Search

Dental implant abutments play an important role in the health and aesthetics of soft and hard tissues around implants.To compare mechanical properties and marginal fit of prefabricated and customized dental implant abutments and provide references to evaluate the relationship between abutment choice and clinical indications.Titanium abutments were randomly divided into prefabricated and customized abutments. Static and dynamic loads were applied according to ISO14801:2016. Mechanical properties, including fracture strength, fatigue strength, rotational torque value, and torque loss rate, were measured. The biological properties of the implant abutments were assessed using an internal marginal fit. The samples were sliced, and the internal marginal fit was examined using a scanning electron microscope before and after cyclic loading. The length of the tight contact was calculated at the level of the conical connection, lower internal connection, and screw threads. Microleakage was evaluated by immersing the samples in 1% methylene blue and measuring the absorbance.The fracture strengths of the prefabricated abutments were greater than those of the customized abutments before and after cyclic loading. The average fatigue strengths of the prefabricated and customized abutments were 350 and 300 N, respectively. The removal torque loss of the customized abutments was significantly greater than that of the prefabricated abutments. Significant differences were found in conical connection before loading, while the screw threads showed substantial differences between the two groups after loading. Microleakage in the customized abutments was significantly higher than that in the prefabricated abutments before and after loading.Prefabricated abutments showed superior mechanical and biological properties compared with customized abutments in vitro, suggesting a greater risk of mechanical and biological complications occurring with the use of customized abutments. This study provides a reference for the clinical selection of implant abutments.

Objectives The objective of this study was to analyze the impact of the abutment width on early marginal bone loss (MBL). Material and Methods A balanced, randomized, double-blind clinical trial with two parallel experimental arms was conducted without a control group. The arms were “cylindrical” abutment and “concave” abutment. Eighty hexagonal internal connection implants, each with a diameter of 4 × 10 mm, were placed in healed mature bone. The main variable was the peri-implant tissue stability, which was measured as MBL at 8 weeks and 6 months. Results The final sample consisted of 77 implants that were placed in 25 patients. 38 (49.4%) were placed using the cylindrical abutment, and the other 39 (50.6%) were placed using the concave abutment. The early global MBL of −0.6 ± 0.7 mm in the cylindrical abutment group was significantly higher than it was in the concave abutment group, in which the early global MBL was −0.4 ± 0.6 mm (p = .030). The estimated effect size (ES) was negative for the cylindrical abutment (ES = −1.3730, CI −2.5919 to −0.1327; t-value = −2.4893; p = .0139), therefore implying a loss of mean bone level, and it was positive for the concave abutment (ES = 2.8231; CI: 1.4379 to 4.2083; t-value = 4.0957; p = .0002), therefore implying an increase in the average bone level. Conclusions The concave abutments presented significantly less early MBL at 6 months post-loading than classical cylindrical abutments did.

OBJECTIVE: To compare 5-year biological, technical, aesthetic, and patient-reported outcomes of single-tooth implant-supported all-ceramic versus metal-ceramic restorations.MATERIALS AND METHODS: Thirty patients with 63 premolar agenesis participated in the 5-year follow-up. The prosthetic treatment on single-tooth implants was randomly assigned to all-ceramic crowns on zirconia abutments (AC = 31) or metal-ceramic crowns on metal abutments (MC = 32). All patients were recalled to clinical examinations at baseline, 1, 3, and 5 years after prosthetic treatments. Biological, technical, and aesthetic outcomes including complications were clinically and radiographically registered. The patient-reported outcomes were recorded using OHIP-49 questionnaire before treatment and at each follow-up examination.RESULTS: At the 5-year examination, the survival rate was 100% for implants and 100% for AC and 97% for MC crowns and abutments. The marginal bone loss after 5 years was minor and not significantly different (p = .056) between AC (mean: 0.3, SD: 1.1) and MC (mean: -0.1, SD: 0.4) restorations. The success rate of the implants based on marginal bone loss was 77.4% for AC- and 93.7% for MC restorations. The marginal adaptation was significantly better for MC than for AC restorations (p = .025). The aesthetic outcomes and patient-reported outcomes between AC and MC restorations were not significantly different.CONCLUSIONS: The biological, aesthetic and patient-reported outcomes for implant-supported AC and MC restorations were successful and with no significant difference after 5-years. The marginal adaptation of the MC crowns cemented on titanium abutments showed a significantly better fit than restorations based on zirconia crowns cemented on zirconia abutments.

To assess the effect of implant abutment material and soft tissue thickness on the peri-implant soft tissue color using spectrophotometry and to evaluate gingival esthetics and patient satisfaction with three different abutments.Twenty-five patients with a missing maxillary tooth in the esthetic area received an endosseous implant using a two-stage protocol. Gray titanium, pink anodized titanium, and hybrid zirconia custom abutments were fabricated for each participant and inserted for one week with a cross-over design in a randomized manner. Color measurements were made using a spectrophotometer comparing midfacial peri-implant soft tissue and marginal gingiva of the contralateral tooth. CIE Lab color scale was used following the formula: ΔE = [(∆L)Abutment material type significantly affected the ΔΕ values of the peri-implant mucosa when compared to the contralateral teeth. At baseline, the highest ΔΕ means ± standard deviation (SD) values were obtained with gray titanium (11.25 ± 2.98), followed by pink anodized titanium (9.90 ± 2.51), and zirconia abutments (6.46 ± 1.43). Differences were statistically significant irrespective of soft tissue thickness. The highest PES values were obtained with zirconia abutments (10.88 ± 0.88), followed by pink anodized titanium (10.12 ± 1.13) and the lowest with gray titanium (9.68 ± 1.41). PES differences were significant only for the thin soft tissue group. Regarding patient satisfaction, VAS scores for the pink anodized and zirconia hybrid abutment groups were higher than the gray titanium group for each question.The color difference between soft tissues around teeth and implants was significant in all groups regardless of tissue thickness. The hybrid zirconia abutments resulted in the least color difference, followed by pink anodized and gray titanium. Significantly different PES values were recorded only for the thin tissue group. There was no significant difference in patient satisfaction between zirconia and pink anodized abutments at the 1-year follow up. Pink anodized abutments represent a good esthetic alternative to zirconia hybrid abutments especially in mechanically challenging situations.

