Interforaminal Region Research Articles

Assessment of Anatomical Variations in the Anterior Loop of the Mental Nerve in the Northeast Population to Estimate a Safe Zone for Implant Prosthesis: An Institution-Based Study.

The precise location of the anterior loop is of utmost importance during implant surgery to avoid any postoperative complications. The aim of the institution-based study was to determine the prevalence of the anterior loop with respect to age and gender in the northeast population. Sixty outpatients opting for implant prostheses in the interforaminal region of the mandible were enrolled in this study based on the inclusion and exclusion criteria. The anterior loop was identified in 18.3% of the total subjects, and the mean length of the anterior loop was found to be 3.37 ± 0.53 mm. Planning for prosthetic-driven the implant placement was possible in 54.5% of the subjects. Proper treatment planning using cone beam computed tomography (CBCT) with a radiographic stent is paramount important for the safe placement of implant in the presence of the anterior loop of the mental nerve.

Injury Risk Estimation in Mandible-Related Surgical Procedures: A CBCT Study Based on Vital Interforaminal Anatomical Structures.

The mandibular interforaminal region has been considered safe for surgical procedures; nevertheless, the risk of injury to neurovascular structures, such as the mental foramen (MF) and its related structures (anterior loop [AL] and lingual foramina [LF]) should not be overlooked. The study aimed to evaluate the relative risk of injury to these structures during surgical procedures in the anterior region of the mandible based on cone-beam computed tomography (CBCT) scans. A retrospective cross-sectional and observational study was performed on 250 CBCTs from adults (18-69 years) with dentate jaws. Linear measurements of the MF, AL, and LF were evaluated to estimate the risk of injury to these structures during chin-related surgical procedures. The most frequent distance between the base of the mandible (BM) and MF was 8 mm (30.2%). In addition, 20.4% of the CTs had 6 mm from the vestibular cortical bone to the LF. The commonly found measurement from LF to the apex of the nearest tooth was 7 mm (24.0%); 64.2% of the CTs showed a 2-mm distance between the most distal point of the dental implant site to the most anterior point of the AL. Safety distances for genioplasty techniques (MF to mandible base > 6 mm, 96.6% [CI 95%, 95.0%-98.2%]) were observed. Considering the 5-mm cut-off point between the lower limit of a hypothetical bone graft and the chin, 65.4% (CI 95%, 58.9%-71.9%) of CTs were within this distance. Regarding the safety margin of 8 mm, 85.6% (CI 95%, 80.8%-90.4%) were up to this value. This study found safety margins for genioplasty and chin bone grafting surgical techniques that adopt a 5-mm cut-off point. Further similar studies assessing other surgical methods and employing larger samples from different geographical origins may contribute to this field of investigation.

Assessment of the Anterior Loop and Pattern of Entry of Mental Nerve Into the Mental Foramen: A Radiographic Study of Panoramic Images.

The precise location of the mental foramina is an essential landmark in planning the position of dental implants in the anterior mandible. Injury to inferior alveolar nerve during anterior mandibular implant surgery causes altered sensation which greatly affects patient satisfaction. In this study, we assessed the prevalence of anterior loop of mental nerve and the pattern of entry of mental nerve into the mental foramen. Three hundred panoramic radiographs (600 hemimandibles) obtained from records maintained in the Department of Oral Medicine and Radiology were randomly selected for the study. The radiographs were evaluated by two independent observers for the pattern of entry of mental nerve into the mental foramen on either side of the mandible and for the presence or absence of anterior loop of mental nerve. The most prevalent pattern of mental nerve observed was Straight pattern which totals to 67.5% followed by Anterior loop pattern (18.8%) and then the Perpendicular pattern (13.7%). There was no significant association between the gender and subtypes of looping pattern on the left and right side and a highly significant association between the side of the mandible and loop pattern was observed by Chi square test. The Anterior loop pattern of mental nerve has been found in 18.8% of the population suggesting to accurate planning with three-dimensional imaging techniques to avoid injury to mental nerve during dental implant placement and other surgical procedure involving the interforaminal region of the mandible.

