Zirconia Prostheses Research Articles

Prosthetic complications with monolithic or micro-veneered implant-supported zirconia single-unit, multiple-unit, and complete-arch prostheses on titanium base abutments: A single center retrospective study with mean follow-up period of 72.35 months.

The influence of prosthetic design on prosthetic complications when monolithic or micro-veneered zirconia prostheses are supported with titanium base (ti-base) abutments is not well-known. The purpose of this single center, retrospective study was to assess the prevalence of prosthetic complications with monolithic or micro-veneered single-unit, multi-unit, and complete-arch zirconia prostheses supported with ti-base abutments (implant level or multi-unit abutment level). This study retrospectively evaluated the electronic health record (EHR) of participants who received either monolithic or micro-veneered implant-supported single-unit, multi-unit, and/or complete-arch prostheses supported by ti-base or zirconia-ti-base hybrid abutments delivered between the years 2010 and 2021. Data were analyzed by using logistic regression and Exact Mantel-Haenszel chi-square test (α=0.05) to assess the clinical performance of prostheses and complications including crown decementation, feldspathic porcelain chipping, prosthesis fracture, zirconia-ti-base hybrid abutment decementation, abutment screw loosening, screw fracture, abutment fracture, implant loss, and prosthesis remake. The study included 94 participants (50 female, 44 male) with a mean age of 59.5 years (range: 24-101 years of age). The retrospective EHR evaluation yielded 82 single-unit, 51 multi-unit, and 20 complete-arch prostheses on 325 implants. Among 153 prostheses delivered, 108 were micro-veneered (47 single-unit, 41 multi-unit, and 20 complete-arch prostheses) and 45 were monolithic. The average duration was 72.35 months (6.02 years) with a follow-up period of 5-132 months. From the time of insertion to the time of EHR review, of 153 prostheses, 78.43% did not exhibit any prosthetic complication. However, 33 prostheses (21.57%) from 29 participants (30.85%) had at least one prosthetic complication. Only four patients (4.25%) experienced two or more prosthetic complications. Prosthetic design affected the probability of having a complication (p=0.005); complete-arch prostheses had higher probability (p ≤ 0.028). Single-unit prostheses had lower probability of complication than multi-unit prostheses (p=0.005). The most commonly observed complication was fracture of veneering material (5.88%) followed by prosthetic screw loosening (4.57%) and decementation between the zirconia and the ti-base abutment (2.61%). Micro-veneered complete-arch prostheses had higher probability of having chipping than that of not having (p < 0.001), and other micro-veneered prosthetic designs had similar probability of chipping with that of complete-arch prostheses (p ≥ 0.082). Frequency of chipping was affected by veneering (p < 0.001). Monolithic prostheses had lower probability of chipping than micro-veneered prostheses, regardless of the prosthetic design (p < 0.001). The frequency of prosthetic complications varied depending on prosthetic design. Complete-arch prostheses had the highest probability of complications while the single-unit prostheses had the lowest. Micro-veneered prostheses had higher probability for chipping than monolithic prostheses. Probability of chipping was similar for micro-veneered single-unit, multi-unit, and complete-arch zirconia prostheses.

Effect of 9% Hydrofluoric Acid Gel Hot-Etching Surface Treatment on Shear Bond Strength of Resin Cements to Zirconia Ceramics.

