Do anatomical variations of the mandibular canal pose an increased risk of inferior alveolar nerve injury after third molar removal?

Application of the "" shaped crown sectioning method in minimally invasive extraction of mandibular horizontally impacted teeth

Mandibular horizontally impacted horizontally impacted teeth (MHIT) often require extraction due to complications such as pericoronitis, caries, and periodontal disease. This study explores the efficacy of the "" shaped crown sectioning method for these extractions. From May 2021 to May 2023, 240 patients undergoing extraction of MHIT were randomly and double-blindly assigned to the study group. (n = 120) using a micro-power system or the control group (n = 120) using an ultrasonic instrument. Key outcomes measured included operation time, alveolar damage, postoperative pain (VAS), mouth opening degree, and wound healing. The study group showed shorter operation times, lower alveolar damage scores, lower VAS scores, greater mouth opening degrees, and better wound healing than the control group (P < .05). The "" shaped crown sectioning method significantly reduces buccal alveolar bone removal, operation time, alveolar damage, and postoperative pain while improving mouth opening and wound healing, demonstrating substantial clinical value.

Is the presence of accessory mandibular canals associated with the dimensions of the mandibular canal?

AIM

The aim of this study is to classify accessory mandibular canals (AMC) and investigate their association with the dimensions of the mandibular canal (MC) to enhance surgical planning and prevent complications in dental treatments.

METHODS

Cone-beam computed tomography (CBCT) images were evaluated. AMC's frequency, length, and diameter, including dental, superior, inferior, forward-open, forward-closed, and retromolar types, were determined. Additionally, the dimensions of the MC, including its length and diameter, were measured, and the relationship between the AMC and MC was statistically analyzed. Descriptive statistics, chi-square test, independent samples t-test (for normally distributed data), Kruskal-Wallis test (for non-normally distributed data), and Tamhane post hoc test were used for statistical analysis of the data.

RESULTS

AMC was identified in 82 of the 222 hemimandibles examined (36.9%). It was found that the length and diameter of AMCs varied significantly depending on the AMC type (p = 0.000). The diameter of the dental type AMCs (mean 0.40 ± 0.22 mm) was considerably smaller than that of other AMC types (mean 0.86 ± 0.37 mm). The length and diameter of the MC were measured as 69.20 ± 5.10 mm and 2.96 ± 0.57 mm, respectively. While MC length was not found to influence the presence of AMC (p = 0.785), MC diameter was significantly associated with the occurrence of AMC (p = 0.000).

CONCLUSIONS

AMC, which is critical for improving surgical planning and reducing the risk of complications in dental procedures, is not uncommon. Their presence should be carefully evaluated, particularly in cases where the MC has a larger diameter.

Comparison of two surgical techniques for the extraction of mandibular horizontally impacted third molars near the mandibular canal: the displacement reduction method and the away-from-nerve method

OBJECTIVES

To introduce two surgical techniques for extracting horizontally impacted wisdom teeth near the mandibular nerve canal and to assess their effectiveness.

MATERIALS AND METHODS

This study involved patients requiring extraction of horizontally impacted wisdom teeth near the mandibular canal from January to December 2024. Cases were grouped into three categories: close, compressing, and intruding into the mandibular canal. Depending on the tooth's position relative to the nerve canal, it was classified as lingual, middle, or buccal. Extractions were carried out using either the displacement reduction technique or the away-from-nerve method. Surgical time, postoperative swelling, VAS index, and inferior alveolar nerve injuries were documented.

RESULTS

The displacement reduction technique was selected for 50 cases, and the away-from-nerve method for another 50. Among the teeth that contacted the mandibular nerve canal, 80% chose the away-from-nerve method, and among teeth intruding into the nerve canal, 93.1% opted for the displacement reduction technique. When the canal was lingual to the tooth, 81.5% chose the displacement reduction technique, and when buccal, only 23.7% did so (p < 0.05). The displacement reduction technique resulted in a mean surgical time of 15.38 ± 4.35 min, significantly shorter than the away-from-nerve method (12.10 ± 3.60 min, p < 0.05). Patients underwent the displacement reduction technique had lower VAS scores (p < 0.05) and less swelling (p < 0.05). Among all patients, 3 suffered postoperative nerve injuries.

CONCLUSION

Both techniques are viable for extracting horizontally impacted wisdom teeth near the mandibular canal, with minor postoperative reactions and a low risk of postoperative nerve injury.

CLINICAL RELEVANCE

Both surgical techniques for extracting impacted wisdom teeth near the mandibular canals reduce postoperative complications and the risk of nerve injury.

