Cone beam computed tomography (CBCT) is the modern third dimension applied in the field of oral maxillofacial region. With lower radiation dose compared to conventional CT, its applications in dentistry has increased tremendously. Artefacts can seriously degrade the quality of computed tomographic (CBCT) images, sometimes to the point of making them diagnostically unusable. To optimize image quality, it is necessary to understand why artifacts occur and how they can be prevented or suppressed. CT artifacts originate from a range of sources; physical based, scanner based and patient based. This article highlights the causes of artefacts on CBCT images and methods to avoid them.

Aim of the study was to evaluate mandibular indices on a panoramic radiograph. A number of mandibular cortical indices, including the mandibular cortical index (MCI), mandibular cortical width (MCW) and panoramic mandibular index (PMI), AI (Antegonial index)was evaluated on Panoramic radiograph. Correlation between the indices were also done in our study and we found that PMI with MI and MI with AI were highly significant and showed similar results whereas MCI was non significamt with the other indices.

Purpose:To evaluate the significance of radiomorphometric indices, Panoramic Mandibular Index (PMI), Mandibular Cortical Index (MCI) and Antegonial index (AI) of the mandibular bone on panoramic radiographs and co-related with bone mineral density (BMD) for the diagnosis of postmenopausal osteoporosis. Methedology:Group 'A'-20 premenopausal women, Age range 30-55 years .Group 'B'-20 postmenopausal women, Age range 57-75 years Subjects for the study were selected through detailed case history, clinical examination and BMD scans (DXA machine-WIPRO (GE) LUNAR DPX DXA machine (version 10.5)) has been done for AP lumbar spine (L1-L4), Right and Left femur neck. Analysis of osteoporosis by T-score was done on the basis of WHO classification. Radiographic screening with OPG (Advapex 2000 (Xtropan imaging system version 2000) has been done. Subjects who fulfilled the given clinical and radiographic criteria were subjected to evaluation of radiomorphometric indices, Panoramic Mandibular Index (PMI), Mandibular Cortical Index (MCI) , and Antegonial index (AI) through OPG. Results:In our study Bone Mineral Density (BMD/T-scores) in Femur of Post-Menopausal group females T Score is-1.7 and Pre-Menopausal female groups T-score is-0.06. Interobserver agreement has taken for Panoramic mandibular Index, Antegonial Index, Mandibular Cortical Index. PMI is 0.29mm and 0.34mm , AI is 2.96mm and 3.58mm and MCI in class C 1 is 20% and 80% Class C 2 is 55% and 15% signifies presence of osteopenia Class C 3 is 25% and 5% signifies presence of osteoporosis for post menopausal and pre menopausal females respectively. Conclusion:In conclusion, the present study has proved a positive result in predicting osteoporosis by panoramic radiographs. Hence, panoramic radiographs seem to be a simple, inexpensive tool for screening of osteoporosis among the patients coming for dental evaluation.Our results demonstrate that although radiomorphometric indices are regarded as an ancillary method for the diagnosis of osteoporosis on panoramic radiographs

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