Finishing technique effect on strength of zirconia-reinforced lithium silicate ceramic.

The aim of this study was to evaluate the effect of two finishing techniques, glazing or polishing, in comparison with the as-cut condition, on the biaxial-flexural-strength (BFS) of a zirconia-reinforced lithium silicate ceramic (ZLS). Cylinders were milled from CAD/CAM blocks and sliced to obtain disc-shaped specimens (ISO6872:2015). Polished and glazed specimens were processed following the manufacturer's instructions. Thirty-three specimens were obtained for each condition and microstructural and BFS/fractographic characterizations were performed. BFS and roughness data were analyzed using Weibull statistics and ANOVA one-way with Tukey post-hoc test, respectively. While a rougher surface was observed for as-cut specimens, smoother surfaces were observed for polished and glazed ZLS at microscopical evaluation and confirmed through surface-roughness evaluation. X-ray spectra depicted a glass phase for all groups and characteristic metasilicate, lithium disilicate, and lithium phosphate peaks for the as-cut and polished specimens. Glazed specimens showed higher characteristic strength than polished and as-cut specimens, which did not differ significantly. While higher Weibull-modulus was observed for the polished than for the as-cut specimens, no statistically significant differences were noted between glazed and polished, and between glazed and as-cut specimens. ZLS presents higher strength when glazed, and polishing increases the structural reliability of the material relative to the as-cut condition. Both finishing techniques reduced surface roughness similarly.

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part II: Translational Potential of 3D-Printed Scaffolds for Defect Repair.

Computer-aided design/computer-aided manufacturing and 3-dimensional (3D) printing techniques have revolutionized the approach to bone tissue engineering for the repair of craniomaxillofacial skeletal defects. Ample research has been performed to gain a fundamental understanding of the optimal 3D-printed scaffold design and composition to facilitate appropriate bone formation and healing. Benchtop and preclinical, small animal model testing of 3D-printed bioactive ceramic scaffolds augmented with pharmacological/biological agents have yielded promising results given their potential combined osteogenic and osteoinductive capacity. However, other factors must be evaluated before newly developed constructs may be considered analogous alternatives to the "gold standard" autologous graft for defect repair. More specifically, the 3D-printed bioactive ceramic scaffold's long-term safety profile, biocompatibility, and resorption kinetics must be studied. The ultimate goal is to successfully regenerate bone that is comparable in volume, density, histologic composition, and mechanical strength to that of native bone. In vivo studies of these newly developed bone tissue engineering in translational animal models continue to make strides toward addressing regulatory and clinically relevant topics. These include the use of skeletally immature animal models to address the challenges posed by craniomaxillofacial defect repair in pediatric patients. This manuscript reviews the most recent preclinical animal studies seeking to assess 3D-printed ceramic scaffolds for improved repair of critical-sized craniofacial bony defects.

Ultrathin lithium disilicate and translucent zirconia crowns for posterior teeth: Survival and failure modes.

PURPOSE: To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra-translucent zirconia crowns for posterior teeth restorations. MATERIALS AND METHODS: Fifty-four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y-TZP (Zirconn Translucent, Vipi), and (3) 5Y-PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth-motion step-stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope. RESULTS: Beta (ß) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95-99) regarding 3Y-TZP and 5Y-PSZ groups (84% CB: 65%-93% and 79% CB: 37&-94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%-91%) was higher than 5Y-PSZ (20% CB: 4%-44%) and not significantly different from 3Y-TZP (54% CB: 32%-72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface. CONCLUSIONS: Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high-load bearing regions must be carefully evaluated. CLINICAL SIGNIFICANCE: Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre-molars. Their clinical indication in high-load requirement regions must be carefully evaluated.

Hydrofluoric acid concentration and etching time affect differently the microstructure and surface properties of pressed lithium disilicate glass ceramics.

