Dentin Microhardness Research Articles

The Evaluation of Dentin Microhardness After Use of 17% EDTA, 17% EGTA, 10% Citric Acid, MTAD Used as Chelating Agents Combined With 2.5% Sodium Hypochlorite After Rotary Instrumentation: An In Vitro SEM Study.

Introduction:The smear layer removed during root canal instrumentation enables penetration of irrigant solution and adhesion of root canal sealants providing a fluid tight seal of obturated root canals, necessitating its removal. The aim of the study was to compare the effect of smear layer removal by 17% Ethylene diamine tetraacetic acid (EDTA), 17% Ethylene glycol tetraacetic acid (EGTA),10% Citric acid and (MTAD solution) a Mixture of tetracycline isomer, an acid and a detergent applied as final rinse , when used along with 2.5% (NaOCl) Sodium hypochlorite and its effect on dentin microhardness.Materials and Methods:Sixty single-rooted human mandibular premolars with minimum curvature (<5°) were instrumented using rotary instrumentation till apical enlargement size 35 RaCe file 0.04 taper. During instrumentation, the canals were irrigated with 2-mL 2.5% NaOCl. After instrumentation, teeth were rinsed with distilled water and were divided into 5 groups (n = 12) according to final rinse for 1 min with 5-mL 17% EDTA followed by 5-mL 2.5% NaOCl (group 1, control group), 17% EGTA (group 2), MTAD solution (group 3), 10% citric acid (group 4), and 17% EDTA (group 5). Teeth were split through the groove prepared, and one-half of specimen were evaluated for smear layer removal using scanning electron microscopy. A score system was followed to evaluate the images and comparisons among groups were performed using Kruskal–Wallis one-way analysis. Multiple comparisons were performed using Mann–Whitney U test. The other half was evaluated for dentin microhardness using Vickers microhardness testing machine. Microhardness values were statistically analyzed using parametric one-way analysis of variance test.Conclusion:Irrigation regimen following the use of 2.5% NaOCl during instrumentation followed by application of 5-mL 17% EDTA solution for 1 min resulted in efficient smear layer removal and less decrease in dentin microhardness compared with 17% EGTA, 10% citric acid, and MTAD solution.

Effect of different irrigating solutions with surfactants on the microhardness and smear layer removal of root canal dentin: An in vitro study.

Aim:The present in vitro study was undertaken to check the effect of the different irrigating solutions with surfactants, i.e., sodium hypochlorite-(Naocl)-Extra, chlorhexidine (CHX)-Ultra, ethylenediaminetetraacetic acid (EDTA), QMix, and BioPure MTAD on the microhardness and smear layer removal of root canal dentin.Materials and Methods:A total of 120 straight rooted lower premolars were collected and were randomly divided into 2 equal groups of 60 each (n = 60). The microhardness of the samples was evaluated by Vickers hardness tester and the removal of smear layer by scanning electron microscope after irrigation of the samples with the tested solutions.Results:CHX-Ultra showed the least microhardness reduction, and EDTA showed the maximum microhardness reduction in all the tested groups. BioPure MTAD showed the maximum removal of smear layer in the apical third, and CHX-Ultra showed the minimal smear layer removal in the apical third.Conclusion:During smear layer removal, irrigating solutions cause alterations in the chemical composition of dentin, which may decrease the microhardness of the root dentin causing erosion and affecting the clinical performance of the endodontically treated teeth. Irrigating solution with maximum smear layer removal with minimum changes in microhardness should be used.

Effects of fruit vinegars on root dentin microhardness and roughness.

Aims:The aim of this in vitro study was to evaluate the effects of newly proposed irrigants; the pomegranate, apple cider, and grape vinegars in comparison with contemporary irrigants; sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX), and octenidine-hydrochloride (OCT) on microhardness and surface roughness of human root canal dentin.Subjects and Methods:The crowns of the 105 mandibular incisor teeth were removed, and roots were separated longitudinally. Root halves were embedded in acrylic-resin and were ground flat. The specimens were randomly divided into following six test groups (n = 30); pomegranate vinegar, apple cider vinegar, grape vinegar, 2.5% NaOCl, 2% CHX, OCT and a control group based on the treatment time, samples were then divided into two subgroups (15 min or 30 min). Each specimen was first subjected to surface roughness and then Vickers microhardness testing. The data were statistically analyzed.Results:Pomegranate, apple cider, and grape vinegars exhibited similar roughness values (P > 0.05) and presented higher results than other groups (P < 0.05). There was no statistically significant difference between the microhardness values of the irrigant groups (P > 0.05). The microhardness decreased when the exposure time increased from 15 min to 30 min (P < 0.05).Conclusions:The use of vinegar for endodontic irrigation may have a softening effect on root canal dentin with time and may increase dentin roughness.

