NaOCl Pretreatment Research Articles

Improving Recovery of Diatoms Bio-Silica Using Chemical Treatment with VAUS TM.

High-temperature baking is a typical method to remove organic matter from diatoms, but it's not suitable for bio-silica because of the high crystallinity. This study provides a method using the VAUS™ to remove organic matter from diatoms more quickly and biocompatibly. Organic matter was removed by using VAUS™, while NaOCl was utilized to remove the organic matter from the silicate frustule. The optimal frequency for organic matter removal was investigated to domestically produced M. nummuloides. The removal efficiency of TOC/TN was calculated and analyzed. The C and Si elements were analyzed in EDS, while visual confirmation of organic matter removal was analyzed by using XRD. TOC RE% at a frequency of 35kHz exhibited the highest value, indicating a statistically significant difference. XRD analysis demonstrated that the organic matter was almost removed using NaOCl compared to the high-temperature baked M. nummuloides. In the EDS analysis, there were significant differences in the C and Si elements with respect to frequency. This is very similar to the values from the positive control group, high-temperature baked M. nummuloides. This new procedure of applying periodic negative pressure to NaOCl pre-treatment is considered to be an effective method of chemically removing organic matter from diatoms.

CLSM-Guided Imaging for Quantifying Endodontic Disinfection.

Elimination of microbes in the root canal system is crucial for achieving long-term success in endodontic treatment. Further efforts in study design and standardization are needed in order to improve the validity and comparability of in vitro results on endodontic disinfection procedures, in turn improving clinical outcomes. This study optimizes two models at all steps: tooth selection, pretreatment, inoculation method (by growth or centrifugation), and confocal laser scanning microscopy (CLSM)-guided imaging of LIVE/DEAD-stained specimens. Individual anatomical conditions lead to substantial differences in penetration depth. Sclerosis grading (SCG), a classification system introduced in this study, provides information about the sclerosis status of the dentine and is helpful for careful, specific, and comparable tooth selection in in vitro studies. Sonically activated EDTA for the pretreatment of roots, inoculation of Enterococcus faecalis in an overflow model, 3-4 weeks of incubation, as well as polishing of dentine slices before staining, led to advances in the visualization of bacterial penetration and irrigation depths. In contrast, NaOCl pretreatment negatively affected performance reproducibility and should be avoided in any pretreatment. Nonsclerotized teeth (SCG0) can be used for microbial semilunar-shaped inoculation by centrifugation as a "quick-and-dirty" model for initial orientation. In conclusion, CLSM-guided imaging for quantifying endodontic infection/disinfection is a very powerful method after the fine-tuning of materials and methods.

Effectiveness of sodium hypochlorite treatment on the bonding of four adhesive systems to fluorotic enamel.

The study evaluated the effect of sodium hypochlorite (NaOCl) treatment on fluorotic enamel bonding of four adhesive systems. They were Single Bond 2 (SB2), Prime&Bond NT (PBN), Clearfil SE Bond (CSB), and Single Bond Universal (SBU). One hundred eighteen extracted moderate fluorotic molars were divided into eight groups according to NaOCl pretreatment and four adhesive systems. The microshear bond strength (μSBS), etching pattern, and penetration depth (PD) were observed. The statistical method was two-way ANOVA and least significant difference (LSD) test (α=0.05). The application of NaOCl significantly increased the μSBS of PBN and SBU (p<0.05). The enamel-etching pattern of CSB and SBU was deeper under SEM. A noticeable increase of PD was in SB2 and SBU after the application of NaOCl (p<0.05). Pretreatment of 5.25% NaOCl for the 60 s can increase μSBS of PBN and SBU, PD of SB2 and SBU, and improve enamel-etching pattern of CSB and SBU to fluorotic enamel.

