Proximity of the Mandibular Canal to Teeth and Cortical Bone

Morphometric Analysis of the Mandibular Canal and Its Anatomical Variants in a Chilean Subpopulation: Cone Beam Computed Tomography Study

The inferior alveolar nerve (IAN), contained within the mandibular canal (MC), is a structure prone to damage in clinical and surgical procedures on the mandible. This study aimed to analyze the MC morphology and its anatomical variants in a Chilean subpopulation using cone beam computed tomography (CBCT). In total, 342 images from patients with the following parameters were observed: 120 kV, 9 mA, field of view 12 × 9 MC, and voxel size 0.12 mm. The average length of the MC recorded a mean value of 70.493 ± 4.987 mm on the right side and 70.805 ± 5.177 mm on the left side. The location of the mental foramen (MF) was most frequently found between the mandibular first and second premolar. The greatest bone thickness was found at the level of the basilar border of the 2MPM. The root closest to the MC was distal from the mandibular second molar. The lowest thickness was in the lingual area at 1MM. The prevalence of the anterior loop (AL) (61.5%) and the retromolar canal (RC) (17.5%) showed no significant differences between men and women. The results obtained showed that the morphology of the MC in the Chilean subpopulation can vary.

Reliability of the AI-Assisted Assessment of the Proximity of the Root Apices to Mandibular Canal

Background: This study evaluates the diagnostic accuracy of an AI-assisted tool in assessing the proximity of the mandibular canal (MC) to the root apices (RAs) of mandibular teeth using computed tomography (CT). Methods: This study involved 57 patients aged 18-30 whose CT scans were analyzed by both AI and human experts. The primary aim was to measure the closest distance between the MC and RAs and to assess the AI tool's diagnostic performance. The results indicated significant variability in RA-MC distances, with third molars showing the smallest mean distances and first molars the greatest. Diagnostic accuracy metrics for the AI tool were assessed at three thresholds (0 mm, 0.5 mm, and 1 mm). Results: The AI demonstrated high specificity but generally low diagnostic accuracy, with the highest metrics at the 0.5 mm threshold with 40.91% sensitivity and 97.06% specificity. Conclusions: This study underscores the limited potential of tested AI programs in reducing iatrogenic damage to the inferior alveolar nerve (IAN) during dental procedures. Significant differences in RA-MC distances between evaluated teeth were found.

Morphological and topographic evaluation of the mandibular canal and its relationship with the facial profile, skeletal class, and sex

PURPOSE

The aim of this study was to evaluate the morphology and topography of the mandibular canal in patients with different facial profiles, skeletal classes, and sexes.

METHODS

Cone-beam computed tomography volumes of 103 patients were classified according to facial profile and skeletal class. Two examiners classified the mandibular canal into a linear, spoon-shaped, elliptical arc, or turning curvature and measured four related linear distances. The most frequent mandibular canal curvature was identified and multi-way ANOVA with Tukey's test compared the linear measurements between facial types, skeletal class, and sexes (α = 0.05). Kappa and intraclass correlation coefficients were used to assess the reproducibility of qualitative and quantitative variables, respectively.

RESULTS

The examiners showed excellent reproducibility. The four curvatures of the mandibular canal were found, but the spoon-shaped and elliptical arch were the most frequent. No significant differences were observed for most of the linear measurements between the different facial profiles, skeletal classes, and sexes (p > 0.05).

CONCLUSION

Spoon-shaped and elliptical arch are the most frequent curvatures of the mandibular canal; furthermore, its morphology and topography seem to be little influenced by the facial profile, skeletal class, and sex.

Assessment of the Proximity of the Inferior Alveolar Canal with the Mandibular Root Apices and Cortical Plates-A Retrospective Cone Beam Computed Tomographic Analysis

Various endodontic interventions often lead to iatrogenic damage to the inferior alveolar nerve present in the inferior alveolar canal (IAC). The purpose of the present study was to analyze the relationships of IAC with the root apices of mandibular teeth and with the mandibular cortical plates.

MATERIALS

116 cone beam computed tomography (CBCT) scans were examined and the shortest distance of IAC with the root apices of mandibular canines, premolars and molars, and with cortical plates was analyzed. The data were statistically analyzed using SPSS.

RESULTS

The shortest mean distance between IAC and lingual cortical plate (LCP) was found in the third molar area, and between IAC and buccal cortical plate (BCP) in the second premolar area. A high incidence of 60% direct communication (DC) was present in mandibular second molars; 38% in mandibular third molars; 13% in mandibular second premolars; 12% in mandibular first molars; and 1% in mandibular first premolars.

