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Lack of knowledge concerning the inferior alveolar canal anatomical variations had proven to increase the incidence of surgical complications, so the study aimed to assess the configuration and prevalence of bifid and trifid mandibular canals using cone beam CT in Egyptian subpopulation. Cone beam CT scans of 278 patients (530 hemi-mandibles) were included in the study, in which bifid and trifid mandibular canals or any other branching patterns were recorded and evaluated. Bifid canals were categorized following Naitoh classification, and the diameter of the main mandibular and accessory canals was measured. Bifid canals were detected in 181 canals (34%) while trifid canals in 46 canals (8.7%). Upon classifying the bifid canals, 78 canals showed forward type, 40 retromolar type, 33 dental type, and 7 canals showed buccolingual type. Two special bifid canals subtypes were reported in 23 canals and nine distinct patterns of trifid canals were reported in our study. In addition, unusual patterns of canal branching were reported in 5 cases. The mean diameter of the accessory canals was 1.18 ± .54 mm and the main canal was 3.98 ± 1.31 mm. This study reported a high prevalence (54%) of canal branching, which reinforces the importance of cone beam CT in pre-surgical planning.

Inferior alveolar nerve (IAN) damage following implant placement is a severe complication that can compromise a patient's quality of life. Previous studies have suggested that a safety zone of 2 mm, if maintained, might avoid this problem. This retrospective study evaluates implants placed in closer proximity to the IAN without resulting in any postoperative neurologic complications and suggests a new concept of safety distance. A total of 60 consecutive patients receiving 101 mandibular implants < 2 mm from the IAN were included in this study. All enrolled patients had a CBCT scan done for radiologic assessment before implant placement and following final restoration. Measurements were obtained through cross-sectional views using Simplant software. In patients without neurologic disturbances, a mean distance of +0.75 mm was seen from the closest portion of the implant to the nerve bundle. In cases where a direct transection and/or compression of the nerve was not observed, the patients did not experience neurosensory disturbances.

Background: Mandibular third molar’s roots have close proximity to the inferior alveolar canal (IAC) and nerve. Inferior alveolar nerve injuries have been observed to occur more frequently when there is radiographic evidence of close contact of third molar roots to the IAC. Orthopan­tomogram is one of the commonly used diagnostic tools for evaluating the relationship between these two structures. There is lack of data regarding prevalence of these radiographic signs in Nepalese population. It was required to assess the reliability on the radiographic signs of relation­ship between the IAC and the third molar roots, to establish IAC as risk indicators for IAC exposure during extraction. Methods: A single centre cross-sectional descriptive study was designed where demographic data and radiographic signs of third molar roots proximity to IAC were obtained from imaging software records and descriptive analysis was performed with SPSS version 20. Results: One or more radiographic signs were observed in 49.6% of mandibular third molars. In­terruption of white line followed by narrowing of canal and darkening of roots was observed in decreasing order of frequency and no statistically significant association between sex, age and side of impacted third molar with presence of radiographic signs. Conclusions: Presence of one or more radiographic signs of proximity of mandibular third molar roots with IAC in nearly half of the cases. Clinicians should be aware of risk of nerve injury on pres­ence of these signs. Further investigation with cone beam computed tomography to rule out any nerve injury risk should be adopted into practice.

Objective: The aim is to evaluate the location and proximity of second and third molars roots to the inferior alveolar canal (IAC) and demographic factors associated with these proximities. Materials and Methods: Cone beam computed tomography scans were evaluated for 292 roots of 146 teeth from 40 patients. A radiologist read, measured, and evaluated the vertical and horizontal positions of the roots of the second and third molars in relation to the IAC. Results: No significant differences were found between the third molar roots and neighboring second molar roots in the closeness to the IAC. The most common horizontal relation was “roots above IAC” (54%) followed by “roots lingual to IAC” (41.78%), “roots buccal to IAC” (3.42%), and “IAC between the roots” (0.68%). No significant differences in second and third molar roots and their contrasting teeth in the proximity to IAC. The older age group had significantly higher vertical measurements between third molar roots and IAC. There were significantly larger vertical measurements in the right third molar roots to IAC in males than females. Conclusions: These anatomical relationships are important clinical knowledge to avoid potential surgical injury to the inferior alveolar nerve.

The aim of this study was to introduce a method to evaluate the risk of inferior alveolar nerve (IAN) injury following the extraction of impacted lower third molars. Two hundred impacted lower third molars adjacent to the IAN were evaluated. These were divided into four classification groups according to preoperative cone beam computed tomography (CBCT) findings: AR, apical region; LT, lateral region of the tapered root; LE, lateral region of the enlarged root; AE, adjacent to the enlarged root. All teeth were dislocated along the long axis or arc of the root by tooth sectioning technique and extracted by a single surgeon. The primary outcome variable was postoperative neurosensory impairment of the IAN. The χ2 test was used to evaluate differences in postoperative IAN injury between the classifications. Logistic regression analysis was used to evaluate the risk factors for postoperative IAN injury. The overall incidence of postoperative IAN injury was 7%. Specifically, most injuries involved classification AE (AE 36%, LE 8.6%, LT 3.6%, AR 0%), and the difference was statistically significant (P< 0.05). Logistic regression showed that classification AE was the only risk factor for postoperative IAN injury (P< 0.001). According to preoperative CBCT, the risk of postoperative IAN injury is higher when the IAN is adjacent to the enlarged part of the root.