OBJECTIVE: To evaluate the effect of different hydrofluoric acid concentrations and etching times on the surface, chemical composition and microstructure of lithium disilicate. MATERIAL AND METHODS: Ninety specimens of pressed lithium disilicate (LDS) were obtained (IPS e.max Press, Rosetta SP and LiSi Press). The specimens of each material were divided in two groups according to the hydrofluoric acid concentration: 5% and 10% (n = 15/group), and subdivided according to the etching time: 20, 40 and 60 s (n = 5/group). Crystalline evaluations and chemical composition were performed through x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDS), respectively. Microstructural analyses were performed by scanning electron microscope (SEM), surface roughness (Ra), and material thickness removal evaluation. Thickness removal and Ra data were analyzed by ANOVA and Tukey test (p < 0.05). RESULTS: XRD demonstrated characteristic peaks of lithium disilicate crystals, lithium phosphate and of a vitreous phase for all materials. EDS identified different compositions and SEM confirmed different surface responses to acid etching protocols. Material and etching time influenced Ra and material thickness removal (p < 0.05). CONCLUSION: Hydrofluoric acid concentration and etching time affect the surface characteristics of LDS differently. LiSi Press presented higher resistance to hydrofluoric acid etching compared to e.max Press and Rosetta SP. CLINICAL SIGNIFICANCE: Applying the appropriate etching protocol is pivotal to avoid excessive material removal and to prevent jeopardize the mechanical and optical properties of the material.

Reliability and lifetime of lithium disilicate, 3Y-TZP, and 5Y-TZP zirconia crowns with different occlusal thicknesses.

OBJECTIVES: To assess the probability of survival of crowns made with a 3Y-TZP, a 5Y-TZP, and a lithium disilicate. MATERIALS AND METHODS: CAD-CAM premolar crowns with occlusal thicknesses of 1.0 mm or 1.5 mm and cemented on a metal dye. Step-stress accelerated life testing (SSALT) was performed to access the use level probability Weibull curves and reliability were calculated for the completion of a mission of 100,000 cycles at 300 to 1200 N. RESULTS: All ceramics showed a high probability of survival (87-99%) at 300 N, irrespective of thickness. 3Y-TZP shows no significant decrease in the probability of survival up to 1200 N (83-96%). Lithium disilicate presented lower reliability than zirconia under the 600 N mission. 5Y-TZP showed lower reliability than 3Y-TZP at 1200 N. There was no significant difference in the Weibull modulus (3.23-7.12). 3Y-TZP had the highest characteristic strength (2483-2972 N), followed by 5Y-TZP (1512-1547 N) and lithium disilicate (971-1154 N). CONCLUSION: Zirconia ceramics have a high probability of survival (up to 900 N-load), while lithium disilicate survives up to 300 N load only, irrespective of the thickness (1.0 mm or 1.5 mm). CLINICAL RELEVANCE: The probability of survival of posterior crowns made with zirconia ceramics resists extreme loads while glass ceramics resist normal chewing loads. In addition, crowns with thinner occlusal face showed sufficient mechanical behavior.

Fiber-reinforced composite full-arch prosthetic reconstructions supported by three standard, short or extra-short implants: a two-center retrospective study.

OBJECTIVES: To evaluate the survival of implants and prostheses, and marginal bone level of fiber-reinforced composite implant supported fixed complete prostheses supported by 3 implants. MATERIALS AND METHODS: Patients with fiber-reinforced composite fixed prostheses supported by 3 standard-length, short or extra-short implants were included in this retrospective cohort study. Kaplan-Meier survival was computed for implants and prostheses. Univariate and multivariate Cox proportional hazard regressions, clustered by patient, were used to analyze bone level differences as a function of different study covariates. Linear regressions were used to investigate the relationship between distal extension lengths and bone levels. RESULTS: Forty-five patients with 138 implants were followed for up to 10 years after prosthesis insertion (mean 52.8; SD 20.5 months). Kaplan-Meier survival analysis showed overall survival rates of 96.5% for implants and of 97.8% for prostheses. The 10-year success rate for prostheses was 90.8%. Extra-short implants survived at similar rates to short and standard implants. Marginal bone levels surrounding implants remained stable over time, even showing slight bone gain on average (mean + 0.1 mm/year; SD ± 0.5 mm/year) Acrylic denture teeth, overdentures on the opposing arch, and implant placement in the posterior maxilla were correlated with bone gain. Screw retention, opposed to telescopic retention, was correlated with bone loss. Longer distal extensions were correlated with bone gain on the implants closest to the distal extensions. CONCLUSIONS: Fiber-reinforced composite fixed prostheses supported by only 3 implants, most of which were extra-short, presented high survival rates with stable bone levels. CLINICAL RELEVANCE: An encouraging prognosis can be expected for restoration of atrophic maxillary and mandibular arches, when restored with fixed fiber-reinforced composite frameworks with long distal extensions and supported on only 3 short implants.

