Markus B. Blatz

An in vitro evaluation of the long-term resin bond to a new densely sintered high-purity zirconium-oxide ceramic surface

STATEMENT OF PROBLEM Successful long-term bonding to zirconia ceramic remains a challenge, requiring special cements and surface roughening by airborne-particle abrasion, which might negatively affect the ceramic. PURPOSE The purpose of this study was to evaluate the shear bond strength (SBS) of composite resin cylinders to a modified zirconia surface using different luting techniques after thermal cycling. MATERIAL AND METHODS Composite resin (TPH3) cylinders with a diameter of 3 mm were bonded to zirconia ceramics (Procera Zirconia) with a modified surface (RZ) and a machined surface (MZ). Three different adhesive luting cements (Panavia F2.0, RelyX ARC, RelyX Unicem) in combination with and without airborne-particle abrasion (50-microm and 110-microm Al(2)O(3)) were used. RZ was bonded using all 3 cements with (50 mum) and without airborne-particle abrasion; with 110 microm, only Panavia F2.0 was used. MZ was bonded using only Panavia F2.0 with (50 microm, 110 microm) and without airborne-particle abrasion. SBS was tested in a universal testing machine (Instron) before and after 90 days of water storage and 20,000 thermal cycles (dwell time, 15 seconds). Statistical analysis was performed using a multifactorial ANOVA model with alpha=.05. RESULTS Mean SBS ranged from 10.1 to 20.0 MPa after 3 days and from 0.16 to 14.8 MPa after thermal cycling. Thermal cycling decreased SBS significantly. Airborne-particle abrasion significantly decreased SBS to the modified surface, regardless of cements used. SBS to the modified zirconia surface was significantly higher than to the machined surface. CONCLUSIONS SBS to the modified zirconia surface is higher than to airborne-particle-abraded, machined zirconia. Airborne-particle abrasion of the modified zirconia surface is not recommended.

A comparison of bond strength of layered veneering porcelains to zirconia and metal.

STATEMENT OF PROBLEM High chipping rates of veneering porcelain for zirconia ceramic restorations have been reported in clinical studies. The information on the bonding behavior of veneering porcelain to zirconia frameworks is limited. PURPOSE This study assessed the relationship between coefficient of thermal expansion (CTE) and shear bond strength of veneering porcelain to zirconia frameworks. MATERIAL AND METHODS Zirconia ceramics (Katana; ZrO(2)), casting gold alloy (DeguDent U; DEG), and feldspathic porcelain (Cerabien ZR; CZR) were used as the bonding substrates. Five types of porcelain (CZR, Cercon ceramkiss (CER), IPS e.max Ceram (EMX), Vintage ZR (VZR), and VITA VM 9 (VM9)) were fired to ZrO(2) discs (n=8). Feldspathic porcelain (Super Porcelain AAA; AAA) designed for metal ceramic systems was fired to DEG discs. To evaluate the strength of veneering porcelain, CZR was veneered on CZR discs. The porcelain with a strong thermal mismatch for each substrate was applied; AAA and CZR were applied to ZrO(2) and DEG substrates, respectively. Shear bond strength was tested after 24 hours of water storage. Debonded surfaces were examined with an optical microscope and SEM. Data were analyzed with 1- and 2-way ANOVA followed by Dunnett and Tukey multiple comparison tests (α=.05). RESULTS No significant differences in the mean shear bond strength (MPa) were found between groups ZrO(2)-VZR (24.8), ZrO(2)-CZR (27.0), and ZrO(2)-VM9 (30.9). ZrO(2)-CER (22.0) (P=.017) and -EMX (22.1) (P=.020) groups had significantly lower bond strengths than the ZrO(2)-CZR group. ZrO(2)-CZR, -VM9, -CER, -VZR, and -EMX groups demonstrated cohesive failures in veneering porcelain. There was no significant difference among the groups ZrO(2)-CZR, DEG-AAA, and CZR-CZR. Two-way ANOVA showed that interaction between the 2 factors was significant (P<.001). CONCLUSIONS Strong discrepancies in CTE between veneering porcelains and zirconia significantly affect their bond strength.

Precision of fit of implant‐supported screw‐retained 10‐unit computer‐aided‐designed and computer‐aided‐manufactured frameworks made from zirconium dioxide and titanium: an in vitro study