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.

Context: Relation of inferior alveolar nerve to the impacted mandibular third molars (IMTMs). Aims: The aim of this study was to assess the reliability of seven specific radiographic signs of mandibular third molar root that are observed on orthopantomography (OPG) and to predict the proximity and the absence of corticalization between the mandibular canal and IMTM root on cone-beam computed tomography (CBCT) images. Settings and Design: The present study was conducted in the Department of Oral and Maxillofacial Surgery, Raja Rajeswari Dental College and Hospital. Subjects and Methods: Data set of 30 panoramic images was retrieved between the year of 2015 and 2016 indicated for extraction of lower third molars. The sample consisted of 30 individuals, who underwent preoperative radiographic evaluation before the extraction of impacted mandibular third molars (IMTM). Patients aged above 18 years with any of the seven specific signs observed on the panoramic radiograph which includes darkening, deflection, narrowing of roots, bifid root apex, diversion, narrowing of canal and interruption in the white line of the canal were included in the study. If any of the above mentioned seven specific sign were present, the patient was subjected to CBCT. On the CBCT images, the canal was traced in three planes. The acquired images were assessed for the presence or absence of corticalization. Statistical Analysis Used: Descriptive and inferential statistical analyses were used. Proportions were compared using the Chi-square test and Student's t-test. Results: Among the 4 subjects, diagnosed with an absence of corticalization, patients with isolated darkening of root P = 0.001 and patients with isolated interruption in white line P = 0.69. Patients with darkening of root in association with interruption in white lines on OPG showed the absence of corticalization on CBCT findings P = 0.001, respectively. Conclusions: This study showed the poor reliability of radiographic signs seen on OPG on predicting the proximity of third mandibular root with mandibular canal related to CBCT finding. Four were diagnosed with the absence of corticalization in CBCT findings.

Traditional surgical approaches to the inferior alveolar nerve (IAN) pose a technical challenge and risk iatrogenic damage to healthy, uninvolved nerve tissue. The use of computer-assisted virtual surgical planning and fabrication of surgical guides has shown efficacy in various craniomaxillofacial surgical procedures, and may provide greater precision in accessing the inferior alveolar canal and allow for a more conservative approach. The addition of a depth control feature to a tooth-borne and bone-borne surgical guide, with the use of a standard contra-angle handpiece, provides safe and efficient access for IAN repair. This report describes this novel technique involving a guided transoral approach to the IAN for excision of a neurofibroma of the inferior alveolar nerve, with immediate peripheral nerve allograft IAN reconstruction.

Inferior alveolar nerve (IAN) entrapment in third molar (M3) roots bears a significant risk for nerve injury. The aim of this study was to identify specific panoramic radiographic (PR) signs that can reliably identify IAN entrapment (IANE) root conformations. In a retrospective case-control study, 10 IANE and 218 non-IANE third molar risk cases were examined by PR and CBCT. The collected data included “classic” specific high-risk panoramic signs, number of M3 roots, extent of inferior alveolar canal (IAC)−root tip overlap, rotated position of M3 and impaction pattern. After bivariate analysis, sensitivity, specificity, positive and negative predictive values, positive likelihood ratios (LR+) and accuracy (area under the curve [AUC]) were calculated for the most significant predictive variables. Interruption of both cortical lines (LR+: 43.6; AUC: 96.0%) and upward diversion of the IAC (LR+: 36.3; AUC: 96.5%) were the most accurate single signs indicating IANE. Upward diversion combined with root darkening and interruption of the IAC (AUC: 97.4%) and the combination of darkening with interruption and with a rotated M3 (LR+:130.8; AUC: 97.8%) were the most accurate combinations predicting IANE. IANE may be correctly filtered with PR when focusing on the signs of upward diversion, darkening, interruption and rotated M3 position, especially in cases involving their multiple (≥3) presence. CBCT evaluation is highly recommended in these cases before partial and total tooth removals.

Introduction: Although the inferior alveolar nerve had been described as a single entity that travels through the mandibular canal and leaves it through the mental foramen directly giving rise to mental nerve, presence of mental loop was reported. Improper identification of mental loop led to increasing the incidence of nerve injury during surgical procedures especially implant placement. Objective of the study: The purpose of this study was to assess mental loop and its length among a sample of Egyptians, using cone beam computed tomography (CBCT). Materials and Methods: Two hundred and sixty-seven CBCTs were collected in which one hundred were males and one hundred and sixty-seven were females, then evaluated for the presence of the mental loop. The length of the loop was measured on reconstructed panoramic views of CBCT using on demand software. Results: Mental loop was present in one hundred and nine patients (40% of the patients), 63 females and 46 males. The minimum length observed was 2.27 mm. while the maximum length was 7.18mm and the mean length was 4.36±.96mm. There was no significant difference between males and females. Conclusions: High prevalence of mental loop was detected in Egyptians. Based on this finding proper identification of mental loop by the method explained in this study prior to surgical planning is essential. Keywords: Anatomical variant, CBCT, inferior alveolar canal, mental nerve loop

