Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces.

With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface conditioning methods: fine diamond bur, sandblasting, 5% hydrofluoric acid, and silica coating for bonding metal brackets to ceramic surfaces of feldspathic porcelain. Sandblasting and hydrofluoric acid were further tested after silane application. A total of 120 ceramic disc samples were produced, and 50 were used for surface roughness measurements. The glazed ceramic surfaces were used as controls. Metal brackets were bonded to the ceramic substrates with a self-curing composite. The samples were stored in 0.9% NaCl solution for 24 hours and then thermocycled (5000 times, 5 degrees C to 55 degrees C, 30 seconds). Shear bond tests were performed with a universal testing device, and the results were statistically analyzed. Chemical surface conditioning with either hydrofluoric acid (4.3 microm) or silicatization (4.4 microm) resulted in significantly lower surface roughness than mechanical conditioning (9.3 microm, diamond bur; 9.7 microm, sandblasting) (P <.001). The surface roughness values reflect the mean peak-and-valley distances. The bond strengths of the brackets bonded to the ceramic surfaces treated by hydrofluoric acid with and without silane (12.2 and 14.7 MPa, respectively), silicatization (14.9 MPa), and sandblasting with silane (15.8 MPa) were significantly higher (P <.001) than those treated by mechanical roughening with fine diamond burs (1.6 MPa) or sandblasting (2.8 MPa). The highest bond strength values were obtained with sandblasting and silicatization with silane or hydrofluoric acid without silane; these fulfilled the required threshold. The use of silane after hydrofluoric acid etching did not increase the bond strength. Diamond roughening and sandblasting showed the highest surface roughness; they can damage the ceramic surface. Acid etching gave acceptable results for clinical use, but the health risks should be considered. The silicatization technique has the potential to replace the other methods; yet cohesive failures were observed in the ceramic during removal of the brackets.     

Bonding polycarbonate brackets to ceramic: effects of substrate treatment on bond strength.

This study evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. Six disc-shaped ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were randomly assigned to 1 of the following treatment conditions of the ceramic surface: (1) orthophosphoric acid + primer + bonding agent, (2) hydrofluoric acid gel + primer + bonding agent, (3) tribochemical silica coating (silicon dioxide, 30microm) + silane, (4) airborne particle abrasion (aluminum trioxide, 30microm) + silane, and (5) airborne particle abrasion (aluminum trioxide, 30microm) + silane + bonding agent. Brackets were bonded to the conditioned ceramic specimens with a light-polymerized resin composite. All specimens were stored in water for 1 week at 37 degrees C and then thermocycled (1000 cycles, 5 degrees C to 55 degrees C, 30 seconds). The shear bond strength values were measured on a universal testing machine at a crosshead speed of 1 mm/min. Brackets treated with silica coating with silanization had significantly greater bond strength values (13.6 MPa, P =.01) than brackets treated with orthophosphoric acid (8.5 MPa). There was no significant difference (P =.97) between the bond strengths obtained after airborne abrasion with aluminium trioxide particles followed by silanization (12 MPa) and hydrofluoric acid application (11.2 MPa) (ANOVA and Tukey test). Although brackets conditioned with orthophosphoric acid exhibited only adhesive failures of the luting cement from the ceramic surface, other conditioning methods showed mixed types of failures. Airborne particle abrasion with aluminium trioxide or silica coating followed by silanization gave the most favorable bond strengths. The types of failures observed after debonding indicated that the critical parameter was the strength of the adhesive joint of the luting cement to both the bracket and the ceramic.     

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.     

