Shedding light on rechargeable Na/Cl2 battery.

Advancing new ideas of rechargeable batteries represents an important path to meeting the ever-increasing energy storage needs. Recently, we showed rechargeable sodium/chlorine (Na/Cl2) (or lithium/chlorine Li/Cl2) batteries that used a Na (or Li) metal negative electrode, a microporous amorphous carbon nanosphere (aCNS) positive electrode, and an electrolyte containing dissolved aluminum chloride and fluoride additives in thionyl chloride [G. Zhu et al., Nature 596, 525-530 (2021) and G. Zhu et al., J. Am. Chem. Soc. 144, 22505-22513 (2022)]. The main battery redox reaction involved conversion between NaCl and Cl2 trapped in the carbon positive electrode, delivering a cyclable capacity of up to 1,200 mAh g-1 (based on positive electrode mass) at a ~3.5 V discharge voltage [G. Zhu et al., Nature 596, 525-530 (2021) and G. Zhu et al., J. Am. Chem. Soc. 144, 22505-22513 (2022)]. Here, we identified by X-ray photoelectron spectroscopy (XPS) that upon charging a Na/Cl2 battery, chlorination of carbon in the positive electrode occurred to form carbon-chlorine (C-Cl) accompanied by molecular Cl2 infiltrating the porous aCNS, consistent with Cl2 probed by mass spectrometry. Synchrotron X-ray diffraction observed the development of graphitic ordering in the initially amorphous aCNS under battery charging when the carbon matrix was oxidized/chlorinated and infiltrated with Cl2. The C-Cl, Cl2 species and graphitic ordering were reversible upon discharge, accompanied by NaCl formation. The results revealed redox conversion between NaCl and Cl2, reversible graphitic ordering/amorphourization of carbon through battery charge/discharge, and probed trapped Cl2 in porous carbon by XPS.

Group 2 ITI Consensus Report: Technological developments in implant prosthetics.

OBJECTIVES: Group-2 reviewed the scientific evidence in the field of «Technology¼. Focused research questions were: (1) additive versus subtractive manufacturing of implant restorations; (2) survival, complications, and esthetics comparing prefabricated versus customized abutments; and (3) survival of posterior implant-supported multi-unit fixed dental prostheses. MATERIALS AND METHODS: Literature was systematically screened, and 67 publications could be critically reviewed following PRISMA guidelines, resulting in three systematic reviews. Consensus statements were presented to the plenary where after modification, those were accepted. RESULTS: Additively fabricated implant restorations of zirconia and polymers were investigated for marginal/internal adaptation and mechanical properties without clear results in favor of one technology or material. Titanium base abutments for screw-retained implant single crowns compared to customized abutments did not show significant differences concerning 1-year survival. PFM, veneered and monolithic zirconia implant-supported multi-unit posterior fixed dental prostheses demonstrated similar high 3-year survival rates, whereas veneered restorations exhibited the highest annual ceramic fracture and chipping rates. CONCLUSIONS: For interim tooth-colored implant single crowns both additive and subtractive manufacturing are viable techniques. The clinical performance of additively produced restorations remains to be investigated. Implant single crowns on titanium base abutments show similar clinical performance compared to other type of abutments; however, long-term clinical data from RCTs are needed. The abutment selection should be considered already during the planning phase. Digital planning facilitates 3D visualization of the prosthetic design including abutment selection. In the posterior area, monolithic zirconia is recommended as the material of choice for multi-unit implant restorations to reduce technical complications.

Influence of different zirconia surface treatments on biofilm formation in vitro and in situ.