Background and Objectives. Surgical extraction of mandibular third molars (3rd M) may cause inferior alveolar nerve injury (IANI), whereas in coronectomy the crowns of 3rd M are removed, keeping the roots intact to avoid IANI. This study aims to review the literature which evaluated coronectomy effectiveness as an alternative for surgical extraction of 3rd M that have a high risk of trauma to the inferior alveolar canal. A computerized literature search was conducted on the databases PubMed, SCOPUS, and ScienceDirect to gather information regarding the coronectomy procedure from inception till June 5, 2020. A total of 97 articles were identified, and seven studies were finally included for conducting qualitative analysis: 3 randomized clinical trials and 4 clinical controlled trials. Cochrane Collaboration’s tool was used for assessing risk of bias. Coronectomy procedures were performed on 15–171 teeth. In the control group, extraction procedures were done on 15–178 teeth. Results. No study reported permanent inferior alveolar nerve injury (p-IANI) regarding coronectomy; however, transient inferior alveolar nerve injury (t-IANI) was reported in 0–2.20% of successful coronectomy and 0–8% of failed coronectomy. Postextraction t-IANI ranged from 0% to 16.66% while p-IANI from 0% to 3.63%. In 5 studies, root migration occurred in 2% to 85.3% of cases and the distance rate was 2.33–3.43 mm at 6 months postoperatively; then the migration gradually decreased and stopped at 12 months. Conclusion. This systematic review revealed that coronectomy is an efficient alternative for the management of impacted 3rd M with a high risk of IANI. Patients who got antibiotics postcoronectomy procedures had lower infection rates than those who did not receive antibiotic therapy. We recommend further research on coronectomy with longer follow-up periods to assess the retained roots’ long-term outcomes and to assess the effect of antibiotics administration on postcoronectomy infection rate. This systematic review is registered under number CRD42020198394.

Introduction The mandibular canal, as it was formerly named in Terminologia Anatomica (TA), has also been called the inferior alveolar (nerve) canal in many scientific publications. This study was conducted to investigate how these terms have been understood in different regions and different areas of expertise and to discuss the appropriate future application of the term "mandibular canal." Methods A literature search was conducted using PubMed, and articles using different terms for this structure were classified into two groups, inferior alveolar canal/inferior alveolar nerve canal (IAC/IANC) and the mandibular canal (MC). The 50 most recent articles in each group were included. Publication year, journal title, country of the first author, and affiliation of all authors were recorded in both groups for all 100 articles. Results There was a significant difference between the IAC/IANC and MC groups in the numbers of anatomy journals, other journals, and anatomy affiliations. Turkey published most frequently with a total of 15 articles, followed by Iran with 10 articles, and China/India/United States with seven each. When the six countries of the first author that had three or more publications in each group were compared, only Turkey appeared in both groups; otherwise, different countries were in the two groups. Conclusions Based on the results of this analysis, and considering that the tentative new term "inferior alveolar foramen" is used in the latest TA, we suggest that the mandibular canal should be renamed the "inferior alveolar canal."

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.

Placement of dental implants in the posterior mandibular alveolar ridges may become a challenging procedure because of limited bone height between the crest of the ridge and the inferior alveolar canal. The aim of this study was to introduce an innovative, less invasive, highly accurate, and easy surgical technique of inferior alveolar nerve lateralization in the posterior deficient mandible using a special customized 3-dimensional–printed surgical guide to enhance the bone height for implant placement. This case series study included 7 patients with unilateral edentulous mandibular alveolar ridges. Customized surgical guides were manufactured using fused deposition modeling technology to accurately place a rectangular window to uncover the canal and also for immediate placement of dental implants in all cases. The results of this limited study provided information on an innovative technique that decreased intraoperative time and demonstrated decreased risks for (1) inferior alveolar nerve injury and (2) postoperative nerve dysfunction.

