Implant-supported Single Crowns Research Articles

Aesthetic outcomes of different materials for delayed, single-tooth restorations for immediately placed implants. A randomized controlled clinical trial

ObjectivesThe aim of this study is to compare the aesthetic outcomes of metal porcelain (C), lithium disilicate (T1) and porcelain-layered zirconium (T2) immediate implant-supported single crowns in the anterior maxilla. Materials and methodsForty-five immediate dental implants were provided for 45 patients that required the extraction of a single tooth in the anterior maxilla. A temporary prosthesis was provided at 8 weeks after placement followed by the final prosthesis at 24 weeks post-implantation. The patients were randomly allocated into 3 groups: 15 patients in the control group (C) received a metal-porcelain restoration, 15 patients (T1) received a lithium disilicate (LD) restoration and 15 patients (T2) received a porcelain-layered, zirconium (Z) restoration. Pink (PES) and White (WES) esthetic scores, radiographic bone levels, periodontal parameters and patient's esthetic satisfaction using a visual analogue scale (VAS) were evaluated at the time of final restoration placement (t0) and at 12-months post-loading (t12). ResultsNo implants were lost during the duration of this study. Statistically significant higher WES and VAS scores (p < 0.05) were recorded in T1 vs C and T1 vs T2 groups respectively. Similar radiographic bone levels and periodontal parameters were recorded in all groups. ConclusionWithin the limitations of this study, it was concluded that T1 restorations provided better WES outcomes when compared to C restorations and better VAS scores when compared to T2 restorations at 12 months post-loading. Besides, different material interphases did not have an impact in PES, bone levels or periodontal parameters. Clinical relevanceThere is limited data comparing aesthetic outcomes of implant supported single crowns made of different ceramic materials based on accepted and comparable indexes and the evaluation of the patient's perspective regarding these aesthetic outcomes.

Static and dynamic stress analysis of different crown materials on a titanium base abutment in an implant-supported single crown: a 3D finite element analysis

BackgroundThis Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components.MethodsFive distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment. For the static load, a 100 N oblique load was applied to the buccal incline of the palatal cusp of the maxillary right first premolar. The dynamic load was applied in the same way as in static loading with a frequency of 1 Hz. The principal stresses in the peripheral bone as well as the von Mises stresses and fatigue strength of the implants, abutments, prosthetic screws, and crowns were assessed.ResultsAll of the models had comparable von Mises stress values from the implants and abutments, as well as comparable maximum and minimum principal stress values from the cortical and trabecular bones. The PEEK crown showed the lowest stress (46.89 MPa) in the cervical region. The prosthetic screws and implants exhibited the highest von Mises stress among the models. The lithium disilicate crown model had approximately 9.5 times more cycles to fatique values for implants and 1.7 times more cycles to fatique values for abutments than for the lowest ones.ConclusionsWith the promise of at least ten years of clinical success and favorable stress distributions in implants and prosthetic components, clinicians can suggest using an implant-supported lithium disilicate crown with a titanium base abutment.

Monolithic Zirconia Single Crowns Supported by Narrow or Standard Diameter Titanium-zirconium Implants in Posterior Sites: One-year Results of a Randomized Controlled Trial.