To compare screw-retained and cemented all-ceramic implant-supported single crowns regarding biological and technical outcomes over a 5-year observation period.In 44 patients, 44 two-piece dental implants were placed in single-tooth gaps in the esthetic zone. Patients randomly received a screw-retained (SR) or cemented (CR) all-ceramic single crown and were then re-examined annually up to 5 years. Outcome measures included: clinical, biological, technical, and radiographic parameters. Data were statistically analyzed with Wilcoxon-Mann-Whitney, Wilcoxon, and Fisher's exact tests.During the observation period, three patients (6.8%) were loss to follow-up. Eight restorations (18.2%, CI (8.2%, 32.7%)) were lost due to technical (6 patients, 13.6% (CI (5.2%, 27.4%)), 2 CR and 4 SR group, intergroup p = .673; implants still present) or biological complications (2 patients, 4.5% (CI (0.6%, 16.5%)), only CR group, intergroup p = .201, both implants lost). This resulted in a survival rate of 81.2% (CI (65.9%, 90.1%)) on the restorative level (18 SR; 15 CR, 3 lost to follow-up). At the 5-year follow-up, the median marginal bone levels were located slightly apical relative to the implant shoulder with 0.4 mm (0.5; 0.3) (SR) and 0.4 mm (0.8; 0.3) (CR) (intergroup p = .582). Cemented restorations demonstrated a significantly higher biological complication rate (36.8%, SR: 0.0%; intergroup p = .0022), as well as a significantly higher overall complication rate (68.4%, SR: 22.7%, intergroup p = .0049). All other outcomes did not differ significantly between the two groups (p .05).All-ceramic single-tooth restorations on two-piece dental implants resulted in a relatively low survival rate. Cemented restorations were associated with a higher biological and overall complication rate than screw-retained restorations.

To evaluate the long-term integrity of implant-abutment complexes in implant systems with two internal conical angles.12,538 bone-level implants of two systems placed between January 2012 and December 2018 were retrospectively analyzed. Cumulative abutment/implant fracture rates in systems with larger (LA, 7.5°) and smaller (SA, 5.7°) internal conical angles were estimated using the Kaplan-Meier analysis and compared between groups. The association between implant systems and jammed abutment retrievability was evaluated by multivariable generalized estimating equation logistic regression modeling.For LA, the 8-year cumulative incident rate was 0.10% (95% confidence interval (CI): 0-0.24%) for implant fracture and 0.26% (95% CI: 0.11%-0.41%) for abutment fracture, demonstrating a significant difference in gender (p = .03), implant diameter (p = .01), jaw (p = .006), and antagonist tooth (p .001). For SA, the 8-year cumulative incident rate was 0.38% (95% CI: 0-0.79%) for implant fracture and 2.62% (95% CI: 0.05%-5.13%) for abutment fracture, which was influenced by implant diameter (p .001) and site (p = .03). The cumulative implant/abutment fracture rate was lower for LA implants, particularly for LA implant-supported single crowns (SCs) (p .05). The abutment-retrieval success rate was 92.9% for LA and 57.1% for SA (p = .055).LA implants exhibited a lower incidence of fracture in abutment-implant complexes and a relatively higher retrievability success rate for jammed abutments.

To compare cemented and screw-retained one-piece zirconia-based restorations in terms of clinical, radiographic, and technical outcomes 5 years after insertion.Thirty-four patients with single-tooth implants were randomly restored with either a cemented lithium disilicate crown on a one-piece customized zirconia abutment (CEM, 17 patients) or a screw-retained crown based on a directly veneered one-piece customized zirconia abutment (SCREW, 16 patients). All patients were recalled for a baseline examination (7-10 days after crown insertion) and then annually up to 5 years. The following outcomes were assessed: marginal bone level (changes), technical, and clinical (bleeding on probing, plaque control record, probing depth, and keratinized tissue) parameters. The Mann-Whitney U-test was used to assess differences between the two groups.At 5 years, 26 patients (13 in each group) were re-examined. The survival rates on the implant and restorative levels were 100% and 82.4% (equally for both groups), respectively. At 5 years, the median marginal bone level was located at -0.15 mm (IQR: -0.89 mm; 0.27 mm) (CEM) and -0.26 mm (IQR: -0.38 mm; 0.01 mm) (SCREW) below the implant shoulder (intergroup p = .9598). The median changes between baseline and the 5-year follow-up amounted to -0.23 mm (CEM; intragroup p = .0002) and -0.15 mm (SCREW; intragroup p = .1465) (intergroup p = .1690). The overall technical complication rate at 5 years was 15.4% (CEM) and 15.4% (SCREW) (intergroup p = 1.00). Clinical parameters remained stable over time (baseline to 5 years).At 5 years, screw-retained and cemented restorations rendered largely the same clinical, technical, and radiographic outcomes. Technical complications were frequent in both groups.

PURPOSE: To assess the clinical, radiographic, and patient-reported outcome measures, including the success of screw-retained monolithic zirconia implant-supported restorations with CAD/CAM titanium abutments in the posterior region during a 1-year follow-up.METHODS: In a prospective case series, 50 molar sites in the posterior region of 46 patients with a minimum age of 18 years and sufficient bone volume and anatomical conditions for placing an implant (≥8 mm) and an anatomical restoration were included. Parallel-walled implants with a conical connection were inserted in a two-stage surgical procedure. Implant uncovering and healing abutment placement occurred 12 weeks after insertion. Two weeks after mucosa healing, a screw-retained monolithic zirconia restoration with a CAD/CAM titanium abutment was placed. Clinical, radiographic, and patient-reported outcome measures were collected at baseline before implant placement and then during the 1 month and 1 year follow-ups.RESULTS: At the 1 year follow-up, 49 restorations could be evaluated. The plaque accumulation, presence of calculus, bleeding tendency and peri-implant inflammation indices were low, representing healthy peri-implant conditions. The mean marginal bone level change between the 1 month and the 1 year follow-up was -0.17 ± 0.46 mm. The mean patient satisfaction was high. The restoration success was, according to the modified USPHS criteria, 95.9%.CONCLUSION: Monolithic zirconia implant-supported restorations with CAD/CAM titanium abutments have very good clinical, radiographic and patient-reported outcomes after 1 year in function.

PURPOSE The optimal abutment material and design for an angled implant-abutment connection in the esthetic zone is unclear. The purpose of this finite element analysis (FEA) study was to compare different abutment models by evaluating the stress values in the implant components and strain values on the simulated bone around an anterior maxillary implant with different angled abutment models and loading conditions. MATERIALS AND METHODS One O3.5×12-mm implant was placed in 3D FEA models representing the anterior left lateral segment of the maxilla. Three different contemporary implant models were created with 17- or 25-degree angled abutments (Ti base abutment, zirconia abutment, and titanium abutment) and 3D-modeled. The implant abutment model was an angled Ti base abutment (TIB), an angled zirconia abutment (ZIR), or an angled titanium abutment (TIT). Vertical and oblique loads of 100 N for the central incisors were applied as boundary conditions to the cingulum area and incisal area in a nonlinear FEA. RESULTS The TIB model resulted in reduced stress conditions. According to the von Mises stresses occurring on the screw, abutment, crown, and implant, especially under oblique loads, the TIB model was exposed to less stress than the ZIR or TIT models. Strain values in simulated cortical and trabecular bones were obtained lower in the TIB model. CONCLUSIONS When a standard implant was placed in the esthetic zone at an increased angle, the implants, abutments, and screws had more unfavorable stress levels; therefore, using a Ti-base abutment may reduce stress. The amount of contact surface of the implant with the simulated cortical bone is also an important factor affecting stress and strain. This article is protected by copyright. All rights reserved.

