Base Abutments Research Articles

Clinical outcomes of single implant supported crowns utilising the titanium base abutment: A 7.5-year prospective cohort study

ObjectiveTo assess radiographic, clinical and patient-reported outcomes of single zirconia implant-supported crowns on titanium base abutments (TBA) over a 7.5-year period. MethodsTwenty-four patients received bone-level titanium implants and screw-retained zirconia implant crowns utilising TBA. Marginal bone level (MBL), clinical parameters (probing depth-PD, bleeding on probing-BoP, plaque control record-PCR), technical complications (USPHS criteria) and patient satisfaction were assessed at crown delivery (baseline), 1 year (FU-1) and at 7.5 years (FU-7.5) of follow-up. ResultsEighteen patients were available for re-examination at 7.5 years. The mean MBL at FU-7.5 (0.35 ± 0.20mm) did not significantly change compared to baseline (0.54 ± 0.39, p=.352) and to FU-1 (0.54 ± 0.45mm, p=0.524). From baseline to 7.5 years, the mean PD increased significantly, from 3.0 ± 0.6mm to 3.7 ± 0.8mm (p=0.005). However, BoP and PCR did not significantly change; (BOP: from 27.1 ± 20.7% to 25.0 ± 20.0%, p=0.498; PCR: from 11.1 ± 21.2% to 25.0 ± 25.1%, p=0.100). Nine patients presented with more than one bleeding site. This denoted a peri-implant mucositis prevalence of 50%, whilst none of the implants presented peri-implantitis. One incidence of minor and major ceramic chipping were reported on 2 out of the 18 crowns, resulting in a prosthetic survival rate of 94.4%. Seventeen patients were highly satisfied with their result. ConclusionSingle implant-supported zirconia crowns on TBA displayed: (i) minor number of technical complications, (ii) high prosthetic survival rate, (iii) stable marginal bone level and (iv) high patient satisfaction at 7.5 years. Clinical implicationsTitanium base abutments despite their high use in clinical practice, lacked medium- and long-term studies. The presented findings highlight their clinical performance at 7.5 years as they display satisfying radiographic, clinical and patient-related outcomes. TBA appear to be a suitable abutment choice for medium-term implant-supported restorations.

Effect of Titanium Base Abutment Height and Restorative Material on Torque Maintenance of Hybrid-abutment Restoration with Offset Implant Placement.

The purpose of this in vitro study was to evaluate the effect of titanium base height on torque loss of monolithic zirconia, lithium disilicate, and polymer-infiltrated ceramic hybrid- abutment restorations for offset placed implant. Forty-two hybrid- abutment restorations supported by offset placed implants (diameter: 4.2 mm; length: 10 mm) were divided into 6 groups: short titanium base and zirconia (SZ), long titanium base and zirconia (LZ), short titanium base and lithium disilicate (SE), long titanium base and lithium disilicate (LE), short titanium base and polymer-infiltrated ceramic (SP), and long titanium base and polymer-infiltrated ceramic (LP). An adhesive resin cement was used to bond the restoration to the titanium base. The restoration was secured with titanium screw tightened to 30 Ncm by using a calibrated torque meter device. The specimens were exposed to thermocycling (5000 cycles at 5°C to 55°C), then cyclic loaded (120 000 cycles/50 N/1.6 Hz), where the load was placed vertically in mesial fossa of the restoration. After the loosening torque value of the abutment screw was measured by the torque meter device, the torque loss and its percentage were calculated. Two-way ANOVA, one-way ANOVA, and post hoc Tukey tests were used for statistical analysis of the data (α&#61;.05). The 2-way ANOVA test showed significant differences in loosening torque, torque loss and percentage of torque loss across the restorative material (P<.001), no significant difference across the height of titanium base (P&#61;.213) and no significant interaction (P&#61;.845) between restorative material and height of titanium base. Regarding the restoration type, 1-way ANOVA test showed significant difference (F ratio&#61;15.95, P<.001) in torque loss between groups. The mean torque loss value with monolithic zirconia was significantly higher than with lithium disilicate (P&#61;.039) and polymer-infiltrated ceramic (P<.001), respectively. Between the lithium disilicate and polymer-infiltrated ceramic, a significant difference (P&#61;.013) was also found. The restorative material had a major effect on the torque maintenance in hybrid-abutment-restoration supported by offset placed implant, while the titanium base abutment height had no influence on it. Compared to lithium disilicate and polymer-infiltrated ceramic materials, monolithic zirconia induced higher torque loss when used as hybrid-abutment-restoration.