The Anatomy of the Mandibular Incisive Canal and Its Influence in Implant Therapy: A Scoping Review.

The interforaminal region is considered more favorable for implant placement than the posterior mandible in edentulous patients, mainly because the inferior alveolar nerve can interfere with implant placement in the severely resorbed posterior mandible. However, complications in the interforaminal region may occur due to the presence of the mandibular incisive nerve. This scoping review aims to describe the mandibular incisive nerve anatomy related to the potential interference in implant therapy. A comprehensive literature search was conducted in the following databases: MEDLINE (via PubMed), Web of Science, and Scopus. This scoping review was structured according to the Joanna Briggs Institute method. Thirteen studies were included in the review. All of the studies were observational cohort anatomical studies, carried out mainly by CBCT and on cadavers. A total of 1,471 patients/cadavers were studied. The mandibular incisive nerve was present in 87% to 100% of cases, with an average length of 9.97 mm and an average diameter of 1.97 mm. The mandibular incisive nerve may be damaged during drilling and implant placement, especially when using implant lengths > 12 mm. Damage to the mandibular incisive nerve due to implant placement could be present, but it is necessary to conduct more studies focusing on assessing mandibular incisive nerve damage to understand the clinical relevance of this nerve and its associated morbidities, such as neurosensorial alterations. Due to the different anatomical characteristics of this nerve, CBCT analysis is recommended for implant therapy in the anterior mandible to prevent the described complications.

Topic: All-on-Four Concept Literature Review

In patients with total edentulism, dental implant treatment is a treatment model which has been accepted scientifically, and with long-term outcomes [1,2]. Dental implants with immediate function by making implant-supported fixed full-arch restorations are becoming the gold standard in dental implantology [3-5]. Normally in literature successful prostheses are made using [6-8] implants in the maxilla and 6 implants in the mandible and applying posterior cantilever extension where it is necessary, in these treatments, hygiene controls can be easily performed especially in full arch screw-retained fixed prostheses [7-9]. In some cases maxillary sinuses for maxilla restricts the implant placement in the posterior region. The posterior implant treatment is also difficult in patients with resorbed mandible with a mandibular nerve located at the top of the alveolar crest. The all-on-four implant concept has been developed to prevent these disadvantages presented by Malo for the first time in 2003 and the all-on-four concept that began to be used in atrophic full arch mandibular and in the maxilla in 2005. In this technique implants are positioned in the pre-maxillary region in the maxilla and in the inter-foraminal region in the mandible.Anterior implants are placed to the lateral incisor sites or canine/first premolar region, posterior implants are placed to the second premolar or first molar region [12-16].

Peri-Implant Bone Loss in Fixed Full-Arch Implant-Supported Mandibular Rehabilitation: A Retrospective Radiographic Analysis

Background: the aim of the study was to assess, through orthopantomograms (OPGs), the existence of peri-implant bone loss of distal implants in implant-supported full-arch mandibular restorations. A comparison between full-arch implant-supported rehabilitations performed in the inter-foraminal region and full-arch rehabilitations that include implant insertion distal to the mental foramen was conducted. Methods: a retrospective observational analysis of 17,950 OPGs from 2010 to 2020 was conducted. The presence of fixed implant-supported prostheses in a fully edentulous mandible was the inclusion criteria of the study. OPGs were divided according to the number of implants (four, six, and eight), position of the implants (mesial or distal to the mental foramen), and positioning patterns (models 1, 2, 3, 4, and 5). Results: a total of 51 OPGs were included in the study, 19 of which showed peri-implant bone loss. In particular, 16 belonged to the six-implant rehabilitation group and 3 to the eight-implant rehabilitation group; none of the four-implant-supported rehabilitations were affected by peri-implant bone loss. In all rehabilitations affected by peri-implant bone loss, the distal implant was the most involved, in particular the implant in positions 36 and 46. Conclusions: implants distal to the mental foramina are more susceptible than mesial implants to bone resorption in full-arch fixed implant-supported prostheses. This significant difference should be investigated further for the presence and synergy of biomechanical factors that could act predominantly in this area, such as mandibular flexure and occlusal loading.