AIM To evaluate 1-year bone-level changes around subcrestal platform-switching implants with 1 or 3 mm definitive abutments. The influence of mucosal thickness on bone-level alterations was further analysed. MATERIALS AND METHODS Implants were placed in the posterior sextants and positioned 1.5 mm subcrestally with an abutment of 1 or 3 mm height. Final restorations were delivered after 16 weeks. Radiographic measurements of inter-proximal bone level were the primary outcome and were adjusted by vertical mucosal thickness. Peri-implant clinical conditions and resonance frequency analysis were also compared. RESULTS A total of 65 subjects with 99 implants were analysed. The overall 1-year implant survival rate between the 1- and 3-mm groups was 96.4% and 94.4%, respectively. Statistically significant lower inter-proximal marginal bone-level changes were observed in the 3-mm group (1 mm: -0.17 ± 0.02 mm at mesial and -0.21 ± 0.02 mm distal; 3 mm: -0.03 ± 0.02 mm at mesial and -0.03 ± 0.02 mm and distal; mesial: p = .001; distal: p

Objective to determine the presence of marginal bacterial microfiltration in the IAI in different implant/abutment systems, in vitro. Material and methods Fifty‐six implants from seven different brand names, 4 with cone and 3 with straight connections were used, implant and abutment were connected using the Ncm tightening as indicated by each of the manufacturers and then were sealed. The samples were subjected occlusal load and thermal cycling, a first sample of each group was observed by micro CT and in a second sample (both samples randomly selected) length of connection was measured, while the rest of the samples were mounted on devices according to the bacterial microfiltration model with Porphyromonas gingivalis. Results Two of the conical connection system groups did not present bacterial microfiltration, one of the three straight connection groups only microfiltered in one sample, while the other two conical as well as the two straight connection samples showed different and important levels of bacterial microfiltration, all groups presented a direct relationship between the implant‐abutment adjustment determined by micro‐CT and bacterial microfiltration levels, not related to the connection length. Conclusion: Only two conical connection systems presented no bacterial microfiltration.

BACKGROUND Limited information is available regarding the removal torque values (RTVs) of screws of different abutment materials when used with different implants. PURPOSE To evaluate the effect of implant type and abutment material (zirconia; Zir and titanium; Ti) on the RTVs of abutment screws after cyclic loading. MATERIALS AND METHODS Internal conical connection implants (CC, OsseoSpeed TX) and modified internal conical connection implants (MCC, OsseoSpeed EV) (n = 10) were clamped in resin dies. Zir and Ti (N = 20) custom abutments were tightened to implants (20 Ncm for CC and 25 Ncm for MCC) as specified by their manufacturers. The abutments were cyclically loaded by using a sequentially increased loading protocol; 2-million cycles under 100 N, 3-million cycles under 200 N, and 2-million cycles under 300 N loads with 2 Hz. After 7 million cycles, RTVs (Ncm) were measured by using a torque gauge. The data were analyzed with ANOVA by using the restricted maximum likelihood estimation method. Tukey-Kramer adjustment was used for any significant interaction of implant-abutment pairs (α = 0.05). RESULTS Two CC implants, 1 with Ti and 1 with Zir abutment, fractured during cyclic loading (under 300 N loads within the 6th and 7th million cycles) and discarded for statistical analysis. Only implant type had a significant effect on RTVs (p

Objectives To analyse the long-term effect of plaque formation on implant abutments with an antibacterial coating and the ensuing host response in peri-implant tissues. Materials and methods Four implants were installed in each mandibular premolar region following tooth extraction in six dogs. Three months later, two test abutments with a titanium-bismuth-gallium (Ti-Bi-Ga) coating and two control titanium abutments were connected to the implants on each side of the mandible. After 2 months, ligatures were placed around the implants in one side of the mandible and plaque formation was allowed until the end of the experiment. The ligatures were removed after 4 weeks. Radiographs and microbiological samples were obtained from each implant site during the plaque formation period. Biopsies were obtained 8 months after abutment connection and prepared for histological analysis. Results The analysis did not reveal any statistically significant differences in bone loss, bacterial growth and size of inflammatory lesions between implant units with and without the Ti-Bi-Ga coating. Implant sites exposed to the short period of ligature-induced breakdown demonstrated more pronounced bone loss and bacterial growth than non-ligature sites. Conclusions It is suggested that a Ti-Bi-Ga coating does not prevent biofilm formation on the implant device and does not influence the ensuing host response in the adjacent peri-implant mucosa.

Objective Emergence profile design is important for stable peri-implant tissues and esthetically pleasing results with dental implant restorations, influenced by factors, such as, implant position and surrounding soft tissues. Different aspects of the emergence profile have been described, but detailed explanations of the different zones and corresponding designs are missing. This article describes the esthetic biological contour concept (EBC), differentiating important areas of the emergence profile and recommending particular designs for those zones. Overview The EBC concept considers specific parameters for proper design of the emergence profile of implant-supported restorations. Understanding the different zones of the emergence profile and their relation to factors like implant position, implant design, and soft tissue thickness is key. The suggested guidelines are geared toward providing more stable and esthetic results when restoring dental implants in the esthetic zone. Conclusions Each of the zones described in the EBC concept have a specific function in the design of the emergence profile. Understanding the importance and specific design features of the EBC zones facilitates esthetic and biologically sound treatment outcomes with interim and definitive implant restorations. Clinical significance Proper emergence profile design supports esthetic outcomes and provides favorable biological response to implant-supported restorations.

BACKGROUND Peri-implant tissue condition can result from prosthodontic, surgical and bacteriological factors. PURPOSE This study investigated the effects of prosthodontic factors on peri-implant tissue. MATERIALS AND METHODS Subjects were 140 patients with 310 implants from Osaka University Dental Hospital. Prosthodontic factors examined were the connection type, the suprastructure retention type, the material of the abutment and the mesiodistal and buccolingual prosthetic form of the superstructure as emergence angle. The objective variables were the modified bleeding index (mBI) and marginal bone level (MBL). Statistical analysis was used as a generalized estimation equation. RESULTS The taper joint had a significantly smaller MBL than the butt joint (P

Objectives The study purpose was to examine peri-implant bone alternations around osseointegrated implants caused solely by abutment screw preload stress using different tightening torque values. Materials and methods Twenty 20- to 22-week-old Japanese white rabbits received two implants each in right and left femurs. Implants were randomly assigned to one of three tightening torque groups or the control (Cont) group. After 8 weeks, 35 Ncm torque was delivered to abutment screws in the recommended torque (RT) group (n = 16). Other screws received 70 Ncm torque as the high torque (HT) group (n = 16). Temporary tightening (TT) groups (n = 8) received only 70 Ncm torque without preload stress as screws were untightened immediately. Cont group (n = 40) remained in situ. Animals were euthanized at 4, 6, 8, and 10 weeks after torque application. Micro-CT images were then taken, and undecalcified ground sections were stained with toluidine blue. Results Cross-sections of cortical bone showed remodeling activities adjacent to the implant in all groups. While bone marrow spaces appearance was relatively small in Cont and TT groups, RT and HT groups showed large bone marrow spaces and extensive remodeling activity. Bone-to-implant contact was significantly less in RT and HT groups compared with Cont and TT groups at different time points (p ˂ .05). Furthermore, RT and HT groups showed significantly less bone volume and area (p ˂ .05). Conclusion Results suggested that preload stress without any occlusal loading might negatively affect peri-implant bone stability and initiate bone remodeling. This could alter bone mechanical properties, subsequently influencing long-term implant success.