Clinical, radiographic and patient-reported outcomes of zirconia and titanium implants in the posterior zone after 1 year of loading-A randomized controlled trial.

To assess the clinical, radiographic and patient-reported outcomes (PROMs) of posterior zirconia and titanium implants at 1 year of implant loading. Forty-two patients with two adjacent missing teeth were enrolled in a randomized controlled trial with a within-subject controlled design. Each patient received one zirconia (Zr) and one titanium (Ti) implant, with the mesial and distal positions randomized. The implant restoration consisted of multiple layered zirconia, with the buccal aspect veneered. In group Zr, the restoration was intraorally cemented onto the one-piece Zr implant, whereas in group Ti, the restoration was extraorally cemented onto the titanium base abutment and intraorally screw-retained onto the Ti implant. Examinations were performed following restoration delivery at baseline (BL) and at 1 year. Measurements included clinical parameters, radiographic outcomes (MBL) and PROMs. Bleeding on probing showed an increase from BL to 1 year (34 ± 30% for Zr; 25 ± 21% for Ti). MBL remained stable with minimal changes from BL to 1 year, measuring 0.1 ± 0.4 mm (mean ± SD) for Zr and -0.1 ± 0.7 mm for Ti. Veneering fractures were the most frequent technical complication and amounted to 17.5% in group Zr and 5% in group Ti (p = .100). Patients preferred Zr implants for their soft tissue color, with a significant difference in perception between patients and clinicians (p < .017). The study showed that both Zr and Ti implants had similar clinical outcomes, despite a high prevalence of mucositis and a few technical complications. Both implant types demonstrated stable marginal bone levels and similar patient-reported outcome measures.

Evaluation of Microstrain in the Regions Surrounding Morse Taper and External Hexagon Implants.

The aim of this study was to compare the Morse taper (MT) + titanium base (Ti-Base) abutment with the external hexagon (EH) + Ti-Base abutment by using the strain gauge method in the mesial, distal, and apical-buccal areas around these types of implants. This study investigated two groups, MT and EH, each comprising five polyurethane samples with a dental implant in the area of artificial tooth 15 (3.75 × 11.5 mm) of a dental manikin. The strain gauges were glued to the mesial, distal, and apical-buccal polyurethane areas of all samples in relation to the implant. Ti-Base nonangled abutments measuring 5.0 × 4.7 × 1.0 mm (DSP, Brazil) were installed on the implants in each group. Ten identical zirconia crowns were constructed by scanning and milling and were subsequently cemented onto the Ti-base abutments with calcium hydroxide cement. Then, an axial load of 100 N was applied to the occlusal region of the zirconia crowns, and strain gauge measurements were taken. Strain gauge data were assessed by a two-way analysis of variance (ANOVA) with "implant connection" and "strain gauge position" factors, followed by the Bonferroni test (p < 0.05). The MT group exhibited a statistically significant reduction in microstrain in the mesial and apical strain gauge measurements compared to the EH group. The MT group exhibited less microstrain in the mesial and apical areas of the polyurethane samples near the implant. Consequently, the MT connection was considered more biomechanically advantageous.

Multi-objective optimization of custom implant abutment design for enhanced bone remodeling in single-crown implants using 3D finite element analysis

The optimal configuration of a customized implant abutment is crucial for bone remodeling and is influenced by various design parameters. This study introduces an optimization process for designing two-piece zirconia dental implant abutments. The aim is to enhance bone remodeling, increase bone density in the peri-implant region, and reduce the risk of late implant failure. A 12-month bone remodeling algorithm subroutine in finite element analysis to optimize three parameters: implant placement depth, abutment taper degree, and gingival height of the titanium base abutment. The response surface analysis shows that implant placement depth and gingival height significantly impact bone density and uniformity. The taper degree has a smaller effect on bone remodeling. The optimization identified optimal values of 1.5 mm for depth, 35° for taper, and 0.5 mm for gingival height. The optimum model significantly increased cortical bone density from 1.2 to 1.937 g/cm3 in 2 months, while the original model reached 1.91 g/cm3 in 11 months. The standard deviation of density showed more uniform bone apposition, with the optimum model showing values 2 to 6 times lower than the original over 12 months. The cancellous bone showed a similar trend. In conclusion, the depth and taper have a significant effect on bone remodeling. This optimized model significantly improves bone density uniformity.

