Dentin Group Research Articles

Dentin Conditioning Using Different Laser Prototypes (Er,Cr:YSGG; Er:YAG) on Bond Assessment of Resinmodified Glass Ionomer Cement

The aim of this study was to evaluate and compare various conditioning regimes (laser and conventional) on shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) bonded to dentin. Sixty non-carious intact maxillary molars were cleaned, isolated, and randomly divided into six groups (n = 10). Before randomization, the dentin surface was exposed and finished. Samples in group I were conditioned using Er,Cr:YSGG laser (ECYL). Specimens in group II were conditioned using Er:YAG laser (EYL), and the dentin surfaces of specimens in group III and group IV were conditioned using cavity conditioner and K930. Similarly, the samples in group V and group VI were surface treated using 17% EDTA and total etch. All samples were bonded with RMGIC following conditioning regime. For SBS testing, the samples were placed in universal testing machine. A fracture analysis of debonded surfaces was evaluated using stereomicroscope at 40× magnification. Means and standard deviations (SDs) were calculated using analysis of variance (ANOVA) and Tukey's post hoc test at a significant level of p < 0.05. The maximum bond strength values were observed in group VI total etch (23.85 ± 3.67). The lowest bond strength was displayed in laser dentin group II conditioned by EYL (11.65 ± 2.77). Dentin conditioned with ECYL, cavity conditioner, K930 conditioner, and 17% ethylenediaminetetraacetic acid (EDTA) were found to be comparable, p > 0.05. Cohesive failure was dominant among experimental groups. Er,Cr:YSGG laser has a potential to be recommended for dentin conditioning prior to application of RMGIC. Dentin conditioning enhances adhesion of RMGIC for improved prognosis and treatment outcome.

Potential of Treated Dentin Matrix Xenograft for Dentin-Pulp Tissue Engineering

IntroductionThis study aims to develop and characterize the regenerative potential of an atelopeptidized treated dentin matrix xenograft using in vitro and in vivo models. MethodsFreshly extracted bovine dentin was pulverized into 250- to 500-μm particles and demineralized with 17% EDTA for 1, 7, and 13 days. The samples were atelopeptidized with pepsin. The degree of demineralization and the effect of atelopeptidization were assessed using field emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, respectively. The expression of dentin matrix acidic phosphoprotein 1, dentin sialophosphoprotein, and osteopontin was evaluated in dental pulp stem cells using quantitative real-time polymerase chain reaction. The samples were then implanted intramuscularly in rats for 30 days, and the inflammatory cells were quantified histologically. ResultsField emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy revealed an exposed tubular structure of dentin after 1 and 7 days of demineralization. Fourier transform infrared spectroscopy confirmed the absence of amide peaks at 1260 to 1640/cm after atelopeptidization. The dental pulp stem cell expression of dentin matrix acidic phosphoprotein 1 and dentin sialophosphoprotein increased in all compared with the untreated control group (P < .05). The maximum expression rates were observed for the 1-day demineralized and atelopeptidized group. The 1-day demineralized group elicited the highest inflammatory response compared with the 7- or 13-day demineralized groups (P < .001). Atelopeptidization significantly decreased the inflammatory response only in the 1-day demineralized dentin group (P < .05). ConclusionsAtelopeptidization of 1-day demineralized dentin xenograft preserved the collagen structure, minimized the immune reaction, and provided sufficient regenerative potential.

Autogenous Dentin Shell Grafts Versus Bone Shell Grafts for Alveolar Ridge Reconstruction: A Novel Technique with Preliminary Results of a Prospective Clinical Study.

