Mechanical Properties Of Dentin Research Articles

Evaluation of ultrasonic and mechanical methods for assessing dentin demineralization in children's permanent teeth in vitro

Relevance. With the advent of advanced methods for functional diagnostics, dentists have gained new opportunities for detecting carious lesions. However, the diagnostic sensitivity of these methods requires further investigationPurpose. To evaluate the condition of intact and demineralized dentin in children's permanent teeth using both ultrasonic and mechanical methods.Materials and methods. Divided cross-section" models were created from premolars extracted from children for orthodontic purposes. After a 20-day exposure to a demineralizing buffer solution with a pH of 4.5, both the intact and demineralized dentin cross-sections were tested using ultrasonic and mechanical methods.Results. Statistically significant differences were observed in the mean ultrasonic signal speed C between two independent sample groups: intact dentin (Group 1) and demineralized dentin (Group 2), based on Mann-Whitney U-test calculations (p = 0.01). In Group 2, the mean value of C was 27% lower compared to Group 1. Additionally, significant differences were found in the mean ultimate strength σ between two independent groups: intact dentin (Group 3) and demineralized dentin (Group 4), with Group 4 showing a 29.5% reduction in the mean σ value, according to Mann-Whitney U-test calculations (p = 0.01).Conclusion. Demineralization leads to significant changes in both the ultrasonic and mechanical properties of dentin. Statistical analysis of the laboratory test results using the "divided cross-section" model supports the effectiveness and diagnostic sensitivity of the methods applied for evaluating the extent of dentin demineralization.

Changes in the composition and mechanical properties of dentin in mouse models of diabetes

ObjectivesThis study employed mouse models of type 1 (T1D) and type 2 (T2D) diabetes to characterize the changes in tooth dentin composition and its mechanical properties. MethodsThirty-two mice were used in this study and divided into T1D, T2D and corresponding control groups. Mandibles were extracted 12 weeks after the onset of diabetes, and dentin from the first molars was evaluated in varying regions of the root. The composition was assessed using Raman Spectroscopy. Nanoindentation and Vickers indentation were employed to study the mechanical properties of the tissue. Statistical significance was evaluated by two-way analysis of variance with respect to the diabetic group and region of the tooth (p ≤ 0.05). ResultsIn the T2D model, the mineral-to-collagen ratio, hardness, and storage modulus of the intertubular dentin were significantly reduced compared to tissue from the controls, especially in the cervical regions of the tooth. The reduction in the mineral-to-collagen ratio was also observed in the T1D model, but changes in nanomechanical properties were not evident. However, the bulk hardness of the teeth in the T1D model was lower than in the littermate controls. Optical microscopy revealed significant wear of the tooth crowns in both models of diabetes, which appear to result from parafunctional activities. ConclusionThis study suggests that both type 1 and type 2 models of diabetes are associated with detrimental changes in dentin. Clinical significanceBetter understanding of how diabetes affects dentin and the contributing mechanisms will be key to improving treatments for people with diabetes.

Polyelectrolyte-Cation Complexes Using PAsp-Sr Complexes Induce Biomimetic Mineralization with Antibacterial Ability.

Remineralized dentin with an antibacterial ability is still a significant challenge in dentistry. Previously, a polyelectrolyte-calcium complexes pre-precursor (PCCP) process is proposed for rapid collagen mineralization. In the present study, the expansion concept of the PCCP process is explored by replacing the calcium with other cations, such as strontium. The results of transmission electron microscopy (TEM), 3D stochastic optical reconstruction microscopy, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, and high-resolution TEM with selected area electron diffraction demonstrate that biomimetic mineralization of collagen fibrils and demineralized dentin could be fulfilled with Sr&F-codoped hydroxyapatite (HAp) after they are treated with poly-aspartic acid-strontium (PAsp-Sr) suspension followed by a phosphate&fluoride solution. Moreover, dentin remineralized with Sr&F-codoped HAp exhibits in vitro and in vivo antibacterial ability against Streptococcus mutans. The cytotoxicity and oral mucosa irritation tests reveal excellent biocompatibility of mineralization mediums (PAsp-Sr suspension and phosphate&fluoride solution). The demineralized dentin's mechanical properties (elastic modulus and microhardness) could be restored almost to that of the intact dentin. Hence, the expansion concept of the PCCP process that replaces calcium ions with some cationic ions along with fluorine opens up new horizons for generating antibacterial remineralized dentin containing ions-doped HAp with excellent biocompatibility via biomimetic mineralization technology.