Effects of Surface Preparation with Sodium Hypochlorite on Shear Bond Strength and Residual Adhesive of Orthodontic Brackets on Primary and Permanent Teeth

Objective: To investigate the effects of surface preparation with sodium hypochlorite (NaOCl) on bracket shear bond strength and amount of residual adhesive on primary and permanent teeth. Materials and Methods: 24 permanent premolars, 12 in each group (groups I and III), and 24 primary molars, 12 in each group (groups II and IV) were included. In group I and II, 37% phosphoric acid was applied to the tooth surfaces, without using any other agent. In Group III and IV, 5.25% NaOCl was first applied. Following washing and drying, surface roughening was performed with phosphoric acid. The shear bond strengths (SBS) of the brackets bonded to the tooth surfaces was measured. After debonding, the base of each bracket was examined for adhesive remnant index (ARI) scores. Results: There were no statistically significant differences in SBS values between primary and permanent teeth with and without preparation with NaOCl(P&amp;gt;0.05). Mean SBS(18.55±14.98 MPa) was higher in permanent premolars subjected to surface deproteinization with NaOCl (group III) when compared with other groups, but the difference was not significant. There was no significant difference in ARI scores between the groups. Conclusions: The bond strength of orthodontic brackets or the distribution of ARI scores were similar between groups with and without NaOCl pretreatment. Hence, it can be concluded that conventional bonding procedures applied without any additional preparation to primary teeth are sufficient and the debonding of brackets didn’t cause any harm to enamel surfaces.

Deproteinization of caries-affected dentin with chemo-mechanical caries removal agents and its effect on dentin bonding with self-etch adhesives

ObjectivesTo evaluate the micro-tensile bond strength (μTBS) of self-etch adhesives (SEA) to normal and caries-affected dentin after smear layer deproteinization with papain enzyme-based and NaOCl-based chemo-mechanical caries removal agents (CRAs) and to compare their efficacy to a 6 % NaOCl solution. MethodsForty extracted human molars with occlusal carious lesions were randomly divided into four pretreatment groups: no treatment (control), Papacarie for 60 s, Carisolv for 60 s, and 6 % NaOCl for 15 s. After pretreatment, Universal Bond Quick ER (UBQ, one-step, 1-SEA) or Clearfil SE Bond 2 (CSE, two-step, 2-SEA) was applied to the pre-treated surface, and built-up with resin composite (Clearfil AP-X). The μTBS test was performed after 24 h water storage of the specimens at 37 °C, and the modes of failure were determined under SEM. Deproteinizing effects of the tested agents on smear layer-covered dentin was quantified by changes in the amide:phosphate ratio using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) analysis. ResultsOn caries-affected dentin the μTBS improved significantly after pretreatment with Papacarie, Carisolv, and 6 % NaOCl with both SEAs (p < 0.05). Papacarie pretreatment significantly improved the μTBS of UBQ on normal dentin compared to NaOCl pretreatment (p < 0.05). ATR-FTIR revealed that all agents significantly decreased the amide:phosphate ratio on the smear layer-covered normal and caries-affected dentin (p < 0.05). ConclusionsSmear layer deproteinizing with papain enzyme-based and NaOCl-based gel CRAs was effective in improving the micro-tensile bond strength of self-etch adhesives to caries-affected dentin. Clinical significanceSmear layer deproteinization with Papacarie (a papain enzyme-based gel) or Carisolv (a NaOCl-based gel) can improve the μTBS to normal and caries-affected dentin bonded with 2-step self-etch adhesives.

Bonding to caries affected dentine

ObjectivesDentine replacement materials are often placed over caries affected dentine (CAD). The aim of this study was to compare the bonding characteristics and interactions of selected hydraulic calcium silicate-based dentine replacement materials to CAD and sound dentine. MethodsThree hydraulic calcium silicate-based dentine replacement materials were assessed: Retro MTA, Biodentine and Theracal LC. Material characterization was done by scanning electron microscopy and X-ray diffraction analyses. Blocks of sound and CAD were prepared and standardized by Vickers microhardness testing. Half of the affected and sound dentine blocks were pretreated with 5.25% NaOCl prior to material placement. The materials were stored either for 1 week or 24 weeks in 37°C in fully saturated conditions. Shear bond strength was assessed at both time periods. Radiopacity of the interfacial dentine was also evaluated to assess the remineralization potential of the dentine replacement materials. ResultsThe reaction of Theracal was slower than that of the water-based materials. The bond strengths of different materials did not differ after 1 week (P>0.05). The bond strength of Biodentine and Retro MTA increased over time but no change was observed for Theracal. NaOCl pre-treatment deteriorated the bond strength to sound dentine but improvement was observed in affected dentine. Radiopacity changes were observed after 24 weeks. SignificanceBiodentine and Retro MTA showed better bonding to CAD. Pretreatment with NaOCl improved the bond strength of dentine replacement materials to CAD.

