Ceramic Superstructures Research Articles

Influence of cement shade, ceramic thickness, and airborne-particle abrasion of titanium surface on the final color of monolithic lithium disilicate glass-ceramic hybrid-abutment systems in vitro.

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. 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). 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. 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.

Fatigue Loading Test on Screw-Retained Lithium Disilicate Crowns Adhesively Cemented on Titanium Abutment

The aim of this study was to assess the mechanical behavior and the microleakage of crown abutments made of lithium disilicate (LDS), adhesively bonded to preconditioned titanium bonding base under dynamic loading considering the type of teeth incisors, premolars, and molars. Thirty-three monolithic LDS implant supra-structures, representing a copy of natural tooth morphology (central incisor, second premolar, or first molar) were fabricated and bonded to titanium bases, screw-retained on the implant, and subjected to dynamic loading of 250,000 loading cycles at 2 Hz. After mechanical cycling, specimens were immersed in 5% methylene blue solution for 24 h at 37 °C. Microleakage was evaluated under magnification. The presence or absence of the following parameters were also evaluated: abutment screw deformation, abutment deformation, crack or craze line on the ceramic structure, adhesive failure between titanium base and ceramic superstructure, failures in ceramic superstructure or titanium base, and remaining cement around titanium base and ceramic superstructure. Considering the type of teeth, there are eight defects in relation to the group of central incisors, whereas the group of first molars accounts for seven defects. The second premolar is the worst performer with eleven defects. Significant accumulation of dye was registered in all teeth groups, i.e., grade 2 (staining around hexagonal area of the connection), according to the applied scale. Failure of hybrid abutments could be related to the correct seal between the titanium base and the ceramic restorations. The type of teeth could also be related to the presence of failures.

EVALUATION OF BIOMECHANICAL EFFECTS OF PROSTHETIC COMPONENTS WITH DIFFERENT MATERIALS ON THE ABUTMENT SCREW

Objectives: The purpose of this study was to evaluate the effects of different resin-based and ceramic superstructure materials and two different abutment types on the stress distribution of the abutment screw using the three-dimensional finite element stress analysis method. Materials and Methods: A three dimensional implant, abutment (zirconia and titanium), abutment screw, crown (zirconia reinforced lithium silicate, lithium disilicate, polymer-infiltrated resin ceramic, and PEEK), and alveolar bone were designed using Rhinoceros 3D modeling software and VRMesh Studio software and combined to form 8 simulations. On the models prepared, loading was made on the lingual tubercule of the maxillary right first premolar crown at an angle of 30° with 150 N force obliquely in the buccolingual direction. The von Mises values obtained from the abutment screw were compared according to the types of abutment and crown materials. Results: The von Mises stress values in the abutment screw were higher in the models using a titanium abutment abutment (on average 1336.24 MPa), and the lower stress values were obtained in the models using a zirconia abutment (on average 964.26 MPa). When the prosthetic material used was changed, no apparent difference was observed in the stress values on the abutment screw. Conclusions: Considering that the abutment screw is the weakest link of the implant system, zirconia abutments can be used reliably in the maxillary first premolar region where aesthetic expectations are high.

Esthetic patient satisfaction, marginal bone loss and peri-implant tissue success in esthetic zone: systematic review

Increased patient demands for highly esthetic implant superstructure in the anterior esthetic zone has increased inthe last decades. Moreover, the absence of periodontal ligament in implant supported prosthesis causes forces tobe transferred without cushioning effect to the alveolar bone, resulting in increased marginal bone loss (MBL) andinfluence the heath of peri-implant tissue. Evaluate the available evidence on the effect implant superstructure andit consequences on patient satisfaction, MBL, bleeding on probing (BOP) and probing depth (PD). A protocol ofelectronic and hand research was performed for English based researches comparing implants inserted in the estheticzone with all ceramic superstructure: “Will the use of different types of all ceramic superstructure show differentesthetic patient satisfaction, marginal bone loss, bleeding on probing and probing depth? Thirteen publicationsfrom one thousand one hundred and sixteen research studies were included. This systematic review showed that allceramic implant superstructure was a versatile treatment option with higher esthetic patient satisfaction and bettercolor of peri-implant mucous especially in patients having thin biotype. On the other hand there wasn’t significantdifference in MBL, PD and BOP compared to other conventional implant superstructure. More randomized controlledclinical trials with bigger samples are needed to confirm our findings. All ceramic implant superstructure is versatileand highly esthetic treatment option for implant placed in the anterior esthetic zone.KEYWORDSEsthetic; Patient satisfaction; Tissue success; Marginal bone loss; Superstructure.