Nature-mimicking layering with composite resins through a bio-inspired analysis: 25 years of the polychromatic technique.

For decades, the dental community has discussed which materials would be the ideal substitutes for lost tooth structure. Initially, the biomimetic approach advocated that feldspathic ceramics would be the material of choice for enamel. However, given the complexity of obtaining excellent dental technicians and the financial cost, are composite resins a suitable replacement? The optical properties with opalescence and fluorescence effects, as well as this material's high fracture toughness, indicate it as a long-lasting restorative material. However, because this material depends on the operator's expertise, knowledge of layering techniques and the selection of each material for the different layers is required. Thus, knowledge of the polychromatic technique through a bioinspired approach is necessary to obtain results of life-like restorations. This article aims to review the polychromatic layering technique (PLT), considering the optical and mechanical properties of dentin and enamel and correlating these properties with current composite resins to guide clinicians in selecting the most suitable restoratives for their clinical challenges. The polychromatic layering technique is revisited, cross-referencing the properties of dentin and enamel with current composite resin restoratives and their biomimetic properties. The effectiveness and predictability of the PLT are corroborated in clinical cases of varying degrees of difficulty requiring different layering strategies. After the bio-inspired analysis, using nature as a model to be understood and followed, it is possible to note how the polychromatic technique remains current and viable in mimicking nature, providing esthetic and natural results in the layering of composite resins. Composite resins effectively replicate the optical and mechanical characteristics of natural dentin and enamel through the bioinspired approach presented by the polychromatic layering technique.

Impact of deproteinization methods on the physical and mechanical properties of dentin

This study was performed to evaluate the effects of thermal and chemical deproteinization methods on the microhardness and mineral phases of human dentin. Forty extracted non-carious human premolars were cut from below the cementoenamel junction to prepare 5 mm-thick dentin slices, and then randomly divided into four groups of 10 in each according to the treatments. Group A: thermal treatment (300 °C, rate of 30 °C /min for 10 min); Group B: 50 ml of 1N NaOH; Group C: 50 ml of 30% H2O2, at 37 °C for 7 days; Group D: control. Dry ash was obtained to measure the mass loss of organic content. The microhardness value (MHV) of the exposed root dentin was tested with a Vickers microhardness tester. The structure of the residual dentin mineral was examined using a SEM. Crystallinity was assessed by X-ray diffraction spectroscopy. Data were analyzed with one-way ANOVA and Post Hoc Tukey tests. In the comparison of microhardness values between heat, NaOH, H2O2, and control groups, significant differences were noticed between groups (P < 0.05). Since the organic component was largely removed, it can be seen that the main influence on the hardness of dentin could be the inorganic component rather than the protein content. Thermal treatment was able to completely deproteinize human dentin without significant effects on its physical and mechanical properties, while chemical deproteinization significantly changed the mechanical properties and crystallography of human dentin (P < 0.05).

Orthodontic Loads in Teeth after Regenerative Endodontics: A Finite Element Analysis of the Biomechanical Performance of the Periodontal Ligament

The objective of this study was to analyse the stress distribution in the periodontal ligament and tooth structure of a cementum-reinforced tooth, a dentine-reinforced tooth and an immature tooth during orthodontic loads using a finite element analysis. A finite element model of a maxillary incisor and its supporting tissues was developed. The root was segmented into two parts: a part that represented a root in an immature state and an apical part that represented the tissue formed after regenerative endodontics. The apical part was given the mechanical properties of dentine or cementum. The three models underwent simulation of mesial load, palatal inclination and rotation. The mean stress values and stress distribution patterns of the periodontal ligament of the dentine- and cementum-reinforced teeth were similar in all scenarios. The maturation of the root, with either dentine or cementum, was beneficial for all scenarios, since the periodontal ligament of the immature tooth showed the highest mean stress values. Under the condition of this computational study, orthodontic loads can be applied in teeth previously treated with regenerative endodontics, since the distribution of stress is similar to those of physiologically mature teeth. In vivo studies should be performed to validate these results.