BACKGROUND Soft tissue reaction to dental implant abutments influences the sustainability of restoration. Several abutment materials, such as titanium and gold alloy, have been introduced for strength and esthetic solutions. Zirconia and titanium-base abutments have also become popular in recent years due to high esthetic demands. PURPOSE To investigate the immune cell infiltration into the soft tissue in response to different abutment materials. MATERIALS AND METHODS Twenty dental implants were placed in the posterior regions of 17 patients. Titanium, zirconia, gold alloy, and titanium-base were randomly selected for each patient on the day of surgery. After 8 weeks of healing, the abutments were removed along with 1 mm of peri-implant soft tissue. Immunohistochemical assessment was performed using labeled streptavidin-biotin to identify T cells, B cells, macrophages, plasma cells, and microvascular infiltration. RESULTS Gold alloy demonstrated an overall higher inflammatory cell infiltration and highest number of CD3+ , CD20+ , and CD 68+ cells (P value

Objectives To evaluate the influence of abutment disconnections and reconnections on peri-implant marginal bone loss. Material and methods Twenty-four participants received single-unit implants and were randomly assigned into one of the two groups: the definitive abutment group (DEF), in which the definitive abutments were connected at the same time as the implant was inserted; and as a control, the healing abutment group (HEA), in which the healing abutments were disconnected and reconnected three times, at 8, 10, and 12 weeks after surgery. Peri-implant marginal bone level was measured through radiographic follow-up performed immediately after the surgery (baseline), at 8 weeks and after 6, 12, and 24 months. Implant stability and peri-implant health were assessed by resonance frequency analysis and peri-implant probing, respectively. Results At the end of 2 years, the mean bone level was -0.18 ± 0.12 mm for the DEF group and -0.13 ± 0.13 mm for the HEA group, resulting in a cumulative bone loss of -0.61 ± 0.10 mm and -0.81 ± 0.15 mm, respectively, with no statistical difference between groups. Bone level changes showed statistically significant differences only between 0 and 2 months (DEF: -0.70 ± 0.12 mm; HEA: -0.36 ± 0.10 mm) and between 2 and 6 months (DEF: -0.11 ± 0.11 mm; HEA: -0.65 ± 0.14 mm). No differences were observed between the groups for implant stability, probing depth, and bleeding on probing. Conclusion Immediate connection of the prosthetic abutments did not reduce bone loss in comparison with three disconnections of the healing abutments.

PURPOSE The aim of this study was to assess the microbiological and clinical outcomes of implant-supported restorations on zirconia or titanium abutments after 3 years in function. MATERIALS AND METHODS Twenty two-part dental implants were placed in 20 healthy individuals in need of single-tooth replacement. Ceramic-based reconstructions were cemented in either zirconia or titanium abutments. Clinical, radiographic, and microbiological outcomes were examined at implant loading and then yearly up to 3 years post-loading. RESULTS Cumulative survival/success implant rates were 95% after 3 years. Mean total marginal bone loss was 0.76 ± 0.21 mm for zirconia and 0.99 ± 0.41 mm for titanium, with no significant differences (P > .05). Overall, titanium and zirconia abutments presented similar values of probing depth, gingival recession, and bleeding on probing over time (P

Fracture Resistance Of Single-Unit Implant-Supported Crowns: Effects Of Prosthetic Design And Restorative Material Fracture Resistance Of Single-Unit Implant-Supported Crowns: Effects Of Prosthetic Design And Restorative Material Fracture Resistance; İmplant; PEEK; Screw-Cement Crown. Fracture Resistance; İmplant; PEEK; Screw-Cement Crown. Purpose: To evaluate the fracture resistance and fracture patterns of single implant-supported crowns with different prosthetic designs and materials.Materials and Methods: One hundred and forty-four identical crowns were fab-ricated from zirconia-reinforced lithium silicate (ZLS), leucite-based (LGC), andlithium disilicate (LDS) glass-ceramics, reinforced composite (RC), translucent zir-conia (ZR), and ceramic-reinforced polyetheretherketone (P). These crowns weredivided into 3 subgroups according to restoration design: cementable crowns on aprefabricated titanium abutment, cement-retained crown on a zirconia-titanium baseabutment, and screw-cement crown (n = 8). After adhesive cementation, restorationswere subjected to thermal-cycling and loaded until fracture. The fracture patternswere evaluated under a stereomicroscope. Statistical analysis was performed by us-ing 2-way ANOVA/Bonferroni multiple comparison post hoc test (α = 0.05).Results: For each prosthetic design, ZR presented the highest fracture resistance(p ≤ 0.005). Other than the differences with ZLS and RC for screw-cement crowns(p > 0.05) and RC for crowns on zirconia-titanium base abutments (p > 0.05), LGCshowed the lowest fracture resistance. P endured higher loads than LDS (p < 0.001),except for the crowns on zirconia-titanium base abutments (p > 0.05). Cementablecrowns presented the highest fracture resistance (p < 0.001), other than LGC andLDS. The differences between LGC crowns (p > 0.05) or LDS crowns on prefab-ricated titanium and zirconia-titanium abutments were nonsignificant (p = 0.133).Fragmented crown fracture was predominant in most of the restorations. Screw andabutment fractures were observed in ZR screw-cement crowns, and all P crowns wereseparated from the abutments.Conclusions: Restorative material and restoration design affect the fracture resis-tance and fracture pattern of implant-supported single-unit restorations. Cliniciansmay restore single-unit implants in premolar sites with the materials and prostheticdesigns tested in the present study.

Background Immediate implants have shown risks of esthetic complications. The hypothesis was that a customized healing abutment could improve the peri-implant tissue healing. Purpose To evaluate and compare the soft and hard tissue healing around immediate implants that received bone grafting and a customized vs a standard healing abutment. Materials and methods Patients, who required tooth extraction and who received an immediate implant (with an alloplastic graft material) were randomly assigned to a customized or a standard healing abutment group. Clinical and radiographic examinations were taken at baseline, at 4 and 12 months. Results Twenty-five patients out of 61 were excluded from the study because unsuitable for immediate implantation. In total, 36 patients were randomized in the two groups. There were 17 females and 19 males (age range 23-77). No prosthetic or implant failure was registered during the study period. The Papilla Index was significantly higher in the customized than in the standard group at 4 and 12 months (P = .0002). The bone loss at mesial sites was significantly higher in the control than in the test group (P = .0014). Conclusion The customized healing abutment group showed the most favorable outcomes (in terms of PI and MBL) in case of immediate implant that received a peri-implant bone grafting procedure.