Bone Tissue Engineering (BTE) of the Craniofacial Skeleton, Part I: Evolution and Optimization of 3D-Printed Scaffolds for Repair of Defects.

Bone tissue regeneration is a complex process that proceeds along the well-established wound healing pathway of hemostasis, inflammation, proliferation, and remodeling. Recently, tissue engineering efforts have focused on the application of biological and technological principles for the development of soft and hard tissue substitutes. Aim is directed towards boosting pathways of the healing process to restore form and function of tissue deficits. Continued development of synthetic scaffolds, cell therapies, and signaling biomolecules seeks to minimize the need for autografting. Despite being the current gold standard treatment, it is limited by donor sites' size and shape, as well as donor site morbidity. Since the advent of computer-aided design/computer-aided manufacturing (CAD/CAM) and additive manufacturing (AM) techniques (3D printing), bioengineering has expanded markedly while continuing to present innovative approaches to oral and craniofacial skeletal reconstruction. Prime examples include customizable, high-strength, load bearing, bioactive ceramic scaffolds. Porous macro- and micro-architecture along with the surface topography of 3D printed scaffolds favors osteoconduction and vascular in-growth, as well as the incorporation of stem and/or other osteoprogenitor cells and growth factors. This includes platelet concentrates (PCs), bone morphogenetic proteins (BMPs), and some pharmacological agents, such as dipyridamole (DIPY), an adenosine A 2A receptor indirect agonist that enhances osteogenic and osteoinductive capacity, thus improving bone formation. This two-part review commences by presenting current biological and engineering principles of bone regeneration utilized to produce 3D-printed ceramic scaffolds with the goal to create a viable alternative to autografts for craniofacial skeleton reconstruction. Part II comprehensively examines recent preclinical data to elucidate the potential clinical translation of such 3D-printed ceramic scaffolds.

Indirect restorative systems-A narrative review.

OBJECTIVE: The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes. OVERVIEW: Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth. CONCLUSIONS: Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process. CLINICAL SIGNIFICANCE: The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.

In vitro assessment of the effect of luting agents, abutment height, and fatigue on the retention of zirconia crowns luted to titanium base implant abutments.

STATEMENT OF PROBLEM: The bonding of implant-supported prostheses is determined by abutment material, convergence angle, height, surface treatment, and luting agents. However, studies evaluating the bonding of luting agents to titanium base abutments with different heights under fatigue conditions are scarce. PURPOSE: The purpose of this in vitro study was to evaluate the retention of zirconia crowns bonded with different luting agents to titanium base abutments of different heights before and after fatigue testing. MATERIAL AND METHODS: Zirconia crowns were designed, milled, and distributed into 4 experimental groups according to the luting agents (G-Multi Primer/G-Cem LinkForce [MP/GC] and Scotchbond Universal/RelyX Ultimate [SU/RU]) and titanium base abutment heights (2.5 mm and 4 mm) (n=10). Pull-out testing was performed in a universal testing machine at a crosshead speed of 1 mm/min until crown displacement. Fatigue testing was performed by an electric precision fatigue simulator (1×106 cycles; 100 N; and 15 Hz), followed by pull-out testing of fatigued specimens. Collected data were statistically evaluated by using a linear mixed model after post hoc comparisons by the least significant difference test (α=.05). RESULTS: Luting agents, abutment heights, and fatigue influenced the bonding retention of zirconia crowns to titanium base abutments. SU/RU agents promoted higher pull-out compared with MP/GC for both abutment heights before and after fatigue. Higher abutment height increased pull-out regarding lower abutment height for SU/RU materials before and after fatigue testing. Although fatigue had no significant effect on the pull-out of MP/GC, lower bond retention was observed for SU/RU after fatigue, regardless of abutment height. CONCLUSIONS: Luting agent composition and the interaction with abutment height and fatigue influenced the retention of zirconia crowns to titanium base abutments.

Success Rate of Mandible Implants Placed in Vascularized Fibula Bone Graft: A Systematic Review.

