Green synthesis of chitosan- and fluoride-functionalized silver nanoparticles using Camellia sinensis: Characterization and dental applications.

The development of new biocompatible and eco-friendly materials is essential for the future of dental practice, especially for the management of dental caries. In this study, a novel and simple method was applied for the green synthesis of silver nanoparticles (AgNPs) from the aqueous extract of Camellia sinensis (WT) and functionalized with chitosan (CHS) and NaF. The effects of WT_AgNPs application on demineralized dentin were evaluated for potential dental applications. The WT_AgNPs showed molecular groups related to organic compounds, potentially acting as reducing and capping agents. All AgNPs presented spherical shapes with crystal sizes of approximately 20 nm. Forty human molars were assigned to control: sound (SD) and demineralised dentine (DD), and experimental groups: WT_AgNPs, WT_AgNPs_NaF, and WT_AgNPs_CHS. Then, the NPs were applied to DD to evaluate the chemical, crystallographic, and microstructural characteristics of treated-dentine. In addition, a three-point bending test was employed to assess mechanical response. The application of WT_AgNPs indicated a higher mineralisation degree and crystallites sizes of hydroxyapatite than the DD group. SEM images showed that WT_AgNPs presented different degrees of aggregation and distribution patterns. The dentine flexural strength was significantly increased in all WT_AgNPs. The application of WT_AgNPs demonstrated remineralising and strengthening potential on demineralised dentine.

Comparison of the Efficacy of Two Protocol Treatments in Patients with Symptomatic Disc Displacement without Reduction: A Randomized Controlled Trial.

The aim of this study was to compare the effectiveness of arthrocentesis followed by hyaluronic acid infiltration treatment (ASH) and mandibular exercise therapy (MET) in patients with symptomatic disc displacement without reduction (DDwoR) by examining pain intensity (VAS), mandibular range of motion (MO), and quality of life (QoL). Fifty-two patients were randomly allocated into two groups, MET (N = 26) and ASH (N = 26), and therapy was applied at the baseline and one month after. Patients were followed up at 1 and 12 months after the baseline assessment. Clinical and patient-reported outcomes were compared at the baseline, 1-month follow-up, and 12-month follow-up. The study found no significant differences in VAS and MO between the ASH and MET groups at the baseline. However, while not significant, it was noted that the ASH group showed higher values for MO. Regarding OHIP-14 at 1 month of follow-up, the ASH group showed significant improvements in physical pain (p > 0.01), physical and psychological disability (p = 0.043 and p = 0.029), and handicap (p = 0.033). At the 12-month follow-up, the ASH group showed significant improvements in functional limitation, psychological discomfort, psychological disability, and handicap (p = 0.008, p = 0.001, p = 0.001, p = 0.005, respectively). ASH treatment did not reduce pain or improve mandibular range of motion more than physical therapy in patients with symptomatic DDwoR. However, ASH could be preferable given its positive long-term effects on patients' quality of life. The clinician's main objective is to prioritize the treatment plan order with a focus on the patient's quality of life. Accordingly, healthcare professionals should consider ASH as a treatment option for patients with symptomatic DDwoR who desire long-term improvement in their quality of life.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions.

OBJECTIVE: (1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces. METHODOLOGY: In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests. RESULTS: Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02). CONCLUSIONS: The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions

Abstract Objective (1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces. Methodology In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests. Results Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02). Conclusions The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Gender and Leadership Positions in Spanish Dentistry.

Dentists in Spain reached equal gender representation in 2012 and the number of female dentists has continued to grow (until 57.3% in 2020). This study aims to increase evidence about the gender distribution on the high responsibility positions and opinion leaders of the dental profession and academia. Composition of the executive comities of the main dental institutions of Spain (regional professional associations, national dental association, and scientific societies), members of the Faculty of Dentistry of the University of Granada in 2020 and speakers of the main dental congresses of 2019 (due to the lack of congress in 2020) were recorded and analyzed by genders using chi-squared test (P < .05). Mean representation of female dentists in executive committees of professional associations was 35.6%. More than 70% of presidents and vice-presidents of professional colleges and more than 60% of these positions in scientific societies were occupied by male dentists. None of dental congresses of 2019 reached equal gender participation, being 81.3% of lecturers presenting on main auditoriums male dentists. Although dental workforce in Spain is slightly overrepresented by females, leadership positions and figures among Spanish dentists doesn't seem to reflect the gender distribution of the collective. There is a lack of women occupying high-level positions in dentistry that proves the existence of the so-called "glass ceiling effect" on the profession. Further studies about sociodemographic aspects of dental workforce are needed to develop evidence-based policies for the collective.