OBJECTIVES: To determine whether the surface treatment of zirconia affects biofilm formation in an in vitro three-species biofilm model and in situ. MATERIAL AND METHODS: Zirconia surfaces considered for the transmucosal portion of a zirconia implant were compared with polished pure titanium grade 4 (Tp). Disks 13 mm in diameter of either polished (Zp), polished and heat-treated (Zpt), machined (Zm), machined and heat-treated (Zmt) and sandblasted, etched and heat-treated (Z14) zirconia were fabricated. Surface roughness and wettability of specimens was measured. Biofilm formation was evaluated by safranin staining and scanning electron microscopy (SEM) using a three-species model, and intraorally with 16 volunteers carrying oral splints in two independent experiments. Relative biofilm formation was compared with Kruskal-Wallis followed by Bonferroni post hoc test (α = 0.05). RESULTS: In vitro biofilm formation with optical density values on Zp (0.14 ± 0.01), Zpt (0.14 ± 0.02), Zm (0.13 ± 0.01) and Zmt (0.13 ± 0.01) was significantly lower than on Tp (0.21 ± 0.05) and Z14 (0.20 ± 0.04) (p < .05). In situ biofilm formation was significantly higher on Z14 (0.56 ± 0.45) (p < .05), while no significant differences in optical density were observed among Zp (0.25 ± 0.20), Zm (0.36 ± 0.34) and Tp (0.28 ± 0.22). SEM analysis supported quantitative findings. CONCLUSIONS: In the in vitro, three-species biofilm model differences in material and surface roughness affected biofilm formation. In situ biofilm formation was mainly affected by the surface roughness of the specimens. Polishing of zirconia is recommended to reduce biofilm formation, while heat treatment has no significant effect.

Bone heating and implant removal using a high-frequency electrosurgical device: An in vivo experimental study.

OBJECTIVES: Failed implant removal using a high-frequency electrosurgical device (HFED) has been reported to be less invasive than other surgical techniques. We sought to clarify the mechanism of removal torque reduction in an implant by heating with HFED. MATERIALS AND METHODS: Sixty-eight Wistar rats received titanium implants on the maxillary bone 4 weeks after extraction of the first and second molars. The control group was sacrificed 6 weeks after implant installation. In the experimental group, the implant was heated by HFED for 10 s using three different power outputs, and samples were collected at 3, 7, and 14 days after heating. Removal torque measurement and histological analysis were performed in the control and experimental groups. Implant surfaces were observed using an electron-probe microanalyzer (EPMA). Data were analyzed using Mann-Whitney U test at a significance level of 5%. RESULTS: The removal torque could not be measured in the control group due to fracture of the implant. After heating, the removal torque was measurable without fracture and decreased significantly at 14 days as compared with that at 3 days (p < .05). Heating with "min" power output resulted in a significantly smaller blank lacunae area and fewer osteoclasts at 14 days after heating (p < .05). EPMA revealed bone matrix adherence to outer surface of heated implant. CONCLUSIONS: After heating, an enlarged area of blank lacunae around the implant and an increased number of osteoclasts into the bone marrow cavity were observed, which may have contributed to the reduction in removal torque.

Production time, effectiveness and costs of additive and subtractive computer-aided manufacturing (CAM) of implant prostheses: A systematic review.

OBJECTIVE: To systematically review the dental literature for clinical studies reporting on production time, effectiveness and/or costs of additive and subtractive computer-aided manufacturing (CAM) of implant prostheses. MATERIALS AND METHODS: A systematic electronic search for clinical studies from 1990 until June 2020 was performed using the online databases Medline, Embase and Cochrane. Time required for the computer-aided design (CAD) process, the CAM process, and the delivery of the CAD-CAM prostheses were extracted. In addition, articles reporting on the effectiveness and the costs of both manufacturing technologies were included. RESULTS: Nine clinical studies were included reporting on subtractive CAM (s-CAM; 8 studies) and additive CAM (a-CAM; 1 study). Eight studies reported on the s-CAM of prosthetic and auxiliary components for single implant crowns. One study applied a-CAM for the fabrication of an implant bar prototype. Time was provided for the CAD process of implant models (range 4.9-11.8 min), abutments (range 19.7-32.7 min) and crowns (range 11.1-37.6 min). The time for s-CAM of single implant crown components (abutment/crown) ranged between 8.2 and 25 min. Post-processing (e.g. sintering) was a time-consuming process (up to 530 min). At delivery, monolithic/veneered CAD-CAM implant crowns resulted in additional adjustments chairside (51%/93%) or labside (11%/19%). CONCLUSIONS: No scientific evidence exists on production time, effectiveness and costs of digital workflows comparing s-CAM and a-CAM. For both technologies, post-processing may substantially contribute to the production time. Considering effectiveness, monolithic CAD-CAM implant crowns may be preferred compared to veneered CAD-CAM crowns.