This systematic review addressed the implant success rate after mandible reconstruction with vascularized fibula bone graft. Therefore, preferred reporting items for systematic review and meta-analysis guidelines were used to perform the systematic review, and the search included following databases: PubMed, Lilacs, Google Scholar, Open Gray, Science Direct and Cochrane. A search of medical subject headings (MeSH) and related terms (fibula) OR (vascularized) OR (microvascularized) AND (implant) OR (rehabilitation) OR (osseointegrated) AND (mandible) OR (jaw) OR (maxillofacial), without any language or time restrictions until October 2017 was carried out. The eligible studies primarily consisted of clinical cohorts designed to evaluate the feasibility of mandible reconstruction using vascularized fibula bone grafts and implant-supported rehabilitations, with a minimum observation period of 12 months. After screening, 13 eligible cohort studies for this review were selected (3 retrospective and 10 prospective). Of 285 vascularized fibular reconstructions, only 6 failures were reported with a success rate of approximately 98% after a mean follow-up period of 40 months. In total, 910 implants were placed in vascularized fibular grafts with a success rate of 92.6% (range, 82%-100%) after 40 months. Also, similar success rates for primary (95%; range, 93%-100%) and secondary (91%; range, 83%-100%) implant surgeries have been demonstrated. Considering risk factors, implant survival in irradiated patients was usually lower (76%; range, 38%-88%) than nonirradiated patients (90%; range, 83%-94%); however, it was significantly different in only 1 study. Alcohol and tobacco use has shown no significant association with implant failure in any study. Hence, implant placement in vascularized fibula bone graft presented similar success rates relative to native mandible bone rehabilitations.

Severely Atrophic Mandibles Restored With Fiber-Reinforced Composite Prostheses Supported by 5.0-mm Ultra-Short Implants Present High Survival Rates Up To Eight Years.

PURPOSE: Encouraging results have been reported for ultrashort single implants; however, long-term investigations are warranted for full-arch reconstructions. This study evaluated marginal bone loss, implant, and reconstruction survival of fiber-reinforced composite full-arch prostheses supported by 4 ultrashort implants. METHODS: Patients with severely atrophic mandibles (Cawood and Howell class V and class VI) were included in this cohort study. Study predictors included time (initial and last follow-up) and vertical (epicrestally or subcrestally) and horizontal implant position (medial or lateral). Outcome variables included bone level changes over time, implant/prosthesis survival. Peri-implant bone level was measured on panoramic radiographs. Descriptive statistics, Kaplan-Meier, mixed model analysis of variance, and univariate and multivariate Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used for data analyses. RESULTS: Eighteen patients (mean 61.22 years old), with 72 implants placed in atrophic mandibles with an average follow-up of 55.4 months (CI, ±4.6/ SD, ±10.6 months) were analyzed. The implant survival rate was 97.2% as 2 implants were not loaded due to non-osseointegration and sensorial disturbances. Average marginal bone level at baseline (1.93 mm) and at the time of last recall (1.91 mm) was not significantly different. While implants placed subcrestally showed no significant difference between baseline (1.91 mm) and last follow up bone level (2.12 mm), implants placed epicrestally demonstrated a significant reduction on their bone level over time (initial: 1.97 mm/ final:1.33 mm). Systemic disorders were a risk factor for implant survival and bone loss. Prostheses cumulative survival rate was 100% (mean observation period of 55 months). The estimated survival rate after the 96-month follow-up was 75% (1 framework fracture after 84 months). CONCLUSION: Fixed fiber-reinforced composite full-arch prostheses retained by 4 ultrashort implants showed a stable bone level and high implant/prostheses survival rates up to 8 years.

Antiresorptive therapy and dental implant survival: an up to 20-year retrospective cohort study in women.