Six-year clinical outcomes of implant-supported acrylic vs. ceramic superstructures according to the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla

The aim of the current study was to document the long-term clinical results of the use of two prosthetic techniques for the rehabilitation of completely edentulous maxillae according to the “All-on-Four” concept: Fixed, screw-retained prosthesis mounted on a chrome-molybdenum framework with (1) metal-ceramic veneers and (2) Acrylic prosthesis with acrylic resin prosthetic teeth. A total of 34 patients were assigned to subgroups according to their own preference of the superstructure type (ceramics [n: 17] or acrylic resin [n: 17]). Prosthetic complications, marginal bone loss, plaque accumulation, bleeding on probing, bite force and oral-health-related quality of life were assessed over a period of 6 years. Marginal bone loss around implants of the ceramic group remained well within the limits for ‘success’, as defined by the 2007 Pisa consensus over the time (1.43 ± 0.35 mm). However, marginal bone loss was significantly more pronounced around the implants in the acrylic group (2.15 ± 0.30) and the difference between two groups was statistically significant (p: 0.00). Bleeding on probing and plaque accumulation showed also positive correlation with marginal bone loss. Both acrylic and ceramic suprastructures appeared to be equivalent after 6 years; however, ceramic suprastructures revealed superior clinical results in terms of bone loss and plaque accumulation. Current study determines the long-term clinical outcomes of different prosthetic management alternatives in All-on-Four and aids to increase dental professionals’ ability to meet the patients’ expectations.

A technique for separating a ceramic implant-supported restoration from a titanium base abutment

Titanium base abutments or titanium inserts provide a metal implant connection for computer-aided design and computer-aided manufacture (CAD-CAM) fabricated screw-retained implant-supported ceramic restorations.1 These ceramic superstructures are usually cemented to the titanium base abutment extraorally with definitive resin cements.

Tensile Bond Strength of Three Custom-made Tooth-Colored Implant Superstructures to Titanium Inserts

Statement of the Problem: Hybrid abutments are made of a titanium implant insert and a ceramic component. The tensile bond strength between the titanium implant insert and the ceramic component is not still clearly known. Purpose:This in vitro study aimed to compare the tensile bond strength of the titanium insert to ceramic components made of milled lithium disilicate, milled zirconia, and pressable lithium disilicate. Materials and Method: To standardize the shape and dimension of the ceramic components, a single computer-aided design/computer assisted manufacturing (CAD/CAM) superstructure was designed with Dental Designer software. Based on this model, CAD milled zirconia (Zr), CAD milled Lithium disilicate (CAD-LD) and heat-pressed lithium-disilicate (H-LD) superstructures were fabricated (n=10 per group). They were bonded to the titanium inserts by using self-adhesive resin cement. The prepared superstructure-titanium insert complexes (hybrid abutments) were screwed into the implants with 35 Ncm torque. The tensile bond strength of the ceramic superstructures to the titanium inserts were recorded by the universal testing machine with a crosshead speed of 2 mm/min. The data were analyzed by using one-way ANOVA and Tamhane post-hoc test (p< 0.05). Results:The mean±SD of tensile bond strength was 328.50±30.4 N in CAD-LD, 257.30±23.8 N in H-LD, and 242.20±21.2 N in Zr groups. One-way ANOVA revealed the groups significantly different in terms of the tensile bond strength (p< 0.001). Tamhane post-hoc test showed a significant difference between the CAD-LD and the two other groups (p<0.001); however, no statistically significant difference was detected between the H-LD and Zr groups (p= 0.39). Conclusion:It can be concluded that the CAD-LD has higher bond strength to titanium insert compared with the H-LD and Zr groups. Therefore, they might be clinically more beneficial in high-esthetic areas.

MARGINAL ADAPTATION OF VARIOUS CAD/CAM ALL-CERAMIC SUPERSTRUCTURES CEMENTED ON READY AND CUSTOM MADE ZIRCONIA ABUTMENTS

Statement of the problem: In spite of the varied materials and techniques available for fabricating implant-supported superstructures, reaching an abutment/crown combination that provides standardized results and an accurate fit is still of utmost importance for the success of implant-supported restorations.Purpose of the study: This study aimed to evaluate the marginal adaptation of various CAD/CAM fabricated all-ceramic superstructures cemented on both ready and custom made zirconia abutments.Materials and methods: A total of 30 implant samples were divided into two main groups (n=15) according to the received zirconia abutment design as follows; Group I: readymade zirconia abutments with scalloped 0.5 mm chamfer finish line and Group II: custom made zirconia abutments with uniform 1mm deep chamfer finish line. According to the received ceramic superstructure material each group was further subdivided into three subgroups (n=5) namely; subgroup1: Vita Enamic, subgroup2: IPS e. max CAD and subgroup3: Zirconia. Vertical marginal gap measurements for different groups were carried before cementation using a digital microscope; measurements were repeated again after cementation of the superstructures each on its corresponding abutment. Data were statistically analyzed. Results: Regardless of ceramic superstructure material or cementation, it was found that the ready-made abutments recorded a statistically significant higher mean vertical marginal gap than the custom made abutments. Regardless of abutment designs or superstructure material; it was found that there was a statistically significant increase in mean marginal gap distance after cementation at P-value ≤ 0.05.Conclusions: Based on the clinical acceptability of 120 μm as a marginal gap, the results of the three all-ceramic superstructures were within the acceptable range for both tested abutments. Marginal gap values increased after cementation of various superstructures on different abutments.