Influence of surface conditions and silane agent on the bond of resin to IPS Empress 2 ceramic

PURPOSE: The aim of this study was to evaluate the effect of different ceramic surface treatments on the tensile bond strength between IPS Empress 2 ceramic framework and Rely X adhesive resin cement, with or without the application of a silane coupling agent. MATERIALS AND METHODS: One hundred twenty disks were made, embedded in resin, and randomly divided into six groups: group 1 = sandblasting (100 microm), no silanation; group 2 = sandblasting (100 microm), silane treatment; group 3 = sandblasting (50 microm), no silanation; group 4 = sandblasting (50 microm), silane treatment; group 5 = hydrofluoric acid etching, no silanation; and group 6 = hydrofluoric acid etching, silane treatment. The disks were bonded into pairs with adhesive resin cement. All samples were stored in distilled water at 37 degrees C for 24 hours and then thermocycled. The samples were submitted to tensile testing. RESULTS: The use of silane improved the bond strength in relation to the groups in which silane was not applied (P < .05). The most effective surface treatment was etching with 10% hydrofluoric acid, both with (25.6 MPa) and without silane application (16.4 MPa); these values showed a statistically significant difference compared to sandblasting with 50- and 100-microm Al2O3. Sandblasting with 50-microm Al2O3, with (11.8 MPa) and without silane (5.4 MPa), demonstrated significantly higher tensile bond strength than sandblasting with 100-microm Al2O3, with (8.3 MPa) and without silane (3.8 MPa). CONCLUSION: Combined application of 10% hydrofluoric acid and silane enhanced the bond strength between the IPS Empress 2 ceramic framework and resin agent.     

Porcelain surface treatment by laser for bracket-porcelain bonding.

INTRODUCTION: The purposes of this study were to investigate the effect of laser irradiation on the adhesion of brackets bonded to feldspathic porcelain and to compare it with brackets bonded with conventional techniques. METHODS: One hundred porcelain-fused-to-metal specimens were divided into 10 groups of 10. The treatment groups were sandblasted (SB), sandblasted with silane (SB+S), orthophosphoric acid (OFA), orthophosphoric acid with silane (OFA+S), hydrofluoric acid (HFA), hydrofluoric acid with silane (HFA+S), laser etched (L), laser etched with silane (L+S), glazed (Control 1/C1), and deglazed (Control 2/C2). Five other specimens were irradiated by 2-, 3-, 5-, 10-, and 15-watt superpulse carbon dioxide (CO2) laser for 20 seconds and examined by scanning electron microscopy. Metal brackets were bonded with a self-cure composite material and the specimens were stored in water at 37 degrees C for 24 hours and then thermocycled in water baths between 5 degrees C and 55 degrees C 500 times. Bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed. Bond failure modes were observed under stereomicroscope. For the statistical analysis, 1-way ANOVA and Tamhane post hoc test were used. RESULTS: Statistical analysis showed significant differences between the groups at the .05 level. The HFA+S group yielded the highest mean strength (15.07 +/- 1.44). This was followed by SB+S (13.81 +/- 2.00), HFA (10.78 +/- 0.62), OFA+S (10.73 +/- 1.12), L+S (8.25 +/- 0.90), L (6.26 +/- 0.58), C2 (2.45 +/- 0.54), OFA (2.36 +/- 0.41), SB (2.04 +/- 0.41), and C1 (1.64 +/- 0.33). The bond failure modes of HFA and silane groups, except L+S, were cohesive in porcelain. Control groups and other test groups showed adhesive failure. Only irradiation by 2 watts for 20 seconds provided a porous surface texture without cracks. CONCLUSIONS: Two-watt/20 second superpulse CO2 laser irradiation might be an alternative conditioning method for pretreating ceramic surfaces. Increased bond strength can be achieved by silanation after CO2 laser irradiation.     

Shear bond strengths of two resin-modified glass ionomer cements to porcelain.