The replacement of missing teeth with implant-supported prostheses has become a standard treatment option with reliable long-term outcomes in various clinical indications.1-6 The implant-supported single crowns, in particular, presented the most favorable outcome with a survival rate of 89.5% to 96% over a 10-year period.5,6 A notable prosthetic maintenance requirement, however, was reported irrespective of the prosthetic material used for the crown construction.1,7 Metal-ceramic restorations have been considered the gold standard when replacing single or multiple missing teeth with implant-supported fixed dental prostheses.8 A systematic review of 4363 metal-ceramic implant-supported single crowns in the anterior and posterior region reported an impressive survival rate of 98.3% over five years.9 Yet, the biologic and prosthetic complications associated with these restorations were substantial with a rate of 13.5%. In the posterior region, a recent systematic review of short-term randomized controlled trials10 reported a survival rate of 99.1% for metal-ceramic implant-supported single crowns. The reported prosthetic complications, mainly ceramic chipping, were also notable with an incidence rate of 7.6%.mIn recent years, the introduction of high-strength all-ceramic materials as well as digitaldesign and manufacturing processes, has allowed faster fabrication of more esthetic and cost effective restorations.11 Zirconia-based fixed dental prostheses on teeth and implants are now increasingly used and show 5-year cumulative survival rates of 89.4 to 100%.12 These restorations are typically made up of a zirconia framework that is veneered with a layer of glass ceramic to impart translucency for enhanced esthetics.13 However, chipping of the ceramic layer has been a lingering issue, shifting the attention toward the use of full anatomic monolithic zirconia restorations.14,15 Replacement of missing teeth with dental implants in posterior ridges with limited bone width can be surgically challenging and the notion of narrow diameter implants has been suggested.16,17 These implants were thought to offer potential advantages in terms of costeffectiveness and surgical morbidity.18,19 The literature, however, remains controversial on treatment outcomes with narrow diameter implants, particularly in posterior sites.19-21 When single tooth replacement with monolithic zirconia implant-supported single crowns in posterior sites are considered, only short to medium-term outcomes are available.22-26 The survival rates and clinical performances reported in these studies were variable. Crown survival rates between 84% and 100% were demonstrated over an observation time of one to three years, while the prosthetic complications were between 0% to 14%. In three studies,22,23,25 standard diameter titanium implants were used in premolar and molar sites to support the single crowns. The remaining two studies by Mühlemann et al. (2020) and Zumstein et al. (2023) reported the one-year and three-year outcomes, respectively, of the same cohort. In these studies, narrow titanium-zirconium (TiZr) implants of 3.3 mm diameter were exclusively utilized in molar sites. The implant and crown survival rates reported at one and three years were 97.4% and 84%, respectively. The lower survival rate observed in the report of Zumstein et al. (2023) resulted from fracture of five implants and the subsequent loss of their respective crowns. Aside from these two reports, no other information on the outcomes of monolithic zirconia single crowns supported by narrow diameter TiZr implants in posterior sites are available. The validity of this treatment, therefore, needs further investigation with well-designed clinical trials. Hence, a randomized controlled trial was undertaken to assess various implant, prosthetic, and patient-reported outcomes of monolithic zirconia single crowns supported by either narrow or standard diameter titanium-zirconium (TiZr) implants in posterior sites. The present report focuses on the one-year prosthetic results.

Influence of ceramic crown design (translucent monolithic zirconia vs. bilayered) of implant-supported single crowns after mechanical cycling.

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. 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. 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). Translucent monolithic zirconia crowns exhibited significantly higher fatigue and fracture resistance compared with conventional MC and bilayered crowns. 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.

Single missing molar with wide mesiodistal length restored using a single or double implant-supported crown: A self-controlled case report and 3D finite element analysis.

Based on a self-controlled case, this study evaluated the finite element analysis (FEA) results of a single missing molar with wide mesiodistal length (MDL) restored by a single or double implant-supported crown. A case of a missing bilateral mandibular first molar with wide MDL was restored using a single or double implant-supported crown. The implant survival and peri-implant bone were compared. FEA was conducted in coordination with the case using eight models with different MDLs (12, 13, 14, and 15 mm). Von Mises stress was calculated in the FEA to evaluate the biomechanical responses of the implants under increasing vertical and lateral loading, including the stress values of the implant, abutment, screw, crown, and cortical bone. The restorations on the left and right sides supported by double implants have been used for 6 and 12 years, respectively, and so far have shown excellent osseointegration radiographically.The von Mises stress calculated in the FEA showed that when the MDL was >14 mm, both the bone and prosthetic components bore more stress in the single implant-supported strategy. The strength was 188.62-201.37 MPa and 201.85-215.9 MPa when the MDL was 14 mm and 15 mm, respectively, which significantly exceeded the allowable yield stress (180 MPa). Compared with the single implant-supported crown, the double implant-supported crown reduced peri-implant bone stress and produced a more appropriate stress transfer model at the implant-bone interface when the MDL of the single missing molar was ≥14 mm.

