Hybrid Abutment Research Articles

Evaluation of Adhesion Protocol for Titanium Base Abutments to Different Ceramic and Hybrid Materials.

Scientific evidence regarding conditioning of different ceramic and hybrid materials and their bonding on titanium abutments is lacking. Titanium disks (Tritan) (N=450, n=15) were randomly cemented onto five different ceramic and hybrid materials, namely 1. Zenostar T, 2. Lava Ultimate, 3. IPS e.max CAD, 4. Vita Enamic multicolor and 5. G-ceram using three different cements, Panavia 21, TheraCem and Multilink hybrid abutment. Half of all specimens were thermocycled (5000 cycles, 5-55°C), while the other half were kept dry. Macro shear bond testing was conducted using a universal testing machine. Failure types were classified using a digital microscope. Data was statistically analyzed with three-way ANOVA and Tukey HSD post hoc tests. Both the ceramic (P⟨0.0001) and cement type(P⟨0.0001) significantly affected the shear bond strength(MPa), while thermocycling did not (P⟩0.05). The incidence of cohesive (50.34%) and adhesive failures (49.66%) were not significantly different. As for implant superstructures, when ceramics are bonded to titanium bases, the ceramic and cement type both have an impact on the bond strengths along with the conditioning and bonding protocols for each substrate. An equal affinity of the cements tested to the ceramic, hybrid materials and to titanium can be assumed. Combination of zirconia and TheraCem can be recommended for clinical use.

Fracture resistance of additive manufactured and milled implant-supported interim crowns

Statement of problemInterim dental prostheses can be fabricated by using subtractive or additive manufacturing technologies. However, the fracture resistance of implant-supported interim crowns fabricated by using vat-polymerization additive manufacturing methods remains unclear. PurposeThe purpose of this in vitro study was to evaluate the fracture resistance of anterior and posterior screw-retained implant-supported interim crowns fabricated by using subtractive and vat-polymerization direct light processing (DLP) additive manufacturing procedures. Material and methodsAn implant (Zinic Implant RP ∅4.0×10 mm) was placed in a 15×15-mm polymethylmethacrylate block. An implant abutment (ZiaCam, nonrotatory RP) was positioned on each implant. The virtual implant abutment standard tessellation language (STL) file provided by the manufacturer was imported into a software program (exocad v2.2 Valletta) to design 2 anatomic contour crowns, a maxillary right central incisor (anterior group) and a maxillary right premolar (posterior group). Each group was subdivided into 2 subgroups depending on the manufacturing method: milled (milled subgroup) and additive manufacturing (additive manufacturing subgroup). For the milled subgroup, an interim material (Vivodent CAD Multi) and a milling machine were used to fabricate all the specimens (N=40, n=10). For the additive manufacturing subgroup, a polymer interim material (SHERAprint-cb) and a DLP printer (SHERAprint 30) were used to manufacture all the specimens at a 50-μm layer thickness and 45-degree build orientation as per the manufacturer’s instructions. Then, each specimen was cemented to an implant abutment by using composite resin cement (Multilink Hybrid Abutment HO) as per the manufacturer’s instructions. A universal testing machine was used for fracture resistance analysis, and the failure mode was recorded. The Shapiro-Wilk test revealed that data were normally distributed. One-way ANOVA and Tukey multiple comparison were selected (α=.05). ResultsOne-way ANOVA revealed significant differences among the groups (P<.05). The anterior milled subgroup obtained a significantly higher fracture resistance mean ±standard deviation value of 988.4 ±54.8 N compared with the anterior additive manufacturing subgroup of 636.5 ±277.1 N (P<.001), and the posterior milled subgroup obtained significantly higher mean ±standard deviation of 423.8 ±68 N than the additive manufacturing subgroup of 321.3 ±128.6 N (P=.048). All groups presented crown fracture without abutment fracture. ConclusionsManufacturing procedures and tooth type influenced the fracture resistance of screw-retained implant-supported interim crowns. Milled specimens obtained higher fracture resistance compared with the DLP additive manufacturing groups. The anterior group was higher than the posterior group.

