Maxillary cement retained implant supported monolithic zirconia prosthesis in a full mouth rehabilitation: a clinical report

Do all ceramic and composite CAD-CAM materials exhibit equal bonding properties to implant Ti-base materials? An Interfacial Fracture Toughness Study

OBJECTIVES

To compare the interfacial fracture toughness (IFT) with or without aging, of four different classes of CAD-CAM ceramic and composite materials bonded with self-adhesive resin cement to titanium alloy characteristic of implant abutments.

METHODS

High translucent zirconia (Katana; KAT), lithium disilicate-based glass-ceramic (IPS. emax.CAD; EMX), polymer-infiltrated ceramic network material (PICN) (Vita Enamic; ENA), and dispersed filler composite (Cerasmart 270; CER) were cut into equilateral triangular prisms and bonded to titanium prisms with identical dimensions using Panavia SA Cement Universal. The surfaces were pretreated following the manufacturers' recommendations and developed interfacial area ratio (Sdr) of the pretreated surfaces was measured. IFT was determined using the Notchless Triangular Prism test in a water bath at 36 °C before and after thermocycling (10,000 cycles) (n = 40 samples/material).

RESULTS

IFT of the materials ranged from 0.80 ± 0.25 to 1.10 ± 0.21 MPa.m1/2 before thermocycling and from 0.71 ± 0.24 to 1.02 ± 0.25 MPa.m1/2 after thermocycling. There was a statistical difference between IFT of CER and the two top performers in each scenario: KAT and EMX before aging, and KAT and ENA after aging. Thermocycling significantly decreased IFT of EMX. The Weibull modulus of IFT was similar for all materials and remained so after thermocycling. Sdr measurements revealed that ENA (7.60)>Ti (4.97)>CER (2.85)>KAT (1.09)=EMX (0.96).

SIGNIFICANCE

Dispersed filler CAD-CAM composite showed lower performance than the other materials. Aging only affected IFT of Li-Si glass-ceramic, whereas zirconia and PICN performed equally well, probably due to their chemical bonding potential and surface roughness respectively.

Clinical performance of full-arch implant-supported fixed restorations made of monolithic zirconia luted to a titanium bar: A retrospective study with a mean follow-up of 16 months

OBJECTIVES

This retrospective case series aimed to evaluate the short-term clinical advantages and limitations of full-arch implant-supported restorations made of monolithic zirconia suprastructures passively luted to titanium bar infrastructures and to report the rate of complications within a minimum of 1-year follow-up.

MATERIALS AND METHODS

This study included 31 patients (19 men and 12 women) requiring full-arch implant-supported prostheses in the upper or lower jaw. The patients were treated using an entirely digital approach from implant planning and guided implant placement to prosthetic construction planning, design, and fabrication. Full-arch implant-supported monolithic zirconia suprastructures luted to prism-shaped titanium bars were used in all the cases. All the restorations were evaluated for biological and technical complications during fixed control appointments.

RESULTS

No implant failures or serviceable prosthetic complications were reported, and the prosthetic survival rate was 100%, with a follow-up duration ranging from 12 months to 20 months. In two cases, a fracture line was observed in the zirconia suprastructures, although it did not require any intervention.

CONCLUSIONS

After a 16-month mean follow-up period, the monolithic zirconia implant-supported full-arch fixed dental prostheses demonstrated no biological or technical complications. Further clinical studies with long-term results are required to confirm these reported outcomes.

CLINICAL SIGNIFICANCE

CAD-/CAM-milled monolithic zirconia structures passively luted to titanium bar infrastructures are a viable treatment option for full-arch restorations over implants, demonstrating 100% survival and success rates in the present study. The outcomes of this short-term retrospective study indicated high success in function, aesthetics, phonetics, and the ability to maintain flawless hygiene. However, the long-term results of restorations produced using the proposed technique should be considered before recommending this approach for routine clinical use.