Deficiency of Mineralization-Regulating Transcription Factor Trps1 Compromises Quality of Dental Tissues and Increases Susceptibility to Dental Caries.

Dental caries is the most common chronic disease in children and adults worldwide. The complex etiology of dental caries includes environmental factors as well as host genetics, which together contribute to inter-individual variation in susceptibility. The goal of this study was to provide insights into the molecular pathology underlying increased predisposition to dental caries in trichorhinophalangeal syndrome (TRPS). This rare inherited skeletal dysplasia is caused by mutations in the TRPS1 gene coding for the TRPS1 transcription factor. Considering Trps1 expression in odontoblasts, where Trps1 supports expression of multiple mineralization-related genes, we focused on determining the consequences of odontoblast-specific Trps1 deficiency on the quality of dental tissues. We generated a conditional Trps1Col1a1 knockout mouse, in which Trps1 is deleted in differentiated odontoblasts using 2.3kbCol1a1-CreERT2 driver. Mandibular first molars of 4wk old male and female mice were analyzed by micro-computed tomography (μCT) and histology. Mechanical properties of dentin and enamel were analyzed by Vickers microhardness test. The susceptibility to acid demineralization was compared between WT and Trps1Col1a1cKO molars using an ex vivo artificial caries procedure. μCT analyses demonstrated that odontoblast-specific deletion of Trps1 results in decreased dentin volume in male and female mice, while no significant differences were detected in dentin mineral density. However, histology revealed a wider predentin layer and the presence of globular dentin, which are indicative of disturbed mineralization. The secondary effect on enamel was also detected, with both dentin and enamel of Trps1Col1a1cKO mice being more susceptible to demineralization than WT tissues. The quality of dental tissues was particularly impaired in molar pits, which are sites highly susceptible to dental caries in human teeth. Interestingly, Trps1Col1a1cKO males demonstrated a stronger phenotype than females, which calls for attention to genetically-driven sex differences in predisposition to dental caries. In conclusion, the analyses of Trps1Col1a1cKO mice suggest that compromised quality of dental tissues contributes to the high prevalence of dental caries in TRPS patients. Furthermore, our results suggest that TRPS patients will benefit particularly from improved dental caries prevention strategies tailored for individuals genetically predisposed due to developmental defects in tooth mineralization.

Impact of Deproteinization Methods on the Physical and Mechanical Properties of Dentin

Impact of Deproteinization Methods on the Physical and Mechanical Properties of Dentin

Effect of glycolic acid and EDTA on dentin mechanical properties.

The aim of this study was to evaluate the effect of glycolic acid (GA) and EDTA on dentin mechanical properties. For the cohesive strength, flexural strength and fracture strength tests, the hourglass of root dentin, dentin sticks and roots standardised to 1 mm thickness were used respectively. ANOVA and Tukey tests were used for statistical analysis (P < 0.05). The results showed that EDTA and GA 17% reduced the cohesive strength values when compared to distilled water (control; P = 0.0022 and P = 0.0016 respectively), whereas the values for GA 10% group were similar to those of the control group (P = 0.093). No statistically significant difference was found among the groups for the flexural strength test (P = 0.1974). Fracture strength test showed that EDTA and GA 17% were statistically similar to each other (P = 0.7694) and statistically inferior to GA 10% (P = 0.0007 and P = 0.0004 respectively). It was concluded that 10% GA showed fewer negative effects on dentin mechanical properties.