Effectiveness of the full digital flow in the confection of implant-supported single prostheses and comparative analysis between two techniques: with an abutment or direct. Cross-sectional cohort.

With technological advances in Dentistry, the search for more predictable, integrated, and agile planning and treatments increases. In Implantology, despite the digital flow being greatly encouraged, doubts remain about its technical success. Therefore, the aim of this clinical study was to evaluate the effectiveness of the full digital flow using two techniques for the fabrication of implant prostheses: with an abutment or direct to the implant, comparatively evaluating the time required for interproximal adjustment to adapt the crowns, occlusal adjustment, and the need to return to the laboratory for corrections. The sample consisted of 46 patients who underwent the installation of 75 implants, treated at the ILAPEO School of Dentistry surgical clinic. They were all over 18, of both sexes and received implants in single edentulous spaces that required rehabilitation with crowns. These patients were divided into two groups, with Group I (G1), comprising 27 patients (38 implants) who had received abutments at the time of surgery, and Group II (G2) comprising 28 patients (37 implants) who had received healing caps, with 9 patients in common in both groups. In G1, scan bodies adapted to the abutments were used. In G2, they were directly adapted to the implants. The cases were scanned and sent to the laboratory. When the crowns were installed, the prosthesis adjustment data was recorded (in seconds), as well as the need to return to the laboratory for adjustments and corrections. The data from the groups were compared using the Mann-Whitney non-parametric test. There were no statistical differences in terms of occlusal and proximal adjustment time. The need to return prosthetic work to the laboratory was compared between the groups using the chi-squared test. The GraphPad Prism 8 software (San Diego, CA, USA) was used for the statistical analysis, and all tests were applied at a significance level of 5%. Data analysis leads to the conclusion that digital flow made it possible to obtain satisfactory implant-supported single crowns in both groups. No differences were found between the two techniques regarding the time taken to adapt to the mouth and the need to return to the laboratory.

A fully digital workflow to design anterior guidance for an implant-supported single crown using a modified patient-specific motion technique

Current methods for designing anterior guidance of anterior fixed prostheses are either complicated or lack accuracy. The article describes a fully digital workflow to design individualized anterior guidance of an implant-supported single crown by using a modified patient-specific motion technique. The technique aims to optimize the digital occlusal design workflow, thereby improving the occlusal fit and long-term stability of anterior fixed prostheses.

Clinical outcomes of tooth- and implant-supported restorations performed in a university-based undergraduate program after 13-15 years.

To assess the clinical concept of patient treatment with fixed tooth- and implant-supported restorations in a university-based undergraduate program after 13 - 15 years. Thirty patients (mean age 56 years) who had received multiple tooth- and implant-supported restorations were recalled after 13-15 years. The clinical assessment comprised of biological and technical parameters as well as patient satisfaction. Data were analyzed descriptively and the 13-15-year survival rates for tooth- and implant-supported single crowns and fixed dental prostheses were calculated. The survival rate of tooth-supported restorations amounted to 88.3% (single crowns) and 69.6% (fixed dental prostheses); in implants it reached 100% for all types of reconstructions. Overall, 92.4% of all reconstructions were free of technical complications. The most common technical complication was chipping of the veneering ceramic (tooth-supported restorations: 5.5%; implant-supported restorations: 13-15.9%) regardless of the material used. At teeth, increased probing depth ≥5mm was the most frequent biological 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. 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 biological complications occurrs in reconstructed teeth, whereas implant-supported restorations are more prone to technical complications.