Cemented versus screw-retained posterior implant-supported single crowns: A 24-month randomized controlled clinical trial.

OBJECTIVES: To compare the incidence of biological and technical complications of cemented and screw-retained monolithic lithium-disilicate implant-supported posterior single crowns. MATERIAL AND METHODS: Forty-one subjects with a total of 56 implants received randomly allocated 28 cemented and 28 screw-retained crowns. In the screw-retained group, monolithic lithium-disilicate restorations were luted to titanium bases extraorally. In the cemented group, monolithic lithium-disilicate crowns were cemented on individualized titanium abutments intraorally. All restorations were examined according to modified FDI criteria within 2 weeks of inserting the crowns (baseline) and after 12 (n = 46) and 24 (n = 43) months. Bone loss was evaluated by standardized radiographs at baseline and 12 months. RESULTS: After 12 months, the incidence of mucositis (positive bleeding on probing) was 14.2% (screw-retained) and 17.9% (cement-retained). The gingival and plaque index and a mean marginal bone loss between 0.03-0.15 mm showed no significant difference between the groups. In the cemented group, cement residues were detected at baseline at two restorations (6.9%) by radiographic examination. A complete digital workflow was realized in most cases (85.7%). At 24 months, no restoration had failed, and no chipping of the ceramic had occurred. In the screw-retained group, screw loosening occurred in one implant. In both groups, there was obvious deterioration in the quality of 32% of the occlusal and of 18% of the proximal contact points. CONCLUSIONS: The type of retention mode of monolithic implant-retained lithium-disilicate posterior crowns had no influence on the biological and technical complication rate.

Applications of Bacillus subtilis Spores in Biotechnology and Advanced Materials.

The bacterium Bacillus subtilis has long been an important subject for basic studies. However, this organism has also had industrial applications due to its easy genetic manipulation, favorable culturing characteristics for large-scale fermentation, superior capacity for protein secretion, and generally recognized as safe (GRAS) status. In addition, as the metabolically dormant form of B. subtilis, its spores have attracted great interest due to their extreme resistance to many environmental stresses, which makes spores a novel platform for a variety of applications. In this review, we summarize both conventional and emerging applications of B. subtilis spores, with a focus on how their unique characteristics have led to innovative applications in many areas of technology, including generation of stable and recyclable enzymes, synthetic biology, drug delivery, and material sciences. Ultimately, this review hopes to inspire the scientific community to leverage interdisciplinary approaches using spores to address global concerns about food shortages, environmental protection, and health care.

In vitro retention force changes during cyclic dislodging of three novel attachment systems for implant overdentures with different implant angulations.

