Effect of Light-Cured Resin Cement Application on Translucency of Ceramic Veneers and Light Transmission of LED Polymerization Units.

PURPOSE: To evaluate the effect of light-cured resin cement application based on etching and silanization on the translucent property of ceramic veneers in different thicknesses, testing the hypothesis that the surface treatment and subsequent resin cement application could influence the translucency of ceramic veneers. The relationship between translucency of ceramic veneers and light transmission irradiated by LED polymerization units was also determined. MATERIALS AND METHODS: 40 specimens (10 mm diameter) were fabricated from IPS e.max Press HT A2 ceramic ingots, and polished to 0.3 ± 0.01 mm, 0.5 ± 0.01 mm, 0.7 ± 0.01 mm, 1.0 ± 0.01 mm, and 1.5 ± 0.01 mm thick (n = 8/group). One surface of each disc was etched with HF acid, silanized with Monobond-S, and applied with a light-cured resin cement (Variolink N Transparent Base). Before and after the above procedure, the total luminous transmittance (τ) of all specimens was assessed by a spectrophotometer in a wavelength range of 380-780 nm. A handheld radiometer was used to measure the light intensity irradiated by three LED polymerization units. Light transmission (LT) through ceramic specimens after resin cement application was calculated. Data were statistically analyzed using two-way ANOVA (p = 0.05) and Tukey's test. The correlation between translucency (τ) of ceramic veneers after resin cement application and light transmission (LT) of curing units was statistically evaluated using Spearman correlation test (p = 0.05). RESULTS: With the increase of ceramic thickness, the transmittance decreased significantly (p < 0.05). For the 0.3-mm, 0.5-mm, and 0.7-mm-thick groups, the transmittance of ceramic specimens was statistically significantly lower after resin cement application (p < 0.05). The r value of Bluephase C8 was 0.988, 0.977 for Bluphase, and 0.883 for Bluephase 20i, indicating that the light transmission (LT%) was positively correlated to the translucency of ceramic veneers, regardless of the type of curing units. CONCLUSION: After the light-cured resin cement application based on etching and silanization, the ceramic veneers (less than 0.7-mm thick) were less translucent, and the translucency decreased when the thickness increased. Because of the lower translucency of ceramic veneers, the light intensity of LED units transmitted to resin layer would decrease when curing.

Intrusion of supraerupted maxillary molar using a high interim restoration on the defective opposing tooth: a clinical report.

Wear, extraction, or fracture of all or part of a mandibular first molar can lead to the supraeruption of the opposing maxillary molar, resulting in occlusal interference and lack of restoration space. This report describes a method to gain sufficient vertical space for permanent restoration. A direct composite resin restoration was placed on the occlusal surface of a lower molar, intentionally making the interim restoration high and intruding the maxillary molar. After 6 weeks, the extruded tooth returned to the desired position, and functional occlusion was restored, enabling a ceramic restoration on the mandibular molar. No marked adverse sensory reaction was reported in this therapeutic process, and no deleterious signs were detected in the teeth, periodontium, or temporomandibular joints. The simple treatment type was effective, noninvasive, and time saving, while also preserving maximum tooth structures.

[Effect of surface treatment on the three-point bend bonding strength between pure titanium fabricated by selective laser melting and porcelain].