Background and Objectives: There is no consensus regarding the surface treatment method for achieving optimal bonding strength between zirconia and resin cements. We evaluated the effect of hot-etching with 9% hydrofluoric acid (HF) gel using the Zirconia Etchant Cloud System on zirconia surfaces and the consequent shear bond strength (SBS) of different resin cements to such surface-treated zirconia ceramics. Materials and Methods: Forty-five zirconia specimens were randomly assigned to surface-treatment groups (n = 15/group): no treatment (control, CT); sandblasting with 110-μm Al2O3 at an air pressure of 1 bar for 10 s (SB); hot-etching with 9% HF gel (HE). Post-treatment, specimens were examined using scanning electron microscopy (SEM) and surface roughness (SR) analysis. After treatment, self-adhesive resin cements (Maxcem Elite, MAZIC Cem, RelyX U200, 3M ESPE: Maplewood, MN, USA) were bonded to zirconia specimens, which were stored in distilled water at 37 °C for 24 h. All specimens were then subjected to SBS testing, using a universal testing machine, until failure. Data were analyzed using one-way analysis of variance and Tukey’s post hoc test (α = 0.05). Results: In the SEM images, roughness was greater in SB than in HE specimens. Ra and Rt values were highest in SB, followed by HE, and CT specimens. HE specimens showed significantly higher SBS values than CT or SB specimens (p < 0.05). MAZIC Cem cement, with 10-methacryloyloxydcyl dihydrogen phosphate yielded the highest SBS values. Conclusions: Hot-etching with 9% HF gel in a safe shell formed uniformly small, defined holes on the zirconia surface and achieved significantly higher SBS values than sandblasting (p < 0.05). Zirconia prostheses can be bonded micromechanically with resin cement, without the deterioration of properties due to t-m transformation, using chemical acid etching with the Zirconia Etchant Cloud System.

Effect of milling and sintering process on integrity of zirconia prosthesis: a literature review

Effect of milling and sintering process on integrity of zirconia prosthesis: a literature review

Effect of Different Sintering Cycles on the Flexural Strength of Full Contour Monolithic Zirconia – An In-Vitro Comparative Study

BACKGROUND&#x0D; Monolithic zirconia restorations are known to exhibit good mechanical properties and acceptable aesthetics. During the fabrication of zirconia prostheses, the sintering process is the most critical step which determines the performance of the final product. However, a lot of issues with zirconia restorations were related to sintering cycles which can affect the crystalline content and grain growth that can affect its mechanical properties. The purpose of this study was to evaluate and compare the effect of different sintering cycles on the flexural strength of full-contour monolithic zirconia.&#x0D; METHODS&#x0D; In this in-vitro study, a total of 44 bar-shaped zirconia samples (Amann Girrbach Ceramill® CAD/CAM Material – ZOLID HT+) of final dimensions 20 x 4 x 2 mm were fabricated using Amann Girrbach Ceramill mind – computer-aided designing software and Amann Girrbach Ceramill® motion2 – computer-aided milling unit. These samples were randomly allocated into four groups with 11 samples in each group namely, Group 1, 2, 3 and 4 (Group 1: Long sintering cycle, Group 2: Intermediate sintering cycle, Group 3: Short sintering cycle, Group 4: Ultra-short sintering cycle) and sintered under the respective sintering cycles. The Ceramill® therm (Amann Girrbach) sintering furnace provided 3 sintering cycles ranging from the longest group-1 (19 hours), to the short sintering cycle group-3 (8 hours), with an intermediate sintering cycle group-2 (15 hours). The zircon (KDS) sintering furnace provided an ultra-short sintering cycle group-4 (2 hours). The testing of flexural strength was performed using a three-point bend test on a universal testing machine. Statistical analysis of the collected data was performed by one-way ANOVA using SPSS software.&#x0D; RESULTS&#x0D; One-way ANOVA showed no statistically significant difference in the flexural strength of full-contour monolithic zirconia sintered under the four different sintering cycles. (P &gt; 0.05).&#x0D; CONCLUSIONS&#x0D; The flexural strength of full-contour monolithic zirconia was influenced to some extent by various sintering cycles. The longest sintering cycle (Group 1) showed the least flexural strength whereas the intermediate sintering cycle (Group 2) showed the highest flexural strength. Also, the ultra-short sintering cycle (Group 4) of 2 hours exhibited flexural strength comparable to the rest of the groups with longer sintering cycles, thus making the cycle a viable alternative to the conventional sintering cycles, thereby making the ‘tooth-in-a-day‘ possible for the patients.

