Penetration of sodium hypochlorite into root canal dentine: effect of surfactants, gel form and passive ultrasonic irrigation.

AIM: To assess the penetration of sodium hypochlorite (NaOCl) gel or NaOCl solutions with surfactants, and the effect of passive ultrasonic irrigation (PUI) on penetration into dentinal tubules. METHODOLOGY: Bovine incisor root canals were instrumented, the roots sectioned and the dentine blocks obtained were stained with crystal violet. Dentine blocks (n = 10 per group) were exposed to 3% NaOCl gel or 3% NaOCl solution for 10 and 20 min. Other dentine blocks (n = 10 per group) were exposed to Chlor-Extra (6% NaOCl + surfactant), 6% NaOCl, 2.5% NaOCl with 0.2% cetrimide and 2.5% NaOCl for 10 and 20 min. The penetration depth of irrigants into dentinal tubules was measured in micrometres by viewing the bleached crystal violet under a stereomicroscope. Additionally, bovine incisor root canals, instrumented and stained with crystal violet, were distributed into two groups (n = 10) and irrigated with 2.5% NaOCl with PUI or conventional syringe irrigation (CSI). The penetration depth of irrigants into dentinal tubules was assessed 3 and 7 mm from the apex. Statistical analysis was performed by ANOVA and Tukey tests (α = 0.05). RESULTS: There was significantly greater penetration of 3% NaOCl solution into dentinal tubules compared with the gel form (P < 0.05). There was no difference (P > 0.05) between 6% NaOCl and Chlor-Extra, and between 2.5% NaOCl and 2.5% NaOCl + cetrimide. PUI significantly increased the penetration depth of NaOCl into dentinal tubules when compared with CSI (P < 0.05). CONCLUSIONS: In extracted bovine incisors, NaOCl gel penetrated less into dentinal tubules than NaOCl solution. The addition of surfactants did not increase the penetration depth. The use of PUI significantly increased NaOCl penetration into dentinal tubules.

Sodium hypochlorite penetration into dentinal tubules after manual dynamic agitation and ultrasonic activation: a histochemical evaluation.

The aim of this study was to compare the effects of Manual Dynamic Agitation and Passive Ultrasonic Irrigation on sodium hypochlorite (NaOCl) penetration into dentinal tubules using its bleaching ability. Thirty-four single-rooted teeth with round-shaped root canals were distributed in two homogeneous groups and one control group, characterized by different NaOCl activation systems: Manual Dynamic Agitation and Passive Ultrasonic Irrigation. After instrumentation, all root canals were stained with 10% copper sulphate solution followed by 1% rubeanic acid alcohol solution under vacuum. Final irrigation was performed with 5 mL of 5.25% NaOCl solution for 1 min and activated with Manual Dynamic Agitation or Passive Ultrasonic Irrigation for another 1 min depending on the treatment group. The teeth were transversely sectioned at the middle portion of the apical, middle, and coronal thirds and observed under light microscope. NaOCl solution penetration was evaluated by measuring the percentage of bleached circumference of the root canal relative to the stained circumference, bleached areas, mean, and maximum penetration depth. No differences in the evaluated parameters were observed between groups (p > 0.05). Within groups, an increase of values was recorded from apical to coronal direction as for percentage of staining, percentage of bleaching and bleached area. NaOCl penetration into dentinal tubules did not significantly vary among the three levels. No significant differences in penetration of sodium hypochlorite into dentinal tubules when activated by means of Manual Dynamic Agitation or Passive Ultrasonic Irrigation were observed in the apical, middle, and coronal thirds of teeth with single straight round root canals.

Sodium hypochlorite solution penetration into human dentine: a histochemical evaluation.

