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PURPOSE: 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. MATERIALS AND METHODS: 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=.05). RESULTS: 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=.213) and no significant interaction (P=.845) between restorative material and height of titanium base. Regarding the restoration type, 1-way ANOVA test showed significant difference (F ratio=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=.039) and polymer-infiltrated ceramic (P<.001), respectively. Between the lithium disilicate and polymer-infiltrated ceramic, a significant difference (P=.013) was also found. CONCLUSION: 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.

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OBJECTIVE: To assess the clinical, radiographic and patient-reported outcomes (PROMs) of posterior zirconia and titanium implants at 1 year of implant loading. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

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PURPOSE: To retrospectively evaluate the long-term clinical, technical, biological, and esthetic outcomes of implant supported single zirconia crowns (ISCs) intraorally cemented to Ti-base hybrid-abutments up to 16 years after placement. MATERIALS AND METHODS: A total of 63 ISCs (Xive S, Camlog Screw Line, Replace Select TC NP, Branemark MK II, and 3i Osseotite) were evaluated in 36 patients at two different centers. Original Ti-bases were selected and zirconia meso structures and zirconia crowns were designed using CAD/CAM software and then milled from partially stabilized zirconia blocks. After the meso structures were cemented extraorally onto the Ti-bases, the ceramic crowns were intraorally luted to the hybrid abutments. The Ti-base ISC restorations were followed up for up to 16 years, and their clinical, biological, and esthetic outcomes were recorded at distinct time points (T1; T2) at three-year intervals. RESULTS: 36 patients (18 men, 18 women) received 32 ISCs in the anterior region and 31 in the posterior region of the maxilla and mandible. The mean follow-up of the Ti-base ISCs was 6.93 ± 2.60 years. The mean follow-up of the implants amounted to 8.11 ± 3.26 years. No implants were lost during follow-up, resulting in a cumulative implant survival rate of 100%. Abutment screw loosening was observed in two ISCs after one year in service. The overall cumulative restorative survival rate of the Ti-base restorations reached thus 96.83%. At T2 follow-up 24% of the ISCs exhibited an increase in PD despite maintaining clinically healthy peri-implant tissue. An 11% increase in BOP and a 3.17% decrease in PI were recorded. Despite spectrophotometrically measured ΔE values indicating visible discoloration of some restorations and their peri-implant soft tissue, a low incidence of esthetic complications was observed with an average PES/WES score of ≥ 12. No correlation was found between PES (R = -0.25; p = 0.27) and WES (R = -0.18; p = 0.43) scores and digital shade determination. CONCLUSIONS: The results of the present retrospective, multicenter, cohort study indicate satisfactory clinical outcomes for intraorally cemented single zirconia crowns (ISCs) supported by Ti-base hybrid abutments. An overall esthetic superiority of Ti-base ISCs could not be confirmed.

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OBJECTIVES: 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. MATERIALS AND METHODS: 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). RESULTS: 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). CONCLUSIONS: 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.

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

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AIM: In this pilot study, the fracture resistance of hybrid abutments with different restoration lengths was investigated. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

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OBJECTIVES: 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. MATERIALS AND METHODS: 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). RESULTS: 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). CONCLUSIONS: 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.