Physicochemical and Mechanical Effects of Commercial Silver Diamine Fluoride (SDF) Agents on Demineralized Dentin.

PURPOSE: To investigate the effects of four commercial silver diamine fluoride (SDF) agents on the chemical composition and microstructural properties of dentin, and its relation to the bond strength of two adhesives. MATERIALS AND METHODS: Ninety human molars were randomly divided into sound dentin (negative control), demineralized dentin (positive control), and four experimental groups (n = 15) according to the SDF treatments (Cariestop [Biodinamica Quimica y Farmaceutica], RivaStar 1 [SDI], RivaStar 2 [SDI], and Saforide [Tokyo Seiyaku Kasei]). ATR-FTIR, x-ray diffraction, and SEM techniques were employed to characterize the compositional, crystalline, and microstructural properties of the samples. The microtensile bond strength test evaluated the bonding performance of two adhesives in demineralized dentin treated with SDF agents. RESULTS: Regarding the chemical composition, all SDF-treated groups showed a significantly higher phosphate:organic matrix ratio than the demineralized dentin group (p < 0.05). The XRD analyses revealed that the crystallite size for hydroxyapatite crystals increased on the surface areas (deep, medium, and superficial dentin) for all experimental groups compared to demineralized dentin (p < 0.05). SEM images showed that the behavior of the agents used differs on each surface treated. Bond strength values were adversely affected with both adhesive systems in the four experimental groups (p < 0.05). CONCLUSIONS: The application of SDF agents resulted in the formation of different crystalline phases of silver salts and the increase of mineralization of the pretreated demineralized dentin. However, SDF application showed a negative effect on the bond strength of the adhesives.

A gender- based approach to the current situation of Spanish dentists.

BACKGROUND: To determine the perception of Spanish dentists about the situation of the profession nowadays and how the changes occurred in dental workforce (in number and gender of the past twenty years) have affected their personal and professional lives, under a gender-based approach. MATERIAL AND METHODS: An online survey comprising of 51 opinion and socio-economic questions, divided into 9 sections of different topics, which was administered between the members of 13 professional associations. Chi-squared tests were calculated (p<0.05). RESULTS: Valid responses were received from 422 participants with a mean age of 41 years old and 66% of female dentists. Most dentists considered their selves in a "good" position, however, 72.3% of them said the profession "has had worsened". Opinions significantly differed between women and men in gender equity and the pay gap between them could be observed (29.4% of males earned more of 4000 euros a month, while only 15.1% female dentists did). Also, 49.5% of female dentists felt underrepresented in the highest association of Spanish dentists (General Council of Dentist - Consejo General de Dentistas) and 38.4% declared they have had suffered verbal violence coming from patients repeatedly. CONCLUSIONS: A generally negative perception of dentists' work quality was found among respondents. Also, opinions between males and females differed in important aspects of professional development. Further research projects are needed to have growing evidence on problems and disparities in the dental workforce which would help the institutions to make improvement actions. Key words:Dentists, Health Workforce, Survey, Gender, Spain.

Proanthocyanidin-functionalized hydroxyapatite nanoparticles as dentin biomodifier.

OBJECTIVE: This study evaluated the potential combined effects of nanohydroxyapatite and proanthocyanidin on the remineralization and collagen stabilization of demineralized dentin. METHODS: Seventy-five coronal dentin beams (6 × 1 × 1 mm3) were randomly allocated into five experimental groups (n = 15): Sound (no treatment), Control (pH-cycling), nHAp (nanohydroxyapatite), nHAp_PA (Proanthocyanidin-functionalized nanohydroxyapatite), and PA (proanthocyanidin) treatments. The sound group (negative control) were immersed in distilled water over the experimental period. The remaining groups were submitted to a pH-cycling process for 14 days. Following the de-re mineralization process, specimens corresponding to the control group (positive control) were immersed in distilled water whereas the test groups were immersed in 1 mL of respective solution treatment (nHAp, nHAp_PA, or PA) for 1 min. The dentin samples were analyzed to determine their chemical composition (ATR-FTIR and Thermogravimetric) and mineralogical (XRD) characteristics as well as their mechanical response, obtained by three-point bending test. RESULTS: Higher phosphate content (v4 PO4: ATR-FTIR) and amount of mineral (XRD) was observed in the nHAp_PA group. Furthermore, a larger induction of collagen cross-links (ATR-FTIR) and %Organic Matter (TGA) would indicate the PA incorporation and the achievement of dentin matrix stability. These effects on dentin properties were related to increasing flexural strength (MPa), demonstrating that 15% w/v nHAp_PA treatment improved the mechanical properties of the samples. SIGNIFICANCE: nHAp_PA shows significant potential for promoting remineralization while improving collagen stability into demineralized dentin in a clinically feasible period of 1 min.