OBJECTIVES: This in vitro study aimed to compare changes in retentive force due to cyclic dislodging of three novel un-splinted attachments. MATERIALS AND METHODS: Experimental models simulating a mandibular two-implant overdenture situation, with implants positioned with various interimplant discrepancies (0°, 20°, 40°, and 60°) were fabricated. Three attachment systems were tested, "N": a straight or 15°-angulated stud; "L": a sole straight stud; and "C": a straight or individually angulated stud. All models underwent wet testing and were subjected to 10,000 insertion-removal cycles in a universal testing machine. The mean retentive forces were calculated for cycles 10, 100, 1,000, 5,000, and 10,000. Multiple mixed-effects linear regression models were applied for statistical analyses (⍺ < 0.05). RESULTS: "N" demonstrated an increasing retention until 1,000 cycles, which subsequently diminished back to its initial retention at 10,000 cycles, showing no significant loss during the entire experiment. Statistical models demonstrated no effect of implant angulation on retention, except for 60° after 10,000 cycles (p < .05). "L" showed an early peak at 100 cycles and did not significantly lose retentive force before 5,000 cycles. Angulations of 40° or higher were shown to lead to lower retentive forces (0° vs. 40° cycle 5,000: p < .05; 0° vs. 60° cycle 100: p < .05, ≥cycle 1,000: p < .001). "C" showed stable retentive forces with no significant loss only at 10,000 cycles (all angles: p < .001) or 5,000 cycles (0° vs. 60°: p < .05). CONCLUSIONS: All systems showed retentive forces promising successful clinical use in implant overdentures, even in situations with extremely angulated implants. Specific abutments compensating interimplant angulation maintain retention longer in situations with high axe divergencies.

Vertical bone augmentation with simultaneous implantation using deproteinized bovine bone block functionalized with a slow delivery of BMP-2.

OBJECTIVE: We hypothesized that a biomimetic calcium phosphate (CaP) coating which incorporates morphogenetic protein 2 (BMP-2) on the deproteinized bovine bone (DBB) blocks could be used to enhance the vertical alveolar ridge augmentation for the one-stage onlay surgery with simultaneous implants insertion. We aimed to test this hypothesis in vivo. MATERIAL AND METHODS: Beagles dogs were used for the study (n = 6 specimens per group). One month after building the edentulous animal model, 4 mm vertical alveolar bone loss were surgically created and four groups of blocks (W × L × H: 7 mm × 10 mm × 4 mm) were randomly fixed onto the reduced alveolar ridge by implants: (a) DBB blocks alone (negative control group); (b) DBB blocks with superficial adsorption of 50 µg BMP-2 (ad.BMP-2 group); (c) DBB blocks coated by biomimetic CaP coating which incorporates 50 µg BMP-2 (inc.BMP-2 group); and (d) autologous bone blocks (positive control group). After 3 months of healing, samples were harvested for micro-CT and histomorphometric analyses. RESULTS: In histomorphometry, the inc.BMP-2 group showed a significantly thicker (coronal-apically) and wider (buccal-lingually) augmented bone area, better bone-to-implant contact than the negative control group. In both the micro-CT and histomorphometry, the inc.BMP-2 group showed more mineralized tissue than the negative control group and the inc.BMP-2 group also showed significantly more newly formed bone and residual grafts than the negative control group in the upper half of the blocks. In micro-CT, the inc.BMP-2 group showed significantly more bone-to-graft contact percentage than the ad.BMP-2 group. In both micro-CT and histomorphometry, the inc.BMP-2 group showed significantly more percentage of mineralized tissue than the ad.BMP-2 group. No significant differences were found between the inc.BMP-2 group and the positive control group either in micro-CT or in histomorphometry. CONCLUSIONS: The DBB blocks with coating-delivered BMP-2 significantly enhanced the efficacy of vertical alveolar bone augmentation, compared with the unloaded blocks and blocks with adsorbed BMP-2, in the one-stage onlay surgery with simultaneous implant insertion.

A histomorphometric study on treated and untreated ceramic filled PEEK implants versus titanium implants: Preclinical in vivo study.

