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Purpose: To investigate the esthetic outcomes based on the color differences in zirconia (Zr) of varying thickness, resin cement color, and types of titanium (Ti) implant surface treatments. Materials and Methods: Overall, 28 high-translucency monolithic zirconia (HTMZ) specimens were arranged into four groups based on Zr thickness: 1.0, 1.5, 2.0, and 2.5 mm (n = 7 per thickness). Each group was tested using two resin cement colors (clear and opaque) in combination with six surface-treated Ti groups (n = 7), including untreated titanium (UT), anodization (AN), 50-µm alumina airborne-particle abrasion followed by AN (SBAN), AN followed by 50-µm alumina airborne-particle abrasion (ANSB), 9.5% hydrofluoric acid followed by AN (HFAN), and AN followed by 9.5% hydrofluoric acid (ANHF). This created a total of 48 experimental groups, including the use of composite resin (n = 7, shade A2D) for four control groups. All specimens were measured using a spectrophotometer and subsequently compared with composite resin (control) with the corresponding Zr thickness to establish color differences. A color difference of < 2.7 was considered clinically acceptable. The data obtained were statistically analyzed using ANOVA and post hoc test (P = .05). Results: Zr thickness, resin cement color, and type of Ti implant surface treatment significantly affected the observed color differences (P < .05). When using 2.5-mm HTMZ with clear resin cement on AN, UT, SBAN, HFAN, and ANSB, the mean color differences were below the clinically acceptable values, and the 95% CIs of color differences were below the clinically acceptable values for AN, UT, and SBAN groups. Conclusions: HTMZ with a minimum thickness of 2.5 mm and clear resin cement on AN, UT, and SBAN groups potentially result in acceptable color matching with 95% CIs. [ABSTRACT FROM AUTHOR]

This study compared the survival, marginal bone loss (MBL), and prosthetic complications of 4.5-mm extra-short implants and longer implants splinted to the short implants via the restoration. A retrospective controlled cohort study was performed. The 4.5-mm extra-short group (study group; SG) included 48 consecutively placed implants. The control group (CG) included 48 implants splinted to the extra-short implants. The same surgical team treated the 39 included patients, and all implants were restored with a screw-retained fixed restoration and intermediate abutments. Immediate and conventionally loaded implants were included. All implants were in function during the follow-up period (14 ± 3.4 and 17 ± 13 months for SG and CG, respectively). No differences in technical complications were observed between the groups (one and two cases of screw loosening for SG and CG, respectively; two provisional prosthesis fractures for SG; P = .310). Marginal bone stability was similar for SG and CG at the mesial level (-0.01 ± 0.28 mm for SG vs -0.18 ± 0.72 mm for CG; P = .270) and at the distal level (0.02 ± 0.39 mm for SG vs -0.18 ± 0.68 mm for CG; P = .076). The same good clinical performance could be observed for 4.5-mm implants and longer implants under the same prosthesis. [ABSTRACT FROM AUTHOR]

Purpose: To develop the most compatible cementation protocol for ensuring minimal residual cement and optimal retention of cement-retained implant-supported fixed dental prostheses. Materials and Methods: A total of 30 custom implant abutments and zirconia crowns with bilateral wings were prepared. Three cement types were used for cementation: noneugenol resin cement (Premier Implant Cement; Group IC), dual-polymerizing self-adhesive resin cement (SmartCem2; Group SC), and zinc oxide eugenol cement (Temp-Bond; Group TB; n = 30 per group). Three cementation methods were applied for each cement type, and the samples were divided into subgroups: (1) cement was injected using a graduated syringe (ICN, SC-N, and TB-N); (2) a cementation jig made with a silicone impression material and temporary resin material was used (IC-CJ, SC-CJ, and TB-CJ); (3) 3D-printed abutments were used as replicas for cementation (IC-3DP, SC-3DP, and TB-3DP). The amount of cement injected, surface area of the residual cement, and retentive strength were measured. Kruskal-Wallis and post-hoc Mann-Whitney tests were used for statistical analyses. Results: Excess cement was not observed when cementation jig or 3D-printed replicas were used. For IC and SC subgroups, non-use of these auxiliary tools resulted in significantly higher amounts of injected cement. The retentive strength differed significantly among the IC subgroups but not among the SC subgroups. The retentive strength of subgroups TB-N and TB-CJ was significantly higher than that of subgroup TB-3DP. Conclusions: To prolong the main purpose of each cement type, a cementation jig or 3D-printed replica is highly recommended regardless of the cement type. [ABSTRACT FROM AUTHOR]

Surface contaminants on customized implant abutments could trigger an inflammatory response in the peri-implant tissues. The aim of this randomized controlled study was to assess the radiographic bone changes around implants restored with customized, platform-switched abutments, with and without autoclave treatment, 12 months after definitive restoration. Dental implants were placed 1 mm subcrestally in 64 systemically healthy patients (mean age: 63.3 ± 10.0 years; 31 patients had a history of periodontitis) to replace single or multiple missing teeth. According to a randomization list, abutments were subjected to steam and autoclave sterilization (43 implants, test group) or steam cleaning alone (44 implants, control group). Periapical standardized radiographs were taken at implant placement, prosthetic abutment connection, and 12 months after definitive cement-retained restoration. All implants were clinically stable without any sign of infection at the 12-month follow-up. An average marginal bone loss of 0.25 ± 0.19 mm was found in the test group compared to 0.35 ± 0.23 mm in the control group (no statistically significant difference), while the percentage of bleeding sites was significantly higher in the control group (8.7% ± 13.1% vs 19.1% ± 19.8%; P = .035). Autoclave treatment of customized abutments seems to reduce the inflammatory response around subcrestally placed implants. [ABSTRACT FROM AUTHOR]

Following implant placement, a soft tissue barrier will form at the healing abutment connection called peri-implant mucosa. The dimension of this anatomical structure seems to play a key role in maintaining long-term peri-implant and marginal bone level stability. In its early stages, soft tissue healing is a process involving many cellular and molecular events. Enamel matrix derivative (EMD) may improve and accelerate soft tissue wound healing and inflammatory resolution. In the present split-mouth randomized clinical trial, EMD was used to influence the early phase of soft tissue healing around dental implants placed with a single-stage approach into a completely healed ridge. A total of 60 implants were placed in 30 patients (2 implants per patient, one in the test group and one in the control group). In the test sites, EMD was administered around the healing abutment before soft tissues were sutured. Soft tissue healing index (HI) and secondary endpoints (clinical, radiographic, and patientreported outcomes) were measured. Better outcomes were recorded in patients receiving EMD for all parameters. The present results support the use of EMD to improve and accelerate soft tissue wound healing around implants. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effect of taper, length, angle, and number of vertical axial walls on the retentive strength of a cemented crown on a partially customized hybrid abutment in the esthetic zone. Materials and Methods: A total of 35 metal copings were used and divided into two groups. One group had 30 copings cemented to their corresponding 8-degree tapered abutment with lengths from 3 to 8 mm, increasing in 1-mm increments (5 copings per length). The other group had the remaining 5 copings and consisted of a standardized metal coping that matched a hexagonal abutment with 3-mm vertical axial walls and the sequential removal of 1, 2, and 3 contiguous vertical axial walls. Dislodgment tests were performed for all copings in both groups. Maximum retentive forces were measured in retentive strength (kgF), with a conversion factor of 9.807 N = 1 kgF. Results: At each tapered abutment length, the retentive strength increased proportionally and was significantly different, ranging from 31.67 ± 4.10 kgF to 67.68 ± 11.22 kgF (F [5,24] = 20.46, P < .001). An unmodified hexagonal abutment demonstrated the highest retentive strength (70.15 ± 12.97 kgF). The sequential removal of 1, 2, and 3 contiguous vertical axial walls of the hexagonal abutment resulted in retentive strength values of 59.89 ± 10.06 kgF, 57.01 ± 9.62 kgF, and 55.99 ± 9.35 kgF, respectively, with no significant difference (P > .05) in strength. Conclusions: A partially customized abutment with vertical axial walls on one side and a profile reduction on the opposite side can provide comparable retention to cemented copings at one-third the length and at one-sixth the surface area of an 8-mm abutment with an 8-degree taper. [ABSTRACT FROM AUTHOR]

