The solvent effects of calcium hydroxide irrigating solution on bovine pulp tissue

Calcium Hypochlorite Solutions - An In Vitro Evaluation of Antimicrobial Action and Pulp Dissolution

Objective:

To compare the antimicrobial activity and tissue dissolution capacity of calcium hypochlorite (Ca(OCl)₂) solution with sodium hypochlorite (NaOCl) solution at 0.5%, 1.0%, 2.5%, and 5.25% concentrations.

Methods:

To determine the inhibition halos produced by the tested substances against Enterococcus faecalis, the agar diffusion method was employed. Additionally, the broth contact method was used to determine the time required for the inhibition of E. faecalis. Bovine pulp fragments were used to test the dissolution. Half of the pulps were freely deposited samples in cell culture wells, and the remaining samples were fixed on bovine dentine bases.

Results:

For both Ca(OCl)₂ and NaOCl solutions, the greatest inhibition zones were observed at 5.25% con-centration. However, the most significant inhibition zone was measured with 5.25% Ca(OCl)₂ solution (17.38 mm). Hypochlorite solutions at 2.5% and 5.25% concentrations required less time to inhibit E. faecalis than those at 0.5% and 1.0% concentrations (P<0.05). There was no difference in inhibition times between 2.5% and 5.25% hypochlorite solutions (P>0.05). The most effective hypochlorite solution concentrations were 5.25% and 2.5% for dissolving pulp fragments (P<0.05). Additionally, suspended pulp fragments were more susceptible to dissolution than fragments attached to dentine blocks (P<0.05), except for 0.5% Ca(OCl)₂.

Conclusion:

Ca(OCl)₂ solutions showed antimicrobial activity against E. faecalis and can dissolve pulp tissues. Future studies are warranted to examine the suitability of Ca(OCl)₂ in the chemico–mechanical preparation of the root canal system.

A Review Over Benefits and Drawbacks of Combining Sodium Hypochlorite with Other Endodontic Materials

INTRODUCTION

As the root canal system considered to be complex and unpredictable, using root canal irrigants and medicaments are essential in order to enhance the disinfection of the canal. Sodium hypochlorite is the most common irrigant in endodontics. Despite its excellent antimicrobial activity and tissue solubility, sodium hypochlorite lacks some important properties such as substantivity and smear layer removing ability.

OBJECTIVE

The aim of this review was to address benefits and drawbacks of combining sodium hypochlorite with other root canal irrigants and medicaments.

DISCUSSION

According to the reviewed articles, NaOCl is the most common irrigation solution in endodontics. However, it has some drawbacks such as inability to remove smear layer. One of the drawbacks of NaOCl is its inability to remove the smear layer and lack of substantivity.

CONCLUSION

The adjunctive use of other materials has been suggested to improve NaOCl efficacy. Nevertheless, further studies are required in this field.

[Efficacy of sodium hydroxide at 2.5 %, chlorhexidine gluconate at 0.5 % and calcium hydroxide against Candida albicans]

INTRODUCTION

Endodontic flora is dominated in the apical part of the channels by strict anaerobic and some facultative anaerobic bacteria but also by Candida yeasts, especially Candida albicans species that are involved in the maintenance and persistence of endodontic infections. Their elimination of the canal system in practice by chemo-mechanical methods of disinfection is not always guaranteed. Thus, this in vitro study was performed to determine the sensitivity of C. albicans with sodium hypochlorite (NaOCl) dosed at 2.5 %, the chlorhexidine digluconate 0.5 % and calcium hydroxide used in inter-session medication.

METHODS

The diffusion method was used initially to test the sensitivity of C. albicans strains with the above products. Then a dilution technique has allowed us to determine the minimum inhibitory concentration of these active products on C. albicans.

RESULTS

Strains from infected pulp teeth of patients showed a sensitivity of C. albicans to sodium hypochlorite to a minimum inhibitory concentration less than 70μg/mL and 30μg/mL for chlorhexidine.

CONCLUSION

This study demonstrated a sensitivity of C. albicans to sodium hypochlorite and chlorhexidine.