Effect of Final Irrigation Protocol on Dentin Microhardness

Endodontic therapy is essentially a debridement procedure that requires the removal of the irritants of the canal and periapical tissue if success is to be gained. The debridement may include instrumentation of the canal, placement of medicament and irrigants. Complete cleaning of the root-canal system requires the use of irrigants that dissolve organic and inorganic material. The study aimed to evaluate changes in dentin microhardness after canal irrigation with different solutions. Twenty four freshly extracted human mandibular molars (distal roots with single canals) were used. 10mm root length was taken as standard length. The roots were embedded into auto polymerizing acrylic resin using plastic molds before the canals preparation and micro hardness test. The distal roots were prepared with one shape rotary file. Before the preparation each root was irrigated with 1ml distilled water. Then the roots were divided into four groups according to the final irrigation protocol: Group A: NaOCl 2.5%, Group B: EDTA 17%, Group C: Citric Acid 40%, Group D: Distilled Water. For (Vicker microhardness test) the same load and time 500 g test load for 20 seconds, will be conducted three times at distance 0.5mm from canal lumen ; thus there will be 9 indentations on each specimen surface. An average of the three readings for each test condition will be recorded as the VHN value of a specimen. Comparing all four groups statistically there was no significant difference among them. The mean values were found more reduced in EDTA group followed by NaOCL group, and then Control and Citric Acid groups. All the groups showed reduction in dentin microhardness. EDTA group showed the maximum reduction followed by NaOCL group, and least with Citric Acid group.

Effect of chemical and natural irrigant solutions on microhardness of root dentin – an in vitro study

Introduction: Modifications in the mechanical properties of dentin may reduce the fracture resistance of tooth, especially after endodontic treatment. The aim of present study was to evaluate the effect of the irrigation with different root canal irrigants on the microhardness of root dentin. Methods: The coronal portion of 60 single-rooted bovine incisors was sectioned and the pulpal tissue removed using endodontic K-files. The roots were cut transversely to obtain 2 fragments, which were embedded in acrylic resin and randomly distributed into six groups (n=20) according to the irrigation protocol: distilled water (DW) (control); 2% chlorhexidine solution (CHX); 6% sodium hypochlorite (NaOCl); 6% calcium hypochlorite (Ca[OCl]2); QMix; and 6.5% grape seed extract solution (GSE). The solutions were kept in contact with the root dentin specimens for 30 min. After that, irrigation with 5 mL of DW was performed. The Vickers microhardness was determined by performing three indentations in all specimens, using 300-g load and 20-second dwell time. The first indentation was made 1.000 µm from the root canal entrance, and two other indentations were made at a distance of 200 µm from each other. The microhardness value for each specimen was obtained as the average of the results for the three indentations. Data were statistically analyzed using one-way ANOVA with 5% significance level. Results: All the tested irrigant solutions maintained the same microhardness level of the root dentin when compared to the control group, with no statistically significant differences between them (p&lt;0.05) Conclusion: The tested irrigant solutions did not present ability to modify the microhardness of root dentin.