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PURPOSE: The aim of this in vitro study was to assess the effects of using different cements and titanium copings designs on the retention of implant-supported fixed dental prostheses (IFDPs) using a pull-out test. MATERIALS AND METHODS: Fifty zirconia (ZirCAD; Ivoclar Vivadent) and 20 prepolymerized denture acrylic resin (AvaDent) rectangular (36 mm × 12 mm × 8 mm) specimens were milled to mimic the lower left segmental portion of the All-on-Four IFDPs. Cylindrical titanium copings (Variobase; Straumann) (V) were used in 2 prepolymerized denture acrylic resin groups (n = 10) while conical titanium copings (Straumann) (C) were used as a control group for zirconia with 4 groups using cylindrical titanium copings. Before cementation, the outer surfaces of all titanium copings and the intaglio bonding surface of prosthetic specimens were airborne-particle abraded. All specimens were cemented following the manufacturer's recommendations and instructions according to the experimental design. After artificial aging (5000 cycles of 5°C 55°C, dwelling time 20 s; 150 N, 1.5 Hz in a 37°C water bath), all specimens were subjected to retention force testing using a pull-out test using a universal testing machine and a custom fixture with a crosshead speed 5 mm/min. Modes of failure were classified as Type 1, 2, or 3. Retention force values were analyzed by the t-test for the prepolymerized denture acrylic resin specimen groups, and 1-way ANOVA and the Tukey test for the zirconia groups at α = 0.05. RESULTS: Mean and standard deviation retention force values varied from 101.1 ± 67.1 to 509.0 ± 65.2 N for the prepolymerized denture acrylic resin specimen groups. The zirconia groups ranged from 572.8 ± 274.7 to 1416.1 ± 258.0 N. There is no statistically significant difference in retention force values between V and C specimens cementing to zirconia with Panavia SA cement (Kuraray Noritake) (p = 0.587). The retention forces and failure modes were influenced by the cement used (p < 0.05). Modes of failure were predominantly Type 2 (mixed failure) and Type 1 (adhesive fracture from prosthetic materials) except for the quick-set resin group (Type 3, adhesive failure from coping). CONCLUSIONS: When bonding IFDPs onto titanium copings, quick-set resin provided significantly higher retention force for prepolymerized denture acrylic resin prostheses. Conical and cylindrical titanium copings performed similarly when cemented to zirconia with Panavia SA cement under the same protocol. The stability of the bonded interface and retention forces between zirconia prostheses and titanium copings varied from the cement used.

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PURPOSE: To compare the effect of different pre-cementation surface treatments and bonding protocols on the retention force of additively manufactured (AM) implant-supported interim crowns. MATERIAL AND METHODS: A total of 50 AM interim crowns (Temporary CB resin) were cemented on implant abutments. Five groups (n = 10) were established based on the different surface pre-treatments performed in the intaglio surface of the specimens: no surface pre-treatment (Group C or control), air-abraded with 50-µm aluminium oxide particles (Group AP), air-abraded with 50-µm aluminium oxide particles followed by the application of silane (Group AMP), silane (Group MP), and air-abraded with 30 µm silica-coated aluminum oxide particles followed by the application of silane (Group CMP). Each specimen was cemented into an implant abutment using a composite resin cement (Rely X Unicem2). Afterward, the specimens underwent retention testing with a Universal Instron machine. Pull-off forces (N) and modes of failure were registered. Statistical analysis was performed using Mann-Whitney U tests with Bonferroni corrections for multiple tests (α = 0.05). RESULTS: The median retention force values were 233.27 ±79.28 N for Group Control, 398.59 ±68.59 N for Group MP, 303.21 ±116.80 N for Group AMP, 349.31 ±167.73 N for Group CMP, and 219.85 ± 55.88 N for Group AP. The pull-off forces were significantly greater for Group MP, while the differences between the remaining groups were not statistically significant (P > 0.05). Group AP showed the lowest retention force values among all the groups. Failure modes after the pull-off testing were predominantly adhesive and substrate failure of the AM interim material. CONCLUSIONS: The surface treatment of the intaglio AM crown tested significantly influenced the retention force values measured. Pre-treatment with an MDP-containing silane improved the retentive force values computed, whereas pre-treatment with 50-µm Al2 O3 air-particle abrasion alone is not recommended prior to cementation on a titanium-based implant abutment.

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BACKGROUND: The 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). METHODS: A 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) RESULTS: Significant 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). CONCLUSIONS: SB showed less angular and linear deviation values in the 3D positional transfer of TB than HA-SP indicating higher degree of accuracy of SB.