Biaxial flexural strength and phase transformation characteristics of dental monolithic zirconia ceramics with different sintering durations: An in vitro study

STATEMENT OF PROBLEM

Zirconia is a polymorphic metastable material which can react through a phase transformation from tetragonal to monoclinic when exposed to mechanical, physical, or chemical stimuli.

PURPOSE

The purpose of this in vitro study was to investigate the fracture strength and phase structure of different high-translucency zirconia ceramics depending on the changes in sintering duration and thermocycling.

MATERIAL AND METHODS

Two monolithic zirconia ceramics, Katana (KAT) and NexxZr (NEX), were used to prepare disk-shaped specimens (n=66). The sintering temperature was 1500 °C, and 3 different sintering durations were tested: 1 hour, 2 hours (recommended by the manufacturer), and 3 hours. Thermocycling was applied to half the specimens. Fracture strength was calculated, and the specimens were analyzed with an X-ray diffractometer (XRD) to determine the level of the phase transformation. The normal distribution of the data was analyzed by using the Shapiro-Wilk test. Two-way ANOVA was used to compare multiple groups (α=.05). The Fisher least significant difference test was applied to identify significant differences in fracture strength. The paired-specimen t test was applied to perform intragroup comparisons.

RESULTS

Sintering duration significantly affected the fracture strength of KAT (P=.007). For nonthermocycled specimens, the fracture strength of NEX was significantly higher than that of KAT (P<.001). Thermocycling had a significant effect on fracture strength depending on sintering duration and zirconia ceramic interaction (P=.046).

CONCLUSIONS

The sintering duration only affected the KAT zirconia, and the fracture strength of KAT decreased when sintered for 3 hours. Thermocycling decreased the fracture strength of both zirconias, except when the sintering duration was 2 hours for NEX. The fracture strength was higher for NEX than for KAT. Tetragonal-monoclinic phase transformation was not found for either zirconia according to the XRD analysis.

Effects of sintering time on translucency and color of translucent zirconia ceramics

OBJECTIVE

To investigate the effect of sintering time on translucency and color of translucent zirconia ceramics.

MATERIALS AND METHODS

Sixty translucent zirconia (5Y-TZP) specimens (12 × 1.6 mm, Katana (KAT) and NexxZr (NEX)) were divided into six groups (n = 10) according to sintering time; 1, 2 (specified by manufacturer-control), and 3 hs. Color differences (ΔEab) within same material when sintered using different times and between materials when same sintering time was used were calculated, as well as translucency parameters (TP) after the use of each sintering time. Data for ΔEab and TP were analyzed with two-way ANOVAs, pairwise comparisons, and Fisher's LSD Test (Post-hoc).

RESULTS

When 1 or 3 h were used, color difference from the color of specimens when manufacturer-specified time (2 h) was used was similar for both KAT and NEX. ΔEab values of NEX were significantly higher than KAT when sintered for 1 or 3 h (P < 0.001). TP increased for KAT when sintered for 1 h, and was higher than NEX. TP for NEX increased when sintered for 3 h (P < 0.001), but was not significantly different than that of KAT.

CONCLUSIONS

Effect of 1 or 3-h sintering on color was similar for both zirconias. For NEX, this effect resulted in greater differences from the color of specimens when manufacturer-specified time was used. Sintering for 1 h increased the translucency of KAT.

CLINICAL SIGNIFICANCE

When high translucency is desired, clinicians may prefer 1-h sintering for KAT zirconia. When lower translucency is desired, 3-h sintering for NEX can be used. However, for NEX, the color after 1- or 3-h sintering was different than the color obtained with manufacturer-specified time, and this difference may affect the final color of restoration compared to the final color when manufacturer-specified time is used.

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.

Retrospective 2- to 7-Year Follow-Up Study of 20 Double Full-Arch Implant-Supported Monolithic Zirconia Fixed Prostheses: Measurements and Recommendations for Optimal Design

PURPOSE

To measure the extension of cantilever lengths, thicknesses, and heights of zirconia prostheses in the lingual and facial areas of the distal screw access openings, and to evaluate the clinical performance regarding chipping or fracture of the distal cantilevered sections of double full-arch CAD/CAM screw-retained, stained, monolithic zirconia, gingival-colored ceramic implant-supported fixed prostheses (MZ-FPs).

