Saudi Cultural Missions Theses & Dissertations
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Item Restricted Survival Rates, Technical Complications and Dimensions of Monolithic Zirconia Fixed Complete Arch Dental Prostheses(Tufts University School of Dental Medicine, 2024) Malluh, Ahmad; Papaspyridakos, Panos; Vazouras, Konstantinos; Finkelman,Matthew; Kudara, Yukio; Papaspyridakos,PanosOBJECTIVE: The primary objective of this study was to assess the survival and complication rates of monolithic zirconia implant-supported fixed full dental prostheses (IFCDPs) in completely edentulous patients following a minimum 1-year clinical follow-up. Additionally, the study sought to evaluate associations between risk indicators, structural dimensions, and quality-of-life outcomes. MATERIALS AND METHODS: This observational, single-center retrospective cohort study included a convenience sample of 44 participants who received 61 zirconia IFCDPs at Tufts University School of Dental Medicine (TUSDM). Data on demographics, clinical variables, technical complications, and prosthesis dimensions were collected. Descriptive statistics were calculated, and associations between independent variables and complications were analyzed using generalized estimating equations (GEE). Statistical analyses were performed using SPSS v.28 (IBM Corp., Armonk, NY, USA) and SAS 9.4 (SAS Institute Inc., Cary, NC, USA). RESULTS: The study included 44 participants (45.5% female, 54.5% male; mean age 67.07 (SD=12.1) years) with a mean prosthesis use duration of 28.67 (SD=18.32) months. The majority (72.7%) did not use a nightguard, and 25% reported bruxism. Opposing dentition included natural teeth (13.1%), implant-supported prostheses (50.8%), removable prostheses (14.8%), a combination of teeth and implants (19.7%), and implant overdentures (1.6%). Of the 61 prostheses, 52.5% were maxillary, and 47.5% were mandibular. Minor technical complications included Ti-base decementation (13%), chipping (12%), loss of access hole material (13%), and wear of prosthetic screws (11.5%). Major complications were infrequent, with fracture of screws (2%) and fracture of frameworks (3%). The overall prosthesis survival rate was 93.44%, with a mean total complication rate of 0.8 (SD=1.15)events per prosthesis. Structural analysis identified reduced dimensions at critical cross-sections as potential contributors to fractures. CONCLUSION: This study demonstrated a 93.44% survival rate for monolithic zirconia IFCDPs over an average follow- up period of 28.67 months. While the prostheses showed high reliability, minor technical complications were relatively common, highlighting the need for routine maintenance. The findings underscore the importance of prosthesis design and risk factor consideration in treatment planning. Larger, multicenter studies with longer follow-up periods are recommended to validate these findings and provide greater insights into the long-term performance of zirconia prostheses.22 0Item Restricted Effect of Light and Heavy Touch on Transtibial Amputees’ Postural Control and Weight-Bearing Asymmetry(University of Illinois Chicago, 2024) Tobaigy, Moaz; Sawers, AndrewThe objective of this thesis was to determine the effect of augmented sensory feedback and mechanical support on traumatic unilateral transtibial prosthesis users’ postural stability, neuromuscular control, and weight-bearing asymmetry during quiet stance. Our central hypothesis was that postural instability in traumatic unilateral transtibial prosthesis users is a sensory problem. To test this hypothesis 12 traumatic unilateral transtibial prosthesis users and 12 unimpaired age- and sex-matched adults were recruited, enrolled, and completed the study protocol. Participants postural stability, neuromuscular control, and weight-bearing asymmetry were assessed during quiet stance under three conditions: baseline no touch, light touch, which provides sensory feedback, and heavy touch, which provides mechanical support. Postural stability, neuromuscular control, and weight-bearing asymmetry were characterized by center of pressure mean velocity, total integrated area across select lower limb muscles, and a weight-bearing asymmetry index, respectively. In the first study of this thesis unilateral transtibial prosthesis users were found to have greater medial-lateral but not anterior-postural postural instability than