This prospective pilot study presents a novel method using the dentin shell technique for the three-dimensional reconstruction of alveolar bone defects. Autogenous dentin shell (≤ 2 mm) harvested from impacted third molars was fixed at the recipient site as an external barrier. The space between the dentin shell and residual bone was filled with deproteinized bovine bone mineral particles mixed with concentrated growth factor (CGF) pieces. Autogenous bone (gold standard for bone graft) was applied to prepare shell grafts as the control. A total of 13 patients were included in the study and received bone reconstruction with the dentin shell technique (dentin group, n = 7) or bone shell technique (bone group, n = 6), respectively. At 24 weeks postsurgery, cone beam computed tomography results showed no statistically significant difference between the two groups regarding vertical bone gain and vertical and horizontal bone resorption. Histologic and microcomputed tomography analyses revealed significant newly formed bone connecting directly to the resorbed dentin shells. The dentin shell technique restored bone volume successfully without major complications.

A comparative study of the microtensile bond strength and microstructural differences between sclerotic and Normal dentine after surface pretreatment

BackgroundThe resin bond strength of sclerotic dentine is significantly lower than that of the normal dentine, which paused a challenge for bonding procedures clinically. The aim of this study was to compare the effects of different surface pretreatments on the micro-tensile bond strength and microstructure between sclerotic dentine and normal dentine.MethodsEighty teeth that were collected, forty premolars with typical wedge-shaped defects visually graded as class III were assigned as the sclerotic dentine group (SD), the other forty normal premolars with artificial wedge-shaped defects were assigned as the normal dentine group (ND). Each group was randomly subdivided into eight subgroups according to the solution used: 35% phosphoric acid, 15% EDTA, 5% or 10% NaClO. Then the dentine surface was examined using a scanning electron microscope (SEM). The lesions were restored using self-etching adhesive and the subsequent resin composite. The teeth were sectioned into sticks for the micro-tensile bond strength analysis, and the data were analysed using the SPSS17.0 software package (α = 0.05).ResultsFirst, for the ND groups, after pretreatment using 35% phosphoric acid, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the normal dentine were higher than that of the other groups (P < 0.05). Second, for the SD groups, after pretreatment using 35% phosphoric acid, 15% EDTA, and 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the other groups (P < 0.05). Third, the bond strengths of the sclerotic dentine were lower than that of the normal dentine without any pretreatment (P < 0.05). After pretreatment using 35% phosphoric acid + 5% or 10% sodium hypochlorite, the bonding strengths of the sclerotic dentine were higher than that of the normal dentine (P < 0.05). SEM observation showed that the appearances of dentine surface were changed after pretreatment using the above solutions, with the reduced smear layer, opened small groove and increased dentinal tubules.ConclusionPretreatment of dentine using 35% phosphoric acid+ 5% or + 10% sodium hypochlorite changed the microstructure of the sclerotic dentine surface and subsequently increased the micro-tensile bond strength.

Influence of bonding surface and bonding methods on the fracture resistance and survival rate of full-coverage occlusal veneers made from lithium disilicate ceramic after cyclic loading

ObjectivesThe purpose of this laboratory study was to evaluate the influence of bonding method and type of dental bonding surface on fracture resistance and survival rate of resin bonded occlusal veneers made from lithium disilicate ceramic after cyclic loading. MethodsFourty-eight extracted molars were divided into three groups (N=16) depending on the preparation: within enamel, within dentin/enamel or within enamel/composite resin filling. Lithium disilicate occlussal veneers were fabricated with a fissure-cusp thickness of 0.3–0.6mm. Restorations were etched (5% HF), silanated and adhesively luted using a dual-curing luting composite resin. Test groups were divided into two subgroups, one using a only a self-etching primer, the other additionally etching the enamel with phosphoric acid. After water storage (37°C; 21d) and thermocycling (7500 cycles; 5–55°C), specimens were subjected to dynamic loading in a chewing simulator (600,000 cycles; 10kg/2Hz). Surviving specimens were loaded until fracture using a universal testing machine. ResultsAll specimens survived artificial aging, several specimens showed some damage. ANOVA revealed that enamel etching provided statistically significantly (p≤0.05) higher fracture resistance than self-etching when bonding to enamel and dentin. Self-etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel-composite group than for the enamel group. Enamel etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel and dentin group than for groups enamel and enamel-composite. SignificanceEtching enamel improved the fracture resistance of occlusal veneers when bonding to dentin and enamel and increased the survival rate when bonding to enamel.

