Search Results (19)

Background/Objective: This study aimed to determine the position of the mylohyoid ridge (MR) and lingual concavity (LC) in the mandible and their relationship with the mandibular canal (MC) and submandibular fossa, to provide anatomical guidance for surgical procedures in this region. Methods: A retrospective analysis was performed on cone beam computed tomography (CBCT) scans from 200 adult patients who had undergone imaging for dental treatment. On cross-sectional images at the level between the first and second molar roots, the following measurements were obtained: LC horizontal depth, LC height, LC depth, MR height, MR depth, and the distances from MR to MC (MR–MC) and LC to MC (LC–MC). Results: Mean values were: LC horizontal depth: 3.72 ± 0.90 mm, LC height: 11.74 ± 2.01 mm, LC depth: 12.54 ± 3.03 mm, MR height: 17.66 ± 2.60 mm, MR depth: 6.87 ± 2.38 mm, MR-MC: 8.30 ± 2.00 mm, and LC-MC: 3.72 ± 0.87 mm. All parameters were symmetrical between the right and left sides of the mandible, with no significant sex differences. The positions of the MR and LC were related to each other, and the position of the MC was related to the positions of the LC and MR. There was no correlation between the horizontal depth of the LC and the position of the MR, LC and MC. Conclusions: The vertical positions of the MR and LC are related to each other and MC. Therefore, it can be used as a landmark in implant surgery. Full article

Background and Objectives: The extraction of mandibular third molars poses challenges due to their proximity to the mandibular canal and risk of inferior alveolar nerve (IAN) injury. Accurate preoperative evaluation is essential to minimize complications. This study assessed the three-dimensional positional relationship between the mandibular canal and lower third molars using cone-beam computed tomography (CBCT), aiming to identify anatomical positions associated with increased surgical risk. Materials and Methods: This retrospective study analyzed 253 CBCT scans of fully developed lower third molars. The mandibular canal position was classified as apical (Class I), buccal (Class II), lingual (Class III), or interradicular (Class IV). Contact was categorized as no contact, contact with a complete or defective white line, or canal penetration. In no-contact cases, the apex–canal distance was measured. Statistical analysis included descriptive and contingency analyses using the Chi-Square Likelihood Ratio test. Results: Class I was most common (70.8%) and presented the lowest risk, while Classes III and IV showed significantly higher frequencies of canal contact or penetration. Class II exhibited shorter distances even in no-contact cases, suggesting residual risk. Statistically significant associations were found between canal position and both contact type (p < 0.001) and apex–canal distance (p = 0.046). Conclusions: CBCT offers valuable insight into the anatomical relationship between third molars and the mandibular canal. High-risk positions—particularly lingual and interradicular—require careful assessment. Even in the absence of contact, close proximity may pose a risk and should inform surgical planning. Full article

Background: This is a systematic review on the subject of anatomic landmarks and variations in the mandible that influence implantation placement. With this systematic review, we would like to summarize the results from different studies that are relevant to this subject and that are up to date, presenting their main findings, the measurements of mentioned landmarks, and giving clinical implications that will be helpful to practitioners in their better understanding of this topic. Methods: This study followed all of the elements of PRISMA. The criteria for inclusion and exclusion are described in detail. The following bibliographic databases were searched: PubMed (MEDLINE), The Cochrane Library, Wiley Online Library, EMBASE, and, additionally, Google Scholar. The search of articles was carried out using a combination of different keywords with a Boolean operator for each keyword. A total of 30 studies were included in this review and the risk of bias for each study was assessed. This review was registered with the PROSPERO ID number CRD42024609308. Results: The structure “SPIDER“ was used to present the findings in the summation table, followed by a detailed description of the quantitative findings and overall mean values of the most commonly used measured points. The morphometric measurements of anatomic details and variations in the mandible, such as the mandibular canal, mental foramen, lingual foramina, lingual canal, incisive canal, and mandibular concavity, are of high significance for clinicians dealing with implantation where gender, ethnicity, age groups, the side of the mandible, or remaining teeth can influence implantation planning. Conclusions: The distances of the named anatomic landmarks to the surrounding bone structures that are used as a guide during planning are of huge importance, so proper and detailed measurements must be executed by experienced professionals using CBCT. Knowledge of the position and variation in these landmarks may be used for any bone-guided augmentation, surgical transpositions of anatomic landmarks, and surgery intervention planning. The results of this study can aid in choosing appropriate measurement points and give the gross picture, for clinicians, in therapy planning, considering all the landmarks of significance in the mandible. Full article