An evaluation of the stress effect of different occlusion concepts on hybrid abutment and implant supported monolithic zirconia fixed prosthesis: A finite element analysis

PURPOSEThe aim of this study is to evaluate the effects of canine guidance occlusion and group function occlusion on the degree of stress to the bone, implants, abutments, and crowns using finite element analysis (FEA).MATERIALS AND METHODSThis study included the implant-prosthesis system of a three-unit bridge made of monolithic zirconia and hybrid abutments. Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created using the original implant components. Two titanium implants, measuring 4 × 11 mm each, were selected. The loads were applied in two oblique directions of 15° and 30° under two occlusal movement conditions. In the canine guidance condition, loads (100 N) were applied to the canine crown only. In the group function condition, loads were applied to all three teeth. In this loading, a force of 100 N was applied to the canine, and 200-N forces were applied to each premolar. The stress distribution among all the components of the implant-bridge system was assessed using ANSYS SpaceClaim 2020 R2 software and finite element analysis.RESULTSMaximum stress was found in the group function occlusion. The maximum stress increased with an increase in the angle of occlusal force.CONCLUSIONThe canine guidance occlusion with monolithic zirconia crown materials is promising for implant-supported prostheses in the canine and premolar areas.

Bond strength between titanium and polymer-based materials adhesively cemented

The aim was to evaluate the bond strength between titanium and polymer-based materials for prosthetic restorations, cemented with different adhesive cement systems. Eight groups with 13 specimens in each group were included. Each specimen consisted of two parts: a cylinder of titanium resembling a titanium base, and a cylinder of one of two polymer-based materials Micro Filled Hybrid (MFH) or Telio CAD and cemented with one of four adhesive cement systems, namely Multilink Hybrid Abutment, Panavia V5, RelyX Ultimate and G-Cem LinkAce. The titanium was sandblasted with 50 µm Al2O3 and treated according to each cement manufacturer's recommendations. The polymer-based materials were pre-treated according to the manufacturer's instructions including sandblasting for MFH. After cementation, the groups were water stored for one day before thermocycling: 5000 cycles in 5–55 °C. A shear bond strength test was performed (crosshead speed 0.5 mm/min) and data was analysed with one-way ANOVA, Tukey's test. Telio CAD cemented with Panavia V5 and G-Cem LinkAce showed significantly lower bond strength compared to all other groups, due to spontaneous debonding. The highest numerical bond strength was found in the group of MFH cemented with RelyX Ultimate or with G-Cem LinkAce. Generally, the Telio CAD groups showed lower bond strength values than the MFH groups. The conclusions are that pre-treatment methods and choice of cement system are of importance for polymer-based materials for prosthetic restorations. The bond strength is adequate for provisional cementation irrespective of cement system when pre-treating by sandblasting, but cement dependent without sandblasting.

Bond strength of zirconia- or polymer-based copings cemented on implant-supported titanium bases – an in vitro study

Purpose To evaluate the bond strength between polymer-based copings and zirconia copings as positive control, cemented on implant-supported titanium bases with different adhesive cement systems. Moreover, to evaluate if airborne-particle abrasion of polymethylmetacrylate (PMMA) would enhance the bond strength. Methods Four groups of different materials were used to fabricate the copings, 30 in each group: airborne-particle abraded milled zirconia (TAZirconia, control group), milled PMMA (TPMMA), airborne-particle abraded milled PMMA (TAPMMA) and 3 D-printed micro filled hybrid resin (TAMFH). Each group of copings was cemented on titanium bases by three different adhesive cement systems, 10 each: Multilink Hybrid Abutment, Panavia V5, RelyX Ultimate. The specimens were stored dry at room temperature for 24 h, subjected to thermocycling for 5000 cycles followed by evaluating the bond strength by tensile strength test. Results TPMMA and TAPMMA cemented with Multilink Hybrid Abutment showed statistically significant lower bond strength in comparison to TAZirconia and TAMFH. No difference was observed between the latter two. TPMMA, TAPMMA and TAMFH had a statistically significant lower bond strength compared to the control group when cemented with Panavia V5. TPMMA and TAPMMA cemented with Rely X Ultimate showed statistically significant lower bond strength in comparison to the control group. Conclusion Almost all experimental groups, except 3 D-printed MFH, performed inferior than the positive control group where the highest bond strength was reported for the cementation of zirconia copings cemented with Panavia V5 or Rely X Ultimate. Airborne-particle abrasion did not improve the bond strength of the PMMA, except when Multilink Hybrid Abutment was used.