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BACKGROUND: The purpose of the current study was to assess the impact of three esthetic CAD/CAM material, titanium base height and their interaction on the retention strength of a hybrid-abutment-crown. METHODS: A total of 42 hybrid-abutment crowns with identical external geometries were designed in CAD software to fit two different Ti-Base abutment heights (n = 42/abutment height): either short (S) with 4 mm (n = 21) or long (L) 7 mm (n = 21) height. Each main group was divided into 3 subgroups (n = 7), according to esthetic crown material, Zirconia (Z), Lithium disilicate (L) and Hybrid ceramic (V). A universal primer and an adhesive resin cement were used for bonding according to the manufacturer instructions. Artificial aging in form of water storage (30 days), chewing simulation (50,000-cycles, 49 N, 1.67 Hz) and thermal cyclic (5000 cycles at 5-55 °C) were applied, specimens were pulled-out under tension load in (N) using a universal testing machine. Two and one-way ANOVA and Post Hoc Tukey test were used for statistical analysis. RESULTS: Long lithium disilicate (LL) group showed the highest retention (738.7 ± 178.5) followed by short lithium disilicate (LS) group (688.6 ± 169.9). Meanwhile, short zirconia (ZS) showed the lowest retention strength (231.1 ± 86.9). CONCLUSION: CAD/CAM fabricated lithium disilicate hybrid-abutment-crown can be used instead of conventional crowns over implant abutment. Etchable ceramics are recommended as a material of choice for CAD/CAM fabricated hybrid-abutment-crowns instead of zirconia in terms of retention durability.

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PURPOSE: The aim of this review was to evaluate the survival rates of restorations utilizing titanium base abutments (TBA) for restoring single-unit implant prostheses. MATERIALS AND METHODS: This review was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. The focus question was: In patients who require the restoration of a single dental implant utilizing a titanium base abutment, what are the determining factors and outcomes relating to implant prosthesis prognosis and survival? A comprehensive search of databases (PubMed, EMBASE, and Cochrane Library) was conducted on 16 April 2023 and updated on 5 May 2023. Randomized clinical trials (RCT), retrospective studies and prospective studies, reporting on the use of TBA for single implant prostheses, were reviewed. A Cochrane collaboration risk of bias assessment analysis was performed for randomized clinical studies, and the Newcastle-Ottawa Scale tool was applied for non-randomized studies. A meta-analysis was performed on clinical trials reporting on survival rates of both TBA and other abutments. Other clinical studies, reporting on TBA only, were included for descriptive statistics. RESULTS: The search provided 1159 titles after duplicates were removed. Six RCTs were included to perform a meta-analysis and compare the survival of the TBA to other abutments [OR 0.74; 95% CI: 0.21-2.63, heterogeneity; I2 0%; p = .99]. Twenty-three prospective and retrospective studies fulfilled the criteria and were included in the meta-analysis after 12 months of function. A total of 857 single implant-supported prostheses fabricated with a TBA were included. TBA abutments have an estimate 98.6% survival rate after 1 year in function (95% CI: 97.9%-99.4%). The mean follow-up period was 31.2 ± 16.9 months. CONCLUSIONS: Single implant prosthesis restored with titanium base abutments showed favourable short-term survival rates.

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Digital dentistry has contributed to the evolution and simplification of dental implantology over the last decade. The incorporation of intraoral scanners, CBCT, 3D implant-planning software, and CAD/CAM systems makes prosthetically driven implantology a straightforward process. Such digital resources for treatment planning and execution, following evidence-based concepts, have the ability to improve the long-term esthetics and function of implant-supported restorations as well the long-term survival of dental implants. Dental implants are frequently considered as the first treatment option for replacing failing or missing teeth. However, their use in the esthetic zone remains a challenge for many clinicians. The present article provides clinical guidelines for ideal implant positioning employing computer-guided surgery and chairside CAD/CAM-fabricated provisional and definitive restorations with titanium (Ti)-bases for successful prosthetic outcomes, optimizing gingival architecture, and decreasing overall treatment duration. (Int J Comput Dent 2023;26(1):75-0; doi: 10.3290/j.ijcd.b3818287).