AIM: The aim of this study was to evaluate ex vivo the penetration depth of sodium hypochlorite solutions, with and without surfactants, into human dentine using a histochemical stain and the bleaching ability of NaOCl. METHODOLOGY: Extracted maxillary central incisors were decoronated and their root canals were shaped to a size 30, .07 taper. Dentinal tubules were stained with 10% copper sulphate solution followed by a 1% rubeanic acid alcohol solution under vacuum. Specimens were irrigated with 5 mL of Niclor 5 (5.25% NaOCl solution) or 5 mL of Hypoclean (5.25% NaOCl solution + surfactants) according to the corresponding treatment group, for 2 min. A transverse section was obtained in the middle portion of the apical, middle and coronal thirds of each tooth. Under microscopic examination, irrigant penetration was evaluated by measuring the following: the bleached circumference of the root canal with respect to the stained circumference; bleached areas, mean and maximum penetration depth. For statistical analysis, Pearson's chi-squared test and one-way anova were used. RESULTS: Only 30% of dentine tubules in the apical portions were stained; therefore, these were excluded from further comparisons. In the middle and coronal thirds, the average bleached circumference of the root canal was 80-99% of the stained circumference and the bleached area was 73757-135107 µm2 . The average penetration depth ranged from 39 to 62 µm and maximum penetration from 74 to 131 µm. For all reported results, no differences within and between groups were observed (P = 1). CONCLUSION: No differences in penetration of irrigants with and without surfactants into dentinal tubules were observed in the middle and coronal thirds of incisor teeth.

Application of 17% EDTA Enhances Diffusion of (45)Ca-labeled OH(-) and Ca(2+) in Primary Tooth Root Canal.

Proper cleaning of the root canal is key to the success of endodontic treatment as it allows more effective diffusion of medication throughout the dentinal tubules. The aim of this in vitro study was to investigate the efficacy of 17% ethylenediaminetetraacetic acid (EDTA) in enhancing diffusion of hydroxyl (OH(-)) and calcium ions (Ca(2+)) throughout the root canal in primary teeth. The canals of 25 primary tooth roots were cleaned with endodontic files and 1% sodium hypochlorite. Three groups (G) were then established: GI, in which final irrigation was performed with 1% sodium hypochlorite; GII, in which 17% EDTA was used; and GIII, in which no irrigation was performed. The roots canals in GI and GII were filled with a calcium hydroxide-based paste labeled with the radioisotope calcium-45. Diffusion of OH(-) was detected with pH strips and Ca(2+) analyzed by measuring radioactivity in counts per min. Group II differed statistically from the other groups in diffusion of OH(-) at 24 hr (p<0.05), but no significant difference among groups was found at the day 7 evaluation; GII also differed statistically from the other groups in diffusion of Ca(2+) at 24 hr (p<0.05). These results suggest that application of 17% EDTA in primary tooth enhances diffusion of OH(-) and Ca(2+).

Comparison of irrigant penetration up to working length and into simulated lateral canals using various irrigating techniques.

AIM: To evaluate the effect of an apical negative pressure system, a passive ultrasonic irrigation system and a combination of both apical negative pressure and passive ultrasonic irrigation on the penetration of the irrigating contrast solution (ICS) up to working length and into simulated lateral canals. METHODOLOGY: The root canals of 64 single-rooted teeth were instrumented using the ProTaper rotary system. In each sample, three simulated lateral canals were created at 2, 4 and 6 mm levels from the root apex using a 06-size C+ file (Dentsply Maillefer, Ballaigues, Switzerland). Samples were randomly assigned into 4 experimental groups (n = 16): group I - conventional needle irrigation, group II - passive ultrasonic irrigation, group III - apical negative irrigation system and group IV - combination of passive ultrasonic irrigation and apical negative pressure irrigation system. To examine irrigating solution penetration, Indian ink was mixed with 5.25% NaOCl and delivered into the root canals. Samples were then assessed by direct observation of the images taken using Canon EOS rebel T3. The depth of penetration of ICS up to the working length and into the simulated lateral canals was analysed using chi-squared tests. RESULTS: The combination (ANP and PUI) and ANP group had significantly deeper ICS penetration up to the working length (P < 0.001). The combination (ANP and PUI) and the PUI group exhibited significantly greater ICS penetration into lateral canals at the 6 mm level (P < 0.001). At the 4 and 2 mm levels, the combination of ANP and PUI had significantly greater ICS penetration into the lateral canals than the other groups (P < 0.001). CONCLUSIONS: The combination of ANP and PUI was the only group able to achieve irrigating contrast solution penetration both up to the working length and into lateral canals.