الملخص: أهداف البحث: هدفت هذه الدراسة إلى التحقق من دقة علامات الخطورة في التصوير الاشعاعي البانورامي من خلال الكشف عن وجود أو عدم وجود التكون القشري بين ضرس الرحى السفلي الثالث المدفون والقناة السنخية السفلية في الأشعة المقطعية المخروطية. طرق البحث: دَرست هذه الدراسة الاسترجاعية ٢١٠ ضرسا فكيا سفليا ثالثا منغرسا من ١٣٥ مريضا (بأعمار من ١٧ -٥١ سنة) والذين أظهروا واحدا أو أكثر من علامات الخطر البانورامية السبع المقترحة للتعرض العصبي السنخي السفلي. أُحيل هؤلاء المرضى للفحص بالأشعة المقطعية المخروطية. واستُخدمت الصور ثلاثية الأبعاد لتقييم موقع القناة بالنسبة للضرس الثالث، وقرب القناة من الضرس الثالث وزاوية ميول الضرس الثالث. وقورنت نتائج الأشعة البانورامية والأشعة المقطعية المخروطية. النتائج: كانت نتائج الأشعة البانورامية عندما بينت انقطاع جدار القناة السنخية السفلية، سواء كان ذلك مقترنا أو غير مقترن بإحدى هذه العلامات؛ سواد جذور الضروس الثالثة، وضيق القناة، وانحراف القناة، وبخاصة سواد الجذور، وضيق القناة كان مرتبطا ارتباطا ذا قيمة إحصائية بالاتصال المباشر بين قناة الفك السفلي والأضراس الثالثة المنغرسة في الأشعة المقطعية المخروطية. الاستنتاجات: يُوصى بعمل الأشعة المقطعية المخروطية قبل العملية في الحالات التي تبين سواد الجذور، أو ضيق القناة، أو التي تبين الانقطاع والضيق معا، أو انحراف أو سواد الجذور معا في الأشعة البانورامية. وقد قيمت هذه الدراسة علاقة الخطورة بين العصب السنخي السفلي والأضراس الثالثة في الفك السفلي المنغرسة وآلية الحد من حدوث إصابة ما بعد الجراحة في العصب السنخي السفلي. Abstract: Objectives: This study aimed to validate the accuracy of panoramic radiographic risk signs through detection of presence or absence of corticalization between an impacted mandibular third molar and the inferior alveolar canal on cone beam computed tomography (CBCT). Methods: This retrospective study analyzed 210 impacted mandibular third molars from 135 patients (aged 17–51 years) who showed one or more of the seven previously established panoramic radiographic risk signs of inferior alveolar nerve exposure. These patients were referred for CBCT examination. Three-dimensional images were used to assess the canal position relative to the third molar, the proximity between the canal and third molar, and third molar angulation. The correlation of panoramic findings and CBCT was evaluated using a Chi-square test. Results: Panoramic findings of interruption of inferior alveolar canal wall, isolated or combined with one of these signs (darkening of third molar roots, narrowing of canal, and diversion of canal); darkening of the roots; and narrowing of canal were significantly correlated with direct contact between the inferior alveolar canal and impacted third molars on CBCT (P

Introduction The present study was aimed to identify the radiographic signs between impacted third molar root and inferior alveolar canal (IAC) on cone-beam CT (CBCT) images as risk factors and prognostic predictors associated with inferior alveolar nerve (IAN) damage following tooth removal. Material and methods A retrospective clinical study was performed involving 136 patients with 257 impacted lower third molars from January 2013 to December 2014. The neurosensory function of the lower lip and chin was subjectively evaluated and assessed by neurosensory tests before and after surgery. The preoperative CBCT data were retrieved and analyzed to identify the radiographic signs associated with postoperative IAN injury. Results The overall incidence of IAN injury in our patient cohort was 13.2%. Multiple radiographic features on coronal CBCT images including contact between IAC and root, IAC position relative to root, IAC shape and cortication status were found to be significantly associated with IAN damage (p < 0.05, χ2 test). Furthermore, buccolingual position, teardrop/dumbbell shape and cortication status of IAC were identified as independent prognostic predictors for IAN damage. Conclusions Our findings indicate that radiographic signs including direct contact between IAC and root, buccal/lingual IAC position relative to root, teardrop/dumbbell shape and cortication absence of the IAC on presurgical CBCT images are associated with high risk of IAN injury and postoperative neurosensory disturbance.

Background and objective: Extraction of an impacted mandibular third lower molar tooth is one of the common surgical procedures that may lead to the damage of inferior alveolar nerve due to roots proximity to the mandibular canal. This study aimed to know the relative relationship and proximity of the mandibular third molar roots to the inferior alveolar canal in relation to gender, age, depth of impaction, relation with ramus, and type of angulation of the impacted tooth in Kurdistan population. Methods: A sample of 366 digital panoramic radiographs of patients with impacted mandibular third molar was studied. Panoramic radiographic signs images were evaluated for the presence of root contact with the superior border of the mandibular canal, darkening of the roots apex, deflected roots, narrow root, superimposition of the canal, interruption of the white line, diversion of the inferior alveolar canal, and narrowing of the inferior alveolar canal. The depths of impaction, relation with ramus, and type of angulation were also studied. Results: Significant relation of the proximity of the mandibular third molar roots to the inferior alveolar canal with the gender (P = 0.001) and age (P

The extraction of mandibular third molars can lead to injury to the inferior alveolar nerve. Hence, it is important to assess the proximity of the root to the inferior alveolar canal before extraction. The classification system of Pell and Gregory and the Winter classification are commonly used to evaluate the positional relationship of the third molar based on radiographs. This retrospective study involving 105 mandibular third molars was performed to assess whether these systems reflect the proximity of the root to the canal (based on computed tomography images), and to identify risk factors for nerve injury. Regarding the prediction of computed tomography-verified canal invasion, the sensitivity, specificity, and positive and negative predictive values were high for each Pell and Gregory category when there was radiographic evidence. The mean distance of invasion was significantly greater in class III than in class I. However, there were no significant differences between the Winter inclination categories. The mean distance differed significantly between a horizontal inclination angle to the buccal side of >5° and an angle of ≤5°. Thus, a horizontal inclination angle >5° represents a novel risk factor for nerve injury.