Impact of infected and noninfected human dentine debris on bone healing in rats.

To evaluate in vivo the bone tissue response of rats to varying amounts of infected and noninfected dentine debris. Bone tissue reactions were evaluated histologically in 42 Wistar rats after 7, 30 and 60days. For each animal, three surgical cavities were prepared on the femur and filled with varying amounts (5, 10 or 20mg) of infected or noninfected dentine debris pellets. In the negative control group, the surgical cavities were not filled. At the end of each experimental period, theanimals were euthanized. The samples were processed histologically and analysed using a light microscope. The presence and the severity of inflammatory reaction, as well as hard tissue deposition were evaluated. Data were subjected to statistical analysis and theeffects of the dependent variables calculated using nonparametric tests Kruskal-Wallis and Mann-Whitney U with due Bonferroni corrections at P=0.05. At 7days, the presence of infected debris significantly increased the histopathological scores for neutrophils (P<0.05), and abscess formation (P<0.05). Noninfected debris scored significantly higher for lymphocyte infiltrate compared with the control group and infected debris (P<0.05). Both infected and noninfected debris equally triggered eosinophil cells compared with no-dentine (P<0.05). As for giant cells and macrophages, no difference was detected amongst the dentine groups (P>0.05). Hard tissue deposition was similar regardless of the presence or the bacteriological status of the dentine (P=1.00). None of the above histopathological parameters was significantly influenced by the amount of debris (P>0.05). For all parameters evaluated, at 7days of analysis, the inflammatory response was significantly more intense compared with 30 and 60days (P<0.05). Inflammatory parameters were scored similarly for the evaluated groups after 30 and 60days (P>0.05). However, hard tissue deposition has significantly increased after 30days (P<0.05). No difference was seen between 30 and 60days of analysis (P=1.00) for all histological parameters evaluated. The assumption that the amount of extruded debris may negatively affect the inflammatory response of bone tissue was not validated in the present in vivo animal study. Infected dentine may trigger acute inflammatory parameters especially during the first 7days of contact with the tissue; however, in the long term, these negative effects are mitigated.

Microhardness Investigation of Dental Composite Resins Exposed to Corrosive Environment

The aim of this study was to evaluate the microhardness Rockwell and Young s modulus of a new nano-hybrid and nano-fill composite resins exposed to corrosive media. The study was performed on two composite resins, one nano-hybrid and one nano-fill, enamel, dentine, translucent, respectively body shade, of which were made 20 samples (25.0 � 0.1 mm lengths, 10.0 � 0.1 mm widths and 3.0 � 0.1 mm thicknesses), which were immersed in mouthwash for 1 minute per day for 10 days, the rest of the time being stored in artificial saliva. Measurements of Rockwell microhardness and Young�s modulus on samples were made between on the first day, after 6 days and 10 days of immersion in mouthwash comparative with 0 day. The results showed that after immersion in the corrosive environment, both materials had the hardness values changed, but medium values of Rockwell microhardness to nano-fill composite resin were higher than nano-hybride. At the nano-hybride composite resin, it was observed that the enamel and clear translucent groups had the mean values increased after the first day of exposure to mouthwash, compared to the dentine group, which showed a higher mean value after 6 days. At the nano-fill composite resin, for the enamel and body groups were obtained the higher values of HRC after 10 days. For the dentine group, after 6 days, Filtek Ultimate showed the same variation as Harmonize dentine shade. Harmonize composite resin showed higher values of Rockwell microhardness and Young�s modulus for all study groups compared to Filtek Ultimate.