Influence of butt joint connections with long guiding areas on the stability of single crowns and 3-unit bridges - an in-vitro-study.

Purpose The aim of this study was to evaluate the stability of single crowns and 3-unit bridges in relation to the implant-abutment complex with and without tube in tube connection.Methods 60 specimens with a total of 90 implants (diameter 3.8 mm) were fabricated and distributed into 4 groups: CST (Crown with short tube), CLT (crown with long tube), BNT (Bridge without tube) and BLT (bridge with long tube). All superstructures consisted of one-piece hybrid abutment restorations out of monolithic zirconia, bonded on prefabricated titanium bases and were directly screwed into the implants. Specimen underwent artificial aging (2.000.000 cycles, 120 N, 30° off axis) and were subsequently loaded in an universal testing machine at an angle of 30° until failure. The specimens were examined for damage during and after artificial aging.Results During artificial aging, one test specimen of group CLT and two test specimens of group BNT failed. The average failure load was 498.8 (± 34.4) N for CLT, 418.8 (± 41.5) N for CST, 933.1 (± 26.2) N for BLT and 634.4 (± 29.0) N for BNT, with a statistical differences (p ˂ 0.001) between the crown and bridge groups. All tested samples exhibited macroscopic deformations at the implant shoulder, which were more pronounced in the specimens without a tube in tube connection.Conclusions Single crowns and 3-unit bridges with a long tube in tube connection showed significantly higher fatigue fracture strength compared to restorations with short or without tube in tube connection.

Mechanical Fatigue Analysis of PEEK as Alternative to Zirconia for Definitive Hybrid Abutments Supporting All-Ceramic Crowns.

The aim of this study was to inspect the mechanical fatigue behavior of an implant-supported restorative system using polyether ether ketone (PEEK) and yttria partially stabilized zirconia polycrystals (YZ) as materials for customized definitive implant-supported hybrid abutments, supporting two types of all-ceramic restorations: translucent zirconia (TZ) and lithium disilicate (LD) monolithic crowns. Forty Morse taper implants were included in epoxy resin. Titanium intermediary abutments were placed, and the specimens were randomly allocated into four groups (n = 10) according to the customized hybrid abutment material (PEEK or YZ) and the monolithic crowns (TZ or LD) representing a maxillary central incisor crown. The specimens were subjected to a mechanical fatigue test (step-stress analysis) by means of an initial 200-N load for 5,000 cycles and subsequent increase of 50 N (step-size) at each 10,000 cycles, until failure occurred. The load at failure and number of cycles until failure were recorded; survival probabilities and specimen displacement were calculated for each step. The failure pattern was evaluated, and the Weibull modulus was obtained for each condition. Fatigue of both types of crowns was not influenced by the abutment material (LD-PEEK = LD-YZ; TZ-PEEK = TZ-YZ). In the PEEK abutment, the values obtained in the LD and TZ crowns showed no statistical difference; however, in the YZ abutment, the TZ crown presented a load at failure value that was statistically higher than that for LD. Failure pattern analysis revealed a higher prevalence of crown fracture for LD groups, while screw/implant platform fractures were shown for TZ groups. YZ and PEEK hybrid abutments promoted similar fatigue levels regardless of the crown materials, TZ crowns promoted a higher fatigue level than LD ones when associated with YZ abutments, and LD crowns promoted a similar fatigue level to TZ ones when associated with PEEK custom abutments. Higher prevalence of crown fractures was shown for LD and screw/implant platform fractures for TZ groups.

Effect of Thermomechanical Loading on the Cementation Interface of Implant-Supported CAD/CAM Crowns Luted to Titanium Abutments.

