Porcelain repair - Influence of different systems and surface treatments on resin bond strength

PURPOSE: The purpose of this study was to evaluate the bond strength of composite resin on the fracture surface of metal-ceramic depending on the repair systems and surface roughening methods. MATERIALS AND METHODS: A total of 30 disk specimens were fabricated, 15 of each were made from feldspathic porcelain and nickel-chromium base metal alloy. Each substrate was divided into three groups according to the repair method: a) application of repair system I (Intraoral Repair Kit) with diamond bur roughening (Group DP and DM), b) application of repair system I with airborne-particle abrasion (Group SP and SM), and c) application of repair system II (CoJet Intraoral Repair System, Group CP and CM). All specimens were thermocycled, and the shear bond strength was measured. The data were analyzed using the Kruskal-Wallis analysis and the Mann-Whitney test with a significance level of 0.05. RESULTS: For the porcelain specimens, group SP showed the highest shear bond strength (25.85 +/- 3.51 MPa) and group DP and CP were not significantly different. In metal specimens, group CM showed superior values of bond strength (13.81 +/- 3.45 MPa) compared to groups DM or SM. CONCLUSION: Airborne-particle abrasion and application of repair system I can be recommended in the case of a fracture localized to the porcelain. If the fracture extends to metal surface, the repair system II is worthy of consideration.

Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

PURPOSE: The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS: A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm x 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 microm silica oxide particles (Cojet(TM) Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at alpha=.05. RESULTS: Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION: Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

Effect of tribochemical silica coating on the shear bond strength of rebonded monocrystalline ceramic brackets / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to investigate the effect of tribochemical silica coating on the shear bond strength (SBS) of rebonded ceramic brackets using nano-filled flowable composite resin. METHODS: A total of 60 premolars were prepared and divided into 4 equal groups as follows: Tribochemical silica coating (TC) + Transbond XT (XT), TC + Transbond supreme LV (LV), Sandblast treatment (SA) + XT, SA + LV. Treated ceramic brackets were rebonded on the premolars using each adhesive. All samples were tested in shear mode on a universal testing machine. RESULTS: SBS of silica coated groups were high enough for clinical usage (TCLV: 10.82 +/- 1.82 MPa, TCXT: 11.50 +/- 1.72 MPa). But, SBS of the sandblast treated groups had significantly lower values than the tribochemical silica coated groups (SALV, 1.23 +/- 1.16 MPa; SAXT, 1.76 +/- 1.39 MPa; p< 0.05). There was no difference between the shear bond strength by type of adhesive. In the silica coated groups, 77% of the samples showed bonding failure in the adhesive. In the sandblast treated group, all bonding failures occurred at the bracket-adhesive interface. CONCLUSIONS: The result of this study suggest that newly introduced nano-filled flowable composite resin and tribochemical silica coating application on debonded ceramic bracket bases can produce appropriate bond strengths for orthodontic bonding.