Influence of orthodontic brackets and permanent retainers on the diagnostic image quality of MRI scans: A preliminary study.

BACKGROUND: Orthodontic treatment with fixed mechanotherapy using appliances and permanent retainers bonded after treatment is a routine procedure performed in clinical dentistry. Patients with braces or retainers sometimes need to undergo magnetic resonance imaging (MRI) for various reasons. Radiologists do not know the exact impact of the materials used in orthodontics on the diagnostic image quality of MRI scans. OBJECTIVES: The aim of the study was to evaluate the influence of different types of orthodontic brackets and permanent retainers on the diagnostic image quality of MRI scans. MATERIAL AND METHODS: Twenty patients with bonded brackets (stainless steel buccal/labial, stainless steel lingual, ceramic self-ligating with metal slots, ceramic, and polycarbonate) and 18 patients with bonded fixed retainers (titanium, fiber-reinforced composite, multi-stranded stainless steel, and different combinations of permanent retainers) participated in the study. The same adhesive was used for bonding. Cranial MRI scans of 6 regions were acquired for each subject, using a 1.5T MAGNETOM machine. Six radiologists evaluated the images and provided scores based on the modified receiver operating characteristic (ROC) analysis of distortion. The paired Wilcoxon signed-rank test was used to assess differences between the materials and the anatomic sites with regard to the distortion rating scale. Cohen's kappa coefficient (κ) was applied to establish the interrater reliability. RESULTS: A statistically significant difference was found between stainless steel brackets (both buccal/ labial and lingual) and all other experimental materials in terms of mean distortion scores (p = 0.020 or p = 0.024). The interrater reliability proved to be high. CONCLUSIONS: Stainless steel buccal/labial and lingual brackets caused maximum distortion of the images, which became non-diagnostic; hence, such brackets should be removed before MRI. Ceramic and polycarbonate brackets as well as fiber-reinforced composite retainers did not distort the images; thus, they need not be removed. Ceramic self-ligating brackets with metal slots, titanium retainers, multi-stranded stainless steel retainers, and combinations of fixed retainers caused minimal distortion; however, the images were still diagnostic. Hence, patients using these materials may not need to have them removed before MRI.

Sonographic imaging of fibrosis of oral mucosa and its correlation with clinical staging in oral submucous fibrosis.

BACKGROUND AND OBJECTIVES: To evaluate the efficacy of ultrasonography (USG) as a noninvasive tool in assessing the severity of oral submucous fibrosis (OSMF) by measuring the submucosal thickness and also to correlate the sonographic changes with clinical staging. MATERIALS AND METHODS: The submucosal thickness of the upper and lower labial mucosa, anterior and posterior portions of the right and left buccal mucosa were measured using ultrasound in 64 patients comprising of 32 OSMF patients and 32 controls. Among the controls, 16 were with a habit of chewing gutkha and 16 were without any habit history. RESULTS: In OSMF group, four patients were with Stage I, 13 were with Stage II, 11 were with Stage III, and four with Stage IV. Results were analyzed by one-way analysis of variance for the significance of difference among the groups in submucosal thickness. As the stages of OSMF advanced, there was an increase in submucosal thickness of the buccal mucosa in the study group when compared with controls (P< 0.005). CONCLUSION: USG is an effective noninvasive zero radiation tool for assessing the progression of OSMF.