The action of chemical and mechanical stresses on single and dual species biofilm removal of drinking water bacteria

The presence of biofilms in drinking water distribution systems (DWDS) is a global public health concern as they can harbor pathogenic microorganisms. Sodium hypochlorite (NaOCl) is the most commonly used disinfectant for microbial growth control in DWDS. However, its effect on biofilm removal is still unclear. This work aims to evaluate the effects of the combination of chemical (NaOCl) and mechanical stresses on the removal of single and dual species biofilms of two bacteria isolated from DWDS and considered opportunistic, Acinectobacter calcoaceticus and Stenotrophomonas maltophilia. A rotating cylinder reactor was successfully used for the first time in drinking water biofilm studies with polyvinyl chloride as substratum. The single and dual species biofilms presented different characteristics in terms of metabolic activity, mass, density, thickness and content of proteins and polysaccharides. Their complete removal was not achieved even when a high NaOCl concentrations and an increasing series of shear stresses (from 2 to 23Pa) were applied. In general, NaOCl pre-treatment did not improve the impact of mechanical stress on biofilm removal. Dual species biofilms were colonized mostly by S. maltophilia and were more susceptible to chemical and mechanical stresses than these single species. The most efficient treatment (93% biofilm removal) was the combination of NaOCl at 175mg·l−1 with mechanical stress against dual species biofilms. Of concern was the high tolerance of S. maltophilia to chemical and mechanical stresses in both single and dual species biofilms. The overall results demonstrate the inefficacy of NaOCl on biofilm removal even when combined with high shear stresses.

Shear bond strength of one-step self-etch adhesives to dentin: Evaluation of NaOCl pretreatment.

BackgroundThe aim of this study was to evaluate the influence of dentin pretreatment with NaOCl on shear bond strength of four one-step self-etch adhesives with different pH values.Material and MethodsBovine permanent incisors were used. Four one-step self-etch adhesives were tested: Adper™ Easy Bond, Futurabond NR, G-aenial Bond, Clearfil S3 Bond. One two-step self-etch adhesive (Clearfil SE Bond) was used as control. Group 1- no pretreatment; group 2- pretratment with 5,25 % NaOCl; group 3- pretreatment with 37 % H3PO4 etching and 5,25 % NaOCl. A hybrid composite resin was inserted into the dentin surface. The specimens were tested in a universal testing machine. The examiners evaluated the fractured surfaces in optical microscope to determine failure modes, quantified with adhesive remnant index (ARI).ResultsDentin pretreatment variably influenced bond strength values of the different adhesive systems. When no dentin pretreatment was applied, no significant differences were found (P >.05) among four adhesives tested. No significant differences were recorded when comparing NaOCl pretreatment with H3PO4 + NaOCl pretreatment for all adhesive tested (P >.05) except Clearfil S3 Bond that showed higher shear bond strength values when H3PO4 was applied. Frequencies of ARI scores were calculated.ConclusionsThe influence of dentin pretreatment with NaOCl depends on the composition of each adhesive system used. There was no difference in bond strength values among self-etch adhesives with different pH values. Key words:Dentin, pretreatment, self-etch adhesives.

Adhesion to enamel of teeth affected by molar incisor hypomineralization: Literature review

Background/Aim: Molar incisor hypomineralization (MIH) is a qualitative defect of systemic origin, affecting permanent first molars and often permanent incisors. The treatment modalities can include, amongst others, fissure sealants for prevention of dental caries and composite restorations. Both require adhesion to tooth structure. The aim of this study was to review the literature on the adhesion to enamel affected by MIH. Material and Methods: A search of PupMed/Medline, Research Gate and Google Scholar was performed and limited between 2003, when the judgement criteria for MIH were set, and 2016. Thirty-three papers were considered relevant to the subject including five in vivo and six in vitro studies. Studies involving less than ten teeth were excluded. Results: A fouryear clinical trial showed that the application of a total-etch 2-step adhesive system prior to sealant placement is superior to the etch-seal technique. Despite the high success rate of composite restorations shown in three clinical longitudinal studies, there are conflicting results over self-etch being superior to total etch adhesive systems. Pretreating the enamel surface, prior to the adhesive system, with fluoride preventive solutions could reduce the mikroleakage under orthodontic brackets. Three in vitro studies provide inconsistent data about NaOCl pretreating potentials to improve adhesion of composite restorations. Resin infiltration, prior to resin restorations, could improve the microhardness of defected enamel, which may lead to increased bond strength, especially in combination with NaOCl pretreatment. Conclusions: Adhesion to enamel affected by molar incisor hypomeralization is inferior compared to normal enamel. Sealants applied with the etch-bondseal technique have greater retention than with the etch-seal technique. Further research is required to provide evidence of the effectiveness of the adhesive system and pretreatment to achieve optimal bonding to MIH.