Dental implant in anterior mandible according to mandibular lingual foramens and lingual mucosal vessels: using fusion volumetric images from computed tomography and magnetic resonance imaging

BackgroundPerforation of the lingual cortex while placing dental implants in the interforaminal region of the mandible can cause severe hemorrhage. The purpose of this study was to evaluate the features of mandibular lingual foraminals (MLFs) and locational relationship between them and lingual mucosal vessels (LMVs) by CT/MRI fusion volumetric images.Methods37 images within complete anterior mandibular region using both MSCT and three-dimensional volumetric interpolated breath-hold examination (3D-VIBE) MRI were taken from our imaging archives. After exclusion of 11 for lesions or artifacts, 26 CT/MRI fusion volumetric images were included to evaluate the frequency, diameter, and position of MLFs. The anterior mandibular region was divided into 4 equal segments under each teeth, and 40 regions were got from C5 to D5. Furthermore, the positional relationship between MLFs and LMVs was analyzed in this coordinate system.Results62 MLFs (73.81%) were located below the incisors, followed by premolars (21.43%) and canines (4.76%). Female bias, the mean diameter of the female was 0.08 mm while the male was 0.21 mm. The total number of LMVs was most distributed on lingual side of C1 and D1. According to Spearman’s correlation coefficient, the location of MLFs was related to LMVs. The MLFs in fourth segment of D1 were positively moderately correlated with LMVs in fourth segment of D4, while the MLFs in third segment of C1 showed a weak positive correlation with LMVs in third segment of D4.ConclusionsThe features and the correlation between MLFs and LMVs in CT/MRI fusion volumetric images may offer reference to dentists when only MLFs can been seen on routine preoperative CT examination of implants.Trial registrationRetrospectively registered. (D2018-072)

Comparative Evaluation of Survival Rates and Marginal Bone Levels of Nonsplinted Immediately Loaded Interforaminal Mandibular Implant-Retained Overdentures: A Randomized Controlled Clinical Trial with 5-Year Results.

Τo evaluate and compare the marginal bone loss (MBL), survival rates, and periodontal parameters of immediately loaded implants with either Dolder bar or Locator attachments placed in the interforaminal region of edentulous mandibles. A total of included 19 patients with edentulous mandibles each received two implants in the interforaminal area of the symphysis. Randomly allocated Dolder bar or Locator attachments were then attached immediately, and both clips and a framework were fastened to the denture by the dental laboratory within 24 hours. A total of 28 subjects with 56 implants were treated in accordance with the immediate-loading study protocol. Of these, 9 patients were lost to follow-up; 1 patient reported a serious illness and 8 patients moved and couldn't be reached. The 19 subjects not lost to follow-up (11 women and 8 men; average age: 68 years) were included. Every patient received either two Locator abutments and were assigned to group A (7 patients; 36.8%) or two multiunit abutments and were assigned to group B (12 patients; 63.2%). No implant failure was detected for either group, and therefore the survival rate for both groups was 100% after 5 years. After 5 years without any symptoms, 2 implants from group A and 7 implants from group B showed > 2 mm of MBL, which makes the group A success rate 85.7% and the group B success rate 70.8%. Modified sulcular bleeding index (mSBI) did not differ significantly at any of the measurement intervals. However, the modified plaque index (mPI) of group B was significantly higher than group A at the 60-month follow-up. It can be concluded that either splinting or not splinting the immediately loaded interforaminal implants to retain mandibular overdentures (OVDs) does not affect marginal bone levels after 5 years and immediate loading of nonsplinted implants with Locator attachments can be safely preferred to retain mandibular OVDs.