Purpose: To assess the survival of double-crown-retained implant-and-tooth-supported removable partial dentures (DCR-ITSRPDs), evaluate abutment survival, and identify first aftercare measures. Materials and Methods: The influence of various factors on the survival of the DCR-ITSRPDs and the abutments were observed in this retrospective and clinical follow-up study using the Kaplan-Meier estimate. In addition, the first-required aftercare measure for each prosthesis was evaluated. Results: In total, 47 DCR-ITSRPDs were investigated (mean observation: 4.3 ± 3.8 years; max: 14.3 years), 3 of which (6.4%) had to be replaced. The survival probability for DCR-ITSRPDs was 100% at 5 years and 75% at 10 years. A total of 297 abutments (120 natural teeth and 177 dental implants) were observed, 22 of which (7.4%; 6 teeth and 16 implants) failed. The survival probability for teeth was 90.2% at the 5- and 10-year mark; for dental implants, it was 90.4% at 5 years and 76.3% at 10 years. Conclusions: DCR-ITSRPDs are a successful and durable treatment option for patients with substantially reduced residual dentitions. Both prostheses and abutments show good survival times after 5 and 10 years in function. The patient-associated factors tested showed no influence on the survival of DCR-ITSRPDs and abutments. Peri-implant infection was the decisive factor for abutment loss; therefore, regular dental prophylaxis and examinations are of major importance. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the screw loosening and fracture resistance of different hybrid abutment crown restorations after thermomechanical aging. Materials and Methods: Restorations were produced from zirconia, lithium disilicate, and hybrid ceramics with a CAD/CAM system (n = 10). Restorations and titanium bases (Ti-bases) were cemented, and the abutment screws were torqued to 30 Ncm. They were retorqued after 10 minutes, and then the removal torque values (RTVs) were measured. After 250,000 and 500,000 cycles of thermomechanical aging were completed, the RTVs were measured again, and removal torque loss (RTL) ratios were calculated. The specimens were subjected to a fracture resistance test after 750,000 cycles of thermomechanical aging, and the load at failure was recorded as the fracture resistance (N). The results were statistically analyzed (a = .05). Results: Aging was effective on the RTVs and RTL ratios (P < .001). The highest RTV was observed before aging; however, the RTVs significantly decreased and RTL ratios significantly increased after aging (P < .05). The fracture resistance values significantly differed among the ceramic materials. All lithium disilicate and hybrid ceramic specimens showed restoration fracture and most of the zirconia specimens showed Ti-base-related failure. Conclusions: Hybrid abutment crowns made of zirconia, lithium disilicate, and hybrid ceramics can withstand the average occlusal forces in the molar region; however, the ceramic type may affect the failure type. Retightening of the abutment screws after 10 minutes following the first tightening and annually may be beneficial to prevent the adverse effects of screw loosening on the integrity of the implant-abutment connection. [ABSTRACT FROM AUTHOR]

Purpose: To examine the behavior and function of human gingival fibroblasts growing on healing abutments with or without laser-textured topography. Materials and Methods: Human primary gingival connective tissue fibroblasts were cultured on healing abutments with machined or laser-textured (Laser-Lok, BioHorizons) surfaces. Cellular and molecular responses were evaluated by a variety of tests, including cell density assay (WST-1), fluorescence microscopy, real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and detachment tests. Results: The machined surface showed monodirectional traces and scratches from milling, whereas the laser-textured surface showed a distinct morphology consisting of monodirectional mesoscale channels (15-µm pitch) and woven oblique microridges formed within the channels. There were no differences in initial fibroblast attachment, subsequent fibroblast proliferation, or collagen production between the machined and laser-textured surfaces. Fibroblasts growing on a laser-textured surface were found to spread in one direction along the mesochannels, while cells growing on machined surfaces tended to spread randomly. Fibroblasts on laser-textured surfaces were 1.8 times more resistant to detachment than those on machined surfaces. An adhesive glycoprotein (fibronectin) and transmembrane adhesion linker gene (integrin ß-1) were upregulated on laser-textured surfaces. Conclusions: The increased fibroblast retention, uniform growth, and increased transcription of cell adhesion proteins compellingly explain the enhanced tissue-level response to laser-created and hybrid-textured titanium surfaces. These results provide a cellular and molecular rationale for the tissue reaction to this unique surface; in addition, they support its extended use, from implants and healing abutments to diverse prosthetic components where enhanced soft tissue responses would be desirable. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate four decontamination strategies utilizing enzymatic agents available in most clinical settings to determine (1) the amount of biomaterial that can be removed in a group of previously used healing abutments (uHAs) and (2) the degree to which the decontaminated HAs are capable of inducing an inflammatory response in vitro compared to new HAs. Materials and Methods: In total, 50 HAs were collected following 2 to 4 weeks of intraoral use and distributed randomly into five test groups (groups A-E; n = 10 per group). Group A used enzymatic cleaner foam and an autoclave. Group B used an ultrasonic bath with enzymatic cleaner and an autoclave. Group C used a prophy jet, enzymatic cleaner foam, and an autoclave. Group D used a prophy jet, an ultrasonic bath with enzymatic cleaner, and an autoclave. Lastly, group E used a prophy jet and an autoclave. The control group consisted of 10 new and sterile HAs. Residual protein concentration was determined by a Micro BCA protein assay (Thermo Fisher Scientific), while HAs from each group were stained with Phloxine B and macroscopically examined for the presence of debris. To examine the inflammatory potential, human primary macrophages were exposed to HAs, and supernatant levels of nine cytokine and chemokine profiles were analyzed using a multiplex bead assay. Results: All test groups showed differences in the degree of visual decontamination compared to controls. Groups D and E displayed the most effective surface debris removal and reduced protein concentration, while group A was the least effective. However, compared to controls, all test groups showed high levels of inflammatory cytokine secretion via multiplex assay for up to 5 days. Conclusions: Our study found that decontamination of uHAs utilizing enzymatic cleaners failed to reestablish inert HA surfaces and prevent an inflammatory immune response in vitro. Clinicians should not reuse HAs even after attempts to decontaminate and sterilize HA surfaces. [ABSTRACT FROM AUTHOR]

Purpose: To assess the clinical concept of patient treatment with fixed tooth- and implant-supported restorations in a university-based undergraduate program after 13 to 15 years. Materials and Methods: In total, 30 patients (mean age 56 years) who had received multiple tooth- and implant-supported restorations were recalled after 13 to 15 years. The clinical assessment comprised biologic and technical parameters as well as patient satisfaction. Data were analyzed descriptively, and the 13- to 15-year survival rates for tooth- and implant-supported single crowns and fixed dental prostheses (FDPs) were calculated. Results: The survival rate of tooth-supported restorations amounted to 88.3% (single crowns) and 69.6% (FDPs); in implants, it reached 100% for all types of restorations. Overall, 92.4% of all restorations were free of technical complications. The most common technical complication was chipping of the veneering ceramic (tooth-supported restorations: 5.5%; implant-supported restorations: 13% to 15.9%) regardless of the material used. For tooth-supported restorations, increased probing depth = 5 mm was the most frequent biologic complication (22.8%), followed by endodontic complications of root canal-treated teeth (14%) and loss of vitality at abutment teeth (8.2%). Peri-implantitis was diagnosed in 10.2% of implants. Conclusions: The results of this study indicate that the clinical concept implemented in the undergraduate program and performed by undergraduate students works well. The clinical outcomes are similar to those reported in the literature. In general, the majority of biologic complications occur in reconstructed teeth, whereas implant-supported restorations are more prone to technical complications. [ABSTRACT FROM AUTHOR]

In our previous test model, the abutment teeth and the model base were printed with resin and bonded with a polyether material. Some abutment teeth were fractured during the mechanical load test. Therefore, the aim was to develop and evaluate a new model under mechanical loading until fracture with zirconia FPD frameworks. At a fracture load of up to 1,636 N, neither the artificial abutment teeth nor the base model fractured. Furthermore, the artificial abutment teeth did not detach from the base model. Therefore, the model should be suitable for mechanical testing of most ceramic-based framework materials for three-unit FPDs. [ABSTRACT FROM AUTHOR]

This document is a scientific study that examines the contamination levels on dental abutments and the effectiveness of a cleaning protocol. The study finds that custom-made abutments have surface pollutants, and laboratory procedures increase the amount of pollutants. However, the cleaning protocol tested is highly effective in cleaning both titanium and zirconia abutments. The study suggests that decontaminating abutments before placement may improve tissue integration. [Extracted from the article]