To investigate the effect of aging on the morphology of the interface between monolithic implant crowns and standardized titanium base abutments. Four groups of hybrid abutment crowns differing in restorative material (lithium disilicate [LD] or polymer-infiltrated ceramic network [PICN]) and in fabrication procedure of the interfacial zone for luting to a titanium abutment (milled during CAD/ CAM procedure [M] or prefabricated [P]) were formed: LDS-M, LDS-P, PICN-M, and PICN-P (n = 10 each). The morphology of the crown-abutment interface was examined before and after artificial aging using scanning electron microscopy. The total gap length per specimen was measured at both time points, and intergroup (Kruskal-Wallis [KW]) plus pairwise (Wilcoxon Mann-Whitney [WMW]) comparisons were performed (α = .05). Before aging, statistically significant differences in gap length were identified among groups (KW: P = .0369) for PICN-P > LDS-P (WMW: P = .0496) and LDS-M > LDS-P (WMW: P = .0060). The effect of aging among the groups, expressed as an increment of total gap length, was 50% in LDS-M, 30% in LDS-P, 20% in PICN-M, and 30% in PICN-P. After aging, the statistically significant differences in gap length identified among groups (KW: P = .0048) were for PICN-P > LDS-P (WMW: P = .0134); LDS-M > PICN-M (WMW: P = .0204); PICN-P > PICN-M (WMW: P = .0486); and LDS-M > LDS-P (P = .0022). However, comparison of the difference in gap length from before to after aging among the groups was not statistically significant (KW: P = .3549). The cementation interfaces of CAD/CAM crowns on standardized titanium base abutments demonstrated a high percentage of gaps before and after thermomechanical loading. The composition of the restorative material and the nature of the interface influenced the interfacial gap dimension.

Crestal bone loss around tissue level implants with platform matching abutments versus bone level implants with conical/platform switched abutments in the posterior mandible: a comparative study

BackgroundMany factors play a role in the long-term survival of osseointegrated dental implants. Among these, the preservation of crestal bone remains to be the key principal. The aim of this comparative study was to assess crestal bone loss (CBL) between tissue-level implants restored with platform matching abutments and bone-level implants restored with conical/platform switched hybrid abutments in the posterior molar region.ResultsAll implants in both groups showed a 100% survival and success rate at 1 year. Mean CBL for group I was 0.8 mm (SD 0.85), and mean CBL for group II was 0.18 mm (SD 0.48). There was a statistically significant difference between the CBL in both groups (p < 0.001). The highest mean value was found in the tissue level group, while the lowest mean value was found in the bone level group.ConclusionWithin the limitations of the sample size of this study, both implant designs showed minimal CBL at 1-year post-loading. Bone level implants with a platform switched conical hybrid connection showed less CBL compared to tissue level implants.

Pink and white esthetic scores of polymer-infiltrated-ceramic-network and lithium disilicate implant hybrid abutment crowns: Randomized clinical trial

Objective: The aim of this study was to evaluate the effect of polymer-infiltrated-ceramic-network hybrid abutment crown on pink and white esthetics in comparison with lithium disilicate. Materials and methods: Eighteen patients requiring single unit implant restorations in the maxillary esthetic zone were enrolled in the study. Each patient received a single screw-retained hybrid abutment crown of either lithium disilicate (IPS e.max CAD) or polymer-infilitrated ceramic network (VITA ENAMIC) and was followed up for 6 months. The pink and white esthetics were evaluated at 0, 3 and 6 months timepoints using PES/WES index. Results: Regarding the combined PES/WES and the PES, no statistically significant difference was found between IPS e.max CAD and VITA ENAMIC hybrid abutment crowns at any timepoint. However, regarding the white esthetic score, a statistically significant difference was found between the two groups, favouring IPS e.max CAD. Conclusion: Within limitations of this clinical study, it could be concluded that IPS e.max CAD hybrid abutment crowns can yield satisfactory pink and white esthetic outcomes, when performed in well selected cases. VITA ENAMIC hybrid abutment crowns can yield clinically acceptable cumulative pink and white esthetic scores, however single elements of white esthetics, such as color, surface texture, translucency and characterization are significantly threatened by time.