Effect of high-speed sintering modes of Russian zirconia samples made of Ziceram T on strength indicators and color

BACKGROUND: In recent years, zirconia prostheses have gradually become a mass type of orthopedic treatment. The production of zirconium dioxide blanks for dentistry has also been launched in our country. In recent years, the possibility of speed sintering of dental prostheses made of zirconia has been widely calculated, which makes it possible to reduce the process of manufacturing structures by four to five times.&#x0D; AIM: To investigate the effect of high-speed sintering on important properties, such as strength characteristics during three-point bending and color parameters at 10 different modes of speed sintering of ceramic materials.&#x0D; MATERIALS AND METHODS: The work uses samples obtained by computer-aided design and computer-aided manufacturing milling from domestic Ziceram T blanks, color A2. Depending on the firing modes, the samples were divided into 11 groups. The strength of the sintered samples was studied with three-point bending on a bursting machine. The color parameters of the samples were determined on the Spectron-M color analyzer in the CIE L*a*b system on a white and black background using acceptable norms of color difference and characteristics of color shades.&#x0D; RESULTS: According to the results of tests for resistance to bending, susceptibility has an approximate value of more than 300 MPa. According to ISO 6872, this flexural strength is sufficient for the fabrication чof single crowns in both anterior and posterior teeth. An increase in the lightness of ceramic samples based on zirconium dioxide from domestic factories Ziceram T of Zircon Ceramics was established. The reduced firing time led to an increase in body weight, which is associated with a decrease in their intensity.&#x0D; CONCLUSION: Express firing modes of ceramics based on zirconium dioxide Ziceram T guarantee the achievement of the required strength. However, none of the studied firing modes allowed achieving the color parameters of the control samples.

Evaluation of Immediately Loaded Parallel Conical Connection Implants with Platform Switch in the Maxillary Esthetic Zone: A Prospective Clinical Study

To assess immediately loaded parallel conical connection (Nobel Biocare) implants with platform switch design in the maxillary esthetic zone for soft and hard tissue changes. A total of 20 patients (n = 20) underwent prosthetic replacement of the missing maxillary anterior tooth, with an immediately loaded parallel conical connection implant (Noble Biocare, Sweden) having a platform switch design. The size of the implant was 3.75 mm in width and 13 mm in length for all patients and placement followed a standardized surgical protocol. Postoperatively, acrylic provisionalization was done within 48 hours followed by a definitive zirconia prosthesis in the 3rd month. Clinically and radiographically, the implants were evaluated for hard tissue (bone density, implant stability, crestal bone loss) and soft tissue changes (mucosal thickness-MT, sulcus probing depth-PD, bleeding on probing-BOP, width of keratinized gingiva-KG) at baseline till 36 months with follow-up intervals after loading. All patients showed uneventful healing. The difference in implant stability and density scores was significant (p <0.05*) from baseline to 36 months indicating bone formation and osseointegration of the implant. Bleeding on probing was not observed, and probing depth remained within the acceptable range (≤5 mm) at all time intervals after loading. The marginal bone loss was minimal (≤0.2 mm annually) with the absence of implant mobility and without any peri-implant radiolucency. The thickness of the gingiva (3.47 ± 0.34 mm) and width of keratinized gingiva (2.46 ± 0.39 mm) remained within reasonable limits at the 36th month with acceptable esthetic appearance. In the present study, immediate loading of Nobel parallel conical connection implant in the maxillary anterior region provided adequate primary stability, minimal marginal bone loss, and increased bone density indicating earlier osseointegration. Decreased probing depth, absence of bleeding on probing, and adequate tissue collar at the neck showed better soft tissue emergence in the esthetic zone. The platform switch design demonstrated promising results and therefore can be used as an alternative to the conventional method. The present study results suggest that parallel conical connection implants (Nobel Biocare) with TiUnite surface, built-in platform switch combined with conical connection interface, parallel walled body, tapered apex, and double threads from tip to platform are all designed to provide high primary stability and support immediate function protocol, hence can be used flexibly in different bone densities.

