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@#Dental bonding technology and materials have been used widely in dentistry because of their excellent properties. The development of novel bonding technology and materials is constantly being performed to improve the effect of dental bonding restorations. Observation and analysis of the dental bonding interface is one of the most important methods for laboratory evaluation of bonding efficiency. This paper aims to review the methods of observation and analysis of dental bonding interfaces to provide a reference for the selection of evaluation methods in dental bonding research. The features of 6 methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Raman spectroscopy (RS), optical coherence tomography (OCT) and atomic force microscopy (AFM), were described and summarized. Among these methods, SEM and TEM are used most often in the analysis of fine structures; CLSM and OCT are used for the acquisition of characteristic image signals, such as microleakage and exogenous and endogenous fluorescence; and RS and AFM can test chemical composition and mechanical properties.
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Objective@#To explore the best indication for veneers and to improve the repair success rate by investigating the effects of different types of dentin exposure on the shear bond strength of cast porcelain veneers with two new veneer bonding systems.@*Methods@#Bonding interfaces with 0%, 25%, 50%, 75% and 100% dentin exposure were designed and fabricated. The bonding interfaces were divided into groups A, B, C, D and E. Sixty 4-mm x 4-mm x 2-mm (length x width x thickness) ceramic specimens were bonded by using two bonding systems, The VN-A, VN-B, VN-C, VN-D and VN-E groups were bonded with Variolink bonding system, and the PF-A, PF-B, PF-C, PF-D and PF-E were bonded with Panavia F bonding system (six specimens per group). The bonded specimens were stored in a distilled water bath at (37 + 1)℃ for 24 hours. The fracture load was tested by a universal testing machine, and the fracture type was observed by scanning electron microscopy.@*Results @#The VN-A (25.14 ± 3.40 MPa), VN-B (22.54 ± 4.48 MPa), VN-C (19.59 ± 2.21 MPa), PF-A (20.61 ± 2.42 MPa), PF-B (18.08 ± 4.11 MPa), PF-C (17.06 ± 2.29 MPa) groups’ shear bond strengths were above 17 MPa. The VN-A group had the highest shear bond strength value. There was no statistically significant difference in bond strength between the VN-A group and the VN-B and VN-C groups (P > 0.05) or the PF-A and PF-B groups (P > 0.05); however, the differences between VN-A and the VN-D and VN-E groups (P < 0.05) and between PF-A and the PF-C and PF-D and PF-E groups (P < 0.05) were statistically significant. The differences between the VN-A group and PF-A group (P < 0.05) were statistically significant. The fracture modes of the VN-A, PF-A, VN-B, PF-B, and VN-C groups mainly included resin cement cohesive failure and mixed failure; the VN-D, VN-E, PF-C, PF-D and PF-E groups were dominated by interface failure and mixed failure.@*Conclusion@#When the dentin exposure is greater than 50%, the shear bond strength value of the veneer was significantly affected. To obtain a better clinical effect, the dentin exposure rate should be less than 25%.
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Objective@#To study the effects of bacterial invasion and artificial saliva immersion on the bond strength and nanoleakage between healthy dentin and glass ceramics-bonded specimens using three types of resin cements and provide a reference for the selection of clinical bonding materials.@*Methods @#One hundred eight dentin blocks were selected to prepare bonded specimens with Variolink N, Multilink N, RelyX Unicem and glass ceramics blocks. The adhesive specimens of each type of resin cements were divided into three groups according to the aging method: bacterial invasiveness group (the specimens were cultured under anaerobic conditions for 14 days after inoculation with Streptococcus mutans), artificial saliva immersion group (the specimens were immersed in artificial saliva for 6 months), and control group (the immediate test group). Each group comprised 12 specimens: 6 were selected to test the bonding strength, and 6 were observed by scanning field emission scanning electron microscopy (FESEM). @*Results @#The bond strength of Variolink N in the immediate test group was significantly higher than that of Multilink N and RelyX Unicem, and the difference was statistically significant (P < 0.05). However, no significant difference was found in the bacterial invasiveness group and artificial saliva immersion group (P > 0.05). In the bacterial invasion group, the difference in the nanoleakage of the three adhesives was statistically significant (P < 0.05), with a trend of Variolink N > Multilink N > RelyX Unicem, and pairwise comparison was statistically significant (P < 0.05). The nanoleakage of the three resin adhesives showed an increasing trend in the bacterial invasion group and artificial saliva group compared with that of the immediate test group. @* Conclusion@#Both artificial saliva soaking and bacterial invasion can reduce the sealing property of the adhesive interface of 3 types of resin cements to different degrees. The presence of Streptococcus mutans in the oral cavity may reduce the sealing performance of the resin dentine adhesive interface.
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Introduction: Nanoleakage evaluation by silver uptake in permanent teeth provides good spatial resolution of submicron defects at the hybrid layer, which have not been tested in primary teeth. Objective: This study evaluated the nanoleakage at the dentin-adhesive interface in primary teeth by two methods, for three adhesive systems, immediately (IM) and six months (6M) after adhesive procedures. Material and methods: Crowns of primary molars were occlusal flat grounded and divided into three groups according to the adhesive system tested (n = 6-7). Scotchbond Multi-purpose/SMP, Single Bond/SB and Clearfil SE Bond/CSB adhesive systems were applied with a composite resin (Filtek Z-250). Crowns were sectioned so that 0.8 mm² sticks were obtained and subdivided depending on the time of evaluation: IM or 6M. They were immersed into silver nitrate solution and evaluated by SEM-EDS. Data (%) were analyzed by ANOVA (p < 0.05) and the scores by Kruskal-Wallis and U Mann-Whitney tests (p < 0.05). Results: There was no difference between groups regarding to the evaluation time (aging) percentage. In terms of scores, there was a significant difference for the adhesive variable: SMP and SB showed similar results with less leakage, while CSB demonstrated higher leakage. Conclusion: Nanoleakage was not influenced by aging, but noticeable difference was observed between total-etch and self-etching adhesives. Total-etch showed better performance.