OBJECTIVE To analyze the precision of fit of implant-supported screw-retained computer-aided-designed and computer-aided-manufactured (CAD/CAM) zirconium dioxide (ZrO) frameworks. MATERIALS AND METHODS Computer-aided-designed and computer-aided-manufactured ZrO frameworks (NobelProcera) for a screw-retained 10-unit implant-supported reconstruction on six implants (FDI positions 15, 13, 11, 21, 23, 25) were fabricated using a laser (ZrO-L, N = 6) and a mechanical scanner (ZrO-M, N = 5) for digitizing the implant platform and the cuspid-supporting framework resin pattern. Laser-scanned CAD/CAM titanium (TIT-L, N = 6) and cast CoCrW-alloy frameworks (Cast, N = 5) fabricated on the same model and designed similar to the ZrO frameworks were the control. The one-screw test (implant 25 screw-retained) was applied to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from approximal and buccal values. Statistical comparison was performed with non-parametric tests. RESULTS No statistically significant pairwise difference was observed between the relative effects of vertical microgap between ZrO-L (median 14 μm; 95% CI 10-26 μm), ZrO-M (18 μm; 12-27 μm) and TIT-L (15 μm; 6-18 μm), whereas the values of Cast (236 μm; 181-301 μm) were significantly higher (P < 0.001) than the three CAD/CAM groups. A monotonous trend of increasing values from implant 23 to 15 was observed in all groups (ZrO-L, ZrO-M and Cast P < 0.001, TIT-L P = 0.044). CONCLUSIONS Optical and tactile scanners with CAD/CAM technology allow for the fabrication of highly accurate long-span screw-retained ZrO implant-reconstructions. Titanium frameworks showed the most consistent precision. Fit of the cast alloy frameworks was clinically inacceptable.

Bonding of resin-based luting cements to zirconia with and without the use of ceramic priming agents.

PURPOSE This study evaluated and compared bonding characteristics of resin-based luting agents and special ceramic primers to zirconia. MATERIALS AND METHODS Disk specimens (n = 242) were fabricated from zirconium dioxide ceramics (Katana) and bonded with four resin-based luting agents without priming. In addition, zirconia was bonded with 7 bondingsystem combinations of three priming agents and three resin-based luting agents. Two of the resin-based luting agents and two ceramic priming agents contain an identical adhesive monomer, 10-methacryloyloxydecyl dihydrogen phosphate (MDP), either in the material itself or in the priming agent. Shear bond strength was determined after 20,000 cycles of thermocycling. The Kruskal-Wallis test was performed for both pre- and post-thermocycling groups to evaluate the difference among primer and luting agent variations. On the basis of the Kruskal-Wallis test, Steel-Dwass multiple comparisons were further performed to compare the difference among four luting agents and seven conbinations of three primers and three luting agents for both pre- and post-thermocycling conditions. RESULTS Within the four unprimed groups, Clearfil SA Cement (5.8 MPa) and Panavia F 2.0 (6.7 MPa) showed statistically higher post-thermocycling bond strength than the other materials (0.1 MPa) (p < 0.05). Among the seven primer/cement combinations, Clearfil Ceramic Primer combined with Clearfil Esthetic Cement exhibited the highest post-thermocycling bond strength (7.5 MPa), followed by two groups primed with Monobond Plus (4.0-4.6 MPa) (p < 0.05). CONCLUSION Application of resin-based luting and priming agents containing the adhesive monomer MDP provide better bond strength to zirconia than do other systems.

Influence of contamination and cleaning on bond strength to modified zirconia

OBJECTIVE To evaluate the influence of contamination and cleaning procedures on shear bond strength (SBS) to modified zirconia surfaces. METHODS One hundred zirconium-oxide ceramic disks fabricated with a rough modified surface (Nobel Bond), which allows more micromechanical interlocking for adhesive cementation, were divided into five groups. Groups were contaminated with organic (OC; human blood and saliva) and/or inorganic contaminants (IC; type IV dental stone). For cleaning, modified surfaces were etched with phosphoric acid for 1min (PA) or fired in a ceramic furnace up to 910 degrees C and cleaned in an ultrasonic bath in ethanol (FU). Following combinations of contamination and cleaning protocols were chosen: group 1: OC-PA; group 2: IC-FU; group 3: OC+IC-PA+FU; group 4: OC+IC-no cleaning; group 5: no contamination-no cleaning. Level of contamination and efficacy of cleaning were evaluated using X-ray photoelectron spectroscopy (XPS). Composite cylinders were bonded to the disks using dual curing adhesive resin cement (RelyX ARC). Fifty samples were subjected to 20,000 thermal cycles (TC). All samples were tested for SBS. Statistical analysis was performed using one-way ANOVA with alpha=0.05. RESULTS SBS ranged from 16.6 to 18.8MPa (non-TC) and 10.6-21.7MPa (TC). TC did not lower SBS, except for group 1. XPS showed that OC produced higher levels of carbon, nitrogen, and silica, whereas IC generated elevated levels of calcium, sulfur, carbon, and potassium. Cleaning with both procedures reduced contamination significantly. SIGNIFICANCE A combination of FU and PA is an efficient method for cleaning contaminated modified zirconia surfaces.

Resin Bond to Indirect Composite and New Ceramic/Polymer Materials: A Review of the Literature

STATEMENT OF THE PROBLEM Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites. PURPOSE OF THE STUDY The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials. MATERIALS AND METHODS An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials. RESULTS The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage. CONCLUSIONS Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials. CLINICAL SIGNIFICANCE This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required.