Adjunctive procedure with solvent mixtures in non-surgical endodontic retreatment: does it affect root dentin hardness?

The aim of this study was to compare the effects of new irrigation solvent mixtures with Methyl ethyl ketone (MEK)/Tetrachloroethylene (TCE) and MEK/Orange oil (OOil), and different agitation techniques on dentin hardness. One hundred forty-four mandibular teeth were prepared and standardized, with each root's middle part transversely sectioned. Initial hardness was measured using a Vickers microhardness tester. Specimens were divided into four groups of agitation techniques (n = 36): no agitation; EndoActivator; IrriSafe; and XP-endo Finisher R. Each group was subdivided into six subgroups of irrigation protocols (n = 6): saline solution; NaOCl + EDTA; NaOCl + EDTA + MEK/TCE; MEK/TCE; NaOCl + EDTA + MEK/OOil; MEK/OOil. Final hardness was measured. The irrigation protocols NaOCl + EDTA, NaOCl + EDTA + MEK/TCE, and NaOCl + EDTA + MEK/OOil significantly decreased dentin hardness, while MEK/OOil increased it (p < 0.05). Comparing to NaOCl + EDTA sequence, dentin hardness increased significantly with the additional exposure to MEK/TCE (3%NaOCl + 17%EDTA + MEK/TCE) or MEK/OOil (3%NaOCl + 17%EDTA + MEK/OOil) (p < 0.05). There were no significant differences regarding agitation effects on dentin hardness decrease. The irrigation protocols affected dentin hardness significantly. However, the additional solvent proposals do not seem to address further concerns on dentin's mechanical properties. Agitation did not show any influence on dentin's hardness reduction.

Effect of Diabetes on Rotary Instrumentation of Dentin

IntroductionDiabetes mellitus (DM) may affect the physical and mechanical properties of dentin, which could potentially have an impact on root canal procedures. This study aimed to compare the amount of dentin removed by an endodontic rotary file, comparing dentin from diabetic patients with dentin from control patients under laboratory conditions. MethodsThe amount of dentin removed was tested using new F3 ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) files applied against the surface of prepared dentin discs for 3 different groups: diabetic type 1 (D1), diabetic type 2 (D2), and nondiabetic (normal). The dentin removed was determined by measuring the depth of penetration of the file using a digital caliper and by measuring the weight loss. Data were analyzed using Kolmogorov-Smirnov, analysis of variance, post hoc Tukey, and Pearson correlation tests (P < .05). ResultsSignificantly more dentin was removed, and the penetration of the F3 instrument was significantly higher (P < .05) in DM specimens. The statistical analysis revealed significant differences between the D1, D2, and normal groups (P < .05) for the weight loss of the specimen as well as the penetration depth at point B (P < .05). Both the weight loss and depth of penetration showed a very high positive correlation (P < .05). ConclusionsThe dentin of patients suffering from both D1 and D2 exhibited an increased amount of dentin removed compared with the nondiabetic dentin specimens. This can be observed by the increased penetration of the rotary instruments into dentin. Under certain circumstances, this may impact instrumentation, increasing procedural accidents and leading to subsequent weakening of root canal–treated teeth in diabetic patients.

Influence of volume of endodontic irrigants used in different irrigation techniques on root canal dentin microhardness.

Overzealous application of endodontic irrigants affects the root canal dentin mechanical properties. The effect of volume of endodontic irrigants on the microhardness of root canal dentin has not been studied. This study assessed the effect of volume of endodontic irrigants used in different final irrigation activation techniques on root canal dentin microhardness (RCDM). Sixty human maxillary central incisors were embedded in acrylic resin in Kuttler's endodontic cube to the level of cementoenamel junction. The root samples were randomly divided into 4 experimental groups (n = 15): Group-NI-needle irrigation, Group-PUI-continuous passive ultrasonic irrigation, Group-EndoVac-apical negative pressure system, Group combination- EndoVac + PUI irrigation. Root canals were instrumented up to size 40 (F4). The resin mounted specimens were sectioned longitudinally into two halves and were reassembled in Kuttler's kube to carry out final irrigation activation. A predetermined standardized volume of irrigants was used in each group. The RCDM was measured after root canal instrumentation and after final irrigation using Vicker microhardness tester (coronal, middle, and apical third). The reduction in RCDM values (p < 0.0086) were analyzed using Kruskal Wallis and Mann Whitney-U tests. Reduction in RCDM was observed with all the endodontic irrigating techniques tested. EndoVac and combination irrigation techniques showed maximum reduction in RCDM in all thirds of root canal. It is concluded that the volume of irrigants and agitation plays a role in reducing RCDM. The overall volume of irrigants to cause maximum reduction was 25 ml, beyond which neither volume nor agitation affects RCDM.

