Inferior Alveolar Canal Research Articles

Anatomical differences in lower third molars visualized by 2D and 3D X-ray imaging: clinical outcomes after extraction

The purpose of this study was to evaluate the relationship between third molars and the inferior alveolar canal using panoramic radiographs and cone beam computed tomography (CBCT) scans and to assess clinical outcomes after third molar removal retrospectively. The degree of superimposition, buccolingual position (buccal, central, and lingual) and physical relationship (separation, contact, and involved) were measured using CBCT scanning. Post-extraction complications were recorded. Based on radiographic evaluation, 45.9% of third molar roots were inside the inferior alveolar canal, 21.3% were in contact with the inferior alveolar canal, and 32.8% were separated from the canal. The frequency at which the mandibular canal was separated from the root apex was significantly higher when the canal was in the buccal position (80.0%) than in the central (20.0%) and lingual positions (0.0%). Although on panoramic radiographs all third molars were directly superimposed on the inferior alveolar canal, CBCT showed direct contact or canal involvement in 67.2% and separation of the canal from the root apex in 32.8%. Complications occurred in nine patients: eight had third molar root apices inside or in contact with the inferior alveolar canal. The prevalence of post-extraction complications correlated with the absence of cortication around the inferior alveolar canal.

Configuration of the inferior alveolar canal as detected by cone beam computed tomography

Aims:The aim of this study is to evaluate the course of the inferior alveolar canal (IAC) including its frequently seen variations in relation to root apices and the cortices of the mandible at fixed pre-determined anatomic reference points using cone beam volumetric computed tomography (CBVCT).Material and Methods:This retrospective study utilized CBVCT images from 44 patients to obtain quantifiable data to localize the IAC. Measurements to the IAC were made from the buccal and lingual cortical plates (BCP/LCP), inferior border of the mandible and the root apices of the mandibular posterior teeth and canine. Descriptive analysis was used to map out the course of the IAC.Results:IACs were noted to course superiorly toward the root apices from the second molar to the first premolar and closer to the buccal cortical plate anteriorly. The canal was closest to the LCP at the level of the second molar. In 32.95% of the cases, the canal was seen at the level of the canine.Conclusions:This study indicates that caution needs to be exercised during endodontic surgical procedures in the mandible even at the level of the canine. CBVCT seems to provide an optimal, low-dose, 3D imaging modality to help address the complexities in canal configuration.

Radiographic Study of Mental Foramen in a Selected Indian Population in Kheda District, Gujarat

Information on the knowledge of the mental foramen is important in clinical dentistry. The present study was undertaken to determine the most common position of mental foramen in randomly selected Indian population. Total 204 panoramic radiographs were evaluated, among them 184 were studied in terms of site, gender differences, symmetry of location, shape, distance from midline and continuity of the foramen with the canal and remaining 20 were considered as unidentified type. Total 368 mental foramen were evaluated, among them 242 (65.76%) were symmetrical in distribution and 126 (34.24%) were asymmetrical in distribution. The most common position for mental foramen (n = 242) relative to the teeth in the sample was between first and second premolar (n = 235, 63.86%). Same findings were observed in both sexes (male n = 130, 70.66% and female n = 105, 57.06%). The second most common position was in line with second premolar (n = 97, 26.36%). The most common shape of foramen is round (n = 178, 48.37%) followed by oval shape (n = 131, 35.60%). Most of the foramen were separated from the inferior alveolar canal (n = 197, 53.53%) and average distance from the midline is 28.44 mm in male and 26.89 mm in female.