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.

Primary and Secondary Stability of Short (4 mm) Versus Standard (≥ 10 mm) Implants Placed in the Same Mandible: A Prospective Clinical Study.

Purpose: To compare the stability of short vs standard (ie, regular-length) implants in the edentulous mandible. Materials and Methods: In this prospective clinical study, 20 patients with edentulous mandibles received four implants each-two short implants (4 mm) in the region of the first molar and two standard implants (≥ 10 mm) in the interforaminal region. Implant stability was assessed using resonance frequency analysis immediately after implant placement and at the day of the abutment connection after 3 months of healing in order to provide an implant stability quotient (ISQ). Results: Implant stability in the two implant groups at placement (ISQ: short 66.2; standard 68.2) and at abutment connection (ISQ: short 74.9; standard 75.7) did not differ substantially or statistically significantly (both P > .05). Findings did not change after statistically controlling for potential confounders such as bone quality and bone crest width. At abutment connection, 95% of the short and 97.5% of the standard implants demonstrated sufficient stability for conventional loading (P > .05). Conclusions: Short dental implants demonstrate similar primary and secondary stability compared to standard implants and seem to be a promising treatment option for rehabilitation of patients with edentulous mandibles.

Marginal Bone Level Measurements of Unsplinted Implants Used for Mandibular Overdentures: A Six-Month Randomized Prospective Clinical Study Comparing Early and Delayed Loading Protocols.

Background and purpose Implant-supported mandibular overdentures are a good alternative for patients having poor retention of mandibular conventional dentures. The aim of this prospective study was to evaluate and compare the results between early loading and delayed loading of mandibular overdentures on two unsplinted implants. Materials and methods A total of 14 completely edentulous male patients in the age group of 50-60 years were selected for the study. Two 3.5×13 mm implants were placed in the mandibular interforaminal region. The patients were divided into two groups: (i) the test group in which the overdenture was connected after one week of surgery, and (ii) the control group, in which the overdenture was connected three months after surgery. Marginal bone levels were evaluated at baseline (during loading), three months, and six months post loading. Unpaired 't' test was used for the comparison of intergroup measurements. Results No implants were lost. Marginal bone resorptions showed no statistically significant differences between the two groups over six months period after loading. Conclusion The results of this prospective clinical study suggested that there was no significant difference in the clinical and radiographic state of patients treated with implant-supported mandibular overdentures loaded either one week or three months after implant surgery.

SAFE MARGIN FROM MENTAL FORAMEN FOR SURGICAL PROCEDURES IN INTER-FORAMINAL REGION IN EAST-INDIAN POPULATION: A CBCT ANALYSIS

Mental foramen is an important and easily identiable anatomical landmark for any surgical procedure in the inter-foraminal region. If a safe margin from the mental foramen is not maintained, it leads to inadvertent damage to the mental nerve leading to neuro-sensory decit. Aims and objective- The length of anterior loop of mental foramen varies with genders, different races and population. This study aims to assess the length of anterior loop of mental foramen and thus the safe margin from mental foramen in East-Indian population. Material and method- 100 CBCT images (of East-Indian population) were collected from Institutuional archive. It consisted of 200 sites of mental foramen. Length of anterior loop of mental foramen was measured. In the present study, the safe margin from mental foramen was calculated as 2 mm excess of the length of the anterior loop. The mean length of anterior loop of mental foramen was found to be 3.06 ± 1.62 Result- mm and the mean safe margin from mental foramen was 5.06 ± 1.62 mm. No statistically signicant difference was found among the genders, sides and different age groups. We Conclusionrecommend a safe margin of 5mm from mental foramen. Individual pre-operative radiographic evaluation of mental foramen and its loop is of utmost importance