EVALUATION OF SHEAR BOND STRENGTH OF COMPOSITE TO DENTIN REWETTED WITH A DESENSITIZER- AN IN-VITRO STUDY

Aim: The aim of the study was to evaluate the shear bond strength of composite to dentin with 2 different dentin bonding agents after dry dentin is rewetted with a desensitizer.&#x0D; Materials and Methods: Sixty human mandibular molars were taken and the occlusal surface was ground to expose flat dentinal surface. The samples were divided into two major groups Group I and Group II based on the bonding agent used. In Group I Gluma Bond5 was used and in Group II Adper Single Bond 2 was used. Each major group is subdivided into three subgroups a, b and c with ten samples each. Sub Group ‘a’ is moist dentin group. Sub Group ‘b’ is dry dentin group, Sub Group ‘c’ is rewetted dentin group. The desensitizer used is GLUMA Desensitizer. All these samples were thermocycled and the shear bond test was performed using Instron Universal Testing Machine.&#x0D; Results: Dry dentin rewetted with GLUMA Desensitizer followed by GLUMA Bond5 showed highest shear bond strength than that of other subgroups. The data was analysed using ANOVA and Tukeys honestly significant test.&#x0D; Conclusion: Desensitizer used as a rewetting agent increases the shear bond strength of composite on dry dentin.&#x0D; Keywords: Glutaraldehyde, rewetting.

Bond Strength of Resin Cements Fixing Fiber Posts to Human and Bovine Teeth of Different Ages.

To evaluate the effect of human and bovine root dentin age on the bond strength of fiber posts fixed with resin cements. The degree of conversion (DC) of the resin cements in different root thirds also was evaluated. Ninety-six single-rooted teeth were divided into groups according to the origin and age: young human (20-30 years), old human (over 60 years), young bovine (24-36 months) and adult bovine (over 48 months). The teeth were endodontically treated, and fiber posts were cemented with resin cements (RelyX Ultimate and RelyX U200). After 24 h, the teeth were sectioned perpendicularly and the push-out test was performed in a universal testing machine at a speed of 0.5 mm/min, until failure. One specimen from each third from each group (n = 6) was selected, and the DC of the resin cements was analyzed by FT-Raman spectroscopy. For both resin cements, the young human root dentin group presented the highest bond strengths and the old human root dentin group presented the lowest (p < 0.05). The bond strengths of bovine root dentin groups were not affected by aging (p > 0.05). For the DC of resin cements, there were differences among the root thirds (p < 0.05), with the lowest values observed in the apical third. The bond strengths were higher in the young human root canal than in the bovine substrate, with a negative effect of aging in the human substrate. The DC of dual-curing resin cements decreased from the coronal to apical root thirds.

Effect of Dentin Preparation Mode on the Bond Strength Between Human Dentin and Different Resin Cements.

The aim was to evaluate the influence of different dentin preparation mode in the smear layer characteristics (SL), hybrid layer (HL), and microtensile bond strength (µTBS) to dentin with two resin cements. The occlusal dentin of 120 third molars was exposed. The teeth were divided into 4 groups (n=30) according to the dentin preparation mode: 1- fine grain diamond bur; 2- coarse grain diamond bur; 3- multi laminate carbide steel bur; and, 4- ultrasonic CV Dentus diamond bur. Each treated dentin group was divided into 2 sub-groups (n=15) according to the resin cement: (1) RelyX U200 and (2) RelyX ARC. Resin composite blocks were cemented on dentin. After storage at 37o C for 24 h, beams with a cross section area of 1.0 mm2 were obtained, and tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Two additional teeth for each sub-group were prepared to analyze the SL and HL on a scanning electron microscopy. According to Kruskal-Wallis test and Dunn tests, there was no significant difference in µTBS among the rotary instruments within each resin cement group. RelyX ARC obtained higher µTBS values compared to RelyX U200 (p<0.05). RelyX ARC formed evident HL, which was not observed for RelyX U200. The dentin mode preparation did not influence the µTBS of the resin cements. The SL was different for all instruments. The cementing agent is more determinant in the hybrid layer formation and bond strength to dentin than the instruments applied on dentin.