Effect of Two Immediate Dentin Sealing Approaches on Bond Strength of Lava™ CAD/CAM Indirect Restoration.

The objective of this work was to compare the micro-tensile bond strength (µTBS) of CAD/CAM (Computer-Aided Design/ Computer-Aided Manufacturing) specimens cemented with different pairing of adhesives and resin-cements using two Immediate Dentin Dealing (IDS) approaches in comparison with Delay Dentin Sealing (DDS). Coronal dentin from 108 molars were divided into nine groups (n = 12) depending on the adhesive/resin-cement (A-C) assigned. Lava™ Ultimate (4 × 10 × 10 mm) was cemented according to different strategies: IDS1(cementation after dentin sealing), DDS (dentin sealing and cementation at 2-weeks), IDS2 (immediate dentin sealing and cementation at 2-weeks). Samples were sectioned and tested until failure to determine the µTBS. Failure mode was categorized as dentin/cement (DC), at Lava™ Ultimate/cement (LC) and hybrid (H). Kruskal-Wallis and Mann-Whitney U tests and influence of the type of failure on the µTBS by survival analysis with competing risk was explored. Mostly, µTBS values were equal or higher in IDS2 than DDS. In general, A-Cs that showed higher µTBS, have high percentages of LC failure. Survival analysis with competing risk between DC + H and LC values showed that some A-Cs would significantly increase the µTBS values for IDS2. A-Cs with the highest adhesion values showed a high percentage of fractures at the LC interface, suggesting that the adhesion at the adhesive/dentin interface would be higher.

Influence of de-remineralization process on chemical, microstructural, and mechanical properties of human and bovine dentin.

OBJECTIVES: This study compared the chemical composition, microstructural, and mechanical properties of human and bovine dentin subjected to a demineralization/remineralization process. MATERIALS AND METHODS: Human and bovine incisors were sectioned to obtain 120 coronal dentin beams (6 × 1 × 1 mm3) that were randomly allocated into 4 subgroups (n = 15) according to the time of treatment (sound, pH-cycling for 3, 7, and 14 days). Three-point bending mechanical test, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric (TG), and X-ray diffraction (XRD) techniques were employed to characterize the dentin samples. RESULTS: Regarding chemical composition at the molecular level, bovine sound dentin showed significantly lower values in organic and inorganic content (collagen cross-linking, CO3/amide I, and CO3/PO4; p = 0.002, p = 0.026, and p = 0.002, respectively) compared to humans. Employing XRD analyses, a higher mineral crystallinity in human dentin than in bovines at 7 and 14 days (p = 0.003 and p = 0.009, respectively) was observed. At the end of the pH-cycling, CI (ATR-FTIR) and CO3/PO4 ratios (ATR-FTIR) increased, while CO3/amide I (ATR-FTIR), PO4/amide I (ATR-FTIR), and %mineral (TG) ratios decreased. The extension by compression values increased over exposure time with significant differences between dentin types (p < 0.001, in all cases), reaching higher values in bovine dentin. However, flexural strength (MPa) did not show differences between groups. We also observed the correlation between compositional variables (i.e., PO4/amide I, CI, and %mineral) and the extension by compression. CONCLUSIONS: Human and bovine dentin are different in terms of microstructure, chemical composition, mechanical strength, and in their response to the demineralization/remineralization process by pH-cycling. CLINICAL RELEVANCE: These dissimilarities may constitute a potential limitation when replacing human teeth with bovines in in vitro studies.

Changes with age (from 0 to 37 D) in tibiae bone mineralization, chemical composition and structural organization in broiler chickens.

