Shear bond strength between gingival composite resin and glazed gingival porcelain for implant-supported prostheses.

This study determined the shear bond strength (SBS) between an indirect gingival composite resin and glazed gingival porcelain after various surface treatments. A total of 176 porcelain disks with natural glazing were used and assigned to one of four groups: no surface treatment, airborne-particle abrasion, hydrofluoric acid etching, or a combination of airborne-particle abrasion followed by hydrofluoric acid etching. Each group was divided into two subgroups: one subgroup was unprimed, and the other was silanized. An indirect composite resin was then bonded to the porcelain disks. Half of the specimens in each group (n = 11) were exposed to 5000 thermocycles. SBSs were measured, and data were analyzed with the Kruskal-Wallis and Steel-Dwass tests. Among silanized specimens, those treated with the combination of airborne-particle abrasion and hydrofluoric acid etching exhibited the highest bond strengths both before and after thermocycling. However, the SBS values of the silanized and unprimed hydrofluoric acid etched specimens did not differ significantly. Airborne-particle abrasion followed by hydrofluoric acid etching with silane application yielded stronger, more durable bonds between the indirect gingival composite resin and glazed gingival porcelain.

An in vitro evaluation of fracture load of implant-supported zirconia-based prostheses fabricated with different veneer materials.

OBJECTIVES: The purpose of this in vitro study was to evaluate fracture loads of implant-supported zirconia-based prostheses fabricated with different veneer materials (resin-based material and lithium disilicate ceramics). MATERIAL AND METHODS: Forty-four zirconia-based molar prostheses were fabricated on dental implants and divided into four groups (n = 11): zirconia-based prostheses veneered with feldspathic porcelain (ZVF), zirconia-based prostheses bonded with the lithium disilicate glass-ceramic veneer (ZBD), zirconia-based prostheses veneered with indirect composite resin (ZVC), and zirconia-based prostheses bonded with composite materials fabricated from a CAD/CAM resin block (ZBC). The zirconia-based prostheses and abutments were adhesively bonded with a dual-polymerized resin-based luting material. Fracture load was determined using compression load to the prostheses with a universal testing machine. The data were analyzed with one-way analysis of variance (ANOVA) and Tukey's HSD test (α = .05). RESULTS: The mean fracture load was significantly higher in the ZBC group (3.95 kN) than in the ZVC group (3.28 kN). No significant difference in fracture load was found among the ZVF (3.52 kN), ZBD (3.48 kN), and ZVC groups. CONCLUSIONS: The adhesively bonded veneering technique enhances fracture resistance of implant-supported zirconia-based prostheses fabricated with a resin-based material. All implant-supported zirconia-based restorations tested should resist physiologic masticatory forces in the oral environment.

Effect of preparation design on marginal and internal adaptation of translucent zirconia laminate veneers.

This study investigated the effect of preparation design on the marginal and internal adaptation of laminate veneers (LVs) fabricated from translucent zirconia. Thirty-three resin teeth were prepared for LVs of three designs: window preparation (WP); incisal shoulder preparation (ISP); and incisal palatal chamfer preparation (IPP). Marginal adaptation was evaluated by measuring the vertical discrepancy between the LV margin and the finish line at 60 points. The internal adaptation was assessed by measuring the internal space width as the distance between the LV and the tooth at cervical, central, and incisal sites after sectioning. At the incisal, mesial, and distal sites, mean marginal discrepancies were significantly lower in the WP group than in the other two groups; the IPP group had the highest marginal discrepancies. At incisal sites, the median internal space was significantly higher in the IPP group than in the WP and ISP groups and higher in the ISP group than in the WP group. At the incisal site, marginal and internal adaptations were better for the non-overlap translucent zirconia LV design (WP) than for the overlap designs (ISP and IPP). The characteristics of the translucent zirconia LVs used in the present study indicate acceptable clinical performance.

Fracture resistance of implant-supported screw-retained zirconia-based molar restorations.