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. Full article

Background: The distinction between where the pulp chamber ends and the root canal system begins is poorly defined within the existing literature. Methods: This paper aimed to describe a range of accurate methods to define the transition from pulp chamber to root canal in different first molar root morphologies using micro-focus computed tomography (micro-CT). Methods: The sample consisted of 86 mandibular and 101 maxillary first molars from the skeletal collections housed in the Department of Anatomy and Histology of the Sefako Makgatho Health Sciences University and the Pretoria Bone Collection. A stepwise approach using the cemento–enamel junction (CEJ) and dedicated landmarks was followed to create an automated cross-sectional slice. Results: Transition from pulp chamber to root canal could be accurately determined on maxillary and mandibular teeth. The occurrence of two separate roots in mandibular molars was 97.7%, with the remaining 2.3% having an additional disto-lingual root, with no mandibular molars displaying fused roots. In the maxillary molars, 92.1% had three separate roots and 7.9% displayed root fusion. Within this group, one tooth displayed a C-shaped root canal configuration and one a mesotaurodont-type morphology. Conclusion: The suggested methodology to determine orifice location was found to be appropriate in all morphological types. Full article

Background: The remaining dentinal thickness is a significant factor to deal with when planning post-endodontic treatment. Aim: To assess the changes in the root canal dentinal thickness of intact and endodontically treated teeth using CBCT scans in the coronal, middle, and apical third of the root canal. Material and methods: Three hundred CBCT scans for three age groups were analyzed to study the dentinal thickness pre- and post-endodontic treatment. The dentinal thickness (DT) was measured along the buccal, mesial, distal, and lingual/palatal walls from the inner surface of the root canal to the outer surface in mm. Statistical analysis was set at 0.05. Results: The results of this study showed that the buccal, palatal, distal, and mesial dentinal thickness in intact and endodontically treated teeth is different. The differences were statistically significant when comparing the parameters of “healthy” and “treated” teeth (p < 0.05). There were no statistically significant differences in indicators associated with age (p > 0.05). In the coronal third of the root canal, the least amount of dentin tissue lost was 4.2% for mandibular canines. Conclusions: The dentinal thickness in the coronal and middle third of the root decreases significantly more than the apical third. The most loss of dentine volume was among molar teeth, and the remaining dentinal thickness was less than 1 mm, which would increase the risk of complication while preparing the canal for a post. Full article

This in vitro study aimed to evaluate the fracture resistance and mode of failure of endocrowns with proximal extension design compared to the conventional design, and to assess the agreement of evaluators on the failure mode. Twenty mandibular third molars free of caries with approximately similar root lengths and crown dimensions were sectioned parallel to the occlusal plane 2 mm above the cementoenamel junction (CEJ). Then, pulp chambers and canals were accessed, cleaned, and smoothed for the path of insertion. To achieve a symmetrical pulp chamber with an average depth of 3 mm, chambers were filled with flowable resin composite. Then, teeth were randomly divided into two groups (n = 10). The control group has all the walls at the same level. The test group had a box extension on the proximal wall 2 mm apical to the buccal and lingual wall level. Endocrowns (n = 20) of two different designs (conventional and proximal extensions) were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein). After cementation, specimens were loaded with a round-end vertical loading tip at a rate of 0.5 mm per minute until fracture (INSTRON, Norwood, MA, USA). Then, the fractured specimens were collected for evaluation and assessment. Statistical analyses were performed using the Mann-Whitney U-test (α = 0.05) for fracture test analysis and Cohen’s Kappa for inter-rater reliability. The Mann-Whitney U-test showed a non-significant difference between the two groups (p = 0.142). However, the mode of failure of the endocrown with proximal extension showed more catastrophic failures than the conventional design. Adding proximal boxes to the endocrown design did not negatively impact the fracture resistance of the restoration. Visualization of the fracture line and tracing their apical end by direct vision or other diagnostic tools is an essential part of the evaluation of failures of endocrowns. Endodontically treated molar teeth with proximal caries extension might be restored with an endocrown with proximal extension. Clinicians should take extra care when visualizing the fracture lines and tracing their apical end as it might be very misleading. Full article