The effect of surface tension reduction on the clinical performance of sodium hypochlorite in endodontics.

Sodium hypochlorite (NaOCl) is recommended as an endodontic irrigant in view of its broad antimicrobial and tissue dissolution capacities. To enhance its penetration into inaccessible areas of root canals and to improve its overall effect, the addition of surface-active agents has been suggested. The aim of this investigation was to review the effect of the reduction of the surface tension on the performance of NaOCl in endodontics. A search was performed in the Medline electronic database (articles published up to 28 July 2012, in English) with the search terms and combinations as follows: 'sodium hypochlorite AND surface tension or interfacial force or interfacial tension or surface-active agent or amphiphilic agent or surface active agent or surfactant or tenside or detergent'. The purpose of this search was to identify publications that compared NaOCl alone and NaOCl modified with the addition of a surface-active agent in endodontics. A hand search of articles published online ('in-press' and 'early view'), and appearing in the reference list of the articles included, was further performed, using the same search criteria as the electronic search. The search identified 302 publications, of which 11 fulfilled the inclusion/exclusion criteria of the review. The evidence available suggests that surface-active agents improve the penetration of NaOCl in the main canal and have no effect on its pulp tissue dissolution ability. There are, however, insufficient data to enable a sound conclusion to be drawn regarding the effect of modifying NaOCl's surface tension on lubrication, antimicrobial and smear layer or debris removal abilities.

Reaction rate of NaOCl in contact with bovine dentine: effect of activation, exposure time, concentration and pH.

AIM: To determine the influence of activation method (ultrasound or laser), concentration, pH and exposure time on the reaction rate (RR) of NaOCl when in contact with dentinal walls. METHODOLOGY: The walls from standardized root canals in bovine incisors were exposed to a standardized volume of sodium hypochlorite (NaOCl) with different concentrations (2% and 10%), pH (5 and 12) and exposure times (1 and 4min). Two irrigation protocols were tested: passive ultrasonic irrigation or laser activated irrigation with no activation as the control. The activation interval lasted 1min followed by a rest interval of 3 min with no activation. The RR was determined by measuring the iodine concentration using an iodine/thiosulfate titration method. RESULTS: Exposure time, concentration and activation method influenced the reaction rate of NaOCl whereas pH did not. CONCLUSIONS: Activation is a strong modulator of the reaction rate of NaOCl. During the rest interval of 3min, the consumption of available chlorine increased significantly. This effect seems to be more pronounced after irrigant activation by laser. pH did not affect the reaction rate of 2% NaOCl.

Penetration of hypochlorites with lowered surface tension into dentine tubules.

BACKGROUND: The purpose of the present study was to assess the effect of concentration and temperature of sodium hypochlorite (NaOCl) with added surfactants and time of exposure on its penetration into human dentine. METHODS: Seventy-five extracted permanent maxillary anterior teeth with single canals were shaped by using ProTaper SX hand-operated instruments. Then teeth were sectioned perpendicular to their long axis. The crowns and apical thirds of all the teeth were removed. The remaining roots were processed into 4-mm-long blocks and stained overnight in crystal violet. One hundred fifty stained blocks were further split into halves and treated by six NaOCl-based solutions from different brands: three solutions added with surfactants (Hypoclean, H6, Chlor-Xtra) and their regular counterparts (5.25%, 6%, <%6NaOCl). The dentine blocks were exposed to the solutions for 2, 5, and 20 minutes at 20° C, 37° C, and 45° C, respectively. The depth of penetration of NaOCl was determined by bleaching of the stain and measured by light microscopy at magnifications of 20x and 40x. Statistical analysis was made by using two way ANOVA and by comparing groups two by two with t-test. RESULTS: The shortest penetration (130.80±1.92µm) was measured after incubation with 5.25%NaOCl for 2 minutes at 20° C; the highest penetration (375.40±3.05µm) was obtained with Chlor-Xtra for 20 minutes at 45° C. Temperature and exposure time had a significant direct relationship with penetration of sodium hypochlorites with lowered surface tension into dentinal tubules. CONCLUSIONS: The exposure time and temperature of sodium hypochlorite as well as the addition of surfactants may influence the penetration depth of irrigants into dentinal tubules.