Effect of Silver Nanoparticles, Zinc Oxide Nanoparticles and Titanium Dioxide Nanoparticles on Microshear Bond Strength to Enamel and Dentin

This study was aimed to evaluate whether antibacterial pretreatment of enamel and dentin with silver nanoparticles (SNPs), zinc oxide nanoparticles (ZNPs) and titanium dioxide nanoparticles (TNPs) has any effect on the microshear bond strength of an etch-and-rinse adhesive system. Eighty human third molars were randomly assigned to eight subgroups (n = 10). Enamel groups included no pretreatment (E), pretreatments with SNPs (ESNP), ZNPs (EZNP) and TNPs (ETNP) before acid etching and adhesive application. Dentinal groups included no pretreat-ment (D), pretreatments with SNPs (DSNP), ZNPs (DZNP) and TNPs (DTNP). The specimens were bonded by Adper Single Bond and polyvinyl chloride microtubes and were restored with Z250 composite. The bonded surfaces underwent microshear bond strength (uSBS) test. Data in megapascal (MPa) were analyzed with the Kruskal-Wallis test and the Mann-Whitney test (p = 0.05). There was not a significant difference among the groups in enamel (p > 0.05). There was no significant difference between the application of three nanoparticles and the control group in dentin. However, DSNPs had a higher uSBS (25.60 ± 14.61) than that of the DZNPs and DTNPs groups (p = 0.03 and p = 0.001, respectively). Also, the mean uSBS value was lower in dentin groups compared to the respective enamel groups (p < 0.05) except for groups DSNPs and ESNPs in which no significant difference was found (p > 0.05). Pretreatment with SNPs, TNPs, and ZNPs can be suggested to achieve potent antibacterial activities without compromising the bond strength. The best result was obtained for pretreatment with SNPs compared to pretreatment with TNPs or ZNPs in dentin and enamel, albeit the differences were not significant in the enamel groups. Effective antibacterial treatment prior to adhesive bonding application is desirable to provide successful restoration if it would not adversely affect the bond strength of the adhesive system. Nanoparticles can be applied to meet this goal.

Microtensile Bond Strength of Polyacid-modified Composite Resin to Irradiated Primary Molars.

This study evaluated the influence of various doses of radiotherapy on the microtensile bond strength (pTBS) of compomer resin to dentin and enamel in primary molars. Thirty-five intact primary molars were collected and divided into seven groups. Teeth were irradiated with doses from 10 to 60 Gy, except for the control group. Compomer restorations were performed, and enamel-compomer resin beams and dentin-compomer resin beams were tested at a crosshead speed of 1 mm/min. No statistically significant difference was found between the irradiated tooth enamel and the control group (F = 1.1468; p = 0.194). However, statistically significant differences were evident among the dentin groups (F = 11.050; p < 0.001). Radiation may not cause a significant difference in the pTBS of compomer resin to primary tooth enamel, but appears to dose dependently decrease its bond strength to primary tooth dentin. Radiotherapy may affect the success rate of compomer fillings in primary teeth, especially in deeper cavities with exposed dentin.