Shear bond strength of a composite resin adhesive (Concise) and two resin-modified glass ionomer cements (Fuji Ortho LC and Geristore) bonded to porcelain surface was tested. Orthodontic brackets were bonded to 120 porcelain disks (Finesse) etched with 9% HF. Samples were divided into six groups: (1) Concise, (2) Concise/silane, (3) Geristore, (4) Geristore/silane, (5) Fuji, (6) Fuji/silane. No statistical difference in mean shear bond strength was found between silanated Concise (15.8 MPa), Geristore (19.4 MPa), and Fuji (18.5 MPa) groups, which were significantly higher than nonsilanated groups. Porcelain fracture was observed in all silanated groups and nonsilanated Geristore group. We conclude that (1) silane increases bond strength to porcelain significantly for composite resin and resin-modified glass ionomer cement, (2) Concise, Geristore, and Fuji Ortho LC provide comparable shear bond strength to porcelain.     

Shear bond strength of rebonded mechanically retentive ceramic brackets.

The purpose of this study was to evaluate the bond strength of rebonded mechanically retentive ceramic brackets. Twenty new and 100 sandblasted rebonded ceramic brackets (Clarity, 3M Unitek, Monrovia, Calif) were bonded to 120 extracted human premolars with composite resin and divided into 6 equal groups according to how the bracket bases were treated: (1) new brackets, (2) rebonded/sandblasted, (3) rebonded/sandblasted/sealant, (4) rebonded/sandblasted/hydrofluoric acid (HF), (5) rebonded/sandblasted/HF/sealant on bracket base, and (6) rebonded/sandblasted/silane. Shear bond strength of each sample was tested with a testing machine. Results showed that the new brackets group had the highest mean strength (15.66 +/- 7.05 megapascals [MPa]), followed by the rebonded/sandblasted/sealant group (7.65 +/- 5.62 MPa), the rebonded/sandblasted/silane group (5.94 +/- 5.33 MPa), the rebonded/sandblasted group (2.97 +/- 2.29 MPa), the rebonded/sandblasted/HF group (1.22 +/- 1.66 MPa), and the rebonded/sandblasted/HF/sealant group (0.82 +/- 1.16 MPa). Statistical analysis showed that only the rebonded/sandblasted/sealant group was comparable with the new brackets group in bond strength (P >.05). It was concluded that in the process of rebonding mechanically retentive ceramic brackets, (1) new brackets have the highest mean bond strength when compared with rebonded brackets, (2) the bond strength of sandblasted rebonded brackets with sealant is not significantly different from new brackets, (3) silane does not increase bond strength of rebonded brackets significantly, and (4) HF treatment on sandblasted rebonded brackets significantly decreases bond strength.     

Comparison of two bond strength testing methodologies for bilayered all-ceramics.

OBJECTIVES: This study compared the shear bond strength (SBS) and microtensile (MTBS) testing methodologies for core and veneering ceramics in four types of all-ceramic systems. METHODS: Four different ceramic veneer/core combinations, three of which were feldspathic and the other a fluor-apatite to their respectively corresponding cores, namely leucite-reinforced ceramic ((IPS)Empress, Ivoclar), low leucite-reinforced ceramic (Finesse, Ceramco), glass-infiltrated alumina (In-Ceram Alumina, Vita) and lithium disilicate ((IPS)Empress 2, Ivoclar) were used for SBS and MTBS tests. Ceramic cores (N=40, n=10/group for SBS test method, N=5 blocks/group for MTBS test method) were fabricated according to the manufacturers' instructions (for SBS: thickness, 3mm; diameter, 5mm and for MTBS: 10 mm x 10 mm x 2 mm) and ultrasonically cleaned. The veneering ceramics (thickness: 2mm) were vibrated and condensed in stainless steel moulds and fired onto the core ceramic materials. After trying the specimens in the mould for minor adjustments, they were again ultrasonically cleaned and embedded in PMMA. The specimens were stored in distilled water at 37 degrees C for 1 week and bond strength tests were performed in universal testing machines (cross-head speed: 1mm/min). The bond strengths (MPa+/-S.D.) and modes of failures were recorded. RESULTS: Significant difference between the two test methods and all-ceramic types were observed (P<0.05) (2-way ANOVA, Tukey's test and Bonferroni). The mean SBS values for veneering ceramic to lithium disilicate was significantly higher (41+/-8 MPa) than those to low leucite (28+/-4 MPa), glass-infiltrated (26+/-4 MPa) and leucite-reinforced (23+/-3 MPa) ceramics, while the mean MTBS for low leucite ceramic was significantly higher (15+/-2 MPa) than those of leucite (12+/-2 MPa), glass-infiltrated (9+/-1 MPa) and lithium disilicate ceramic (9+/-1 MPa) (ANOVA, P<0.05). SIGNIFICANCE: Both the testing methodology and the differences in chemical compositions of the core and veneering ceramics influenced the bond strength between the core and veneering ceramic in bilayered all-ceramic systems.     

