Quantitative Assessment of Mandibular Residual Ridge on Cone Beam Computed Tomography Image. Summary of the Doctoral Thesis

Abstract

Fundamental problem in prosthodontics is mandibular residual ridge resorption, resulting in decreased denture support, retention and stability as well as quality of life and satisfaction with new dentures. In severely resorbed anterior area of the mandible it is advisable to insert 2 to 4 dental implants and to make an overdenture. For dental implant planning and evaluation of residual ridge quantity, three - dimensional analysis, like cone beam computed tomography (CBCT), is required. In this scientific work 3 different studies were performed, including the same patient group that consisted of 45 edentulous female patients. In the first study 37 patients aged from 54 to 85 years (72.08 ± 8.53) were included. On the ground of the measurements performed on digital orthopantomogram (OPG) and CBCT sagittal images the amount of alveolar bone for dental implant planning in anterior area of the mandibular residual ridge was evaluated. It was found that digital OPG as only examination method for dental implant planning in severely reduced anterior area of the mandibular alveolar bone can result in inappropriate treatment plan and iatrogenic mistakes during surgery, in contrast to CBCT examination, where knife edge narrowing of the mandibular alveolar bone can be immediately diagnosed and dental implants accurately planned for further insertion. In the second study, where 38 patients aged from 54 to 83 years (70.08 ± 6.21) were included, reasons for mandibular alveolar bone narrowing were evaluated and general bone mineral density (BMD) was analyzed. BMD was determined in lumbar spine and femoral necks by dual energy x-ray absorptiometry (DXA), while the amount of mandibular bone was assessed by height and width measurements, performed on CBCT sagittal images. It was concluded that postmenopausal women with reduced general BMD do not appear to have a reduction in the size of the mandibular residual ridge. The third study had two parts. In the “group A”, where 37 patients aged from 54 to 85 years (72.08 ± 8.53) were included, correlation between mandibular residual ridge quantity, determined by measurements on digital OPG and CBCT sagittal scans, and satisfaction with mandibular conventional complete dentures, determined with visual analogue scale (VAS), was evaluated. It was concluded that there was moderate to weak correlation between patients’ satisfaction with mandibular conventional complete dentures and mandibular alveolar bone amount, assessed by CBCT, but not by digital OPG measurements. In the “group B”, where 25 patients aged from 56 to 79 years (69.02 ± 5.2) were included, changes in 3 years were analyzed, according to patients` satisfaction with conventional complete mandibular dentures and alveolar bone amount, detected by digital OPG measurements. It was found that despite reduction of mandibular alveolar bone in lateral regions, patients` overall dissatisfaction with conventional complete mandibular dentures decreased. This thesis consist of 100 pages, including 227 references. Additional copies of 3 documents are attached.