PURPOSE: To evaluate the effect of surface treatment on bonding strength between pure titanium formed by selective laser melting and porcelain. METHODS: Pure titanium strips (64) and cobalt-chromium alloy strips (16) were laser machined to meet ISO 9693 standards. The pure titanium specimens were divided into 4 groups according to the sandblasting pressure and interlayer material. The sandblasting pressure of 0.25 MPa of bonder porcelain group was TB1, the sandblasting pressure of 0.25 MPa of gold coating group was TG1, the sandblasting pressure of 0.45 MPa of bonder porcelain group was TB2, and the sandblasting pressure of 0.45 MPa of the gold coating group was TG2(n=16). After porcelain fusing, half of the specimens in each group were tested for three-point bend bonding strength, and the other half were tested after 10 000 cycles of thermal cycling(n=8). The bonding strength of cobalt-chromium alloy after sandblasting at 0.25 MPa and 0.45 MPa was taken as the control group and recorded as group C1, C2(n=8). The bonding strength was tested using classical three-point bending experiment. The surface roughness of pure titanium was measured by laser scanning confocal microscope(LSCM). Field emission scanning electron microscopy(FE-SEM) was used to observe the interface morphology of titanium-ceramic. The surface morphology of titanium after porcelain stripping was observed with stereomicroscope and fracture modes were analyzed by it. Graphpad Prism 8.0 software package was used for statistical analysis of the data. RESULTS: The bonding strength of group TG2 was (40.16±3.97) MPa and (37.38±2.39) MPa of group TG1, which were significantly higher than that of group TB2 (36.32±1.44) MPa and group TB1 (33.75±2.31) MPa (P＜0.05). The bonding strength of group TB2 with 0.45 MPa sandblasting was significantly higher than that of group TB1 with 0.25 MPa sandblasting (P＜0.05). There was no significant decrease in titanium-ceramic bonding strength before and after thermal cycling. When the sandblasting pressure increased from 0.25 MPa to 0.45 MPa, the roughness increased significantly (P＜0.05). The fracture modes were mixed. CONCLUSIONS: Under the conditions of this study, gold coating can significantly improve the bonding strength of Ti22 porcelain and SLM pure titanium than bonder porcelain, and increase of sandblasting pressure can further improve the bonding strength of titanium-porcelain. After 10 000 cycles of thermal cycling, the titanium-porcelain bonding strength did not decrease significantly.

Effect of veneering techniques on color and translucency of Y-TZP.

PURPOSE: This study compared the color parameters and total luminous transmittance of disc specimens by different veneering techniques in order to examine the effect of veneering technique on esthetics of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) all-ceramic restorations. MATERIALS AND METHODS: Thirty disc specimens (10-mm diameter, 0.50 +/- 0.01 mm thick) were fabricated of IPS e.max ZirCAD core material, and ZL1 IPS e.max ZirLiner (0.10-mm thick) was layered. The specimens were randomly divided into three groups (n = 10/group). Group ZP (fully anatomical technique) was veneered 0.60 mm by heat-pressing IPS e.max ZirPress fluorapatite glass-ceramic ingots; Group ZC (traditional layering technique) was veneered 0.60 mm by condensing and sintering IPS e.max Ceram low-fusing nano-fluorapatite veneering porcelain; Group ZPC (cutback technique) was veneered by partially pressed ingots and subsequently layered 0.30 mm with veneering porcelain. Color parameters (L*, a*, b*) and total luminous transmittance (tau) of zirconia core discs and core and veneer specimens were measured with ShadeEye NCC dental colorimeter and spectrophotometer, respectively. Color saturation (C*ab) and color difference (DeltaE) were calculated using color difference formula. One-way analysis of variance (ANOVA) combined with a Tukey multiple-range test were used to analyze the data (alpha= 0.05). RESULTS: As to ZP, ZPC, and ZC groups, the value of a* increased (-1.35 +/- 0.07, -0.64 +/- 0.06, -0.36 +/- 0.05, respectively) (p < 0.05); b* decreased (27.01 +/- 0.07, 25.48 +/- 0.11, 23.28 +/- 0.25, respectively) (p < 0.05); and C*ab decreased (27.04 +/- 0.08, 25.49 +/- 0.11, 23.28 +/- 0.25, respectively) (p < 0.05). L* value and total luminous transmittance were highest in ZP group (87.53 +/- 0.48, 1.64 +/- 0.03, respectively), and lowest in ZPC group (82.14 +/- 0.18, 1.47 +/- 0.01, respectively) (p < 0.05). CONCLUSIONS: Y-TZP all-ceramic restoration veneered by fully anatomical technique was the most transparent and lightest, while restorations veneered by cutback technique were the least translucent and the darkest.