Distribution of the lingual foramina in mandibular cortical bone in Koreans

ObjectivesThe interforminal region, between the mandibular foramen, is known as a relatively safe area that is free of anatomic structures, such as inferior alveolar nerve, submandibular fossa, and lingual side of the mandible is occasionally neglected for its low clinical importance. Even in the case of a severely constricted alveolus, perforation of the lingual cortical bone had been intended. However, anterior extension of the inferior alveolar canal, important anatomic structure, such as concavity of lingual bone, lingual foramina, and lingual canal, has recently been reported through various studies, and untypical bleeding by perforation of the lingual plate on implantation has also been reported. Therefore, in this study, we performed radiographic and statistical analysis on distribution and appearance frequencies of the lingual foramina that causes perforation of the mandibular lingual cortical bone to prevent complications, such as untypical bleeding, during surgical procedure.Materials and MethodsWe measured the horizontal length from a midline of the mandible to the lingual foramina, as well as the horizontal length from the alveolar crest to the lingual foramina and from the lingual foramina to the mandibular border by multi-detector computed tomography of 187 patients, who visited Dankook University Dental Hospital for various reasons from January 1, 2008 to August 31, 2012.ResultsFrom a total of 187 human mandibles, 110 (58.8%) mandibles had lingual foramina; 39 (20.9%) had bilateral lingual foramen; 34 (18.2%) had the only left lingual foramen; and 37 (19.8%) had the only right lingual foramen.ConclusionWhen there is consistent bleeding during a surgical procedure, clinicians must consider damages on the branches of the sublingual artery, which penetrate the lingual foramina. Also, when there is a lingual foramina larger than 1 mm in diameter on a pre-implantation computed tomography, clinicians must beware of vessel damage. In order to prevent these complications and progress with a safe surgical procedure, a thorough radiographic examination before the surgery is indispensable. Further, clinicians should retract lingual flap definitely to confirm the shape of the lingual bone and existence of the lingual foramina.

Correlation of mandibular impacted tooth and bone morphology determined by cone beam computed topography on a premise of third molar operation

To determine the width and morphology of the mandible in the impacted third molar region, and to identify the location of the mandibular canal prior to planning impacted third molar operations. Cone beam computed tomography (CBCT) data of 87 mandibular third molars from 62 Japanese patients were analyzed in this study. The width of the lingual cortical bone and apex-canal distance were measured from cross-sectional images in which the cortical bone was thinnest at the lingual side in the third molar region. Images were used for measuring the space (distance between the inner border of the lingual cortical bone and outer surface of the third molar root), apex-canal distance (distance from the root of the third molar tooth to the superior border of the inferior alveolar canal) and the cortical bone (width between the inner and outer borders of the lingual cortical bone). The means of the space, apex-canal distance and lingual cortical width were 0.31, 1.99, and 0.68mm, respectively. Impacted third molar teeth (types A-C) were observed at the following frequencies: type A (angular) 37%; type B (horizontal), 42%; type C (vertical), 21%. The morphology of the mandible at the third molar region (types D-F) was observed as: type D (round), 49%; type E (lingual extended), 18%; and type F (lingual concave), 32%. The width and morphology of the mandible with impacted teeth and the location of the mandibular canal at the third molar region could be clearly determined using cross-sectional CBCT images.

Unilocular radiolucency of the mandible

A 16-year-old girl presented with a 1-month history of a bony swelling in the body of the right mandible. The patient had undergone an endodontic procedure on the mandibular right first permanent molar (tooth #30) approximately 1 month previously for pain, swelling, and possible infection in the tooth. The swelling did not resolve after endodontic therapy, and she was referred to an oral surgeon for a biopsy. The patient’s medical history was noncontributory. Findings of the clinical examination revealed cortical expansion of the right mandibular body measuring approximately 2.0 cm in buccal/lingual dimension. The bone was covered by an intact mucosa without erythema or purulent drainage. Tooth #30 was clinically mobile, whereas the adjacent premolar and molar teeth were not mobile and tested vital. The patient denied experiencing paresthesia. A panoramic radiograph revealed a single, ovoid, unilocular radiolucency measuring 2.0 by 3.0 cm with distinct hyperostotic borders. The lesion surrounded the roots of tooth #30 and extended to the inferior border of the left mandibular body, involving the inferior alveolar nerve canal. The periodontal ligament space was symmetrically widened around the roots of tooth #30, with loss of the lamina dura and slight resorption of the mesial root apex. The interproximal crestal bone appeared intact both mesially and distally (Fig. 1).

