| کلیدواژههای انگلیسی مقاله |
Panoramic radiographs, Nerve, Inferior alveolar, Mandibular nerve, IntroductionThe inferior alveolar canal (IAC) is a bony canal that starts from the mandibular foramen at the medial surface of the mandibular ramus and extends along the mandibular ramus from mandibular foramen in forward and downward directions to the mental foramen. Inside the mandibular canal, the inferior alveolar artery and nerve are present. The inferior alveolar artery provides blood supply to the mandibular teeth and related structures [ 1, ]. Understanding anatomical details of the IAC including position, course, and morphology is useful in mandibular impacted molar surgery, mandibular nerve block injection, mandibular bone resection, mandibular teeth root canal treatment, and other mandibular surgical procedures [ 2, - 3, ]. According to Liu et al. [ 4, ] study, the course of IAC can be divided into four groups, (1) Linear Curve, (2) Spoon Curve, (3) Oval Curve, and (4) Turn Curve. If vital structures such as inferior alveolar nerve and mental foramen are not accurately identified, many disorders such as altered sense of mandibular tissues, mandibular anesthesia, stinging, and pain in the mandible usually occur after surgery. In addition, damage to the related blood vessels, such as inferior alveolar artery or lingual artery, which may have a high potential for bleeding, can be a result of failure to identify the anatomical location of these structures. Therefore, detection of the position and configuration of the IAC and related anatomical structures is crucial for reducing such damage to this canal [ 5, ]. In some radiographs, the IAC has a cortical border, but in other radiographs, especially in patients with osteoporosis, it can be confused with bone marrow [ 6, ]. In addition, anatomical differences of the IAC may be a factor for failure of inferior alveolar nerve block injection [ 7, ]. Although the morphology and position of the canal vary in different ethnic groups and in different jaw types, these changes are often overlooked and cause problems in dental treatment. A detailed understanding of the factors affecting the anatomical changes in morphology of the canal can minimize this problem [ 8, ]. The purpose of this study was to investigate the course and direction of IAC in mandibular bone and its relation to anatomical factors such as gonial angle and location of entrance of IAC in the mandibular ramus.Materials and MethodIn this cross-sectional study, digital panoramic images taken from dental patients (2015-2017) were obtained from the archives of Oral and Maxillofacial Radiology Department, Faculty of Dentistry, Yazd, Iran. A total of 280 panoramic images were selected by random sampling. All samples have been selected from Iranian population and composed of men and women aged 18-60 years. The type of IAC course was diagnosed by visual detection and comparison with references. Panoramic images had been taken by Planmeca-Promax (Helsinki, Finland) with the same conditions (80 kvp, 12mA, 18 s). Planmeca Romexis Viewer 451R (Helsinki, Finland) software was used to evaluate the course of the inferior alveolar canal, gonial angle, and IAC insertion. These factors were evaluated in left side of each patient.According to the study of Liu et al. [ 4, ], the course of IAC was classified into four categories based on its appearance on panoramic radiography defined as Type (1) linear curve (right) , a canal that is in contact or in close contact or maximum at a distance of 2 mm to the apex of the first mandibular molars Type (2) spoon-shaped curve, canal that is in contact or in close contact or maximum at a distance of 2 mm to the inferior mandibular cortex Type (3)oval curve(curved), the status between modes 1 and 2 (position intermediate) and Type (4) turning curve( angled) (Figure 1,).Figure 1. Types of canalsMeasurements were performed using Romexis Viewer software on the Panoramic Digital Imaging Processor on computer at Yazd Dentistry School by selecting the ruler menu and the angle measurement menu and drawing lines in the desired areas.Gonial Angle MeasurementThe gonial angle was measured on a degree scale and recorded in a checklist. Gonial angle was measured by measuring the angle resulting from the collision of two tangent lines on the mandibular inferior border and posterior ramus border [ 9, ] (Figure 2,).Figure 2. Gonial angleIAC entry pointTo check the canal entry point, the distance from the condylar most upper point to the mandibular angle was categorized into three equal parts as the upper, middle, and lower parts. Then the canal entry location was classified according to the specific region it was in, and recorded in the checklist [ 10, ] (Figure 3,). Figure 3. Inferior alveolar canal origin locationAfter observing all samples, data on patient gender and type of canal course were recorded in a checklist. Data were analyzed by SPSS software version 20 Chi-square, ANOVA and t test were used for data analysis.ResultsThis study was performed on 280 digital panoramic images from the Department of Radiology, Shahid Sadoughi Dental School, Yazd. The mean age of the samples was 35.58&,plusmn 10.66 with a range of changes from 18 to 60 years. 155 samples were female (55.4%) and 125 samples were male (44.6%).The results showed that the most common type of canal was curved type (69.28%) and the less common was spoon type (6.78%). In this regard, in all age groups, the most common type of canal was curved type. These differences were tested by the Chi-square test, with p= 0.113, which is not significant, which means different types of lower alveolar canal in different age groups were identical (Table 1,). Also in evaluation of the frequency distribution of lower alveolar canal types according to gender, the same results were obtained (p= 0.113) so that different types of lower alveolar canal in two genders were identical. The most common type of canal in men and women was the curved type and the less common type was spoon and right type, respectively (Table 2,). Type of canalRight n (%)Angled n (%)Curved n (%)Spoon n (%)Total n (%)Age Group20-294 (4.2)14 (14.8)69 (73)7 (7.4)94 (33.5)30-3910 (9.4)19 (17.9)72 (67.9)5 (4.7)106 (37.8)40-497 (14)6 (12)33 (66)4 (8)50 (17.8)50 and above5 (16.6)2 (6.6)20 (66.6)3 (10)30 (10.7)Total n264119419280p= 0.113 |
| نویسندگان مقاله |
Ali Derafshi |
Postgraduated Student, Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Khalil Sarikhani |
Oral and Maxillofacial Radiologist, Shiraz, Iran.
Farzaneh Mirhosseini |
Oral and Maxillofacial Radiologist, Yazd, Iran.
Motahareh Baghestani |
Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Roghayeh Noorbala |
Dentist, Yazd, Iran.
Motahareh Kaboodsaz Yazdi |
Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
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