Application of Rapid Prototyping in Prosthodontics

Purpose: Rapid Prototyping (RP) methods have for quite some time been utilized to construct complex 3-Dimensional (3D) models in the field of medicine since the 1900s. This paper intends to offer a thorough audit of different RP strategies, especially in Prosthodontics that are relied upon to carry numerous enhancements to this field. Materials and Methods: A pursuit was made using the Google scholar web and the PubMed database as a search engine. The keywords; ‘RP’, ‘rapid prototyping’, ‘3D printing’, ‘dentistry’ and ‘prosthodontics’, ‘stereolithography’, ‘selective laser sintering’, ‘fused deposition method’, and ‘inkjet-based system’ were looked at in the title/abstract of distributions. References of selected articles were additionally looked into for conceivable incorporation in the study. The selected articles utilized RP procedures in different fields of dentistry through various methods. Nonetheless, distributions concerning the dental utilization of RP advancements are as yet uncommon. Results: Although the concept of layering 3D objects is almost as old as human civilization, this technology has only lately been applied to the construction of 3D complex models in dentistry. Many additional methods appear to be on the horizon that could alter standard dentistry practises in the near future. More unit hours should be included in dentistry curriculums to familiarise dental professionals with the various advantages of this unique technology. Conclusion: Lately, RP using the property of adding substances or layering strategies have advanced quickly in different fields of dentistry as they can overcome known disadvantages of subtractive and regular procedures. RP has as of late proposed effective uses in different fields of dentistry, like fabrication of implant surgical guides, structures for Removable Partial Dentures (RPDs), Fixed Partial Dentures (FPDs), wax designs for the dental prosthesis, maxillofacial prosthesis, zirconia prosthesis, and molds for metal castings now as well for complete dentures.

A Shift to Synergistic Surface Treatment Using Laser to Enhance the Bonding of Zirconia to Veneering Ceramic: An In Vitro Study

The aim of this study was to evaluate the effect of combination of surface treatment using laser along with other modalities of surface treatment on shear bond strength of zirconia to veneering ceramic. Milled and sintered zirconia cylinders (n = 150) were used in the study which were divided into six groups that were subjected to various surface treatments. Samples in group I were subjected to sandblasting. In group II Laser (Er: YAG) surface treatment was performed. Samples in group III were subjected to sandblasting followed by laser ablation. In group IV laser ablation was carried out followed by liner application, and samples in group V were subjected to laser ablation followed by argon plasma treatment. Instron machine was used to test the shear bond strength (SBS). One-way ANOVA and Bonferroni test were used for statistical analysis. Samples in group III showed highest values for SBS followed by groups I, IV, and V with less SBS value for group II. Thus, the results conclude the use of combination of surface treatment using laser to be an effective modality to enhance the shear bond strength of zirconia. Synergistic surface treatment using laser increases the bond strength of zirconia prosthesis to veneering ceramic improving its clinical longevity.

Complete Digital Workflow for Prosthesis Prototype Fabrication with Double Digital Scanning: Accuracy of Fit Assessment.

To assess the accuracy of a complete digital workflow protocol for fabrication of printed prosthesis prototypes for maxillary immediate loading treatment. A maxillary stone cast with 4 abutment-level implant analogs with adequate antero-posterior spread was fabricated. This stone cast served as a reference cast and a zirconia prosthesis was also fabricated to serve as an interim prosthesis. Double digital scanning was used for digital scans of the reference cast and the interim prosthesis, respectively. An intraoral scanner (TRIOS® 3) was used to capture the standard tessellation language (STL) files. These STL files were then imported to computer-aided design (CAD) software (Exocad DentalCAD) and superimposed into a final design STL file that was exported to 3 different (Form 3b+, Carbon M2, Sprintray Pro95) three-dimensional (3D) printers to produce a total of 90 printed prototypes (n = 30 from each 3D printer). Two blinded clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the reference cast, utilizing the screw-resistance test and radiographs. The Fisher's exact test was used to test the difference between the groups. Out of the 90 digitally fabricated prototypes, 86 (95.6%) presented with accurate fit. The accuracy of fit ranged from 87% (26/30) for Sprintray Pro95 to 100% (30/30) for the Form 3b+ and M2 Carbon groups. Digitally fabricated prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit, while reducing the number of appointments and treatment time. The 3D printer had an effect on the accuracy of prosthesis prototype fit.