Background Implant‐supported restorations in the posterior region are subjected to various complications that could be prevented by changing either the design or the material. Purpose The aim of this prospective case series study was to evaluate full‐zirconia implant‐supported restorations with angulated screw channel abutments in the molar region of the maxilla and mandible and their effect on hard and soft peri‐implant tissues, during a 1‐year follow‐up period. Materials and Methods Thirty consecutive patients with a single missing molar, sufficient bone height, and implant site free of infection were included. Each patient was to receive a parallel‐walled implant with conical connection according to a two‐staged surgical protocol. After 3 months, a full‐contour screw‐retained zirconia restoration with angulated screw channel abutment was provided. Clinical and radiographic examinations were performed 1 and 12 months after placement of the restoration. Patients' satisfaction was scored prior to treatment and after 12 months with the restoration in function. Primary outcome measure was success of the restoration. Results All patients could be evaluated after 12 months. Success of the restorations was 100%. From loading to the 12‐month follow‐up, the mean marginal bone loss was 0.16 mm (SD: 0.26). Mean scores for plaque, calculus, peri‐implant mucosa, bleeding, and pocket probing depth were low, depicting healthy peri‐implant conditions. Patients' satisfaction was high and had improved after treatment. Conclusion Full‐contour zirconia implant‐supported restorations with angulated screw channel abutments in the molar region have an excellent clinical performance after 1 year of function.

Objective This study investigated the effects of abutment screw withdrawal after conical abutment settlement on the stability of the implant-abutment connection. Materials and methods Twenty implants of a conical connection system were used. Two two-piece abutment designs were used: cone only (n = 10; NI) and cone plus octagonal index design (n = 10; I); for each design, five samples were used with (S) and without (NS) abutment screw withdrawal before a cyclic test. Finally, four groups, namely Gr S(NI), Gr S(I), Gr NS(NI), and Gr NS(I), were included. The cyclic test included cyclic loading of 20-200 N, 30°, and 4-mm off-axis to implant axis at 10 Hz for 106 cycles, simulating a clinical time interval of 40 months. The fatigue cycles were recorded. The axial displacement of the conical abutments during abutment settlement, screw withdrawal, and cyclic loading were measured. Abutment morphology was examined through scanning electron microscopy (SEM). Results Only Gr NS(NI) failed the test, indicating that without the index design and abutment screw withdrawal, and connection stability seriously deteriorated. Gr NS(I) exhibited significantly higher axial displacement into the implant after abutment settlement than did Gr NS(NI). It also exhibited continuous axial displacement into the implant after cyclic loading. SEM after cyclic testing in Gr NS(I) revealed marked burnishing on lateral edges of the index, indicating that the index design provides an antitorsional ability. Conclusion Although this study has few limitations, abutment screw withdrawal is feasible in this conical implant-abutment connection system with index design.

Background Little is known regarding the interaction of dental implant surface nanotubes and oral soft and hard tissues. The purpose of this study was to evaluate both histologically and radiographically the qualitative and quantitative effects of dental implant surface nanotubes on hard and soft tissue in a canine model. Methods Three subgroups consisting of a combination of test and control implants and abutments (Group A: control implant/control abutment, Group B: control implant/test abutment: Group C: test implant/test abutment) were placed in edentulous mandibles of six large-breed canines. Implants and abutments were placed on one side at baseline, and on the opposite side of the mandible at week 10; sacrifice occurred at week 12. Quantitative and qualitative analyses were used to measure newly formed hard and soft tissues histologically and radiographically. Results The mean radiographic change in marginal bone level from weeks 0 to 12 between implant groups was not statistically significant (P > 0.05). Mean soft tissue contact (junctional epithelium + connective tissue) for Groups A, B, and C were 2.29, 2.33, and 2.31 mm, respectively, with no statistically significant difference (P > 0.05) between the groups. All connective tissue fibers were oriented parallel to the abutment regardless of surface treatment. Conclusions The findings of this study suggest that healing of hard and soft tissues around implants and abutments is similar when comparing grit-blasted surfaces to machined, turned surfaces with nanotubes. Both resulted in similar soft tissue contact values, as well as connective tissue fiber orientation.

Objective This retrospective analysis was designed to compare the survival and success of dental implants in solely implant-supported, double crown-retained removable dentures (DCRDs) and combined tooth-implant-supported DCRDs, due to a lack of data on the latter. Material and methods From 2002, patients were consecutively admitted for treatment at the Department of Prosthodontics, University of Heidelberg. Surgical and prosthodontic treatment and scheduled and unscheduled visits were recorded on standardized documentation forms. Kaplan-Meier analysis was used to estimate success (survival without major complications). Cox regression was applied to assess risk factors. Results From this clinical study, 139 DCRDs on 412 implants and 239 teeth met the inclusion criteria. Fifty-three dentures were implant-supported (213 implants). Eighty-six were supported by teeth and implants. The DCRDs were placed in 126 patients. After an observation period of up to 11.2 years (median: 4.2 years), total implant survival was 99.5% for tooth-implant-supported DCRDs and 93.4% for implant-supported ones. The estimated cumulative success was 97.2% (standard error/SE ± 1.2%) and 85.9% (SE ± 2.4%) at five years, respectively. Complications included implant or tooth loss, peri-implantitis, apical periodontitis and tooth fracture. In terms of abutments, results from multiple Cox regression revealed lower failure rates in tooth-implant-supported dentures (p = .04). No other risk factors were identified. Conclusions Within the limitations of this study, survival and success are high for both treatment options. Combining teeth and implants in one DCRD might have a positive effect on the prognosis of the implant and the survival of remaining teeth.

Purpose To evaluate the long-term implant survival rate of titanium implants with zirconia abutments, and the effects of implants with zirconia abutments on marginal bone loss (MBL) and pocket probing depth (PPD) compared with all-titanium implants. Materials and methods The searched electronic database included the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and the Chinese Biomedical Literature Database. Two types of studies were included: clinical studies reporting the survival rate of titanium implants with zirconia abutments with at least a mean/median 5-year follow-up, and clinical trials reporting the effects of implants with zirconia abutments on MBL and PPD compared with all-titanium implants. Two reviewers screened and selected the records, assessed quality, and extracted data of included studies independently. Results This review included 16 studies from 18 publications. None of the comparative studies was assessed at a low risk of bias. The overall implant survival rate of implants with zirconia abutments was estimated to be 96% (confidence intervals [CIs] [94%, 98%], I2 = 0%). For the comparison between implants with zirconia abutments and all-titanium implants, the results significantly favored implants with zirconia abutments (for MBL, mean difference [MD] = -0.09, CIs [-0.17, 0.00], p = 0.05, I2 = 40%; for PPD, MD = -0.18, CIs [-0.32, -0.05], p = 0.008, I2 = 0%). Zirconia abutments were favored more when the prosthesis was an implant-supported overdenture rather than a single crown. Conclusions Implants with zirconia abutments may have an acceptable performance on peri-implant health compared with all-titanium implants; however, the implant survival rate of implants with zirconia abutments is slightly lower than all-titanium implants in the long-term follow-up. Additional studies are needed to explain this dichotomy.