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OBJECTIVES: The objective of this study is to compare monolithic hybrid abutment crowns (screw-retained) versus monolithic hybrid abutments with adhesively cemented monolithic single-tooth crowns. MATERIALS AND METHODS: Twenty subjects in need of an implant-borne restoration were randomly assigned to receive either a cement-retained (CRR) or a screw-retained (SRR) implant-supported monolithic lithium disilicate (LS2 ) reconstruction. Each patient received a titanium implant with in internal conic connection. After osseointegration and second-stage surgery, healing abutments were placed for about 10 days. The type of restoration (CRR vs. SRR) was randomly assigned, and the restorations were manufactured of monolithic LS2 . Both types of restorations, CRR and SRR, were based on a titanium component (Ti-base) that was bonded to the abutment (CRR) or the crown (SRR). The follow-up period for all restoration was 36 months. Clinical outcome was evaluated according to Functional Implant Prosthetic Score (FIPS). Quality of live (OHIP) and patient's satisfaction were assessed using patient-reported outcome measures (PROMs). Primary endpoint was loss of restoration for any reason. Kaplan-Meier curves were constructed and log-rank testing was performed (p < .05). RESULTS: One restoration of group CRR failed after 6 months due to loss of adhesion between Ti-base and individual abutment. No further biological or technical failures occurred. Kaplan-Meier analysis showed no significant difference between both treatment options (p = .317). There was no statistically significant difference between both types of restoration, neither for FIPS, OHIP, treatment time nor patient satisfaction (p > .05). CONCLUSION: Monolithic hybrid abutment crowns (screw-retained) and monolithic hybrid abutment with adhesively cemented monolithic crowns using lithium disilicate showed no statistically significant difference for implant-based reconstructions in this pilot RCT setting.

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OBJECTIVES: To investigate the fracture strength of angulated hybrid abutments supporting anterior single crowns on narrow-diameter implants (NDIs). MATERIAL AND METHODS: Zirconia abutment with angulations of labial inclination 0° (TZ0Z), 15° (TZ15Z), 30° (TZ30Z) and palatal inclination 15° (TZ - 15Z) was designed on 3.3-mm titanium-zirconium (Ti-Zr) NDIs. Titanium abutment connected with Ti-Zr implant (TZ0T) and 0° zirconia abutment connected with pure titanium (Ti) implant (T0Z) were control groups. Thirty-six un-restored abutments and 36 abutments restored with highly translucent zirconia (HTZ) crowns were tested. Failure loads were compared among 6 groups, and bending moments were calculated for comparison between un-restored and restored abutments. RESULTS: Failure loads of un-restored abutments were affected by the abutment angle. Sixty-seven percent samples in TZ30Z and 83% samples in TZ - 15Z group fractured at the thinnest part of the zirconia abutment and exhibited lower failure load (p < .05). Failure loads of restored abutments were close to or exceeded the maximum bite force of anterior teeth, and no differences were found among six groups (p > .05). Except TZ15Z and TZ0T group, the bending moment increased with the crown construction, especially for TZ30Z and TZ - 15Z groups (p < .001). CONCLUSIONS: The fracture strength of hybrid abutments restored with HTZ crown on Ti-Zr NDIs exceeded the bite forces of anterior teeth for all the groups and were not affected by the abutment angle. CLINICAL RELEVANCE: In terms of fracture strength, Ti-Zr NDIs combined with angulated hybrid abutments and HTZ crowns can be used in the anterior region.

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The effects of different heights of ti-base abutments on the color of anterior screw-retained zirconia restorations fabricated using computer-aided design and computer-aided manufacturing (CAD-CAM) technologies may affect the optical clinical outcome. The purpose of this study was to measure and compare the color parameters of zirconia crowns in different shades on ti-base abutments. Identical specimens (N = 160) were milled to restore the screw-retained central maxillary incisor crown, using 5% mol yttria zirconia (5Y-TZP). The specimens were designed using computer design software to match 3.5 mm and 5.5-mm ti-base abutments and milled using one CAD-CAM technology. Specimens were divided into four main groups depending on zirconia shade (A1/0, A2/3, A3.5/4 and B2/3) and then assigned to two subgroups according to ti-base height. Color measurements in the CIELab coordinates were made using a spectrophotometer under room-light conditions. Color difference (ΔE*) values were calculated using the CIE76 and CIEDE2000 formula. Within the group of A0/1 and A2/3, for 5.5 mm abutment height, a significant difference was found between the means of colors ∆E00 and ∆Eab (p < 0.01). Using a 5.5 mm-height ti-base abutment may produce a clinically unacceptable outcome (ΔEab > 2) in A1/0 and A2/3 color groups.