The Effect of Poly Amido Amine Dendrimer, Gluteraldehyde and Their Combination on the Micro Hardness and Micromorphology of Demineralized Dentin

Objective: The aim of this study was to evaluate the remineralizing effect of Poly (amido amine) dendrimer, Gluteraldehyde and their combination on demineralized dentin at different time intervals. M ate rials and Methods: A total of one hundred and twenty dentin discs were prepared from extracted teeth (n=120), each dentin sample was immersed in 10% citric acid solution for 30 seconds. The samples were divided into two main groups (60 each) according to the assessment time, one week assessment, and four weeks assessment, These two groups were further subdivided into three groups according to the treatment materials; group (1), (n==10): pure G3.0 PAMAM dendrimer, group (II), (n=10): Gluteraldehyde was applied to the demineralized dentin, Group (III), (n=10): a combination of PAMAM dendrimer and Gluteraldehyde. Each group has its control group (n=10) which didn”t receive any treatment. Each treated group with its corresponding control one was placed in a separate container of artificial saliva for one and four weeks. The samples were subjected to microhardness test and Scanning Electron Microscope (SEM). Resu Its: after one week assessment, the results revealed that the highest mean value recorded for PAMAM group (10.9%) followed by PAMAMGluteraldehyde group (8.3%) while Gluteraldehyde group recorded the lowest mean value (5.26%). This difference was statistically insignificant. After four weeks assessment, the results revealed that the highest mean value recorded for PAMAM-Gluteraldehyde group (14.77%) followed by PAMAM group (14.34%) while Gluteraldehyde group recorded the lowest mean value (8%). This difference was statistically insignificant Conclusions: All treatment materials used were effective in increasing dentin microhardness and produced micromorphological changes of the dentin surface in terms of occluding the orificies of dentinal tubules to variable degree

Evaluation and Comparison of smear layer removal and dentin microhardness using Maleic acid, EDTA and MTAD as irrigant.

Introduction: The aim of this study was to evaluate and compare the efficacy of various irrigating solutions on smear layer removal and dentin microhardness. Material & Method: 50 single rooted teeth were equally divided in two halves to evaluate smear layer removal and measure dentin microhardness. The teeth were randomly divided into 5 groups (n=10) based on the final irrigant used (Group 1: 17% EDTA, Group 2: 7% Maleic Acid,Group 3 10% Maleic Acid, Group 4: MTAD, Group 5: Saline (Control). Chemomechanical preparation was performed with a step back technique using K files. The half roots from each group were prepared for SEM to evaluate the smear layer in coronal, middle and apical thirds and the other halves were prepared to measure the dentin microhardness. Statistical Analysis: Statistical comparison was done by Kruskal Wallis One way ANOVA along with Post HOC Tukey HSD test with a significance level of 0.05. Result: The smear layer removal efficacy was comparable for all irrigants at coronal and middle one third regions. Apical one third region showed MTAD and 10% Maleic Acid to be most effective followed by 7% Maleic acid then 17% EDTA. The dentin microhardness was most affected by MTAD and 10% Maleic acid followed by 17% EDTA and least affected by 7% Maleic acid. Conclusion: 7% Maleic acid proved to be quite effective in smear layer with least affect on dentin microhardness.

Enamel and dentin microhardness of deciduous and permanent teeth formed in fluoride-iodine deficiency

Aim. To study the microhardness of enamel and dentin of deciduous and permanent teeth formed in fluoride-iodine deficiency.&#x0D; Methods. Enamel and dentin microhardness was examined on sections of 47 deciduous and 43 permanent teeth. Six topographic zones were examined on each tooth section, 24 imprints were performed. Enamel and dentin microhardness was determined on PMT-3M device and by Vicker’s Hardness Test with a load of 50 g for 5 seconds.&#x0D; Results. Enamel and dentin microhardness of permanent teeth is higher than that of deciduous ones. In the surface layer of enamel the microhardness of permanent teeth is 2.33-2.09 times higher compared to deciduous teeth (in incisors - by 2.24 times, canines - by 2.09 times, molars - by 2.33 times); 2.25-1.94 times higher in the middle layer (in incisors - by 2.17 times, canines - by 1.94 times, molars - by 2.25 times); 2.15-1.89 times higher in the enamel layer at the enamel-dentine junction (in incisors - by 2.15 times, canines - by 1.89 times, molars - by 2.03 times). In the dentin layer at the enamel-dentin junction, dentin microhardness of permanent teeth is 1.90-1.71 times higher than of deciduous ones (in incisors - by 1.78 times, canines - by 1.71 times, molars - by 1.90 times); 2.14-2.0 times higher in the middle dentin layer (in incisors - by 2.08 times, canines - by 2.0 times, in molars - by 2.14 times); 2.05-1.71 times higher in the near-pulp layer (in incisors - by 2.05 times, canines - by 1.71 times, molars - by 1.87 times).&#x0D; Conclusion. Enamel and dentin microhardness of deciduous and permanent teeth formed in fluoride-iodine deficiency varies considerably; microhardness of hard tissues of permanent teeth is approximately 2 times higher than that of deciduous teeth.