age- and sex-matched adults. Importantly, this medial-lateral instability was only resolved relative to age- and sex-matched adults with mechanical support from heavy touch. In the second study we found that neither light touch (i.e., sensory) nor heavy touch (i.e., mechanical support) shifted traumatic unilateral transtibial prosthesis users’ neuromuscular control of postural stability towards proximal muscles during quiet stance. In contrast, we found that mechanical support from heavy touch significantly reduced the total muscle activity used by traumatic unilateral transtibial prosthesis users during quiet stance. In the third study of this thesis we found that despite improvements in postural stability via heavy touch, there was no accompanying reduction in weight-bearing asymmetry, suggesting that weight-bearing asymmetry is not used as a compensation to maintain stability The results of this thesis suggest that contrary to our central hypothesis postural instability in unilateral transtibial prosthesis users may be attributable to mechanical rather than sensory deficits.17 0Item Restricted Accuracy Assessment of 3D Printed Casts Using Zirconia Fixed Implant prosthesis: A Comparative Study in the Anterior Maxilla(Saudi Digital Library, 2021-06-23) Abdeen, Layal; Papaspyridakos, Panagiotis; Chen, Yo-wei; Kostagianni, Aikaterini; Finkelman, Matthew; Papathanasiou, Aikaterini; Papaspyridakos, PanagiotisObjective: The purpose of the present in-vitro study is to compare the accuracy of 3D printed casts generated from digital implant impressions with one intra-oral scanner (IOS) (Trios 3, 3Shape), from 4 3D printers, with the 3D accuracy of stone casts made by conventional implant impressions, in a partially edentulous anterior maxilla with two implants. Material and Methods: A maxillary cast with a partially edentulous anterior area was fabricated with the placement of two internal connection implants (Regular CrossFit, Straumann®, Switzerland). Stone casts (n=10) that served as a control were fabricated using the splinted open-tray impression technique. A digital impression was taken using a white light IOS (TRIOS, 3Shape), and a Standard Tessellation Language (STL) file was obtained. Four 3D printers were used to print the casts (n=10 from each 3D printer): a Straumann® P30+ (Straumann®, Switzerland) and a Varseo S (Varseo 3D printing system, BEGO®, Germany), which used digital light processing (DLP) technology; a Form 3b+ (Formlabs®, Somerville, MA, USA), which used stereolithography (SLA) technology; and an M2 Carbon (Carbon®, Redwood City, CA, USA), which used Continuous Liquid Interface Production™ (CLIP) technology. The master cast and all models generated from each group were digitized using the same IOS. Accuracy was evaluated digitally and laboratory. The obtained STL files were superimposed on the master cast STL file (reference) to evaluate the 3D accuracy digitally with inspection software (Geomagic Control X; 3D Systems) using the root mean square value (RMS). For prosthesis assessment, an implant screw-retained fixed zirconia prosthesis was fabricated and tested on each cast. Accuracy of fit was assessed using a screw resistance test and radiographic test. Results: The highest median RMS was found in the stone model group (94.6 μm) and the lowest median was in the M2 Carbon group (46.9 μm). The Kruskal-Wallis test revealed a statistically significant difference between the groups (p<0.001). For post-hoc comparisons, Dunn’s test with the Holm-Bonferroni correction resulted in a statistically significant difference in the four tests. The lowest p-value was for the comparison between the M2 Carbon and P30+ groups (p=0.002), with M2 Carbon exhibiting a significantly lower (RMS). The zirconia prosthesis fits adequately on all casts. Conclusion: Within the study’s limitations, the M2 Carbon printer in virtual analysis demonstrated statistically significant lower 3D deviations in root mean square than the Straumann® P30+ printer. Printed casts generated from M2 Carbon, Formlabs® Form 3b and BEGO® Varseo S demonstrated statistically significant lower 3D deviations in root mean square than stone models generated using a conventional implant impression for the present partially edentulous scenario with two implants. Using a screw-resistance test and radiographic assessment, the zirconia prosthesis fit was clinically acceptable on all models.20 0