INFLUENCE OF POST-BLEACHING TIME INTERVALS USING 37% CARBAMIDE PEROXIDE ON DENTAL SUBSTRATE ADHESION

The aim of this study was to evaluate the influence of post-bleaching time intervals using 37% carbamide peroxide on dental substrate adhesion. Fifty bovine incisors were sectioned in two groups of 4X4 mm standard blocks to obtain 50 specimens in each group (n=50). In fifty blocks, the dentin (D) was analyzed and in the other 50 the enamel (E). Blocks were subjected to bleaching treatment and restored with Single Bond/z250 according to post-bleaching time intervals (0, 7, 14 and 21 days). Twenty-four hours after adhesive/resin cylinders on substrate confection, shear bond strength test (SBS) was performed in an universal test machine. Means in MPa and their respective standard deviations were: E – control: 31.89 (2.39); T0: 19.07 (2.00); T7: 24.97 (4.89); T14: 29.71 (4.89); T21: 40.91 (4.75) and D – control: 18.90 (3.64); T0: 2.22 (0.41); T7: 3.79 (0.75); T14: 5.95 (0.79); T21: 8.40 (0.87). Data were submitted to ANOVA and Tukey (p&lt; 0.05) tests. The bond strength value for the enamel was statistically higher than the dentin, and both were lower than the control group that had similar results after 21 days post-bleaching. In dentin group, the control showed superior bond strength and was statistically different in relation to other times. It was concluded that bleaching had negative influence on adhesion. Therefore it is necessary to wait, at least, 21 days after bleaching to restore the enamel.

Influence of different smear layers on bond durability of self-etch adhesives

ObjectiveThe purpose of this study was to determine the influence of different smear layers on enamel and dentin bond durability of various types of self-etch adhesives. MethodsTwo universal adhesives, Scotchbond Universal (SU) and Prime & Bond elect (PE); a conventional single-step self-etch adhesive, G-ænial Bond (GB); and two two-step self-etch adhesives, Optibond XTR (OX) and Clearfil SE Bond (SE) were used in this study. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were determined with different smear layer conditions. The prepared specimens were divided into three groups. The bonding surfaces were prepared by grinding with either (1) #180, (2) #600, or (3) #4000-SiC papers before making the bonded assemblies. For each group, 15 specimens were prepared for the SBS and 30 specimens for the SFS. ResultsThe two-step self-etch adhesives showed significantly higher SFS values than the single-step self-etch adhesives, regardless of the smear layer condition or substrate. Although most of the tested adhesives showed no significant differences in enamel SFS values among the smear layer groups, SU, GB, and SE showed significantly lower SFS values in the #180 in dentin groups than the #600 and #4000 groups. ConclusionThe influence of different smear layer conditions on bond durability was adhesive dependent. Furthermore, the smear layers generated on different substrates also influenced the bond quality of the self-etch adhesives. SignificanceSmear layer conditions of enamel and dentin influence the bond durability of universal adhesives and conventional single and two-step self-etch adhesives.

IMPACT OF VARIOUS RESIN ADHESIVE STRATEGIES ON MICRO SHEAR BOND STRENGTH TO SOUND, CARIES- AFFECTED AND REMINERALIZED DENTIN SUBSTRATES: AN IN-VITRO ESEM ANALYSIS

Objectives: The aim of this in vitro study was to evaluate the micro shear bond strength of different adhesive system strategies to sound, artificially caries affected and remineralized dentin substrates.Materials and Methods: Sixty bovine permanent incisors were used. The labial enamel was removed and a flat dentin surface was obtained. The dentin specimens were divided into three main groups (sound as a control, artificial caries affected and remineralized dentin groups). Four adhesive systems were applied over the different dentin substrates according to the directions of the manufacturers; (Futurabond M+, Single bond universal (universal adhesives used in self-etch mode, Futurabond DC (Dual- curing self etch bond with nanofillers and Solobond M (Etch and rinse adhesive). After preparation of the 240 micro tubules of resin composite (Filtek TM Z350XT (Flow able restorative), micro shear bond strength test was performed. The results were tabulated and statistically analyzed. Failure mode was detected for all the fractured dentin specimens using the stereomicroscope. ESEM evaluation was done for resin dentin interfaces for all types of adhesives.Results: There was a statistically significant effect of dentin substrate, while the adhesive system type was not. One way ANOVA followed by Tukey HSD post hoc test showed that, the remineralized dentin recorded the highest micro shear bond strength value with Single Bond Universal followed by Futurabond M+. The artificial caries affected dentin showed the highest micro shear bond strength value with Solobond M followed by Futurabond DC, which also recorded the lowest micro shear bond strength result with remineralized dentin.Conclusions: 1- Performance of the tested adhesives strategies was shown to be dentin-dependant.2- Dentin pretreatment with CPP-ACPF containing paste affects positively the micro-shear bond strength of Single bond universal and Futurabond M+ universal adhesives when used in self-etch mode.3-The specific chemical formula of the tested resin adhesives might coordinate with the demineralized dentin.