OBJECTIVES: To investigate the effects of antiresorptive treatment on the survival of plateau-root form dental implants. MATERIALS AND METHODS: Patients undergoing antiresorptive therapy via oral or intravenous administration as well as patients not undergoing antiresorptive therapy and healthy control patients were included in this retrospective cohort study. In total, 1472 implants placed in 631 postmenopausal patients (M: 66.42 ± 9.10 years old), who were followed for a period of up to 20 years (8.78 ± 5.68 years). Kaplan-Meier survival analysis was performed, and univariate and multivariate Cox regression, clustered by each patient, was used to evaluate and study factors affecting the survival of their implants. RESULTS: Implants placed in patients undergoing oral antiresorptive treatment presented significantly higher survival rates, than implants placed in the osteoporosis/osteopenia control cohort (p value < 0.001), and similar survival rates, when compared to healthy controls (p value = 0.03). Additionally, clustered univariate and multivariate Cox regression analysis also revealed higher implant survival when oral antiresorptive drugs (p value = 0.01 and 0.007, respectively) were used, and lower implant survival in the presence of untreated osteoporosis/osteopenia (p value = 0.002 and 0.005, respectively). Overall, the 20-year implant survival in osteoporotic patients undergoing antiresorptive therapy was 94%. For the failed implants, newly replaced implants in patients under antiresorptive treatment presented a 10-year survival of 89%. CONCLUSIONS: Long-term plateau-root form implant survival in osteoporotic patients taking oral antiresorptives was similar to a healthy population and significantly higher than the untreated controls. CLINICAL RELEVANCE: These results suggest that plateau-root form implants provide a robust solution for treating tooth loss in patients, who are undergoing antiresorptive therapy.

Rehabilitation of Atrophic Maxilla With Immediate Loading of Extrasinus Zygomatic Implant.

ABSTRACT: The aim of this case series was to evaluate the long-term success rate of immediate occlusal loading of extrasinus zygomatic dental implants after a 3-year follow-up. The sample consisted of 31 patients (mean age of 64 years) with atrophic maxillae rehabilitated with 1 to 4 extrasinus zygomatic implants, placed unilaterally or bilaterally. All the patients received complete implant-supported dental prostheses with immediate loading by associating zygomatic implants with conventional implants. None of the procedures were associated with bone grafts. During the 3-year period of follow-up in the present study, all the patients attended clinical sessions and underwent radiographic exams every 6 months. In total 55 zygomatic and 69 conventional implants were placed, where 1 zygomatic and 2 conventional implants were lost, representing success rates of 98.18% and 97.20%, respectively. None of the studied patients had signs of sinusitis or changes in the maxillary sinuses. All the patients showed occlusal contact on natural antagonist teeth or implant-supported dental prostheses. Therefore, it was concluded that the use of exteriorized zygomatic implants with immediate loading represented a feasible option with high success rates for the treatment of atrophic maxilla.

Mechanical testing of four-unit implant-supported prostheses with extensive pink gingiva porcelain: The dentogingival prostheses proof of concept.

OBJECTIVE: To investigate the probability of survival and failure modes of four-unit implant-supported porcelain fused to metal (PFM) dentogingival prostheses subjected to step-stress accelerated life testing (SSALT). MATERIALS AND METHODS: Eighteen implant-supported PFM dentogingival prostheses with thin metallic infrastructures, which provided minimal ceramic support and improved esthetics were fabricated over external hexagonal connection UCLA abutments. SSALT was performed until specimen failure. Use level probability Weibull curve and reliability were calculated and plotted. Weibull modulus (m) and characteristic strength (η) were also calculated. Polarized light microscope and scanning electron microscope were used to characterize fractures. RESULTS: Failures were dictated by material strength rather than fatigue damage accumulation. The probability of survival for loads reaching 100 and 150 N in 100,000 cycles was 92 and 61%, respectively. No cracks or fractures were identified in the veneered porcelain, whereas abutment fixation screw fracture was the chief failure mode. CONCLUSION: Implant-supported PFM four-unit dentogingival prostheses with minimum metal framework dimensions presented favorable lifetime prediction under fatigue testing. Fractures were restricted to fixation screws. CLINICAL SIGNIFICANCE: In-vitro fatigue testing and failure mode analyses evidenced favorable lifetime prediction for 4-unit implant-supported dentogingival prostheses with minimum metal frameworks. Abutment fixation screw fracture might be the most frequent clinical complication. Since this proof of concept has been tested in-vitro, further studies including different restorative materials, as well as long-term clinical trials are warranted.

Ridge Architecture Preservation Following Minimally Traumatic Exodontia Techniques and Guided Tissue Regeneration.