OBJECTIVES: To investigate the osseo-integrative behavior of untreated (UCFP) and sandblasted ceramic filled PEEK (SCFP) implants in comparison with titanium implants through measurement of bone implant contact (BIC) and bone density (BD). MATERIALS AND METHODS: Nine implants from each type were inserted into 9 dogs in which every experimental dog received the three different implants in the lower border of the mandible. The animals were euthanized after 3 months and extracting bone blocks containing implants followed by blocks preparation for histological examinations. RESULTS: BIC and BD were significantly higher in titanium and SCFP compared with UCFP group (p = .007) and (p = .012), respectively. Aluminum blasting increased the bone ingrowth and bone implant contact when compared to machined surfaces of untreated PEEK implants. CONCLUSION: In conclusion, sandblasting with 110 µm aluminum oxide particles can be proposed as a suitable surface treatment that enhances hydrophilicity of CFP. Further in vivo animal studies are still needed to confirm the findings of this study.

Phase transformation and fracture load of stock and CAD/CAM-customized zirconia abutments after 1 year of clinical function.

OBJECTIVES: Functional loading and low-temperature degradation may give rise to impaired clinical long-term service of zirconia implant abutments. The aim of this study was to compare the fracture strength (primary outcome measure) and the volume percentage of monoclinic surface zirconia (m-ZrO2 ) of stock and CAD/CAM-customized zirconia implant abutments that functioned clinically for 1 year with geometrically identical pristine controls in an ex vivo experiment. MATERIAL AND METHODS: Twenty-three stock (ZirDesign™) and 23 CAD/CAM-customized (Atlantis™) zirconia implant abutments were retrieved after 1 year of clinical service. They were compared with pristine copies with respect to the volume fraction of the monoclinic phase using Raman spectroscopy and their fracture load by means of a single load-to-fracture test. Failure analysis was performed using optical and SEM microscopy. After verification of normal distribution, paired t tests were used for comparison of fracture loads between pristine and clinically aged specimen. All statistical tests employed a level of significance of α = 0.05. RESULTS: The fracture loads of the stock zirconia abutments were significantly (p < 0.05) reduced to 78.8% (SD 29.5%) after one year of clinical function. For the CAD/CAM abutments, no reduction in fracture load was found. No m-ZrO2 volume percentages beyond the detection threshold of 5% were observed in any of the samples. CONCLUSIONS: After 1 year of clinical service, no difference in fracture strength of the CAD/CAM-customized zirconia implant abutments could be demonstrated, whereas the stock zirconia abutments decreased considerably in fracture strength. No substantial tetragonal-to-monoclinic transformation was observed.

Periodontal outcome and additional clinical quality criteria of lithium-disilicate restorations (Empress 2) after 14 years.

OBJECTIVES: To evaluate the clinical quality of tooth-supported crowns (SCs), implant-supported crowns (ISCs), and fixed dental prosthesis (FDPs) made of a lithium-disilicate glass-ceramic framework material (IPS Empress 2, Ivoclar Vivadent) after long-term use. MATERIALS AND METHODS: Between 1997 and 1999, 184 restorations (106 SCs, 32 ISCs, 33 FDPs, 13 diverse restorations) were placed in 73 patients. In 2012/2013, all patients with functioning restorations were invited to participate in a clinical follow-up examination. To investigate the clinical quality, modified California Dental Association (CDA) criteria, periodontal health, and the patient's opinion were evaluated. RESULTS: After 14 years on average, 50 restorations were available for evaluation of the CDA criteria and the patient's opinion, and 24 restorations were available for the periodontal health evaluation. Surface, color, anatomic shape, and margin integrity were considered to be in the range of excellence in 54, 78, 96, and 88%, respectively. There were no unacceptable defects. Most patients (64%) were still entirely satisfied with their restorations. Mean probing depths were significantly higher on teeth with tooth-supported Empress 2 restorations than on control teeth (p = 0.0401). No significant relationship was found between surface quality and plaque accumulation (p = 0.9450, generalized linear mixed model) or between surface quality and periodontal probing ≥ 4 mm (p = 0.4184, generalized linear mixed model). CONCLUSIONS: The clinical quality of the Empress 2 restorations that had survived 14 years on average was totally satisfactory with regard to esthetics, design, and patient's opinion. The periodontal health of all-ceramic restored teeth requires further investigation. CLINICAL SIGNIFICANCE: The practitioner's choice of dental materials is based, at best, on long-term experience. With diminishing concerns about the clinical longevity of all-ceramic restorations, the grading of clinical quality based on esthetics, design, periodontal response, and patients' opinions could, nowadays, serve as a measure for the efficiency of dental ceramic.