Randomized Clinical Trials on Deep Carious Lesions: 5-Year Follow-up

Deep caries presents a dilemma in terms of which treatment that will render an optimal prognosis by maintaining pulp vitality with absence of apical pathology. Previously, 2 randomized clinical trials were performed testing the short-term effects of stepwise carious tissue removal versus nonselective carious removal to hard dentin with or without pulp exposure. The aim of this article was to report the 5-y outcome on these previously treated patients having radiographically well-defined carious lesions extending into the pulpal quarter of the dentin but with a well-defined radiodense zone between the carious lesion and the pulp. In this long-term study, 239 of 314 (76.2%) patients were analyzed. The stepwise removal group had a significantly higher proportion of success (60.2%) at 5-y follow-up compared with the nonselective carious removal to hard dentin group (46.3%) (P = 0.031) when pulp exposures per se were included as failures. Pulp exposure rate was significantly lower in the stepwise carious removal group (21.2% vs. 35.5%; P = 0.014). Irrespective of pulp exposure status, the difference (13.3%) was still significant when sustained pulp vitality without apical radiolucency and unbearable pain was considered (95% confidence interval, 3.1–26.3, P = 0.045). After pulp exposure, only 9% (n = 4) of the analyzed patients were assessed as successful, indicating that the prognosis is highly dubious following conventional pulp-capping procedures (direct pulp capping or partial pulpotomy) in deep carious lesions in adults. In conclusion, the stepwise carious removal group had a significantly higher proportion of pulps with sustained vitality without apical radiolucency versus nonselective carious removal of deep carious lesions in adult teeth at 5-y follow-up (ClinicalTrials.gov NCT00187837 and NCT00187850).

MICROTENSILE BOND STRENGTH AND NANOLEAKAGE OF A RESIN COMPOSITE BONDED TO DENTIN TREATED WITH GALLA CHINENSIS EXTRACT

Aim: This in vitro study aimed to evaluate the effect of dentin surface-treatment with 4mg/ml Galla Chinensis Extract (GCE) on microtensile bond strength and nanoleakage of a resin composite restoration, subjected to two different water storage periods.Materials and Methods: A total of thirty freshly extracted sound human molars were prepared and sliced coronally for application of a nanohybrid resin composite restorative material (Filtek Z350 XT). Exposed dentin surfaces, were acid-etched, to be either routinely covered by adhesive and resin composite, or treated with 4mg/ml Galla Chinensis Extract, followed by application of an adhesive and a resin composite. Treated teeth were divided into 3 subgroups according to time of assessment of their microtensile bond strength and nanoleakage after 24 hours, 3 months and 6 months of water storage.Data were statistically analyzed with One-way ANOVA at 95% confidence interval. Kolmogorov Smirnov and Shapiro-Wilk tests were applied for normality testing. Independent t-test was used to compare between different groups for different water storage periods.Results: Insignificantly different microtensile bond strength values between control and surface-treated teeth were recorded for the resin composite material immediately and after 3 months water storage periods. Lowest values were recorded after 6 months storage period, differing significantly (p ≤0.001) between control and surface-treated dentin group. The immediately tested control group revealed significantly the highest mean microtensile bond strength values (32.1±7.84 MPa) compared to both other control groups at different storage periods. SEM micrographs showed extensive silver deposition throughout the entire hybrid layer thickness of silver-impregnated sections at resin/dentin interfaces after 6 months aging period. These depositions penetrated into dentinal tubules and around the resin tags in the control group.Conclusions: Surface treatment of etched dentin with 4mg/ml Galla Chinensis Extract improved resistance of bonded resin composite restorations to hydrolysis in terms of improved microtensile bond strength and nanoleakage after 3and 6 months of water storage.