OBJECTIVE: To compare hard-tissue healing after 3 exodontia approaches. MATERIALS AND METHODS: Premolars of dogs were extracted: (1) flapless, (2) flap, and (3) flap + socket coverage with polytetrafluoroethylene (dPTFE) nonresorbable membrane (flap + dPTFE). Animals were euthanized at 1 and 4 weeks. Amount of bone formation within socket and socket total area were measured. RESULTS: Amount of bone formation revealed significant difference between 1 and 4 weeks; however, there was no differences among groups. Socket total area decreased after 4 weeks, and the flap + dPTFE group showed significantly higher socket total area. As a function of time and group, flap + dPTFE 4 weeks presented similar socket total area values relative to flap + dPTFE at 1 week, and significantly higher socket total area than flapless and flap. The histological sections revealed almost no bone formation within socket after 1 week, which increased for all groups at 4 weeks. CONCLUSION: Socket coverage with polytetrafluoroethylene (dPTFE) membrane showed to effectively preserve bone architecture. Bone formation within sockets was not influenced by tooth extraction technique.

The Effect of CAD/CAM Crown Material and Cement Type on Retention to Implant Abutments.

PURPOSE: To evaluate the pullout resistance of CAD/CAM implant-supported crowns cemented with provisional and definitive cements on Ti-base implant abutments. MATERIALS AND METHODS: Sixty crowns were milled for use in Ti-base implant abutments and divided (n = 15/group) according to material, as follows: (a) [Pr] Temporary acrylic resin; (b) [Co-Cr] Cobalt-Chromium alloy; (c) [Zr] polycrystalline zirconia; and (d) [Ti] titanium. The cementation was performed with RelyX Temp NE (RxT) cement or RelyX U200 self-etching resin cement, under a 50 N (5 kg) load for 10 minutes. Twenty-four hours after cementation, the crowns were subjected to the pullout test in a universal test machine, at a 1.0 mm/min crosshead speed. The tests were performed first without cement to evaluate frictional resistance (Baseline), then with provisional cement (RelyX Temp NE without cement again (Baseline After RxT), and finally with resin cement (U200). The results were analyzed by ANOVA and Tukey test (p < 0.05). RESULTS: Data evaluation as a function of cement type demonstrated the superiority of resin-based cements relative to provisional and baseline groups (p < 0.01). While Co-Cr crowns presented the highest pullout strength values, Pr showed the lowest values (data collapsed over cement) (p < 0.001). Retentiveness data as a function of both factors demonstrated similar pullout resistance between groups without cement (p < 0.001), except Zr baseline. Also, Co-Cr presented higher pullout strength compared to other materials. CONCLUSIONS: Self-adhesive resin cement exhibited superior retention compared to temporary cement, regardless of crown material. Co-Cr and titanium presented higher levels of retention to Ti-base abutment after being cemented.

Effect of CAD/CAM Abutment Height and Cement Type on the Retention of Zirconia Crowns.

PURPOSE: To evaluate Ti-Base abutment height and cement type on the retentiveness of zirconia-based restorations. MATERIAL AND METHODS: Four millimeter (tall) and 2.5-mm-height (short) abutments along with temporary (provisional), glass ionomer (Meron), self-adhesive (U200), and conventional resin cement (Ultimate) were evaluated using pull-out testing (n = 10 crowns/group). RESULTS: Tall and short abutments demonstrated similar retention for all within cement comparisons, except U200 (P = 0.032). Resin cements exhibited superior retentiveness than others (P < 0.01). Although no significant difference was evidenced between resin cements for short abutments, Ultimate evidenced higher retention than U200 for tall abutments (P = 0.043). CONCLUSIONS: Although Ti-Base abutment height has not influenced zirconia superstructures' retentiveness, resin-based cements significantly evidenced higher retention than glass ionomer and temporary cements.

Partial fixed dental prostheses fabricated using fiber-reinforced composite resin supported by short and extra-short implants: A case series.