Then and Now-A Look Inside the Lives of 11 Women Presidents of the IADR.

Extraordinary women scientists-past, current, and elected presidents of the International Association for Dental Research (IADR)-showcase pathways for success and leadership. In this series of autobiographical essays, these women of various cultural backgrounds with diverse areas of research describe their journeys in the passionate pursuit of excellence, despite the frequent obstacles and challenges. Through interviews and in their own words, we recap highlights of their dental research journeys and inspirations, their career trajectories toward the IADR presidency, and the benefits and challenges that they faced in their careers and personal lives. The purpose of this special issue is to honor these women, their life journeys, and how they have contributed to oral health research.

Anisotropic Colloids: From Non-Templated to Patchy Templated Synthesis.

Self-assembly of colloidal particles is an important and challenging way to generate novel colloidal superstructures for new materials. Recent progress on syntheses of anisotropic colloids highlights opportunities for such self-assembly, particularly in defining new non-cubic superstructures. Both non-templated and templated synthesis play an important role in preparing anisotropic colloidal particles. In this article, we briefly summarize recent progress in anisotropic colloids by non-templated and conventional templated synthesis, and introduce a conceptual strategy of "patchy templated synthesis" that differs from the conventional approach. We illustrate this strategy with recent examples emanating from colloidal rings, and discuss the future opportunities with this strategy for the synthesis of other anisotropic colloids.

Original vs. non-original abutments for screw-retained single implant crowns: An in vitro evaluation of internal fit, mechanical behaviour and screw loosening.

OBJECTIVES: To assess the internal accuracy, mechanical behaviour under static load and screw loosening before and after cyclic loading of implant-supported crowns restored with original components or with two compatible non-original brands. MATERIALS AND METHODS: Sixty-three dental implants were divided into three groups (n = 21 each): Group 1 used original components, and groups 2 and 3 used non-original components. Internal accuracy was measured throughout a cross section of the sample groups (n = 8) using scanning electron microscopy (SEM) to evaluate the fit for implant-abutments, implant-crowns and crown-abutments. To evaluate load-bearing capacity, eight samples from each group were loaded until fracture according to ISO Norm 14801. The removal torque value (RTV) was evaluated in the screws connecting the crown with the abutment and the abutment with the implant before and after cyclic loading (2 x 106 cycles) in five samples from each group. The data were analysed using the Kruskal-Wallis test (p < 0.05). RESULTS: Statistically significant differences were found among the mean crown-abutment gaps measured in Group 1 (9.3 µm), Group 2 (45.4 µm) and Group 3 (44.9 µm). Higher values for mean load-bearing capacity were found in Group 1 (1,098 N) than in groups 2 and 3 (1,057 and 973 N, respectively); however, these differences were not statistically significant. Original abutment-implant screws exhibited lower percentages of torque reduction than the non-originals. CONCLUSIONS: Enhanced fit is expected when original components are used. The original abutments exhibited lower percentages of torque reduction after cyclic loading than non-originals.

Implant-associated gene expression in the jaw bone of smokers and nonsmokers: A human study using quantitative qPCR.