OBJECTIVES: The objective of this in vitro study was to investigate fracture loads of screw-retained zirconia-based molar restorations (hybrid abutment crown) fabricated with different restorative materials and designs. MATERIAL AND METHODS: Forty-four screw-retained zirconia-based molar restorations were fabricated on dental implants and divided into four groups (n = 11): porcelain-layered zirconia-based restorations (PLZ), indirect composite-layered zirconia-based restorations (ILZ), metal-ceramic restorations (MC), and monolithic zirconia restorations (MONO). The zirconia-based restorations in the PLZ, ILZ, and MONO groups were adhesively bonded on implant abutments with a dual-polymerized resin material. All restorations were tightened on implant bodies with titanium screws and were tested for fracture resistance. The Kruskal-Wallis test and Steel-Dwass test were used to evaluate differences in fracture loads (α = 0.05). RESULTS: As compared with the other groups, the MONO specimens had a significantly higher mean fracture resistance (7.54 kN); no significant differences were found among the PLZ (1.96 kN), ILZ (1.80 kN), and MC (1.45 kN) groups (P > 0.05). For the PLZ, ILZ, and MC groups, all specimens fractured within the layering materials. In contrast, the fracture mode for the MONO group was complete fracture of the restorations. CONCLUSIONS: All restorations withstood the masticatory forces. Fracture loads were significantly higher for screw-retained implant-supported monolithic zirconia restorations than for screw-retained bilayered restorations. For the screw-retained bilayered zirconia-based restorations, the fracture resistance of ILZ restorations was comparable to that of PLZ restorations and MC restorations.

Effects of framework design and layering material on fracture strength of implant-supported zirconia-based molar crowns.

OBJECTIVES: To evaluate the effects of framework design and layering material on the fracture strength of implant-supported zirconia-based molar crowns. MATERIAL AND METHODS: Sixty-six titanium abutments (GingiHue Post) were tightened onto dental implants (Implant Lab Analog). These abutment-implant complexes were randomly divided into three groups (n = 22) according to the design of the zirconia framework (Katana), namely, uniform-thickness (UNI), anatomic (ANA), and supported anatomic (SUP) designs. The specimens in each design group were further divided into two subgroups (n = 11): zirconia-based all-ceramic restorations (ZAC group) and zirconia-based restorations with an indirect composite material (Estenia C&B) layered onto the zirconia framework (ZIC group). All crowns were cemented on implant abutments, after which the specimens were tested for fracture resistance. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test with the Bonferroni correction (α = 0.05). RESULTS: The following mean fracture strength values (kN) were obtained in UNI design, ANA design, and SUP design, respectively: Group ZAC, 3.78, 6.01, 6.50 and Group ZIC, 3.15, 5.65, 5.83. In both the ZAC and ZIC groups, fracture strength was significantly lower for the UNI design than the other two framework designs (P = 0.001). Fracture strength did not significantly differ (P > 0.420) between identical framework designs in the ZAC and ZIC groups. CONCLUSIONS: A framework design with standardized layer thickness and adequate support of veneer by zirconia frameworks, as in the ANA and SUP designs, increases fracture resistance in implant-supported zirconia-based restorations under conditions of chewing attrition. Indirect composite material and porcelain perform similarly as layering materials on zirconia frameworks.

Long-term Bond Strength between Layering Indirect Composite Material and Zirconia Coated with Silicabased Ceramics.