Mandibular İnterforaminal Bölgede İmplant Cerrahisinde Karşılaşılabilecek Vasküler Komplikasyonlar ve Yönetimi

Mandibular interforaminal bölge, birçok ağız ,diş ve çene cerrahisi protokolünde özellikle de dental implant uygulamalarında tercih edilen bir alandır. Son yıllardaki vaka raporları, mandibular interforaminal bölgede birçok komplikasyonla karşılaşılabileceğini göstermektedir. Bunlardan en tehlikeli ve yaşamı tehdit edeni de üst solunum yolu obstrüksüyonuna kadar varabilen lingual arter yaralanmalarıdır. Tecrübeye bağlı olmaksızın karşılaşılabilecek bu komplikasyondan kaçınmak ancak mandibular interforaminal bölgenin vasküler anatomisine hakim olmak, işlem öncesi gerekli radyografik tetkik ve incelemeleri yapmış olmaktan geçmektedir. Hastayla ilgili yetersiz radyografik tetkik bulunması ya da anatomik varyasyon varlığı gibi durumlarda bu şekilde bir kanama komplikasyonuyla karşı karşıya kalındığındaysa, hekimin süreci ve komplikasyonu yönetebilecek bilgi ve donanımda olması gereklidir. Bu çalışmada mandibular interforaminal bölgesinin anatomik vasküler anatomisi, lingual foramenler ve bulunma sıklıklarıyla birlikte komplikasyondan kaçınma ve başa çıkma yöntemleriyle ilgili literatür özetlenmiştir. Böylece diş hekimlerinin bu ciddi komplikasyonla ilgili bilgilerini tazelemek amaçlanmaktadır.

PREVALENCE, DIAMETER AND FURRING OF MANDIBULAR INCISIVE CANAL IN NORTH INDIAN SUBPOPULATION: A CBCT STUDY

Objective: The Mandibular Incisive Canal (MIC) carries mandibular neurovascular bundle and it is necessary to determine the presence of MIC & its relation to adjacent anatomical landmarks to avoid any potential damage to neurovascular bundle during various surgical procedures. So, this study was planned to determine the prevalence, canal diameter and its relation with adjacent anatomic structures using CBCT and to find their associations with age, gender and laterality. Methods: CBCT scans of 61 patients (33 M, 28 F) were evaluated in sagittal sections. Results: The overall prevalence of MIC on the right side was found to be 65.6% while it was 73.8% on the left side. The MIC was more prevalent in females as compared to males between the 30-50 years of age. The mean diameter on the right and left side was found to be 0.85 ± 0.25 mm & 0.93 ± 0.27 mm respectively. The mean distance of MIC from buccal cortex was (3.5 ± 1.3 & 3.6 ± 1.8 mm), lingual cortex (4.8 ± 1.6 & 4.8± 2.0 mm) & inferior border of the mandible (10.1 ± 3.7 &10.4 ± 3.3 mm) on right and left side respectively. Conclusions: The preoperative assessment of CBCT is advocated especially in middle age, females and left side for MIC evaluation &the findings of this study will help in identifying safe area during surgical procedures in inter-foraminal region. Periapical surgery, implants, genioplasty etc. can be planned in a better manner by avoiding potential danger areas.

ROLE OF CBCT IN IMPLANT PLACEMENT IN MANDIBULAR PREMOLAR REGION

Implant placement has now become the lifeline of dentistry, but the most of the aspect of its treatment begins with the diagnosis of patients condition.Rehabilitating patients with dental implants require thorough evaluation of the implant site.All the vital structures need to be evaluated and a safe distance should be maintained while planning for implant like the nasal floor, maxillary sinus in maxillary region and mental foramen, inferior alveolar nerve and sublingual concavities in the mandible. The mandibular anterior inter-foraminal region was previously considered to be a safe region for surgical procedures of the mandible but now it has been realized that presence of anterior loop of inferior alveolar nerve make it an area that should be thoroughly evaluated. The selection of a suitable imaging modality along with the judgment of the expert clinician about the clinical situation aids in the treatment planning. Previously clinicians were relying on 2-dimensional imaging techniques, which have now been replaced by CBCT, the most widely used tool for treatment planning of implant placement.