OBJECTIVES: This study aimed to compare the molecular events in implant-adherent cells and in peri-implant bone during the osseointegration of machined and oxidized titanium implants in smokers and nonsmokers. MATERIALS AND METHODS: Twenty-four smokers and 24 nonsmokers each received machined and anodically oxidized mini-implants. The mini-implants and the surrounding bone were retrieved after 1, 7, and 28 days, for gene expression analysis of selected factors using quantitative polymerase chain reaction (qPCR). RESULTS: Differences between machined and oxidized implants were more evident in the implant-adherent cells than the peri-implant bone. The machined implants revealed higher expression of proinflammatory cytokines, interleukin-8 (IL-8) (in nonsmokers), and tumor necrosis factor-alpha (in nonsmokers and smokers), compared with the oxidized implants. Conversely, the expression of bone formation genes, alkaline phosphatase and osteocalcin, was generally higher at the oxidized implants. In smokers, the temporal pattern revealed the delayed and initial inhibition of osteoblastic and osteoclastic gene expression, respectively, mainly at the machined implants. In contrast, oxidized implants revealed higher expression of bone remodeling, cathepsin K (CatK) and calcitonin receptor, and coupling, receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin, genes after 7 day in smokers. CONCLUSIONS: The implant-adherent cells are more sensitive to surface properties and smoking conditions than the cells in the peri-implant bone. Smoking imposes inhibitory effects on the initial molecular events of osseointegration in the human bone-implant interface. The surface properties of oxidized implants appear to have a beneficial effect on osseointegration by mitigating the smoking-induced negative effects.

Ten-year survival and chipping rates and clinical quality grading of zirconia-based fixed dental prostheses.

OBJECTIVES: To prospectively evaluate the clinical long-term outcome of 3- to 6-unit fixed dental prostheses (FDPs) made of hot isostatic pressed (HIP) zirconia frameworks, veneered with a synthetic sintering glass-ceramic. MATERIALS AND METHODS: A total of 27 different restorations were cemented in 21 patients. FDPs were examined with regard to biological and technical complications/failures. Additionally, clinical quality was assessed based on (i) the California Dental Association (CDA) criteria, (ii) the patient's viewpoint according to Hickel, and (iii) periodontal parameters. Descriptive statistics were computed. The Kaplan-Meier estimator was used for the survival and chipping-free rates. Wilcoxon signed ranks test (ordinal/continuous data) or the McNemar test (binary data) was used to describe the periodontal outcome of abutment teeth versus that of the respective control teeth. RESULTS: After a mean observation period of 10.0 ± 2.1 years, the dataset comprised 15 patients with 20 (mainly posterior) FDPs. The 10-year survival rate and 10-year chipping-free rate were 95.0% (CI 86.0-100%) and 78.8% (CI 62.2-99.7%), respectively. Evaluation based on the CDA criteria yielded satisfactory (excellent or acceptable) results for all categories. This was also confirmed by the high level of patient satisfaction. The periodontal health of tissues adjacent to the study teeth was clinically acceptable, but inferior to the ones of control teeth. CONCLUSIONS: FDPs made from CAD/CAM-fabricated HIP zirconia ceramic frameworks have a favorable survival rate. However, because damage to the surface texture showed a disproportionate increase after long-term usage, additional long-term studies are required. CLINICAL RELEVANCE: The outstanding mechanical properties of zirconia-based systems have contributed to the belief that all-ceramics are a reliable material for prosthetic restorations. However, only long-term reports (such as this one) provide more detailed information on actual clinical efficacy.

Computer-assisted template-guided custom-designed 3D-printed implant placement with custom-designed 3D-printed surgical tooling: an in-vitro proof of a novel concept.