Effect of different irrigation protocols for applications in regenerative endodontics on mechanical properties of root dentin.

The objective of this study was to evaluate the effect of different concentrations of NaOCl with and without passive ultrasonic irrigation (PUI) on mechanical properties of human dentin for applications in regenerative endodontics (RE). Sixty single-rooted teeth were sectioned into 2 halves (n=120). Dentin bars were produced from one half for flexural strength and the other half was used for microhardness. Specimens were randomly assigned into 10 groups: G1 and G2 (control): distilled water for 30 and 60min, respectively; G3: 1.5%NaOCl for 30min; G4:1.5%NaOCl for 60min; G5: 1.5%NaOCl+PUI for 30min; G6: 1.5%NaOCl+PUI for 60min; G7: 5.25%NaOCl for 30min; G8: 5.25%NaOCl for 60min; G9: 5.25%NaOCl+PUI for 30min; G10: 5.25%NaOCl+PUI for 60min. An increase in NaOCl concentration showed highly significant reduction in mechanical properties. There was no significant difference between 1.5% NaOCl and control group except for specimens treated with PUI for 60min. NaOCl in concentrations recommended for RE did not have a significant effect on mechanical properties of dentin. However, PUI with increased irrigation time might have an effect even with low NaOCl concentration.

Human dentin characteristics of patients with osteogenesis imperfecta: insights into collagen-based biomaterials

Osteogenesis imperfecta (OI), also known as "brittle bone disease", is a rare genetic disorder of the skeleton, whose most benign form I corresponds to autosomal dominant mutations in the genes encoding type I collagen (COLA1, COLA2). Several associated skeletal manifestations are often observed but, surprisingly, while dentin defects often reflect genetic bone disorders, about half of OI patients have no obvious oral manifestations. Here, we investigated the collagen, mineral and mechanical properties of dentin from deciduous teeth collected from patients with mild form of OI and displaying no obvious clinical signs of dentinogenesis imperfecta. For the first time, an increase in the hardness of OI dentin associated with an increase in mineral content compared to healthy patients was reported. In addition, OI altered the tissue characteristics of the dentin-enamel junction but the interfacial gradient was preserved. The impact of changes in molecular structure due to mutations in OI was assessed by Raman microspectroscopy. Our results highlighted a change in the hydroxyproline-proline ratio in direct association with collagen mineralization. Our findings suggest that the evaluation of teeth could be an important aid for mild types of OI that are often difficult to diagnose clinically and provide experimental evidence that hydroxyproline content should be considered in future studies on collagen-based biomaterials.

Effect of remineralisation on the mechanical properties and tribological behaviour of human tooth dentine

With ageing and pathological factors, dentine exposure becomes more and more commonplace in the clinic. The mechanical properties of dentine are far less than those of enamel. Once exposed, dentine exhibits a weak wear-resistance and then results in many oral diseases. Therefore, it is necessary to study effective measures to improve the wear-resistance of dentine. In this study, the effect of remineralisation on the mechanical properties and tribological behaviour of human dentine was studied in vitro using nano-indentation/scratch technique. Remineralisation treatment was conducted by immersing dentine specimens in casein phosphopeptides–amorphous calcium phosphate–asparagine-serine-serine solution for 7 days after 24 h pre-treatment in polydopamine solution. Results show that after the remineralisation treatment, dentine surface is covered with a layer of dense hydroxyapatite (HA) crystals with high crystallinity and preferential orientation, and dentinal tubules are occluded. Surface hardness and elastic modulus of dentine increase by 35 and 78%, respectively, and the wear volume decreases by 86%. The crystals that occlude the dentine tubules do not fall off on the worn surface. In sum, remineralisation enhances the mechanical properties and anti-wear performance of dentine surface by forming a hard covering consisting of dense HA crystals, which is a potential measure to prevent excessive tooth wear by dentine exposure.