Does low bone mineral density have an association with head and neck soft tissue calcifications?

OBJECTIVES

To evaluate whether low bone mineral density (BMD) has an association with the presence of head and neck soft tissue calcifications (STC), aging, and impaired mandibular canal cortices visibility.

MATERIALS AND METHODS

Panoramic radiographs of 1000 women aged between 50 and 75 years old were evaluated by two examiners to classify BMD using mandibular cortical index (C1- normal, C2-moderately eroded and C3-severely eroded), the presence of STC, and also the mandibular canal cortices visibility at the ramus region. Chi-square test evaluated the association between the variables (α = 5%).

RESULTS

There was no association between bone loss and the presence of head and neck soft tissue calcifications, except for calcified thyroid cartilage, which was less visualized at C3 group than others (p < 0.05). Women aged 61 to 70 years old presented higher bone loss than those between 50 and 60 (p < 0.05). The mandibular canal was more poorly visualized at C3 group than C1 and C2 (p < 0.05).

CONCLUSIONS

In general, no association between BMD and the presence of STC was found. However, greater bone loss had a positive correlation with aging and impaired mandibular canal cortices visibility.

CLINICAL RELEVANCE

No relationship between bone mineral density and the existence of soft tissue calcifications was found. Nevertheless, increased bone loss was positively associated with aging and a reduced mandibular canal cortices visibility. This finding highlights the clinical importance of considering bone density factors when planning treatment strategies for patients with related disorders.

Automated segmentation of the mandibular canal and its anterior loop by deep learning

Accurate mandibular canal (MC) detection is crucial to avoid nerve injury during surgical procedures. Moreover, the anatomic complexity of the interforaminal region requires a precise delineation of anatomical variations such as the anterior loop (AL). Therefore, CBCT-based presurgical planning is recommended, even though anatomical variations and lack of MC cortication make canal delineation challenging. To overcome these limitations, artificial intelligence (AI) may aid presurgical MC delineation. In the present study, we aim to train and validate an AI-driven tool capable of performing accurate segmentation of the MC even in the presence of anatomical variation such as AL. Results achieved high accuracy metrics, with 0.997 of global accuracy for both MC with and without AL. The anterior and middle sections of the MC, where most surgical interventions are performed, presented the most accurate segmentation compared to the posterior section. The AI-driven tool provided accurate segmentation of the mandibular canal, even in the presence of anatomical variation such as an anterior loop. Thus, the presently validated dedicated AI tool may aid clinicians in automating the segmentation of neurovascular canals and their anatomical variations. It may significantly contribute to presurgical planning for dental implant placement, especially in the interforaminal region.

Monitoring cone-beam CT radiation dose levels in a University Hospital

OBJECTIVE

To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age.

METHODS

An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes.

RESULTS

A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction.

CONCLUSIONS

Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

Bifid Mandibular Canal: A Proportional Meta-Analysis of Computed Tomography Studies

Introduction

Growing body of evidences showed different grades in prevalence of bifid mandibular canals. Because the previous reviews focused solely on patient-level occurrence, hemi-mandible-level prevalence, bilateral symmetry, length, and diameter of bifid mandibular canals were required to be estimated collectively. The research question of this meta-analysis was "What is the prevalence of bifid mandibular canal among patients seeking computed tomography examinations"?

Materials and Methods

In vivo, computed tomography, and cross-sectional studies were eligible. Studies, with less than 100 subjects or anatomic site restriction or controlled class of bifid mandibular canal, were excluded. Joanna Briggs Institute (JBI) critical appraisal tool for prevalence studies was used to assess methodological quality of all included studies. Random effect meta-analyses for proportion of bifid mandibular canal were done.

Results

40 studies met the inclusion criteria. All studies were selected for both systematic review and meta-analyses. Totally, 17714 patients and 31973 hemi-mandibles were included. All eligible studies showed moderate risk of bias on average. Resulting from the random effect model, more than 20% of patients seeking computed tomographic examinations had bifid mandibular canals (BMCs) which penetrated into slightly more than 14% of hemi-mandibles. Of the patients having bifid mandibular canals (BMCs), nearly 23% exhibited such anatomy on both sides of their mandibles. Estimated mean length and diameter of the accessory canals of bifid mandibular canals were 12.17 mm and 1.54 mm, respectively.

Conclusion

The geographical locations, classifications, reliability test, and voxel size of computed tomography were all implicated in the prevalence of bifid mandibular canals along with gender and laterality, although considerable heterogeneity and bias were detected.