A retrospective cohort study was performed to assess the clinical usefulness of combination assessment using computed tomography (CT) images in patients undergoing third molar extraction. This study included 85 patients (124 extraction sites). The relationship between cortication status, buccolingual position, and shape of the inferior alveolar canal (IAC) on CT images and the incidence of inferior alveolar nerve (IAN) injury after third molar extraction was evaluated. IAN injury was observed at eight of the 124 sites (6.5%), and in five of 19 sites (26.3%) in which cortication was absent+the IAC had a lingual position+the IAC had a dumbbell shape. Significant relationships were found between IAN injury and the three IAC factors (cortication status, IAC position, and IAC shape; P=0.0001). In patients with the three IAC factors, logistic regression analysis indicated a strong association between these factors and IAN injury (P=0.007). An absence of cortication, a lingually positioned IAC, and a dumbbell-shaped IAC are considered to indicate a high risk of IAN injury according to the logistic regression analysis (P=0.007). These results suggest that a combined assessment of these three IAC factors could be useful for the improved prediction of IAN injury.

The aim of this in vitro study was to investigate temperature increases in the inferior alveolar canal (IAC), when different bone preparation methods approximate and penetrate the IAC.In pig mandible, buccal bone removals were performed until the neurovascular bundle became visible. Temperatures were registered with thermocouple probes and with infrared thermometer. Preparations were performed with diamond drills (DD), tungsten carbide drills (TCD), piezoelectric diamond sphere (PT_D) and saw (PT_S) tips, and a combined preparation method was also performed whereby the superficial three-fourths of the bone was removed with TCD and the deepest one-fourth of the bone with PT_D (TCD + PT_D_7 °C) or PT_S (TCD + PT_S_7 °C), using cooled irrigation (7 °C).Preparations using room temperature irrigation caused significantly less heat on the bone surface than in the IAC. Piezosurgery in the IAC produced significantly higher temperatures (13 °C) than the drills (4 °C). Heat productions of the piezoelectric tips were reduced significantly by applying the combined bone removal methods. The speed of PT_S and TCD + PT_S_7 °C were comparable to the speed of TCD, whereas TCD + PT_D_7 °C was found to be significantly slower.The speed of piezosurgery is comparable to that of the drills; however, it produces the highest, potentially nerve-harming temperatures. To eliminate the heat consequences during piezosurgery in the IAC, the use of cooled irrigation at 7 °C and predrilling is recommended.

The knowledge and application of anatomy is essential for any professional involved in the evaluation, diagnosis, prognosis and treatment of the different alterations of the maxillofacial complex. The ignorance of the anatomical relationships of the inferior alveolar duct in the different surgical procedures can lacerate, compress or stretch the nerve generating lesions such as neuropraxia, axonotmesis and neurotmesis. The objective of this review is to describe the variations of the inferior alveolar duct course reported in the literature. There are 6 possible categories in which the variations of the CAI can be classified: 4 views in panoramic radiographs (two dimensions) and 2 views in computerized axial tomography (three dimensions). The inferior alveolar duct presents a great variability between patients and populations, which accentuate the product of tooth loss and alveolar reabsorption. Computed tomography of conic beam is the most suitable method for its evaluation.

BACKGROUND: The frequent anatomical variations of the inferior alveolar nerve (IAN) course should be considered prior to any treatment in this area. The aim of this study was to evaluate the course of the inferior alveolar canal (IAC) as it appears in the archived CBCT images of the mandible. MATERIAL AND METHODS: This cross- sectional study evaluated a sample of 156 CBCT examinations. The pattern of the IAC was evaluated and the prevalence of different patterns according to age and gender were recorded. In order to find the frequency of mandibular canal type among different ages, the patients were put into the three age groups (20-29, 30-44 and 45-59).The data were analyzed using Chi-square test and the significance level was set as p≤.05. RESULTS: Out of 156 patients, 52 canals was straight type, 52 had Catenary type and 52 of them were presented with Progressive descending type. There was not statistically significant difference between two genders (Pv=0.092). According to the type of the IAC course, there was a not statistically significant difference between the three age groups (Pv=0.32). CONCLUSIONS: Cone beam computed tomography is a useful method for precise assessment of the IAC course.