Effect of a new irrigant solution containing glycolic acid on smear layer removal and chemical/mechanical properties of dentin

The objective of this study was to evaluate the effects of glycolic acid (GA) (with pH 1.2 and 5) and ethylenediaminetetraacetic acid (EDTA) on the chemical and mechanical properties of dentin to investigate the potential use of GA as final irrigant in the root canal therapy. Specifically, changes in microhardness, smear layer removal, erosion, mineral content distribution, apatite/collagen ratio and flexural strength of mineralized dentin treated with GA were assessed. Saline solution was used as a negative control. Knoop microhardness (KHN) was measured on the root canal lumen of root segments. Dentin beams were used for 3-point flexural strength (σ) test. Scanning electron microscopy (SEM) images of root sections were obtained for evaluation of smear layer removal and dentin erosion on root segments and energy dispersive X-ray spectroscopy (EDS) was used for mineral content distribution. The apatite/collagen ratio (A/C) in dentin powder were examined by Fourier transform infrared (FTIR) spectroscopy. KHN, σ and A/C results were statistically analyzed with ANOVA and Tukey tests (α = 0.05). Smear layer and dentin erosion scores were analyzed with Kruskal-Wallis and Dunn tests (α = 0.05). Root dentin treated with EDTA and GA presented similar KHN regardless of the pH (p > 0.05). However, KHN was significantly reduced in EDTA and GA groups when compared to control group (p<0.001). GA showed the same ability to remove the smear layer and to cause dentin erosion as EDTA. EDS results showed that the GA and EDTA solutions did not alter the dentin mineral content distribution. The apatite/collagen ratio reduced with all irrigant solution and was the lowest with GA pH 5 (p<0.001), while σ was not significantly affected by the experimental solutions (p = 0.559). It can be concluded that GA has similar ability to remove the smear layer than EDTA. GA does not affect negatively the chemical/mechanical properties and it does not increase dentin erosion. The use of GA with low pH seems to promote less change in collagen/apatite ratio, but further studies are needed to establish an ideal clinical protocol. Therefore, this study supports the potential use of GA as an alternative final irrigation solution for root canal preparation.

Comparison of dynamic mechanical properties of dentin between deciduous and permanent teeth

ABSTRACT Purpose: Even though differences between deciduous and permanent dentin have been widely studied, their dynamic mechanical behavior has never been compared. The objective of the present study was to quantify the differences between deciduous and permanent dentin under cyclic mechanical loading, which is similar to masticatory stress. Materials and Methods: Deciduous and permanent teeth, respectively from children (9 ~ 12 years old) and young people (18 ~ 25 years old), were wet-sectioned perpendicular to the longitudinal axis and the central specimens of coronal dentin were evaluated by nanoscopic dynamic mechanical analysis (nanoDMA). Results: The average storage, loss, and complex moduli, as well as the hardness of deciduous dentin were significantly (p < 0.05) lower than those of permanent dentin. Moreover, the tan δ value of permanent dentin was significantly (p < 0.05) lower than that of deciduous dentin across the loading frequency range, indicating that viscoelastic behavior and loss of elastic energy were significantly reduced in the stiffer permanent dentin. All the nanoDMA responses showed a significant influence of the dynamic loading frequency (p < 0.05): Both deciduous and permanent dentin showed reduced viscoelasticty with increased loading frequencies. Conclusions: Compared with deciduous dentin, permanent dentin exhibits higher stiffness with reduced energy loss during deformation, and therefore superior mechanical characteristics for the mastication process.