Effect of airborne-particle abrasion of a titanium base abutment on the stability of the bonded interface and retention forces of crowns after artificial aging

Statement of problemPublished data have shown that a mechanical surface treatment of titanium surfaces increases bonding potential. However, most of the studies are based on shear or tensile tests performed on flat-surfaced specimens and do not take into consideration the retention given by the titanium base (ti-base) axial walls and the thermomechanical loading seen in a clinical setting. PurposeThe purpose of this in vitro study was to evaluate the influence of different airborne-particle abrasion (APA) methods of the ti-base surface on the stability of the bonded interface and retention forces between these titanium bases and lithium disilicate crowns after thermomechanical aging. Material and methodsSixty internal connection implants (Conelog) were restored with lithium disilicate crowns and bonded to the corresponding ti-bases (Conelog). The ti-bases were divided into 4 groups (n=15), 3 experimental groups applying different APA methods, 30-μm silica-modified Al2O3 particles (CoJet) (30-SiO-AlO), 50-μm Al2O3 (Cobra Aluoxyd) (50-AlO), 110-μm silica-modified Al2O3 particles (Rocatec Plus) (110-SiO-AlO), and 1 control group (NoT). Ti-bases were airborne-particle abraded (10 seconds, 0.25 MPa at a 10-mm distance) under standardized conditions in a custom-made APA device. All crowns were cemented with a resin cement (Multilink Hybrid Abutment). After aging (1 200 000 cycles, 49 N, 1.67 Hz; 5 °C-55 °C, 120 seconds), all specimens were assessed for the presence of bond failures by optical microscopy (×50). The retention forces (N) were tested by using a pull-off test (0.5mm/min). Modes of failure were classified (Type 1, 2, or 3). An additional ti-base representing each group was prepared for surface roughness (μm) calculation (Ra, Rc, Rz) with a noncontact laser profilometer, and representative scanning electron microscope (SEM) images were recorded (×1000). Chi-squared tests were performed to analyze the bonded interface failure and modes of failure, and a Kruskal-Wallis test was selected to evaluate retention force values (α=.05). ResultsThe percentages of bonding failure after aging were 73.3% (NoT), 40% (30-SiO-AlO), 6.7% (50-AlO), and 40% (110-SiO-AlO). The stability of the bonded interface was influenced by the APA method applied (P<.05). Mean ±standard deviation retention force values varied from 206.3 ±86.3 N (NoT) to 420 ±139.5 N (50-AlO), and the differences between these 2 groups were significant (P<.05). Modes of failure were predominantly Type 2 (30-SiO-AlO; 50-AlO; 110-SiO-AlO) and Type 3 (NoT). ConclusionsAirborne-particle abrasion of the titanium surface increased the bond stability and retention forces between the ti-base and the respective crown. The use of 50-μm Al2O3 provided the most stable bonded interface among the different treatments.

Temporary Implant-Supported Single Crowns Using Titanium Base Abutments: An In Vitro Study on Bonding Stability and Pull-out Forces.

To evaluate the effect of cementation protocols on the bonding interface stability and pull-out forces of temporary implant-supported crowns bonded on a titanium base abutment (TiB) or on a temporary titanium abutment (TiA). A total of 60 implants were restored with PMMA-based CAD/CAM crowns. Five groups (n = 12) were created: Group 1 = TiB/SRc: crown conditioned with MMA-based liquid (SR Connect, Ivoclar Vivadent); Group 2 = TiB/50Al-MB: crown airborne particle-abraded with 50-μm Al2O3 and silanized (Monobond Plus, Ivoclar Vivadent); Group 3 = TiB/30SiOAl-SRc: crown airborne particle-abraded with 30-μm silica-coated Al2O3 (CoJet, 3M ESPE) and conditioned with MMA-based liquid (SR Connect); Group 4 = TiB/30SiOAl-MB: crown airborne particle-abraded with 30- μm silica-coated Al2O3 (CoJet) and silanized (Monobond Plus); and Group 5 = TiA/TA-PMMA: crown manually enlarged, activated, and rebased with PMMA resin (Telio Lab, Ivoclar Vivadent). Specimens in the TiB groups were cemented using a resin cement (Multilink Hybrid Abutment, Ivoclar Vivadent). After aging (120,000 cycles, 49 N, 1.67 Hz, 5°C to 55°C, 120 seconds), bonding interface failure was analyzed (50x). Pull-out forces (N) (0.5 mm/minute) and modes of failure were registered. Chi-square and Kruskal-Wallis tests were used to analyze the data (α = .05). Bonding failure after aging varied from 0% (Group 5) to 100% (Groups 1, 2, and 4) (P < .001). Mean pull-out force ranged between 53.1 N (Group 1) and 1,146.5 N (Group 5). The pull-off forces were significantly greater for Group 5 (P < .05), followed by Group 3 (P < .05), whereas the differences among the remaining groups were not significant (P > .05). The cementation protocol had an effect on the bonding interface stability and pull-out forces of PMMA-based crowns bonded on a titanium base. Airborne particle abrasion of the crown internal surface and conditioning it with an MMA-based liquid may be recommended to improve retention of titanium base temporary restorations. Yet, for optimal outcomes, conventional temporary abutments might be preferred.

