Browsing by Author "Papaspyridakos, Panos"

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Accuracy of Complete Digital Workflow for Fabrication of Implant-Supported FDPs: In-vitro Study in the Anterior Maxilla
(2023-06) Altaefi, Bashayer; Papaspyridakos, Panos
Objective: To assess the accuracy of fit of implant-supported, (Polymethylmethacrylate) PMMA screw-retained prostheses fabricated using complete digital workflow. Materials and Methods: A partially edentulous maxillary 3D printed cast -Kennedy class IV- with two bone-level internal connection implants (Straumann Bone Level RC) placed at lateral incisors position (#7, #10) was used as the reference cast. A total of 50 (N=50) scans of the cast were acquired using the TRIOS scanner (TRIOS 4, 3Shape, Copenhagen, Denmark) in a controlled environment. The digital scans were exported in the Standard Tessellation Language (STL) format. The STL files were imported into CAD software (Exocad, DentalCAD version 3). Utilizing the software, a reference PMMA 4-unit implant-supported prototype prosthesis at the implant level (RC; Straumann®, Switzerland) was created. The assessment of prosthesis fit was carried out using the screw resistance test and radiographic analysis. Results: The results of the screw resistance test revealed that 98% (N=49) of the PMMA implant-supported prostheses exhibited a fit that was considered clinically acceptable. However, when assessing the fit radiographically, it was found that all 50 prototypes (100%) achieved a clinically acceptable fit. Conclusion: Within the limitations of this in vitro study, the accuracy of fit of implant-supported, PMMA screw-retained prosthesis fabricated using complete digital workflow was found to be clinically acceptable in the scenario of partially edentulous anterior maxilla.
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Prostheses Survival Rates and Technical Complications of Monolithic Zirconia Fixed Complete Arch Dental Prostheses
(Saudi Digital Library, 2023-10-08) Alireza, Badr; Papaspyridakos, Panos
ABSRACT: OBJECTIVE: The primary objective of this study was to determine the prosthesis survival and complication rates associated with monolithic zirconia implant-supported fixed full dental prostheses (IFCDPs) in completely edentulous patients after a minimum of 1-year clinical follow-up. MATERIALS AND METHODS: A convenience sample of subjects that underwent treatment with zirconia IFCDPs at the Division of Postgraduate Prosthodontics at Tufts University School of Dental Medicine (TUSDM) was used in the present retrospective study, yielding a total of 20 zirconia IFCDPs (14 participants). This study was an observational single-center retrospective clinical cohort study. Descriptive statistics were calculated. SPSS v. 28 (IBM Corp., Armonk, NY, USA) was used in the analysis. RESULTS: A study of 14 participants (28.6%) female and (71.4%) males (mean age: 67.6 years) investigated the survival and complication rates with monolithic zirconia dental prostheses. The mean duration of prosthesis use was approximately 36.8 months. The majority of the participants (85.7%) reported not using a nightguard. Bruxism was reported by 21.4% of the participants. The distribution of opposing dentition among the participants was as follows: 28.6% had natural dentition, 21.4% had implant-supported dentition, removable prosthesis, and combination of teeth and implants, and 7.1% had an implant overdenture. Out of the 20 arches, 60.0% of monolithic zirconia IFCDPs were made in the maxilla, and 40.0% in the mandible. Among the minor technical complications that were found, "Occlusal Wear" ‘Chipping’ and "Loss of Access Hole Material" emerged as the most prevalent, occurring in 25.0%,20.0%, and 20.0% of cases, respectively. In the case of the major complication "Fracture of Screw," one instance of occurrence was recorded, representing 5.0% of the cases. The mean of the number of major complications was 0.05 events. The mean number of Minor complications was slightly more common (it was 1.15 events). The mean total number of complications was 1.2 events. No prosthesis failure in this study accounted for100% survival rate of the IFCDPs. CONCLUSION: The study observed 14 individuals who received 20 monolithic zirconia implant-supported fixed complete-arch dental prostheses. Remarkably, all prostheses demonstrated a 100% survival rate, indicating no failures. The research yields valuable insights into the technical complications associated with monolithic zirconia prostheses. Nonetheless, the study's scope is limited by its small participant size and short follow-up period, potentially affecting the general applicability and long-term outcomes. To strengthen the evidence for dental prosthetic treatments, it's recommended that larger and more diverse studies with extended observation periods be undertaken.
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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,Panos
OBJECTIVE: 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.
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Three-Dimensional Accuracy of Printed Alveolar Casts
(Saudi Digital Library, 2023-08-31) Alghamdi, Mohanned; Papaspyridakos, Panos
Objective: The purpose of this in-vitro study was to evaluate the accuracy of 3D printed alveolar casts fabricated with three different 3D printers from digital scans on a reference typodont in the scenario of a maxillary veneer, two crowns, fixed dental prostheses and onlay. Material and Methods: A reference cast, prepared using a Kilgore K-2 typodont with various tooth preparations, was scanned using a Trios4 intra-oral scanner. This created an STL file that served as a digital reference for superimposition and the design of a digital alveolar cast. The digital cast was designed using (Exocad Dental CAD® 3.1 Rijeka) software, including movable dies and a cast base. This design was then exported as an STL file for 3D printing. Three 3D printers (Carbon DLS, Straumann P30+, Formlabs Form3b+) were used to print the alveolar casts, and all were cleaned and post-cured as per the manufacturers' instructions. The printed casts were then digitized using the same intra-oral scanner, and the resultant digitized casts were exported as STL files. Finally, the 3D deviations of each printed cast were calculated by superimposing the cast STL files onto the original digital reference cast using Geomagic Control X software. The software then determined the root mean square error for each clinical scenario. Results: The study observed significant differences between specific pairs of dental restorations in each category except for the veneers. For onlays, Carbon showed significantly lower RMS error compared to Formlabs® Form3b+ (P<0.001). In post-hoc comparisons, between Formlabs® Form3b+ and Straumann® P30+ (P=0.044). Similarly, Carbon exhibited significantly lower RMS error in the gold crown category than Formlabs® Form3b+ (P<0.001). For ceramic crowns, both Formlabs® Form3b+ and Carbon had significantly higher RMS error than Straumann® P30+ (P=0.004 and P=0.010, respectively). In fixed dental prostheses (FDP), Carbon had significantly less deviation than both Straumann® P30+ and Formlabs® Form3b+ (P<0.001). Notably, no significant differences were found among the veneers' RMS error values (P=0.055). Conclusion According to this study, the Continuous Liquid Interface Production (CLIP) printer exhibited higher accuracy compared to the Stereolithography (SLA) printer for onlays (P<0.001), gold crowns (P<0.001), and fixed dental prostheses (P<0.001). Also, the Continuous Liquid Interface Production (CLIP) printer exhibited higher accuracy compared to the Digital Light Processing (DLP) for fixed dental prostheses (P<0.001). On the other hand, the Digital Light Processing (DLP) exhibited higher accuracy compared to Continuous Liquid Interface Production (CLIP) the Stereolithography (SLA) printer for ceramic crowns (P=0.010), (P=0.004) respectively
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