PURPOSE: This study evaluated the long-term shear bond strength between an indirect composite material and a zirconia framework coated with silica-based ceramics, taking the effect of different primers into account. MATERIALS AND METHODS: A total of 165 airborne-particle abraded zirconia disks were subjected to one of three pretreatments: no pretreatment (ZR-AB), airborne-particle abrasion of zirconia coated with feldspathic porcelain (ZR-PO-AB), and 9.5% hydrofluoric acid etching of zirconia coated with feldspathic porcelain (ZR-PO-HF). An indirect composite material (Estenia C&B) was then bonded to the zirconia disks after they were treated with one of the following primers: Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid B (PLB), or no priming (CON, control group). Shear bond strength was tested after 100,000 thermocycles, and the data were analyzed using the Steel-Dwass U-test (α = 0.05). RESULTS: For ZR-PO-AB and ZR-PO-HF specimens, bond strength was highest in the CPB+Activator group (25.8 MPa and 22.4 MPa, respectively). Bond strengths were significantly lower for ZR-AB specimens in the CON and PLB groups and for ZR-PO-AB specimens in the CON, CPB, and EOP groups. CONCLUSION: Combined application of a hydrophobic phosphate monomer (MDP) and silane coupling agent enhanced the long-term bond strength of indirect composite material to a zirconia coated with silica-based ceramics.

Fracture resistance of single-tooth implant-supported zirconia-based indirect composite-layered molar restorations.

OBJECTIVES: This study evaluated the fracture resistance of single-tooth implant-supported zirconia-based indirect composite-layered molar restorations. MATERIAL AND METHODS: Forty-four titanium abutments (GingiHue Post) were placed on dental implants (Osseotite Implant). Standardized single-tooth cement-retained implant-supported mandibular molar restorations were fabricated for each of four test groups (n = 11) as follows: porcelain-fused-to-metal crowns (PFM), zirconia-based all-ceramic crowns (ZAC), zirconia-based indirect composite-layered crowns primed with Estenia Opaque Primer for zirconia frameworks (ZIC-E), and zirconia-based indirect composite-layered crowns (ZIC). The crowns were luted with a glass-ionomer cement (Ketac Cem Easymix). Fracture resistance (N) was determined by force application of a perpendicular load to the crowns with a universal testing machine. One-way analysis of variance (ANOVA) and the Tukey's HSD test were used to assess differences in fracture resistance values (α = 0.05). RESULTS: Mean fracture resistances (SD) were 3.09 (0.22) kN, 3.11 (0.34) kN, 2.84 (0.21) kN, and 2.50 (0.36) kN for the PFM, ZAC, ZIC-E, and ZIC groups, respectively. Fracture resistance in the ZIC specimens was significantly lower (P < 0.044) than that in the other groups, which did not significantly differ. CONCLUSIONS: The fracture resistance of single-tooth implant-supported zirconia-based indirect composite-layered molar crowns primed with Estenia Opaque Primer for zirconia frameworks (ZIC-E) is comparable to that of porcelain-fused-to-metal (PFM) and zirconia-based all-ceramic (ZAC) restorations. Application of Estenia Opaque Primer to zirconia ceramic framework provides superior fracture resistance in implant-supported zirconia-based indirect composite-layered molar crowns.

Influence of different convergence angles of abutment teeth and cement spaces on internal adaptation of anterior CAD-CAM fixed dental prostheses.

PURPOSE: The aim of this study was to investigate the influence of different convergence angles of abutment teeth and different cement spaces on internal adaptation of anterior fixed dental prostheses (FDPs) fabricated with a computer-aided design-computer-aided manufacturing (CAD-CAM) system. METHODS: Composite resin FDPs for 99 standardized maxillary central incisors were fabricated according to nine parameters: three total convergence angles (4 [DG4], 12 [DG12], and 20 degrees [DG20]) and three cement space settings (10 [CS10], 50 [CS50], and 90 µm [CS90]). Internal space values were measured with a cement space replica technique. The Kruskal-Wallis and Steel-Dwass tests were used to evaluate differences in the total convergence angles and luting agent spaces, respectively (α = 0.05). RESULTS: For all three cement spaces tested, the median marginal gap values between abutment teeth and FDPs decreased significantly as the total convergence angle increased (P < 0.05). For the CS10 and CS50 groups, the internal space values at the axial area increased significantly as the total convergence angles increased (P < 0.05). CONCLUSION: Total convergence angles of the abutment teeth and cement spaces affected the marginal and internal adaptation of anterior FDPs fabricated with a CAD-CAM system.