Elimination of permanent injuries to the inferior alveolar nerve following surgical intervention of the “high risk” third molar

We aimed to find out whether improved preoperative assessment and surgical planning with cone beam computed tomography (CT) could reduce damage to the inferior alveolar nerve when high risk impacted mandibular third molars are extracted. We recorded the presence or absence of postoperative neuropathy after extraction of 200 lower third molars in 185 patients (where cone beam CT had shown contact between the nerve and root) after treatment in the oral surgery department of King's College Hospital. All patients had had cone beam CT of the teeth after panoramic radiography had indicated increased risk of injury to the nerve during extraction. Experienced oral surgeons did all the operations and postoperative reviews. Patients reported temporary alteration of sensation after operation in 12% of teeth but it resolved in all cases and no patient reported permanent loss of sensation. Permanent sensory disturbance in the distribution of the inferior alveolar nerve after third molars have been removed can be eliminated in high risk cases if operations are planned carefully (including cone beam CT), and the procedure is done by a skilled surgeon who has an appreciation of the anatomy of the nerve and roots, and an insight into the mechanical effect of their surgical manipulation. The incidence of permanent neurosensory dysfunction in this study was zero even though all teeth were intimately related to the inferior alveolar canal.

Proximity of Impacted Mandibular Third Molars to the Inferior Alveolar Canal and Its Radiographic Predictors: A Panoramic Radiographic Study

To assess the radiographic proximity of impacted mandibular third molars to the inferior alveolar canal on panoramic radiographs. The radiographic distance between the impacted mandibular third molars and inferior alveolar canal and the reliable radiographic risk predictor signs that indicate close proximity between these two structures were evaluated. The study comprised of 64 subjects with 68 symptomatic impacted mandibular third molars for whom panoramic radiographs were made. The radiographs were interpreted for type of impaction, radiographic distance between impacted mandibular third molars to inferior alveolar canal and presence of one or more of the seven radiographic risk predictor signs. Further, these teeth were surgically removed and the proximity was assessed based on the exposure of inferior alveolar canal/nerve which was considered as Gold standard. The overall mean distance from the impacted mandibular third molars to inferior alveolar canal was -0.50mm. Most of the samples (61.8%) extended beyond the superior border of the inferior alveolar canal with a mean distance of -1.40mm. Mesioangular impactions were found to be in the close proximity (-1.14mm) to inferior alveolar canal than any other type. Interruption of the white line was the only statistically significant radiographic risk predictor sign p = 0.006 (< 0.05) that indicated close proximity of impacted mandibular third molars to inferior alveolar canal. It can be concluded that panoramic radiographs are reliable in assessing the proximity of impacted mandibular third molars to inferior alveolar canal. Mesioangular impactions are more closely placed to inferior alveolar canal and interruption of the white line is the most reliable risk predictor sign on the panoramic radiographs.

The relative risk of neurosensory deficit following removal of mandibular third molar teeth: the influence of radiography and surgical technique

The aim of this study was to identify the relative risk of damage to the inferior dental (ID) and lingual nerves in patients undergoing lower third molar removal. A single surgeon reviewed 1,000 patients. Temporary ID neurosensory deficit was highest (11%) when root apices were intimate to the ID nerve and lowest (0.9%) when close or distant from the nerve. Permanent ID neurosensory deficit was 0.4% per tooth but only when intimate to the canal. Bone removal, tooth division, and lingual split technique increase the risk of excessive hemorrhage which appears to be linked to the highest risk of temporary ID neurosensory deficit (20%). Permanent lingual nerve injury was rare (0.06%) and not related to lingual retraction. Preoperative warning for lower third molar removal can be individually tailored depending on the intimacy of the ID canal to the root apices and the anticipated surgical technique.

Nanomedicine–Next Generation Technology Revolutionizing Medical Practice

Nanomedicine–Next Generation Technology Revolutionizing Medical Practice

Darkening of third molar roots on panoramic radiographs: is it really predominantly thinning of the lingual cortex?