Comparative pharmacokinetics and pharmacodynamics of a PEGylated recombinant human growth hormone and daily recombinant human growth hormone in growth hormone-deficient children.

OBJECTIVE: Recombinant human growth hormone (rhGH) replacement therapy in children generally requires daily subcutaneous (sc) injections, which may be inconvenient for patients. Jintrolong® is a PEGylated rhGH with the purpose of weekly sc injections. The aim of the current study was to examine the pharmacokinetics, pharmacodynamics, safety, and tolerability of multiple sc doses of Jintrolong® vs daily doses of rhGH. DESIGN AND METHODS: Twelve children with growth hormone deficiency participated in this single-center, open-label, crossover Phase I trial. All subjects received daily sc injections of rhGH at 0.0286 mg/kg/d for 7 days, followed by a 4-week washout period and six weekly doses of Jintrolong® at 0.2 mg/kg/w. RESULTS: In comparison with rhGH, sc injection of Jintrolong® produced a noticeably higher C max, significantly longer half-life (t 1/2), and slower plasma clearance, signifying a profile suitable for long-term treatment. The ratio of the area under the concentration vs time curve (AUC) after the seventh and first injections (AUC(0-∞)7th/AUC(0-∞)1st) of rhGH was 1.02, while the AUC(0-∞)6th/AUC(0-∞)1st of Jintrolong ® was 1.03, indicating no accumulation of circulating growth hormone. There was no significant difference in the change in insulin-like growth factor-1 expression produced by 7 days of sc rhGH and weekly Jintrolong® injections. There were no severe adverse events during the trial. CONCLUSION: The elimination rate of Jintrolong® was slower than that of sc rhGH. No progressive serum accumulation of Jintrolong® was found. The changes in insulin-like growth factor-1 expression produced by rhGH and Jintrolong® were comparable, indicating similar pharmacodynamics. Our results demonstrate that Jintrolong® is suitable for long-term growth hormone treatment in children with growth hormone deficiency.

[Effect of hydrofluoric acid etching time and resin bonding on the flexural strength of lithium disilicate glass ceramic].

OBJECTIVE: To analyze the effect of hydrofluoric acid(HFA) etching time and resin bonding on the flexural strength of IPS e.max® Press glass ceramic, and evaluate the efficacy of resin cements to seal the cracks of the etched ceramic. METHODS: Two hundred and twenty-five bars (25.0 mm×3.0 mm×2.0 mm) were made from IPS e.max® Press ingots using lost-wax, hot-pressed ceramic fabrication technology and randomly divided into five groups, forty-five each.In each group, the surfaces of ceramic bars were etched by 9.5% HFA gel for 0, 20, 40, 60 and 120 s respectively. Three specimens from each group were selected to observe the microstructure by the field emission scanning electron microscope (FE-SEM). Then each group were randomly subdivided into two subgroups (n = 20).One subgroup were coverd with a thin (approximately 0.1 mm) layer of resin cement (Variolink N), whereas the other subgroup remained unaltered.Half of the specimens were stored in 37°C water bath for 24 h and the other half went through thermocycle 10 000 times before 3-point bending test to determine their flexural strength.Interfaces between resin cement and etched ceramic were examined with FE-SEM. RESULTS: FE-SEM results showed that etching with HFA resulted in preferential dissolution of glass ceramic, and partially supported crystals within the glass matrix were lost with the increasing of etching time.FE-SEM indicated that resin cement sealed the cracks and defects and bonded tightly to etched ceramic surface. The mean flexural strength values of group 0, 20, 40, 60 and 120 s were (384 ± 33), (347 ± 43), (330 ± 53), (327 ± 67) , and (317 ± 41) MPa respectively. The mean flexural strength of each group except group 0 s increased significantly to (420 ± 31), (435 ± 50), (400 ± 39), and (412 ± 58) MPa respectively after the application of resin cement. CONCLUSIONS: Overtime HFA etching could have a wakening effect on IPS e.max® Press glass-ceramic. The application of dual-curing resin cement can compensate the strength loss of the etched glass ceramic.