EDTA Treatment for Sodium Hypochlorite–treated Dentin Recovers Disturbed Attachment and Induces Differentiation of Mouse Dental Papilla Cells

IntroductionThe disturbance of cellular attachment to dentin by sodium hypochlorite (NaOCl) may hamper pulp tissue regeneration. The aims of this study were to examine the recovering effect of EDTA on the attachment/differentiation of stemlike cells and to address the mechanisms of EDTA-induced recovery under the hypothesis that attachment to the exposed dentin matrix and the subsequent activation of integrin/phosphatidylinositol 3-kinase (PI3K) signaling play a crucial role. MethodsMouse dental papilla (MDP) cells were cultured on bovine dentin disks treated with NaOCl (0%, 1.5%, or 6%) followed by EDTA (0%, 3%, or 17%). Cell attachment was evaluated by cell density, viability, and scanning and transmission electron microscopy. Odonto-/osteoblastic gene expression in attached MDP cells was analyzed with or without a pan-PI3K inhibitor (LY294002) using real-time polymerase chain reaction. ResultsNaOCl treatment (1.5%, 10 minutes) significantly diminished attached MDP cells (P < .00001), but EDTA treatment (3% and 17%, ≥10 minutes) of NaOCl-pretreated dentin induced a significant increase in attached cells (P < .05). Ultrastructurally, MDP cells on EDTA-treated dentin showed attachment to exposed collagen fibers. MDP cells cultured on EDTA-treated disks (with or without 1.5% NaOCl pretreatment) showed significant up-regulation of alkaline phosphatase, dentin matrix protein 1, and dentin sialophosphoprotein messenger RNAs (P < .05). Alkaline phosphatase expression was down-regulated by LY294002 (P < .05). ConclusionsUnder the present experimental conditions, 10 minutes of EDTA treatment was sufficient to recover attachment/differentiation of MDP cells on 1.5% NaOCl-pretreated dentin. EDTA-induced exposure of collagen fibers and subsequent activation of integrin/PI3K signaling may contribute, at least partly, to the recovery.

Effects of Epigallocatechin-3-gallate (EGCG) on the bond strength of fiber posts to Sodium hypochlorite (NaOCl) treated intraradicular dentin

This study was to evaluate the effect of Epigallocatechin-3-gallate (EGCG) on the bond strength of two adhesive systems to the Sodium hypochlorite (NaOCl) treated intraradicular dentin. The roots were accepted regular root canal treatments and post space preparations, and further divided into eight groups according to the four post space pretreatments and two dentin adhesives [Single Bond 2 (SB2) and Clearfil SE Bond (CSB)] used. The push-out strength before and after thermocycling in different root region (coronal and apical), DC of the adhesive and morphologic patterns of treated post space were evaluated. NaOCl + EGCG groups showed the highest push-out strength regardless of the adhesive type, root region and time (P < 0.05). NaOCl pretreatment significantly decreased the push-out strengths and DC of CSB (P < 0.05). EGCG could improve the bonding properties of both SB2 and CSB to NaOCl treated intraradicular dentin. The effect of NaOCl on bonding of a fiber post depended on the type of the adhesive.