Three-Dimensional Accuracy of CAD/CAM Titanium and Ceramic Superstructures for Implant Abutments Using Spiral Scan Microtomography

To introduce a new three-dimensional (3D) method of evaluating the fit of implant superstructures made using computer-aided design/computer-assisted manufacture (CAD/CAM) technology and conventional casting and to determine which biomaterial would produce optimal fit for the long-term clinical longevity of dental implant restorations. Five groups of materials were used to make 50 copings (n = 10) using CAD/CAM technology for titanium, partially sintered zirconia, fully sintered zirconia, and leucite-reinforced glass-ceramic materials and a conventional casting technique for the nickel-chromium group. The vertical marginal gap was measured at 16 equidistant points using a traveling microscope and compared with the 3D spatial gap values obtained by using spiral scan microtomography. Multivariate analysis of variance and Tukey post hoc tests were used for statistical analysis. The vertical marginal gap width ranged from 13.21 to 75.26 μm for the CAD/CAM groups and 64.89 to 115.27 μm for the conventionally casted group. The spatial gap ranged from 0.22 to 0.67 mm3 for CAD/CAM groups and 0.75 to 0.89 mm3 for the conventionally casted group. The highest accuracy of fit was observed in the titanium group, followed by the leucite-reinforced glass-ceramic, partially sintered zirconia, fully sintered zirconia, and nickel-chromium groups. When used in combination with the CAD/CAM technique, titanium produces the most accurate implant superstructure. Spiral scan microtomography can be used to measure the accuracy of fit of dental implant superstructures and restorations as it provides a 3D measurement with less chance of errors compared with conventional methods of measurement.

High temperature zirconia oxygen sensor with sealed metal/metal oxide internal reference

Potentiometric internal reference oxygen sensors are created by embedding a metal/metal oxide mixture within a yttria-stabilized zirconia oxygen-conducting ceramic superstructure. Three metal/metal oxide systems based on Pd, Ni, and Ru are examined. A static internal reference oxygen pressure is produced inside the reference chamber of the sensor at the target application temperature. The metal/metal oxide-containing reference chamber is sealed within the stabilized zirconia ceramic superstructure by a high pressure (3–6 MPa) and high temperature (1200–1300 °C) bonding method that initiates grain boundary sliding between the ceramic components. The bonding method creates ceramic joints that are pore-free and indistinguishable from the bulk ceramic. The Pd/PdO-based oxygen sensor presented in this study is capable of long-term operation and resistant to the strains of thermal cycling. The current temperature limit of the device is limited at 800 °C. As the sensor does not require reference gas plumbing there is flexibility in placement of sensors in a combustion stream. Furthermore, the sensor assembly process readily lends itself to miniaturization.

Fit of titanium and a base metal alloy metal-ceramic crown

Statement of problem. Titanium has been widely used in dental implantology. However, problems remain for use of titanium in prosthodontics. Purpose. This study evaluated the marginal and inner fit of metal-ceramic restorations and frameworks made with a nickel-chromium alloy (Remanium CS) and a commercially pure titanium (Rematitan). Fit was compared with SEM before and after firing of ceramic materials. Material and methods. Sixteen metal frameworks were cast with each casting material, 8 frameworks were used directly to evaluate measurements for fit (RCS: Remanium CS frameworks and TI: Rematitan frameworks). Porcelain was applied on the other 8 frameworks (RCSP: Remanium CS-porcelain and TIP: Rematitan-porcelain), fired, and then the fit was measured. Measurements were recorded at 3 points for marginal fit evaluation and at 3 points for inner fit. Results. Significant differences were recorded among the occlusal (JK) values of groups tested ( P <.05). Marginal fit and inner fit of Remanium CS frameworks were better than Rematitan frameworks. However, there were no substantial differences detected among groups after firing the ceramic superstructures. Conclusion. The fit of the base metal alloy metal-ceramic crowns was better than the commercially pure titanium metal-ceramic crowns. However, both artificial crowns were clinically acceptable. (J Prosthet Dent 2000;83:314-8.)

A double cast fixed detachable prosthesis for the correction of severely angulated implants

Unfavorable angulation of dental implants is a common complication that may make the design of the prosthetic device difficult and may compromise its function, access for oral hygiene procedures, and esthetic appearance. When the use of angulated abutments makes the prosthetic design unacceptable, the use of a double cast fixed detachable prosthodontic procedure may be required, which includes a cast substructure retained with conventional set screws to support a cast metal ceramic superstructure retained by semiprecision attachments and friction. This procedure improves access for oral hygienic procedures and offers better control over the esthetics and the function of the restoration.