Material and abutment selection for CAD/CAM implant-supported fixed dental prostheses in partially edentulous patients - A narrative review.

Restorative material selection has become increasingly challenging due to the speed of new developments in the field of dental material science. The present narrative review gives an overview of the current indications for implant abutments and restoration materials for provisional and definitive implant-supported fixed dental prostheses in partially edentulous patients. For single implant restorations, titanium base abutments for crowns are suggested as an alternative to the conventional stock- and customized abutments made out of metal or zirconia. They combine the mechanical stability of a metallic connection with the esthetic potential of ceramics. For multiple-unit restorations, conical titanium bases especially designed for bridges are recommended, to compensate for deviating implant insertion axes and angulations. Even though titanium base abutments with different geometries and heights are available, certain clinical scenarios still benefit from customized titanium abutments. Indications for the definitive material in fixed implant restorations depend on the region of tooth replacement. In the posterior (not esthetically critical) zone, ceramics such as zirconia (3-5-Ymol%) and lithium-disilicate are recommended to be used in a monolithic fashion. In the anterior sector, ceramic restorations may be buccally micro-veneered for an optimal esthetic appearance. Lithium-disilicate is only recommended for single-crowns, while zirconia (3-5-Ymol%) is also recommended for multiple-unit and cantilever restorations. Attention must be given to the specific mechanical properties of different types of zirconia, as some feature reduced mechanical strengths and are therefore not indicated for all regions and restoration span lengths. Metal-ceramics remain an option, especially for cantilever restorations.

Fracture resistance of hybrid ceramic abutments with different restoration lengths: A pilot study.

In this pilot study, the fracture resistance of hybrid abutments with different restoration lengths was investigated. Sixteen monolithic zirconia restorations of an upper right incisor were designed to fit a titanium base abutment. Eight central incisors had a crown length of 8 mm (T1) and the other half a length of 12 mm (T2). All crowns were cemented on the titanium base using a resin cement. After cementation, the samples were placed in a thermocycler for 5000 cycles. Fracture strength was measured using a universal test machine. Deformations and fractures of the samples were investigated. The mean fracture resistance of T1 was 515 N (SD 96 N, 339-650) and 305 N (SD 57 N, 234-408) for T2 (p < 0.001). Both groups showed deformation of the titanium base, with no significant difference between both groups (p = 0.200). A difference in fracture type (p = 0.013) was observed, with significantly more screw fractures occurring in group T1 (p = 0.026). Within the limitations of this study, hybrid restorations with standard titanium base abutments can withstand forces that have been associated with chewing, irrespective of the crown length. However, the shorter crowns demonstrated more fatal fractures.

Fracture resistance of cement-retained lithium disilicate implant-supported crowns: Effect of material used for two-piece abutments.

This study compared the fracture strength of single lithium disilicate implant-supported crowns fabricated on two-piece abutments with various materials: ceramic-reinforced PEEK, zirconia, and lithium disilicate. Thirty-six implants were embedded in acrylic cylinders. A two-piece abutment and a crown were designed following a pre-operation scan for a maxillary left central incisor. The designed crown was used to fabricate 36 lithium disilicate crowns. The designed abutment was used to manufacture 36 abutments from 3 materials, 12 each: (A) zirconia; (B) lithium disilicate; and (C) ceramic-reinforced PEEK. Abutments were surface treated and bonded on the titanium base abutments with resin cement. Then, lithium disilicate crowns were bonded on the assigned abutments. Specimens were then subjected to dynamic loading for 1,200,000 cycles. The fracture strength (N) of the assembly was assessed using a universal testing machine. One-way ANOVA followed by multiple comparison tests was used to evaluate the effect of abutment material on the fracture strength of single implant-supported restorations at a significance of .05. The average fracture strength for the groups with zirconia, PEEK, and lithium disilicate two-piece abutments were 1362N ± 218N, 1235N ± 115N, and 1472N ± 171N, respectively. There was a significant (p < 0.05) difference in fracture strength among the groups. The lithium disilicate group had significantly higher fracture strength (p = 0.0058) than the group with PEEK; however, there was no significant (p > 0.05) difference between the other groups. Two-piece abutments restored with lithium disilicate crowns investigated in the study have the potential to withstand the average physiological occlusal forces in the anterior region.