NaOCl pretreatment and 3-year retention of cervical composite restorations

NaOCl pretreatment and 3-year retention of cervical composite restorations

Analysis of Conveyance Environment and Pre-treatment on Quality Maintenance of Cut Dendranthema grandiflorum ‘Baekma’ during Ship Export to Japan

본 연구는 절화 국화 'Baekma'를 일본으로 선박 수출 시 수송 환경을 분석하였으며, 절화 국화의 선도를 유지하기 위한 최적 전처리제를 구명하고자 하였다. 그 결과 일본으로 절화 국화를 수출시 약 3일~5일이 소요되었으며, 국내 이동, 선박 운송 및 일본 내에서 이동은 저온이 유지되었으나, 일본에서 검역시 상온에 노출되는 것으로 조사되었다. 이는 품질의 손상을 야기하는 것으로 수송 전체 기간동안 저온조건을 유지해야 할 것으로 판단되었다. 또한, 전처리제는 Chrysal RVB, NaOCl 처리구가 절화수명 연장에 효과적이었으며, Chrysal RVB 전처리는 절화 국화가 끝까지 만개하여 화형이 유지되었다. 박테리아 검정 결과 NaOCl, <TEX>$ClO_2$</TEX> 처리구의 박테리아가 검출되지 않아 살균 성분이 세균증식을 막아준 것으로 판단되었다. 그러나 <TEX>$ClO_2$</TEX>처리구는 수확 후 초기 생육에 영향을 미치는 것으로 사료되었다. Chrysal RVB 처리 및 NaOCl 처리구의 엽록소 함유량이 가장 높은 것으로 조사되었다. This study was carried out to investigate conveyance environment during shipping export to Japan and the optimum pre-treatment of cut Dendranthema grandiflorum 'Baekma'. Shipping from Korea to Japan, which usually takes three to five days, requires keeping the flower at the ideal temperature. When inspection took place in Japan, the ideal temperature was lost and deterioration began. Once the ideal temperature is lost, deterioration takes place. The results of this work showed that vase life was extended by treatment Chrysal RVB and NaOCl compared to the control (distilled water), and Chrysal RVB was used to maintain the flower from bud to full bloom. Bacterial growth was not observed after pretreatment with NaOCl or <TEX>$ClO_2$</TEX>. However, <TEX>$ClO_2$</TEX> pre-treatment was observed to affect the early growth period of the bacteria. The chlorophyll content was the highest after Chrysal RVB or NaOCl pretreatment compared to the other treatments. Therefore, these results support pretreatment with NaOCl and Chrysal RVB of Dendranthema grandiflorum 'Baekma' for export to Japan.

The effects of sodium hypochlorite and chlorhexidine irrigants on the antibacterial activities of alkaline media against Enterococcus faecalis

ObjectiveSodium hypochlorite (NaOCl), chlorhexidine (CHX) and calcium hydroxide are common intracanal medicaments. The present study aimed to evaluate the effects of NaOCl and CHX on the antibacterial activities of alkaline media against Enterococcus faecalis. DesignsThe survival rates of planktonic and biofilm E. faecalis were evaluated by plate counts after 1min of pretreatment with NaOCl and CHX, and time-kill assays were then used to assess subsequent pH alkaline challenges. Dead and living cells in the E. faecalis biofilm were assessed with SYTO 9 and PI staining in combination with confocal laser scanning microscopy following exposure to NaOCl or CHX and subsequent alkaline challenges by common root canal irrigation and dressing procedures. ResultsOne minute of pretreatment with 2% CHX, 0.2% CHX, or 5.25% NaOCl in combination with a subsequent alkaline challenge significantly decreased planktonic E. faecalis survival rates, but pretreatment with 1% NaOCl did not. The E. faecalis biofilm survival rates were reduced in the subsequent alkaline challenge following CHX pretreatment but gradually increased following NaOCl pretreatment. Similarly, CLSM analysis revealed that the greatest proportions of dead E. faecalis cells in the biofilms were presented in the CHX and alkaline treatment group. ConclusionCHX might be more effective in improving the antibacterial activities of alkaline root canal medicaments against E. faecalis than NaOCl during routine root canal therapy procedures.

NaOCl-mediated biofunctionalization enhances bone-titanium integration.