[Technological experience of occlusal reconstruction with IPS e.max Press for severely worn dentition].

PURPOSE: To investigate the feasibility of occlusal reconstruction with IPS e.max Press for patients suffering from severely worn dentition, and to summarize the technological experience. METHODS: IPS e.max Press was used to reconstruct occlusion for one patient with severely worn dentition. Provisional restorations were fitted in worn teeth to rehabilitate the vertical dimension and centric relationship almost 3 months before final treatment. Face bow was used to transfer the general information of provisional restorations to articulator, including the plane of occlusion, anatomical outline and intercuspal position of teeth. RESULTS: After 24 months of follow-up, the masticatory efficiency and facial appearance were improved significantly, and TMJ disorder was not observed. The patient was satisfied with the prostheses. CONCLUSIONS: IPS e.max Press is an effective and reliable treatment of occlusal reconstruction.The short term effect is promoting. Supported by Clinical Medical Research Fund of Bureau of Science and Technology, Jiangsu Province(SBL201230169).

[The prefabricated post and composite resin core technique used in restoring residual crown of posterior tooth].

PURPOSE: To investigate the clinical effect of repairing posterior residual crown using titanium alloy post combined with composite resin core technique. METHODS: Twenty-one patients (26 residual crown) with perfect root canal therapy were selected. Modern bonding technique was used to build up the core with titanium alloy post and flow composite resin together for crown restoration. RESULTS: After ten years of clinical observation, only 4 cases among the 21 patients failed in restoration. The rate of success was 85%. X-ray showed that the periapical alveolar bone density was enhanced after restoration. CONCLUSIONS: Standard root canal therapy and effective post-core strengthening can restore the function of the residual crown and retain the tooth.

[Effect of sintering gold paste coating on the bonding strength of pure titanium and three low-fusing porcelains].

OBJECTIVE: To study the effect of sintering gold paste coating of pure titanium on the adhesion of three porcelains following the protocol ISO 9693, and to investigate the titanium-porcelains interfaces. METHODS: Sixty machined pure titanium samples were prepared in a rectangular shape according to ISO 9693 and divided equally into six groups. Half of the strips were coated with gold paste (Deckgold) and sintered. Three ultra-low-fusing dental porcelains (I: Initial Ti, S: Super porcelain Ti-22, T: TitanKeramik) were fused onto the titanium surfaces. A thin layer of bonding agent was only applied on the surfaces of uncoated gold specimens. The interface of the porcelain and titanium was observed with a field emission scanning electron microscope (FE-SEM) after metallographic preparation and sputtered with a very thin carbon layer of the embedded titanium-porcelain interface. After three-point bending test was performed, optical stereomicroscope was used to characterize the titanium-porcelains adhesion and determine the mode of failure. RESULTS: FE-SEM illustrated intermetallic compounds of Au-Ti formed with some visible microcracks in the gold layer and the interface of gold layer and ceramic. All the uncoated gold titanium-porcelain system showed predominately adhesive fracture at the titanium oxidation, whereas the failure modes in all gold coated systems were cohesive and adhesive, mainly cohesive. The three-point-bending test showed that the bonding strength of GS and GI groups [(37.08 ± 4.32) and (36.20 ± 2.40) MPa] were higher than those in uncoated groups [(31.56 ± 3.74) and (30.88 ± 2.60) MPa, P < 0.05], while no significant difference was found between T group and GT group (P > 0.05). CONCLUSIONS: The gold paste intermediate coatings can improve bond strengths of Super porcelain Ti-22 system and Initial Ti system, which have potential applications in clinical fields.

[Esthetic restoration for anterior teeth with the hot pressed porcelain laminate veneers].