Qualitative and Semi-Quantitative Assessment of Processing-Related Surface Contamination of One- and Two-Piece CAD/CAM Abutments before and after Ultrasonic Cleaning.

Manufacturing processes of custom implant abutments may contaminate their surfaces with micro wear deposits and generic pollutants. Such particulate debris, if not removed, might be detrimental and provoke inflammatory reactions in peri-implant tissues. Although regulatory guidelines for adequate cleaning, disinfection, or sterilization exist, there does not appear to be a consistent application and data on the amount and extent of such contaminants is lacking. The aim of the present in vitro study was to evaluate the quality and quantity of processing-related surface contamination of computer-aided design/computer-aided manufacturing (CAD/CAM) abutments in the state of delivery and after ultrasonic cleaning. A total of 28 CAD/CAM monotype and hybrid abutments were cleaned and disinfected applying a three-stage ultrasonic protocol (Finevo protocol). Before and after cleaning, the chemical composition and the contamination of the abutments were assessed using scanning electron microscopy (SEM), dispersive X-ray spectroscopy (EDX), and computer-aided planimetric measurement (CAPM). In the delivery condition, monotype abutments showed a significantly higher amount of debris compared to hybrid abutments (4.86 ± 6.10% vs. 0.03 ± 0.03%, p < 0.001). The polishing process applied in the laboratory after bonding the hybrid abutment components reduces the surface roughness and thus contributes substantially to their purity. The extent of contamination caused by computer-aided manufacturing of custom abutments can be substantially minimized using a three-stage ultrasonic protocol.

The Use of Angulated Screw Channel Abutment System for Anterior Single-Implant Restorations: A Clinical Report

The purpose of this clinical report is to explain the use and advantages of hybrid abutment crowns supported by ti-base abutments with Angulated Screw Channel (ASC) for anterior single-implant restorations. ASC system abutments have recently released to market as a solution of visible screw access problem in the esthetic zone. Moreover, using hybrid abutment consists of ti-base abutment with ASC system and esthetic materials may be a new method to combine esthetic and mechanical strength advantages for anterior single implant restorations. The use of ASC system with hybrid abutment crown design may allow clinicians to obtain optimal esthetics and mechanical strength in the case of over-angulated implants.

Survival Probability, Weibull Characteristics, Stress Distribution, and Fractographic Analysis of Polymer-Infiltrated Ceramic Network Restorations Cemented on a Chairside Titanium Base: An In Vitro and In Silico Study.

Different techniques are available to manufacture polymer-infiltrated ceramic restorations cemented on a chairside titanium base. To compare the influence of these techniques in the mechanical response, 75 implant-supported crowns were divided in three groups: CME (crown cemented on a mesostructure), a two-piece prosthetic solution consisting of a crown and hybrid abutment; MC (monolithic crown), a one-piece prosthetic solution consisting of a crown; and MP (monolithic crown with perforation), a one-piece prosthetic solution consisting of a crown with a screw access hole. All specimens were stepwise fatigued (50 N in each 20,000 cycles until 1200 N and 350,000 cycles). The failed crowns were inspected under scanning electron microscopy. The finite element method was applied to analyze mechanical behavior under 300 N axial load. Log-Rank (p = 0.17) and Wilcoxon (p = 0.11) tests revealed similar survival probability at 300 and 900 N. Higher stress concentration was observed in the crowns’ emergence profiles. The MP and CME techniques showed similar survival and can be applied to manufacture an implant-supported crown. In all groups, the stress concentration associated with fractographic analysis suggests that the region of the emergence profile should always be evaluated due to the high prevalence of failures in this area.