Broiler chickens have an extreme physiology (rapid growth rates) that challenges the correct bone mineralization, being an interesting animal model for studying the development of bone pathologies. This work studies in detail how the mineralization, chemistry, and structural organization of tibiae bone in broiler chickens change with age during the first 5 wk (37 D) from hatching until acquiring the final weight for slaughter. During the early growth phase (first 2 wk), the rapid addition of bone tissue does not allow for bone organic matrix to fully mineralize and mature, and seems to be a critical period for bone development at which bone mineralization cannot keep pace with the rapid growth of bones. The low degree of bone mineralization and large porosity of cortical bone at this period might be responsible of leg deformation and/or other skeletal abnormalities commonly observed in these birds. Later, cortical bone porosity gradually decreases and the cortical bone became fully mineralized (65%) at 37 D of age. At the same time, bone mineral acquires the composition of mature bone tissue (decreased amount of carbonate, higher crystallinity, Ca/P = 1.68). However, the mineral part was still poorly organized even at 37 D. The oriented fraction was about 0.45 which means that more than half of apatite crystals within the mineral are randomly oriented. Mineral organization (crystal orientation) had an important contribution to bone-breaking strength. Nevertheless, locally determined (at tibia mid-shaft) bone properties (i.e., cortical thickness, crystal orientation) has only a moderate correlation (R2 = 0.33) with bone breaking strength probably due to large and highly heterogeneous porosity of bone that acts as structural defects. On the other hand, the total amount of mineral (a global property) measured by total ash content was the best predictor for breaking strength (R2 = 0.49). Knowledge acquired in this study could help in designing strategies to improve bone quality and reduce the incidence of skeletal problems in broiler chickens that have important welfare and economic implications.

Effects of chronic lead exposure on bone mineral properties in femurs of growing rats.

Lead exposure has been associated with several defective skeletal growth processes and bone mineral alterations. The aim of the present study is to make a more detailed description of the toxic effects of lead intoxication on bone intrinsic material properties as mineral composition, morphology and microstructural characteristics. For this purpose, Wistar rats were exposed (n=12) to 1000ppm lead acetate in drinking water for 90days while control group (n=8) were treated with sodium acetate. Femurs were examined using inductively coupled plasma optical emission spectrometry (ICP-OES), Attenuated Total Reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and micro-Computed Tomography (µCT). Results showed that femur from the lead-exposed rats had higher carbonate content in bone mineral and (Ca2++Mg2++ Na+)/P ratio values, although no variations were observed in crystal maturity and crystallite size. From morphological analyses, lead exposure rats showed a decreased in trabecular bone surface and distribution while trabecular thickness and cortical area increased. These overall effects indicate a similar mechanism of bone maturation normally associated to age-related processes. These responses are correlated with the adverse actions induced by lead on the processes regulating bone turnover mechanism. This information may explain the osteoporosis diseases associated to lead intoxication as well as the risk of fracture observed in populations exposed to this toxicant.

Degree of conversion of a self-adhesive endodontic sealer when used as bulk material.

This study tested the null hypothesis that the opacity of RealSeal SE (RSSE) sealer makes light-curing inefficient, while the degree of conversion (DC) is similar regardless of curing method. Fourteen uniradicular teeth were sectioned at 15 mm from the apex. Root canals were instrumented using the Reciproc file system, bulk-filled with RSSE, and divided randomly into two groups (dual-cure or self-cure). DC was determined by micro-Raman spectroscopy at 24 h, 48 h, and 1 week after filling, at 6, 9, and 12 mm from the coronal end. Contrast ratio (Yb/Yw) was used to determine the opacity of the material. Descriptive statistics and nonparametric tests were used, and significance was defined as a P value of less than 0.05. Opacity was almost total by the first section, at 6 mm. In dual-cure mode, DC values at 24 h were lower in the apical section (63.8%) than in the more coronal sections and were lower than in self-cured specimens (87.4%). Light-curing of the coronal end did not improve DC. These differences remained at 48 h and 1 week. Only a small (2%) but significant increase in DC was observed in evaluations at 24 h and 1 week. (J Oral Sci 58, 333-338, 2016).

Synthesis, biocompatibility and mechanical properties of ZrO2-Al2O3 ceramics composites.

This study evaluated cell viability, microhardness and flexural strength of two ceramic composites systems (ZA and AZ), pure alumina and zirconia. There were prepared homogeneous mixtures of 78wt%Al2O3+20wt%3Y-TZP+2wt%Al2O3w (AZ) and 80wt%3YTZP+18wt%Al2O3+2wt%Al2O3w (ZA), as well as 3Y-TZP (Z), pure Al2O3 (A) and commercial monolithic 3Y-TZP (Zc). Also mouse fibroblast cells 3T3-L1 and a MTT test was carried out at 24, 48 and 72 h. The surfaces were observed with SEM and the microhardness and three-point flexural strength values were estimated. The absolute microhardness values were: A>AZ>Z>Zc>ZA. Flexural strength of Zc, Z, and ZA were around double than AZ and A. All groups showed high biocompatibility trough cell viability values at 24, 48 and 72 h. Factors like grain shape, grain size and homogeneous or heterogeneous grain distributions may play an important role in physical, mechanical and biological properties of the ceramic composites.