The aim of this study was to examine the effect of NaOCl pretreatment on the biomechanical fixation of implant at the early healing stage of a rat model. Polished titanium cylindrical implants and disks were prepared, and one-half of these samples were dual acidetched. Then, one-half of both surfaces were chemically-cleaned by pretreatment with 5% NaOCl solution for 24 h. Morphological analyses showed that there was no significant difference between before and after NaOCl treatment. The wettability measurement demonstrated that NaOCl treatment secondarily converted both titanium surfaces from hydrophobic to superhydrophilic, accompanied by the removal of hydrocarbons from the titanium surfaces. Biomechanical push-in test indicated that the bone-titanium integration strength of the NaOCl-treated implants were significantly greater than that of the untreated implants (p<0.05). These results showed that NaOCl pretreatment enhanced the osseointegration capability of titanium, indicating its potential for a simple chemical chair-side pretreatment method.

Immediate Shear Bond Strength of Resin Cements to Sodium Hypochlorite–treated Dentin

IntroductionThe purpose of this in vitro study was to evaluate the immediate shear bond strength of different categories of resin cements on sodium hypochlorite (NaOCl)-treated dentin and to evaluate if the bond was improved by a subsequent treatment with 10% sodium ascorbate before adhesive procedures. MethodsThis study tested immediate shear bond strengths to human dentin of 5 resin cements: Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein), Multilink (Ivoclar Vivadent), Clearfil Esthetic Cement EX (Kuraray, Tokyo, Japan), SpeedCEM (Ivoclar Vivadent), and Clearfil SA Cement (Kuraray). All cements were tested with no NaOCl pretreatment of the dentin (negative control) and with a 20-minute exposure of the dentin to 6% NaOCl before bonding procedures. The cements found to have decreased bond strengths to NaOCl-treated dentin were tested with the dentin exposed to 10% sodium ascorbate after NaOCl exposure. The sodium ascorbate exposure times tested were 5 seconds and 1 minute. ResultsThe mean and standard deviation values for immediate shear bond strength (MPa) for the negative control group were as follows: Variolink II, 18.8 ± 4.2; Multilink, 29.1 ± 7.1; Clearfil Esthetic Cement EX, 20.7 ± 4.9; SpeedCEM, 17.8 ± 4.2; and Clearfil SA Cement, 7.2 ± 2.8. The results for the NaOCl exposure group were as follows: Variolink II, 24.0 ± 6.7; Multilink, 34.1 ± 6.1; Clearfil Esthetic Cement EX, 20.7 ± 6.8; SpeedCEM, 0.0 ± 0.0; and Clearfil SA Cement, 0.1 ± 0.1. The results for the 5-second sodium ascorbate group were the following: SpeedCEM, 8.5 ± 2.6, and Clearfil SA Cement, 4.3 ± 2.0. The following results were found for the 1-minute sodium ascorbate group: SpeedCEM, 12.2 ± 3.2, and Clearfil SA Cement, 4.8 ± 1.0. ConclusionsThe resin cements tested varied in their capacity to adhere to NaOCl-treated dentin. Some resin cements exhibited equal or improved bond strengths (P < .05), whereas others exhibited significantly decreased bond strengths (P < .05). For the susceptible resin cements, a rinse of 10% sodium ascorbate provided an immediate restoration of at least 50% of the original bond strength (P < .05). The efficacy of sodium ascorbate may vary among resin cements.

Mineralisation of Developmentally Hypomineralised Human Enamel in vitro

Molar-incisor hypomineralisation (MIH) is a problematic and costly condition. Caries remineralising agents are often recommended for MIH management despite the lack of evidence that these lesions have the capacity for increasing their mineral content. Following surface layer removal ± NaOCl pre-treatment and 14-day exposure to a CPP-ACFP solution at pH 5.5, MIH lesions were analysed using transverse microradiography and polarised light microscopy. Lesions were highly variable but treatment with the remineralising solution increased mineral content (1,828 ± 461 vol% min·µm, %R = 17.7 ± 5.7) and porosity decreased demonstrating the proof of concept that the mineral content of developmentally hypomineralised enamel can be improved after eruption.