Objectives Two-part abutments consist of titanium base and ceramic coping. Their long-term success is largely determined by the mechanical stability. The aim of the present study was to investigate the retention forces of two-part implant abutments. The study included zirconia and lithium disilicate ceramics copings, with different surface treatments and resin-based luting agents. Material and methods The analysis of retention forces was based on a total of 70 test specimens. Seven surface modifications and three resin-based luting agents were employed for the bonding of components in the seven groups (n = 70). All surfaces of titanium bases-except for a control-were pretreated with aluminum oxide blasting, either alone or in combination with surface activating primers. Surfaces of ceramic copings were also treated mechanically by sandblasting, either alone or with acid etching or different primers. All specimens underwent thermal aging (104 cycles, 5°C/55°C). The retention forces between the two parts were measured with a pull-off test. The results were analyzed by two-way ANOVA statistics. Fracture patterns were evaluated by light and scanning electron microscopy. Results No mechanical pretreatment of the titanium (group 2) base resulted in the lowest retention. The combination with Monobond plus leads to the highest pull-off forces for both ceramic materials. Conclusions Surface modifications and resin-based agents influence the retention of components of two-part abutments. Lithium disilicate ceramic copings reached comparable results of retention to the typically used zirconia copings.

PURPOSE To determine the accuracy of a digital manufacturing method for dental implant restorations on stock abutments using intraoral scanners and prefabricated stock-abutment libraries. MATERIALS AND METHODS Two dental implants with internal hexagonal connections were placed in the mandibular second premolar and second molar areas of a partially edentulous dentoform model; stock abutments with a diameter of 5 mm, abutment height of 5.5 mm, and gingival cuff height of 2 mm were connected. The study model was scanned 10 times using a reference tabletop scanner and 5 types of intraoral scanners (IOSs). The data collected by 5 types of IOSs were divided into 3 groups, based on the type and matching of stock abutment library data: no library, optical library, and contact library groups. A total of 160 data files were analyzed, including reference data. The resulting data were used to evaluate trueness and precision. RESULTS Trueness and precision values in the group in which library data of the stock abutment were not used were 42.0 to 76.3 µm and 30.5 to 99.7 µm; corresponding values when the library data using an optical scanner were matched were 51.2 to 73.4 µm and 26.3 to 62.8 µm, and those when contact scanner library data were used were 30.1 to 62.4 µm and 15.5 to 55.9 µm. Thus, the accuracy of the contact library group was significantly higher than the accuracies of the no library (p < 0.001) and optical library groups (p < 0.001). CONCLUSION The application of prefabricated library data of stock abutments using a contact scanner improved the accuracy of scan data. Scan accuracy of the stock abutments differed significantly based on the type of scanner.

Objective The unavoidable extraction of teeth in the esthetic area can be overcome through different treatment modalities. Recently, immediate implants appeared as a minimally invasive approach to resolving these cases; however, immediate implant loading is not always possible or indicated. In these cases, an innovative approach through customized healing abutments could be used to preserve the soft tissue contour, eliminating the need for reopening surgery and the use of provisional restorations to condition the mucosal contour. Clinical considerations The present cases describe a simplified chairside approach to use customized healing abutments for immediate implants placed after tooth extraction in the anterior and posterior areas in order to maintain the soft tissue contours while reducing the clinical steps until delivering the final restorations. Conclusions This technique seems to be effective to guide the soft tissue healing around dental implants allowing a natural emergence profile with implant-supported restorations, reducing the number of treatment steps. Clinical significance The use of customized healing abutments prepares soft tissue for the prosthetic stage preserving its contours and eliminating the need for reopening surgery.

Objectives The aim was to evaluate the peri-implant tissue levels over a 1-year period for implants connected to either convex or concave final abutments at the time of implant placement. Materials and methods In this randomized, double masked, controlled clinical study, twenty-eight patients with one missing maxillary premolar were allocated to receive one single implant with abutment of either convex (CX Group) or concave (CV Group) emergence shape. A block randomization sequence was used to allocate treatments. Opaque sealed randomization envelopes were used for allocation concealment. All implants received final abutments and interim crowns at implant placement and permanent crowns following 3 months. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), and 12 months following implant placement (FU-1). Results One patient from the CX Group (n = 13) dropped out from the study and for one patient from CV Group (n = 13), the implant failed to integrate. The mean change in peri-implant buccal mucosa position (MP) from IP to FU-1 was -0.76 ± 0.72 mm for CX Group and -0.69 ± 0.89 mm for CV Group (p = 0.8). The amount of bone remodeling above the implant platform from IP to FU-1 was -0.66 ± 0.46 mm for the CX Group and -0.24 ± 0.25 mm for the CV Group (p = 0.007). Buccal bone thickness was significantly correlated with the amount of buccal MP change from IP to FU-1 (r = 0.4, p = 0.038). Conclusion The study failed to support the hypothesis that abutment macro-design has an effect on peri-implant mucosa margin position changes over time.

PURPOSE Removal of cement-retained implant crowns can be difficult and often requires sectioning of the prosthesis by rotary instruments. This study aimed to measure how much time is required in crown removal and the temperature changes when erbium-doped yttrium aluminum garnet (Er:YAG) laser was used to retrieve lithium disilicate crowns from titanium implant abutments luted with composite resin (CR) cement and resin-modified glass ionomer (RMGI). MATERIALS AND METHODS Forty identical lithium disilicate crowns were fabricated for prefabricated titanium abutments. CR and RMGI cements were used to lute the crowns, 20 specimens for each cement. Specimens were kept in 100% humidity for 48 hours. Er:YAG laser was then used to facilitate the crown retrieval. The retrieval time was recorded. The temperature changes at the abutment level for each type of cement were recorded during irradiation of 10 specimens for each type of cement from 1 to 10 minutes. Data were analyzed using t-test (ɑ = 0.01) and paired t-test (ɑ = 0.05). The surfaces of the crown and the abutment were further examined using scanning electron microscopy (SEM). RESULTS The average times of crown removal from titanium abutments were 196.5 seconds for CR and 97.5 seconds for RMGI groups with statistical significance (p < 0.001). The temperatures measured from 1 to 10 minutes of irradiation ranged from 18° to 20.8° for CR and 18° to 23° for RMGI at the abutment surface, and 22.1° to 24.6° for CR and 22° to 24.8° for RMGI at the crown surface. No statistical differences were observed between temperature changes at the abutment or the crown for each cement (p = 0.63); however, there was a statistically significant difference between the temperatures at the abutment and crown for both cements (p < 0.001). SEM examination showed no visible damage caused by treatment with Er:YAG laser. CONCLUSIONS It is faster to remove lithium disilicate crowns from titanium implant abutments when luted with RMGI compared to CR cement. The temperature rise was higher in the crown compared to the abutment. The type of cement had no effects on temperature changes. Heat generated from Er:YAG irradiation does not appear to be high enough to have any adverse effect on implant osseointegration.

The digital workflow presented here allows for fabrication and placement of a definitive custom abutment at the time of tooth extraction and guided immediate implant placement, thus preserving soft tissue anatomy. Since abutment design was based on the shape of the original tooth, it represented a de facto emergence-analog that provided ideal soft tissue support. The approach of superposing and merging of custom abutment design data with data captured intraorally after abutment placement enabled a digital impression without gingival displacement and associated trauma. The generated data facilitated the fabrication of a precisely fitting restoration concurrent with the implant healing period.