Purpose: The aims of the study were to evaluate the clinical performance and the complications of combined tooth-/implant-supported three-unit fixed partial dentures (FPDs) in the posterior mandible. Materials and Methods: A total of 78 partially edentulous patients in the posterior mandible were recruited for the study (n = 26/group). Group 1 served as the control group and received two dental implants to support a three-unit FPD. Groups 2 and 3 were the experimental groups in which one implant was placed in conjunction with support from an adjacent tooth to support a three-unit FPD. Standard implants (= 8 mm) were included in Group 2, while short implants (< 8 mm) were included in Group 3. Periapical radiographs were taken for evaluation of crestal bone loss (CBL). Modified plaque index (MPI), bleeding index (BI), and sulcus depth values of the abutment teeth were recorded at the time of FPD delivery, 6 months after FPD delivery, and annually thereafter. Recorded complications included abutment tooth intrusions, cementation failures of the restorations, porcelain chipping/delamination, framework fracture, abutment screw loosening, abutment and abutment screw fracture, and implant fracture. Results: Statistically significant differences were observed between Group 1 (0.06 ± 0.17) and Group 2 (0.18 ± 0.32) and between Group 1 and Group 3 (0.17 ± 0.30) in terms of MPI (P = .05). No difference was observed between Group 2 (0.11 ± 0.34) and Group 3 (0.14 ± 0.36) or between Group 1 (0.04 ± 0.22) and Group 2 in terms of BI. There were statistically significant differences in terms of CBL between Group 1 (0.259 ± 0.05 mm) and Group 3 (0.11 ± 0.03 mm) and between Group 2 (0.03 ± 0.03 mm) and Group 3 (P = .05). The mean abutment tooth sulcus depth was 1.11 ± 0.31 mm for Group 2 and 1.20 ± 0.46 mm for Group 3. Conclusions: Within the limitations of the current study, it was concluded that combined tooth/implant-supported prostheses (CTISPs) are a predictable treatment choice in the posterior mandible. When a CTISP is planned, it is more predictable to use a short implant than a standard-length implant. [ABSTRACT FROM AUTHOR]

Purpose: This prospective study evaluated the marginal bone level and periodontal parameters 6 years after placement of a convergent transmucosal neck implant. Materials and Methods: In total, 71 implants were placed in 60 patients. Of these, 52 implants were placed with a flapless technique and with the convergent neck exposed by 1 mm (early and delayed placement), while 19 implants were placed immediately after extraction (immediate placement). At least 3 months after insertion, customized abutments were applied and provisional resin crowns were cemented, while being careful to prevent any tissue compression. After 3 weeks, definitive metal-ceramic crowns were designed with the finish line at the soft tissue level and free from any compression. The implant survival rate at 6 years, marginal bone level changes (ΔMBL, mm), and Pink Esthetic Score (PES) were evaluated. Gingival phenotype was determined before the implant surgeries (thin/thick). A three-level hierarchical model was examined with a random intercept and random slope on follow-up time at the patient level and a random intercept at the implant level. Results: In all, 57 patients with 67 implants reached the 6-year point; 3 patients (5.0%) dropped out. The implant survival rate was 100%. ΔMBL from baseline to 24 months was 0.58 mm (95% CI: 0.48, 0.68), while ΔMBL from 24 to 72 months was 0.33 mm (95% CI: 0.19, 0.47). PES improved steadily from 6 to 48 months (+0.96; 95% CI: 0.71, 1.20), with overall stability at 72 months. No correlation between MBL and PES was observed. A significant association was found between thick gingival phenotype and less MBL variation. Greater implant diameter offered more MBL stability after 3 years but resulted in lower PES values. Conclusions: The use of convergent transmucosal neck implants placed with a flapless transmucosal approach with the crown margin positioned at the gingival level preserved marginal bone and guided gingival morphology for up to 72 months. The gingival phenotype was the parameter that most affected the soft and hard tissues. In the long term, implant placement timing was not related to MBL. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate and compare the difference in retention between implant-supported restorations with and without surface modification of the implant abutments. Materials and Methods: A total of 30 patients with singletooth implants were restored with cement-retained (Multilink N, Ivoclar) restorations using titanium base abutments (Variobase, Straumann) and randomly assigned surface modifications. Group 1 used nonmodified abutments, group 2 used sandblasted abutments, and group 3 used sandblasted abutments followed by an application of metal primer. All patients were recalled for a baseline examination 6 months after crown placement. The pull-out strength and intergroup distribution of mean pull-out strength were assessed. To assess differences between the three groups, intergroup statistical comparison of continuous variables was done using one-way ANOVA with Tukey correction for multiple group comparisons. Results: The results of the intergroup mean pull-out strength distribution revealed that the distribution of mean ± SD pull-out strength in group 1, group 2, and group 3 were 220.79 ± 94.23, 488.64 ± 84.12, and 705.46 ± 112.75 Ncm, respectively. Conclusions: Sandblasting followed by the application of metal primer produced the highest retention of porcelain-fused-to-metal (PFM) crowns to titanium base abutments, followed by sandblasting alone, with the least retention being observed with no surface treatment. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the effectiveness of coating of abutments with antimicrobial agents and their influence on the physicochemical and biologic properties of the coated materials. Materials and Methods: This work was registered in Open Science Framework (osf.io/6tkcp) and followed the PRISMA protocols. A search of two independent reviewers of articles published up to October 29, 2021, was performed in the Embase, PubMed, Science Direct, and Scopus databases. Results: The databases found a total of 1,474 references. After excluding the duplicates, 1,050 remained. After reading the titles and abstracts and applying the inclusion criteria, 13 articles remained and were read in full. A total of 8 articles were included in this systematic review. Different antimicrobial agents have been used to coat abutments, including graphene oxide, polydopamine, titanium and zirconium nitride, lactoferrin, tetracycline, silver, and doxycycline with varied release times. Titanium-coated silver showed a better antimicrobial agent release time of up to 28 days. Chemical analysis confirmed the presence of antimicrobials on the surface after coating. Different pathogenic microorganisms, such as Streptococcus sanguinis, Streptococcus oralis, and Staphylococcus aureus, were inhibited when in contact with the coated surface. Conclusions: This review showed that there is still no consensus on which is the better antimicrobial agent and which coated materials have the better performance. However, the association of surface coating of abutments with antimicrobials is feasible and can benefit many patients, which can support their clinical use to favor the healing process and prevent infections that can lead to treatment failure with dental implants. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study which evaluated the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation. Topics covered include master cast with the Giroform System, abutment duplication and the influence of duplication on crown marginal and internal adaptation.

Purpose: To determine the characteristics of dental implant transmucosal surfaces that influence soft tissue attachment and marginal bone loss (MBL). Materials and Methods: The PubMed, Embase, and Cochrane Library electronic databases were searched based on predefined PICO eligibility criteria. Data from animal studies that compared junctional epithelium and connective tissue attachment and MBL from 4 days to 72 weeks were analyzed. The risk of bias was performed with the Systematic Review Centre for Laboratory Animal Experimentation tool. A rank analysis evaluation of data was performed, and the most frequently appearing materials/surfaces for each tissue compartment were identified. Results: The search identified 3,549 studies, 28 of which were eligible for analysis, with an average risk of bias of 28% ± 10%. Machined, polished, etched, sandblasted, or coated titanium and zirconia materials/surfaces were most frequently examined. Several studies investigated lithium disilicate, polyether ether ketone (PEEK) or polyether ketone ketone (PEKK), aluminum oxide, and gold. Based on ranking and frequency of use at different time points, titanium grade IV (Ti-4) microthreads with a polished neck area most frequently supported natural tooth-like junctional epithelial attachment (= 1.5 mm), while machined Ti-4 and machined titanium grade V (Ti-5) most frequently supported connective tissue attachment (= 1.25 mm) and led to the least MBL (= 0.75 mm). Conclusions: Analyzed data suggest that Ti-4 microthreads with a polished neck area and machined Ti-4 and Ti-5 were the materials/surfaces of choice for the transmucosal part of implants. However, the extensive heterogeneity in reported studies precludes solid identification of the best materials/surfaces. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study investigated the effect of implant geometry and diameter on the rotational load fatigue performance of an implant system with an internal conical connection with microthreads. Materials and Methods: Regular (4.2 mm) and wide-diameter (4.8 mm) Astra Tech EV implants with straight (S) and conical (C) geometries were tested with their corresponding titanium abutments, comprising four test groups: 4.2-mm S (Group 1), 4.2-mm C (Group 2), 4.8-mm S (Group 3), and 4.8-mm C (Group 4). Five samples were included in each group. Customized brass implant holders and abutment holders were machined. A rotational load fatigue machine was used to apply a sinusoidally varying load to the implant-abutment interface at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz (air temperature: 20°C). The number of cycles to failure was recorded, with the upper limit set at 5 × 106 cycles. Results were analyzed using ANOVA. Failed samples were examined with a scanning electron microscope to evaluate the mode of failure. Results: Of the 20 total samples, 2 failed, with Groups 1 and 2 each reporting one failure. Abutment and abutment screw fracture were observed in the failed sample in Group 1, while implant and abutment screw fracture occurred in the failed sample in Group 2. All wide-diameter implants ran beyond the cut-off without failure, but abutment screw loosening was noted in one sample in Group 3. No significant difference was found between implant groups of different geometries and diameters. Damage to the abutments and the implant internal surface were noted in all failed samples. Conclusions: While no significant differences were found between the test groups, failures were observed only in the regular-diameter group. The abutment and abutment screw fractured deep within the implant, and the implant fractured below the simulated bone level. These modes of failure may pose a significant clinical challenge during retrieval of these components. [ABSTRACT FROM AUTHOR]