Penetration into dentin of sodium hypochlorite associated with acid solutions.

OBJECTIVE: The objective of this study was to evaluate the penetration of 2.5% NaOCl associated with 17.0% EDTA, 1.0% citric acid, and 1.0% peracetic acid into dentin tubules. STUDY DESIGN: The roots of 44 bovine incisors were cross-sectioned and 5-mm-long fragments were produced from their middle thirds. The specimens were instrumented with ProTaper hand files, stained in crystal violet, then sectioned mesiodistally. The buccal fragments were divided into 4 groups (n = 9) and subjected to 2 consecutive 10-minute immersion periods in one of the following acid solutions combined with 2.5% NaOCl: 17.0% EDTA (group 1), 1.0% citric acid (group 2), and 1.0% peracetic acid (group 3). Nine fragments were immersed in 2.5% NaOCl (group 4). The analysis of the penetration of NaOCl solutions into dentin was performed by measuring the depth of crystal violet stain that was bleached using a steromicroscope under ×50 magnification. Statistical comparisons were carried out by Kruskal-Wallis and Dunn's tests at the 5% significance level. RESULTS: Group 1 showed less penetration into dentin than group 4 (P < .05). No statistically significant differences were observed among groups 2, 3, and 4 (P > .05). CONCLUSIONS: Association of NaOCl with acid solutions did not increase its penetration depth into root dentin.

[Capacity of hypochlorite to penetrate into the lipid phase of human blood lipoproteins]. / Izuchenie sposobnosti gipokhlorita pronikat' v lipidnuiu fazy lipoproteinov krovi cheloveka.

In order to elucidate the possibility of hypochlorite (NaOCl) presenting in aqueous media to penetrate into the surface proteolipid layer of low density lipoproteins (LDL), the kinetics of NaOCl-induced oxidation of spin probes localized within the lipid phase was studied. The paramagnetic analogs of stearic acid were employed as spin probes that contained doxyl groups localized at different positions on the carbon chain (at positions 5, 13 and 16). It was shown that all the three probes are oxidated by hypochlorite with the same rate both in aqueous media and in LDL. The results obtained indicate that hypochlorite in water may interact with groups in the lipid phase of LDL, including unsaturated--HC = CH--bonds.

Análise pela microscopia eletrônica de varredura da limpeza das paredes dos canais radiculares segundo as substâncias irrigadoras de acordo com três diferentes técnicas / Analisys through the scanning electron microscopy of root canals walls cleaning as to the irrigation substances in accordance with three differents techniques

Buscou-se verificar in vitro a remoçäo de restos pulpares e magma dentinário das paredes dos canais radiculares, quando do emprego na irrigaçäo final de substâncias químicas segundo três diferentes técnicas. No P.Q.C. utilizou-se a técnica telescópica e hipoclorito de sódio a 1 por cento. A irrigaçäo final foi de 30 ml: Grupo I - 10ml de hipoclorito de sódio a 1 por cento + 10 ml de ácido cítrico a 10 por cento + 10ml de água destilada; Grupo II - 15ml de hipoclorito de sódio a 0,5 por cento + 15 ml de EDTA-T; Grupo III - 10 ml de hipoclorito de sódio a 5 por cento + 10 ml de água oxigenada a 3 por cento + 10 ml de hipoclorito de sódio a 5 por cento. A avaliaçäo pelo MEV fez-se pela média da leitura dos túbulos dentinários visíveis segundo 3 observadores de uma fotomicrografia de cada terço...