MATERIALS AND METHODS

Ten edentulous patients were provided with a total of 20 CAD/CAM double full-arch MZ-FPs. The zirconia thicknesses around distal screw access openings at three different levels (crown height space, screw access opening lengths, and dimensions of the cantilevered segments) were measured in the resin prototypes. Patients were evaluated clinically (visually) without magnification, with intraoral digital photography, and radiologically by the author, approximately every 6 months. Ten patients with 20 MZ-FPs were evaluated. Twenty resin prototypes with 35 cantilevered segments (15 maxillary, 20 mandibular) were measured. The lingual and facial thicknesses of the resin frameworks and the crown height spaces of 35 distal access openings were measured.

RESULTS

The average extension of the maxillary cantilever segments was 7.72 mm; the mandibular cantilever average was 13.72 mm. The average crown height space for maxillary prostheses was 13.27 mm, for the mandibular prostheses it was 11.89 mm. Zirconia thickness around distal screw access openings at the middle of the crowns, margins and middle of the gingival areas (buccal side of maxillary prostheses) was 4.29, 3.79, and 3.87 mm, respectively. On the lingual sides the thicknesses were 3.13, 2.85, and 3.15 mm, respectively. For mandibular prostheses the thicknesses were 3.56, 3.08, and 3.15 mm, respectively, on the buccal sides, and 2.07, 2.00, and 2.99 mm, respectively, on the lingual sides. No implant failure or changes in the occlusal surface, chipping of the cuspid or incisal edges, or prosthesis distal extension fractures were observed during follow-up periods ranging from 2 to 7 years. The survival rate was 100% for implants and prostheses. In one of the patients, chipping of the pink ceramic was noted in the maxillary prosthesis 36 months after placement.

CONCLUSIONS

The results of this study indicated that full-arch MZ-FPs without cutback, or with partial digital cutback and veneering ceramic, were a therapeutic option. Recommendations regarding the thickness of zirconia at the level of the distal screw access openings, the crown height spaces, and the lengths of the cantilever segments were recorded. Additional in vitro and clinical studies will be required for more scientific analysis of the criteria for design of this type of prosthesis to minimize prosthetic complications. Long-term and multicenter studies are needed to corroborate the findings discussed in this report.

Shear bond strength of indirect composite material to monolithic zirconia

PURPOSE

This study aimed to evaluate the effect of surface treatments on bond strength of indirect composite material (Tescera Indirect Composite System) to monolithic zirconia (inCoris TZI).

MATERIALS AND METHODS

Partially stabilized monolithic zirconia blocks were cut into with 2.0 mm thickness. Sintered zirconia specimens were divided into different surface treatment groups: no treatment (control), sandblasting, glaze layer & hydrofluoric acid application, and sandblasting + glaze layer & hydrofluoric acid application. The indirect composite material was applied to the surface of the monolithic zirconia specimens. Shear bond strength value of each specimen was evaluated after thermocycling. The fractured surface of each specimen was examined with a stereomicroscope and a scanning electron microscope to assess the failure types. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey LSD tests (α=.05).

RESULTS

Bond strength was significantly lower in untreated specimens than in sandblasted specimens (P<.05). No difference between the glaze layer and hydrofluoric acid application treated groups were observed. However, bond strength for these groups were significantly higher as compared with the other two groups (P<.05).

CONCLUSION

Combined use of glaze layer & hydrofluoric acid application and silanization are reliable for strong and durable bonding between indirect composite material and monolithic zirconia.

Complete-arch implant-supported monolithic zirconia fixed dental prostheses: A systematic review

STATEMENT OF PROBLEM

Monolithic zirconia prostheses are emerging as a promising option in the implant-based rehabilitations of edentulous patients, yet their clinical performance is not fully documented.