Effects of surface conditioning on bond strength of metal brackets to all-ceramic surfaces

The aim of this study was to determine the effectiveness of bonding brackets to ceramic restorations. Sixty feldspathic and 60 lithium disilicate ceramic specimens were randomly divided into six groups. Shear bond strength (SBS) and bond failure types were examined with six surface-conditioning methods: silane application to glazed surface, air particle abrasion (APA) with 25- and 50-microm aluminium trioxide (Al(2)O(3)), etching with 9.6 per cent hydrofluoric acid (HFA), and roughening with 40- and 63-microm diamond burs. Silane was applied to all roughened surfaces. Metal brackets were bonded with light cure composite, then stored in distilled water for 1 week and thermocycled (x500 at 5-55 degrees C for 30 seconds). The ceramic surfaces were examined with a stereomicroscope at a magnification of x10 to determine the amount of composite resin remaining using the adhesive remnant index. The lowest SBS values were obtained with HFA for feldspathic (5.39 MPa) and lithium disilicate (11.11 MPa) ceramics; these values were significantly different from those of the other groups. The highest SBS values were found with 63-microm diamond burs for feldspathic (26.38 MPa) and lithium disilicate (28.20 MPa) ceramics, and were not significantly different from 40-microm diamond burs for feldspathic and lithium disilicate ceramics (26.04 and 24.26 MPa, respectively). Roughening with 25- and 50-microm Al(2)O(3) particles showed modest SBS for lithium disilicate (22.60 and 26.15 MPa, respectively) and for feldspathic ceramics (17.90 and 14.66 MPa, respectively). Adhesive failures between the ceramic and composite resin were noted in all groups. Damage to the porcelain surfaces was not observed. The SBS values were above the optimal range, except for feldspathic ceramic treated with HFA and silane. With all surface-conditioning methods, lithium disilicate ceramic displayed higher SBS than feldspathic ceramic.     

Effects of silica coating and silane surface conditioning on the bond strength of metal and ceramic brackets to enamel

OBJECTIVE: To evaluate the effect of tribochemical silica coating and silane surface conditioning on the bond strength of metal and ceramic brackets bonded to enamel surfaces with light-cured composite resin. MATERIALS AND METHODS: Twenty metal and 20 ceramic brackets were divided into four groups (n = 10 for each group). The specimens were randomly assigned to one of the following treatment conditions of the metal and ceramic brackets' surface: (1) tribochemical silica coating combined with silane and (2) no treatment. Brackets were bonded to the enamel surface on the labial and lingual sides of human maxillary premolars (20 total) with a light-polymerized resin composite. All specimens were stored in water for 1 week at 37 degrees C and then thermocycled (5000 cycles, 5 degrees C to 55 degrees C, 30 seconds). The shear bond strength values were measured on a universal testing machine. Student's t-test was used to compare the data (alpha = 0.05). The types of failures were observed using a stereomicroscope. RESULTS: Metal and ceramic brackets treated with silica coating with silanization had significantly greater bond strength values (metal brackets: 14.2 +/- 1.7 MPa, P < .01; ceramic brackets: 25.9 +/- 4.4 MPa, P < .0001) than the control groups (metal brackets: 11.9 +/- 1.3 MPa; ceramic brackets: 15.6 +/- 4.2 MPa). Treated specimens of metal and ceramic exhibited cohesive failures in resin and adhesive failures at the enamel-adhesive interface, whereas control specimens showed mixed types of failures. CONCLUSIONS: Silica coating with aluminum trioxide particles coated with silica followed by silanization gave higher bond strengths in both metal and ceramic brackets than in the control group.     