Aesthetic Outcome and Patient Perception of Immediate vs. Delayed Loading of Implant-Supported Single Crowns: A Randomized Controlled Trial

ABSTRACT Background: This randomized controlled trial aimed to compare the aesthetic outcome and patient perception of immediate versus DL of implant-supported single crowns. Methods: A total of 60 patients with a single missing tooth were enrolled and randomly assigned to two groups: immediate loading (IL) and delayed loading (DL). Each group consisted of 30 patients with a total of 30 implants. In the IL group, crowns were loaded onto implants immediately after placement, while in the DL group, a healing period of 3 months was observed before crown placement. Aesthetic outcome was assessed using the Pink Esthetic Score (PES) for soft tissue and the White Esthetic Score (WES) for the crown. Patient perception was evaluated through a visual analog scale (VAS) for satisfaction, comfort, and overall experience. Results: The IL group demonstrated comparable aesthetic outcomes to the DL group, with mean PES and WES scores of 10.2 ± 1.5 and 8.7 ± 1.2, respectively, in the IL group, and 10.5 ± 1.3 and 8.5 ± 1.4 in the DL group. Patient perception in terms of satisfaction, comfort, and overall experience was similarly high in both groups, with VAS scores above 8 for each parameter. Conclusion: This randomized controlled trial suggests that both IL and DL of implant-supported single crowns result in favorable aesthetic outcomes and high levels of patient satisfaction.

A two-year prospective study to compare the peri-implant parameters of posterior implant-supported single crowns with and without mesial proximal contact loss

Background/purposeInterproximal contact loss may lead to food impaction and result in subsequently periodontal complications. The purpose of this prospective study was to investigate the peri-implant parameters of posterior implant-supported single crowns (SCs) with and without mesial proximal contact loss after 2 years of follow-up. Material and methodsTwenty-six patients with a total of 40 posterior implant-supported SCs with mesial adjacent natural teeth were observed for 24 months after crown insertion. The mesial proximal contacts were assessed by dental floss, then were classified as tight, weak, and open contacts. The following peri-implant parameters were evaluated, including modified plaque index (MPI), modified gingival index (MGI), and probing depth (PD) were conducted at six sites per tooth (mesiofacail, midfacial, distofacial, mesiolingual, mid-lingual and distolingual) in the 6-, 12-, 18- and 24-month following visits. Furthermore, radiographs were taken regularly in 12- and 24-month recall sections for measuring the marginal bone loss (MBL). ResultsAt 12-month observation, the incidence rates of weak and open contacts were 22.5 % and 12.5 %; whereas after 24 months of clinical service, the rates came up with 12.9 % and 25.6 %, respectively. No significant differences were found between the tight, weak, and open contact groups in the parameters of MPI, MGI, or PD (P > 0.05) at 12- and 24-month follow-up. None of the mean differences of the peri-implant parameters: MPI, MGI, PD and MBL had significant differences between the tight, weak, and open contact groups after 1 and 2 years of clinical service (P > 0.05). ConclusionThe presence of open, weak, and tight mesial proximal contacts had no significant effects on the peri-implant tissue conditions.

Effect of customized abutment taper configuration on bone remodeling and peri-implant tissue around implant-supported single crown: A 3D nonlinear finite element study.

The optimal configuration of a customized implant abutment plays a crucial role in promoting bone remodeling and maintaining the peri-implant gingival contour. However, the biomechanical effects of abutment configuration on bone remodeling and peri-implant tissue remain unclear. This study aimed to evaluate the influence of abutment taper configurations on bone remodeling and peri-implant tissue. Five models with different abutment taper configurations (10°, 20°, 30°, 40°, and 50°) were analyzed using finite element analysis (FEA) to evaluate the biomechanical responses in peri-implant bone and the hydrostatic pressure in peri-implant tissue. The results demonstrated that the rate of increase in bone density was similar in all models. On the other hand, the hydrostatic pressure in peri-implant gingiva revealed significantly different results. Model 10° showed the highest maximum and volume-averaged hydrostatic pressures (69.31 mmHg and 4.5 mmHg), whereas Model 30° demonstrated the lowest values (57.83 mmHg and 3.88 mmHg) with the lowest excessive pressure area. The area of excessive hydrostatic pressure decreased in all models as the degree of abutment taper increased from 10° to 30°. In contrast, Models 40° and 50° exhibited greater hydrostatic pressure concentration at the cervical region. In conclusion, the abutment taper configuration had a slight effect on bone remodeling but exerted a significant effect on the peri-implant gingiva above the implant platform via hydrostatic pressure. Significant decreases in greatest and average hydrostatic pressures were observed in the peri-implant tissues of Model 30°. However, the results indicate that implant abutment tapering wider than 40° could result in a larger area of excessive hydrostatic pressure in peri-implant tissue, which could induce gingival recession. This article is protected by copyright. All rights reserved.

