Influence of Kennedy class and number of implants on the accuracy of dynamic implant navigation: An in vitro study using an X-ray free evaluation methodology.

OBJECTIVES: The aim of this in vitro study was to evaluate the accuracy of fully guided dynamic implant navigation surgery in Kennedy I, II, and III class dental arch defects with two different implant designs, using an X-ray free evaluation method. METHODS: Polyurethane resin maxillary models simulated posterior edentulous defects. Four cone beam computed tomography (CBCT) scans and four intraoral (IOS) scans were obtained for each model and a digital wax-up with the correct implant positions was made. The accuracy of implant positions was evaluated using an IOS-based X-ray-free method (3Shape). Four deviation characteristics were evaluated: insertion point, depth deviation, horizontal and angle deviation. RESULTS: The insertion point deviation measures ranged from 0.19 mm to 1.71 mm. Depth (s) and (u) deviations ranged from -1.47 mm to 0.74 mm and from 0.02 mm to 1.47 mm, respectively. Horizontal deviation ranged from 0.09 mm to 1.37 mm. CONCLUSIONS: There is a tendency of a decreasing insertion point deviation for an increasing number and distribution area of the teeth (increasing Kennedy class number). Kennedy class II and distal implant position had the most influence for the higher deviations. CLINICAL SIGNIFICANCE: Dynamic implant guidance provides accurate spacing, angulation, depth and position of the implants. It is important to understand how the number of missing teeth and implant design could influence the accuracy of dynamic implant navigation. Thus, it is important to evaluate factors influencing the accuracy of dynamic systems by using a X-ray-free post-operative method and to overcome the limitations of providing multiple CBCT scans.

The Effect of UV Treatment on Surface Contact Angle, Fibroblast Cytotoxicity, and Proliferation with Two Types of Zirconia-Based Ceramics.

UV photofunctionalization of Zirconia-based materials for abutment fabrication is a promising approach that might influence the formation of a sound peri-implant seal, thus promoting long-term soft and hard tissue implant integration. This study aimed to evaluate the effect of UV treatment of test specimens made by two different ZnO2-based ceramic materials on the hydrophilicity, cell cytotoxicity, and proliferation of human gingival fibroblasts (HGFs). Two Zirconia-based materials, high-translucent and ultra-translucent multi-layered Zirconia (Katana, Kuraray Noritake, Japan), were used to prepare a total of 40 specimens distributed in two equally sized groups based on the material (n = 20). The same surface finishing protocol was applied for all specimens, as suggested by the manufacturer. Half the specimens from each group were treated with UV-C light for 48 h. Water contact angle (WCA), fibroblast cytotoxicity, and proliferation were investigated. The WCA values for the high-translucent Zirconia ranged from 69.9° ± 6.4° to 73.7° ± 13.9° for the treated/non-treated specimens and from 79.5° ± 12.8° to 83.4° ± 11.4° for the ultra-translucent multi-layered Zirconia, respectively. However, the difference was insignificant (F(16) = 3.50, p = 0.292). No significant difference was observed for the fibroblast cytotoxicity test. The results for proliferation revealed a significant difference, which was material-dependent (F(8) = 9.58, p = 0.005). We found that UV surface photofunctionalization of ZrO2-based materials alters the human gingival fibroblast cell viability, which might produce favourable results for cell proliferation.

Model-free digital workflow and immediate functional loading of implant-supported monolithic glass-ceramic crowns: A case series.

OBJECTIVES: The aim of this study was to evaluate surgical and prosthetic outcomes of immediate functional loading of implants with glass-ceramic screw-retained single crowns. METHODS: A total of 22 implants were placed. Within 24 h, functional full-contour glass ceramic crowns were delivered to patients. The amount of attached gingiva, Simplified Oral Hygiene Index Score, bleeding on probing, time after extraction, bone type, implant size, soft tissue thickness, primary stability, a general fit of the restoration, occlusal and proximal contacts were recorded. Restorations were followed-up at 1, 3, and 6 months tracking marginal bone loss (MBL), noting changes in occlusal and interproximal contacts, checking other possible complications. RESULTS: One implant failed and was removed after 4 weeks (95.5% survival rate). The rest of the implants and crowns functioned with no complications during the follow-up period of 6 months. Factors such as time after extraction, bone type, implant size, soft tissue thickness, and primary stability recorded in Ncm and implant stability quotient (ISQ) values, were not associated with MBL (p<0.05). Mean MBL was found to be 0.3 mm (standard deviation = 0.42) mesially and 0.4 mm (standard deviation = 0.66) distally. One distal and one mesial proximal contact were found to be missing at the 6-month check-up appointment. CONCLUSIONS: Within the limits of this study, fully digital workflow without a 3D printed model could be successfully employed for immediate functional loading with single-unit implant-supported crowns. Further studies are needed to obtain long-term results with a larger sample of patients. CLINICAL SIGNIFICANCE: Model-free digital workflow and immediate functional loading of implant-supported monolithic glass-ceramic crown might be viable option to restore a single tooth defect.

The Effect of Different Cleaning Protocols of Polymer-Based Prosthetic Materials on the Behavior of Human Gingival Fibroblasts.

Dental implant abutment and prosthetic materials, their surface treatment, and cleaning modalities are important factors for the formation of a peri-implant soft tissue seal and long-term stability of bone around the implant. This study aimed to investigate the influence of a polymeric material surface cleaning method on the surface roughness, water contact angle, and human gingival fibroblasts (HGF) proliferation. Polymeric materials tested: two types of milled polymethylmethacrylate (PMMA-Ker and PMMA-Bre), three-dimensionally (3D) printed polymethylmethacrylate (PMMA-3D), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Titanium (Ti) and zirconia oxide ceramics (ZrO-HT) were used as positive controls. A conventional surface cleaning protocol (CCP) was compared to a multi-step research cleaning method (RCP). Application of the RCP method allowed to reduce Sa values in all groups from 0.14-0.28 µm to 0.08-0.17 µm (p < 0.05 in PMMA-Ker and PEEK groups). Moreover, the water contact angle increased in all groups from 74-91° to 83-101° (p < 0.05 in the PEKK group), except ZrO-HT-it was reduced from 98.7 ± 4.5° to 69.9 ± 6.4° (p < 0.05). CCP resulted in higher variability of HGF viability after 48 and 72 h. RCP application led to higher HGF viability in PMMA-3D and PEKK groups after 48 h, but lower for the PMMA-Ker group (p < 0.05). After 72 h, no significant differences in HGF viability between both cleaning methods were observed. It can be concluded that the cleaning method of the polymeric materials affected surface roughness, contact angle, and HGF viability at 48 h.