Influence of attaching mechanical retentive devices onto frameworks on fracture resistance of implant-supported zirconia crowns.

This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto zirconia frameworks with mechanical retentive devices. Three different zirconia frameworks were assessed: attaching mechanical retentive devices on glaze and opaque porcelain materials (GL and OP groups, respectively), and no attaching mechanical retentive devices (ND group). The frameworks were layered using feldspathic porcelain (FP veneer) and indirect composite resin (IC veneer). Fracture load of the specimens was measured. In FP veneer, the GL group recorded the highest fracture load. In the IC veneer, the GL and OP groups had significantly higher fracture load than the ND group. The fracture resistance of IZCs can be enhanced by applying glaze material before attaching mechanical retentive devices for porcelain layering. The mechanical retentive devices effectively yielded mechanical interlocking between the zirconia frameworks and the IC veneer in GL and OP groups.

Clinical performance of laminate veneers: A review of the literature.

PURPOSE: This narrative review aimed to survey the clinical outcomes of laminate veneers (LVs), including their survival and success rates. STUDY SELECTION: An electronic search of MEDLINE/PubMed, Web of Science, Cochrane Library, and Google Scholar from 2000 to April 2023 was conducted using the keywords "laminate" OR "veneer" OR "porcelain" OR "feldspathic" OR "lithium disilicate" OR "composite resin" OR "zirconia" OR "survival" OR "success." Case reports, case series, reviews, abstracts, in vitro studies, and observational studies were excluded. Five researchers independently evaluated the titles and abstracts of all identified studies. RESULTS: A total of 55 studies were identified. None of the studies met the criteria for zirconia LVs. According to the studies in this review, LVs fabricated with feldspathic porcelain, leucite-reinforced glass ceramics (LRG), and lithium disilicate ceramics (LDS) exhibited satisfactory survival and success rates. Furthermore, hydrofluoric acid etching followed by silane priming of the surface of ceramic LVs is necessary for improved clinical outcomes. The extent of dentin exposure significantly decreases the success rate of ceramic LVs. An appropriate adhesive luting process is required to achieve the long-term success of ceramic LVs. Dentin exposure should be minimized or sealed during tooth preparation to achieve a reliable and durable bond between LVs and abutment teeth. CONCLUSIONS: Based on this narrative review of the literature, the use of silica-based ceramic feldspathic porcelain, LRG, and LDS is recommended for LVs.

The effect of different surface treatments on the bond strength of a gingiva-colored indirect composite veneering material to three implant framework materials.

OBJECTIVES: To evaluate and compare the shear-bond strength of a gingiva-colored indirect composite material to three different implant framework materials (zirconia ceramics, gold alloy, and titanium), and to investigate the effect of surface pretreatment by air-particle abrasion and four priming agents. MATERIAL AND METHODS: A gingiva-colored indirect composite (Ceramage) was bonded to three framework materials (n = 80): commercially pure titanium (CP- Ti ), ADA (American Dental Association)-type 4 casting gold alloy (Type IV), and zirconia ceramics (Zirconia) with or without airborne-particle abrasion. Before bonding, the surface of the specimens was treated using no (control) or one of four priming agents: Alloy Primer (ALP), Estenia Opaque Primer (EOP), Metal Link Primer (MLP), and V-Primer (VPR). Shear-bond strength was determined after 24-h wet storage. Data were analyzed using Steel-Dwass for multiple comparisons, and Mann-Whitney U-test (P = 0.05). RESULTS: For both CP- Ti and Zirconia substrates, three groups, ALP, EOP, and MLP, showed significantly higher bond strengths (P < 0.05) than the other groups with or without airborne-particle abrasion. For Type IV substrates, significantly higher bond strengths were obtained in ALP and MLP groups (P < 0.01) compared with the other groups with airborne-particle abrasion. CONCLUSIONS: Application of priming agents containing specific phosphoric ester groups significantly enhances the bond strength of a gingiva-colored composite material to commercially pure titanium and zirconia frameworks. Combined use of a thione monomer with a phosphoric monomer enhances the bond strengths to airborne-particle abraded type IV gold alloy.