Effects of Three Novel Bracket Luting Agents Containing Zirconia Primer on Shear Bond Strength of Metal Orthodontic Brackets Attached to Monolithic Zirconia Crowns: A Preliminary In Vitro Study.

Background The increased use of zirconia crowns in adult orthodontic patients warrants the establishment of methods and materials to adhere orthodontic brackets properly to zirconia crowns. However, studies in this regard are scarce, and many materials remain untested. This preliminary study aimed to examine three new adhesives containing zirconia primers for the first time. Methods Sixty identical monolithic zirconia crowns were fabricated and randomly divided into 4 groups of 15 each (Panavia SA Cement Plus, G-CEM, TheraCem, and Transbond XT Composite (control)). After glaze removal with a diamond bur, a metal orthodontic bracket was attached to the surfaces of the crowns using the respective adhesive. Specimens were incubated at 37°C and then thermocycled for 2000 cycles. Shear bond strengths (SBS) of brackets in different groups were estimated using a universal testing machine. Mean SBS values were compared with the values 6, 8, and 10 (as acceptable SBS values) and 13 MPa (as the maximum SBS tolerable by zirconia) using the one-sample t-test. They were also compared with each other using the one-way ANOVA and Tamhane post hoc test (α = 0.05). Results The ANOVA indicated a significant overall difference; the Tamhane test showed that the difference between the control group and all test groups was significant (P < 0.0005); however, the 3 test groups were not significantly different from each other (P > 0.30). The SBS of the control group was significantly lower than the minimum acceptable SBS (6 MPa, P < 0.0005). The mean SBS of the TheraCem was not significantly different from 10 MPa (P = 0.902), while the mean SBS values of Panavia SA Cement Plus and G-CEM were significantly greater than 10 MPa (P < 0.05). None of the three zirconia adhesives had mean SBS values higher than 13 MPa. Conclusion All novel zirconia adhesives (Panavia SA Cement Plus, G-CEM, and TheraCem) generated SBS values adequate to attach metal orthodontic brackets to zirconia prostheses (at or greater than 10 MPa) without damaging the zirconia during bracket removal (not above 13 MPa).

Improving wear resistance of acrylic resin denture teeth by using zirconia complete crowns fabricated with a CAD-CAM double-scanning method: A clinical report

Acrylic resin denture teeth can wear and chip when opposed by zirconia prostheses. This clinical report describes the use of zirconia complete crowns to prevent these problems. The predictability of treatment was improved by using the computer-aided design and computer-aided manufacturing (CAD-CAM) double-scanning method.

Biomechanical finite element analysis of short-implant-supported, 3-unit, fixed CAD/CAM prostheses in the posterior mandible

ObjectiveTo assess the biomechanical effects of different prosthetic/implant configurations and load directions on 3-unit fixed prostheses supported by short dental implants in the posterior mandible using validated 3-D finite element (FE) models.MethodsModels represented an atrophic mandible, missing the 2nd premolar, 1st and 2nd molars, and rehabilitated with either two short implants (implant length-IL = 8 mm and 4 mm) supporting a 3-unit dental bridge or three short implants (IL = 8 mm, 6 mm and 4 mm) supporting zirconia prosthesis in splinted or single crowns design. Load simulations were performed in ABAQUS (Dassault Systèmes, France) under axial and oblique (30°) force of 100 N to assess the global stiffness and forces within the implant prosthesis. Local stresses within implant/prosthesis system and strain energy density (SED) within surrounding bone were determined and compared between configurations.ResultsThe global stiffness was around 1.5 times higher in splinted configurations vs. single crowns, whereby off-axis loading lead to a decrease of 39%. Splinted prostheses exhibited a better stress distribution than single crowns. Local stresses were larger and distributed over a larger area under oblique loads compared to axial load direction. The forces on each implant in the 2-implant-splinted configurations increased by 25% compared to splinted crowns on 3 implants. Loading of un-splinted configurations resulted in increased local SED magnitude.ConclusionSplinting of adjacent short implants in posterior mandible by the prosthetic restoration has a profound effect on the magnitude and distribution of the local stress peaks in peri-implant regions. Replacing each missing tooth with an implant is recommended, whenever bone supply and costs permit.