Introducción: Las lesiones iatrogénicas del nervio dentario inferior son complicaciones documentadas de diversos procedimientos quirúrgicos en la mandíbula. Debido a ello se justifica una descripción más detallada con referencias morfométricas de dicho conducto, como así también una correlación con imágenes. Materiales y métodos: Se realizó un estudio descriptivo observacional con una muestra de 44 hemimandíbulas secas y 100 tomografías computadas de mandíbulas de pacientes al azar. Se realizaron mediciones del foramen mandibular y mentoniano con respecto a bordes mandibulares. Se hicieron cortes en la rama y el cuerpo con sus respectivas mediciones. Se utilizaron Tomografías Computadas Cone Beam 3D de 100 pacientes las cuales fueron procesadas por el programa Compudent Navigator 3D®. Utilizando este programa se pudieron realizar las mismas mediciones que en los preparados anatómicos, como así también la reconstrucción del conducto. En una segunda etapa se realizó una correlación entre los valores morfométricos del estudio anatómico y se comparó con los estudios por imágenes (TC con reconstrucción 3D Dental Scan). Resultados: Se expresaron en tablas con diversas variables. Discusión: Los textos clásicos de anatomía y los libros de cirugía de la especialidad describen en detalle el recorrido y las relaciones del CAI, y presentan datos morfométricos pero no lo hacen en poblaciones locales. Como conclusión podemos afirmar que, tomando como punto de partida la anatomía y correlacionándola con la imagenologia, podemos llegar a evitar lesiones del nervio alveolar inferior en el transcurso de diversos procedimientos realizados en la mandíbula. Introduction: Iatrogenic inferior alveolar nerve injuries are documented complications of different surgical procedures in the jaw. It should justify a more detailed description with morphometric references of the duct and a correlation with images. Materials and method: A descriptive observational study with a sample of 44 dry hemijaws and 100 CT scans of patients. Measur-ements of the mandibular foramen and mental foramen with respect to jaw edges were made. Cuts in the branch and body were made with their respective measurements. Cone Beam Computed Tomography 3D (CBCT 3D) of 100 patients were processed by the Compudent Navigator 3D® program. The use of this program permited the same measurements done in the cadaveric jaws and the reconstruction of the duct. In a second stage we performed a correlation between the anatomic morphometric values compared with imaging studies (CT Dental Scan with 3D reconstruction) Results: They were shown in tables with different variables. Discussion: The classic texts of Anatomy and surgery books describe in detail the pathway and relations of the duct, and present morphometric data but not in local population. We may conclude that it is possible to avoid injuries of the inferior alveolar nerve during jaw surgery by considering the anatomy and its correlation with images.

Context: Better understanding of the anatomical location and course of the mandibular canal is necessary to avoid damaging inferior alveolar nerve. Aims: The aim of this study was to investigate the buccolingual course of the inferior alveolar canal (IAC) in different mental foramen locations, using cone beam computed tomography. Materials and Methods: Three hundred and twelve hemimandibular images were evaluated in this study. The location of mental foramen in relation to the apices of mandibular premolar and molar teeth were recorded. Nine measurements (in millimeters) were taken at the level of the IAC and posterior mandibular premolar and molar root apices. Relative distances of IAC to buccal and lingual mandibular cortex were calculated for different mental foramen types. Statistical Analysis Used: Data were analyzed by one-way analysis of variance and P < 0.05 was considered to be statistically significant. Results: The distribution of subjects according to the type of mental foramen includes: Type 1 = 50.3% (at the level of second premolar apex), Type 2 = 33% (between the apices of first and second premolars), and Type 3 = 16.7% (between the apices of second premolars and first molars). The buccolingual ratio of the IAC position was statistically significant in different mental foramen types (P = 0.00). Conclusion: The position of IAC was affected by the location of the mental foramen. The direction of IAC gradually changed from lingual to buccal and from posterior to anterior.

Inferior alveolar nerve repositioning is an option for treating the edentulous posterior mandible with insufficient bone height above the inferior alveolar canal. This report presents a case in which inferior alveolar nerve medialization was performed for placing dental implants. In the second postoperative week, mandibular fracture occurred after biting on a relatively solid piece of food, which was treated conservatively.

Background: Objective: The aim of this study is to evaluate the effect of slice thickness on the visibility of inferior alveolar canal (IAC) in cone‑beam computed tomography (CBCT) images. Materials and Methods: CBCT images of thirty patients (15 male and 15 female) with an age range between 40–50 years old were used. Cross‑sectional images were obtained with 0.5, 1, and 2 mm slice thickness and 2 mm interval. Two oral radiologists with at least 5 years’ of experience observed all of the 90 images and rated the images based on the visibility of IAC in a 4‑score classification (highly visible, visible, nearly visible, nearly invisible). Friedman test was used for the comparison of visibility of IAC in different slice thicknesses. To do the above test, the average of the scores of two examiners was calculated. A P. value below 0.05 was considered significant. Results: Visibility of IAC in different slice thicknesses of both raters showed no significant difference (P = 0.20). Conclusion: Within the limitations of this study the slice thickness has no effect on visibility of IAC in cross‑sectional images. Future studies on other multiplanar images are recommended Key Words: Cone beam computed tomography, cross,section, inferior alveolar nerve

The aim of the study was to evaluate the proximity of the mandibular third molar (M3) and the inferior alveolar canal (IAC) in a panoramic radiograph of 20-year-old subjects. The specific aim was to assess differences in this proximity over time. Two similar samples of panoramic radiographs taken in a routine oral health examination with 20-year time interval were examined retrospectively and images with both mandibular M3s were included. The material consisted of 300 subjects (25% men, mean age 20.5 +/- 0.6 years). The radiographic relationship between the mandibular M3 root and the IAC was assessed as follows: the M3 root was either apart from, tangential to, superimposed with, or inferior to the IAC. Differences between frequencies were tested using the chi-squared test. In the combined samples, only 16% of the M3s located apart from the IAC, 15% located tangential to, 61% superimposed with, and 8% inferior to the IAC. The proportion of the intimate locations had increased during the 20-year time interval from 79 to 88% (P

Paraesthesia of the lower lip during orthodontic treatment is rare. We present a case of unilateral temporary mental paraesthesia elicited by fixed orthodontic appliance therapy. The cause for the paraesthesia was thought to be close contact between the inferior dental nerve and the mandibular tooth roots. A cone beam computed tomography (CBCT) scan revealed intimate contact between the roots of the lower left second molar and the inferior alveolar canal. The use of imaging techniques to assess the relationship between the inferior dental nerve and tooth roots is discussed. Although anatomical relationships between nerves and tooth roots can be diagnosed using a variety of imaging techniques, CBCT is suggested as the imaging modality of choice as high-resolution images are produced at a relatively low dose to the patient.