This study investigated the exact intra-alveolar aetiology of a panoramic high-risk sign, darkening of the third molar roots. 83 mandibular third molar surgical removals demonstrating dark bands on the third molar roots in preoperative radiographs were included in this prospective study. Exposure of the inferior alveolar nerve (IAN), the root morphology of the third molar (e.g. groove or hook) and the integrity of the mandibular canal or lingual cortical wall were observed. Differences between single (increased radiolucency alone) and multiple darkening cases (increased radiolucency with accompanying ‘high risk’ signs) and between IAN exposure and groove formation were analysed. In 38 cases (45.8%), the IAN was visible during the operation. Groove was present in 37.4% of cases. 26.5% of the cases showed lingual cortical thinning, while specious root conformation explained the formation of darkening on the radiographic images of an additional 9.6% of the cases. IAN exposure (P<0.001) and groove formation (P<0.001) were significantly more frequent in multiple darkening cases than in single darkening cases. According to these findings, darkening of the third molar roots is more often the result of fenestration of the inferior alveolar canal wall or groove formation of the root than lingual cortical thinning.

Thickness of buccal bone in the mandible and its clinical significance in mono-cortical screws placement. A CBCT analysis

The aim of this study was to determine the safest length of monocortical screws that can be inserted for the treatment of mandibular fractures following Champy's technique. Fifty cone-beam computed tomography (CBCT) scans of hemi-mandibles were studied. Linear measurements were taken from the buccal cortical plate to the tooth apex, from the canine to the second premolar, and from the buccal cortical plate to the tooth apex and the inferior alveolar canal in the molar area. The minimum values of the horizontal distances both at the level of the apex and the inferior alveolar canal at the second molar were found to be 4mm, which is greater than those of the first molar. At the canine, first premolar and second premolars, the minimum values of the horizontal distances at the level of the apex was found to be 2mm, 2.33mm and 2mm, respectively. Stabilizing miniplates using 4mm screws both at the level of the apex and the inferior alveolar canal is safe in the second molar area, anterior to this, there is a risk of injury to tooth root and inferior alveolar nerve.

Residents' journal review

Residents' journal review

Altered sensation caused by peri-implantitis: a case report

Frequently reported is a case wherein a lesion caused by periodontitis or periapical lesion in a natural tooth enlarged, invaded the inferior alveolar nerve canal, and induced paresthesia. Cases wherein paresthesia occurred because of peri-implantitis have been rarely reported. The patient in this case report had experienced transient paresthesia after implant placement and recovered normal sensation 3 months later. Thirteen years later, this patient visited the authors' hospital with paresthesia in the same region because the peri-implantitis progressed to the apex of the implant. One week after removal of the implant, sense recovery and pain relief started, and 15 days after removal, the paresthesia and pain completely disappeared. For patients who experience transient paresthesia and recovery owing to nerve damage caused by the placement of an implant in the mandibular molar or premolar area, or in patients in whom the implant is close to the inferior alveolar nerve canal or the mental nerve, the spread of inflammation caused by peri-implantitis can induce paresthesia.

A retrospective comparison of the location and diameter of the inferior alveolar canal at the mental foramen and length of the anterior loop between American and Taiwanese cohorts using CBCT

The aim was to retrospectively compare the measurements of the location and size of the inferior alveolar canal at the mental foramen and the length of the anterior loop between two cohorts of Americans and Taiwanese using cone-beam computed tomography (CBCT). CBCT was performed with an I-CAT(®) Cone-Beam 3D Dental Imaging System and reconstructed into multiple-plane views to measure two populations. There was no statistically significant difference (P=0.2681) in the distance from the mental foramen to the inferior border of the mandible (mandibular border height) between Americans (9.84±2.01mm) and Taiwanese (10.13±1.66mm). No significant difference was found (p=0.1161) in the inferior alveolar canal diameter between these two cohorts (2.26±0.67 and 2.13±0.47mm, respectively). However, the anterior loop length of Taiwanese (7.61±1.81mm) was significantly longer than that of Americans (6.22±1.68mm) (P<0.0001). Our study indicated that (1) the location of mental foramen of Americans was closer to the inferior border of the mandible than Taiwanese; (2) the diameter of the inferior alveolar canal of Americans was larger than Taiwanese; (3) the anterior loop of Taiwanese was longer than Americans. These differences may be, at least partly, due to the racial influence and this information may possess potential valuable clinical relevance.