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.

Rotational Load Fatigue Performance of a One-Size Implant- Abutment Connection System.

One-size implant-abutment (OSIA) connection systems have been developed for simplicity of clinical use and for a range of implant diameters. The aim of this in vitro study was to investigate the rotational load fatigue performance of different implant diameters and abutment platforms of an OSIA connection system. Narrow, regular and wide diameter implants were tested with Regular Base (RB/WB) abutments of an OSIA system (Straumann. BLX). Wide diameter implants were also tested with Wide Base (WB) abutments. This resulted in 4 test groups (n&#61;5): N-RB/WB (Narrow, 3.5mm, RB/WB abutment), R-RB/WB (Regular, 4.0mm, RB/WB abutment), W-RB/WB (Wide, 5.0mm, RB/WB abutment) and W-WB (Wide, 5.0mm, WB abutment). A rotational load fatigue machine applied a sinusoidally varying stress at an angle of 45o, producing an effective bending moment of 35Ncm at a frequency of 10 Hz in air at 20 oC. The number of cycles to failure was recorded. Results were evaluated using ANOVA. Failed specimens were examined with SEM to evaluate the failure mode. Pristine specimens were sectioned to examine the implant-abutment connection. All specimens in the 3 test groups with RB/WB abutments failed within the range of 558,750 cycles to 4,497,619 cycles, while the W-WB test group reached the upper limit of 5 million cycles without failure. Significant difference was found between abutment platforms (P < .001). There were no significant differences found for implant diameters (P &#61;.857). However, with increasing implant diameter, implant fracture was less common and the location of failure was more coronal and consistently at the level of the implant platform for the abutment, and at the screw neck. For wide diameter implants, WB abutments exhibited a superior fatigue performance than RB/WB abutments, and would be preferred in situations of high mechanical risk. Increasing implant diameter, when used with RB/WB abutments, did not improve fatigue performance due to the one-size prosthetic connection, but failures were less catastrophic, and coronally located, which may be advantageous in managing failures.

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.

Clinical performance and risk factors of all-ceramic screw-retained implant crowns in the posterior region based on a retrospective investigation.

Clinical data on all-ceramic screw-retained implant crowns (SICs) luted on titanium base abutments (TBAs) over more than 3 years are sparse. This study aimed to evaluate the clinical performance and potential risk factors for these restorations. Analysis took place based on the medical patient-records of three dental offices. Implant survival and prosthetic complications over time were evaluated. The study included SICs in premolar and molar regions made from monolithic lithium disilicate ceramic (M_LiDi) or veneered zirconia (V_ZiO) luted on a TBA documented over an observation time of at least 3 years. Survival and complication rates were calculated and compared by a log-rank test. Cox-Regressions were used to check potential predictors for the survival (p < .05). Six hundred and one crowns out of 371 patients met the inclusion criteria and follow-up period was between 3.0 and 12.9 (mean: 6.4 (SD: 2.1)) years. Over time, six implants had to be removed and 16 restorations had to be refabricated. The estimated survival rates over 10 years were 93.5% for M_LiDi and 95.9% for V_ZiO and did not differ significantly among each other (p = .80). However, V_ZiO showed significantly higher complication rates (p = .003). Material selection, sex, age, and implant diameter did not affect the survival of investigated SICs but crown height influences significantly the survival rate (hazard ratio, HR = 1.26 (95%CI: 1.08, 1.49); p = .043). Screw-retained SICs luted on TBAs that were fabricated from monolithic lithium disilicate ceramic or veneered zirconia showed reliable and similar survival rates. Increasing crown heights reduced survival over the years.

Comparison of the Effect of Implant Abutment Surface Modifications on the Retention of Implant-Supported Restorations.