Dentin pretreatment with Er:YAG laser and sodium ascorbate to improve the bond strength of glass fiber post.

Root-filled teeth that received fiber posts most frequently fail at the adhesive interface between resin cement and dentin. The objective of this study is to evaluate the effect of Er:YAG laser and/or sodium ascorbate (SA) on bond strength, microhardness of dentin, and penetration depth of cement into dentinal tubules. Forty-eight bovine incisor roots were endodontically treated, post spaces were prepared and equally divided into four groups (n= 12): G1-distilled water (control); G2-10% SA (10min); G3-Er:YAG laser (150mJ/4Hz/40s), and G4-Er:YAG laser + 10% SA. Glass fiber posts were cemented and roots sectioned into slices. In the first slice, the push-out bond strength (MPa) and failures were analyzed by confocal laser scanning microscope (CLSM). The second slice was subjected to microhardness test (KHN) and CLSM to assess the cement penetration. ANOVA and Tukey test were used for bond strength and microhardness data and Kruskal-Wallis and Dunn tests for the cement penetration (α = .05). The SA-treated samples had higher bond strength (10.02 ± 5.45a), similar to Er:YAG laser (9.91 ± 4.62a) and Er:YAG laser + SA (8.09 ± 4.07a). The least values (P < .05) were found on control (4.02 ± 2.39b). Significant differences were observed on root thirds (P < .05): cervical > middle > apical. There was a predominance of adhesive failures. The microhardness test revealed no differences between groups (P > .05). The experimental groups (G2, G3, and G4) had highest penetration into dentinal tubules when compared to the control (G1). Dentin pretreatments with Er:YAG laser or SA improved bond strength of cement-post-dentin interfaces; however, no synergistic effect of both treatments combined was observed.

Evaluation of the effects of the solution used for electrochemical dissolution of nickel-titanium endodontic files on dentine structure, microhardness and cell viability.

To evaluate the effects of the [NaF 12gL-1 +NaCl 1gL-1 ] solution used in the electrochemical dissolution process of fractured endodontic files, as well as its NiTi-containing product, on dentine hardness, topography and human fibroblast viability. Sixty single-rooted human teeth were evaluated for dentine microhardness using the Vickers hardness test and the area and number of dentinal tubules by scanning electron microscopy. The samples were divided according to the dentine surface treatment: distilled water; 17% EDTA; [NaF 12gL-1 +NaCl 1gL-1 ]; and 17% EDTA+[NaF 12gL-1 +NaCl 1gL-1 ]. Thirty-six single-rooted human teeth were divided according to the irrigation protocol: Dulbecco's Modified Eagle's Medium+10% foetal bovine serum; 5.25% NaOCl; [NaF 12gL-1 +NaCl 1gL-1 ]; and [NaF 12gL-1 +NaCl 1gL-1 +NiTi]. The extracts in contact with the apical foramen were used in the MTT assay to evaluate human fibroblast viability, with dilutions of 100%, 50%, 25% and 12.5%. Statistical tests used were paired t-tests, one-way anova, Tukey's test, Kruskal-Wallis test and Dunn's post-test. The [NaF 12gL-1 +NaCl 1gL-1 ] solution did not modify dentine microhardness or the average dentinal tubule area. However, EDTA induced changes in dentine structure and microhardness (P<0.05). The [NaF 12gL-1 +NaCl 1gL-1 ] solution, and its NiTi-containing product had lower cytotoxicity than NaOCl at dilutions of 25% and 50% (P<0.01). The [NaF 12gL-1 +NaCl 1gL-1 ] solution did not alter dentine microhardness or damage the dentine structure. It also demonstrated lower cytotoxicity than NaOCl.