Zirconia Abutments for Single-Tooth Implants—Rationale and Clinical Guidelines

Clinical success of an endosseous implant to replace a single tooth is not only defined by its survival. Esthetic parameters have become integral aspects in defining success and failure. All-ceramic abutments have started to play a major role in achieving an esthetically successful result. The material itself, however, is not the exclusive determinant for esthetic success. It is the appropriate design and proper handling of the material and the abutment that enables the clinician to achieve esthetic outcomes that were not possible with traditional metal alloys. This article explores the rationale for using zirconia for prosthetic implant components, explains specific material properties, and discusses strategies and guidelines for the design and successful clinical implementation of CAD/CAM-fabricated zirconia implant abutments.

Laser therapy may be better than topical desensitizing agents for treating dentin hypersensitivity.

Article Title and Bibliographic Information Effectiveness of laser therapy and topical desensitising agents in treating dentine hypersensitivity: a systematic review. He S, Wang Y, Li X, Hu D. J Oral Rehabil 2011;38(5):348-58. Reviewer Markus B. Blatz, DMD, PhD, Dr med dent habil Purpose/Question To determine the effectiveness of laser therapy as compared with topical desensitizing agents for the treatment of patients with dentin hypersensitivity and the safety of laser application based on the relevant studies Source of Funding Information not available Type of Study/Design Systematic review Level of Evidence Level 2: Limited-quality, patient-oriented evidence Strength of Recommendation Grade Grade B: Inconsistent or limited-quality patient-oriented evidence

Adhesive bonding of zirconia with single-liquid acidic primers and a tri-n-butylborane initiated acrylic resin.

PURPOSE The purpose of the current study was to evaluate the effect of acidic primers on the bond strength and durability of an acrylic resin luting agent to zirconia. MATERIALS AND METHODS Disk specimens were fabricated from zirconia partially stabilized with yttrium oxide (Katana, Noritake Dental Supply). The disks were treated with one of the following acidic primers: Acryl Bond (Shofu), All Bond II Primer B (Bisco), Alloy Primer (Kuraray), Estenia Opaque Primer (Kuraray), Eye Sight Opaque Primer (Kanebo), M.L. Primer (Shofu), MR. Bond (Tokuyama Dental), or Super-Bond Liquid (Sun Medical). Unprimed specimens served as the control. The disks were bonded with a tri-n-butylborane (TBB)-initiated acrylic resin. Shear bond strengths were determined both before and after 10,000 thermocycles (5°C and 55°C, 1 min dwell time each). RESULTS The pre-thermocycling bond strength ranged from 0.7 MPa to 30.8 MPa, whereas post-thermocycling bond strength varied from 0.3 MPa to 17.6 MPa. The significantly highest post-thermocycling bond strength was obtained when using the Alloy Primer and Estenia Opaque Primer agents. CONCLUSION Within the limitations of the current experiment, it can be concluded that application of either the Alloy Primer or the Estenia Opaque Primer, both of which contain 10-methacryloyloxydecyl dihydrogen phosphate (MDP), is recommended for bonding the Katana zirconia material with TBB-initiated acrylic resin.

A retrospective survey on long-term survival of posterior zirconia and porcelain-fused-to-metal crowns in private practice

OBJECTIVES This retrospective survey assessed the clinical survival of zirconia-based crowns (PFZ) and conventional porcelain- fused-to-metal (PFM) crowns on posterior teeth in private practice. METHOD AND MATERIALS A print survey of 13 private practitioners was conducted to assess the long-term survival of previously placed full-coverage crowns. The practitioners reported a total of 2,182 premolar (n = 881) and molar (n = 1,301) full-coverage single crowns, 1,102 PFZ and 1,080 PFM, fabricated by one dental laboratory (Cusp, Boston) and followed over 7.4 years. All post-cementation complications (eg, porcelain fractures and chippings) were recorded as failures. In the PFZ group, one veneering porcelain (CZR, Kuraray Noritake) was used in combination with three coping systems (Lava, 3M ESPE; Procera, Nobelbiocare; Katana, Kuraray Noritake). Kaplan-Meier survival analysis was used for statistical analyses. RESULTS The probability of survival of posterior crowns investigated over the period of study (7.4 years) was 99.3% for PFM and 99.2% for PFZ restorations. There was no statistically significant difference (P = .614) between PFZ and PFM groups. In the PFZ group, probability of survival was 97.7% for Lava, 100% for Procera, and 99.5% for Katana. There were no statistically significant differences (P = .34) between the three PFZ systems or the location of the crowns (premolar or molar; P = .454). CONCLUSION PFZ crowns fabricated with CZR and three commercial zirconia coping systems revealed excellent long-term success rates. Survival times and survival probabilities of posterior PFZ crowns did not differ from PFM crowns and were independent of type of coping system and location (molar or premolar teeth).