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Objective: To study the bonding interface characteristic of five wet bonding systems while bonding on different dentin bonding surfaces. Methods: Rhodamine B was used to label five adhesives(OptiBond Sol o,Single Bond,Gluma One-Bond,Bond-1 and One-Step) in consistency of 0.1%, an d the bonding interface of the 5 wet bonding systems on dry or wet dentin surfa ces was observed with laser scanning confocal microscope. Results: All five bonding systems could infiltrate well into dentin bonding interface when bonding on wet dentin surface. The fluorescence confocal images gave eviden ce of the adhesives penetrated into the widened tubules, lateral tubules and dem ineralized peritubular dentin. Little discontinuity in dentin tubular was observ ed in the images, especially in those of alcohol-water-based adhesives. When b onded in dry dentin surface, the hybrid thickness of acetone-based adhesives de creased significantly. Conclusion: The penetration ability of ad hesives may be reduced significantly on dry dentin surface.
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Objective:To compare the shear bond strength of dentin to composite resin in different post-treatment time period after tooth bleaching with the TREE dental whitening gel and observe the dentin/composite interface of each group. Methods:Eighteen intact premolars were randomly divided into 3 groups(n=6):A:The specimens were immersed into artificial saliva for 3 weeks then adhesion without bleaching; B:Adhesion immediately after bleaching for 3 weeks,during bleaching the specimens were immersed into artificial saliva; C:Before adhesion the specimens immersed in artificial saliva for further 2 weeks after bleaching for 3 weeks. Five specimens from each group were randomly submitted to shear bond strength test. The specimen remained in each group were sectioned to be observed by the scanning electron microscope.Results:(1)The shear bond strength of the group B (10.74?3.03) MPa was significantly lower than that of the group A (18.61?3.56) MPa or the group C (17.21?3.15) MPa (P0.05); (2)The resin tags present in the dentin/composite interface was scarce for the group B,and that were shorter than the group A; The resin tags of the group A and group C were similar in number,but that of the group C was shorter than that of the group A. Conclusion:The use of TREE whitening gel immediately before bonding significantly reduces bond strength,but immersion of bleached teeth in artificial saliva for 2 weeks before bonding results in a return to control bond strength.
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Objective: To study the effect of Carisolv in caries removal on dentin bonding surface.Methods:24 extracted third molars with moderate carious were randomly divided into four groups. Each cavity was split into two parts, one part was prepared by Carisolv and the other by high-speed bur. Then samples were processed as follows: samples in group A were not treated, those in group B were treated with 320 ml/L phosphoric acid, SEM was used to observe the morphology of dentin surface of the samples in group A and B. Samples in group C were restored with Dyract AP and those in group D with resin for the observation of the microstructure of dentin-filling bonding interfaces.Results:In group A, rough surface without obvious smear layer was exhibited and dentinal tubules were clearly open after Carisolv preparation; after bur preparation, dentin surfaces were covered with a thick smear layer and no opening of tubules was visible. In group B, after treatment with 320 ml/L phosphoric acid, the smear layer was removed and dentinal tubules were exposed after either Carisolv or bur preparation, but tube stoppers were visible in the samples prepared by bur. In group C, resin tags were observed only in the samples after Carisolv preparation. In group D,dentin surfaces and lengths of the resin tags did not show remarkable difference after Carisolv or bur preparation, but more lateral branch connection between resin tags appeared in the samples prepared by Carisolv than by bur.Conclusion:The dentin prepared by Carisolv favors bonding between dentin and resin/compomer and has the advantage of restoring with compomer.
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Objective:To evaluate the characteristics of bonding interface and microstructure of different resin composite inlays. Methods:Different composite resins and adhesives were used for restoration of extracted molars, the results were evaluated under scanning electron microscope(SEM) and atomic force microscope(AFM).Results:The microstructure feature of Tescera was with higher density when compared with that of other conventional resins,and fewer small holes could be seen in Tescera. AFM pictures showed that Tescera was with a very smooth surface. Indirect composite resin could be combined with resin bonding agent tightly and infiltrated each other. The interface between direct resin inlay material and resin bonding agent was very clear,and no obvious interfiltration could be seen under SEM and AFM. Conclusion:After treatment with water, heat,light and pressure, the physical properties of indirect composite resin is improved effectively, and obvious infiltration can be found in the interface.
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Objective:To observe the microstructure of interface between material and dentin after root canal rehabilitation. Methods:Three human maxillary incisors extracted within one week were used. After crowns being removed and received root canal treatment, they were used for the study. The root was split into two parts along the long axis, then the bonding interface was made with high speed diamond bur. Bis-Core and Chemil Superior glass-ionomer were stacked on root canal inner wall respectively and the teeth were split along with the long axis with Isomet saw, in order to expose bonding interface. The microstructure of bonding interface of the samples were analyzed by optical microscope and atomic force microscope(AFM). Results: AFM observation of the adhesive interface specimens showed that Chemil Superior glass-ionomer and teeth knitted together completely and no filling invaded into dentin tube. While the bonding interface between Bis-Core and dentin, dentin primer infiltrated into dentin tube and matrix around through the smear layer and colophony protruded. Conclusion:The observations reveal the extent of resin penetration into the dentinal tubules provides a very strong bonding. This is a fundamental cause of resin better bond to tooth.