This study retrospectively evaluated the influence of prosthetic features on marginal bone level changes around bone-level implants with an external hex connection. A total of 100 patients with 166 implants and cemented crowns were included. Demographic and clinical data were collected. Prosthetic features were radiographically evaluated, including emergence angle (EA), emergence profile (EP), crown-implant ratio (CIR), and abutment height. Marginal bone levels were measured on intraoral radiographs taken at baseline and after at least 1 year. The correlation between prosthetic features and marginal bone loss (MBL) was then investigated. The mean follow-up time was 43.94 months. Implant length varied between 5 and 13 mm. The mean height of the abutments used was 1.55 mm. EA measured an average 30.62 degrees (± 13.20) mesially and 29.45 degrees (± 13.07) distally. The CIR was 0.99 (± 0.26). The mean MBL was 0.19 mm on the mesial side and 0.20 mm on distal side of the implants. Significant positive associations emerged between MBL and implant length (P < .005) and with EA (P < .05). A convex profile of the crown was shown to be associated with a higher distal MBL (P = .025) compared to concave and str aight profiles. [ABSTRACT FROM AUTHOR]

Purpose: To assess two types of abutment materials routinely used in daily practice--direct polymethyl methacrylate (PMMA) and a zirconia-on--Ti-base abutment--and their effects on peri-implant soft tissues and bone remodeling in a minipig model. Materials and Methods: A total of 40 implants were placed in five minipigs in a single-stage surgery. Four different types of abutment materials (n = 10 per group) were used: (1) titanium (control); (2) zirconia (control); (3) PMMA (test 1); and (4) Ti-base (zirconia bonded to a titanium framework; test 2). After 3 months of healing, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attachment) were assessed on each abutment mesially and distally, and the distance from the implant margin to the first boneto-implant contact (BIC) was measured. Results: No statistically significant differences were found among the four groups regarding soft tissue dimensions (P = .21), and a long junctional epithelium (mean: 4.1 mm) and a short connective tissue attachment (mean: 0.3 mm) were found in the majority of abutments. In some samples, the junctional epithelium extended all the way to the bone level. The measured peri-implant bone remodeling was similar in all four groups (P = .25). Conclusions: The present findings indicate that both direct PMMA and zirconia-on-Ti-base abutments seem to allow soft tissue integration similar to that of titanium and zirconia abutments. However, clinical studies are warranted to either confirm or refute the observed findings and to further investigate the influence of different materials on mucointegration. [ABSTRACT FROM AUTHOR]

This retrospective study evaluated the survival rate and the clinical outcome of an endosseous implant system, as well as the marginal bone level (MBL) and the impact of the machined collar neck position on crestal bone level changes up to 2 years later. A total of 96 implants were placed in 57 patients and loaded with a final restoration after at least 3 months of healing: 15 implants were immediately placed into fresh extraction sockets, and 81 were placed in healed ridges. Marginal bone loss around implants was determined radiographically at 12 to 24 months postloading. The effects on marginal bone loss of the site (mandible vs maxilla), location (anterior vs posterior), immediate vs delayed implant, smoking habit, sex, implant length and diameter, prosthesis type (screw-retained/cemented), and the machined collar position were evaluated. The implant survival rate was 98.96% at 1 year. The mean MBL decreased significantly (0.238 mm) between baseline and loading (P < .001; post hoc test) and decreased by 0.154 mm between loading and 1 year, but this was not significant (P = .085; post hoc tests). After 2 years, the mean MBL decreased significantly (0.263 mm) between baseline and loading (P < .001) and decreased by 0.111 mm between loading and 1 year and by 0.199 mm between loading and 2 years, but these were not significant (P > .05; post hoc tests). The mean bone loss after 1 and 2 years was not significantly associated with implant type or site, smoking habit, or type of implant surgery (P = .792). However, the mean bone loss was significantly associated with the type of prosthesis and was significantly greater for cemented prostheses compared to screw-retained prostheses. A supracrestal position of the machined collar (tissue level) was associated with no bone loss, while placing the collar below the alveolar crest led to bone loss over 2 years. Of the factors evaluated, marginal bone loss after 1 and 2 years was significantly associated with prosthesis type and the machined collar position. [ABSTRACT FROM AUTHOR]

Purpose: To examine the stresses caused by different All-on-4 surgical techniques—conventional, a combination of monocortical and bicortical, bicortical, and nasal floor elevation—on the implant and the surrounding bone using 3D finite element analysis (FEA). Materials and Methods: A 3D bone model of the atrophic maxilla was created based on CT imaging of the fully edentulous adult patient. All implants used in the models were 4 mm in diameter, and the length was 13 mm in the anterior and 15 mm in the posterior. Implants were applied to four different atrophic maxillary models with the All-on-4 technique: anterior and posterior monocortical implants in the first model, anterior monocortical and posterior bicortical in the second model, anterior and posterior bicortical in the third model, and anterior and posterior bicortical with nasal floor elevation in the fourth model. Eight linear analyses were performed by applying force from both vertical and 45-degree oblique directions to the four models prepared in our study. Results: When the cortical and cancellous bone around the anterior implants was examined, it was observed that the oblique and vertical loading conditions and the stresses around the implant were similar in all models. When the posterior implants were examined, model 1 (ie, anterior and posterior monocortical implants) showed the greatest oblique compression, vertical compression, and vertical tension forces. According to the Von Mises stress (VMS) analysis results for anterior and posterior implants, higher values were observed in model 1 compared to models 3 and 4 under oblique and vertical forces. It was observed that bicortical placement of the implants reduced the stresses on the bone and implant-abutment system but had no significant effect on the stress on the bar. Conclusions: According to the results of our study, in the All-on-4 technique, bicortical placement of the implants reduced the stresses on the bone and implant when the anatomical limitations allowed. In addition, nasal floor elevation can be applied in the atrophic maxilla in appropriate indications. [ABSTRACT FROM AUTHOR]

The purpose of this clinical study was to assess the feasibility of forced orthodontic extrusion with the Tissue Master Concept to retain subgingivally fractured teeth as abutments for which extraction and replacement would be equal treatment opportunities. Participants were recruited from a group of consecutive patients in need of prosthodontic rehabilitation. In total, 36 deeply destroyed teeth in 31 patients underwent forced orthodontic extrusion with forces exceeding 50 g to reestablish biologic width and ensure a 2-mm dentin-ferrule design prior to single-crown restoration. The primary endpoint was the success of the extrusion in terms of the ability to restore the respective abutment tooth. Information about overall treatment time, frequency, and reasons for failure were collected. Four patients dropped out of the treatment. For the remaining 27 participants, data were fully collected. The amount of extrusion ranged between 2 and 6 mm (3.5 ± 0.9 mm), and the mean duration until retention was 20 ± 12 days. On average, patients returned three (± 3) times for control visits after extrusion. Adhesive failure (n = 6) and orthodontic relapse (n = 2) were the most frequent complication types. Forced orthodontic extrusion may be a useful tool to restore teeth evaluated as nonrestorable. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the peri-implant outcomes of customized healing abutments (CstHA) placed on dental implants inserted in fresh tooth extraction sockets. Materials and Methods: The study was registered on PROSPERO: CRD42022304320. A systematic search in PubMed, Scopus, and Web of Science was conducted between April 2022 and October 2022 to identify clinical studies involving immediate implant surgery associated with CstHA placement. The Joanna Briggs Institute Critical Appraisal and RoB2 tool were performed for the risk of bias analysis. Results: A total of 12 studies were included, most of them with low risk of bias. Four studies compared CstHA vs conventional healing abutments (CnvtHA), two compared CstHA vs cover screw and collagen matrix (CMa), and six were clinical case series. For the CstHA vs CnvtHA comparison, favorable results were observed for CstHA considering papilla maintenance and probing depth, yet the mean marginal bone level was statistically similar between CstHA and CnvtHA. CstHA showed advantages when compared to CMa for total bone volume, papilla height, and midfacial mucosa maintenance. Significantly less horizonal bone loss was reported when using CstHA compared with CMa. Horizontal and vertical bone loss was observed in a few (or no) sites in the case series using CstHA. Conclusions: CstHA provides favorable peri-implant response because in general it does not result in a significant loss of soft and hard tissues. [ABSTRACT FROM AUTHOR]