Post-thermocycling shear bond strength of a gingiva-colored indirect composite layering material to three implant framework materials.

OBJECTIVE: To evaluate shear bond strength of a gingiva-colored indirect composite to three implant framework materials, before and after thermocycling, and verify the effect of surface pre-treatment for each framework. MATERIALS AND METHODS: Commercially pure titanium (CP-Ti), American Dental Association (ADA) type 4 casting gold alloy (Type IV) and zirconia ceramics (Zirconia) were assessed. For each substrate, 96 disks were divided into six groups and primed with one of the following primers: Alloy Primer (ALP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Activator), Estenia Opaque Primer (EOP), Metal Link (MLP) and V-Primer (VPR). The specimens were then bonded to a gingiva-colored indirect composite (Ceramage Concentrate GUM-D). Shear bond strengths were measured at 0 and 20 000 thermocycles and data were analyzed with the Steel-Dwass test and Mann-Whitney U-test. RESULTS: Shear bond strengths were significantly lower after thermocycling, with the exception of Type IV specimens primed with CPB (p = 0.092) or MLP (p = 0.112). For CP-Ti and Zirconia specimens, priming with CPB or CPB+Activator produced significantly higher bond strengths at 0 and 20 000 thermocycles, as compared with the other groups. For Type IV specimens, priming with ALP or MLP produced higher bond strengths at 0 and 20 000 thermocycles. CONCLUSIONS: Shear bond strength of a gingiva-colored indirect composite to CP-Ti, gold alloy and zirconia ceramics was generally lower after thermocycling. Application of a hydrophobic phosphate monomer and polymerization initiator was effective in maintaining bond strength of CP-Ti and zirconia ceramics. Combined use of a thione monomer and phosphoric monomer enhanced the durable bond strength of gold alloy.

Durability of bond between an indirect composite veneering material and zirconium dioxide ceramics.

OBJECTIVE: The purpose of the present study was to evaluate the durability of bond strength between an indirect composite material and zirconia ceramics after thermocycling (100 000 cycles) and to assess the effect of various priming agents for zirconia surface treatments. MATERIALS AND METHODS: A CAD/CAM system (Katana, Noritake Dental Supply) was used to fabricate 96 zirconia disks as a bonding substrate. The specimens were randomly divided into six groups (n = 16) and treated with one of the following acidic priming agents: Alloy Primer (ALP, Kuraray), Clearfil Ceramic Primer (CCP, Kuraray), Clearfil Photo Bond (CPB, Kuraray), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator, Kuraray), Estenia Opaque Primer (EOP, Kuraray) and Porcelain Liner M Liquid A (PLA, Sun Medical). The specimens were bonded with an indirect composite material (Estenia C&B Dentin, Kuraray). Shear bond strengths were tested before and after 100 000 thermocycles and the data were analyzed by using the Steel-Dwass test and Mann-Whitney U-test. RESULTS: After 100 000 thermocycles, the PLA group showed the lowest bond strength (p = 0.010), whereas the CPB + Activator (23.9 MPa; p < 0.014) and CPB (22.7 MPa; p < 0.028) groups had significantly higher bond strengths than the other groups. The Mann-Whitney U-test revealed that bond strengths did not significantly decrease after thermocycling, except for specimens in the PLA (p = 0.038) and CCP (p = 0.028) groups. CONCLUSIONS: Application of a combination of hydrophobic phosphate monomer (MDP) and initiator results in a durable long-term bond between Katana zirconia and Estenia C&B composite material.

Influence of an internal firing of feldspathic porcelain before or after sintering on adaptation of high-translucent zirconia laminate veneers.