Purpose To assess the clinical features of the inferior alveolar canal (IAC) using computed tomography (CT) and to analyze the significance of CT examination at third molar surgery. Materials and Methods A retrospective cohort study was performed involving 99 patients (145 teeth). The relationship between cortication status, buccolingual position, and shape of the IAC on the CT image and inferior alveolar nerve (IAN) injury after third molar surgery were statistically analyzed. Results The shape of the IAC was categorized into 3 groups: round/oval, teardrop, and dumbbell. IAN injury was observed in 7 of 145 cases (4.8%). All 7 cases exhibited absence of cortication; 3 were dumbbell shape and 4 were round/oval. According to logistic regression analysis of cases with absence of cortication, IAC shape was closely related to IAN injury. Conclusions These results suggest that assessment of the IAC shape and cortication status at third molar surgery may be clinically useful.

Purpose To verify the utility of computed tomography (CT) in preventing inferior alveolar nerve (IAN) injury owing to lower third molar extraction in close relation to the IAN on orthopantomogram. Materials and Methods A retrospective cohort study design of 150 lower third molar extractions was performed. Patients were divided in 2 groups: the CT group (n = 95) underwent panoramic radiography and mandibular CT and the control group (n = 55) underwent only panoramic radiography. Results Six extractions (4%) in the control group and 15 (10%) in the CT group resulted in IAN impairment (P > .05). Logistic regression models did not show that undergoing CT decreased the risk of IAN injury from lower third molar extraction. Conclusions Patient age and positive radiographic signs (darkening of the root and narrowing of the inferior alveolar canal) were associated with more requests for CT scanning. CT does not seem to significantly decrease the risk of producing IAN injury.

Background: A well awareness of the variation of inferior alveolar canal is mandatory to avoid iatrogenic complication. This study was conducted among 90 patients to determine variation in inferior alveolar nerve (IAN) loop through cone‑beam computed tomography (CBCT) images.Materials and Methods: CBCT images of 90 patients were involved in this study. All images were studied by the expert radiologist to see Type I, Type II, and Type III pattern of IAN canal (IANC). Results were subjected to statistical analysis for correct inferences. Results: Forty males and 50 females were included in the study. The difference was statistically nonsignificant (P = 0.5). Type I pattern was seen in 26 patients, Type II in 19, and Type III in 45 patients. The difference was statistically significant (P < 0.05). The most prevalent pattern was Type III (males ‑ 15 and females ‑ 30), followed by Type I (males ‑ 14 and females ‑ 12) and Type II (males ‑ 11 and females ‑ 8). There was statistical significance difference between males and females in Type II (P < 0.05).Conclusion: The anterior loop of IAC is quite common and IANC may show variation in structure. The most common pattern recorded was Type III. CBCT is very useful in the detection of IANC.Keywords: Anterior loop, cone‑beam computer tomography, prevalence

The purpose of this study was to determine the incidence of Inferior Alveolar Nerve (IAN) damage after surgical removal of lower third molars, to identify the cause and to construct a predictive model to assess the risk of IAN injury.Patients were selected from the out patient department after proper clinical and radiological evaluation of mandibular third molars. 50 mandibular third molars of 50 different patients were removed under local anaesthesia. Standardized data collection including the patient's name, age, gender, proximity of inferior alveolar nerve were recorded.A total 6% of the operated sides demonstrated impairment of labial sensation and vast majority of these disturbances subsided completely within six weeks.For IAN we found Patient's age, the development of roots, the degree of impaction and the radiographic position of the nerve canal to be significantly correlated to sensory deficit.

Purpose The aim of this study was to evaluate the effectiveness of coronectomy for teeth whose root apices are very close to the inferior alveolar canal. Patients and Methods The 43 patients of this study needed removal of their lower third molar, whose root apices were very close to the inferior alveolar canal. These patients underwent 47 coronectomies. Results The mean follow-up period was 9.3 months (range, 1 to 48 months). The mean total amount of root movement was 3.4 mm at 6 months, 3.8 mm at 12 months, and 4.0 mm at 24 months. Conclusions The technique of coronectomy is defined as removing the crown of a tooth but leaving the roots untouched, so that the possibility of nerve damage is reduced. Coronectomy is a preferable technique for patients who run a risk of injury to the inferior alveolar nerve during third molar surgery.