Purpose: To compare the fit of 3D-printed titanium (Ti) and cobalt-chromium (Co-Cr) abutments with implants to computer numerical control (CNC)-milled, ready-made abutment-implant assemblies. Their clinical applicability was also evaluated by measuring removal torque values (RTVs) and percentage torque loss of abutment screws. Materials and Methods: A total of 138 abutments were included in the study: 92 abutments were fabricated with Ti and Co-Cr alloys using computerassisted design (CAD) through selective laser melting, and 46 ready-made abutments were prepared. The fit of interfaces between 90 abutments from the three groups (30 ready-made, 30 3D-printed Ti, and 30 3D-printed Co-Cr abutments) and implant assemblies was demonstrated by scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). After 30-Ncm torque tightening of Ti abutment screws twice within 10 minutes, the RTVs and percentage torque loss of screws of 48 abutments (16 ready-made, 16 3D-printed Ti, and 16 3D-printed Co-Cr) were evaluated after 10 minutes of thermocycling and cyclic loading. Results: The fits of 3D-printed Co-Cr abutments were not statistically different from those of ready-made abutments (P = .383), while the fit of 3D-printed Ti abutments was inadequate (P < .001). The RTVs of 3D-printed abutments after cyclic loading were significantly decreased compared with those of CNC-milled abutments (P < .001). Conclusion: The fit of interfaces between 3D-printed Co-Cr abutments and implants was adequate. The RTVs of 3D-printed Co-Cr abutments were not significantly different from those of CNC-milled abutments after 10 minutes of 30-Ncm torque tightening and thermocycling. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the bone level changes in a new implant design (fully tapered with platform switching) with the one-abutment one-time protocol after 1 year of loading. Materials and Methods: Thirty patients received 1 or 2 implants (6-, 8-, or 10-mm length and 3.5-, 3.75-, or 4.5-mm diameter, bone-level design) to replace one or multiple edentulous sites. Only the mesial implant was assessed. Radiographic, clinical, and esthetic results and the survival and success rates were evaluated 1 year after final loading. Results: At 1 year, no peri-implant bone loss was seen in any of the cases. Mean marginal crestal bone loss between surgery and crown placement was 0.19 ± 0.17 mm (P < .0001). Between surgery and the 1-year follow-up, the mean marginal crestal bone loss was 0.25 ± 0.24 mm (P < .0001). The difference in the modified Plaque Index between 1 year of follow-up and crown placement was significant for in the mesial (0.33 ± 0.54 mm; P = .003) and distal surfaces (0.5 ± 0.73 mm; P = .001). The probing pocket depth was statistically significantly deeper at 1 year than at crown placement at the mesial and distal aspects (average depth = 0.75 mm; P < .0005). No statistically significant differences were found for any other clinical or esthetic parameters. The overall survival and success rates after 1 year were 100%. Conclusions: The fully tapered, deep-thread, platform-switched implant design placed with the one-abutment one-time protocol demonstrated minimal marginal crestal bone loss and crestal bone stability at 1 year of follow-up. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Materials and Methods Results Conclusion Clinical Significance This study compares the restoration of single‐tooth implants with screw‐retained lithium‐disilicate hybrid‐abutment crowns and single‐tooth lithium‐disilicate crowns adhesively bonded to hybrid abutments with regard to objective clinical and subjective patient‐specific evaluation criteria over a time of observation of 3 years.Two bone‐level implants were placed in contralateral sides of the same jaw in 10 patients, each with two single‐tooth gaps. After osseointegration, implants were uncovered and an impression was taken. In accordance with the split‐mouth design, one implant in each patient was restored with a screw‐retained hybrid abutment crown and the other implant with a hybrid abutment and an adhesively bonded single‐tooth crown. The restorations were randomly allocated to the implants. Prefabricated titanium bases were used. The ceramic abutments and restorations were fabricated monolithically with pressed lithium‐disilicate ceramic. An objective evaluation (survival, technical, or biological complications, FIPS) by the practitioner and a subjective evaluation (satisfaction, OHIP) by the patient were carried out after 3, 6, 12, 24, and 36 months after restoration placement.Both restoration types showed a survival rate of 100% after 3 years of observation. No technical or biological complications occurred. No significant difference was observed between the two types of restoration neither for objective (survival, technical or biological complications, FIPS) nor subjective (satisfaction, OHIP) evaluation criteria (p > 0.05).No statistically significant differences were observed between screw‐retained and cemented pressed lithium‐disilicate restorations on bone‐level implants for both objective and subjective evaluation criteria, respectively.Monolithic hybrid‐abutment crowns (screw‐retained) and monolithic hybrid abutments with single‐tooth crowns (cemented) made of pressed lithium disilicate can be used to successfully restore single implants. [ABSTRACT FROM AUTHOR]

Background: The current trial evaluated the midfacial gingival margin changes, volumetric, radiographic and clinical alterations 1-year following immediate implant placement with customized healing abutment (IIP + CHA) either solely, or in combination with xenograft (IIP + Bonegraft) or with connective tissue grafting (IIP + CTG) at sites with thin labial bone in the esthetic zone. Methods: Thirty-nine non-restorable maxillary teeth indicated for extraction in the esthetic zone were included. Participants were randomly assigned into three equal group; IIP + Bonegraft (Control), IIP + CTG and IIP + CHA. Midfacial gingival margin changes(mm) as primary outcome, labial soft tissue contour change(mm), interdental tissue height changes and total volume(mm3) were assessed. Amount of bone labial to the implant and crestal bone level changes were also recorded. All outcomes were measured 1-year post-operative. Results: The midfacial gingival margin changes demonstrated a significant difference (P ≤ 0.05) between the groups showing -0.98, -0.74 and -1.54 mm in sites treated with IIP + Bone graft, IIP + CTG and IIP + CHA respectively after1-year. While labial soft tissue contour change (mm), total volume (mm3) and distal interdental tissue height changes (mm) revealed a significant difference after one-year between the studied groups, yet mesial interdental tissue height changes showed no difference (P > 0.05). Both IIP + Bone graft and IIP + CHA groups revealed a significant positive correlation between the total volume loss (mm3) after 1 year and mid-facial gingival margin changes (P ≤ 0.05). However, no significant correlation was observed in the IIP + CTG group (P = 0.63). CBCT measurements showed a significant difference in crestal bone changes between the three groups (P ≤ 0.05), yet, there was no significant difference regarding mean amount of bone labial to the implant(P > 0.05). Conclusions: This investigation suggests that the mere presence of CTG simultaneous with IIP in the anterior maxilla reduced the midfacial gingival margin alterations (mm), besides, CTG decreased the overall volume loss (mm3) by 5-folds compared to the other studied groups after one year. Meanwhile, using CHA alone with IIP failed to maintain the peri-implant soft tissues contour. Trial registration: The current trial was retrospectively registered at Clinical trials.gov (ID: NCT05975515, Date: 27-July-2023). [ABSTRACT FROM AUTHOR]

Background: The passive fit of 3-unit implant supported prefabricated metal screw-retained prosthesis before implant placement might be difficult. Hence, we aim to evaluate the passive fit and time efficiency of CAD/CAM 3-unit implant supported fixed prostheses that were constructed based on virtual versus those based on actual implant positions in Kennedy Class I models. Methods: A sample of 5 Kennedy class I models with thin wiry ridges were restored by 20 frameworks bilaterally, 10 based on actual (group A) and 10 based on virtual (group V) implant positions. The models were imaged using cone beam computed tomography and scanned using an intraoral scanner. The STL (Standard Tessellation Language files) and the DICOM (Digital Imaging and Communications in Medicine) files were registered on a 3D planning software. A CAD/CAM surgical guide was planned, resin printed and used for installing 6 implants bilaterally. In group V, the framework was designed based on the virtual scan bodies and virtual multi-unit abutments, while in group A intra-oral scanning of the model after attaching the scan bodies was necessary. Frameworks of both groups were milled and tested for passive fit using 8 clinical tests. McNemar and Wilcoxon signed rank tests were used to study the effect of the group on passive fit and time efficiency, respectively. The significance level was set at P ≤ 0.05. Results: No statistically significant difference was found between group V and group A frameworks regarding passive fit (p-value = 1, OR = 0.5) and time efficiency (P = 0.179, Effect size = 0.948). Conclusion: Within the limitations of this study, it can be concluded that in free end saddle cases, prefabricated CAD\CAM 3-unit implant-supported cobalt chromium screw retained prostheses can achieve an adequate passive fit. However, their fit might be negatively affected in thin ridges and they might require some adjustments. [ABSTRACT FROM AUTHOR]