Adhesive bonding of a lithium disilicate ceramic material with resin-based luting agents

This study evaluates the bonding characteristics of a lithium disilicate-based ceramic material (IPS Empress 2). Two sizes of disk specimens of the material were made, and three groups of disk pairs were separately surface-prepared using three techniques; etching with phosphoric acid, etching with hydrofluoric acid, and air-abrasion with alumina. Each group was further divided into four sub-groups; group (i) was bonded with the Variolink II composite, (ii) was treated with the Monobond-S silane primer and bonded with the Variolink II composite, (iii) was bonded with the Super-Bond acrylic adhesive and (iv) was treated with the Porcelain Liner M silane primer and bonded with the Super-Bond acrylic adhesive. Shear bond strengths were determined before and after 100 000 thermocycles. Bond strength varied from 10.6 to 71.5 MPa before thermocycling, whereas post-thermocycling bond strength ranged from 0 to 61.2 MPa. Among the three surface preparations, hydrofluoric acid etching (HF) was most effective in enhancing bond strength of both luting materials, especially for unsilanized specimens. Application of the silane primer elevated bond strength of both luting agents regardless of surface preparation method. It can be concluded, for both luting agents, that durable bond to the Empress 2 ceramic material can be achieved through the combined application of HF and the proprietary silane primer.     

The Influence of Ceramic Surface Treatments on the Micro-shear Bond Strength of Composite Resin to IPS Empress 2

Purpose: An increasing demand for esthetic restorations has resulted in the development of new ceramic systems, but fracture of veneering ceramics still remains the primary cause of failure. Porcelain repair frequently involves replacement with composite resin, but the bond strength between composite resin and all‐ceramic coping materials has not been studied extensively. The purpose of this study was to evaluate the influence of different ceramic surface treatments on the micro‐shear bond strength of composite resin to IPS Empress 2 coping material. Materials and Methods: Sixteen 7 × 7 × 1 mm³ lithia disilicate‐based core ceramic plates were fabricated using the lost wax technique. The plates were divided into eight groups, and eight different surface treatments were performed: (1) no treatment (NT); (2) airborne‐particle abrasion with 50‐μm alumina particles (Al); (3) acid etching with 9.6% hydrofluoric acid for 1 min (HF); (4) silane coating (S); (5) AlHF; (6) AlS; (7) HFS; and (8) AlHFS. Then, ten composite resin cylinders (0.8‐mm diameter × 0.5‐mm height) were light‐polymerized onto the ceramic plates in each group. Each specimen was subjected to a shear load at a crosshead speed of 0.5 mm/min until fracture occurred. The fracture sites were examined with scanning electron microscopy (SEM) to determine the location of failure during debonding and to examine the surface treatment effects. One‐way analysis of variance (ANOVA) and multiple comparison (Dunnet T3) tests were used for statistical analysis of data. Results: The mean micro‐shear bond strength values (SD) in MPa were—NT: 4.10 (3.06), Al: 7.56 (4.11), HF: 14.04 (2.60), S: 14.58 (2.14), AlHF: 15.56 (3.36), AlS: 23.02 (4.17), HFS: 24.7 (4.43), AlHFS: 26.0 (3.71). ANOVA indicated the influence of surface treatment was significant (p < 0.0001). SEM analysis did not reveal entirely cohesive failure in any composite or ceramic. Conclusion: The micro‐shear bond strength of a composite resin to IPS Empress 2 was significantly different depending on the surface treatment method. Among the investigated methods, silane coating after airborne‐particle abrasion and etching was the most effective surface treatment in terms of bond strength increase.     