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 (TM)) and 23 CAD/CAM-customized (Atlantis (TM)) 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 alpha = 0.05. Results The fracture loads of the stock zirconia abutments were significantly (p

Background It is well established that electrochemical anodization of implant surfaces contributes to osseointegration and long-term implant survival. Few studies have investigated its effect on soft tissue healing. Purpose To evaluate the safety and efficacy of a novel abutment surface prepared by electrochemical oxidation compared to commercially available machined titanium abutments. Materials and methods Twelve 16-19 months-old, Yucatan mini-pigs received three dental implants in each mandibular jaw quadrant. Each side was randomized to receive either an anodized or a machined titanium abutment. Titanium healing caps were placed on both abutments. Animals were euthanized at 6 and 13 weeks. Radiographic and histological analyses were performed. Results No significant differences were observed histologically between groups in regard to inflammation, epithelium length, mucosal height, bone-to-implant contact, or bone density for any time point. Radiographically, crestal bone level change from baseline to 6 weeks was significantly lower for anodized than machined abutments (P = 0.046); no significant differences were observed at 13 weeks (P = 0.12). Conclusions The novel anodized abutment showed a comparable effect on soft and hard tissue healing/remodeling and inflammation reaction to standard titanium abutments. Clinical studies should confirm these findings and explore the positive radiographic results observed at the early time point.

Background A newly developed, anodized titanium oxide surface containing anatase has been reported to have antimicrobial properties that could reduce bacterial adherence to abutments. Purpose To investigate if abutments with the anodized surface improve healing and soft tissue health in a randomized controlled study. Materials and methods Test abutments with a nanostructured anodized surface were compared with control machined titanium abutments. In total, 35 subjects each received a pair of test and control abutments. The primary endpoint was reduction of biofilm formation at test abutments at the 6-week follow-up. Secondary endpoints included several soft tissue assessments. qPCR for gene markers was used to indirectly evaluate healing and soft tissue health. Results No significant differences in biofilm formation were observed between test and control abutments, but soft tissue bleeding upon abutment removal was significantly lower for test abutments compared with control abutments (P = 0.006) at 6 weeks. Keratinized mucosa height was significantly greater at test abutments compared with control abutments at the 6-week, 6-month, and 2-year follow-ups. Significant gene expression differences indicated differences in healing and tissue remodeling. Conclusions Abutments with an anodized and nanostructured surface compared with a conventional, machined titanium surface had no significant effect on bacterial colonization and proteolytic activity but were associated with better soft tissue outcomes such as a lower bleeding index at abutment removal and consistently greater height of keratinized mucosa throughout the 2-year follow-up, suggesting improved surface-dependent peri-implant healing and soft tissue health.

BACKGROUND Long-term success and patient satisfaction of dental implant systems can only be achieved by fulfilling clinical as well as biological needs related to maintenance, aesthetics, soft tissue sealing, and osseointegration, among others. Surface properties largely contribute to the biological and clinical performance of implants and abutments. PURPOSE To decipher the clinical and biological needs in implant dentistry. To address identified needs, next-generation dental implant and abutment surfaces are designed and characterized in vitro. MATERIALS AND METHODS Novel implant and abutment surface designs were produced and characterized using surface chemical analysis, surface topography analysis, scanning electron microscopy, contact-angle measurements, and cell-culture experiments. RESULTS The novel anodized implant surface was gradually anodized, increasing the surface roughness, surface enlargement, and oxide-layer thickness from platform to apex. The surface was phosphorus enriched, nonporous, and nanostructured at the collar, and showed micropores elsewhere. The novel anodized abutment surface was smooth, nanostructured, nonporous, and yellow. Pristine surfaces with high density of hydroxyl-groups were protected during storage using a removable cell-friendly layer that allowed dry packaging. CONCLUSIONS A novel anodized implant system was developed with surface chemistry, topography, nanostructure, color, and surface energy designed to balance the clinical and biological needs at every tissue level.

Background Telescopic prostheses are an evidence-based treatment modality, and conical zirconia crowns and electro-formed gold copings have been used for dentures supported by teeth and/or implants. Purpose We aimed to evaluate the survival rates of zirconia-based tooth/implant restorations. Materials and methods A total of 126 telescopic overdentures, all retained by conical zirconia crowns and electro-formed gold copings, were retrospectively evaluated and failures analyzed for abutment configurations. Survival rates and modifying factors were evaluated by Kaplan-Meier analysis, log-rank testing, and Cox regression analysis. Results We evaluated observation periods of up to 11.5 years (mean: 45.25 ± 25.11 months). Five-year prosthesis survival was 96.9 ± 2.2% (95% CI: 92.6-100). Six dentures had been lost, and these failures were significantly associated with specific abutment configurations. Conclusions Within the limitations of this retrospective study, the concept of conical zirconia telescoping into electro-formed gold provides a viable alternative to other telescopic designs used for removable dental prostheses. The concept is well suited especially for tooth/implant-supported prosthetic rehabilitation.

OBJECTIVE: The purpose of this study was to evaluate the sterilization effectiveness against biofilms on retrieved healing abutments used in implant dentistry. BACKGROUND: A large number of clinicians reuse healing abutments to decrease treatment costs although it can promote infection due to the presence of remnant biofilm biomass. METHODS: One hundred and eighty-five titanium healing abutments previously used for 3 months in oral cavity were assessed in this study. Abutments were submitted to cleaning, chemical disinfection, and autoclave sterilization according to clinical guidelines. The abutments were aseptically placed into glass tubes containing specific bacterial growth medium and then incubated for 10 days. From glass tubes with bacterial growth, 100 µl medium was transferred to Schaedler's agar for morphological identification and counting of strict anaerobes and to Columbia blood agar for presumptive identification of facultative anaerobes after incubation. Isolated strains were then identified at species level by enzymatic and biochemical tests within API microorganism detection platform. Also, polymerase chain reaction (PCR) was performed for identification of undefined strains. RESULTS: After the standard cleaning and sterilization procedures, fifty-six (approximately 30%) retrieved abutments showed the presence of remnant biofilm biomass. The bacteria identified into the remnant biofilms covering the abutments were representative of the commensal oral microbiota including Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Enterococcus faecalis. CONCLUSION: Although some healing abutments did not reveal the existence of bacteria, organic components from biofilm biomass are still strongly adhered on the retentive micro-regions and surfaces of abutments and therefore that would support the accumulation of biofilm including pathogenic species leading to patients' cross-infections. Further studies should be performed on the assessment of different materials, design, and connections of the healing abutments associated with clinical disinfection procedures in implant dentistry. ispartof: JOURNAL OF PERIODONTAL RESEARCH vol:56 issue:2 pages:415-422 ispartof: location:United States status: published

Objective The purpose of this laboratory study was to evaluate the fatigue resistance, fracture resistance and mode of failure of posterior hybrid-abutment-crown vs. hybrid-abutment with separate crown, both bonded to short titanium bases. Materials and methods Thirty-two titanium implants were embedded perpendicularly in auto-polymerizing resin. Implant-supported restorations simulating a maxillary first premolar were designed and milled using a CAD/CAM system and divided into 2 groups according to material (n = 16): zirconia (Z) and lithium disilicate (L). Each group was subdivided into two subgroups according to design (n = 8): hybrid-abutment-crown (ZS, LS) and hybrid-abutment with separate crown (ZC, LC). Each group was subjected to 1.2 million cycles of thermo-mechanical fatigue loading in a dual-axis chewing simulator at 120 N load. Surviving specimens were subjected to quasi-static loading in a universal testing machine. Mode of failure was determined under a low magnification optical microscope. Results During chewing simulation, 18.8% of zirconia and 43.8% of lithium disilicate restorations failed. The fracture resistance median values ranged from 3,730 N for group ZC, 3,400 N for group ZS, 1,295 N for group LS to 849 N for group LC. Group ZC had a statistically significant higher fracture resistance than groups LC and LS; however, it did not differ significantly from group ZS (p ≤ 0.05). Failures were seen in both titanium bases and ceramic superstructure. Conclusions Zirconia and lithium disilicate hybrid implant-supported restorations with short (3 mm) titanium bases failed in a considerable number already during chewing simulation. Therefore, despite their high fracture strength the use in the posterior region should be considered critically.