PURPOSE: To evaluate the esthetic effect of anterior porcelain veneers fabricated with the heat pressed glass ceramic. METHODS: Thirty-two patients, who wanted to receive a aesthetic restorative treatment for 206 anterior teeth were selected. Among them, 20 were for dental fluorosis, 8 were for light tetracycline stained teeth, the other 4 were labial enamel hypoplasia or obvious crack on the surface of enamel. According to the color of adjacent teeth,skin and lips, heat pressed IPS e.max ingots of different color were chosen to mold the restorations. Afterwards, special straining technique was conducted on the marginal ridge and incisor ridge of the veneers after carefully trimmed in the mouth. Restorations were them bonded with Variolink II resin cement. After 7 years of follow-up, a modified USPHS criterion was used to evaluate the esthetic effect. RESULTS: The translucency of veneers was superior. Marginal integrity of the veneers was perfect and it docked well with the marginal terminate line of the abutment. There was no edge coloring after the veneers were used for 7 years, and the veneers produce an excellent chameleon effect by absorbing the color of adjacent teeth and gums, at the same time, veneers could produce a feature of surface morphology of natural enamel after careful carve. In the long-term clinical observation, 5 of the 206 veneers were fractured or fell off. CONCLUSIONS: This porcelain laminate veneers fabricated from the heat pressed IPS e.max Press ingots include the following advantages, such as simple operating procedure, high mechanical strength, very little dental tissue was ground off and nice aesthetic effect. Ultra-thin veneers are especially suitable for aesthetic practice to dental fluorosis, light tetracycline and natural worn teeth.

[The comparative research on resin bond strength and durability of two machinable glass ceramic].

OBJECTIVE: To evaluate the effect of different silane couplers on bond strength and durability of two machinable glass ceramics to resin cement. METHODS: Two machinable glass ceramics (A and B) were silanized by three silane couplers (A, B, C), and were bonded with a resin cement (G-CEM) to form micro-shear test specimens of six groups. The specimens of each group were subdivided into two subgroups, and their micro-shear bond strength was measured before and after 10000 thermal cycles. Bond strength data were analyzed by two-way ANOVA. RESULTS: Before thermal cycles, the bond strength of ceramic A treated by silane coupler A was lower than that of ceramic B (P = 0.002). The bond strength of ceramic A treated by silane coupler C was significantly higher than that treated by silane coupler A and B (P = 0.014, P = 0.019). 10 000 thermal cycles obviously decreased the bond strength of all groups except the group of ceramic A treated by silane coupler B, and no significant difference was found between three silane coupler with either of two ceramic. However the bond strength of ceramic B treated by silane coupler B and C was significantly higher than that of ceramic A (P = 0.003, P = 0.027). CONCLUSION: As well as the types of silane coupler, the type of ceramic could affect their bond strength and durability to resin cement.

[Clinical evaluation of zirconia all-ceramic crowns and bridges designed and manufactured by computer aided design and computer aided manufacture system].

OBJECTIVE: To evaluate the clinical behavior of zirconia restorations fabricated by computer aided design and computer aided manufacture (CAD-CAM) system. METHODS: One hundred and thirteen patients with 167 unit restorations were enrolled in the study. First, the shape of abutment teeth and occlusion record was captured and digitized by Sirona inEos system. Then, each individually shaped framework was created using the cut-back program of inLab V3.85 software to leave a uniform thickness to the ceramic veneer. All restorations were veneered with Vita-VM9 and evaluated at baseline, 6, 12 months after delivery using the modified U S Public Health Service Criteria (USPHS). RESULTS: During the 6 to 12 months' follow-up visit, the success rate of the restorations was 96.1% (147/153), none was replaced due to framework fracture or unrestorable delamination of the ceramic veneer, and all patients were satisfied with the shape and color of their restorations. CONCLUSIONS: Based on the results of this study, it can be concluded that zirconia frameworks demonstrated sufficient stability for all-ceramic fixed partial denture using individual-design processing technology.