Purpose To predict the relationship between lower third molars and the inferior alveolar canal (IAC) from panoramic radiographs, and to establish criteria for using computed tomography (CT). Materials and Methods A retrospective cohort study was performed involving 443 patients (695 teeth). Predictor variables were the distance between the third molar and the IAC, and findings according to the Rood's criteria. Outcome variables were the absence of cortication between the third molar and the IAC on the CT image, and injury of the inferior alveolar nerve (IAN). Statistical analysis was performed to assess the relationship between predictor and outcome variables. Results All patients had preoperative panoramic radiographs, and 71 patients (119 teeth) also had CT images. On CT examination, 48 teeth (40.3%) showed absence of cortication. Injury of the IAN was reported in 7 cases (1.0%), 5 of which exhibited absence of cortication; the remaining 2 did not have CT scans. Five of the 48 cases showing absence of cortication exhibited IAN injury, and none of the cases with cortication exhibited IAN injury. On the panoramic images, the following signs were strongly correlated with absence of cortication: a superimposed relationship between the third molar and the IAC; darkness of the root; and diversion and narrowing of the IAC. Conclusion Presence of Rood's criteria was a predictor for a contact relationship between the third molar and the IAC, and an indication for CT examination. However, a superimposed relationship and the absence of Rood's criteria did not necessarily signify a separate relationship between third molar and the IAC.

Objective To determine the panoramic radiographic distance from the mandibular third molar tooth to the inferior alveolar canal. Study design Five hundred sixty mandibular third molars were evaluated by panoramic radiography. The teeth were grouped into erupted vs unerupted and further subdivided by tooth angulation. The distance from the most inferior aspect of the mandibular third molar tooth to the superior border of the inferior alveolar canal was measured with digital calipers. A t test was performed to compare erupted and unerupted teeth, and ANOVA was used to determine if a significant difference exists based upon tooth angulation. A record review was performed to assess the incidence of inferior alveolar nerve paresthesia based upon measured distances. Results The mean distance from erupted mandibular third molar teeth to the inferior alveolar canal is 0.88 mm. This distance was significantly different from unerupted teeth (P = .002). The mean values for unerupted teeth indicated that the most inferior portion of all teeth measured was below the superior border of the canal (negative values) as follows: mesioangular (−0.97 mm), vertical (−0.61 mm), distoangular (−0.31 mm), and horizontal (−0.24 mm). The position of mesioangular impactions were significantly different than all other impaction groups (P = .0125). The incidence of inferior alveolar nerve paresthesia was 3.33% (18/541), most commonly associated with mesioangular impactions (−0.66 mm) in female patients. Conclusions Unerupted mandibular third molar teeth are closer to the inferior alveolar canal than are erupted teeth. Mesioangular mandibular third molar impactions are most closely positioned to the inferior alveolar canal, and this may represent an independent risk factor for postoperative paresthesia.

The safe removal of third molars involved with the inferior alveolar canal (IAC) has been an area of concern since long. Many times we hesitate for the removal of third molars, fearing injury to the inferior alveolar nerve.The authors here describe a simple technique which can be used to remove third molars showing evidence of proximity to IAC on presurgical radiographic evaluation, as well as those root tips which, during removal, accidentally enter the IAC space.A step-by-step protocol is presented along with necessary precautions during the operative procedure.

We report on a 20-year-old Japanese man with mandibular prognathism and an abnormal position of inferior alveolar canal. This paper describes the surgical technique and modified intraoral inverted L ramus osteotomy used for mandibular setback. With this technique and examination by computed tomographic scanning, we could perform osteotomy as initially planned and avoid damage to the inferior alveolar nerve.

Background Preoperative radiographic examination of impacted mandibular third molars (IMTM) is essential to prevent inferior alveolar nerve injury during extraction. The purpose of this study was to evaluate the correlation between cone-beam computed tomography (CBCT) and digital panoramic radiography (DPR) findings in preoperative examination of IMTM. Methods This retrospective study included 298 teeth in 191 individuals. The relationship between the inferior alveolar canal (IAC) and the IMTM (buccal, lingual, interradicular or inferior), the position of the IMTM with respect to the IAC (contact, no contact), the morphologic shape of the mandible in the IMTM region (round, lingual extended, lingual concave), the type of IMTM (vertical, horizontal or angular) and the number of roots of the IMTM were evaluated on CBCT images. DPR images were evaluated for the number of roots of the IMTM and for the most common radiographic findings indicating a relationship between the IAC and the IMTM (darkening of the roots, diversion of the IAC, narrowing of the IAC and interruption of the white line). Data were statistically analyzed with Cramer V coefficient, Kappa statistic, chi-square and Fisher’s exact test. Results There was a significant difference in number of roots detected on DPR versus CBCT images. There was a significant association between the type of IMTM and the morphologic shape of the mandible on CBCT images. Darkening of the roots and interruption of the white line on DPR images were significantly associated with the presence of contact between the IMTM and the IAC on CBCT images. Conclusions Panoramic radiography is inadequate, whereas CBCT is useful to detect multiple roots of IMTM. When darkening of the roots and interruption of the white line are observed on panoramic images, there is increased likelihood of contact between the IMTM and the IAC. CBCT is required in these cases.