ABSTRACT
BACKGROUND: Surgical difficulty assessment in the extraction of impacted mandibular third molars is a constant challenge for oral surgeons. AIM: The first aim was to apply Maglione's new classification on patients that needed surgical extraction of impacted mandibular third molars, and the second aim was to study the correlation of the classification classes with the occurrence of postoperative neurosensory disorders. MATERIALS & METHODS: The present prospective clinical trial pilot study was conducted on patients attending oral and maxillofacial surgery clinics from February 2017 until January 2018 for the surgical extraction of impacted lower third molars. RESULTS: Fifty-one out of sixty-nine patients made the surgical removal of one impacted mandibular third molar. The most common subclass was 1B (24.6%), followed by subclass 3B (23.2%). Subclass 3A and 4B showed an equal distribution of (11.6%) each, and then subclass 2B (10%). The most significant subclass was 4B with (5.9%) neurosensory disturbance. None of the patients had a permanent disturbance. CONCLUSION: Maglione's classification offers unique detailed description of the buccolingual relationship of MTM with IAC that could be used as a future reliable radiographic guide to reduce the risk of post-operative neurosensory disturbances after MTM surgical removal.
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 < 0.001). CONCLUSION: Preoperative CBCT is recommended for cases showing interruption of canal wall; darkening of the roots or narrowing of the canal; or association between interruption and narrowing, diversion, or darkening of roots in a panoramic view. This study evaluated the risk relationship between the inferior alveolar nerve and impacted mandibular third molars, with the aim of reducing the occurrence of postoperative injury to the inferior alveolar nerve.
ABSTRACT
OBJECTIVES: This study has two main purposes: (1) to evaluate the effect of various clinically applied protocols [changing field of view (FOV), voxel size and tube voltage (kVp)] on CS 9300 CBCT (CareStream SM 749, Rochester, NY) image quality using its quality assurance test (QAT) phantom and (2) to evaluate the efficacy of a newly-designed prototype plugin on ImageJ (National Institutes of Health, Bethesda, MD) which was introduced to measure modulation transfer function (MTF) using a modified slanted-edge method. METHODS: Using a specifically constructed QAT phantom, five image quality parameters were assessed-image uniformity, signal-to-noise ratio, contrast, position checking and the MTF-for ten variables, clinically applied protocols on a CS 9300 PREMIUM three-dimensional CBCT device. RESULTS: With FOV and voxel size fixed, high-dose protocols resulted in less image noise and more uniformity. On the other hand, less image uniformity was achieved with less kVp. Moreover, high-dose protocols resulted in a high contrast-to-noise ratio (CNR). There were significant differences in CNR between 60 and 70 kVp as well as between 70 and 90 kVp. Our study identified no difference between MTF and either voxel size or FOV. CONCLUSIONS: The image quality of the CS 9300 CBCT varied with variability in exposure protocols and different voxel sizes. The negative association between greater spatial resolution (smaller voxel size) and the MTF shows that the slanted edge method is not ideal for MTF evaluation of CBCT and is therefore not recommended for using it for this purpose.