Effect of 30 % hydrogen peroxide on mineral chemical composition and surface morphology of bovine enamel.

A combination of atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), and gas adsorption techniques was used to characterize the effect of 30 % hydrogen peroxide (HP) on enamel surface. To perform the analyses of AAS, 1 ml of 30 % HP was added to 30 mg of a bovine enamel powder sample (150-200 µm fractions) for times of 5, 20, 60, 90, and 120 min; then 5 ml of the solution was withdrawn after each time period to measure [Ca(2+)] ions. The remaining powder was recovered and analyzed by FTIR. For SEM and gas adsorption tests, 4 × 4 mm(2) enamel sectioned samples were polished and 30 % HP was applied on the surface for the same time periods. AAS data show that 30 % HP treatment mobilized calcium from the enamel at all times studied. FTIR spectra showed that the total amount of phosphate and carbonate mineral contents such as amide I decreased significantly. SEM revealed that randomly distributed areas throughout the smooth enamel surface treatment became rougher and more irregular. These alterations indicate that surface damage increases with increasing durations of HP treatment. Gas adsorption analysis proved that bleached enamel is a typically non-porous material with a small specific surface area which decreases slightly with the 30 % HP treatment. In sum, 30 % HP induced a significant alteration of the organic and mineral part of the enamel, leading to the release of calcium and a rougher, more irregular enamel surface on randomly distributed areas.

Influence of the bracket on bonding and physical behavior of orthodontic resin cements.

The aim of the study is to determine the influence of the type of bracket, on bond strength, microhardness and conversion degree (CD) of four resin orthodontic cements. Micro-tensile bond strength (µTBS) test between the bracket base and the cement was carried out on glass-hour-shaped specimens (n=20). Vickers Hardness Number (VHN) and micro-Raman spectra were recorded in situ under the bracket base. Weibull distribution, ANOVA and non-parametric test were applied for data analysis (p<0.05). The highest values of ή as well as the ß Weibull parameter were obtained for metallic brackets with Transbond™ plastic brackets with the self-curing cement showing the worst performance. The CD was from 80% to 62.5%.

Influence of adhesive systems on microtensile bond strength of resin-based endodontic sealers to the root dentin.

OBJECTIVE: The aim of this study was to determine the microtensile bond strength to root dentin of AH Plus™ and EndoREZ® with Clearfil Liner Bond 2V and Optibond Solo™ Plus adhesive systems. STUDY DESIGN: The coronal and middle thirds of six single rooted bovine teeth was split longitudinally in a mesio-distal direction. The two halves were joined with AH Plus or EndoREZ, with and without the use of Clearfil Liner Bond 2V and Optibond Solo™ Plus adhesive systems. Build-ups were vertically sectioned into quadrangular (≈1mmx1mm) compound bars and subjected to tensile tests at a constant crosshead speed (1 mm/min) until debonding. RESULTS: Optibond® Solo Plus™ in combination with AH Plus™ and EndoREZ® showed the highest mean microtensile bond strength values, in both coronal and middle thirds. The lowest results were seen in the groups where no dentine adhesive was applied, and in those where the self-etching adhesive Clearfil Liner Bond 2V was used. CONCLUSION: The microtensile bond strength to root dentin of AH Plus™ and EndoREZ may be increased with the use of a total-etch adhesive. Key words:Adhesive systems, AH Plus, EndoREZ, microtensile bond strength, root dentin.

Ferric sulphate alterations on primary dentin and the adhesive interface.

