Objectives: To investigate the presence, the number, the anatomic location, the course and morphology of median lingual canals in edentulous patients using cone beam computed tomography (CBCT). Subjects and methods: Fifty completely edentulous patients were recruited from the outpatient clinic of the Prosthodontics Department, Faculty of Dentistry, Cairo University. All patients in this study were seeking to improve the retention of their mandibular complete dentures through dental implants. Patients were of age ranging from 50 to 70 years. A CBCT scan was performed for all patients to evaluate the edentulous area prior to implant placement. The number, the anatomical location and morphology of the median lingual canals were assessed by two Oral and Maxillofacial Radiologists. Additionally, the slope of the canals, the distance between the alveolar crest and the terminal ends of the median lingual canals; the length and the diameter of the median lingual canals were also assessed. Results: All patients had at least one median lingual canal. Supra-spinosum canals were more frequent than infra-spinosum canals. Regarding the anatomical lingual canal morphology, Type E, A and D showed the greatest frequency. Most of the supra-spinosum canals sloped downward toward the labial surface, while most of the infra-spinosum canals sloped upward toward the labial surface. The distance between the buccal terminal end of the canal and the alveolar crest ranged between (3.6-21.2 mm) for supra-spinosum canals and (9.4-24.8 mm) for infra-spinosum canals. The distance between the lingual terminal end of the canal and the alveolar crest ranged between (2.7-19.4 mm) for supra-spinosum canals and (10.8-30.4 mm) for infra-spinosum canals. The canal length was found to be (3.5-15.3 mm) for supra-spinosum canals and (2.4-10.2 mm) for infra-spinosum canals. The average diameter of all canals ranged between (0.4-1.2 mm). Conclusions: Determination of the number, the position as well as the diameter of median lingual canals before mandibular midline implant surgery in edentulous patient is important as these canals are constant anatomical landmark which have both vascular and neurosensory components.

Introduction: Cone beam computed tomography (CBCT) is an imaging modality of great value in dental field thanks to its lower radiation and high spatial resolution compared to Computed Tomography (CT). However there is still some controversy of using CBCT in bone density assessment. That is why this study was conducted to assess the ability of the gray scale values driven from CBCT by different milliamperage (mA) settings to assess bone density. Methodology: Seventeen mandibles were included in this study. On each mandible, a gutta percha marker was glued on the buccal surface of bone and another one on the same site on the lingual surface then covered by a layer of pink wax of thickness 13-17mm to simulate soft tissue in patients imaging. The mandibles were fixed to their skulls and imaged by a CBCT machine Planmeca ProMax 3D Mid ® with three different mA settings (8, 10 and 12 mA). For the resultant images, both corrected coronal images marked with gutta percha marker and others away from gutta percha marker were assessed and the measured gray scale values were tested for agreement between 3 scans. Results: Changing of current intensity from 8 mA to 10 mA leads to a change of measured bone density by 24% in cuts away from radiopaque markers and 26% in cuts marked with radiopaque markers. Changing of current intensity from 8 mA to 12 mA leads to a change of measured bone density by at least 18 % in cuts away from radiopaque markers and at least 21% in cuts marked with radiopaque markers. Bland-Altman limits of agreement show clinically poor agreements between the measured densities. Conclusion: Changing of milliamprage (mA) setting from 8 mA to 10 or 12 mA will change the gray scale values denoting bone density in a statistically significant manner making bone density assessment from CBCT inaccurate.

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Introduction: Completely edentulous patients usually have many problems associated with their mandibular complete dentures. Dental implants solved many of these problems. Many attachments are used nowadays to retain mandibular overdenture to dental implants. Among these attachments are the low profile locator and equator attachments. This study was conducted to study the effect of both attachments on bone level around two implants retaining complete mandibular overdenture. Methodology: This study was conducted on 10 completely edentulous patients. Two implants were installed in the canine region bilaterally for all patients. Patients were then randomly divided into two groups where the first group received implant supported mandibular overdenture retained by locator attachment, while the other group received implant supported mandibular overdenture retained with equator attachment. The patients were then referred to oral and maxillofacial radiology department, Faculty of Dentistry, Cairo University for radiographic assessment to measure the bone height and density changes around the implant at the day of overdenture delivery and 12 months later. Results: In the current study, bone height changes in both groups was in the clinically permissible range. Regarding bone density, it increased gradually around the loaded implants in both groups. When density is compared between the two groups, the locator attachment group showed significant increase when compared to the equator attachment group after 12 months of prosthetic loading. Conclusions: Within the limitation of this study, both locator and equator attachments are viable treatment options to retain an implant supported mandibular complete overdenture regarding hard tissue response around the implants but more studies with more extended follow up is recommended.