Summary of: Post-implant neuropathy of the trigeminal nerve. A case series.

Background The incidence of implant-related inferior alveolar nerve injuries (IANI) is steadily increasing within the UK population. Aims This study prospectively reviewed thirty cases (35% male; 65% female) of implant-related IANI seen in a specialist nerve injury clinic. Methods Neurosensory examinations were carried out to ascertain a quantifiable rating of the perception, pain profiling and functional difficulties. Data were analysed using SPSS software. Results Patients were aware of signing consent forms for the surgery in 11 cases and 8 of those felt they were not explicitly warned about nerve injury. Over 70% of patients were referred after six months post injury. Implant surgery planning involved intra-oral films only (30%), CBCT (10%), dental pantomograph (50%) and long cone peri-apical radiographs (48%). However, no radiographic evidence pre- or postoperatively was provided by the referring practitioner in 15% of cases. Intra-operative problems included bleeding and neurological symptoms. Proximity of the implant bed or implant to the inferior alveolar canal was evident radiographically. This showed contact with roof inferior alveolar nerve canal in 44% of cases, protrusion into the canal in 20% of cases, crossing of the canal in 20% cases and distance in one case, presumed to be due to local anaesthetic injury. All patients presented with a demonstrable neuropathy, which included neuropathic pain (50%) that interfered with speaking, kissing and socialising. Conclusions Consent, preoperative planning and appropriate referral were inadequate in provision of mandibular implants in this patient group. Recommendations have been proposed to improve practice and possible novel strategies are suggested for the prevention and improved management of these complications.

Post-implant neuropathy of the trigeminal nerve. A case series.

The incidence of implant-related inferior alveolar nerve injuries (IANI) is steadily increasing within the UK population. This study prospectively reviewed thirty cases (35% male; 65% female) of implant-related IANI seen in a specialist nerve injury clinic.Methods Neurosensory examinations were carried out to ascertain a quantifiable rating of the perception, pain profiling and functional difficulties. Data were analysed using SPSS software. Patients were aware of signing consent forms for the surgery in 11 cases and 8 of those felt they were not explicitly warned about nerve injury. Over 70% of patients were referred after six months post injury. Implant surgery planning involved intra-oral films only (30%), CBCT (10%), dental pantomograph (50%) and long cone peri-apical radiographs (48%). However, no radiographic evidence pre- or postoperatively was provided by the referring practitioner in 15% of cases. Intra-operative problems included bleeding and neurological symptoms. Proximity of the implant bed or implant to the inferior alveolar canal was evident radiographically. This showed contact with roof inferior alveolar nerve canal in 44% of cases, protrusion into the canal in 20% of cases, crossing of the canal in 20% cases and distance in one case, presumed to be due to local anaesthetic injury. All patients presented with a demonstrable neuropathy, which included neuropathic pain (50%) that interfered with speaking, kissing and socialising. Consent, preoperative planning and appropriate referral were inadequate in provision of mandibular implants in this patient group. Recommendations have been proposed to improve practice and possible novel strategies are suggested for the prevention and improved management of these complications.

Unusual cone-beam computerized tomography presentation of traumatic (simple) bone cyst: case report and radiographic analysis

Traumatic (simple) bone cyst (TBC) is an empty nonepithelial-lined cavity of the jaws. The majority of TBCs are located in the body or symphysis of the mandible. Clinically, the lesion is asymptomatic and often discovered incidentally on routine radiographic examination as a noncorticated sharply defined radiolucent area with undulating borders. Because tissues for histologic examination may be scant or nonexistent, the definite diagnosis is invariably achieved during surgery when the lesion is empty. In this report, we present a case of unusual bilateral synchronous TBCs of the mandible with possible traumatic etiology, featuring significant buccolingual expansion of the mandibular ramus and body, presence of septa, and probable displacement of the inferior alveolar canal.