[Bond durability of self-adhesive resin cement to glass ceramic].

OBJECTIVE: To evaluate the bond durability of glass ceramic to self-adhesive and conventional resin cements. METHODS: Maximum water sorption and solubility of two resin cements (A: self-adhesive type, G-CEM; B: conventional type, Linkmax HV) were measured during 6 week water storage. And their surface Knoop hardness number was measured at 0.5, 24 h and 6 week after irradiation. Sixty-four glass ceramic samples were or were not silanized with one of the three silane coupling agents (A: Monobond S; B: Clearfil Ceramic Primer; C: GC Ceramic Primer), and then cemented with two resin cements. The micro-bond strength between the two cements and glass ceramic were measured at baseline and after 30 000 thermal cycle. RESULTS: Cement A had higher water sorption [(79.62 +/- 5.63) microg/mm³] and solubility [(4.78 +/- 3.33) microg/mm³] than cement B[(35.03 +/- 3.33) microg/mm³, (0.00 +/- 0.00) microg/mm³]. Cement A and B could achieve maximal surface hardness at 24 h after irradiation, and this was maintained during 6 week water storage. After 30 000 thermal cycle, the micro-bond strength between unsilanized glass ceramic and cement A or B was (0.00 +/- 0.00) MPa, and those between cement A and silanized glass ceramic with silane coupling agent A, B and C, were (2.86 +/- 3.25), (12.75 +/- 1.55) and (11.98 +/- 2.35) MPa respectively [for cement B, the data was (5.15 +/- 5.20), (10.94 +/- 3.30) and (14.18 +/- 3.13) MPa]. No significant diffrence was found between the micro-bond strength of cement A and that of cement B with glass ceramic. CONCLUSIONS: Self-adhesive resin cement can achieve similar bond durability to glass ceramic as conventional resin cement does.

[Effect of hydrofluoric acid etching time on the resin bond durability of glass ceramic].

OBJECTIVE: To analyze the effect of hydrofluoric acid (HFA) etching time on the resin bond durability of glass ceramic. METHODS: Three groups of samples of machinable glass ceramic (ProCAD) were etched by 4.8% HFA for 0, 30 and 60 s respectively. The roughness parameters (Ra, Sm, S) and surface area of the samples, were measured with a 3D-laser scanning microscope. Then the ceramic surfaces were bonded with four resin cements (silane coupler/resin cement), which were Monobond S/Variolink II, Clearfil Ceramic Primer/Clearfil Esthetic Cement, GC Ceramic Primer/Linkmax HV, and Porcelain Liner M/SuperBond. The micro-bond strengths between the ceramic and the resin were tested at baseline and after the samples had been treated in 30000 thermal cycles. RESULTS: The Ra [(3.89+/-1.94), (12.53+/-0.80), (13.58+/-1.10) microm] and surface area [(7.81+/-2.96), (30.18+/-2.05), (34.16+/-1.97) mm2] of ceramic increased with the increase of HFA etching time. The thermal cycling test reduced the bond strength of all test groups. The bond strength of Monobond S/Variolink II group [(3.59+/-3.51), (16.18+/-2.62), (20.33+/-2.45) MPa] and Clearfil Ceramic Primer/Clearfil Esthetic Cement group [(4.74+/-2.08), (7.77+/-1.55), (13.45+/-3.75) MPa] increased with the increase of HFA etching time; 30 s HFA etching group of Porcelain Liner M/SuperBond had higher bond strength [(22.00+/-1.64) MPa] than its 0 s HFA etching group [(12.96+/-4.17) MPa], and no significant difference was found between the 30 s and 60 s HFA etching groups of Porcelain Liner M/SuperBond [(20.42+/-3.01) MPa]. HFA etching time had no effect on the bond strength of GC Ceramic Primer/Linkmax HV. CONCLUSIONS: HFA etching can improve the resin bond durability of glass ceramic, and the etching time is not only related to the change of ceramic surface roughness and area, but also to the characteristics of resins.