CONCLUSION

Anteriorly, IAC was found to be significantly present in close approximation to the roots of mandibular canines. Posteriorly, IAC was found to be in significant proximity to the distal roots of mandibular second molars.

Assessment of the relationship of the distance between mandibular first and second molars with the inferior alveolar canal and cortical bone plate in an Egyptian subpopulation: a CBCT study

The aim of the current cone beam computed tomography (CBCT) study was to evaluate the proximity of mandibular first and second molar roots to the inferior alveolar canal (IAC) and mandibular cortex in an Egyptian subpopulation. Scans of 120 patients (480 molars, 960 roots) were obtained from the College of Dentistry database at the Suez Canal University, Egypt. Buccal and lingual bone plates and root thickness were measured at the specified resected root end 3 mm from the radiographic apex, and so was the proximity of the root apices to the IAC. Measurements of the right and left mandibular first and second molars were recorded for each root. Three examiners performed the measurements separately. ANOVA was used to compare the different roots. Bonferroni's post-hoc test was used for pair-wise comparisons when ANOVA was significant. The significance level was set at p ≤ 0.05. The findings displayed a closer proximity of the mandibular second molar apices to the IAC, as compared to the mandibular first molars. The mesial roots were at a shorter distance than the distal ones. Moreover, the mandibular second molars revealed the thickest total bone width including the root. So, it is beneficial for endodontists to be aware of the relation of the mandibular first and second molars to the surrounding cortical bone plates and the IAC before starting either nonsurgical or surgical endodontic treatment.

The influence of age, sex, and tooth type on the anatomical relationship between tooth roots and the mandibular canal

Purpose

Cone-beam computed tomography (CBCT) reconstructions were analysed to elucidate factors affecting the anatomical relationship between tooth roots and the mandibular canal(MC).

Materials and Methods

Images of 300 volumetric tomography scans of patients aged between 20 and 79 years old (167 women and 133 men) were analysed. The mean distances between 2,053 dental root apices and the internal border of the MC were obtained by measuring the horizontal and vertical distances on coronal CBCT images. The actual distance was then calculated mathematically with the Pythagorean formula. The statistical significance of differences between men and women was assessed using the Mann-Whitney test. Correlations with patient age were evaluated with the Spearman rank correlation coefficient.

Results

The mean distances ranged from 2.17 mm, for single right third molar roots in women, to 8.02 mm for single left third molar mesiolingual roots in men. The mean distances measured for the mandibular right second molar mesial roots and the right second premolar roots were larger in men than in women. Age showed a significant positive correlation with the measured distances for mesial and distal roots of the first and second molar on both sides and the right third molar, mesiolingual roots of the left third molar, and single roots of the right third molar.

Conclusion

The root-to-mandibular canal distance depended on age and the type of tooth. In 2 root types, this distance was impacted by sex.

Mandibular Canal Location and Cortical Bone Thickness in Males and Females of Different Age Groups: A Cone-beam Computed Tomography Study

AIM: The purpose of the study was to measure and compare the prevalence of mandibular canal (MC) location variations in regard to mandibular first molars in both genders at different age groups. METHODS: A retrospective study was performed on 80 cone-beam computed tomography scans. Distance between MC and apical apices of first molars, buccal and lingual cortical plates was measured in both sides. RESULTS: 80 scans with 160 sides were analyzed. Distances was measured bilaterally for all scans with mean (5.22 ± 0.77) in men versus (4.1 ± 0.7) in women at group age 31–40 apical to apices of first molars. The mean was (3.77 ± 0.62) in men versus (2.81 ± 0.47) in women at same age group at buccal side, lingually the mean was (4.02 ± 0.67) in men versus (3.67 ± 0.26) in women in the same age group. CONCLUSION: Our study showed that there were decrease in measurements in older age group in both genders and in female groups more than male groups but with no statistical significant difference.

An Update on Endodontic Microsurgery of Mandibular Molars: A Focused Review

Endodontic microsurgery is a highly predictable treatment option in most cases when conventional endodontic treatment is not feasible. Nevertheless, mandibular molars are still considered by clinicians to be the most difficult type of teeth, with the lowest success rate. In recent years, endodontic microsurgery has been attempted more frequently with the emergence of modern cutting-edge technologies such as dental operating microscopes, various microsurgical instruments, and biocompatible materials, and the success rate is increasing. This review describes the current state of the art in endodontic microsurgical techniques and concepts for mandibular molars. Notably, this review highlights contemporary equipment, technology, and materials.