Evaluation of Dimensional Accuracy of Panoramic Cross‐Sectional Tomography, Its Ability to Identify the Inferior Alveolar Canal, and Its Impact on Estimation of Appropriate Implant Dimensions in the Mandibular Posterior Region

To evaluate the dimensional accuracy of panoramic cross-sectional tomography, its impact on implant size estimation and its ability in identifying the inferior alveolar canal in the mandibular posterior region. Eight partially edentulous mandibles with 18 edentulous sites were obtained. Orthopantomograms and tomograms were made and the mandible's outline and the position of mandibular canals on tomograms were traced on a clear acetate paper. Horizontal and vertical magnification factors were calculated. The mandibular height, distance between mandibular canal and alveolar crest, maximum bucco-lingual width, distance between buccal cortex and mandibular canal, and cortical thickness at the inferior border of the mandible were measured. Potential implant sites were identified and implant sizes were estimated. Location and visibility of mandibular canals were also evaluated. The mandibles were sectioned at each site and all the above mentioned parameters were assessed which served as gold standard. Mean horizontal and vertical magnification factors were 1.47 ± 0.048 and 1.53 ± 0.038. Total height and maximum bucco-lingual width were underestimated by 1.88% and 1.59%. Crest to canal distance, cortical thickness at the inferior border of the mandible and buccal cortex to mandibular canal were overestimated by 0.59%, 5.16%, and 3.64%. Implant sizes were estimated for 11 sites and changes were recorded at 2 sites between record 1 and record 2. However, there was no disagreement between record 2 and record 3. Of the canals, 61.11% were located lingually and the visibility of mandibular canals was poor in 44.44% of cases. The tomograms were found to be accurate for the measurements in both horizontal and vertical planes and reliable for implant size estimation, taking into consideration proper magnification factors. They were also found to be useful in assessing the location of mandibular canal but were not very effective in discerning it.

Evaluation of the Inferior Alveolar Canal for Cysts and Tumors of the Mandible—Comparison of Multidetector Computed Tomography and 3-Dimensional Volume Interpolated Breath-Hold Examination Magnetic Resonance Sequence With Curved Multiplanar Reformatted Reconstructions

To evaluate the mandibular canal using volume interpolated breath-hold examination (VIBE) sequencing in patients with cysts and tumors of the mandible. Twenty-five patients with mandibular cysts and tumors were recruited for a study in the authors' institution to compare the role of multidetector row computed tomography with magnetic resonance imaging (MRI) in jaw lesions. Of these 25 patients, VIBE was performed in 12 patients (age range, 16 to 52 yrs; 11 male and 1 female patients) and formed the study group. The status (normal/destroyed/attenuated) and position of the inferior alveolar canal (normal/displaced) on panoramic reconstructed computed tomographic (CT) images and curved multiplanar reformatted (MPR) images reconstructed from VIBE images were analyzed. The contralateral normal mandibular canal was used as the control in these patients. In all 12 patients, the inferior alveolar canal on the normal side was visualized as a hyperintense structure in relation to the hypointense bone on the curved MPR VIBE images. In 9 patients, the inferior alveolar canal was equally well visualized on panoramic CT and curved MPR VIBE images. In 2 patients, the inferior alveolar canal was better visualized on curved MPR VIBE images; in 1 patient, the course of the mandibular canal was better seen on panoramic CT images. MR reconstructions with VIBE sequencing as source images provide images comparable to CT reconstructed images for evaluation of the mandibular canal. Three-dimensional (3D) VIBE sequencing can be added to the MR protocol to visualize the inferior alveolar neurovascular bundle. 3D VIBE sequencing increases the diagnostic capabilities of MRI when used to image mandibular cysts and tumors.