Morphology and morphometric analysis of mental foramen in south Indian population – A CBCT study

It is essential to define the exact location of the mental foramen to avoid potential injury to the neurovascular bundle during surgical procedures in the mandibular interforaminal region. This radiographic study was aimed to evaluate the morphology and morphometric dimensions of mental foramen (MF) among Indian population. This study also investigated the dimorphic variations of mental foramen with respect to gender and laterality. The images of 80 subjects( 160 mandibular sites) with the age range of 20 to 60 years who had undergone cone beam computed tomographic (CBCT) were retrieved from the archives and examined for morphology and morphometry of mental foramen. Oval shaped mental foramen was one and a half times greater than round shape, which was predominant in females. Position 4 was the most common location on right and left side respectively. Type I and type III were the most common radiographic appearance of mental foramen on right and left side respectively. The mean mesiodistal, superoinferior and buccolingual dimensions of MF were 2.49 ± 0.86 mm, 2.83 ± 0.73 mm and 2.44 ± 0.72 mm respectively. The mean dimensions of the mental foramen were significantly higher among the males when compared to females. The mental foramen was positioned at an average of 11.13 ± 3.40 mm from the alveolar crest (MF-C) on the right side and was positioned at 10.79 ± 3.21 mm on the left side. The distance of the mental foramen from the alveolar crest was significantly higher among the Group I when compared to Group IV. The morphology of the mental foramen did not show any variations among the gender and age in the Indian population. The morphometric values of the mental foramen showed variability of 1-2 mm among different subjects of our population.

Detection Rate and Variability in Measurement of Mandibular Incisive Canal on Cone-Beam Computed Tomography: A Study of 220 Dentate Hemi-Mandibles from Italy

The mandibular incisive canal (MIC) is a small bony channel located in the interforaminal region; it represents the anterior continuation of the mandibular canal. Cone-beam computed tomography (CBCT) is the most commonly utilized radiological technique for assessing the MIC. The main purpose of this study was to evaluate the detectability and variability in measurements of the MIC on CBCT. A total of 220 dentate hemi-mandibles were retrospectively selected for this study. For each hemi-mandible, the detectability, diameter, and distance of the MIC from anatomical landmarks (cortical plates and tooth apices) were evaluated in consensus by two observers. The analysis was performed at four different levels (first premolar, canine, lateral incisor, and central incisor) and was repeated after one month. The variability of MIC measurements was expressed as the coefficient of repeatability (CR), obtained from the Bland–Altman analysis. The MIC detection rate reduced from the first premolar to the central incisor (from 82.3% to 0.5%). The CR of MIC measurements (diameter and distances from anatomical landmarks) was ≤0.74 mm. Although the MIC is difficult to detect in a non-negligible percentage of cases, the limited variability in measurements confirms that CBCT is an effective technique for the assessment of the MIC.

Determination of Morphogeometric Patterns in Individuals with Total Mandibular Edentulism in the Interforaminal Region from Cone Beam Computed Tomography (CBCT) Scans: A Pilot Study