Background: This study aimed to evaluate the midline mandibular lingual canals and foramina and their anatomic variations using CBCT scans. Methods: This study used retrospective analysis. A total of 320 CBCT scans were used to evaluate the study parameters, which comprised the presence or absence of the mandibular lingual foramen (MLF)/mandibular lingual canal (MLC) and its category, the distance between the buccal cortex and the start of the MLC, the distance between the inferior border of the mandible and the superior border of the foramen at its lingual and buccal terminals. The length and diameter of each canal at its lingual and buccal terminals. Results: MLC was found in all included CBCT scans. Out of 320 included CBCT scans, a single canal was represented by 30.9%, double canals (Supra with Infra -spinosum) configuration appeared in 54.7%, and triple canals (Supra-Inter-Infra) represented 14.7%. The supraspinosum canals averaged 5.81 ± 2.08 mm in length and 0.87 ± 0.30 mm in diameter at the lingual terminal. In terms of the number of canals, there was a significant difference between men and women (p ≤ 0.001), with 60% of the men in the sample having double canals and 43.1% of the women having single canals. Moreover, the male gender had a higher prevalence of triple canals (21.3% vs. 8.1%) than females. Males and females were distributed equally among the supraspinosum canals, with no statistically significant difference (p ≤ 0.7). A considerable increase in the finding of interspinosum and infraspinosum canals was seen in the male sample (p ≤ 0.001). Conclusions: midline mandibular canals were found in all investigated CBCTs of the sample of both sexes; however, the anatomy and location of the MLF and canals varied significantly among the Saudi population. Full article

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. Full article

(1) Background: The anatomical variations of neurovascular canals that are encountered in oral surgery are often overlooked by anatomy textbooks or provided with insufficient information. The aim of this study is to analyze the most common variations, describing their morphology, prevalence and clinical implications. (2) Methods: A review of published literature from the 20th century onwards was performed using the PubMed electronic database as well as anatomical textbooks. The variations being investigated were: retromolar canal (RMC) and foramen (RMF), accessory mental foramen (AMF), midline (MLF) and lateral (MLF) lingual foramina and canalis sinuosus (CS). (3) Results: Anatomical variants of neurovascular canals and foramina have a significant incidence and important clinical implications in the most common oral surgery procedures such as third molar extraction, bone harvesting and implantology. (4) Conclusions: Knowledge of these variables is highly important both for students to have a more accurate anatomical awareness and for professional surgeons to be able to provide better diagnoses and prevent complications during oral surgery techniques. Full article

Background: Pre-operative radiographic assessment of the anatomical relationship between the roots of the mandibular third molar and the inferior alveolar nerve (IAN) is a must to minimize the risk of IAN injury during surgery. Objectives: To compare the radiographic signs of digital orthopantomogram (OPG) and cone-beam computed tomography (CBCT). An additional objective was to assess the cortex status between the mandibular canal and third molar on CBCT images in relation to the demographic characteristics, region (right or left side), and angulation of mandibular molar. Methodology: In this retrospective study, a total of 350 impacted mandibular third molars with a close relationship between the inferior alveolar canal (IAC) and impacted mandibular third molars on digital OPG were further referred for CBCT imaging for assessment of the position of the mandibular canal. The study was conducted between August 2018 and February 2020. Digital OPGs were evaluated for radiographic signs like interruption of the mandibular canal wall, darkening of the roots, diversion of the mandibular canal, and narrowing of the mandibular canal. The age and sex of patients, site of impacted third molar, Winter’s classification of mandibular third molar, position of IAC relative to impacted molar, and the radiographic markers of OPG were assessed for cortical integrity using CBCT. Chi square testing was applied to study the values of difference and binomial logistic regression was done to assess the factors associated with cortication. Statistical significance was set at p ≤ 0.05. Results: Among 350 patients, 207 (59.1%) were male and 143 (40.9%) were female with a mean age of 36.8 years. The most common OPG sign was interruption of white line, seen in 179 (51.1%) cases. In total, 246 cases (70.3%) showed an absence of canal cortication between the mandibular canal and the impacted third molar on CBCT images. Cortication was observed in all cases with a combination of panoramic signs which was statistically significant (p = 0.047). Cortication was observed in 85 (50.6%) cases where IAC was positioned on the buccal side, 11 (16.9%) in cases of inferiorly positioned IAC, and just 8 (7.6%) for cases of lingually positioned IAC which was statistically significant (p = 0.003). Statistically insignificant (p > 0.05) results were noted for cortex status in CBCT images with regards to the age, sex, site, and angulation of impacted third molars. Conclusion: CBCT imaging is highly recommended for those cases where diversion of the mandibular canal is observed on OPG and when the roots are present between canals. Full article

