OBJECTIVE: To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. METHODS: A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. RESULTS: There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 +/- 1.39 Ncm) than for the machined ones (2.05 +/- 1.07 Ncm) (p < 0.01). The interfacial strengths, converted from PRT, were calculated at 10.6 MPa and 5.74 MPa for the anodized and machined group implants, respectively. CONCLUSIONS: Anodization of orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage.
Rabbits ; Retention (Psychology) ; Shear Strength ; Tibia ; Torque

The purpose of this study was to compare the bracket placement and the shear bond strength of indirect-bonded brackets with those of direct-bonded ones. Forty eight extracted human teeth were collected and attached with brackets and tested on shear bond strength, using Instron. Fourteen patients from Wonkwang University Dental Hospital were selected for direct bonding of brackets and their teeth were measured on bracket angulation and bracket height. The obtained results were as follows: 1. The shear bond strengths of incisors were higher in direct-bonding,group, rather than in-direct-bonding group. But, the shear bond strength of premolars showed no significant differences between groups. 2. The bracket angulations of indirect-bonding group were preciser than those of direct-bonding group, especially in upper first premolars, lower lateral incisors, canines, premolars. 3. In bracket height, there were no significant differences between groups.
Bicuspid ; Humans ; Incisor ; Shear Strength* ; Tooth

OBJECTIVETo investigate the effect of three types of veneering porcelain on the bending strength of KAVO Y-TZP/porcelain layered structure.

METHODSKAVO zirconia ceramics were used as the substructure. To form Y-TZP/porcelain bilayered structure, a leucite-based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite-based veneering porcelains were fired on the zirconia substructures by either slip-casting or pressed-on technique with or without liner coverage. The bending strength was tested according to ISO 6872 standard, and the veneered surfaces of the fracture samples were analyzed by scanning electron microscopy (SEM).

RESULTSFor covering KAVO zirconia core material, the conventional veneering slurry-porcelain combined with liner or wash firing had significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive failure.

CONCLUSIONThin layer sintering using washbake program or liner on KAVO zirconia surface increases the surface wettability, and this procedure may be indispensable when veneering on the surface of dental zirconia.

OBJECTIVETo observe effects of fluid shear stress strength on mRNA expression of ATP6V1a1 in rat polarized osteoclasts.

METHODSRat polarized osteoclasts suffered 0.0 (control group), 0.9, 2.9, 8.7 and 26.3 dynes/cm2 fluid shear stress for 30 min. mRNA expression of ATP6V1a1 was detected by Real-Time fluorescent quantitation PCR.

RESULTSmRNA expression of ATP6V1a1 in 0.0 (control group), 0.9, 2.9, 8.7 and 26.3 dynes/cm2 groups was (1.14 +/- 0.06) x 10(6), (1.62 +/- 0.09) x 10(6), (2.28 +/- 0.13) x 10(6), (3.24 +/- 0.18) x 10(6), (9.16 +/- 0.53) x 10(6) copy numbers, respectively (P < 0.05).

CONCLUSIONIn the present study, polarized osteoclasts are sensitive to fluid shear stress. mRNA expression of ATP6V1a1 has increscent tendency along with increasing of fluid shear stress strength.

STATEMENT OF PROBLEM: Zirconia-based restorations have the common technical complication of delamination, or porcelain chipping, from the zirconia core. Thus the shear bond strength between the zirconia core and the veneering porcelain requires investigation in order to facilitate the material's clinical use. PURPOSE: The purpose of this study was to evaluate the bonding strength of the porcelain veneer to the zirconia core and to other various metal alloys (high noble metal alloy and base metal alloy). MATERIAL AND METHODS: 15 rectangular (4x4x9mm) specimens each of zirconia (Cercon), base metal alloy (Tillite), high noble metal alloy (Degudent H) were fabricated for the shear bond strength test. The veneering porcelain recommended by the manufacturer for each type of material was fired to the core in thickness of 3mm. After firing, the specimens were embedded in the PTFE mold, placed on a mounting jig, and subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.5mm/min until fracture. The average shear strength (MPa) was analyzed with the one-way ANOVA and the Tukey's test (alpha= .05). The fractured specimens were examined using SEM and EDX to determine the failure pattern. RESULTS: The mean shear strength (+/- SD) in MPa was 25.43 (+/- 3.12) in the zirconia group, 35.87 (+/- 4.23) in the base metal group, 38.00 (+/- 5.23) in the high noble metal group. The ANOVA showed a significant difference among groups, and the Tukey's test presented a significant difference between the zirconia group and the metal group. Microscopic examination showed that the failure primarily occurred near the interface with the residual veneering porcelain remaining on the core. CONCLUSION: There was a significant difference between the metal ceramic and zirconia ceramic group in shear bond strength. There was no significant difference between the base metal alloy and the high noble metal alloy.
Ceramics ; Collodion ; Dental Porcelain ; Fires ; Fungi ; Polytetrafluoroethylene ; Shear Strength ; Zirconium