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OBJECTIVES: To test and compare two types of implant systems restored with four monolithic polymer-based materials with regard to their bending moments (BM) before and after aging. METHODS: A total of 192 tissue-level implants (TRI Dental Implants) differing in the presence (TiB, Octa line, n = 96) or absence (NTiB, Matrix line, n = 96) of a titanium base were restored with mandibular right first molar crowns manufactured from composite (CC), polymer-infiltrated ceramic (VE), PMMA (PM) and a 3D printed resin (ND) (n = 24). Half of the specimens (n = 12) were loaded for 1,200,000 cycles (50 N, 1.3 Hz, TC: 5/55 °C, 6000×) and examined for failures. Fracture load was measured according to ISO standard 14801, BM was calculated, and fracture types were examined. Data were analyzed using parametric statistics (p < 0.05). RESULTS: No failures were observed after 600,000 cycles. After 1,200,000 cycles, wear traces were recorded in all groups except PM, VE and CC on TiB implants. In group CC on NTiB implants, three specimens were rated zero in BM testing as they showed fracture of the screw. Regarding BM, TiB implants exhibited higher values than NTiB implants with aged CC (p = 0.023), aged PM (p < 0.001), initial PM (p = 0.011) and initial VE (p < 0.001). No differences occurred among the implant types with initial CC, initial ND, aged ND and aged VE. With regard to initial BM values, NTiB implants showed higher values for ND and CC compared with PM and VE (p < 0.001). No differences in initial BM values were found for the tested materials on TiB implants (p > 0.116). When aged, restoration material had no impact on the BM values of NTiB implants (p ≥ 0.233). Aged TiB implants showed higher values in combination with CC than with ND (p = 0.001). PM and VE showed similar values as ND and CC. Artificial aging led to a decrease of BM within PM, CC and ND on NTiB implants and ND on TiB implants. The majority of failures after testing were characterized by crown fractures in two to four pieces. Fractures in more pieces with smaller fragments occurred primarily for ND. SIGNIFICANCE: The use of NTiB implants with the polymer-based materials tested can only be recommended for clinical use as interim prostheses. CC seems to show a positive effect on the BM. Clinical research investigating the in vivo behavior is necessary to confirm these findings.

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OBJECTIVES: The purpose of this in vitro study was to evaluate the influence of the ceramic thickness, cement shade, and airborne-particle abrasion of the titanium on the final color of titanium base cemented lithium disilicate glass-ceramic restorations. METHOD AND MATERIALS: In total, 144 lithium disilicate glass-ceramic disks of three thicknesses (0.5, 1.0, and 1.5 mm) were cemented to airborne-particle-abraded and non-airborne-particle-abraded titanium disks with six adhesive resin cements. The color measurements were performed with a clinical spectrophotometer. The mean and standard deviation of evaluated ΔE values were calculated. A three-way analysis of variance (ANOVA) was used for analyzing the data. Statistical analyses were computed with a significance level of α = .05 using a statistical software program (Minitab 17, Minitab). RESULTS: The 0.5- and 1-mm-thick ceramic specimens cemented with Panavia V5 Opaque showed the lowest ΔE values when cemented on both non-airborne-particle-abraded (5.62 ± 1.66, 3.15 ± 1.28) and airborne-particle-abraded (5.55 ± 0.86, 3.16 ± 0.49) surfaces, while the highest values were seen in the groups cemented with RelyX U200 A2 (29.22 ± 0.83, 17.23 ± 0.45) and Panavia V5 A2 (29.94 ± 1.17, 16.71 ± 0.44) on airborne-particle-abraded surfaces. For the 1.5-mm-thick ceramics, the lowest ΔE values were seen when Multilink MO 0 cement was used on non-airborne-particle-abraded surfaces (1.56 ± 0.29) and when Panavia V5 Opaque was used on airborne-particle-abraded surfaces (1.56 ± 0.66). The highest values were seen when RelyX U200 A2 (9.77 ± 1.13), PA2 (9.24 ± 0.25), and Multilink HO 0 (9.19 ± 1.33) were used on airborne-particle-abraded surfaces, and when Multilink HO 0 (9.61 ± 1.70) was used on non-airborne-particle-abraded surfaces. The 1-mm-thick ceramics cemented with Multilink HO 0 showed higher ΔE values (12.05 ± 1.99) for airborne-particle-abraded and non-airborne-particle-abraded (12.58 ± 1.06) than thinner (0.5 mm) or thicker (1.5 mm) ceramics. CONCLUSION: Thinnest ceramic superstructures resulted in the highest ΔE values. Cements that mask the underlying color reflect their own shade under thin superstructures. Airborne-particle abrasion of titanium surfaces increases the grayish reflectance if cement shade does not have the color masking ability.