OBJECTIVES: The aim of this study was to introduce a new concept for computer-assisted template-guided placement of a custom 3D-designed/3D-printed implant with congruent custom 3D-designed/3D-printed surgical tooling and to test the feasibility and accuracy of this method in-vitro. MATERIALS AND METHODS: One partially edentulous human mandibular cadaver was scanned with a cone-beam computed tomography (CBCT) system and intra-oral scan system. The 3D data of this cadaver were imported in specialized software and used to analyse the region of a missing tooth. Based on the functional and anatomical parameters, an individual implant with congruent surgical tooling and surgical guided template was designed and 3D-printed. The guided osteotomy was performed, and the custom implant inserted. To evaluate the planned implant position in comparison with the placed implant position, the mandible with implant was scanned again with the CBCT system and software matching was applied to measure the accuracy of the procedure. RESULTS: The angular deflection with the planned implant position was 0.40°. When comparing the 3D positions of the shoulder, there is a deviation of 0.72 mm resulting in an apical deviation of 0.72 mm. CONCLUSION: With the use of currently available technology, it is very well feasible to create in a virtual simulation a custom implant with congruent custom surgical tooling and to transfer this to a clinical setting. However, further research on multiple levels is needed to explore this novel approach.

Retention of implant-supported overdentures at different implant angulations: comparing Locator and ball attachments.

OBJECTIVES: To assess the effect of implant angulation on the retention of two different attachment systems for implant-supported overdentures after a simulated fatigue period of 5.5 years. MATERIAL AND METHODS: Two test set-ups were constructed. A two-implant mandibular implant-supported overdenture design was simulated using acrylic resin blocks to support implant replicas (Model 1 and Model 2). The replicas were set up in the canine regions (22-mm inter-implant distance). In Model 1, the implants were parallel (0° to the vertical axis) and in Model 2 they were divergent (20° to the vertical axis). The Locator and the ball attachment systems were tested at both set-ups. A simulated fatigue period of 5.5 years that equated to 10,000 cycles of insertion and removal of the denture was used. Retention values for each attachment system at each angulation set-up were measured at baseline, every 500 cycles until 4000 cycles and then every 1000 cycles. RESULTS: After simulated fatigue, the retention for both systems at both set-ups reduced. The Locator system reduced from 108.9 to 20.2 N in the parallel set-up and from 82.3 to 17.3 N in the divergent set-up. For the ball system, the retention reduced from 56.2 to 46 N when parallel and from 45.7 to 40.7 N when divergent. CONCLUSION: Both attachment systems showed a significant reduction in retention after simulated fatigue at both parallel and divergent set-ups. The change in implant angulation caused a significant reduction in retention for the ball attachment system only, although this was still higher at the end of testing than the Locator attachment system. The Locators also had a significantly faster rate of loss of retention at both set-ups. Clinically, this may indicate that the ball attachments may perform better with divergent implants.

Micromorphological differences of the implant-abutment junction and in vitro load testing for three different titanium abutments on Straumann tissue level implants.

BACKGROUND: The aim of this study was to investigate the micromorphological differences among three commercially available titanium abutments on Straumann implants. Furthermore, the possible impact of functional loading on the micromorphology and potential complications was investigated with the use of in vitro testing. MATERIAL AND METHODS: Three groups of Titanium abutments (A: Straumann Variobase n = 5, B: EBI best Duo n = 5, and C: Implant Direct n = 5) were torqued on Straumann RN implants, as according to each of the manufacturer's instructions. The implant-abutment units were scanned with Micro-CT. Three units of each group were directly sliced in the microtome and photographed under different magnifications (10×-500×) through a Scanning Electron Microscope. Six units (two from each group) were restored with cement-retained crowns, subjected to 2000,000 load cycles with loads between 30 and 300 N at 2 Hz, examined through Micro-CT and finally sliced and photographed as described above. The micromorphology of each unit was studied, and the total length of tight contact (<3 µm) was calculated between the implant, abutment and screw contact areas. RESULTS: Major morphological differences were identified between the three units, as well as differences in the extent of tight contact in all areas examined. Despite the morphological differences, the 2M cycles of loading via in vitro test did not result in any noticeable complications although some changes in the micromorphology were observed. CONCLUSION: The examined implant-abutment units presented with major morphological differences. Two million cycles of in vitro loading did not appear to affect the stability of the units despite the micromorphological changes. These results need to be interpreted however under the limitations of the small sample size and the specific set-up of the in vitro testing.