Clinical and Radiographic Evaluation of Short Locking-Taper Implants Supporting Single Crowns in the Posterior Region: A 12-Year Retrospective Study.

Few studies have reported the outcomes of short implants with a follow-up time longer than 10 years. This retrospective study aimed to evaluate the long-term outcomes of the short locking-taper implants supporting single crowns in the posterior region. Patients who received short locking-taper implants (≤ 8 mm) supporting single crowns in the posterior region from 2008 to 2010 were included. The clinical outcomes, radiographic outcomes, and patient satisfaction were recorded. As a result, a total of 18 patients with 34 implants were included. The cumulative survival rate was 91.4% and 83.3% at implant level and patient level, respectively. Tooth brush habit and history of periodontitis were significantly associated with implant failure (P < .05). The median marginal bone loss (MBL) was 0.24 mm (interquartile range: 0.01 to 0.98). Biologic and technical complications occurred in 14.7% and 17.8% implants, respectively. The mean modified sulcus bleeding index and mean peri-implant probing depths were 0.52 ± 0.63 and 2.38 ± 0.79 mm, respectively. All patients were at least quite satisfied, with the majority of patients being fully satisfied (88.9%) with the treatment. Within the limitations of this study, the short locking-taper implants supporting single crowns in the posterior region achieved promising outcomes in the long-term follow-up.

Digitally designed occlusion of an implant-supported crown considering physiological tooth displacement under occlusal loading

Physiological natural tooth displacement under occlusal loading can influence intraoral occlusal contacts. However, gypsum casts and digital scans cannot simulate the physiological tooth displacement under occlusal loading. The occlusal design of the implant-supported crowns has been based mainly on the experience of dental laboratory technicians, lacking accuracy and individualization. Therefore, a digital technique that considers physiological tooth displacement is presented to design the occlusion of implant-supported single crowns.

The Influence of Crown-to-Implant Ratio on Crestal Bone Loss at Implants with Single Crowns and Bridges.

To evaluate how the crown-to-implant (C/I) ratio affects the loss of crestal bone at single-crown implants and bridges in patients with periodontal disease. Thirty-nine patients treated for periodontitis were rehabilitated with 108 implant-supported single crowns and bridges. Each patient was examined over a 5- to 20-year period on a 3 to 6-month recall schedule. At each session, we recorded periodontal clinical parameters. In addition, intraoral radiographs were taken after superstructure insertion (baseline) and then at 1, 3, 5, 10, 15, and 20 years. The study population was divided by anatomical C/I ratio (C/I ≤1, group 1 or C/I 1, group 2). Implants had a 96.2% 5-year survival rate, and 92.6% 20-year survival rate. The overall prevalence was 10.1% for mucositis and 1.1% for peri-implantitis. The survival rate (p = 0.68), mucositis (p = 0.325), or peri-implantitis (p = 0.077) did not significantly differ in the group comparison. The mean annual peri-implant bone loss was 0.09 0.41 mm and not significantly different between the groups. Mean bone loss was not significantly different until the 10th year of observation, during which group 2 presented significantly less bone loss. The correlation of annual bone loss and clinical C/I ratio showed a small but significant negative effect throughout the entire study period (R = -0.217; p <0.01). Increased crestal bone loss was not observed with implants with higher C/I ratios, both anatomical and clinical, and they even showed signs of less crestal bone loss.