The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin.

PURPOSECementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin.MATERIALS AND METHODSNinety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed.RESULTSInitial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001).CONCLUSIONAll resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.

Evaluation of morphological and chemical alterations in enamel, dentin and cementum after internal bleaching technique using different bleaching agents

Objective: The aim of this study was to evaluate the morphological and chemical alterations in enamel, dentin and cementum after internal bleaching using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Material and Methods: Seventy-two bovine incisor teeth were prepared, cut and bleached for 7 days as follows: HP: 35% hydrogen peroxide gel; HP+SP: 35% hydrogen peroxide gel + sodium perborate; CP: 37% carbamide peroxide gel; CP+SP: 37% carbamide peroxide gel + sodium perborate; SP: sodium perborate + water; and control: deionized water. The specimens were sectioned and prepared for morphological analysis under SEM and analysis of calcium, phosphorus, oxygen and carbon levels using EDS. Results: A significant reduction was found in the calcium levels in enamel after treatment with CP + SP and CP (p &lt; 0.05). Carbon (organic part) was hardly altered in enamel. A significant reduction in the calcium levels was found in dentin in Groups HP+SP, CP and CP+SP. Phosphorus levels increased after SP+H20 (p &lt; 0.05) and CP (p &lt; 0.05). Carbon levels showed little variation and the largest amount was found in Groups CP and CP+SP (p &lt; 0.05); in the other groups there was no alteration. A significant reduction in the calcium levels was found in the cementum in Group CP+SP (p &lt; 0.05). Conclusion: Alterations in the enamel, dentin and cementum compositions occurred after bleaching and these alterations showed to be less significant with sodium perborate and water.Keywords: Carbamide peroxide; Hydrogen peroxide; Scanning electron microscopy; Sodium perborate; Tooth bleaching.

Effects of silver diammine fluoride on microtensile bond strength of GIC to dentine

ObjectivesThe objective of this study was to investigate the effect on the microtensile bond strength of a glass-ionomer cement (GIC), which is used for Atraumatic Restorative Treatment (ART), to normal and artificial carious dentine surface that had been treated with silver diammine fluoride (SDF) and without treatment. MethodsTwenty-four recently extracted human molars were sectioned by a low-speed blade to expose the dentine surface. These surfaces were treated by one of the four following procedures: a) immersing in artificial demineralized solution for three days; b) demineralization, followed by application of SDF drops, then washing off the precipitate and air drying; c) demineralization, followed by application of SDF drops, light-cured for 60s, then washing off and air drying; d) DI water storage for three days; e) DI water storage, followed by application of SDF drops, then washing off the precipitate and air drying; and f) DI water storage, followed by application of SDF drops, light-cured for 60s, then washing off and air drying. Then, GIC (Fuji IX, GC) was bonded onto samples and stored in the DI water for 24h and 7 days respectively. All the samples were sectioned perpendicularly into sticks with cross-sectioned area of ~1mm2. The microtensile bond strength was evaluated. SEM/EDX was performed at the interface. ResultsGenerally, the SDF or SDF light-cured pretreatments have no significant influence on the bond strength between GIC and dentine. Among the 24h carious dentine groups, the SDF light-cured had the significant highest bond strength value, compared with that of no treatment and SDF treated only. The bond strength value after 7 days DI water storage is significantly higher than that of 24h DI water storage. The artificial carious dentine had a significantly higher bond strength value, compared to that of normal dentine. ConclusionThe application of SDF on sound or deminearlized dentin prior to GIC application does not influence the mature bond strength at the adhesive interface under the conditions tested.