Computed Tomography for the Assessment of the Potential Risk After Implant Placement in Fresh Extraction Sites in the Posterior Mandible

Immediate implant placement (IIP) is considered a reliable procedure, with survival rates of 94.9%-98.4%. Nevertheless, in the posterior mandible, it poses a high risk of damage to anatomic structures. The aim of this study was to determine the risk of anatomic structures injury associated with IIP in the posterior mandible based on apical primary stability, respecting a safe distance from the inferior alveolar nerve and lingual plate, and to evaluate the influence of different factors on those risks. Pre-extraction cone beam computed tomography scans of 100 patients were retrospectively analyzed. Measurements were taken from tooth apices to lingual plate and to mandibular canal. Values of <4 mm of the former and <6 mm of the latter were categorized as considerable risk. Values of <2 mm at both measurements were considered high risk. Two-sided P < .05 was considered statistically significant. Mean root-to-alveolar canal distance was 7.6 ± 2.7 mm in the first molar, 6.5 ± 3mm in the second premolar, and 5.4 ± 3 mm in the second molar (P < .005). The mean distance to the outer lingual cortex was 3.9 ± 2.1 mm in the first molar and 3.2 ± 0.1 mm in the second molar. Thus, second molars were at higher risk of inferior alveolar nerve injury and lingual plate perforation during IIP. Background factors associated with higher IIP risk were female sex and age < 40 years. In the mandible, the anatomic risk posed by IIP is greatest for second molars and lowest for first molars. Several background factors affect the distances between root apices and the mandibular canal.

Do positional changes of the inferior alveolar canal after sagittal split mandibular osteotomy affect neurosensory recovery?

The purpose of this study was to assess the pre- and postoperative position and dimensions of the inferior alveolar canal (IAC) following sagittal split osteotomy (SSO) and identify any association with postoperative neurosensory deficit (NSD) at 1 year. This retrospective cohort study enrolled consecutive patients who had SSO performed to correct skeletal malocclusion. The pre- and postoperative cone beam computed tomography data were superimposed to visualize differences in IAC position and dimensions. Subjective and objective neurosensory tests were used to determine NSD in the inferior alveolar nerve distribution. A total of 20 subjects were included. The preoperative distance from the lateral cortex of the IAC to the inner aspect of the lateral cortex of the mandible was significantly greater in sides with NSD when compared to sides without NSD (P =  0.01). A significantly greater reduction in the postoperative distance measurement was seen in sides with NSD when compared to sides without NSD (P =  0.01). The magnitude of mandibular movement was significantly increased in sides with NSD (P = 0.02). The preoperative location of the IAC, as well as certain changes in the mediolateral and vertical positions as a result of SSO, are risk factors for postoperative NSD.

The anatomical relationship between the roots of erupted permanent teeth and the mandibular canal: a systematic review

PURPOSE

This study reviewed the literature on the position of the mandibular canal (MC) relative to the root apices (RA) of neighbouring teeth using cone beam computed tomography (CBCT).

METHODS

The authors searched the PubMed, Scopus, EBSCO Dentistry and Oral Sciences Source, Cochrane and Lilacs databases for relevant English-language articles with no year limitations published through January 25, 2018.

RESULTS

The search identified 888 articles, 12 of which met the inclusion criteria. Three groups were found based on the measuring method: the shortest distance from the RA to the MC, the vertical distance from the RA to the MC, or the distance from the RA to the superior cortical bone of the MC. In the first and second groups, the shortest distances to the canines, first premolars, second premolars, first molars, second molars, and third molars were 3.8 mm, 4.76 mm, 1.65 mm, 1.23 mm, 0.64 mm, and 1.28 mm, respectively. In the third group, the shortest distances to the second premolars, first molars, and second molars were 2.71 mm, 3.82 mm, and 1.4 mm, respectively.

CONCLUSIONS

The distance from the MC to the RA was generally shorter in females and younger people, with decreasing distances in patients over 60 years old, and depended on the tooth type.

TRIAL REGISTRATION

The protocol for this systematic review was registered on PROSPERO (CRD42018085478).

Inferior alveolar nerve canal position in relation to mandibular molars: A cone-beam computed tomography study

Objective

This study was carried out to prevent the risk of iatrogenic injuries to the inferior alveolar nerve (IAN) canal associated with various surgical interventions in the area of mandibular molars, by using cone-beam computed tomography (CBCT).

Materials and Methods

The present retrospective study was carried out by using CBCT of 100 patients between 18 and 40 years of age group. The linear measurements were made in relation to the 1^st and 2^nd mandibular molars on both the sides. Linear distances between buccal and lingual aspects to the mandibular, buccal, and lingual cortical bone thickness; IAN canal diameter; and the superior corticated border of the IAN canal from the periapex of the 1^st and 2^nd mandibular molars. The statistical evaluation was done using SPSS V.20 (SPSS: an IBM company), and P < 0.05 was considered statistically significant.

