branches would further enhance the scope of these procedures.

METHODSA total of 36 specimens were dissected to examine the infratemporal region. The branches from the posterior division of the mandibular nerve--namely the lingual, inferior alveolar and auriculotemporal nerves--were carefully dissected, and their branches were studied and analysed for abnormal course.

RESULTSCommunication between branches of the posterior division of the mandibular nerve was observed in four specimens. In two of the four specimens, communication between the mylohyoid and lingual nerves was observed. A rare and seldom reported type of communication between the auriculotemporal and inferior alveolar nerves is described in this study. This communicating nerve split into two to form a buttonhole for the passage of the mylohyoid nerve.

CONCLUSIONSuch communicating branches between nerves found in this study are developmental in origin and thought to maintain functional integrity through an alternative route.

Cadaver ; Female ; Humans ; Lingual Nerve ; anatomy & histology ; Male ; Mandibular Nerve ; anatomy & histology ; Neck Muscles ; innervation ; Tongue

INTRODUCTION: To correct the facial asymmetry by mandibular jaw surgery, it is important to know the anatomy of the mandible including the mandibular canal positioning of patients with facial asymmetry. This study was performed to evaluate the differences in the cross-sectional surface in the body of the mandible between the deviated side and opposite side in patients with facial asymmetry. MATERIALS AND METHODS: The study was conducted on 37 adult patients composed of 2 groups, the asymmetry group (n=20) and non-asymmetry group (n=17). Using the cross-sectional computed tomography (CT) images, the distance from the buccal aspect of the mandibular canal to the outer aspect of the buccal cortex, distance from the buccal aspect of the mandibular canal to the inner aspect of the buccal cortex, distance from the inferior aspect of the mandibular canal to the inferior border of the mandible, thickness of the mandible, and cross-sectional surface area of the mandible were measured in each side of the mandible. RESULTS: The cross-sectional area of the mandible including the mandibular canal positioning in the deviated side was not statistically different from the opposite side in the asymmetry group. Only the distance from the inferior aspect of the mandibular canal to the inferior border of the mandible in the ramus area of the deviated side was significantly longer than opposite side. On the other hand, the bucco-lingual width of the asymmetry group was thinner than the non-asymmetry group. CONCLUSION: The cross-sectional area including the mandibular canal of the mandible did not appear to be modified by the facial asymmetry.
Adult ; Anatomy, Cross-Sectional ; Facial Asymmetry ; Hand ; Humans ; Mandible ; Mandibular Nerve ; Orthognathic Surgery

OBJECTIVEThe aim of this study was to rebuild the anatomic structures of the mandibular bone and the canal, and to testify the reliability of the rebuilt model.

METHODS15 mandibular bones with teeth are chosen, and a three-dimensional model was built with the method of CT. The slices vertical to the compensating curve were made in every dental position. Then the authors collected the data of alveoli and mandibular canal in every slice. The same work was done to the bone specimen, and then comparative analysis was done.

RESULTSThe wideness of the alveoli and 10 mm bellow increased from mesial to distal position. It was the same of the alveoli from the top to the bottom. The mandibular canal lied in the inner and inferior side of the mandibular body. There was no significant difference in data collected with these two methods.

CONCLUSIONDifferent types of dental implants should be chosen according to the anatomic characteristic of the mandibular bone in every dental position before the operation to avoid complications. And a reliable, accurate and direct method of planning an implant operation is to rebuild a three-dimensional model.

Adult ; Computer Graphics ; Humans ; Mandible ; anatomy & histology ; diagnostic imaging ; innervation ; Mandibular Nerve ; anatomy & histology ; Models, Anatomic ; Tomography, Spiral Computed ; methods