不同偶联剂和粘接剂对烤瓷瓷面与金属托槽抗剪切强度影响的体外研究

目的研究不同类型硅烷偶联剂和粘接剂对烤瓷瓷面与金属托槽之间抗剪切强度的影响。方法将90个烤瓷瓷面行水砂纸打磨去釉,HF酸蚀处理,根据硅烷偶联剂的不同随机分为甲乙丙3组,再根据使用粘接剂不同每组下分3小组,分别用3种不同粘接剂,将90个金属托槽粘接于烤瓷瓷面,托槽粘结60 min后经37℃恒温人工唾液水浴孵化24 h,使用Instron万能材料力学试验机测定样本抗剪切强度。结果使用硅烷偶联剂组抗剪切强度比未使用硅烷偶联剂组大(P<0.05);2种硅烷偶联剂组之间抗剪切强度差异无显著性(P>0.05);光固化复合树脂粘接剂组抗剪切强度大于其他粘接剂组(P<0.05);未使用硅烷偶联剂组瓷面破损指数明显小于使用硅烷偶联剂组(P<0.05)。结论硅烷偶联剂能有效增加烤瓷瓷面和金属托槽之间的抗剪切强度,光固化复合树脂粘接剂与双组份硅烷偶联剂合用可获得最大的抗剪切强度。     

Porcelain surface-conditioning techniques and the shear bond strength of ceramic brackets

The aim of this study was to compare the effects of various porcelain surface-conditioning techniques, used either alone or in combination, on the shear bond strength (SBS) of ceramic brackets cured with a light emitting diode (LED). Thirty glazed porcelain facets were randomly divided into three groups of 10. In group I, the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid (HFA) for 2 minutes before silane application, in group II, the porcelain surfaces were sandblasted with aluminium oxide particles, etched with 9.6 per cent HFA for 2 minutes, and silane applied, and in group III, the porcelain surfaces were sandblasted with aluminium oxide particles before silane application. Spirit ceramic brackets were bonded with a light-cured composite resin (Light Bond) and a LED. All specimens were stored in distilled water at 37 degrees C for 24 hours and thermocycled. Bond strength was determined in shear mode at a crosshead speed of 0.5 mm/minute until fracture occurred. Analysis of variance indicated a significant difference between groups (P < 0.001). The lowest SBS was found in group III (5.46 +/- 1.34, P < 0.001). No significant difference was found between group I (11.38 +/- 1.65) and group II (10.45 +/- 1.15; P > 0.05). Surface treatment with HFA and a silane coupling agent produced the highest bond strength. Sandblasting before HFA and silane application did not significantly increase bond strength. Silane application to sandblasted porcelain provided poor results in vitro and clinical trials are needed to determine its reliability for bonding ceramic brackets to ceramic crowns.     

Influence of ceramic thickness and polymerization mode of a resin luting agent on early bond strength and durability with a lithium disilicate-based ceramic system