The concentration of calcium phosphate spheres on micro hardness of dentin

Calcium phosphate spheres was synthesized by hydrothermal method and used to make anti-sensitivity Toothpaste. The toothpaste was used to apply on dentin surface daily. The calcium phosphate facilitated more remineralization effect as the applied time was 7 days compared to fewer days. The new remineralized layer leads to approximately 22% decrease of micro hardness of dentin.

Correlation of ultrasound microscopy and Vickers hardness measurements of human dentin and enamel — A pilot study

ObjectiveTo investigate if Vickers microhardness of dentin and enamel correlated with acoustic velocity c(l) or acoustic reflection from the sample’s top (amplitude). MethodsEight transversal sections of a sound human tooth were investigated with scanning acoustic microscopy (SAM) and Vickers microhardness measurements. Longitudinal acoustic velocity c(l), amplitude and microhardness MHV were evaluated and for each c(l) test point corresponding amplitude and MHV were linearly interpolated and graphically analyzed. Spearman rank order correlation (rS) was calculated (p<0.05). Resultsc(l) was predominantly 6100–7000ms−1 in enamel and 3800–4600ms−1 in dentin and correlated significantly with MHV with 27–420 in enamel and 20–90 in dentin (rs=0,57). Amplitudes significantly correlated with MHV, too, but even better (rs=0,77). SignificanceAcoustic velocity and amplitudes were appropriate to detect microhardness differences of dentin and enamel and certain value ranges of both could be assigned to certain MHV ranges. Further research is needed to differentiate more precisely between the different hard tooth tissues.

GRAPE SEED EXTRACT AND DENTIN REMINERALIZATION

Objective: The motivation of this study was to investigate the effect of grape seed extract on dentin remineralization. Methodology: Sound dentin disks were prepared from the buccal surfaces of human impacted third molars. The specimens were stored in demineralizing solution for 72 hours at room temperature to create artificial carious lesions. They were divided into four groups according to the treatment used; 15% GSE, 1000 ppm sodium fluoride, artificial saliva meanwhile teeth in the fourth group were kept without treatment as a negative control group. An in vitro pH cycling model for eight successive days was done. Subsequently micro-hardness of the specimens and their micro-morphological appearance were evaluated using micro-indenter and Environmental scanning electron microscope (ESEM) respectively. Data were statically analyzed. Results: The results indicated that there was a significant increase in dentin micro-hardness values of GSE and NaF groups in comparison to the demineralized and artificial saliva groups. The ESEM micrographs confirmed the micro-hardness results. Conclusions: GSE is a promising natural remineralizing agent for treatment of the demineralized dentin.

Вплив хемо-механічної обробки кореневого каналу на мікротвердість дентину

Summary. Dentin and enamel microhardness is one of the main characteristics when studying mechanical qualities of the tooth and chewing function, and serves as an indicator of hard tissue functional stability and strength. Irrigating and shaping of root canal during the endodontic treatment, cause changes of dentin properties and are the main reasons of tooth cracks and vertical root fractures.The aim of the study – to check the dentin mechanical properties, namely microhardness, after using the improved irrigation protocol during the root canal chemo-mechanical treatment.Materials and Methods. This comparative study researches the changes of root-dentin microhardness before and after the root canal chemo-mechanical treatment using the improved irrigation protocol. Study was performed with a Vickers Hardness Tester. Totally 48 specimens were divided into 4 groups (n=12): 1) vital teeth; 2) necrotic teeth; 3) previously treated teeth obturated with gutta-percha; 4) previously treated teeth obturated with resorcinol-formaldehyde. In each group 6 specimens were tested before and 6 after the root canal treatment. The data were subjected to statistical analysis using statistical hypothesis testing method based on the comparison of the distribution by Student.Results and Discussion. The average data of root dentin microhardness before and after root canal chemo-mechanical treatment using the improved irrigation protocol were determined. Under the conditions of the current study, in all groups, no negative effect when continuously using alternation of irrigants during the chemo-mechanical treatment was found, although root dentin microhardness was reduced. Data outcome showed root dentin microhardness changes in permissible limits and doesn’t contradict with previous studies.Conclusions. Alternating the use of 6 % NaOCl and 17 % EDTA with Sodium Thiosulfate in between during chemo-mechanical treatment reduces root dentin microhardness in permissible limits and doesn’t have harmless effect on tooth.