STATEMENT OF PROBLEM: The aims of the study were to evaluate the effect of current surface conditioning methods on the bond strength of a resin composite luting cement bonded to ceramic surfaces and to identify the optimum cement type. MATERIAL AND METHODS: The sixty zirconia ceramic specimens(10 per group) with EVEREST milling machine and 60 tooth block were made. The zirconia ceramic surface was divided into two groups according to surface treatment: (1) airborne abrasion with 110micrometeraluminum oxide particles; (2) Rocatec system, tribochemical silica coating. The zirconia ceramic specimens were cemented to tooth block using resin cements. The tested resin cements were Rely X ARC, Panavia F and Superbond C and B. Each specimen was mounted in a jig of the universal testing machine for shear strength. The results were subjected to 2-way ANOVA and Post hoc tests was performed using Tukey, Scheffe, and Bonferroni test. RESULTS: The mean value of shear bond strength(MPa) were as follows: RelyXARC(+Al2O3),5.35+/-1.69; RelyXARC(+Rocatec),8.50+/-2.13; PanaviaF(+Al2O3),9.58+/-1.13; PanaviaF(+Rocatec),12.98+/-1.71; Superbond C and B(+Al2O3),8.27+/-2.04; Superbond C and B(+Rocatec),14.46+/-2.39. There was a significant increase in the shear bond strength when the ceramic surface was subjected to the tribochemical treatment(Rocatec 3M) in all cement groups(P<0.05). Bonding strengths of cements applied to samples treated with Al2O3 were compared; Rely X ARC showed the lowest values, whereas Panavia F cement showed higher value than that of Superbond C and B group with no statistical significance. When the bond strength of cements with Rocatec treatment was compared, Rely X ARC showed lowest values. Overall, it was apparent that tribochemical treated Super-Bond possessed higher mean bond strength.(14.46MPa; P<0.05) than that of Panavia F cement group with no significance. CONCLUSIONS: Silica coating followed silanization(Rocatec treatment) increase the bond strength between resin cement and zirconia ceramic. Panavia F containing phosphate monomer and Superbond C and B comprised of 4-META tend to bond chemically with zirconia ceramic, thus demonstrating higher bond strength compared to BisGMA resin cement. Superbond C and B has shown to have highest value of bonding strength to zirconia ceramic after Rocatec treatment compared to other cement.
Ceramics* ; Resin Cements* ; Shear Strength ; Silicon Dioxide ; Tooth

PURPOSE: The purpose of this study was aimed to compare the shear bond strength on dentin of three dentin bonding agents and two resin cements used in conjunction with self-cured composite resin core material. MATERIAL AND METHOD: Control group and six experimental groups were divided for this study. Control group was designated as specimens bonded with Tenure A & B(R). Experimental groups were as follows: PB-BL group : specimens bonded with PrimeandBond NT(R), BondLink(R). SB-BL group : specimens bonded with SingleBond(R), BondLink(R). PB group : specimens bonded with PrimeandBond NT(R) SB group : specimens bonded with SingleBond(R). PF group : specimens bonded with Panavia-F(R). BI group : specimens bonded with Bistite II(R). All specimens were stored in 37degrees C distilled water for 24 hours, followed by the shear bond strength was tested by universal testing machine. The data was analysed statistically by Mann-Whitney test. RESULTS: 1. For PrimeandBond NT(R) and SingleBond(R), the shear bond strength was 0.24 MPa and 7.19 MPa each by each, while Tenure A & B(R) group control was measured at 13.93 MPa (p<0.05). Especially for PrimeandBond NT(R), it did not get conjunction with dentin. 2. For PrimeandBond NT(R) and SingleBond(R) using BondLink(R), there was no significant difference as a result of 11.73 MPa and 14.00 MPa each by each (p<0.05). 3. For Panavia-F(R) and Bistite II(R), they showed the highest shear bond strength as measured by 18.24 MPa and 16.09 MPa each(p<0.05).
Dentin* ; Dentin-Bonding Agents* ; Resin Cements* ; Shear Strength ; Water

The effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer was studied. The samples were divided into 4 groups according to 4 different enamel surface conditions: Group A: dry; Group B: saliva contamination before priming; Group C: saliva contamination after priming, and Group D: saliva contamination before and after priming. Stainless steel brackets were bonded in each test group with a light-cured composite resin (TransbondXT 3M). The shear bond strength was determined in the first 30 min after bonding. The analysis of variance indicated that the shear bond strengths of the 4 groups were significantly different (F = 11.89, P < 0.05). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=4.6 +/- 1.7 MPa) shear bond strength than either the control group (=8. 8 +/- 1.9 MPa) or the groups where contamination occurred either before ( = 7.9 +/- 2.0 MPa) or after (= 6. 9 +/- 1.5 MPa) the application of the primer. It was concluded that the new acid-etch primer could maintain adequate shear bond strength if contamination occurred either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer could significantly reduce the shear bond strength of orthodontic brackets.
Acid Etching, Dental ; Orthodontic Brackets ; Saliva ; Shear Strength

The purpose of this study was to compare the shear bond strength obtained from ceramic and plastic brackets bonded with various light-cured adhesives and to evaluate their debonded failure sites. Plastic brackets, Transcend 6000, Signature and Starfire TMB brackets were bonded with Orthobond, Light Bond and Transbond on one hundred forty extracted human premolar teeth as manufacturer's descriptions. After thermocycling the brackets were debonded with an Instron universal testing machine and the debonded bracket base surfaces were inspected under stereoscope to evaluate the failure sites. Also the shear bond strength and failure patterns with different curing time and with two different source of light were compared. The results were as follows. 1. There were no statistically significant differences among the mean shear bond strength of Orthobond, Light Bond and Transbond in a same bracket group except Plastic bracket group(p<0.05). 2. The mean shear bond strength of each adhesive with different bracket groups showed statistically significant differences. Starfire TMB showed the highest shear bond strength among the brackets in this study, but there was no statistically significant difference with Transcend 6000 while there was statistically significant difference with Signature.(p<0.05) 3. The various bonding failure patterns were occurred among different bracket groups but most of failure sites were bracket base-adhesive interfaces. 4. There were no statistically significant differences in shear bond strength between the groups with curing time of 10 second and 20 second, and between the groups with two different sources of light as long as sufficient light intensity(above 400mW/cm2) were provided(p<0.05). According to the result, it should be considered in clinical use of ceramic bracket with light-cured adhesives that the shear strengths of ceramic brackets were influenced by the retention from of bracket base as well as the composition of bracket and there was no difference in the shear bond strength among various light-cured adhesives used in this study.
Adhesives* ; Bicuspid ; Ceramics* ; Humans ; Plastics ; Shear Strength ; Tooth

PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) of an indirect resin composite (IRC) to the various resin matrix ceramic (RMC) blocks using different surface treatments. MATERIALS AND METHODS: Ninety-nine cubic RMC specimens consisting of a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) were divided randomly into three surface treatment subgroups (n = 11). In the experimental groups, untreated (Cnt), tribochemical silica coating (Tbc), and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser irradiation (Lsr) with 3 W (150 mJ/pulse, 20 Hz for 20 sec.) were used as surface treatments. An indirect composite resin (IRC) was layered with a disc-shape mold (2 × 3 mm) onto the treated-ceramic surfaces and the specimens submitted to thermal cycling (6000 cycles, 5 – 55℃). The SBS test of specimens was performed using a universal testing machine and the specimens were examined with a scanning electron microscope to determine the failure mode. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α=.05). RESULTS: According to the two-way ANOVA, only the surface treatment parameter was statistically significant (P<.05) on the SBS of IRC to RMC. The SBS values of Lsr-applied RMC groups were significantly higher than Cnt groups for each RMC material, (P<.05). Significant differences were also determined between Tbc surface treatment applied and untreated (Cnt) PIHC materials (P=.039). CONCLUSION: For promoting a reliable bond strength during characterization of RMC with IRC, Nd:YAG laser or Tbc surface treatment technique should be used, putting in consideration the microstructure and composition of RMC materials and appropriate parameters for each material.
Aluminum ; Ceramics ; Composite Resins ; Fungi ; Shear Strength ; Silicon Dioxide ; Yttrium