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PURPOSE: Titanium bases are used frequently in daily practice for bonding to CAD/CAM abutments or crowns. Due to intimate contact between the adhesive gap of the titanium-base abutment and the peri-implant bone, the physical and chemical characteristics of the bonding material, or the gap itself, may affect peri-implant inflammatory reactions. The present study therefore aimed to examine the long-term effects of individualised abutments bonded to titanium bases on peri-implant health. MATERIALS AND METHODS: A total of 24 patients, each with one test and one control abutment, participated in the present prospective, single-blind, randomised controlled clinical trial. The test abutments were CAD/CAM titanium abutments bonded to titanium bases. As the control abutments were individualised, one-piece CAD/CAM titanium abutments were used. Clinical and radiographic parameters were assessed at abutment insertion and then on a yearly basis over the following 5 years. RESULTS: No significant differences in marginal bone level were observed between the titanium-base and one-piece abutments at any of the follow-up time points; however, when intragroup marginal bone levels were compared to the baseline values, significant differences were found at several follow-up time points. Intergroup differences were only found to be significant for pocket depth at the 4- (P = 0.006) and 5-year follow-ups (P = 0.024), favouring titanium-base abutments. CONCLUSIONS: Within the limitations of the present study, it appears that the peri-implant tissues of this specific patient cohort responded to titanium-base abutments in a rather similar manner to one-piece abutments over a 5-year period; however, no definitive conclusions can be drawn due to the low power of the present study.

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PURPOSE: The purpose was to investigate stress distribution among 4 different customized abutment types: titanium abutment (Ti), titanium hybrid-abutment-crown (Ti-Hybrid), zirconia abutment with titanium base (Zir-TiBase), and zirconia hybrid-abutment-crown with titanium base (Zir-Hybrid-TiBase). MATERIALS AND METHODS: To achieve this purpose, 4 types of abutment configurations were simulated. A static load of 200 N (vertical) and 100 N (oblique) were applied to the models. The volume average, maximum, and stress distribution of von Mises stress, including percentage difference, were analyzed with 3D finite element analysis. RESULTS: According to the volume average von Mises stress, the Ti and Zir-TiBase comparison group showed that the Zir-TiBase group dominantly generated the higher value at Ti-base (22.57 MPa) and screw (17.68 MPa). To evaluate the effect of the hybrid-abutment-crown on volume average von Mises stress by comparing the Ti-Hybrid and Zir-Hybrid-TiBase groups, it was revealed that the combination of abutment and crown in the Ti-Hybrid group generated the worst stress concentration at the screw (12.42 MPa), while in the Zir-Hybrid-TiBase group presented stress concentration at the implant (8.90 MPa). CONCLUSIONS: A titanium base improved stress distribution at implant in zirconia abutment with titanium base by absorbing stress itself. Customized titanium hybrid-abutment-crown and zirconia hybrid-abutment-crown with titanium base created concentrated stress at screw and implant; respectively. Both abutment types should be cautiously used and maintenanced regularly.

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