The Effect of Commercially Available Desensitizers on Bond Strength Following Cementation of Zirconia Crowns Using Self-Adhesive Resin Cement-An In Vitro Study.

The improvement of the tensile strength of zirconia crowns after the application of commercially available desensitizers can provide added advantages for the durability and strength of zirconia prostheses. We assessed the retention of zirconia crowns when Gluma, Shield Force Plus, and Telio CS desensitizers were used with resin luting cement. Four groups with ten specimens each (n = 10) were considered as Group 1 (Control group, with no desensitizer application before crown cementation with resin cement) and Groups 2, 3, and 4 (with a single coat of Gluma dentin desensitizer, Telio CS desensitizer, or Shield Force Plus desensitizer applied before crown cementation, respectively). Thermocycling was then carried out, and each group was tested to determine the associated retentive forces and type of failure. The data were statistically analyzed, which showed that the mean tensile-strength values were significantly higher in Group 2 (p-value = 0.001), Group 3 (p-value = 0.027), and Group 4 (p-value = 0.014), when compared with the Control group. Clinicians should consider the application of any of these three desensitizers, as they can successfully abate dentin hypersensitivity after tooth preparation, as well as increase the durability and strength of the zirconia prosthesis.

Evaluation of intaglio surface trueness, wear, and fracture resistance of zirconia crown under simulated mastication: a comparative analysis between subtractive and additive manufacturing.

PURPOSEThis in-vitro analysis aimed to compare the intaglio trueness, the antagonist’s wear volume loss, and fracture load of various single-unit zirconia prostheses fabricated by different manufacturing techniques.MATERIALS AND METHODSZirconia crowns were prepared into four different groups (n = 14 per group) according to the manufacturing techniques and generations of the materials. The intaglio surface trueness (root-mean-square estimates, RMS) of the crown was measured at the marginal, axial, occlusal, and inner surface areas. Half of the specimens were artificially aged in the chewing simulator with 120,000 cycles, and the antagonist’s volume loss after aging was calculated. The fracture load for each crown group was measured before and after hydrothermal aging. The intaglio trueness was evaluated with Welch’s ANOVA and the antagonist’s volume loss was assessed by the Kruskal-Wallis tests. The effects of manufacturing and aging on the fracture resistance of the tested zirconia crowns were determined by two-way ANOVA.RESULTSThe trueness analysis of the crown intaglio surfaces showed surface deviation (RMS) within 50 µm, regardless of the manufacturing methods (P = .053). After simulated mastication, no significant differences in the volume loss of the antagonists were observed among the zirconia groups (P = .946). The manufacturing methods and simulated chewing had statistically significant effects on the fracture resistance (P < .001).CONCLUSIONThe intaglio surface trueness, fracture resistance, and antagonist’s wear volume of the additively manufactured 3Y-TZP crown were clinically acceptable, as compared with those of the 4Y- or 5Y-PSZ crowns produced by subtractive milling.

Titanium versus zirconia complete arch implant-supported fixed prostheses: A comparison of plaque accumulation

