Morphological assessment of the anterior loop of the mandibular canal in Koreans

The alveolar canals and foramina in the first edition of Terminologia Oroanatomica: a preview

Anatomy was initially developed out of necessity to decrease surgery complications. Over time, anatomists and surgeons have sometimes used different terms for the same anatomical structures, thus resulting in numerous discrepancies in terminology between anatomy and surgery. To avoid any confusion or misunderstanding and to better elucidate the oral anatomy terms, the Federative International Programme for Anatomical Terminology (FIPAT) organized a group of specialists on oral anatomy, Terminologia Oroanatomica (ToA) working group, composed of dentists, anatomy researchers, anatomy educators, oral and maxillofacial surgeons, and oral and maxillofacial radiologists. Within the ToA working group, major anatomical structures in the mandible, such as the mandibular canal, were focused and discussed to determine the most appropriate term, i.e., inferior alveolar canal. Although yet to be approved by the International Federation of Associations of Anatomists (IFAA), this article will preview some changes suggested by the ToA.

Prevalence, length, and patterns of Anterior Loop among the South Indian population: A comparative study between Panoramic Radiography and Cone Beam Computed Tomography

Purpose

To assess the prevalence, length, and patterns of the anterior loop of the inferior alveolar nerve by panoramic radiography and cone beam computed tomography (CBCT).

Materials and Methodology

A prospective study was conducted on 300 mental foramen regions by exposing them to panoramic radiography and CBCT scan. Two individual observers evaluated the images to assess the presence of an anterior loop, the mean length of the loop, and the most frequent pattern of the loop in our population.

Result Analysis

The prevalence of the anterior loop for male patients and female patients by panoramic radiography was 34% and 32% on the right side and 30% and 36% on left side, respectively. By CBCT, the corresponding values were 69% and 72% on the right and left side, respectively, for male patients, and 73% and 81% on the right and left side, for female patients, respectively.

Conclusion

The results from our study strongly emphasize the need for CBCT imaging before planning for procedures in the mental foramen region because the prevalence, length, and pattern of loop significantly varies with respect to age, sex, and population.

A New Concept of Narrowing Genioplasty: Home Plate-Shaped Sliding Osteotomy

BACKGROUND

Narrowing genioplasty is commonly performed among East Asian populations, as a broad and/or square chin can be aesthetically unappealing. This study was aimed to introduce the home plate-shaped sliding osteotomy technique for narrowing genioplasty and to evaluate the results of this technique.

METHODS

A retrospective chart review of 117 patients who underwent home plate-shaped sliding osteotomy alone between 2011 and 2019 was performed. The angles of oblique osteotomy lines and measurements of caudal repositioning, which significantly affect the postoperative chin shape, were evaluated.

RESULTS

The home plate-shaped sliding osteotomy technique was successfully accomplished for narrowing genioplasty as an isolated procedure. The mean distance of caudal repositioning was 3.9 ± 0.8 mm, and the mean angles of oblique osteotomy lines were 23.3 ± 4.8 degrees on the right and 21.8 ± 3.5 degrees on the left. This produced an aesthetically pleasing rounded and proportionately narrow chin. The incidence of minor complications was 6.0 percent. There were no major complications. In particular, the risk of inferior alveolar nerve injury was obviated, as an additional mandibular border osteotomy was not typically used with this technique.

CONCLUSIONS

This new surgical procedure for narrowing genioplasty provides improved aesthetic results by altering the chin shape, rather than reducing the transverse width of the chin. The versatility of this procedure allows the chin shape to be adjusted with respect to narrowing, vertical lengthening, anterior advancement, and asymmetric or cleft chin correction. The present study suggests that home plate-shaped sliding genioplasty may be an excellent alternative for correcting broad and/or square chins and more complex chin deformities.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

A case of inferior alveolar nerve encircling the arteria maxillaris

Here we report a case of inferior alveolar nerve (IAN), which had variability in its formation. IAN was formed by dual roots, which were branching out from the posterior division of mandibular nerve. The observed roots were forming a loop around the pterygoid part of arteria maxillaris (MA). One of the roots was superficial to the MA and the other was deep to it. It is believed that this type of morphological variation in the formation of IAN can have clinial implications, which include compression by adjacent structures and nerve entrapment. The knowledge of this variation is important to anaesthesiologists and dentists, while administering local anaesthesia. This is also enlightening to the maxillofacial surgeons, neurologists and radiologists.

Position of the Mandibular Foramen in Different Facial Shapes Assessed by Cone-Beam Computed Tomography - A Cross-Sectional Retrospective Study

Purpose:

The mandibular foramen, located on the internal surface of the mandibular ramus, is an important anatomical landmark for the success during the inferior alveolar nerve block. This cross-sectional retrospective study aimed to evaluate the location of the mandibular foramen through Cone-Beam Computed Tomography (CBCT) in different facial shapes.

