Interruption Of White Line Research Articles

Comparison of Digital OPG and CBCT in Assessment of Risk Factors Associated with Inferior Nerve Injury during Mandibular Third Molar Surgery.

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.

Comparison of panoramic radiograph and cone beam computed tomography findings for impacted mandibular third molar root and inferior alveolar nerve canal relation.

This study was aimed at determining the specific signs of close relationship between impacted mandibular third molar (IMTM) root and inferior alveolar nerve (IAN) canal as visualised on digital panoramic radiograph or orthopantomograph (OPG) which should indicate as well as contraindicate the need for cone beam computed tomography (CBCT) imaging based on hierarchical model of Fryback and Thornbury. The sample consisted of 120 individuals (200 IMTM) who had undergone OPG as well as CBCT imaging as preoperative radiographic evaluation before surgical extraction. On panoramic radiographs; Rood and Sheehab's radiographic signs of IMTM root and IAN canal, impacted third molar position based on Winter's classification and depth of impaction based on Pell and Gregory's classification were evaluated. On CBCT; presence/absence of corticalization and the status of the buccal and lingual cortices (thinning/perforation) were evaluated. These findings of OPG were compared to CBCT findings to determine the better modality based on hierarchical model of Fryback and Thornbury. Statistically significant association was found between radiographic signs of Rood and Sheehab such as 'no relation' and 'superimposition' on OPG and presence of corticalization between IMTM root and IAN canal on CBCT. Statistically significant association was also found between 'mesioangular' and 'vertical' positions of Winter's classification as well as 'class 1A' of Pell and Gregory's classification of IMTM on OPG and presence of corticalization on CBCT. CBCT was found to be having lesser variance and greater F value as compared to OPG for evaluation of IMTM. On OPG; Rood and Sheehab's radiographic signs such as 'no relation' and 'superimposition', Winter's 'mesioangular' and 'vertical' and Pell and Gregory's 'Class 1A' are not indicative for CBCT examination before surgical extraction is attempted. On OPG; Rood and Sheehab's radiographic signs such as interruption of white line, darkening of root, darkening of canal, deflection of root, narrowing of canal as well as diversion of canal are all frequently associated with absence of corticalization between IMTM root and IAN canal and hence require CBCT examination before surgical extraction is attempted so that post-operative neurological complications can be minimised. Also, Winter's horizontal, distoangular and others as well Pell and Gregory's classes 1B,1C,2A,2B,2C,3A,3B,3C are indicative for CBCT examination before surgical extraction is attempted. Fryback and Thornbury model-based comparison proves that CBCT is a better radiographic modality as compared to OPG for evaluation of IMTM relation with IAN canal.

Correlation of panoramic high-risk markers with the cone beam CT findings in the preoperative assessment of the mandibular third molars

Background/purposePreoperative radiographic examination of mandibular third molars (MTM) is essential to prevent inferior alveolar nerve (IAN) injury. The aim of this study was to assess the panoramic radiography (PAN) signs considered as indicators of increased risk of IAN injury and to correlate them with the cone beam CT (CBCT) findings. Materials and methods58 patients who had MTMs extraction between January 2012 and January 2018. OPG were evaluated for the following signs: interruption of the roof of the canal, root darkening, roots deflection and narrowing, canal deviation, superimposition between the MTM roots and mandibular canal. Loss of canal cortication, root grooving, thinning and perforation of lingual cortex were assessed in CBCT images. Chi-square test and multivariate logistic regression tests were used to test the relationship between PAN signs and CBCT findings. ResultsA total of 79 MTMs were examined. Loss of canal cortication in CBCT was seen in 22 (27.8%) of the cases. Root darkening in PAN images was the most frequent radiographic sign. Canal deviation and interruption of white line in PAN demonstrated a statistically significant correlation with the loss of canal cortication between the MTM and the mandibular canal on CBCT images (p = 0.004 and p = 0.012, respectively). No statistically significant association was observed for the other PAN signs and CBCT findings. ConclusionCanal deviation and interruption of white lines were associated with loss of canal cortication on CBCT, indicating a direct contact between the roots and the mandibular canal which required a further assessment prior to the extraction.

Inferior alveolar nerve injury: Correlation between indicators of risk on panoramic radiographs and the incidence of tooth and mandibular canal contact on cone-beam computed tomography scans in a Western Australian population.

The aim of the present study was to assess risks prior to third molar removal. A 2-D panoramic radiograph or a 3-D cone-beam computed tomography (CBCT) scan can be used to visualize the proximity of the third molar to the mandibular canal. We aimed to correlate panoramic indicators of risk with the incidence of contact between these two structures on CBCT scans. Patients were selected from a Western Australian population if they had a panoramic radiograph that illustrated signs of risk of inferior alveolar nerve injury and had a CBCT scan on file. Statistically-significant relationships between the relative position and distance between the mandibular canal and third molar were investigated using χ2 -test and Fisher's exact test in Stata version 13. Within the Western Australian sample (N=100), of six possible panoramic indicators of risk, two were significantly associated with contact between the tooth and mandibular canal on CBCT: (a) interruption of the radiographic white line of the canal; and (b) darkening of the root(s). Two panoramic radiograph risk signs are significantly more likely to indicate contact on the CBCT scans: interruption of the white line and darkening of the root(s). Further research is required to develop CBCT prescription guidelines for surgical planning.