The aim of this study was to compare the alveolar bone crest (ABC) level of root canal filled (RCF) teeth without apical periodontitis with corresponding non-filled teeth in the same individual using three-dimensionally cone-beam computed tomography (CBCT) data. Two hundred and thirty-five matching pairs of RCF teeth and corresponding teeth without RCF were selected from a pool of 580 random CBCT-images (voxel size 160–200 µm). Teeth with apical periodontitis, perio-endodontic lesions or surgical endodontic treatment were excluded. The distance between the cemento–enamel-junction (CEJ) and the ABC was assessed centrally mesial, distal, palatal/lingual and buccal at each tooth (∑1880 measuring points) in a standardized manner. Topographic, gender, and age-related relationships were also noted. Data were analyzed using the Kruskal–Wallis-test. The ABC-level between RCF teeth (2.64 ± 1.25 mm) and teeth without RCF (2.61 ± 1.16 mm) did not differ significantly (p > 0.05). No differences concerning localization (maxilla/mandible, tooth type) and gender (p > 0.05) occurred. Overall, ABC-level in the maxilla (2.74 ± 1.48 mm) was significantly lower (p < 0.001) compared to mandibular teeth (2.50 ± 1.41 mm). Patients > 41 years had significantly lower ABC-levels than younger patients (p < 0.05). Men showed a reduced bone level compared to women (p < 0.05). In conclusion, RCF teeth are identical to their non-RCF counterparts, at least in terms of crestal bone level, regardless of the location or type of tooth and the gender of the patient. Thus, root canal treatment is an essential pillar for long-term tooth preservation. Full article

The aim of the present study was to assess the positive predictive value (PPV) of panoramic radiographic signs in the assessment of the relationship between impacted mandibular third molars (IMTMs) and the mandibular canal (MC). This cross-sectional study was conducted by reviewing 102 cone-beam computed tomography (CBCT) and panoramic radiographs of patients with IMTMs and radiographic signs of the contact of the IMTMs with the MC on panoramic radiographs (i.e., root apex darkening and interference with the white line). A positive relationship of the IMTM roots with the MC based on CBCT findings was recorded as the gold standard. The PPV of panoramic radiographic signs was calculated for the detection of the relationship of the IMTM root with the MC. The IMTMs were in contact with the MC on CBCT scans in 90.1% of the cases. The PPV of root apex darkening and the interference with the white line was found to be 89.09% (95% CI: (77.75, 95.88)) and 91.48% (95% CI: (79.62, 97.63)), respectively. The MC had a buccal position in 63.7%, and a lingual position in 35.2%, of the cases. The contact of IMTMs with the MC was more commonly seen in patients with a lingual position (100% of the samples). The IMTM root apex darkening and interference with the white line of the MC on panoramic radiographs had a high PPV for determination of the contact of IMTMs with the MC. Thus, presence of the above-mentioned risk factors indicates the need for subsequent 3D radiographic assessments. Full article

Background: Neurological alterations are one of the main complications occurring after the third molar extractions. The aim of this prospective multicenter cohort study was to find out Cone Beam Computed Tomography (CBCT) features and distribution of neurological complications in patients undergoing lower third molar surgery and to determine the radiological and patient-related factors that could be correlated to the occurrence of inferior alveolar and lingual nerves injury. Material and Methods: 378 patients who underwent lower third molar extraction from March 2018 to March 2019 were included. Clinical and radiological data were collected. CBCT features were recorded following Maglione et al. classification. Symptoms and characteristics of patients who experienced neurological alterations were evaluated. Results: 193 patients needed a second-level radiological exam (CBCT). In these patients, the most common feature was Maglione class 3: a higher frequency of apical or buccal mandibular canals in direct contact with the tooth was observed. 3.17% of the patients developed a neurological complication. Maglione class 4, increased age, and operative time were all positively correlated with neurological alterations. Conclusions: while the buccal or apical position of the mandibular canal was the more common findings, the lingual position was found to have a higher correlation with a negative outcome. Age and operative time were also found to be risk factors for developing nerve injury in the considered population. Full article

Eruption disturbances in permanent mandibular first molars (PM1s) are uncommon. This retrospective study aimed to investigate differences in the position of the mandibular canal in relation to PM1s, with or without, eruption disturbances. Panoramic and cross-sectional views were reconstructed from cone-beam computed tomography imaging of children with PM1 eruption disturbances. Distances from the most inferior margin of the mandible to the center of the mandibular canal (M–C) and from the outer margin of the lingual cortex to the center of the mandibular canal (L–C) were measured for normally erupted PM1s (normal group) and for PM1s with eruption disturbances (ED group) and compared using independent t-tests. The mean M–C was significantly shorter in the ED group (4.86 ± 1.07 mm) than in the normal group (6.56 ± 1.06 mm) (p < 0.05). The mean L–C was also significantly shorter in the ED group (2.74 ± 0.74 mm) than in the normal group (3.09 ± 0.71 mm) (p < 0.05). This study demonstrated that the mandibular canal tended to be positioned more inferiorly in relation to PM1s with eruption disturbances than normally erupted PM1s in children. Clinicians should be aware of this positional deviation when managing children with PM1 eruption disturbances. Full article