STATEMENT OF PROBLEM: Attenuation of polymerization light energy by translucent all-ceramic materials may result in insufficient polymerization of underlying resin luting agents and inadequate early bond strength and durability. There is little information regarding the selection of an appropriate polymerization mode for cementing translucent all-ceramic restorations. PURPOSE: The purpose of this study was to evaluate the influence of ceramic thickness and polymerization mode on the early bond strength and bond durability of a lithium disilicate-based ceramic system. MATERIAL AND METHODS: The occlusal surfaces of 120 extracted, intact, human third molars were sectioned to expose a flattened area of dentin. The surface was etched with 32% phosphoric acid, and a single-step adhesive (One-Step) was applied to the etched dentin surfaces. Ceramic specimens (Empress 2), 6 mm in diameter and 1 mm, 1.5 mm, or 2 mm thick (n=40 per group), were fabricated using fluoropolymer resin matrixes. Each specimen was ground flat. Following hydrofluoric acid etching and silane treatment, ceramic discs of each thickness were further divided into 2 groups (n=20 per group) and bonded to the dentin surfaces with a dual-polymerized resin luting agent (Illusion), either with a catalyst (dual polymerization) or without a catalyst (light polymerization). A shear bond test was performed after 10 minutes (n=10) or after 24 hours following 1000 thermal cycles between 5 degrees C and 55 degrees C and a dwell time of 30 seconds (n=10). Debonded dentin surfaces were examined with SEM. The data were analyzed with 3-way analysis of variance (ANOVA) (alpha=.05). RESULTS: The shear bond strengths ranged between 13.2 +/- 4.1 MPa and 15.9 +/- 2.0 MPa. Three-way ANOVA revealed that ceramic thickness, polymerization mode, storage time, or combinations of these parameters did not influence shear bond strength. The location of failure for all specimens was adhesive, between the dentin surface and bonding agent. CONCLUSION: Both light polymerization and dual polymerization provided similar early shear bond strengths for the lithium disilicate-based ceramic system (Empress 2). The bond strength was not dependent on the thickness of the ceramic material tested. Durability of the bond was similar for both of the polymerization modes.     

Tensile bond strength of ceramic orthodontic brackets bonded to porcelain surfaces

The aim of this study was to compare various surface treatment methods to define the procedure that produces adequate bond strength between ceramic brackets and porcelain. The specimens used in this study, 60 porcelain tabs, were produced by duplication of the labial surface of a maxillary first premolar. The 6 different preparation procedures tested were: (1) sandblasting with 50 microm aluminum oxide in a sandblasting device, (2) application of silane to the porcelain and the bracket base, (3) sandblasting followed by application of silane, (4) acid etching with 9.6% hydrofluoric acid, (5) acid etching with 9.6% hydrofluoric acid followed by application of silane, and (6) sandblasting followed by application of 4-Meta adhesive. The ceramic brackets were bonded with no-mix orthodontic bonding material. A bonding force testing machine was used to determine tensile bond strengths at a crosshead speed of 0.5 mm per second. The results of the study showed that porcelain surface preparation with acid etching followed by silane application resulted in a statistically significant higher tensile bond strength (P < .05). Sandblasting the porcelain surface before silane treatment provided similar bond strengths, but sandblasting or acid etching alone were less effective. Silane application was recommended to bond a ceramic bracket to the porcelain surface to achieve bond strengths that are clinically acceptable.     

Comparative tensile strengths of brackets bonded to porcelain with orthodontic adhesive and porcelain repair systems

The acceptance of simplified technical procedures that minimize clinical effort is exemplified by the popularity of direct bonding. This study (1) measured the comparative tensile bond strengths of brackets bonded directly in vitro to both glazed and deglazed porcelains by the use of five adhesive systems, and (2) recorded failure sites. System 1+, Enamelite 500, Isopast/Silanit, and Concise/Scotchprime proved to have strengths that should be acceptable clinically. Ultra-bond produced a bond that was significantly less in strength as compared with the other four systems. There was no significant difference in the bond of glazed and deglazed porcelains. Diamond polishing paste was better at restoring the porcelain surface to original smoothness in comparison with polishing stones. Irreversible damage to the porcelain surface may result from the bonding procedure.     

Effects of light-emitting diode and halogen light curing techniques on ceramic brackets bonded to porcelain surfaces

The objectives of this study were to test the efficiency of LED curing devices in bonding ceramic brackets to porcelain surfaces and to compare the effects of LED and halogen curing techniques on shear bond strength of ceramic brackets. A total of 20 glazed porcelain facets were randomly divided into two groups of 10. Porcelain surfaces were etched with 9.6% hydrofluoric acid for 2 minutes, and silane was applied on the etched porcelain surface. Ceramic brackets were bonded with an LC composite resin cured with soft start mode LED and a halogen light. Bond strengths, as determined in the shear mode, were higher in the LED group (P < .001). LED curing units with the soft start polymerization mode were more effective than halogen curing units in bonding ceramic brackets on porcelain surfaces. The type of curing light must be considered as an important factor affecting bond strength of ceramic brackets on porcelain surfaces.     