Background and Objectives: The aim of this study was to evaluate the influence of abutment angulation, types, and bone quality on fatigue performance in dental implant systems. Materials and Methods: Three-dimensional models of maxillary 3-unit fixed implant-supported prostheses were analyzed. Abutments with different angles and types were used. Healthy bone (Hb) and resorbed bone (Rb) were used. Conducted on implants, a force of 150 N was applied obliquely, directed from the palatal to the buccal aspect, at a specific angle of 30 degrees. The stress distribution and fatigue performance were then evaluated considering the types of bone used and the angles of the three different abutments. The simulation aspect of the research was carried out utilizing Abaqus 2020 software. Results: In all models, fatigue strengths in healthy bone were higher than in resorbed bone. Maximum stress levels were seen in models with angled implants. In almost all models with resorbed bone, fatigue performances were slightly lower. Conclusions: Increasing the abutment angle has been shown to increase stress levels and decrease fatigue performance in the adjacent bone and along the implant–abutment interface. In general, implants applied to healthy bone were found to have a higher success rate. It has also been suggested that multiunit abutments have beneficial effects on stress distribution and fatigue performance compared to resin cemented abutments. The type or angle of abutment and the quality of the bone can lead to biomechanical changes that affect the force distribution within the bone structure surrounding the implant. Clinicians can influence the biomechanical environment of the implant site by varying the abutment angle and type to suit the condition of bone health, potentially affecting the long-term success of implant treatment. [ABSTRACT FROM AUTHOR]

Objective: The aim of this investigation was to evaluate the effect on clinical and radiological outcomes of the one‐abutment, one‐time protocol (test) versus placing the definitive abutment on the day of functional loading after having disconnected and connected three times the healing abutment during the prosthetic phase (control). Materials and methods: Forty patients with 80 implants were randomly allocated to either the test or the control group. Changes in the radiographic marginal bone levels (MBLs), clinical outcomes, prosthetic‐related outcomes, and patient‐reported outcomes measures (PROMs) were assessed and compared 6 and 12 months after functional loading. Results: Thirty‐seven patients with 74 implants were followed at 12 months. A statistically significant bone remodeling was observed in both groups following implant placement. MBLs were significantly greater in the control group at the 6‐ (−0.13 mm vs. −0.61 mm) and 12‐month visits (−0.01 mm vs. −0.53 mm). Bone loss was significantly greater in the control group from surgery to 6 and 12 months and from loading to 6 and 12 months. The abutment height was significantly greater in the test group, however, there were no significant differences in the restorative angle. Similarly, there were no statistically significant differences between groups for the measured clinical variables (probing depth, plaque, and bleeding index) and PROMs. Conclusions: Disconnecting and reconnecting the healing abutment was associated with significantly higher bone loss after 12 months, as compared to the placement of the definitive abutment at implant installation. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of the deterioration of computer aided design/computer aided manufacturing (CAD/CAM) burs during zirconia milling, on surface roughness, contact angle, and fibroblast viability. Materials and Methods: Ceramic blocks were milled and 75 ceramic disks (8 × 1.5 mm) made and allocated into three groups (n = 25): G1‐brand new 2L and 1L burs, G2‐2L bur at the end of lifetime and brand new 1L bur and G3‐both burs at the end of their lifetimes. Roughness (Ra, Rq, and Rz) was evaluated using a 3D optical profilometer, the contact angle by the sessile drop method and the cell viability of the mouse NIH/3T3 fibroblast, using the Alamar Blue assay at intervals of 24, 48, and 72 h (ISO 10993‐5). Data were analyzed by one‐way ANOVA and Kruskal–Wallis tests (p ≤ 0.05). Results: Roughness increased as the burs deteriorated and G3 (0.27 ± 0.04) presented a higher value for Ra (p < 0.001). The highest contact angle was observed in G3 (86.2 ± 2.66) when compared with G1 (63.7 ± 12.49) and G2 (75.3 ± 6.36) (p < 0.001). Alamar Blue indicated an increase in cell proliferation, with no significant differences among the groups at 24 and 72 h (p > 0.05). Conclusions: The deterioration of the burs increased the surface roughness and decreased the wettability, but did not interfere in cell viability and proliferation. Clinical Significance: The use of custom zirconia abutments represents an effective strategy for single crowns restorations. Our findings suggest that these abutments can be efficiently milled using CAD/CAM burs within their recommended lifetime. [ABSTRACT FROM AUTHOR]

Objective: Dental implants placed in adolescent patients pose a challenge to restore and maintain an esthetic outcome over longer period of follow‐up. Maxillomandibular changes throughout adulthood may lead to complications such as implant infraocclusion and interproximal contact loss. This case report describes an alternate prosthetic treatment strategy for maxillary single implant placed in an adolescent patient in the esthetic zone with inappropriate implant axis and screw hole placement. Clinical considerations: With temporary restorations, the gingiva and soft tissues were shaped to imitate the emerging profile of the contralateral side. A zirconia screw‐retained abutment was customized as a copy‐mirror from the contralateral prepared tooth to mimic the exact shape and to avoid labiolingual over contour by computer‐aided design/computer‐assisted manufacture (CAD/CAM). The porcelain laminate veneer was bonded to the zirconia abutment. Porcelain adhesive approach was used instead of traditional principles of retention and resistance form of the abutment. Conclusions: A functional and esthetic outcome was achieved and maintained, while a minimally invasive procedure was implemented to use the malplaced implant instead of explanting it. Clinical significance: The present report illustrates the prosthetic management of a malpositioned dental implant placed 20 years ago, utilizing a minimally invasive digital protocol. [ABSTRACT FROM AUTHOR]

This is the first article in a three-part series that discusses joint orthodontic–restorative care for the adult patient. Part 1 presents an overview of the clinical presentations, challenges and strategies that may be employed to treat this complex patient group. CPD/Clinical Relevance: The reader should be able to describe a care pathway, with potential associated complications, for the provision of adult orthodontic–restorative treatment. [ABSTRACT FROM AUTHOR]

Objective: This study assessed the effect of the anodization of titanium abutments on the color parameters and color difference of lithium disilicate (LDS) all‐ceramic crowns. Materials and Methods: In this study, 19 straight abutments were divided into two groups: anodized (n = 9) and non‐anodized control (n = 9), with one hybrid zirconia abutment as a reference. Anodization was achieved by applying 63 V energy using seven 9 V flat batteries in series, with an electrolyte solution comprising 1 g trisodium phosphate in 250 mL distilled water for 5 s, resulting in a gold‐yellow color. Abutments were then scanned, and full‐contour monolithic IPS e.max maxillary central incisor crowns were fabricated with 2 mm thickness and glazed. Reflectance was measured using a spectroradiometer, and color coordinates (L*, a*, b*, h*, and C*) were calculated using CS‐10W software. Color differences of the crowns in both groups were quantified using the CIEDE2000 (ΔE00) color difference formula and analyzed by t‐test (α = 0.05) compared to the standard sample. Results: The L*, a*, b*, and c* parameters in anodized abutments were significantly higher than those in non‐anodized abutments, while the h* parameter in anodized abutments was significantly lower than that in non‐anodized abutments (p < 0.001 for all). There was a significant difference in ΔE00 of the two groups (p = 0.043). Conclusion: Anodization of titanium abutments improved the color parameters of LDS all‐ceramic crowns and significantly decreased their ΔE compared with non‐anodized abutments. Clinical Relevance: The research findings indicate that the anodization of titanium abutments significantly impacts color parameters, leading to lighter, redder, and more color‐saturated samples compared to non‐anodized ones. This suggests that anodization can optimize color matching in dental restorations, particularly in esthetic dentistry where precise color reproduction is crucial for natural‐looking results. Implementing anodization techniques may enhance the overall esthetic outcomes of dental prosthetics, providing clinicians with a valuable tool to improve patient satisfaction and confidence in their smiles. [ABSTRACT FROM AUTHOR]