PURPOSE: This study aimed to evaluate the 10-year outcomes of partial fixed dental prostheses (P-FDPs) fabricated using metal-free fiber-reinforced composite (FRC) resin frameworks veneered with composite resin and supported by short and extra-short implants. METHODS: This study included 28 patients with 38 FRC prostheses supported by 96 implants. Implant and prosthesis survival and success rates were evaluated using Kaplan-Meier analysis. RESULTS: The 10-year implant survival and success rate, as determined by Kaplan-Meier analysis, was 96.9%, and the prosthesis survival and success rates were 94.7% and 92.0%, respectively. None of the parameters under investigation were significantly correlated with prosthetic survival or successful outcomes, but three parameters were correlated with higher peri-implant bone levels: implant placement in the mandible as opposed to the maxilla, shorter P-FDP spans, and natural teeth on the opposing arch. CONCLUSIONS: FRC P-FDPs supported by short and extra-short implants presented high, up to 10-year, survival and success rates, when used to restore partially edentulous arches.

Minimally processed recycled yttria-stabilized tetragonal zirconia for dental applications: Effect of sintering temperature on glass infiltration.

This study aimed to develop a recycling process for the remnants of milled 3Y-TZP and enhance their properties using glass infiltration. 3Y-TZP powder was gathered from the vacuum system of CAD-CAM milling equipment, calcined and sieved (x < 75 µm). One hundred twenty discs were fabricated and pre-sintered at 1000 °C/h. These specimens were then divided into four groups, categorized by glass infiltration (non-infiltrated [Zr] or glass-infiltrated [Zr-G]) and sintering temperature (1450 °C [Zr-1450] or 1550 °C [Zr-1550]/2h). After sintering, the specimens were characterized by X-Ray Diffraction (XRD), relative density measurement, and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). The biaxial flexural strength test was performed according to the ISO 6872 and followed by fractographic analysis. Subsequent results were analyzed using Weibull statistics. Relative density values of the sintered specimens from Zr-1450 and Zr-1550 groups were 86.7 ± 1.5% and 92.2 ± 1.7%, respectively. Particle size distribution revealed particles within the range of 0.1-100 µm. XRD analysis highlighted the presence of the ZrO2-tetragonal in both the Zr-1450 and Zr-1550 groups. Glass infiltration, however, led to the formation of the ZrO2-monoclinic of 9.84% (Zr-1450-G) and 18.34% (Zr-1550-G). SEM micrographs demonstrated similar microstructural characteristics for Zr-1450 and Zr-1550, whereas the glass-infiltrated groups exhibited comparable infiltration patterns. The highest characteristic strength was observed in the glass-infiltrated groups. Fractographic analyses suggested that fracture origins were related to defects on the tensile side, which propagated to the compression side of the samples. Both the sintering temperature and glass infiltration significantly influenced the mechanical properties of the 3Y-TZP recycled.

Sustained Release of Salicylic Acid for Halting Peri-Implantitis Progression in Healthy and Hyperglycemic Systemic Conditions: A Gottingen Minipig Model.

To develop a peri-implantitis model in a Gottingen minipig and evaluate the effect of local application of salicylic acid poly(anhydride-ester) (SAPAE) on peri-implantitis progression in healthy, metabolic syndrome (MS), and type-2 diabetes mellitus (T2DM) subjects. Eighteen animals were allocated to three groups: (i) control, (ii) MS (diet for obesity induction), and (iii) T2DM (diet plus streptozotocin for T2DM induction). Maxillary and mandible premolars and first molar were extracted. After 3 months of healing, four implants per side were placed in both jaws of each animal. After 2 months, peri-implantitis was induced by plaque formation using silk ligatures. SAPAE polymer was mixed with mineral oil (3.75 mg/µL) and topically applied biweekly for up to 60 days to halt peri-implantitis progression. Periodontal probing was used to assess pocket depth over time, followed by histomorphologic analysis of harvested samples. The adopted protocol resulted in the onset of peri-implantitis, with healthy minipigs taking twice as long to reach the same level of probing depth relative to MS and T2DM subjects (∼3.0 mm), irrespective of jaw. In a qualitative analysis, SAPAE therapy revealed decreased levels of inflammation in the normoglycemic, MS, and T2DM groups. SAPAE application around implants significantly reduced the progression of peri-implantitis after ∼15 days of therapy, with ∼30% lower probing depth for all systemic conditions and similar rates of probing depth increase per week between the control and SAPAE groups. MS and T2DM conditions presented a faster progression of the peri-implant pocket depth. SAPAE treatment reduced peri-implantitis progression in healthy, MS, and T2DM groups.