BACKGROUND It is unknown whether it is possible to measure implant stability with polyetheretherketone (PEEK) healing abutments using electronic percussive testing (EPT). PURPOSE To investigate the reliability of the percussive test values (PTVs) measured with PEEK healing abutments and to compare them with the PTVs measured with titanium healing abutments. MATERIAL AND METHODS Thirty dental implants were inserted into the fresh pelvis belonging to a cow. Titanium healing abutments (2 and 5 mm), PEEK healing abutments (5 mm), and prepable standard titanium abutments (5 mm) were screwed to the implants, respectively, and PTVs were measured by two examiners using a wireless EPT device. Differences in PTVs between different dental implant components were evaluated using Friedman's test with post hoc Wilcoxon signed-rank test and Bonferroni correction. Inter and intra-observer reliabilities were detected using interclass correlation coefficients (ICCs) RESULTS: The mean PTVs obtained using the PEEK healing abutments were significantly higher than the mean PTVs obtained using the other abutments for both examiners (P

The present study used a new, digitized version of the impression replica technique, namely the dual-scan technique, to evaluate the adaptation of single-crown fixed dental prostheses (FDPs). Scans of the bare master model and of the master model with a silicone layer representing the cement layer were superimposed and analyzed using designated software. Single crowns produced using the lost-wax metal casting technique were included. The cement space of the band width, 0.5-1.0 mm from the preparation margin (marginal fit), was smallest for crowns made from laser-sintered cobalt-chromium. The internal fit in both mesial-distal and buccal-palatal directions was statistically significantly better for crowns made using the conventional lost-wax metal casting technique than for crowns produced using computer-aided design/computer-aided manufacturing (CAD/CAM). Fixed dental prostheses produced by milled cobalt-chromium had the loosest internal fit. The results agree with those of our previous study of the same test specimens, in which the triple-scan method was used, and imply that the dual-scan method is well suited for adaptation studies.

OBJECTIVES The objective of this systematic review was to assess the influence of implant-abutment connection and abutment material on the outcome of implant-supported single crowns (SCs) and fixed dental prostheses (FDPs). METHODS An electronic Medline search complemented by manual searching was conducted to identify randomized controlled clinical trials, prospective and retrospective studies with a mean follow-up time of at least 3 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using robust Poisson regression, and comparisons were made with multivariable Poisson regression models. RESULTS The search provided 1511 titles and 177 abstracts. Full-text analysis was performed for 147 articles resulting in 60 studies meeting the inclusion criteria. Meta-analysis of these studies indicated an estimated 5-year survival rate of 97.6% for SCs and 97.0% for FDPs supported by implants with internal implant-abutment connection and 95.7% for SCs and 95.8% for FDPs supported by implants with external connection. The 5-year abutment failure rate ranged from 0.7% to 2.8% for different connections with no differences between the types of connections. The total number of complications was similar between the two connections, yet, at external connections, abutment or occlusal screw loosening was more predominant. Ceramic abutments, both internally and externally connected, demonstrated a significantly higher incidence of abutment fractures compared with metal abutments. CONCLUSION For implant-supported SCs, both metal and ceramic abutments with internal and external connections exhibited high survival rates. Moreover, implant-supported FDPs with metal abutments with internal and external connections for also showed high survival rates.

OBJECTIVES To investigate the impact of progressive bone loss in an experimental peri-implantitis model in the dog upon the implant stability quotient (ISQ) measured in the course of induced and spontaneous conditions of disease, and to evaluate the association between the clinical parameters and ISQ. MATERIALS AND METHODS Seventy-two implants were placed in 12 Beagle dogs. Of these, 36 implants in six dogs were assessed during ligature-induced peri-implantitis (three timepoints) and at one timepoint following a period of spontaneous progression. The ISQ was recorded using resonance frequency analysis (RFA). Furthermore, the clinical peri-implant parameters were registered at four sites per implant at each timepoint. Marginal bone loss (MBL) was determined using computed tomography at four sites per implant and bone-to-implant contact (BIC) was assessed from histological samples. A linear regression model was estimated by generalized estimation equations (GEEs) in order to study the MBL-ISQ values at each measurement timepoint. Pearson's correlation test was applied. RESULTS None of the implants failed during the study period. At implant level, a strong negative correlation was found for all timepoints between ISQ and MBL (r = -0.58; p

OBJECTIVES To assess the early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single-tooth implant-supported reconstructions. MATERIALS AND METHODS Patients with single-tooth implants were randomly allocated to receive a cemented lithium disilicate crown on a customized zirconia abutment (CEM) or a screw-retained crown with a directly veneered zirconia abutment (SCREW). At the screening visit, at crown insertion and at the 6-month follow-up, clinical parameters were measured at the implant and the contralateral tooth. Marginal bone levels, technical parameters, and esthetic outcomes were measured at the implants. At the 6-month follow-up, a microbiological test was performed and a soft tissue biopsy was harvested at the implants for histological analysis. Inflammatory cells and fibroblasts/-cytes were analyzed at the level of the sulcular epithelium, junctional epithelium, and connective tissue. The histological parameters were analyzed by means of a linear mixed model. RESULTS Thirty-three patients completed the study, and implant and crown survival rates were 100% at 6 months. Histologically, the number of inflammatory cells tended to be higher in group CEM (p > 0.05). Moreover, significantly less inflammatory cells and fibroblasts/-cytes were found in the sulcular epithelium compared to the junctional epithelium and supracrestal connective tissue (p < 0.001). Four patients were tested positive for periodontal marker pathogens at the 6-month follow-up, and three of them belonged to group CEM. From crown insertion to the 6-month follow-up, median marginal bone levels changed only minimally and measured 0.31 and 0.32 mm in group CEM and 0.47 and 0.36 mm in group SCREW, respectively. Clinical and esthetic parameters remained stable over time and were comparable between natural teeth and implants as well as between the groups. CONCLUSIONS Cemented reconstructions were associated with more inflammatory cells, and more patients were diagnosed with periodonto-pathogens. Both types of reconstructions resulted in similar radiological (marginal bone levels) and clinical outcomes (bleeding on probing and probing depth).