[Detection and monitoring of enamel early caries in vivo using red fluorescence analysis by quantitative light-induced fluorescence method].

OBJECTIVE: To study the effects of two primers on the bond strengths between casting pure titanium and resin cements. METHODS: Two sizes of specimen were fabricated by casting, which diameter were 4 mm and 5 mm respectively, and then were cut into 3 mm thick titanium discs. The titanium surfaces were polished with silicon carbide sand papers under running water and then treated by sandblasting. The two size of titanium discs were ultrasonic cleaned and treated with Alloy Primer, V-Primer or without primer, and then bonded in pairs with the resin-based cements Super-Bond C&B, Panavia F and Rely X Unicem. The specimens were then stored in distilled water (37 degrees C) for 24 h. Bond strengths were determined before and after 5 000 thermocycling. The titanium surface morphous and failure mode of the teat specimen were observed. RESULTS: The shear bond strengths of titanium treated by Alloy Primer to Super-Bond C&B were (31.23 +/- 4.86), (34.08 +/- 3.36) MPa before and after 5 000 thermocycling, which higher than that of other combinations of primers and resin cements. CONCLUSION: Bond strengths were influenced by primers, resin cements, and their combinations. The highest bond strengths were the combinations of Alloy Primer and Super-Bond C&B.

[Research on the resin bond durability of glass-infiltrated alumina ceramic].

OBJECTIVE: To analyze the effect of different silane coupling agents on the resin bond durability of glass-infiltrated alumina ceramic. Methods A glass-infiltrated alumina ceramic was silanized or not by three silane coupling agents. The treated ceramic surfaces were bonded with two resin cements. Their micro-bond strength were measured after 0, 30,000 thermal cycles. RESULTS: Before thermal cycling, resin cement A had lowest bond strength to ceramic, and ceramic treated by silane coupling agent A with two cements had lower bond strength than those treated by silane coupling agent B and C. After thermal cycling, cement A had no bond strength with no treated ceramic, only ceramic treated by silane coupling agent A with two cements had more than 5 MPa bond strength. CONCLUSION: The glass-infiltrated alumina cermaic treated by the silane coupling agent activated by 10-methacryloyloxydecyl-dihydrogen phosphate could obtain better bond durability with different type of resin cements.

[Effect of irradiation intensity on dual-cured resin/ceramic bond durability].

OBJECTIVE: To evaluate the effect of light irradiation intensity on bond durability of dual-cured resin luting agents to silanized ceramics. METHODS: Linkmax HV (LMHV), Nexus 2 (NX2), Variolink II HV (VL II HV) as dual-cured resin luting agents were bonded to silanized GN-I glass ceramics, and irradiated by 800, 310 and 80 mW x cm(-2) light intensity to form micro-shear test specimens. After 1, 90 d water storage, micro-shear bond strength of silanized resin/ceramic luting agent were measured. Data of each resin luting agent were analyzed by one-way ANOVA. RESULTS: 90 d water storage decreased significantly the bond strength of all test groups, and the weak of irradiation intensity did not deteriorate this reduction of bond strength of luting resin/cermaic, oppositely in which LMHV irradiated by 310 mW x cm(-2) light intensity and NX2 irradiated by 80 mW x cm(-2) showed the higher bond strength than that irradiated by 800 mW x cm(-2). CONCLUSION: The weak of irradiation intensity does not affect the bond durability of dual-cured resin luting agents to silanized ceramics.

[Effect of Ti bonder on the bond strength between porcelain and titanium].