Statement of problemComplete arch implant-supported zirconia prostheses appear to have less plaque accumulation than titanium prostheses, but a comparison of the materials and the possible influence on the adjacent soft tissue is lacking. PurposeThe purpose of this clinical study was to compare the plaque accumulation and soft-tissue inflammation of complete arch implant-supported fixed maxillary prostheses fabricated with either a titanium framework or monolithic zirconia. Material and methodsTwenty participants with a complete arch implant-supported fixed maxillary prosthesis were enrolled in the study. The participants were divided into 2 groups according to the prosthesis material, titanium (Ti) or zirconia (Zir). The prosthesis had to have been in function for at least 6 months, and participants were examined during at least 3 maintenance appointments at 3-month intervals. Clinical information collected in each appointment included standardized photographs to record the Plaque Area Index (PAI) of the intaglio surface of the prosthesis; clinical parameters including modified Plaque Index (mPI), modified Bleeding Index (mBI), implant mobility (MOB), probing depths ≥5 mm (PD), suppuration (SUP), keratinized tissue band ≥2 mm (KT), and an intraoral photograph of the maxillary arch without the prosthesis to evaluate the redness of the soft tissues. ResultsMOB was not present at any implant at any time point. SUP could not be analyzed because it was an infrequent finding. Both groups exhibited significant increases in mBI over time. No significant differences were observed for PD between the groups at any time point. Implants in the Ti group had significantly higher KT values than those in the Zir group; levels remained constant over time for both groups. Zirconia prostheses had slightly lower PAI levels than Ti prostheses. The PAI in the Zir group significantly decreased over time (P=.035); in the Ti group, they remained constant (P=.45). Higher PAI levels were correlated with increased levels of erythema; both groups had a significant decrease in erythema values over time (P=.04). ConclusionsZirconia complete arch implant-supported fixed maxillary prostheses displayed a significant decrease in plaque accumulation in individuals who had received periodic maintenance and oral hygiene instructions. Ti prostheses had significantly higher plaque levels than zirconia prostheses at all time points, which was not reduced by maintenance and oral hygiene measures. The present study suggests that patients receiving zirconia prostheses respond well to plaque control measures, while plaque control for those with titanium prostheses may be more challenging.

Effect of Cooling Rate during Glazing on the Mechanical and Optical Properties of Monolithic Zirconia with 3 mol% Yttria Content.

Glazing is the final heat treatment process in the manufacturing of a monolithic zirconia prosthesis. Herein, the effect of cooling rate during zirconia glazing was investigated. A 3 mol% yttria-stabilized tetragonal zirconia polycrystal was glazed at the general cooling rate suggested by the manufacturer, as well as at higher and lower cooling rates, and the differences in flexural strength, hardness, optical properties, and crystal structure were evaluated. A higher cooling rate did not affect the flexural strength, hardness, grain size, optical properties, or crystal structure; however, the Weibull modulus decreased by 1.3. A lower cooling rate did not affect the flexural strength, optical properties, or crystal structure; however, the Weibull characteristic strength increased by 26.7 MPa and the Weibull modulus increased by 0.9. The decrease in hardness and the increase in grain size were statistically significant; however, the numerical differences were negligible. This study revealed that a lower cooling rate provides more reliable flexural strength. Therefore, glazing can proceed at a general cooling rate, which takes 3–4 min; however, glazing at a lower cooling rate will provide a more consistent flexural strength if desired, despite being time-consuming.

Digital Workflow for Double Complete Arch Zirconia Prostheses Utilizing a Novel Scan Body.

The purpose of this clinical report is to present a complete digital workflow for the fabrication of complete arch fixed zirconia implant restorations. An intraoral scanner was used to capture the implants' position at the abutment level and also the patient's existing interim prostheses with the double digital scanning technique. A novel scan body and impression pin were utilized throughout the scanning process which allowed for the accurate and reproducible superimposition of the generated Standard Tesselation Language (STL) files. Prosthesis prototypes were digitally designed and fabricated, tried in, and verified intraorally. The definitive zirconia prostheses were then fabricated and delivered to the patient. This technique can be utilized in both arches overcoming the absence of stable intraoral landmarks for superimposition of STL files.

Survival Rates of Anterior-Region Resin-Bonded Fixed Dental Prostheses: An Integrative Review.

This study aimed to review clinical publications involving anterior-region resin-bonded fixed partial dentures to evaluate their survival rates vis-à-vis their materials and design. An electronic search was conducted using PubMed/MEDLINE to identify articles that reported on the longevity of anterior resin-bonded fixed dental prostheses published between 2000 and 2020. Only primary clinical studies that involved a follow-up after at least 3 years were included in this review. A statistical analysis was performed to evaluate resin-bonded fixed dental prostheses’ survival rates in relation to their materials and design. This review ultimately included 23 clinical publications, comprising prospective studies, retrospective studies, and randomized controlled trials. Its statistical analysis estimated the studied prostheses’ 5-year survival rate at 86.2% for metal-framed prostheses, 87.9% for zirconia prostheses, 93.3% for alumina prostheses, 100% for glass or ceramic prostheses, and 81.7% for fiber-reinforced composite restorations. Failure rates did not significantly differ between the different material groups or between the single- and double-retainer groups. Resin-bonded fixed dental prostheses present excellent 5-year clinical longevity in the anterior sector and a favorable benefit/risk/cost ratio. Currently, no consensus has been established on an ideal material for these restorations. Cantilever design tends to limit constraints on the prostheses’ retainers and, thus, increases their survival time. All-ceramic cantilever fixed partial dentures can be considered as a definitive therapy, given their high success and survival rates. They are an optimal solution for adolescents or young adults facing potentially continuous growth.