Results

Both genders of all age groups showed statistically significant result (P < 0.00). All the linear measurements were statistically significant in relation to both the 1^st and 2^nd mandibular molars (P < 0.005), and also the bilateral comparison of the linear measurements showed statistically significant difference in relation to the mandibular 2^nd molar (P < 0.03) and 1^st molar (P < 0.04) among both the sexes.

Conclusion

Clinicians should be aware of the proximity of root apices and cortical plates to the mandibular canal when performing surgical and root canal procedures in the posterior mandible to avoid serious nerve injuries.

Surgical implications of the anatomic situation of the mandibular canal for mandibular osteotomies: a cone beam computed tomographic study

PURPOSE

In bilateral sagittal split osteotomy (BSSO), the risk of lesion of the inferior alveolar nerve (IAN) is important. The aim of this study was to investigate the situation of the IAN in the area of the BSSO in preoperative 158 CBCT.

METHODS

The situation of the mandibular canal (MC) has been studied in six coronal sections (one section each 4 mm) from the proximal root of the second mandibular molar. The height of the MC related to the height of the mandible, and the horizontal distance between the MC and the lateral cortical plate related to the mandibular width have been determined in each section. The cancellous bone width has been measured allowing to determine a cancellous bone ratio.

RESULTS

The variability of the MC was high, depending mainly on the cancellous bone ratio which was higher when the IAN was deep. When a third molar was present, the MC was lower in the area of the third molar.

CONCLUSIONS

To decrease the risk of injuring the IAN in BSSO, the evaluation of the cancellous bone ratio by a preoperative CBCT may be proposed to adapt the surgical technique to the anatomy.

An analysis of the first and second mandibular molar roots proximity to the inferior alveolar canal and cortical plates using cone beam computed tomography among the Saudi population

Objectives:

To evaluate the relationship of the first and second mandibular molar roots to the inferior alveolar canal (IAC) and cortical plates using cone beam computed tomography (CBCT) in the Saudi population.

Methods:

Scans of 60 patients were collected retrospectively from the dental hospital database in King Saud University, Riyadh, Kingdom of Saudi Arabia. Measurements of the right and left first and second mandibular molars for each dental root and the mandibular bone thickness were determined. The position of the IAC was estimated using axial, coronal, and sagittal views. Three examiners performed the measurements independently.

Results:

The mean distance between the root apices of the mandibular molars and the IAC ranged from 1.68-4.79 mm, whereas the mean distance from the outer surface of the buccal cortical plate to the buccal root surface ranged from 2.33-6.72 mm. Similarly, the mean distance from the outer surface of the lingual cortical plate to the lingual root surface ranged from 2.62-4.80 mm. Finally, the mean distance from the outer surface of the lingual cortical plate to the outer surface of the buccal cortical plate was 11.93-13.19 mm.

Conclusion:

The measurements reported in this study may be of value to practitioners treating Saudi patients, as they need to be familiar with the distance of the mandibular first and second molars in relation to the IAC and surrounding cortical plates to accurately assess and plan endodontic surgeries, surgical extractions, and implant placements.

Сross-sectional anatomic study of direct positional relationships between mandibular canal and roots of posterior teeth using cone beam computed tomography

Objectives: To establish the frequency of the various types of direct contacts of the root apices with the wall of the mandibular canal and to determine gender differences in number of such contacts in a selected Belarusian population using cone beam computed tomography. Methodology: One hundred and two cone beam computed tomography scans were analyzed to classify the types of contact and three-dimensional relationship between the mandibular teeth and the mandibular canal. Results: The direct contact between the teeth and the mandibular canal was observed in 63.7% of patients. Overall 300 roots of 189 teeth were in direct contact with the mandibular canal: 9.3% were second premolars, 14.7% were first molars, 33.8% were second molars and 50.0% were third molars. There were no statistically significant differences in the number of teeth with direct contact with the mandibular canal between males and females. Conclusion: The direct contact of the root apices with the mandibular canal was most often found in the second and third molars. The root apices of the third molars had the greatest variability of location relatively to the mandibular canal.

Anatomical position of the mandibular canal in relation to the buccal cortical bone: relevance to sagittal split osteotomy

Objectives

Classification of the degree of postoperative nerve damage according to contact with the mandibular canal and buccal cortical bone has been studied, but there is a lack of research on the difference in postoperative courses according to contact with buccal cortical bone. In this study, we divided patients into groups according to contact between the mandibular canal and the buccal cortical bone, and we compared the position of the mandibular canal in the second and first molar areas.