Artificial intelligence in fixed implant prosthodontics: a retrospective study of 106 implant-supported monolithic zirconia crowns inserted in the posterior jaws of 90 patients

BackgroundArtificial intelligence (AI) is a branch of computer science concerned with building smart software or machines capable of performing tasks that typically require human intelligence. We present a protocol for the use of AI to fabricate implant-supported monolithic zirconia crowns (MZCs) cemented on customized hybrid abutments.MethodsThe study protocol consisted of: (1) intraoral scan of the implant position; (2) design of the individual abutment and temporary crown using computer-aided design (CAD) software; (3) milling of the zirconia abutment and the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the hybrid abutment and the temporary PMMA crown; (5) intraoral scan of the hybrid abutment; (6) CAD of the final crown with automated margin line design using AI; (7) milling, sintering and characterisation of the final MZC; and (8) clinical application of the MZC. The outcome variables were mathematical (quality of the fabrication of the individual zirconia abutment) and clinical, such as (1) quality of the marginal adaptation, (2) of interproximal contact points and (3) of occlusal contacts, (4) chromatic integration, (5) survival and (6) success of MZCs. A careful statistical analysis was performed.Results90 patients (35 males, 55 females; mean age 53.3 ± 13.7 years) restored with 106 implant-supported MZCs were included in the study. The follow-up varied from 6 months to 3 years. The quality of the fabrication of individual hybrid abutments revealed a mean deviation of 44 μm (± 6.3) between the original CAD design of the zirconia abutment, and the mesh of the zirconia abutment captured intraorally at the end of the provisionalization. At the delivery of the MZCs, the marginal adaptation, quality of interproximal and occlusal contacts, and aesthetic integration were excellent. The three-year cumulative survival and success of the MZCs were 99.0% and 91.3%, respectively.ConclusionsAI seems to represent a reliable tool for the restoration of single implants with MZCs cemented on customised hybrid abutments via a full digital workflow. Further studies are needed to confirm these positive results.

The Effect of Different Combinations of Surface Treatments and Bonding Agents on the Shear Bond Strength Between Titanium Alloy and Lithium Disilicate Glass-Ceramic

In order to obtain a more-natural esthetic prothesis, the use of hybrid abutments is becoming widespread in implant dentistry. The aim of this in vitro study was to assess the effects of different surface treatments, as well as the effects of different combinations of surface treatments and cementation protocols, on the shear bond strength between titanium alloy disks and lithium disilicate glass-ceramics. Forty titanium-alloy disks (4 × 6.6 mm) were fabricated using computer-aided designed/computer-assisted manufacturing, and an identical number of lithium disilicate glass-ceramic disks of similar sizes were fabricated by a heat-pressing technique to be attached to the titanium disks. The specimens from each material group were divided into two groups (n = 20 each) according to the surface treatment type: alumina airborne-particle abrasion or etching with hydrofluoric acid. Each group was then divided into two subgroups (n = 10) depending on the resin-cement type: Multilink Hybrid Abutment Cement (Ivoclar Vivadent) or PANAVIA SA Cement Plus (Kuraray). After thermocycling (5,000 cycles), a shear bond strength (SBS) test was conducted using a universal testing machine. Statistical analysis was performed by analysis of one-way analysis of variance and unpaired tests (P < .05). Statistically, the highest SBS values were obtained using airborne-particle abrasion. The surface treatment of titanium alloys by sandblasting led to a higher SBS compared to etching with hydrofluoric acid. The cement type also had a significant influence on SBS results.