The aim of this study was to determine the morphogeometric patterns of the interforaminal region from cone beam computed tomography (CBCT) scans of individuals with total mandibular edentulism. CBCT images were obtained from 40 patients with total edentulism who are older (12 men and 28 women; average age of 69.5 ± 9.4 years) and who wore a non-implant-supported, lower, removable, total prosthesis. We conducted a two-dimensional (2D) morphogeometric analysis of the Digital Imaging and Communication in Medicine (DICOM) files from the CBCT scans, and five equidistant cross sections were planned. For the three-dimensional (3D) morphogeometric analysis, standard triangular language (STL) files were obtained after segmentation of the interforaminal mandibular region, and four anatomical landmarks and their respective curves were digitized. The patterns among the shapes were determined using principal component analysis (PCA) on MorphoJ software (version 1.07a). The results of the 2D morphogeometric analyses for PCA of the interforaminal mandibular paramedian region were PC1 or elongated drop shape, 54.78%; PC2 or wineskin shape, 17.65%; PC3 or pear shape, 11.77%; and PC4 or eggplant shape, 5.71%, and those for PCA of the symphyseal region were PC1 or elongated drop shape, 62.13%; PC2 or ovoid shape, 11.64%; PC3 or triangular shape, 9.71%; and PC4 or tuber shape, 4.96%. The results of the 3D morphogeometric analyses for the interforaminal hemimandibular region were PC1, 59.83%; PC2, 10.39%; PC3, 7.67%; and PC4, 5.09%. This study provides relevant information for future clinical guidelines on prosthetics and implants, in addition to proposing the use of new technologies that support diagnosis and treatment in patients with edentulism.

Assessment of Implant-Related Anatomical Landmarks in the Mandibular Interforaminal Region in an Iranian Population Using Cone-Beam Computed Tomography.

Background:This study was aimed to assess the implant-related anatomical landmarks in the mandibular interforaminal region in an Iranian population using cone-beam computed tomography (CBCT).Methods:In this retrospective cross-sectional study, 378 CBCT images of the mandible were evaluated for the presence of the incisive canal, anterior loop of the inferior alveolar nerve (IAN), mandibular canal, mental foramen, and incisive canal. The effect of age and gender of patients on the abovementioned variables was also evaluated. Data were analyzed using independent t-test, analysis of variance, and Chi-square test.Results:The anterior loop and the incisive canal were present in 36.24% and 97.62% of the cases, respectively. The mean length of the anterior loop and the incisive canal was 2.70 ± 1.20 mm and 12 ± 3.29 mm in the right, and 2.86 ± 1.24 mm and 12.21 ± 3.38 mm in the left side, respectively. The mean diameter of the mental foramen and incisive canal was 4.25 ± 1.08 mm and 1.89 ± 0.46 mm in the right, and 4.21 ± 1.02 mm and 1.94 ± 0.45 mm in the left side, respectively. The descending path was the most common path of the incisive canal. The distance from the incisive canal to the buccal plate and inferior border of the mandible was significantly shorter in females (P < 0.001).Conclusion:Considering the high variability and clinical significance of the incisive canal and anterior loop of the IAN, and their high prevalence, it is recommended to assess the presence/absence of these structures in the interforaminal region of the mandible on CBCT scans before surgical procedures in this region.

Distraction Osteogenesis of Severely Resorbed Mandible

Edentulous patients require an adequate rehabilitation so that the alveolar ridge in the interforaminal region be restored for subsequent implant-supported overdentures. The ultimate goal of distraction is to reconstruct the alveolar ridge to a suitable height and width compatible with Atwood class 2 in an appropriate direction allowing the sagittal interalveolar relation to be normally restored. Methods. A 65-year-old man presented with a grade 4 Mandibular atrophy as per Atwood classification which resulted in unsatisfactory treatment with full dentures. Endo-Distractor Krenkel® device was used for anterior mandibular vertical distraction osteogenesis. Four mandibular implants (ITI Straumann, Basel, Switzerland) measuring diameter Ø = 4.1 mm and length L = 16 mm were inserted after the required retention period. Standardized prosthetic treatment was completed with titanium bar retained over dentures. Results. A distraction of 11 mm was achieved within 18 days followed by a retention period of 4 months. No signs of infection nor distractor anchorage loosening were detected, and minimal lingual tilting has occurred. Conclusion. Distraction is possible on severely atrophic mandibles. The quality of bone reconstruction is satisfactory for both functional and esthetic results.