Implant-Supported Single Crowns With Hybrid Abutments Show Favorable Short-Term Clinical Outcomes

Clinical performance of implant-supported single hybrid abutment crown restoration: A systematic review and meta-analysis. Journal of Prosthodontic Research. Zhang, M., Ho, D. K. L., Pelekos, G., & Fok, M. R. JPR_D_22_00279. SOURCE OF FUNDING: No funding was received. Systematic review and meta-analysis.

Virtual implant scan body switch by using computer-aided design programs avoiding the need of obtaining a new intraoral implant digital scan: A novel protocol.

The present manuscript describes a technique to virtually switch an implant scan body eliminating the need of obtaining a new intraoral implant digital scan. Implant scan bodies assist on transferring the 3-dimensional position of the implants into the virtual definitive implant cast. However, if a different implant part is desired during the designing procedures of the implant restoration such as selecting a different implant abutment of varying height, angulation, or manufacturer, a new intraoral implant digital scan with the specific implant scan body is required. This novel protocol aims to reduce possible complications that require capturing a new intraoral implant digital scan, facilitate prostheses design modifications after the obtention of the definitive intraoral implant digital scan, and to ease the manufacturing procedures. The novel technique may provide a solution for virtually switch implant scan bodies for fabricating implant-supported single crowns or short-span prostheses. Additional studies are needed before its clinical implementation.

Risk Factors Associated with Failure and Technical Complications of Implant-Supported Single Crowns: A Retrospective Study.

Background and Objectives: Implant-supported single crowns have become a routine approach for the replacement of missing single teeth, being considered as one of the most common ways of rehabilitation when adjacent teeth are healthy. The present retrospective study aimed to investigate the risk factors possibly associated with failure and technical complications of implant-supported single crowns and their supporting implants. Materials and Methods: Patients treated at one faculty (2009-2019) were considered for inclusion. Complications investigated included ceramic fracture/chipping, crown loss of retention/mobility, crown failure/fracture, loosening/loss/fracture of prosthetic screw, and implant failure/fracture. Any condition/situation that led to the removal/replacement of crowns (implant failure not included) was considered prosthesis failure. Univariate/multivariate Cox regression models were used to evaluate the associations between clinical covariates and failure. Results: 278 patients (358 crowns) were included. Mean ± SD follow-up was 56.5 ± 29.7 months. Seven implants (after a mean of 76.5 ± 43.7 months) and twenty crowns (21.3 ± 23.5 months) failed. The cumulative survival rate (CSR) for crowns was 93.5% after 5, remaining at 92.2% between 6 and 11 years. The most common reasons for crown failure were porcelain large fracture (n = 6), crown repeatedly loose (n = 6), and porcelain chipping (n = 5). Men and probable bruxism were identified in the Cox regression model as being associated with crown failure. The most common observed technical complications were mobility of the crown and chipping of the ceramic material, with the latter being observed even in crowns manufactured of monolithic zirconia. Cases with at least one technical complication (not considering loss of screw hole sealing) were more common among probable bruxers than in non-bruxers (p = 0.002). Cases of ceramic chipping were more common among bruxers than in non-bruxers (p = 0.014, log-rank test). Conclusions: Probable bruxism and patient's sex (men) were factors associated with a higher risk of failure of implant-supported single crowns.