Hibrid Abutment Kron Restorasyonlarda İmplant-Abutment Bağlantısının İmplant, Abutment ve Bazal Vidadaki Stres Dağılımı Üzerindeki Etkisinin İncelenmesi

Hibrid Abutment Kron Restorasyonlarda İmplant-Abutment Bağlantısının İmplant, Abutment ve Bazal Vidadaki Stres Dağılımı Üzerindeki Etkisinin İncelenmesi

Effect of reduced airborne-particle abrasion pressure on the retention of zirconia copings resin bonded to titanium abutments

Statement of problemThe optimal conditioning of zirconia is essential for a durable bond between zirconia copings and titanium inserts in 2-piece dental implant abutments. Low-pressure activation of the zirconia surface may be adequate for retention. PurposeThe purpose of this in vitro study was to evaluate the influence of airborne-particle abrasion (APA) of the zirconia surface with different pressures on the retention of zirconia copings bonded to titanium abutments. In addition, 2 luting systems were compared. Material and methodsComputer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings were divided into 3 groups (n=32): 0.1 MPa, 0.25 MPa, and not airborne-particle abraded surfaces with 50-μm alumina (Al2O3) particles. Compatible titanium abutments were airborne-particle abraded at a pressure of 0.25 MPa. All specimens were ultrasonically cleaned before bonding. Each group was divided into 2 subgroups (n=16) with different luting composite resins. A 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing self-adhesive luting composite resin (Panavia SA Cement Plus) and a conventional luting composite resin (Multilink Hybrid Abutment) in combination with a 10-MDP–containing universal primer (Monobond Plus) was compared. Two storage conditions were tested: in water (37 °C) for 3 days or 150 days with 37 500 thermocycles between 5 °C and 55 °C. After artificial aging, retention was measured in tension, and the failure modes were analyzed by using a light microscope and a scanning electron microscope. Statistical analysis was performed with 1-way ANOVA and the Games-Howell test for post hoc analysis (α=.05). ResultsThe mean retention of the airborne-particle abraded groups ranged from 576.0 N to 1049.3 N after 150 days of water storage and 37 500 thermocycles. No significant difference in bond strength was found between the 2 luting composite resin groups with airborne-particle abraded zirconia surfaces after 150 days (P<.05). Both bonding systems provided durable bond strength after 3 and 150 days. Failure mode was mainly cohesive at the titanium surfaces and predominantly adhesive at the zirconia surfaces. The retention was significantly higher if APA was used versus no APA (P<.05), while the APA pressure used made no significant difference. ConclusionsThe APA of zirconia copings at a pressure of 0.1 MPa in combination with 10-MDP–containing luting composite resins and primers is adequate for the durable bonding of zirconia copings to titanium inserts.

Influence of Different Cleaning Procedures on Tensile Bond Strength Between Zirconia Abutment and Titanium Base.

To investigate the tensile bond strength between zirconia abutments and titanium bases, luted with two different resin composite cements, after different cleaning procedures. Zirconia abutments and titanium bases were luted with either a DMA/HEMA-based cement (n = 80; Multilink Hybrid Abutment, Ivoclar Vivadent) or a Bis-GMA/TEGDMA-based cement (n = 80; Panavia V5, Kuraray Noritake). The adhesive gap of half of the specimens was polished (n = 40 per resin composite cement). Four separate specimens underwent roughness measurements and scanning electron microscopy. The specimens were divided into four groups (n = 10 per subgroup): (1) not cleaned, (2) cleaning in an ultrasonic bath, (3) cleaning in an autoclave, and (4) treatment with low-pressure plasma. The specimens were thermocycled (20,000×, 5°C/55°C), tensile bond strength was tested, and fracture types were analyzed. Data were examined using the Kolmogorov-Smirnov test, univariate ANOVA with additional partial eta-squared (ηp2), and the Mann-Whitney U test. The defined level of significance was adjusted by Bonferroni correction (P < .003). The tensile bond strength of specimens luted with the DMA/HEMA-based cement was higher than that of specimens luted with the Bis-GMA/TEGDMA-based cement. The polishing step and the cleaning procedures showed no impact on tensile bond strength results. Specimens luted with the DMA/HEMA-based cement presented more cohesive fractures, whereas specimens luted with the Bis-GMA/TEGDMA-based cement presented themselves with more fractures of the interface between the resin composite cement and zirconia abutment. Ra values showed a decline in roughness after polishing for both resin composite cements. As the DMA/HEMA-based cement showed higher tensile bond strength values, the usage of this resin composite cement for luting implant abutments to titanium bases can be recommended. Neither polishing nor the use of different cleaning procedures had an impact on tensile bond strength.