Materials and Methods:

The determination of the location of the mandibular foramen was performed using CBCT of mesocephalic, dolichocephalic and brachycephalic patients (n=40 each). The ramus width (W), the distance from the mandibular foramen to the deepest point of the anterior border of the mandibular ramus (D), the distance from the mandibular foramen to the lowest point of the mandibular notch (V) and the distance from the inferior border of the mandible to the lowest point in of the mandibular border (R), as well as the ratios W/D and V/R, were measured. ANCOVA, two-way ANOVA and Chi-square tests were used to analyze the variation among the facial shapes.

Results:

The ramus width (W) was greater (p<0.0001) in the brachycephalic (28.4±0.5 mm) than in both mesocephalic (26.8±0.36 mm) and dolichocephalic (25.5±0.39 mm) patients. D (p=0.0433) and R (p=0.0072) were also greater in the brachycephalic (17.7±0.36 mm; 43.4±0.75 mm, respectively) than dolichocephalic (16.5±0.3 mm; 40.3±0.63 mm, respectively), but both did not differ from mesocephalic (17.3±0.36 mm; 41.8±0.66 mm, respectively) patients. The other measurements (V, W/D and R/V) did not significantly differ among facial shapes.

Conclusion:

The localization of the mandibular foramen was, in the horizontal direction, more posterior in the brachycephalic patients and, in the vertical direction, higher in the dolichocephalic patients, when compared to the other groups analyzed. Thus, the anatomic data found in this study may help dentists to increase the success of the inferior alveolar nerve block and prevent surgical complications.

Assessment of the anterior loop of the inferior alveolar nerve via cone-beam computed tomography

Objectives

The aim of this study was to evaluate different anatomical variants of the anterior loop of the inferior alveolar nerve (IAN) via cone-beam computed tomography (CBCT).

Materials and Methods

CBCT images of 71 patients (36 males and 35 females) were evaluated. We used the classification described by Solar for IAN evaluation. In this classification, three different types of IAN loops were introduced prior to emerging from the mental foramen. We classified patients according to this system and introduced a new, fourth type.

Results

Type I was seen in 15 sites (10.6%), type II in 39 sites (27.5%), and type III in 50 sites (35.2%). We found a new type in 38 sites (26.8%) that constituted a fourth type.

Conclusion

We found that type III was the most common variant. In the fourth type, the IAN was not detectable because the main nerve was adjacent to the cortical plate and the incisive branch was thinner than the main branch and alongside it. In this type, more care is needed for surgeries including inferior alveolar and mental nerve transposition.

Morphometric study on mandibular foramen and incidence of accessory mandibular foramen in mandibles of south Indian population and its clinical implications in inferior alveolar nerve block

The mandibular foramen is a landmark for procedures like inferior alveolar nerve block, mandibular implant treatment, and mandibular osteotomies. The present study was aimed to identify the precise location of the mandibular foramen and the incidence of accessory mandibular foramen in dry adult mandibles of South Indian population. The distance of mandibular foramen from the anterior border of the ramus, posterior border of the ramus, mandibular notch, base of the mandible, third molar, and apex of retromolar trigone was measured with a vernier caliper in 204 mandibles. The mean distance of mandibular foramen from the anterior border of ramus of mandible was 17.11±2.74 mm on the right side and 17.41±3.05 mm on the left side, from posterior border was 10.47±2.11 mm on the right side and 9.68±2.03 mm on the left side, from mandibular notch was 21.74±2.74 mm on the right side and 21.92±3.33 mm on the left side, from the base of the ramus was 22.33±3.32 mm on the right side and 25.35±4.5 mm on the left side, from the third molar tooth was 22.84±3.94 mm on the right side and 23.23±4.21 mm on the left side, from the apex of retromolar trigone was 12.27±12.13 mm on the right side and 12.13±2.35 mm on the left side. Accessory mandibular foramen was present in 32.36% of mandibles. Knowledge of location mandibular foramen is useful to the maxillofacial surgeons, oncologists and radiologists.

Study of the mandibular incisive canal anatomy using cone beam computed tomography

PURPOSE

The aim of this study was to identify the range of individual variability in dimensions and topography of the mandibular incisive canal (MIC) in vivo.

METHODS

One hundred cone beam computed tomography (CBCT) scans of patients from dental outpatient hospitals of Minsk, Belarus were performed on Galileos GAX5 using standard exposure and patient positioning protocol. Reformatted panoramic and sagittal CBCT images were analyzed.

RESULTS

The MIC was visualized in 92% of CBCT images. It was detected in the first premolar root region in 93% of cases, and only in 21% of cases it reached the central incisors root area. The MIC started prior to the mental foramen opening with formation of the anterior mental loop in 48% of cases. The MIC started at the level of the mental foramen or close to it in 52% of cases. The degree of MIC visibility and its internal vertical diameter decreases when it comes closer to the midline of the mandible. The distance from the roots of teeth to the upper wall of MIC increases in the mesial direction, while the position of MIC in relation to the base of the mandible remains virtually unchanged.

CONCLUSIONS

The MIC can appear in a different length and can reach the level of the root of the central mandibular incisor. Individual topography of MIC should be determined during the preoperative radiological examination and surgical procedures in the anterior region of the mandible.