PURPOSE: The purpose of this study was to test the hypothesis that the pulp medication ferric sulphate (FS) may remain on primary dentin, affecting its microchemical structure and the bond strength of adhesives to primary dentin. MATERIALS AND METHODS: The effects of FS and pre-bonding conditioning (37% phosphoric acid [PA] for 15 s or a self-etching primer, with or without the use of 2% chlorhexidine [CHX]) on FS-treated primary dentin were characterized using optical microscopy with Masson's and Perls' stains, variable-pressure SEM/energy-dispersive x-ray spectroscopy (VP-SEM/EDS), Fourier transform infrared spectroscopy (FT-IR), and x-ray diffraction. Ferric sulphate was applied for 30 s or 1 h for microchemical analysis. The adhesive interface and the bond strength were studied by VP-SEM/EDS and the µTBS test (1 mm2 bars, crosshead speed 0.5 mm/min), respectively. The study groups were: etch-and-rinse (E&R, Excite) adhesive (group 1); FS+E&R (group 2); FS+CHX+E&R (group 3); self-etching (SE, Adper Scotchbond) adhesive (group 4); FS+SE (group 5); FS+CHX+SE (group 6). RESULTS: Ferric sulphate application produced demineralization, gypsum formation, and adsorption of Fe on the dentin surface, and it modified the collagen structure of primary dentin. There were no effects of FS on bond strength of the tested etch-and-rinse adhesive system. FS slightly reduced the bond strength between the primary dentin and the SE adhesive, and the values were not restored by CHX (group 4 = 17.58 ± 5.52 MPa > group 5 = 14.26 ± 7.08 MPa = group 6 = 13.96 ± 4.87 MPa). CONCLUSIONS: Ferric sulphate alters the microchemical structure of primary dentin and can impair the adhesive strength of some self-etching adhesives.

Bond strength to root dentin and fluid filtration test of AH Plus/gutta-percha, EndoREZ and RealSeal systems.

OBJECTIVES: To investigate the bond strength and seal ability produced by AH Plus/gutta-percha, EndoREZ and RealSeal systems to root canal dentin. MATERIAL AND METHODS: Sixty extracted single-root human teeth, instrumented manually to size 40, were divided into three groups (n=20) according to the sealer used; G1: AH Plus, G2: EndoREZ, and G3: RealSeal sealers. After filling using the lateral condensation technique, each sealer group was randomly divided into two subgroups according to the tests applied (n=10 for µPush-out test and n=10 for fluid filtration test). A fluid filtration method was used for quantitative evaluation of apical leakage. Four 1-mm-thick slices (cervical and medium level) were obtained from each root sample and a µPush-out test was performed. Failure modes were examined under microscopy at 40x, and a one-way ANOVA was applied to analyze the permeability. Non-parametrical statistics for related (Friedman's and Wilcoxon's rank tests) or unrelated samples (Kruskal-Wallis' and Mann-Whitney's tests) allowed for comparisons of µPush-out strength values among materials at the different levels. Statistical significance was accepted for p values <.05. RESULTS: There are no significant differences among fluid filtration of the three sealers. The sealer/core material does not significantly influence the µPush-out bond strength values (F=2.49; p=0.10), although statistically significant differences were detected with regard to root level (Chi2=23.93; p<0.001). AH Plus and RealSeal obtained higher bond strength to intraradicular dentin in the medium root slices. CONCLUSIONS: There are no significant differences between the permeability and global µPush-out bond strength to root canal dentin achieved by AH Plus/gutta-percha, EndoREZ and RealSeal systems.

Bond strength to root dentin and fluid filtration test of AH Plus/gutta-percha, EndoREZ and RealSeal systems

OBJECTIVES: To investigate the bond strength and seal ability produced by AH Plus/gutta-percha, EndoREZ and RealSeal systems to root canal dentin. MATERIAL AND METHODS: Sixty extracted single-root human teeth, instrumented manually to size 40, were divided into three groups (n=20) according to the sealer used; G1: AH Plus, G2: EndoREZ, and G3: RealSeal sealers. After filling using the lateral condensation technique, each sealer group was randomly divided into two subgroups according to the tests applied (n=10 for µPush-out test and n=10 for fluid filtration test). A fluid filtration method was used for quantitative evaluation of apical leakage. Four 1-mm-thick slices (cervical and medium level) were obtained from each root sample and a µPush-out test was performed. Failure modes were examined under microscopy at 40x, and a one-way ANOVA was applied to analyze the permeability. Non-parametrical statistics for related (Friedman's and Wilcoxon's rank tests) or unrelated samples (Kruskal-Wallis' and Mann-Whitney's tests) allowed for comparisons of µPush-out strength values among materials at the different levels. Statistical significance was accepted for p values <.05. RESULTS: There are no significant differences among fluid filtration of the three sealers. The sealer/core material does not significantly influence the µPush-out bond strength values (F=2.49; p=0.10), although statistically significant differences were detected with regard to root level (Chi2=23.93; p<0.001). AH Plus and RealSeal obtained higher bond strength to intraradicular dentin in the ...