An in- vitro evaluation the effect of endodontic irrigation solutions on the microhardness of root canal dentin.

The aim of this study was to evaluate the effect of 5.25 sodium hypochlorite and17%EDTA on the microhardness of root canal dentin .Fifteen, maxillary incisor teeth extracted for periodontal reasons were used. Thecrowns of the teeth were removed at the CEJ. The roots were separated longitudinallyinto two segments, embedded in acrylic resin, and polished. A total of 30specimenswere divided into 3 groups of 10 teeth at random according to the irrigation solutionused: group 1: 5.25% NaOCl for 1min; group 2: 17% EDTA for 1 min; and group 3:distilled water (control). Each group was submitted to Vickers microhardnessindentation tests. The data were recorded as Vickers numbers and the results wereanalyzed statistically by using one-way ANOVA.The results showed that, irrigation with either sodium hypochlorite or EDTAdecreased the microhardness value of root dentin. Irrigation with EDTA gave morereduction of dentin compared to sodium hypochlorite. The reduction of VHN ofdentin following the irrigation treatment was statistically significant (p&lt; 0.05 ) .Both sodium hypochlorite and EDTA irrigation solution significantly reduced themicrohardness of root dentin..

Effect of Root Repair Materials and Bioactive Glasses on Microhardness of Dentin.

Introduction:The use of bioactive glasses to re-establish or increase mechanical properties of the root dentin may be an interesting alternative. The aim of this study was to evaluate the effect of root repair materials and bioactive glasses on the microhardness of human root dentin. Methods and Materials:Sixty-four sectioned palatal roots of human molars were prepared and two slices were obtained of the middle third of each root (one corresponding to the control group, without treatment, and the other to the experimental group). The pairs of slices were randomly divided into four groups (n=16). The root canal of experimental slices were filled with one of the following materials: mineral trioxide aggregate (Angelus MTA, Angelus, Londrina, Paraná, Brazil), EndoSequence Root Repair Material (ERRM, Brassler, Savannah, GA, USA), Bioglass (45S5) and an experimental niobophosphate glass (NbG). The specimens were stored in an oven at 37ºC, in an environment with 100% humidity for 60 days. The specimens were subjected to a microhardness test. Four indentations were made at a distance of 20 µm from the root canal lumen. For microhardness analysis, comparing the experimental groups and their respective controls, the Student’s-t test was applied. For comparison of the percentage increase in microhardness between the groups, the data were statistically analyzed by using One-way ANOVA and Tukey’s test. The level of significance was set at 0.05. Results:All the materials significantly increased the dentin microhardness values (P<0.05). MTA showed a higher increase in microhardness (94.8±42.7%), similar to that of EndoSequence (62.3±39.9%). The 45S5 (46.5±30.0%) and NbG (53.8±31.3%) showed the lowest percentages of increase in microhardness, but were statistically similar to those of EndoSequence. Conclusion:All the materials tested were capable of increasing root dentin microhardness.

A Novel Enamel and Dentin Etching Protocol Using α-hydroxy Glycolic Acid: Surface Property, Etching Pattern, and Bond Strength Studies.

To determine the use of α-hydroxy glycolic acid (GA) as a surface pretreatment for dental restorative applications. The etching pattern of GA pretreatment of dental hard tissues was assessed by surface microhardness and scanning electron microscopy (SEM). The effectiveness of GA surface etching on the enamel and dentin resin bond strengths was assessed using two etchant application modes (rubbing and no rubbing) and three adhesive systems (Single Bond [SB], One Step Plus [OSP], and Scotchbond Universal [SBU]). Knoop microhardness measurements were carried out on polished enamel and dentin surfaces before and after treatment with 35% GA, 35% phosphoric acid (PA), or distilled water (control group) for 30 seconds. The microtensile bond strength test was carried out on enamel and dentin. Ultrastructural analysis of the surface and interfacial interaction was qualitatively accomplished using SEM. Etching with either PA or GA significantly decreased the enamel microhardness, with GA being significantly less aggressive than PA ( p<0.001), while both acids showed similar decreases in dentin microhardness ( p=0.810). SEM revealed similar etching patterns of GA and PA, while apparently a thinner hybrid layer was observed for GA groups. In dentin, the bond strengths were statistically similar between PA and GA groups, regardless of the etchant application mode ( p>0.05). However, rubbing of GA enhanced the bond strength to enamel. PA and GA significantly increased the SBU bond strength to enamel when compared to SB and OSP ( p<0.05). GA effectively etched enamel and dentin surfaces, resulting in bond strength values similar to those associated with traditional PA. GA is a suitable enamel and dentin surface etchant for adhesive restorative procedures.