The aim of the present study was to evaluate the influence of two different internal surface treatments, namely, the firing of feldspathic porcelain before or after zirconia sintering, on the marginal and internal adaptation of laminate veneers (LVs) made of high-translucent zirconia. A total of 33 zirconia LVs were fabricated using a CAD/CAM system and divided into three groups based on the internal surface treatment method: the pre-firing (PRE) group involved firing feldspathic porcelain before zirconia sintering, the post-firing (POS) group involved firing feldspathic porcelain after zirconia sintering, and the no treatment (NT) group involved no application of feldspathic porcelain. The adaptation of the LVs was measured using a silicone replica technique. Data were analyzed using the Kruskal-Wallis and Steel-Dwass tests (α = .05). The POS group showed significantly higher marginal discrepancy values than the PRE group across all sites. The internal space values of the PRE groups were significantly lower than those of the NT group at all sites. The internal firing of feldspathic porcelain before zirconia sintering resulted in better marginal adaptation of the high-translucent zirconia LVs than the internal firing of feldspathic porcelain after zirconia sintering. The internal firing of feldspathic porcelain before zirconia sintering can achieve uniform internal adaptation of high-translucent zirconia LVs.

Fracture strength of implant-supported hybrid abutment crowns in premolar region fabricated using different restorative CAD/CAM materials.

The present study investigated the fracture strength of hybrid abutment crowns (HACs) in the premolar region that were fabricated with different restorative computer-aided design/computer-aided manufacturing (CAD/CAM) materials. The abutment-implant structures were randomly assigned into four groups (n=11 per group): bi-layered zirconia restorations (BL), translucent zirconia (4Y-PSZ) restorations (TZ), lithium disilicate ceramic restorations (LD), and dispersed nanoparticle-filled composite resin restorations (CM). All restorations were adhesively bonded to the titanium abutments. After the restoration-abutment complex was tightened onto the implant, the fracture strength was measured. The TZ (2.06 kN) and LD (1.87 kN) groups had significantly higher median fracture strengths than the BL (1.12 kN) and CM (1.10 kN) groups. In terms of fracture resistance, the 4Y-PSZ and lithium disilicate ceramic monolithic restorations would be superior to bi-layered 3Y-TZP and composite resin monolithic restorations for HACs in the premolar region.

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.

Shear bond strength between an indirect composite layering material and feldspathic porcelain-coated zirconia ceramics.

OBJECTIVES: This study aims to evaluate the effect of both feldspathic porcelain coating of zirconia frameworks and priming agents on shear bond strength between an indirect composite material and zirconia frameworks. MATERIALS AND METHODS: A total of 462 airborne-particle-abraded zirconia disks were divided into three groups: untreated disks (ZR-AB), airborne-particle-abraded zirconia disks coated with feldspathic porcelain, (ZR-PO-AB), and hydrofluoric acid-etched zirconia disks coated with feldspathic porcelain (ZR-PO-HF). Indirect composite (Estenia C&B) was bonded to zirconia specimens with no (CON) or one of four priming agents--Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + activator), Estenia Opaque primer, or Porcelain Liner M Liquid B (PLB)--with or without an opaque material (Estenia C&B Opaque). All specimens were tested for shear bond strength before and after 20,000 thermocycles. The Steel-Dwass test and Mann-Whitney U test were used to compare shear bond strength. RESULTS: In ZR-AB specimens, the initial bond strength of the CPB and CPB + Activator groups was significantly higher as compared with the other three groups (P < 0.05), whereas the PLB and CPB + Activator groups had the highest pre- and post-thermocycling bond strengths in ZR-PO-AB and ZR-PO-HF specimens. Among CON disks without opaque material, bond strength was significantly lower in ZR-AB specimens than in ZR-PO-AB and ZR-PO-HF specimens (P < 0.05). CONCLUSION: Feldspathic porcelain coating of a Katana zirconia framework enhanced the bond strength of Estenia C&B indirect composite to zirconia independent of surface treatment. The use of a silane coupling agent and opaque material yields durable bond strength between the indirect composite and feldspathic-porcelain-coated zirconia. CLINICAL RELEVANCE: The results of the present study suggest that feldspathic porcelain coating of zirconia frameworks is an effective method to obtain clinically acceptable bond strengths of a layering indirect composite material to a zirconia framework.