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

Immediately versus early placed bone-level-tapered implants supporting all-ceramic crowns on titanium base abutments: 1-year radiographic and pink esthetic outcomes of a multicenter pilot RCT.

Aim of this study was to assess survival rates, radiographic, and pink esthetic outcomes of a bone-level-tapered (BLT) implant following immediate or early implant placement. Patients in need of tooth extraction and one implant in the anterior or premolar area were recruited in five centers. Patients were randomly assigned to the immediate or early placement protocol. Implants were restored with all-ceramic crowns cemented to titanium-base-abutments. Radiographic bone levels, implant stability quotient (ISQ), and pink esthetic outcomes were assessed. Data were analyzed descriptively. Level of significance was set at 0.05. Differences between groups were tested using Wilcoxon-signed-rank and Mann-Whitney-U test as nonparametric tests. A total of 60 patients received 60 BLT implants (Institut Straumann). At 12-months, 59 implants (98.3%) were osseointegrated. The mean distance from implant shoulder to first bone-to-implant contact was 0.15 ± 0.59 mm without significant differences between the groups. Median ISQ values increased from 75.5 to 78.5. A mean buccal recession of 0.1 ± 0.70 mm occurred with no difference between groups. The mean papilla height gain in both groups was 0.5 ± 1.47 mm mesially and 0.4 ± 1.36 mm distally. After 1 year, immediately and early placed BLT implants exhibit similar bone level changes, ISQ values, and pink esthetic outcomes. The present research contributes to the knowledge on clinical outcomes of immediately and early placed BLT implants restored with buccally microveneered ceramic single crowns out of two different ceramic materials. The research shows that similar esthetic and radiographic outcomes can be reached by means of immediate implant placement compared to the conventional early placement protocol. The improvement of esthetic soft-tissue parameters over time was shown for both implant placement protocols.

Influence of sterilization on the retention forces of lithium disilicate and polymer-infiltrated ceramic-network crowns bonded to titanium base abutments: An in-vitro study.

The aim of this study was to evaluate the effect of sterilization on the retention forces of lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns bonded to titanium base (Ti-base) abutments. Forty LD and 40 PICN crowns were milled and then bonded to 80 Ti-bases with two resin composite cements: Multilink Hybrid Abutment (mh) and Panavia V5 (pv) for a total of 8 groups (n = 10). Half of the specimens (test) underwent an autoclaving protocol (pressure 1.1 bar, 121°C, 20.5 min) and the other half not (control). Restorations were screw-retained to implants, and retention forces (N) were measured with a pull-off testing machine. The surfaces of the Ti-bases and the crowns were inspected for the analysis of the integrity of the marginal bonding interface and failure mode. Student's t-test, chi-square test, and univariate linear regression model were performed to analyze the data (α = 0.05). The mean pull-off retention forces ranged from 487.7 ± 73.4 N to 742.2 ± 150.3 N. Sterilized groups showed statistically significant overall higher maximum retention forces (p < .05), except for one combination (LD + mh). Sterilization led to an increased presence of marginal gaps and deformities compared to no-sterilization (p < .001), while no statistically significant relationship was found between failure mode and sterilization (p > .05). Sterilization may have a beneficial effect on the retention forces of LD and PICN crowns bonded to titanium base abutments, although it may negatively influence the integrity of the marginal bonding interface.

The influence of titanium-base abutment geometry and height on mechanical stability of implant-supported single crowns.

This study aimed to investigate the influence of titanium base (ti-base) abutment macro- and micro-geometry on the mechanical stability of polymer-infiltrated ceramic network (PICN) screw-retained implant-supported single crowns (iSCs). Twelve specimens per group were used, comprising six different implant/ti-base abutment combinations restored with PICN iSCs: Nb-T (gingival height [GH]: 1.5 mm, prosthetic height [PH]: 4.3 mm), CC (GH: 0.8 mm, PH: 4.3 mm), CC-P (GH: 0.8 mm, PH: 7 mm), Nb-V (GH: 1.5 mm, PH: 6 mm), St (GH: 1.5 mm, PH: 5.5 mm), and Th (GH: 0.5 mm, PH: 9 mm). The specimens underwent thermo-mechanical aging, and those that survived were subsequently subjected to static loading until failure. The data were analyzed using a one-way ANOVA test followed by Tukey post hoc test (α = .05). All specimens survived thermo-mechanical aging without complications, namely, visible cracks, debonding, or screw loosening. Th group demonstrated the highest strength values among all the groups, with significant differences compared to Nb-T (p < .05), CC (p < .001), and St (p < .001). Additionally, CC-P group exhibited significantly superior fracture strength results compared to CC (p < .05) and St (p < .05). The choice of ti-base, particularly prosthetic height, had a significant influence on fracture resistance of PICN iSCs. Nevertheless, the height or geometrical features of the ti-base did not exhibit a significant influence on the mechanical behavior of the iSC/ti-base assembly under thermomechanical loading, as all specimens withstood the aging without complication or failure.