OBJECTIVE: To investigate the influence of GC Initial Ti Bonder on bond strength between Vita Titankeramik porcelain and titanium. METHODS: Forty titanium samples were prepared and randomly assigned to 4 groups with 10 samples in each group. Samples in each group were subjected to one of the following surface treatments, burnishing (Group B), sandblasting (Group S), firing GC Initial Ti Bonder after burnishing (Group BG) and firing GC Initial Ti Bonder after sandblasting (Group SG). Vita Titankeramik porcelain were fired on the surface of each sample in the middle. Three-point bending tests were conducted on each sample according to the ISO 9693. The fracture patterns of all specimens were recorded using zoom stereo microscope (ZSM) and the fracture surfaces were observed under scanning electron microscope (SEM). RESULTS: With fired GC Initial Ti Bonder, the bond strength of Vita Titankeramik porcelain to titanium in Group BG and Group SG were (32.72 +/- 4.46) and (34.25 +/- 6.52) MPa respectively, which reach the ISO 9693 standard for clinical use and were significantly higher than those in Group B [(20.70 +/- 3.15) MPa] and Group S [(23.92 +/- 5.02) MPa]. CONCLUSIONS: GC Initial Ti Bonder can significantly improve bond strength between Vita Titankeramik porcelain and titanium.

[A comparison of color space of Vitapan 3D-Master shade guides to nature teeth from Nanjing population].

OBJECTIVE: To study the fitness of color dimension between Vitapan 3D-Master shade guides and nature teeth. METHODS: 2,159 nature teeth from Nanjing population and Vitapan 3D-Master shade guides were analyzed by dental chromameter ShadeEye NCC on CIE L*a*b* color system. RESULTS: 1) The color dimension of natural teeth displayed a broader range than those from Vitapan 3D-Master shade guides. Comparing with incisor group, canine-premolar group had better fitness with Vitapan 3D-Master shade guides. 2) In color space, incisor values a* shifted toward green (-a*), while the shade guide values a* located toward red (+a*). The shade guide lacked tabs of values L* 71-78 and a* -1.5-(-)0.2 for natural incisor. 3) According to the perceptibility threshold AE*ab<1.4, the match rates with Vitapan 3D-Master shade guides was 33% in incisor group and 50% in canine-premolar group. CONCLUSION: Vitapan 3D-Master shade guides had inferior match with nature teeth from Nanjing population, especially in incisor.

[Comparison of shear bond strength of different resin cements to ceramic and dentin].

OBJECTIVE: To evaluate the effect of different resin cements and dentin surface treatment methods on shear bond strength between glass ceramic and human dentin. METHODS: Freshly extracted non-carious human premolars were collected to prepare flat mesial and distal dentin surface with diamond bur. Besides, ceramic discs (3 mm in diameter, 3 mm in height) were fabricated with IPS e. max Press ingots. All samples were randomly divided into five groups, sixteen specimens each. Ceramic discs were cemented on dentin surface using one of the five resin cements [Group A (Variolink II), Group B (Multilink Automix), Group C (Multilink Sprint), Group D (Rely X Unicem) and Group E (BisCem)] respectively. Half of the specimens were stored in water 37 degrees C for 24 h and the other half were additionally thermocycled for 5000 times (5 degrees C/55 degrees C) before shear bond strength test. Dentin bonding surface and transverse plane were examined with a scanning electronic microscope. RESULTS: Group A showed the highest bond strength before thermocycling [(22.3 +/- 3.9) MPa], and the bond strength of Group B [(18.1 +/- 3.5) MPa] was lower than that of Group A (P < 0.05). Group E [(11.7 +/- 4.2) MPa], Group C [(11.3 +/- 3.6) MPa] and Group D [(14.1 +/- 2.3) MPa] had the lowest bond strength. After thermocycling, Group A still showed the highest bond strength [(17.8 +/- 2.3) MPa]. The bond strength of Group B [(14.4 +/- 3.5) MPa] and Group D [(13.2 +/- 2.5) MPa] were lower than that of Group A. Group E [(8.9 +/- 3.2) MPa] and Group C [(7.0 +/- 2.4) MPa] showed the lowest bond strength. The bond strength of all groups decreased notably after thermocycling except Group E and Group D. CONCLUSIONS: The resin cement based on etch-rinsing bonding system has higher bond strength to dentin than those based on self-etch bonding system and self-adhesive resin cements.