Role of Panoramic Imaging and Cone Beam CT for Assessment of Inferior Alveolar Nerve Exposure and Subsequent Paresthesia Following Removal of Impacted Mandibular Third Molar.

Pre-operative radiographic evaluation of impacted mandibular third molar and inferior alveolar canal (IAC) is important in preventing a possible nerve exposure and damage during surgical removal. The present study analysed the relation of the mandibular third molar with inferior alveolar canal using panoramic radiography (PAN) and cone beam CT (CBCT) and evaluated the radiographic features suggestive of IAN exposure and post-operative paresthesia. PAN and CBCT findings of 53 impacted mandibular third molars having a close relation with IAC undergoing extraction were analysed. Further, all cases were evaluated for any sensory loss in relation to IAN 1week post-operatively. The most common PAN feature was combination of darkening of roots (DR) and interruption of white line (IWL), seen in 35.86% (19) cases. The most common CBCT feature was thinning of lingual cortex in 81.14% (43) cases. The most common location of IAC in CBCT was inferior in 47.16% (25) cases, followed by buccal 26.41% (14). On comparison of PAN and CBCT findings, DR and IWL both exclusively 92.86% (13); 80% (12) cases and in combination 75% (15) were most commonly associated with thinning of lingual cortex. IAN exposure was seen in 7.55% (4) cases, and 3.77% (2) cases reported with paresthesia. Absence of corticalisation and IWL was associated with all cases of nerve exposure, inter-radicular location of IAC seen in three out of the four cases. Cases with paresthesia had DR and deflection of roots (DEFR) with thinning of lingual cortex by roots. DR with DEFR or IWL in PAN as combination and inter-radicular location of IAC with thinning of lingual cortex by root tips in CBCT are highly predictive of nerve exposure and subsequent paresthesia.

Necessity of CBCT - examination in assessment of the surgical approach for the extraction of impacted lower third molars

Aim: The aim of this research is to demonstrate the necessity of CBCT - examination for evaluation of the surgical approach of high risk impacted lower third molars. As `high risk` we defined lower third molars which have signs of proximity to the mandibular canal seen on standard panoramic radiography. Material and methods: All patients who had undergone a CT examination between september 2015 and october 2016 were reviewed. We included images from conical-beam computed tomograph made in the Department of radiologic diagnose, University medical and dental centre of the Medical university of Varna. The device used is Planmeca ProMax 3D Max with software for images Planmeca Romexis. We chose 100 images randomly. From these images we selected 39 images with high-risk lower third molars. We examined different signs with which we defined the exact position to the mandibular canal of 60 wisdom teeth and we managed to asses the risk of damaging the IAN during a classical odontectomy of these teeth. In the research we included the panoramic radiographs of 20 patients from these 39 cases. Results: From the examination of the CBCT images we found: 28 lower third molars where the mandibular canal runs apical and have contact; 11 where the mandibular canal runs apical in contact with the tooth and it`s seen penetration of the apices of the tooth; 10 where the mandibular canal runs buccal with contact; 8 where the mandibular canal runs lingual with contact; 3 where the mandibular canal runs between the roots touching one/both of them. In three of the cases we found severe deviation of the root apices. From the examination of the panoramic radiographs we found: 5 cases with darkening of roots in the apical area; 8 with interruption of white line (lamina dura) of the mandibular canal; 1 with diversion of the mandibular canal with/without narrowing of the mandibular canal; 6 without any of these three signs. Conclusion: The development and rapid commercialization of new technologies like CBCT allows us to have precise images and exact diagnosis of the diseases in the oral and maxillofacial area. Our study confirmed the high diagnostic value of CBCT regarding to precise the position of the lower third molars to the mandibular canal and IAN. This gives the clinician the opportunity to determine which lower third molars are `high risk` teeth and to choose the best method for surgical treatment.

Assessment of proximity of impacted mandibular third molar roots to the mandibular canal using intra oral periapical radiography and cone-beam computerized tomography: A comparative study

Objective: To assess the reliability of fi ve intra oral periapical radiography (IOPAR) radiographic signs, and to compare the reliability of IOPAR with that of cone-beam computerized tomography (CBCT) for determining the proximity of impacted mandibular third molar and mandibular canal. Methods: The present study consisted of 50 subjects, in age group of 18-30 years with impacted mandibular third molar visiting the department, Oxford Dental College and Hospital, Bengaluru. Relationship of impacted mandibular third molar with the mandibular canal was assessed using IOPAR signs and CBCT fi ndings. The 5 radiographic signs i.e. darkening of roots, diversion of canal, narrowing of canal, presence of cortication, and interruption of white line seen on IOPAR, were correlated for the proximity and involvement with CBCT fi ndings for the same. Results: In this study only 4% (2) subjects showed absence of corticalization on CBCT compared to diff erent radiographic (IOPAR) signs in all subjects. Among these two subjects diagnosed with an absence of corticalization, 50% (1) presented with a radiographic sign of darkening of roots and both i.e. 100% (2) presented interruption of white lines on IOPAR the mean and SD values of distance from mandibular third molar root to mandibular canal were 2.25 and 1.48 respectively in CBCT. Conclusion: This study showed the poor reliability of radiographic signs of IOPAR predicting the proximity of mandibular third molar root with mandibular canal related to CBCT fi nding. This creates the controversy and questions regarding the radiographic signs of IOPAR reliability with CBCT fi ndings that was found far more precise and accurate as per for future prospects.