Materials and Methods

Class III patients who visited the Dankook University Dental Hospital were included in this study. The following measurements were made at the second and first molar positions: (1) length between the outer margin of the mandibular canal and the buccal cortical margin (a); (2) mandibular thickness at the same level (b); (3) Buccolingual ratio=(a)/(b)×100; and (4) length between the inferior margin of the mandibular canal and the inferior cortical margin.

Results

The distances from the canal to the buccal bone and from the canal to the inferior bone and mandibular thickness were significantly larger in Group II than in Group I. The buccolingual ratio of the canal was larger in Group II in the second molar region.

Conclusion

If mandibular canal is in contact with the buccal cortical bone, the canal will run closer to the buccal bone and the inferior border of the mandible in the second and first molar regions.

Correlation between the visibility of submandibular fossa and mandibular canal cortication on panoramic radiographs and submandibular fossa depth on CBCT

BACKGROUND

To identify a correlation between the submandibular fossa (SF) visibility and mandibular canal (MC) cortication on panoramic image and the depth of SF measured on CBCT and also correlation between the depth of SF and vertical and horizontal location of MC on CBCT.

MATERIAL AND METHODS

500 CBCT scans and panoramic radiographs were evaluated. SF depth types were classified as type I (< 2mm); type II (2-3mm) and type III (> 3mm) on CBCT. Visibility of SF and the cortication of MC on panoramic radiographs were compared with the depth of SF on CBCT. Distances between MC and mandibular inferior, buccal and lingual cortices were measured.

RESULTS

No statistically significant correlation was found between radiolucent appearances of SF, cortication of MC, and depth of SF. The deepest part of the fossa was in the second molar area followed by third and first molars. Negative weak correlations were found between B-MC, L-MC distances and depth of SF.

CONCLUSION

Visibility of SF and cortication of MC on panoramic radiographs did not correlate with the depth of SF. A marked radiolucent submandibular fossa on panoramic image does not undoubtedly indicate a deep fossa, which emphasizes the importance of 3-D imaging in implant planning.

A cone-beam computed tomography study of the anatomical relationships between mandibular teeth and the mandibular canal, with a review of the current literature

The purpose of this study was to evaluate age- and sex-related changes in the anatomical relationships between the roots of the molars and premolars and the mandibular canal using cone-beam computed tomography (CBCT) images. A total of 243 patients (116 males, 127 females) aged 16-83 years for whom previous CBCT scans were available were enrolled in this study. The patients were subcategorized by sex and age (Group I, <21 years; Group II, 21-40 years; and Group III, >40 years). The distances between the mandibular canal and the molars and premolars were measured. The mandibular canal was significantly closer to the root apices of the second and third molars than to the apices of other evaluated teeth (p < 0.05). All measurements were significantly higher in male than in female subjects (p < 0.05). Group I subjects exhibited significantly shorter distances between the mandibular canal and root apices of the first and second premolars, and the molars, than those of Group II and III subjects (p < 0.05). Direct contact relationships were found in 1.6%, 3.3%, 3.3%, 16%, and 32.2% of teeth (running from the first premolar to the third molar, respectively). Age and sex influenced the anatomical relationships between mandibular teeth and the mandibular canal, and these should be considered when planning endodontic and surgical procedures to avoid potential nerve injury.

Surgical Approach to Foreign Material Within the Mandibular Canal Due to Iatrogenic Factors

This clinical report describes a relatively infrequent patient with inferior alveolar nerve damage caused by foreign material within the mandibular canal, which is one of the most severe complications of endodontic therapy. Although the circumstance is uncommon, it can have extremely unfavorable consequences for patients, such as anesthesia and paresthesia. In the present case, a patient suffered pain and severe paresthesia in the corresponding area after routine endodontic therapy. Several treatments were conducted to relieve the patient's symptoms, ranging from medication to tooth extraction, but all were of no avail. Ultimately, surgical exploration and debridement were performed with assistance of a customized surgical template. Once the foreign material was excavated, the exacerbation of condition was terminated and gradually reverted. This patient illustrates that special attention is required when undertaking intracanal procedures of lower posterior teeth so as to avoid iatrogenic damage to inferior alveolar nerve. Even more significant, when above-mentioned condition occurs, prompt surgical intervention is essential for recovery of sensation. It also demonstrates the advantages of applying surgical template and piezosurgery in removal of foreign material within the mandibular canal.