Retention of zirconia crown to oxidized titanium base abutment: Experimental research.

To separate the crown from the titanium base abutment, by using heat, caused oxidization of the titanium base abutment. The effect of this procedure on the retention of a crown is unclear. To compare the resin bond strength and failure type between zirconia crowns and titanium base abutments utilizing four different surface treatments. Surface roughness and morphology of each surface treatment were also investigated. Forty titanium base abutments (Variobase®) were divided into four groups, 1. Control, 2. Air abraded, 3. Oxidized, and 4. Oxidized-air abraded. Oxidized and oxidized-air abraded groups were debonded from zirconia crowns using constant dry heat at 500 ˚C. For air abraded and oxidized-air abraded groups (after oxidization), the titanium base abutments were air abraded with Al3O2. After cleaning, one specimen of each group was investigated under a non-contact profilometer (50x), then the same samples were investigated under SEM at 25,300,500,1000 magnification and EDS at 30kV of accelerated voltage. All specimens were then cemented (RelyX Ultimate). After aging, with thermocycling under 5C° to 55C°,120 seconds dwell time for 5,000 cycles, bond strength was tested and statistical differences were calculated with One-way ANOVA (p-value <0.05) follow by Tukey test. All separated crowns and titanium base abutments were investigated under a light microscope (20x), using fisher's exact test for correlation of the failure types. There was a significant difference in the mean value of tensile bond strength among the control and test groups. Comparisons between control(237.6±46.3N) and oxidized(241.7±46.3N) showed statistically different values from air abraded(372.9±113.2N) when assembled using different surface treatments of the titanium-based abutments. (p-value<0.005) As for failure type, there were statistically significant differences between control versus air abraded, control versus oxidized-air abraded, oxidized versus air abraded, and oxidized versus oxidized-air abraded. (p-value<0.001) The titanium surface morphology shown from the profilometer and SEM was coordinated. Control (Ra 333.8nm) and oxidized (Ra 321.0nm) groups surfaces showed smooth, corrugated surfaces, meanwhile air abraded (Ra 476.0nm) and oxidized-air abraded (Ra 423.8nm) groups showed rough, rugged surfaces. Heat oxidization of titanium-based abutments did not adversely affect tensile bond strength or the failure mode and surface roughness between titanium base abutments and zirconia crowns. However, air abrasion of the titanium surface increased surface roughness and retentive strength. The titanium base abutments that were oxidized under heat treatment did not have an effect on crown retention. Thoroughly air abraded the titanium abutment prior to cementation can increase cement bond strength.

Positional transfer accuracy of titanium base implant abutment provided by two different scan body designs: an invitro study

