Mandibular Bone Tissue Assessment in Patients with Single Remaining Teeth Usingcone-Beam Computed Tomography

During recent decades in order to increase the amount of diagnostic information and reduce radiation dose exposure during examination computed diagnostic methods were widely used in dental practice. This study was aimed to determine indications for overdentures application in patients with single remaining teeth on the lower jaw, based on bone quality and abutment teeth status assessment, using cone-beam computed tomography (CBCT). Materials and methods. 18 patients (13 female and 5 male) aged from 56 to 76 years with single remaining teeth on the lower jaw were examined on Point 3D Combi 500 cone-beam computed tomography with three dimension high definition image analysis and multilane reconstruction using 9х12 sm planar sensor for scanning (radiation level 30-100 mcZv). Three dimension maxillo-facial bone structure reconstruction was made using Real Scan software. “Profile” function particularly determined cortical and trabecular bone tissue density in region of interest according to Hounsfield scale (from -1024 to 3071 units). Results and discussion. Using panoramic view mode, configuration of mandibular residual ridge was estimated bilaterally. 9 of 18 patients were diagnosed with H.I. Elbreht's class 4 severely atrophied ridge, 5- with class 4 moderately atrophied ridge, 2- with class 3 moderately atrophied ridge and 2 of them with class 1 severely atrophied ridge. Eight patients presented with two canine teeth remained, five - with two canines and incisors and five - with one remaining canine. By tomogram slice thickness changing and gray scale range correction, in three of five patients with one remaining canine tooth, loss of 1/3 of cortical alveolar bone (in 2-the vestibular part, in 1- the lingual part) was detected. In four patients periodontal structure changes- periodontalfissure irregular dilatation over 1 mm and periapical bone destruction sized 2-3,5 mm (symptoms of chronical periodontitis) were displayed. There were radix perforations detected in two of five patients with two canines and incisors preserved, in four of them periodontal structure changes- periodontalfissure irregular dilatation over 1 mm and periapical bone destruction sized 2-4,3 mm. In two of eight patients with two remaining canines loss of 1/3 of cortical alveolar bone (vestibular/lingual part) was detected. In three patients changes of the remaining teeth periodontal structure were visible - periodontalfissure irregularly dilated to 1-2,5 mm and periapical bone destruction sized 2-3,7 mm. In three patients no periodontal structure changes were detected. Contraindications for overdentures application were determined in three patients. In two of them with single remaining canines loss of 1/3 of vestibular cortical bone was displayed with periapical bone destruction of spherical shape, sized 3-3,5 mm (symptoms of chronical periodontitis), H.I. Elbrecht's (1958) type IV residual ridge bilateral atrophy with low bone density zones. A patient with two remaining canines presented with tooth 33 radix perforation on vestibular side, tooth 43 - periapical bone destruction of spherical shape, sized 4,3 mm (symptoms of chronical periodontitis) and H.I. Elbrecht's (1958) type IV residual ridge bilateral atrophy with bone density reduction. Conclusion. According to the results of 18 patients with single remaining teeth on the lower jaw examination using mandibular CBCT, indications for overdentures application were determined in 15 of them—those persons with consistent structure of cortical and trabecular residual ridge bone, without density decrease and signs of periodontal pathological changes.