Could calcium hypochlorite and grape seed extract keep the mechanical properties of root dentin and fracture resistance of weakened roots?

ObjectivesTo evaluate the effect of different endodontic irrigation protocols on dentin mechanical properties and fracture resistance of roots with 0.5 mm (weakened roots) and 1.5 mm of thickness. MethodIrrigation protocols were the following: Distilled water (DW) + Ethylenediamine tetraacetic acid (EDTA); grape seed extract (GSE) + EDTA; sodium hypochlorite (NaOCl) + EDTA; NaOCl + EDTA + GSE; calcium hypochlorite (Ca(ClO)2) + EDTA; Ca(ClO)2 + EDTA + GSE; chlorhexidine (CHX) + EDTA; CHX + EDTA + GSE. The samples were prepared and the values of microhardness, ultimate tensile strength (UTS), and flexural strength were obtained. Further, fracture resistance of roots with dentin thickness of 0.5 mm and 1.5 mm, and restored with fiberglass post relined with composite resin and metal crowns, were evaluated with same irrigation protocols previously described; the failure mode was evaluated as well. All tests presented normality in data distribution (Kolmogorov-Smirnov), and Analysis of Variance and Bonferroni test (α = 0.05) were performed. ResultsHigher reduction of dentin microhardness was observed in the NaOCl and NaOCl + EDTA + GSE groups (p < 0.0001). An increased in the UTS values was obtained in the CHX groups (p < 0.0001), while similar values were observed between the control and other groups (p > 0.05). The reduction of dentin flexural strength was observed in the NaOCl groups (p < 0.0001), while no significant changes were observed in the other groups (p > 0.05). With regard to fracture resistance, no statistical difference was obtained among the irrigation's protocols (p > 0.05), except for CHX (p = 0.0031) and CHX + GSE (p = 0.0001) that showed increased in fracture resistance values in roots with 1.5-mm thickness. An increased rate of irreparable failure was obtained in the NaOCl groups, whereas there was a predominance of repairable failure in the other groups. ConclusionsThe endodontic irrigation protocol has a significant impact on the dentin mechanical properties; on the other hand, do not reduce the fracture resistance of root with 0.5 mm and 1.5 mm of thickness.

The comparative evaluation of the effects of antioxidants pretreatment on remineralization of demineralized dentin - In vitro study

Context: Mechanical performance of dentin is of significant significance for the overall function of the teeth. Remineralization of carious dentin is the ultimate goal in re-establishing the functionality of the affected tissue to regain and maintain the mechanical properties of dentin. Functional remineralization of the affected dentin involves stabilization of both inorganic and organic component, but remineralizing agents stabilize only inorganic content. Hence, to stabilize organic content and to bring in functional remineralization, the use of anti-collagenolytic and anti-elastastic agents was considered for this study. Aims: The aim is to assess and compare the effect of antioxidants pretreatment on remineralization of demineralized dentin-in vitro study. Settings and Design: Experimental randomized analytical- in vitro study. Subjects and Methods: Ninety specimens were subjected to artificial caries lesions and were randomly divided into six groups based on the pretreatment with white tea, and grape seed extract (GSE) followed by casein phosphopeptide amorphous calcium phosphate and casein phosphopeptide amorphous calcium phosphate with fluoride. All the specimens were subjected to pH cycling regimen. The specimens were subjected to Vickers micro-hardness test to obtain the micro-hardness values. Statistical Analysis Used: The values were statistically analyzed using one-way analysis of variance. Results: After pH cycling, GSE showed a significant increase in micro-hardness values (46.57 ± 3.51 VHN), followed by white tea (42.56 ± 5.20) with the level of significance

Investigation of different sodium hypochlorite volumes, concentrations and times of irrigation in endodontic therapy: a systematic review

Investigation of different sodium hypochlorite volumes, concentrations and times of irrigation in endodontic therapy: a systematic review