Digitally Designed and Milled Verification Jigs Generated from Photogrammetry Data Acquisition: A Clinical Report.

The objective of the present report is to illustrate a proof-of-concept protocol for CAD/CAM fabrication of milled verification jigs during full-arch implant rehabilitation using photogrammetry for data acquisition. The present report aims to bridge the gap between analog and digital workflows by introducing a CAD/CAM technique to intraorally verify digitally acquired information without the use of the technique-sensitive and labor-intensive conventional resin verification jig. One patient was treated with a digital prosthodontic protocol where a digitally designed CAD/CAM milled verification jig (generated from intraoral digital scans) was used to confirm implant 3D positioning prior to the fabrication of double full-arch monolithic definitive zirconia prostheses. The procedures are presented step-by-step after clinical and radiographic observation.

Long-term survival and success of zirconia screw-retained implant-supported prostheses for up to 12 years: A retrospective multicenter study

Statement of problemDespite the broad clinical application of zirconia for fixed implant-supported prostheses, evidence of long-term performance is sparse. PurposeThe purpose of this retrospective study was to evaluate the long-term clinical and radiographic outcomes of zirconia-based partial and complete screw-retained implant-supported zirconia fixed dental prostheses (ISZFDPs). Material and methodsRecords of patients treated with dental implants and ISZFDPs between December 2004 and June 2017 were screened. Eligible study participants, according to inclusion criteria, were contacted and invited to undergo clinical and radiographic examinations. Outcomes were evaluated as implant and prosthetic survival rates, prosthetic success rate, complications, marginal bone level (MBL) change, and soft tissue condition. Along with the effects of zirconia prosthesis type and level, the effects of implant type and connection, type of loading, and follow-up on MBL were tested with a generalized linear effects model (GLEM) (α=.05). ResultsA total of 118 patients were identified, of whom 20 (16.9%) were not available for clinical examination for various reasons. Ninety-eight participants (mean age 60.7 ±11.7 years) with 337 implants were included, of which 176 (52.2%) had been immediately loaded. A total of 111 ISZFDPs (96 zirconia connection and 15 titanium base) were investigated: 24 complete ISZFDPs with a zirconia connection (12.9 ±0.97 dental units, minimum 12, maximum 14), 72 partial with a zirconia connection (3.11 ±1.12, minimum 2, maximum 7), 15 partial with a titanium base (3.62 ±1.02, minimum 2, maximum 5). Forty ISZFDPs had been in function for ≥10 years (36%), 38 for 5 to 9 years (34.2%), and 33 for 2 to 4 years (22.8%). The mean follow-up time was 7.2 ±3.4 years. No zirconia fractures were identified. Two implants and 2 ISZFDPs failed, with chipping being the most common complication (13.5%). The implant survival rate was 99.4%, and the prosthetic survival rate was 98.2%. The cumulative prosthetic success rate was 91.9%. MBL change was -0.18 ±0.59 mm. Thirteen implants were treated for peri-implantitis (3.8%), and 9 for mucositis (2.7%), but presented healthy peri-implant soft tissues at the follow-up examination. A significant difference was found between the implant-level and abutment-level prostheses (P=.013), with less marginal bone loss observed in ISZFDPs delivered at the implant level. ConclusionsZirconia-based screw-retained implant-supported prosthesis can be considered a reliable long-term treatment option for partial and complete edentulism. No zirconia fractures were experienced. Stable bone levels and low peri-implantitis rates were reported regardless of the ISZFDP type and level, implant type and connection, and type of loading.