PURPOSE

The purpose of this systematic review was to assess the clinical performance of complete-arch implant-supported monolithic zirconia fixed dental prostheses.

MATERIAL AND METHODS

The electronic databases PubMed, Science Direct, and Cochrane Library were searched for clinical studies on complete-arch implant-supported monolithic zirconia fixed dental prostheses. Human studies with a mean follow-up of at least 1 year and published in an English-language peer-reviewed journal up to June 2015 were included. Two independent examiners conducted the search and the review process.

RESULTS

The search generated 903 titles. Eighteen qualifying studies were retrieved for full-text evaluation. Nine studies were included on the basis of preestablished criteria. Eight studies reported satisfactory clinical and esthetic outcomes. One study demonstrated prosthesis failure. Clinical studies are lacking on the long-term outcome of complete-arch implant-supported monolithic zirconia prostheses.

CONCLUSIONS

Complete-arch dental implant restoration with monolithic zirconia is associated with high short-term success. Despite the many advantages and short-term favorable reports, studies of longer duration are necessary to validate the broad application of this therapy.

Retrospective analysis of 26 complete-arch implant-supported monolithic zirconia prostheses with feldspathic porcelain veneering limited to the facial surface

STATEMENT OF PROBLEM

Monolithic zirconia prostheses on teeth or implants have been proposed in recent years as a potential treatment. To date, limited data regarding the outcomes of these prostheses have been presented and are mainly based on limited sample size and short-term follow-up. Data on complete-arch monolithic zirconia prostheses are relatively scarce.

PURPOSE

The purpose of this retrospective study was to evaluate the clinical performances of 26 implant-supported, complete-arch, monolithic zirconia restorations with facial feldspathic porcelain veneers for the rehabilitation of completely edentulous patients.

MATERIAL AND METHODS

All patients' charts from 2 private practices from 2010 to 2013 were reviewed. Patients rehabilitated with a complete-arch implant-supported monolithic zirconia prostheses were included in the study. Several parameters were recorded so as to evaluate the outcome of these rehabilitations: implant survival and success rates, prosthesis survival rate, interproximal bone loss, periimplant probing depth, and bleeding on probing. The number and type of prosthetic complications were also recorded. Data were analyzed with descriptive statistics.

RESULTS

Eighteen patients were treated with a total of 26 complete-arch fixed prostheses. The mean follow-up time was 20.9 months (SD 13.6; range, 10 to 36 months). In total, 154 implants were placed supporting 309 retainers and pontics. The implant survival rate was 100% and the success rate was 94.8%. Mean bone loss was 0.66 mm (SD 0.59 mm). Mean probing depth was 3.4 mm (SD 0.92 mm). Bleeding on probing was positive in 19% of probing sites. The prosthesis survival rate was 100%.

CONCLUSIONS

The results of this retrospective evaluation showed that monolithic zirconia restorations with facial porcelain veneer provided satisfactory clinical performance and suggest that these rehabilitations are a viable treatment option for completely edentulous patients.

Clinical Advantages and Limitations of Monolithic Zirconia Restorations Full Arch Implant Supported Reconstruction: Case Series

Purpose. The purpose of this retrospective case series is to evaluate the clinical advantages and limitations of monolithic zirconia restorations for full arch implant supported restorations and report the rate of complications up to 2 years after insertion. Materials and Methods. Fourteen patients received implant placement for monolithic zirconia full arch reconstructions. Four implants were placed in seven arches, eleven arches received six implants, two arches received seven implants, two arches received eight implants, and one arch received nine implants. Results. No implant failures or complications were reported for an implant survival rate of 100% with follow-up ranging from 3 to 24 months. Conclusions. Monolithic zirconia CAD-/CAM-milled framework restorations are a treatment option for full arch restorations over implants, showing a 96% success rate in the present study. Some of the benefits are accuracy, reduced veneering porcelain, and minimal occlusal adjustments. The outcome of the present study showed high success in function, aesthetics, phonetics, and high patient satisfaction.