In dentistry, 3D printing already has diverse applicability, and holds a great deal of promise to make possible many new and exciting treatments and approaches to manufacturing dental restorations. Better availability, shorter processing time, and descending costs have resulted in the increased use of RP. Concomitantly the development of medical applications is expanding. (Zaharia et al., 2017)Many different printing technologies exist, each with their own advantages and disadvantages. Unfortunately, a common feature of the more functional and productive equipment is the high cost of the equipment, the materials, maintenance, and repair, often accompanied by a need for messy cleaning, difficult post-processing, and sometimes onerous health and safety concerns (Dawood et al., 2015)Low-cost 3D printers represent a great opportunity in the dental and medical field, as they could allow surgeons to use 3D models at a very low cost and, therefore, democratize the use of these 3D models in various indications. However, efforts should be made to establish a unified validation protocol for low-cost RP 3D printed models, including accuracy, reproducibility, and repeatability tests. Asaumi et al., suggested that dimensional changes may not affect the success of surgical applications if such changes are within a 2% variation .However, the proposed cut-off of 2% should be furthermore discussed, as the same accuracy may be not required for all types of indications. (Silva et al., 2008; Maschio et al., 2016)This aim of the present study is to evaluate the dimensional accuracy of the 3D printed mandibular models fabricated by two different additive manufacturing techniques, using highly precise one as selective laser sintering (SLS) and a low-cost one as fused filament fabrication and whether they are both comparable in terms of precision. In addition to evaluation of dimensional accuracy of linear measurements of the mandible in CBCT scans.7 mandibular models will be recruited. Radio-opaque markers of gutta-percha balls will be applied on the model to act as guide pointsTen linear measurements (5 long distances: Inter-condylar, inter-coronoidal, inter-mandibular notch, length of left ramus, length of right ramus; as well as 5 short distances: Length of the body of the mandible at midline, length of the body of the mandible in the area of last left molar, as well as that of the last right molar, the distance between the tip of right condyle to the tip of the right coronoid, as well as that of their left counterparts) will be obtained using digital calliper, to act as the reference standard later. Scanning of the model by CBCT will be next , 3D printing of the scanned image using SLS and FFF printers will be done. Recording of same linear measurment will be done on printed models. Comparison of the recorded values vs reference standard is the last step

To ensure the diagnostic ability of CBCT for caries detection under different types of tooth colored restorative materials. Material and Methods: In the present study a total of 80 extracted carious permanent molar teeth were selected. Caries was classified as grade 3 according to International Caries Detection and Assessment System (ICDAS) criteria. Half of carious lesions were removed from 40 molars as Control specimens. Carious teeth were randomly assigned into two groups and each group was divided into four subgroups including: two carious and two non-carious as controlled group and all the teeth were filled with different bioactive restorative materials, then all the specimens were scanned with cone beam computed tomography (CBCT) using a Promax ® 3DMid CBCT device (Planmeca, Oy, Helsinki, Finland). Results: Caries was detected in all the carious specimens of all the groups except that group A2 was much less remarkable than other groups. In the control specimens (noncarious) of all the groups: No caries was detected .Conclusion: Although CBCT is an excellent tool for secondary caries detection under different types of restorative materials but it should not be used as a primary diagnostic tool on regular basis. If its use is a must, so, optimized low dose low resolution protocol is recommended.

Aim: To demonstrate the validity of conventional CT and reconstructed 3DCT in assessment of mandibular fractures. A total of 14 mandibular fractures sustained by 10 patients were evaluated in the current work. All cases were males with ages ranging between 30-50 years. Patients were all assessed by 2DCT and reconstructed CT after compiling detailed history as well as thorough physical examination. The present study strengthens the role of the 3D-CT technique as a supplementary technique to the 2D-CT in the assessment of the mandibular fractures. 3DCT imaging has proved its validity as an exquisite tool in providing higher sensitivity in anatomic localization of mandibular fractures, in detecting comminution and bone displacement.

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Aim: This study was conducted to compare the diagnostic accuracy of CBCT imaging to digital panoramic imaging in assessment of osteoarthritic TMJ osseous changes. Methods: 25 patients were enrolled in the current investigation, divided into two groups, Group (1) the diseased group including fifteen patients. Group (2) the control group including Ten normal asymptomatic healthy patients (20 joints) but they were seeking for treatment of other dental problems, in the two groups enrolled in this study all participants were females with ages ranging between 25-55 years. All participants were scanned with panoramic and cone beam computed tomography (CBCT). Results: ROC curve analysis of panoramic views showed diagnostic accuracy 76.4% while diagnostic accuracy of CBCT (TMJ views) was 81.3% and CBCT (Sagittal views) showed 82.6% diagnostic accuracy. Conclusion: Panoramic images can be used as a preliminary valuable tool for evaluation of osteoarthritic osseous changes equivalent to CBCT images as it revealed relatively high sensitivity compared to CBCT images.