Microhardness of hard tooth tissues before and after composite restorations in vitro

The article deals with the results of the study of enamel, dentin and composite restorations of permanent teeth in vitro, regarding microhardness and micromorphology of the enamel surface, dentin and composite restorations of the samples got by Knoop method. Domestic photopolymer material Restavrin was used as a composite. It was compared with Restavrin under the sealant Optiguard. Microhardness of the restoration was measured on the 10, 30 and 45 day after putting into glass-tubes with artificial saliva filled with mixture of oral streptococcus S. mutans and S. oralis. At all dates of research with the covering by Optiguard, microhardness of enamel and dentin in the places of contact with Restavrin and composite, turned out to be actually higher (p

Microhardness and shear bond-strength of carious dentin after fluorescence-aided or conventionally excavation: (An in-vitro comparison).

BackgroundTo compare the fluorescence-aided and conventionally excavated dentin with microhardness and shear bond strength(SBS) tests.Material and MethodsTwenty-four teeth with dentin caries were bisected through the center of the lesion into two halves. Forty-eight dentin specimens were embedded and mounted in an acrylic resin. All carious tissue was removed and classified as caries free using conventional visual tactile criteria. Then half of the specimens(n=24) were reinspected with fluorescence-aided caries excavation light(FACE) (FaceLight, W&H Dentalwerk, Bürmoos GmbH, Austria). Specimens were subjected to microhardness and shear bond strength testings. The fracture mode analysis was also performed. The data were compared with Student’s t test and Chi-square test.ResultsResidual caries was observed in 2 out of 24 conventionally excavated specimens with FACE inspection(p>0.05). Mean Vickers hardness of the dentin was 61.5±5 in the FACE group and 70.3±3 kg/mm2 in the conventionally excavated group(p>0.05). The mean SBS value of FACE group was 11.42±1.63 MPa and 18.27±1.43 MPa in conventionally excavated group. There was no statistically significant difference between conventional and FACE groups for microhardness and SBS tests(p>0.05). There were also no significant differences on the fracture mode distributions of the groups(p>0.05).ConclusionsFACE method could be considered as a promising technique for removing infected dentin. Key words:FACE, conventional excavation, residual caries detection, shear bond strength, microhardness.

The Effect of Zingiber officinale Roscoe (Ginger) on Dentin Microhardness: An in vitro Study

It has been established that conventional root canal irrigants cause detrimental effect on the physico-chemical properties of root dentin. This study aims to determine the effect of a novel root irrigant, ginger or Zingiber officinale Roscoe essential oil on root dentin microhardness. Eighty root halves of extracted human teeth were used and prepared by embedding them individually in autopolymerizing acrylic resin. These samples were then divided into four groups (n = 20 each), i.e., i) 0.5% Z. officinale Roscoe oil, ii) 2.5% sodium hypochlorite (NaOCl, positive control), iii) 17% ethylenediaminetetraacetic acid (EDTA, positive control) and iv) normal saline (negative control). Dentin microhardness was measured using Vickers Microhardness Tester with a 50 g load and a 10-second dwell time, before and after immersion in respective solutions for 5 minutes. Measurements were taken in Vickers hardness number (VHN). All samples showed reduction in the microhardness reading; with Z. officinale Roscoe: 34.24 to 25.89, NaOCl: 31.47 to 26.34, EDTA: 33.08 to 26.04 and saline: 29.82 to 27.61 VHN. Although there was significant reduction within the Z. officinale Roscoe group (p &lt; 0.001), the change was indifferent when compared among groups (post hoc Tukey’s HSD test p &gt; 0.05). Within the limitations of this study, Zingiber officinale Roscoe essential oil does alter dentin microhardness but to a similar extent as NaOCl and EDTA.