Assessment of an Indirect Metal Ceramic Repair System

Purpose: This study was designed to compare an alternative indirect treatment to repair fractured or chipped veneering metal ceramic using recently developed ultra‐low‐fusing ceramics. Materials and Methods: One conventional feldspathic ceramic, Vita Omega, and three ultra‐low‐fusing ceramics (ULFC), Finesse, Duceram LFC, and Vision‐low, were used. Forty ceramic specimens were prepared and divided into two groups. Group I (n = 20) was designed for bond strength testing. It comprised four subgroups (A, B, C, D): one Ceramic‐resin (A) and three Ceramic‐ULFC disc specimens of different diameters (B, C, D). Group II was composed of repaired ceramic discs using direct and indirect repair methods for biaxial testing. It was comprised of five subgroups: the fractured discs from subgroup A; Omega discs (n = 20) formed the repaired specimens of the four remaining subgroups: B, C, D, E. Data were presented as means and standard deviation (SD) values. One‐way analysis of variance (ANOVA) was used for comparison between means. Tukey's post hoc test was used for pairwise comparison between the means when ANOVA test was significant. The significance level was set at p≤ 0.05. Results: Within group I, Omega‐Ducera LFC showed the statistically highest mean bond strength (25.8 MPa) values, followed by Omega‐Finesse (15.8 MPa). No statistically significant difference was apparent between Omega‐Vision (9.3 MPa) and the control Omega‐Composite group (7.5 MPa). Regarding group II, the Control Omega subgroup showed statistically the highest mean biaxial strength values (168.8 MPa). No statistically significant difference was evident between the values of Omega‐Finesse (78.7 MPa), Omega‐Vision (78.4 MPa), and Omega‐Composite (82.5 MPa). Omega‐Ducera LFC subgroup, showed statistically the lowest mean values (53 MPa). Conclusions: Omega‐Ducera LFC yielded the statistically highest mean bond strength values, and the lowest biaxial strength values. All values were within the reported bond strength values for resin repair. All the tested groups showed significantly lower values compared to the initial biaxial strength mean values of the Omega ceramic; however, two of the tested ULFC (Vision, Finesse), recorded means that were statistically equal to the resin‐ceramic direct subgroup. Duceram LFC showed the lowest values, probably due to its totally glass composition, which showed low strength values of the repaired specimens. The recorded bond and biaxial values suggest that indirect repair of fractured LFC using some ULFC ceramics may offer an alternative solution to the traditional direct resin repair method; however, the choice of the used ceramic should be one containing some leucite crystals. Further studies are needed to investigate the long‐term performance of the proposed repair treatment.     

不同粘接剂对烤瓷瓷面与金属托槽间剪切强度影响的体外研究

目的 研究不同粘接剂对烤瓷瓷面与金属托槽间剪切强度的影响.方法 40个烤瓷瓷面经打磨、氢氟酸酸蚀、冲洗干燥、硅烷偶联剂处理瓷面后,再根据使用粘接剂的不同分为A组:光固化复合树脂粘接剂、B组:单组份化学固化复合树脂粘接剂、C组:树脂改良型光固化玻璃离子粘接剂、D组:双组份化学固化复合树脂粘接剂.将40个金属托槽粘接于烤瓷瓷面,经水浴孵化24 h后测得样本剪切强度,并进行统计分析.结果 A组剪切强度大于其他组(P＜0.05),C组剪切强度小于B组(P＜0.05),D组与B、C组剪切强度差异无统计学意义(P＞0.05).结论 光固化复合树脂粘接剂可获得最大的剪切强度,树脂改良型光固化玻璃离子粘接剂对金属托槽与烤瓷瓷面的粘接效果欠佳.