Effect of firing procedures and layering thickness of porcelain on internal adaptation of zirconia cantilever resin-bonded fixed dental prostheses.

PURPOSE: This study evaluated the influence of firing procedures and layering thickness of porcelain on internal adaptation of maxillary anterior cantilever zirconia resin-bonded fixed dental prostheses (RBFDPs). METHODS: The maxillary right central incisor on a model was prepared for a single-retainer zirconia RBFDP. A total of 36 frameworks of cantilever zirconia RBFDPs were classified into three groups (CB0.5, CB1.0, and CB2.0 groups) based on the thickness of the cut-back on the facial surface (0.5 mm, 1.0 mm, and 2.0 mm, respectively). Feldspathic porcelain was layered onto the facial surface of the zirconia RBFDP frameworks. Internal space widths between the abutment tooth and the framework were measured before and after porcelain firing by a replica technique. The internal space values before and after porcelain firings were compared using the paired t-test within the same group (α = 0.05). Differences in internal space values (distortion) between before and after porcelain firing were compared using one-way analysis of variance and Tukey multiple comparison tests. RESULTS: For all framework designs, internal space values after porcelain firing were significantly higher than those before firing. Among all groups, the CB0.5 group showed the lowest internal distortion values for the whole measured area. The CB2.0 group showed higher distortion values than the CB1.0 group. CONCLUSION: Porcelain firing procedures negatively impacted the internal space in cantilever zirconia RBFDPs. In addition, the increased volume of layering porcelain had a negative effect on the internal distortion of maxillary anterior cantilever zirconia RBFDPs.

Bond strength between a veneering composite resin and zirconia frameworks with attached mechanical retentive devices.

The effects of mechanical retentive devices and various surface treatments on the shear bond strength between a veneering composite resin and zirconia was investigated. Zirconia disks were classified into three surface-treatment groups: airborne-particle abrasion, overglazing, and overglazing with white alumina particles of three different grain sizes (50, 70, and 105 µm) attached onto zirconia disks (ZR-50, ZR-70, and ZR-105, respectively). They were further divided into four groups (n=44): unprimed, Clearfil Porcelain Bond Activator (CA), Clearfil Photo Bond (CB), and CA+CB. An indirect composite resin was bonded to zirconia specimens. Shear bond strengths were measured. For the ZR-70 and ZR-105 groups, the CB and CA+CB specimens exhibited higher bond strengths than the other two specimens after thermocycling. The ZR-70 and ZR-105 groups achieved micromechanical interlocking, and priming with a phosphate monomer (MDP) yielded stable bond strengths between the composite resin and zirconia with alumina particles attached as retentive devices.

Influence of roughening procedures and priming agents on shear bond strength of CAD/CAM materials to zirconia frameworks.

This study investigated the influence of roughening procedures and application of primers on shear bond strengths of CAD/CAM composite resin material or ceramic material to zirconia frameworks. A CAD/CAM composite resin block (Katana Avencia Block; AVE) and lithium disilicate glass-ceramic block (IPS e.max CAD; IEC) were used as veneer materials. The veneers were divided into three surface treatment groups; HF, hydrofluoric acid etching; AB, airborne-particle abrasion; and CON, no surface treatment. Each veneer was primed with four agents: Clearfil Porcelain Bond Activator (ACT), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Porcelain Bond Activator (CPB+ACT), and no priming (UP). The zirconia frameworks and AVE or IEC veneers were resin-bonded. In the AVE specimen, AB treatment showed significantly higher shear bond strength than the other treatments at 0 and 20,000 thermocycles, except for UP and CPB+ACT groups at 20,000 thermocycles. Airborne-particle abrasion is necessary for resin bonding to Avencia blocks.