Cumulative success rate and marginal bone loss for immediate and early loading protocols in a single implant-supported crown: A randomized controlled split-mouth clinical trial

Statement of problemNew loading protocols with reduced treatment time have gained popularity because of their advantages. However, whether the success rate with immediate loading (IL) is worse than with early loading (EL) is still unclear. PurposeThe purpose of this randomized controlled trial with a split-mouth design was to evaluate the marginal bone loss and the cumulative success rate (CSR) 1 year after an IL protocol in single implant-supported crowns. The test groups were loaded after less than 24 hours (test group) and EL at 60 days (control group). Material and methodsSeventeen participants received 34 implants. The recall appointments were at baseline, 30 days, 60 days, and 1 year. The outcome measures evaluated were pain, implant clinical mobility, probing depth measurements, peri-implant disease, marginal bone loss, implant insertion torque, implant stability quotient (ISQ) value, and the CSR. A 2-way repeated measures ANOVA identified the significant differences for probing depth and ISQ. A 3-way repeated measures ANOVA followed by a pairwise t test analyzed marginal bone loss, and a nonparametric Wilcoxon test analyzed insertion torque (α=.05). ResultsNo differences were found between the insertion torque, ISQ, and marginal bone loss values (P>.05). When analyzing probing depth, no differences were found when comparing IL versus EL at baseline, 30 days, and 1 year (P>.05). The global CSR was 91.17%, 88.23% for the IL group and 94.11% for the EL group. ConclusionsWhen analyzing marginal bone loss, the groups were similar. The global CSR was 91.17%, 88.23% for the IL group, and 94.11% for the EL group.

Effect of gingival height of a titanium base on the biomechanical behavior of 2-piece custom implant abutments: A 3-dimensional nonlinear finite element study

Statement of problemTitanium base (TiBase) abutments to restore an implant-supported single crown are available in different gingival heights, but information on the biomechanical effects of the gingival heights is lacking. PurposeThe purpose of this nonlinear finite element analysis study was to evaluate the effects of TiBase gingival heights on the biomechanical behavior of custom zirconia (CustomZir) abutments and TiBase, including von Mises stress and maximum and minimum principal stress. Material and methodsTiBases with different gingival heights (0.5 mm, 1 mm, 1.5 mm, and 2 mm) with internal hexagon Morse taper connections were simulated in 3-dimensional models. The simulations (ANSYS Workbench 2020; ANSYS Inc) included the OsseoSpeed EV implant (Ø5.4 mm) (AstraTech; Dentsply Sirona), restoration, and surrounding bone in the mandibular first molar region. An occlusal force of 200 N was applied with a 2-mm horizontal offset toward the buccal side and a 30-degree inclination from the vertical axis. ResultsHigh-stress concentration was observed in the uppermost internal connection area on the buccal side and the antirotational part of the titanium abutment on the lingual side in all models. CustomZir abutments with a shorter gingival height exhibited larger concentrated areas of volume average stress von Mises stress and higher magnitude of maximum and minimum principal stress compared with a taller gingival height. ConclusionsA TiBase abutment with a taller gingival height reduced the fracture risk of a CustomZir abutment without increasing any mechanical risk.

Failure resistance of single-implant crowns assembled from polyetheretherketone and lithium disilicate abutments and different crown materials after artificial aging.

To investigate the effect of using different materials for the fabrication of implant abutments and crowns on the mechanical behavior of implant-supported single crowns after artificial aging. The materials were tested in different combinations to reveal whether using stiff or resilient materials as an abutment or a crown material might influence the fracture strength of the whole structure. A total of 40 implants (blueSKY, bredent GmbH & Co. KG) were restored with identical custom-made CAD/CAM abutments milled out of lithium disilicate or ceramic-reinforced PEEK and were divided into 5 test groups (n = 8 each). Forty crowns made of three different materials (zirconia, lithium disilicate, and ceramic-reinforced PEEK) were used to restore the abutments. Specimens were subjected to mechanical load up to 1,200,000 cycles in a chewing simulator (Kausimulator, Willytech) with additional thermal cycling. The surviving specimens were subjected to quasi-static loading using a universal testing machine (Z010, Zwick). PEEK abutments with zirconia crowns showed the highest median failure load (3890.5 N), while PEEK abutments with lithium disilicate crowns exhibited the lowest (1920 N). Fracture and deformation occurred in both crowns and abutments. The failure load of the restorations was influenced by the material of the abutment and the crown. Restoring PEEK abutments with zirconia crowns showed a high failure load and no screw loosening.