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Background: In edentulous jaws, factors such as the number of implants, cross-arch distribution, and the angle among implants may affect the accuracy of the implant impression. This study explored factors influencing the accuracy of implant abutment-level digital impressions using stereophotogrammetry in edentulous jaws. Methods: Two standard all-on-4 and all-on-6 models of edentulous jaws were constructed in vitro. In the stereophotogrammetry group (PG), the implant digital impression was made using stereophotogrammetry and saved as an STL file. In the conventional group (CNV), the impression was made using the open-tray splint impression technique. An electronic and optical 3D measuring instrument was used to scan the standard model and the conventional plaster model to obtain STL files. Using 3D data processing software (GOM Inspect Pro, Zeiss), the distance and angle between the abutments in the CNV impression and the PG impression were measured and compared with the data from the standard model. Results: The distance deviation in the PG and the CNV was 145 ± 196 μm and 96 ± 150 μm, respectively, with a significant difference (P < 0.001). The angle deviation in the PG and the CNV was 0.82 ± 0.88° and 0.74 ± 0.62°, respectively, with no significant difference (P = 0.267). In the PG, the distance deviation was negatively correlated with the distance between implants (r = -0.145, P = 0.028) and positively correlated with the angle of implants (r = 0.205, P = 0.002). The angle deviation was negatively correlated with the distance between implants (r = -0.198, P = 0.003) and positively correlated with the angle of implants (r = 0.172, P = 0.009). In the CNV, the effect of inter-implant distance on impression accuracy was also shown by Spearman correlation analysis: r = 0.347 (P < 0.001) for distance deviation and r = -0.012 (P = 0.859) for angle deviation. The effect of inter-implant angulation on impression accuracy deviation was r = -0.026 (P = 0.698) for distance deviation and r = 0.056 (P = 0.399) for angle deviation. Conclusions: The CNV method is closer to the real value of the original model. The distance between implants and the distribution angle had a weak correlation with the accuracy of digital impressions but no significant correlation with the accuracy of traditional impressions. [ABSTRACT FROM AUTHOR]

Background: Failure to restore missing teeth in time can easily lead to the mesial tilting of the distal abutment teeth. However, a fixed partial denture (FPD) can improve stress conduction and distribution and prevent periodontal injuries. In these more complex cases, it is necessary to consider various factors comprehensively to improve conventional treatment planning and achieve better results. Methods: We selected a patient with a missing first molar and a mesial inclination of the second molar, leaving inadequate space or bone mass for implant denture restoration, necessitating an FPD for restoration. Three-dimensional finite element analysis (3D-FEA) combined with photoelastic analysis were used to explore how the inclination angle (0 ‒ 30°) and different dental restoration materials (zirconia, lithium disilicate, polymer-infiltrated ceramic network, and resin composite) affect the biomechanical behaviour of FPD‒abutments‒periodontal tissue complex. Results: The stress was easily concentrated in the FPD connectors, enamel shoulder collar, periapical area, and root bifurcation. The stress on FPD and the periodontal ligament (PDL) of the second premolar increased with an increase in the elastic modulus of FPD, with an opposite trend in the abutments, the alveolar bone, and the PDL of the second molar. The stress on the FPD and alveolar bone increased with increased inclination angle of the distal abutment. The stress on two abutments and their PDL were positively correlated with the inclination angle in two stages; however, when the inclination angle > 12°, the second premolar and its PDL showed a negative correlation. Conclusions: FPDs can be used for restoration within 24° of distal abutment inclination, but protecting the abutments (< 12° especially) and the periodontal tissue (> 12° especially) must be taken seriously. For this purpose, an FPD material with higher strength is recommended. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to evaluate the effect of using different types of metallic and non-metallic telescopic crown attachment materials on wear resistance and surface tomography changes in implant-retained mandibular overdentures. Materials and methods: Completely edentulous mandibular epoxy models were fabricated, in which two implants were placed in the canine region and retained to the implants with three different material combinations used for the construction of telescopic attachments. Thirty-three identical mandibular overdentures were fabricated using the conventional standardized technique. The study groups were divided into three categories according to the material used for the construction of the secondary copings. The primary copings in all the study groups were constructed of PEEK, while the secondary coping in group I was PEEK, group II was ZrO2 and CoCr for group III. Primary copings were cemented on a ready-made abutment. Secondary copings were placed over the primary copings in the desired path of insertion, then picked up into the intaglio surface of the overdentures. A cyclic loading machine was used to apply repeated insertion-removal cycles simulating nearly 10 years of clinical use. Stereomicroscope with a built-in camera was used to monitor the reduction in width of the primary copings to evaluate the wear resistance of each material combination. Results: There was highly statistically significant difference between the study groups after the application of 1.000, 5.000 and 10.000 cycles. The highest level of wear resistance was recorded for the PEEK/PEEK combination, whereas PEEK/ZrO2 and PEEK/CoCr showed no significant differences. Conclusions: Implant retained overdenture with PEEK-PEEK telescopic crown attachment is associated with the highest wear resistance among all the study groups. PEEK-PEEK combination may be the treatment of choice for fabrication of telescopic attachment in implant retained overdenture as it provides better resistance to wear. It offers the advantages for geriatric patients as it decreases the possibility for repeated repair and replacement of attachment, increase long-term patient satisfaction and shelf life of prosthesis. [ABSTRACT FROM AUTHOR]

Virtual reality is considered to be useful in improving procedural skills in dental education, but systems using wearable devices such as head-mounted displays (HMDs) have many problems in terms of long-term use and hygiene, and the accuracy of stereoscopic viewing at close ranges is inadequate. We developed an abutment tooth formation simulator that utilizes a display (spatial reality display—SRD) to precisely reproduce 3D space with naked-eye stereoscopic viewing at close range. The purpose of this was to develop and validate the usefulness of an abutment tooth formation simulator using an SRD. A 3D-CG (three-dimensional computer graphics) dental model that can be cut in real time was output to the SRD, and an automatic quantitative scoring function was also implemented by comparing the cutting results with exemplars. Dentists in the department of fixed prosthodontics performed cutting operations on both a 2D display-based simulator and an SRD-based simulator and conducted a 5-point rating feedback survey. Compared to the simulator that used a 2D display, the measurements of the simulator using an SRD were significantly more accurate. The SRD-based abutment tooth formation simulator received a positive technical evaluation and high dentist satisfaction (4.37), suggesting its usefulness and raising expectations regarding its future application in dental education. [ABSTRACT FROM AUTHOR]

Background: Advancements in digital dentistry helped in custom-milling screw-channels in implant-supported restorations; however, the fit of these restorations is still unclear especially for contemporary computer aided designing/computer aided manufacturing (CAD/CAM) materials. This study aimed to compare the internal and marginal fit of Ultra translucent multilayered zirconia versus lithium disilicate implant-supported hybrid abutment crowns (HACs) constructed with custom-milled screw-channels on Titanium-base. Materials and methods: A total of 24 HACs with custom-milled screw-channels were constructed from lithium disilicate (Group LDS) and Ultra translucent multilayered zirconia (Group UT) using digital workflow (n = 12). The internal and marginal gaps of HACs on their corresponding Titanium-bases were assessed using replica technique and stereomicroscope, respectively. After testing for normality, quantitative data were expressed as mean and standard deviation and compared using independent t-test at a level of significance (P ≤ 0.05). Results: There was no statistically significant difference between Group LDS and Group UT in terms of marginal and internal fit. The internal and marginal gaps in both groups were within the accepted values reported in literature. Conclusions: UT and LDS HACs with custom-milled screw-channels demonstrated comparable and acceptable internal fit and marginal adaptations to Ti-base, which lied within the range reported in literature. [ABSTRACT FROM AUTHOR]