BackgroundThe variabilities in design and material of scan bodies have a major role in the positional transfer accuracy of implants. The purpose of this invitro study was to compare the 3D transfer accuracy (trueness and precision) of titanium base (TB) abutment position provided by 2 different scan bodies: one-piece scan body (SB) in comparison to two-piece healing abutment and scan peg (HA-SP).MethodsA maxillary model with a dummy implant in the 2nd premolar (Proactive Tapered Implant; Neoss) was 3D printed and TB (Ti Neolink Mono; Neoss) was tightened on the implant and scanned by using a laboratory scanner (inEos X5; Dentsply Sirona) (reference scan). An SB (Elos Medtech) and an HA-SP (Neoss) were subsequently connected to the implant and were scanned 10 times each by using the same scanner (test scans). All the scans were exported as STL files and imported into CAD software where the TBs were formed. Test scans were superimposed on reference scans for transfer accuracy analysis using 3D metrology software (GOM Inspect; GOM GmbH) in terms of angular deviation in vertical and horizontal directions, linear deviation in each XYZ axis of TBs and total linear deviation in all axes. Statistical analysis was done using independent sample t test. When Levene’s test for equality of variances was significant, Welch’s t-test was used. (P value < 0.05)ResultsSignificant differences were found amongst the tested groups in both angular and linear deviation in terms of trueness with less deviation values for the SB group (P < 0.001). For the precision, significant differences were found amongst the tested groups in angular deviation in vertical direction with less deviation value for the SB group compared to HA-SP group (P < 0.001). However, no significant difference was found between the tested groups regarding the angular deviation in horizontal direction (P = 1.000). Moreover, significant differences were found amongst the tested groups in linear deviations with less linear deviations in XYZ axes for SB compared to HA-SP group (P = 0.020, < 0.001, = 0.010 respectively).ConclusionsSB showed less angular and linear deviation values in the 3D positional transfer of TB than HA-SP indicating higher degree of accuracy of SB.

Marginal Fit Evaluation of Zirconia Substructure Computer-Aided Design and Manufacturing (CAD/CAM) by Scanning Electron Microscope

Purpose. This in vitro study compared the vertical marginal discrepancy (MD) and absolute marginal discrepancy (AMD) between the zirconia substructure and titanium (Ti)-base abutment before and after cementation. Material and methods. An intraoral scanner (CEREC Omnicam scanner; Dentsply Sirona) was used to scan the dental model of missing tooth 36 and obtain a three-dimensional virtual model. It was designed and milled for 25 zirconia superstructures (inCoris ZI meso F2 L, Dentsply Sirona). The samples were cemented to Ti bases. The MD and AMD were measured for each sample by using a scanning electron microscope (SEM) before and after cementation. Results. The overall mean values of MD measurements before and after cementation were 14.12 μm and 20.28 μm, respectively. The overall mean values of AMD measurements prior to and after substructure cementation on the Ti base were 54.85 μm and 116.0 μm, respectively. ANOVA revealed significant differences in MD (p = 0.001) and AMD (p &lt; 0.001) before and after cementation. Conclusions. Significant differences were observed in MD and AMD values before and after cementation. The MD and AMD values were significantly lower before cementation than after cementation. The mean MD and AMD values were clinically acceptable.

Retention and marginal integrity of CAD/CAM fabricated crowns adhesively cemented to titanium base abutments - influence of bonding system and restorative material.

To assess the influence of bonding system and restorative material on the marginal integrity and pull-off forces of monolithic all-ceramic crowns bonded to titanium base (Ti-base) abutments. A total of 108 Ti-bases were sandblasted and divided into 9 experimental groups (n = 12 each) according to the combination of crown material (polymer-infiltrated ceramic network [PI], lithium disilicate [LD], and zirconia [ZI]) and bonding system (Multilink Hybrid Abutment [mh], PANAVIA V5 [pv], RelyX Ultimate [ru]), with their respective primers. After bonding the crowns to the Ti-base abutments, the restorations were screw-retained on implants and thermomechanically aged (1,200,000 cycles, 49 N, 1.67 Hz; 5°C to 55°C). Marginal integrity and bonding failure were evaluated under a light microscope, and pull-off forces (N) were calculated. Chi-square tests for marginal integrity, as well as one-way and two-way ANOVA for the pull-off forces, were applied (α = .05). PI presented higher marginal integrity than LD (P = .023). The bonding system pv revealed higher marginal integrity than mh (P = .005) and ru (P = .029). Differences in pull-off forces were found between restorative material and resin cement (P < .001), with the highest values for ZI + ru (598 ± 192 N), PI + pv (545 ± 114 N), LD + mh (532 ± 116 N), and PI + ru (528 ± 81 N). Specimens with marginal integrity revealed higher pull-off forces than those with alteration (P = .006). Specimens presenting bonding failures (micromovements) showed lower pull-off forces than those without bonding failures (P < .001). The tested CAD/CAM materials show favorable bonding performances with different bonding systems; nevertheless, a specific bonding system has to be recommended for each restorative material.