Effect of different adhesion strategies on fiber post cementation: Push-out test and scanning electron microscopy analysis

Aim:The aim of this study was to investigate the effect of phosphoric acid etching and the dentin pre-treatment with sodium hypochlorite (NaOCl) on the push-out bond strength between fiber post and root canal dentin.Materials and Methods:Root canals of 48 human incisors were selected, post spaces were prepared and assigned to four groups: G1-37% phosphoric acid (15 s); G2-5.25% NaOCl (2 min) +37% phosphoric acid (15 s); G3-37% phosphoric acid (60 s); and G4-5.25% NaOCl (2 min) +37% phosphoric acid (60 s). Fiber post cementation was performed with two-step etch-and-rinse adhesive system/dual-cured resin cement according to the manufacturer's recommendation. After 24 h, each root was sectioned transversally into three slices (cervical, middle and apical) and the bond strength of each section was determined using a push-out bond strength test. Morphology analysis of the bonded interface was evaluated using a scanning electron microscopy. Push-out strength data (MPa) were analyzed by Analysis of Variance and Tukey-Kramer (α = 0.05).Results:Considering the NaOCl pre-treatment, no statistically significant differences were observed among groups; however, when the phosphoric acid was applied during 60 s in the apical portion without NaOCl pre-treatment, the bond strength was statistically significant increased.Conclusion:The NaOCl pre-treatment did not improve the bond strength of adhesive luting cement to root canal dentin. The findings suggest that the use of 37% phosphoric acid for 60 s may have a beneficial effect on bond strength in the apical root third.

Effect of dentin pretreatment with mild acidic HOCl solution on microtensile bond strength and surface pH

Objectives To evaluate the pretreatment effect of mild acidic HOCl solution on the microtensile bond strength (μTBS) of a two-step self-etch adhesive to dentin and the alteration of dentin surface pH. Methods Thirty-nine flat ground coronal dentin specimens were divided into one control group and 12 experimental groups, which were treated with 6% NaOCl or 50, 100 and 200 ppm HOCl (Comfosy ®) solutions for 5, 15 and 30 s. After rinsing with running water for 30 s, all the dentin surfaces were bonded with Clearfil SE Bond according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were sectioned and trimmed to an hourglass shape with a cross-sectional area of approximately 1.0 mm 2 and then subjected to the μTBS test. Thirty-six mid-coronal dentin discs were used for surface pH measurement. Dentin surface pH with or without pretreatment was examined using a pH-imaging microscope (SCHEM-100). The μTBS data were analyzed by one-way ANOVA (Dunnett's T3) and the surface pH data were analyzed by non-parametric statistics (Mann–Whitney U-test). Results Pretreatment with Comfosy ® at concentrations of 50, 100 and 200 ppm did not significantly affect μTBS regardless of the application time compared with the control group, however the 100 and 200 ppm Comfosy ® groups showed significantly lower surface pH values. For the NaOCl pretreatment groups, a longer application time significantly decreased the μTBS and increased the surface pH values compared to the control group. Conclusions The 50 ppm Comfosy ® pretreatments for 5, 15 and 30 s did not affect the μTBS of the two-step self-etch adhesive to dentin and dentin surface pH.

Improving the effect of NaOCl pretreatment on bonding to caries-affected dentin using self-etch adhesives

Objective To evaluate the effect of sodium hypochlorite pretreatment on adhesion to normal and caries-affected dentin using self-etch adhesives. Methods Forty extracted human molars with coronal carious lesions were used in this experiment. The occlusal dentin surfaces including the caries-affected dentin in each group were treated as follows: group 1, rinsed with water; group 2, treated with 6% NaOCl for 15 s; group 3, treated with 6% NaOCl for 30 s; group 4, application with Accel for 30 s after NaOCl-30 s pretreatment. After rinsing with water and air-drying, the treated dentin surfaces were applied with self-etch systems (Bond Force and Clearfil Protect Bond) according to the manufacturers’ instructions, and built-up with resin composite. After 37 °C water storage for 24 h, the bonded normal or caries-affected dentin areas were isolated to create an hourglass configuration with a cross-sectional area of approximately 1 mm 2. The specimens were subjected to tensile stress at a cross-head speed of 1.0 mm/min. Results NaOCl-15 s pretreatment significantly improved the μTBS of both self-etch adhesives to caries-affected dentin, while the 30 s pretreatment did not affect them. For normal dentin, NaOCl-30 s pretreatment significantly reduced the μTBS of both self-etch adhesives although the 15 s pretreatment did not alter them. Furthermore, the application of Accel with a reducing effect increased the μTBS to normal and caries-affected dentin treated with NaOCl for 30 s. Conclusions The effects of NaOCl pretreatment on bonding of both self-etch adhesives were dependent upon type of dentin (normal and caries-affected dentin) and the treatment time.