Background: The purpose of this in vitro study was to investigate the effect of polishing post-treatment process on the torque loss ratio and microgap of Selective Laser Melting (SLM) abutments before and after mechanical cycling test through improving the surface roughness of the implant-abutment interface. Materials and methods: Forty SLM abutments were fabricated, with 20 underwent minor back-cutting, designated as polishing, in the implant-abutment interface. The abutments were divided into three groups: SLM abutments (group A), original abutments (group B), and polished SLM abutments (group C), each containing 20 abutments. Surface roughness was evaluated using a laser microscope. Implant-abutment specimens were subjected to mechanical cycling test, and disassembly torque values were measured before and after. Scanning electron microscope (SEM) was used to measure microgap after longitudinal sectioning of specimens. Correlation between surface roughness, torque loss ratio, and microgap were evaluated. LSD's test and Tamhane's T2 comparison were used to analyze the data (α = 0.05). Results: The Sz value of polished SLM abutments (6.86 ± 0.64 μm) demonstrated a significant reduction compared to SLM abutments (26.52 ± 7.12 μm). The torque loss ratio of polished SLM abutments (24.16%) was significantly lower than SLM abutments (58.26%), while no statistically significant difference that original abutments (18.23%). The implant-abutment microgap of polished SLM abutments (2.38 ± 1.39 μm) was significantly lower than SLM abutments (8.69 ± 5.30 μm), and this difference was not statistically significant with original abutments (1.87 ± 0.81 μm). A significant positive correlation was identified between Sz values and the ratio of torque loss after cycling test (r = 0.903, P < 0.01), as well as Sz values and the microgap for all specimens in SLM abutments and polished SLM abutments (r = 0.800, P < 0.01). Conclusion: The findings of this study indicated that the polishing step of minor back-cutting can lead to a notable improvement in the roughness of SLM abutments interface, which subsequently optimized the implant-abutment fit. It can be seen that the application of minor back-cutting method has advanced the clinical use of SLM abutments. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the mechanical performance of patient‐specific prefabricated temporary shell versus laboratory‐fabricated CAD/CAM provisional restorations on titanium temporary abutments, with and without thermo‐mechanical ageing. Materials and Methods: Implants with a conical connection were divided into four groups (n = 24) and restored with temporary shell or laboratory‐fabricated central or lateral incisor PMMA restorations that were relined or bonded on titanium temporary abutments. The diameter of the central and lateral incisor groups' implants was regular (ϕ 4.3 mm) or narrow (ϕ 3.5 mm), respectively. Half of each group's specimens were subjected to ageing, simultaneous thermocycling (5–55°C) and chewing simulation (120,000 cycles, 50 N, 1.7 Hz) resulting in eight groups in total (n = 12). The aged specimens were evaluated with optical microscopy, and survival and complication rates were determined according to modified USPHS criteria. The non‐aged specimens and those that had survived ageing were loaded until failure, whereupon bending moments were calculated. Results: Survival rates after ageing were 100% for all groups. Apart from wear facets (ϕ 2–3 mm) on the palatal restoration surface, no complications were observed. The mean fracture load and bending moments ranged between 597.6–847.1 N and 433.3–550.6 Ncm, respectively, with no significant differences between the eight groups (p =.25; p =.20). Conclusions: As patient‐specific temporary shell central and lateral incisor provisional implant‐supported restorations are mechanically stable enough to withstand clinical bite forces, even after thermo‐mechanical ageing, they may serve as an alternative to laboratory‐fabricated provisional restorations. [ABSTRACT FROM AUTHOR]

Transferring the intraoral situation accurately to the dental laboratory is crucial for fabricating precise restorations. This study aimed to compare the dimensional accuracy of a new hydrophilic quadrofunctional vinyl polysiloxane (VPS) and polyether (PE), in combination with different impression techniques (mono-phase single step or dual-phase single step). The reference model simulated a partially edentulous mandible. Stainless-steel precision balls were welded to specific teeth and were used to detect dimensional deviations. Fifteen impressions were made for each of the following four test groups: (1) VPS mono-phase, (2) PE mono-phase, (3) VPS dual-phase, and (4) PE dual-phase. Global accuracy was measured by deviations from the reference model, while local accuracy focused on the trueness and precision of abutment tooth surfaces. Statistical analysis was conducted using ANOVA (α = 0.05). All distances were underestimated, with the highest global inaccuracies for the cross-arch distance, ranging from −82 µm to −109 µm. The abutment tooth surfaces showed excellent local accuracy for all the materials and techniques, with crown surface trueness < 10 µm and precision < 12 µm. Inlay surfaces had higher inaccuracies (trueness < 15 µm, precision < 26 µm). Within the limitations of this study, all impression materials and techniques can be used to produce models with clinically acceptable accuracy. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the influence of translucent monolithic versus bilayered crowns and whether the use of a CoCr base abutments affects the fatigue and fracture resistance of screwed implant‐supported single crowns with external connections under mechanical cycling. Materials and Methods: Fifty specimens were divided into groups: (1) metal–ceramic (MC) crown, (2) veneered zirconia crown (Zr), (3) veneered zirconia crown with a CoCr base abutment (ZrB), (4) monolithic translucent zirconia crown (MZr), and (5) monolithic translucent zirconia crown with a CoCr base abutment (MZrB). Specimens underwent mechanical cycling (5 × 106 cycles; 150 N) evaluating fatigue resistance (number of failures) and those that failed were subsequently subjected to fractographic analyses (stereomicroscope and scanning electron microscope) to evaluate failure location and area, and maximum fracture load was also measured. Results: The failure‐related survival rate (100%) and maximum fracture resistance of the MZrB were significantly higher than those of MC and Zr (50%; p < 0.05). There were no significant differences in the failure rate and fracture resistance when a CoCr base abutment was used or not in the translucent monolithic Zr groups (p > 0.05;MZrB vs. MZr). Failure location, with MC crowns' fractures, noted at the screw area (p = 0.043), while all‐ceramic crowns were mostly in the cuspid and to failure area, the Zr group had the largest mean (15.55 ± 9.17 mm2) among the groups, significant difference only when compared with MC (1.62 ± 0.81 mm2) (p = 0.025). Conclusions: Translucent monolithic zirconia crowns exhibited significantly higher fatigue and fracture resistance compared with conventional MC and bilayered crowns. Clinical Significance: The appropriate choice of material and manufacturing technique is crucial for predicting the higher clinical performance of single crowns. Enhanced mechanical resistance in terms of fatigue and fracture resistance can be achieved by replacing MC and bilayered restorations with computer‐aided design and computer‐aided manufacturing monolithic zirconia. [ABSTRACT FROM AUTHOR]

To evaluate structural damage and loosening of abutments placed on narrow diameter implants after cyclic fatigue. Sixty Morse taper narrow diameter implants (Neodent, Brazil) received two types of abutments (1PA- one-piece abutment or 2PA- two-piece abutment), which were randomly divided into 3 fatigue experiments (n = 10). The implants were placed into a customized supporting holder and a software-assisted digital torque wrench secured the manufacturer recommended torque for each abutment. Cone beam computed tomography (CBCT) scans were acquired, before and after fatigue, and post-processed (software e-Vol DX) to assess damage and abutment displacement. The boundary fatigue method was adapted to use 2 × 106 cycles, 2 Hz of frequency and constant peak load of 80 N (first experiment) that varied according to the failure rate of previous specimens (second and third experiments). Failure was evaluated using CBCT scans and removal torque values. Data were used to estimate long-term torque degradation, probability of failure and Weibull modulus (software ALTA PRO9). All 2PA specimens became loosen independently of the applied fatigue load, and structural bending was observed in 14 abutments. Eight 1PA got loosen during the fatigue experiment. The Weibull analysis showed a lower modulus (m = 1.0; 0.7, 1.4) for 1PA than for 2PA (m = 2.6; 2, 3.4) resulting in longer predicted lifetimes and slower torque degradation for 1PA than for 2PA specimens. 1PA showed greater long-term survival probability than 2PA. Predicting the lifetime and mechanical behavior of implant-abutment systems are useful information to clinicians during the decision-making process of oral rehabilitations. • The abutment type influences the survival probability of the implant-abutment system. • The applied method can predict the lifetime and long-term behavior of the systems. • Improved CBCT images can assist on diagnosing loosening and damage of implant-abutment. [ABSTRACT FROM AUTHOR]

The aim of the present work was to evaluate retrospectively, after seven years of function, the efficacy of a conometric retention to stabilize complete prostheses (CPs) on four implants. Data from twenty-three patients with CPs supported by four implants, with at least seven years of follow up were retrieved. All the CPs were immediately fixed to the implants using a conometric retention. Outcome measures were prosthesis and implant success, biological and prosthetic complications, probing pocket depth changes, marginal bleeding, and plaque index changes. A total of 92 implants were evaluated. No fixture or abutment fractures were reported. No abutment unscrewing was reported. Four framework fractures occurred after three, four, six, and seven years of function. The overall success rate of the rehabilitation was 82.6%. Mucositis was observed in eight patients and 13 implants. No peri-implantitis was recorded. A 0.55 mm difference of PPD and 0.74 mm of MBL was recorded after seven years (p < 0.001). The present implant-supported conometric retention system proved to be effective in giving fixed retention to a CP supported by four implants. Biological complications were easily detected and treated. An adequate metal framework should be provided to the definitive restoration to avoid fractures in the long term. [ABSTRACT FROM AUTHOR]