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Statement of the problem: The use of narrow diameter implant to retain an implant overdenture could be the treatment of choice to restore resorbed mandibular ridge, however its success or failure depends on the amount of stresses transferred to the surrounding bone via the selected attachment system. The goal of this study was to evaluate the stress distribution around two narrow- diameter titanium-zirconium implants retaining mandibular overdenture with novel Novaloc attachment system in comparison with traditional locator attachment using 3 D finite element analysisMaterials and methods: Two 3D finite element models were prepared simulating completely edentulous mandibular ridge with complete overdentures supported by two narrow diameter implants in the canine region. Model 1,represented implants with locator attachment while Model 2, represented implants with Novaloc attachment. The models’ components were created on a commercial CAD/CAM package then imported to finite element software. Load of 100 N was applied on molar area of the mandible vertically and oblique Load of 50 N at 30o and 45o angle. Results: Within the limitations of this research, similar deformations and stresses distributions were reported in the bone and implant complex with a little more stresses in the Novaloc system. All values found were within acceptable physiological limits of the studied parts. Stress received by the PEEK matrix of the Novaloc attachment was significantly less than that of the locator nylon cap. Conclusion: Within the limitations of this in-vitro study it may be concluded that locator attachments may provide little less stress on the bone and implant complex in implant retained overdenture than did the Novaloc attachment. However, the lifetime of the flexible caps may be longer for Novaloc system in comparison to locator ones.

Objective: The purpose of this RCL was to evaluate bone height changes around hybrid implants in three implant- retained mandibular overdenture with locator attachment.Materials & Methods: Ten completely edentulous male patients were enrolled in this study. Preoperative Cone beam computed tomography (CBCT) had been made to evaluate bone height & density in areas for implant installation. Patients had received three hybrid implants installed in midline & mandibular canine areas following flapless technique. Implants were early loaded; two weeks after implant installation. Overdentures were functionally fitted onto the locator attachment of the hybrid implants by direct pick-up technique.Evaluation: Bone height changes were evaluated with the aid of CBCT at the time of implants’ loading, six months and twelve months later. Mesial & distal crestal bone heights were calculated from reconstructed corrected sagittal views.Results: The results had revealed that there was no significant difference in peri-implant bone level throughout the follow-up periods on comparing the three implant sites. However, there was slightly higher bone resorption around the distal implants than the midline ones.Conclusions Three implant retained overdentures with locator attachments may preserve peri-implant bone in the anterior mandibular area. Midline implant in three implant overdentures may not be subjected to more stresses than the two distal implants

Objective: The purpose of the this study was to evaluate the oral microbial adhesions and quality of life in Maxillectomy patients after rehabilitation with two types of maxillofacial obturators: Thermopress & Cobalt- Chromium obturators.Materials and Methods: Type of study: Randomized clinical trial (RCT) Ten hemi-maxillectomy patients were taken from the out-patient clinic of the national Institute. Patients Grouping: Patients were randomly divided into two equal groups. Group-I: Five patients had received thermopress obturators. Group–II: patients were rehabilitated with cobalt chromium & polymethyl methacrylate obturators. - Microbial adhesions of viable microorganisms in the accumulating biofilm layer on Polymethylmethacrylate (PMMA) & Thermopress obturator bulb surfaces were determined along four weeks period & converted to Colonies Forming Units (CFU) per cm2 unit surface area . -QOL was evaluated according to the Obturator Functioning Scale’ (OFS). questionnaire by direct interviews with the patients at the end of four weeks period.Results: The results of this study revealed that the microbial adhesions showed statistically significant increase in Group-I patients compared to Group-II; On the other hand, the patient’s quality of life in Group-I recorded higher values in the examined domains than Group- II patients.Conclusion: Within the limitations of this study; it may be concluded that: Thermopress material may induce more microbial adhesions than Cobalt chromium &PMMA ones. Thermoplastic obturators may provide maxillectomy patients better esthetics, speech & social interaction than metalic obturators with conventional PMMA.