Avaliação da capacidade de dissolução de tecido pulpar bovino pelo hipoclorito de sódio em diferentes concentrações

ResumoIntroduçãoO hipoclorito de sódio é a substância química auxiliar do tratamento endodôntico mais utilizada devido à sua ação antimicrobiana e à sua capacidade de dissolver matéria orgânica.ObjetivoO objetivo do presente estudo foi comparar a velocidade de dissolução de fragmentos de tecido pulpar bovino em diferentes concentrações de hipoclorito de sódio.Material e métodoFragmentos de tecido pulpar bovino, com peso determinado, foram imersos em 20 mL de hipoclorito de sódio, em frascos de Becker colocados em uma incubadora/agitadora. Foram testadas as concentrações de 1%, 2,5% e 5%, com pH 11, a 36°C. As amostras foram avaliadas visualmente durante a agitação, com auxílio de lupa, até sua completa dissolução. A velocidade de dissolução de cada fragmento foi determinada em miligramas por minuto e a velocidade média de cada grupo, analisada pelos métodos estatísticos de Kruskal-Wallis e Dunn's Multiple.ResultadoHouve diferença estatisticamente significante entre a concentração de 1%, que apresentou a menor velocidade, e as demais.ConclusãoA velocidade de dissolução do hipoclorito de sódio, nas concentrações testadas, se torna mais rápida com o aumento da concentração.

Pulp tissue dissolution capacity of QMix 2in1 irrigation solution

OBJECTIVE

The aim of this study was to evaluate the tissue dissolution efficacy of four root canal irrigation solutions (sodium hypochlorite [NaOCl], chlorhexidine gluconate [CHX], Octenidine [OCT], and QMix 2in1) on bovine pulp tissue.

MATERIALS AND METHODS

Fifty bovine pulp tissue samples, each weighing 6.55 mg, were prepared and randomly divided into four experimental groups and one control group (n = 10) according to the dissolution irrigants used: (1) 5.25% NaOCl group; (2) 2% CHX group; (3) OCT group; (4) QMix 2in1 group; and (5) control group (saline solution). These samples were then placed into special bovine dentin reservoir models and immersed for 1 h with each test solution (0.1 mL of each) at room temperature. The pulp samples were then blotted dry and weighed again. The percentage of weight loss was calculated. Statistically analyzed with one-way analysis of variance and post-hoc Tukey tests (P = 0.05).

RESULTS

Saline solution did not dissolve the bovine pulp tissue. All groups, except OCT, dissolved pulp samples more effectively than the control group (P < 0.05). The highest tissue dissolution was observed in 5.25% NaOCl group (P < 0.05). No statistically significant difference was found between the tissue-dissolving effect between QMix 2in1 and those of 2% CHX.

CONCLUSIONS

Within the limitations of this in vitro study, NaOCl exhibited the best tissue-dissolving effect out of all solutions tested. CHX and QMix 2in1 were able to dissolve pulp tissue but less than NaOCl. OCT and saline solutions could not exhibit significantly tissue-dissolving effectiveness. This study shown that QMix 2in1 has little capacity to dissolve pulp tissue therefore used alone is not sufficient for this purpose.

Treatment options: apexogenesis and apexification

This article will describe requirements for case selection and review the procedures for apexogenesis and apexification in immature permanent teeth. Nonclinical and clinical data will be presented to support the recommendations, and outcomes will be presented from clinical studies. The dental pulp is an ectomesenchymally derived connective tissue with certain unique properties such as being encased in hard tissues, which limits its collateral circulation. The pulp provides a matrix for binding of its cells and provides support allowing communication between the cells. In addition to immune cells, the dental pulp contains odontoblasts, which are specialized cells capable of producing dentin. In the absence of a vital pulp, dentin deposition is arrested. When an immature tooth is affected by caries or trauma, the pulp requires proper management according to the degree of inflammation and its vitality. Maintenance of pulp vitality will allow continued root development along the entire root length. If the pulp is irreversibly inflamed or necrotic, root-end closure procedures are required when the apex has not fully formed.

Properties and applications of calcium hydroxide in endodontics and dental traumatology

Calcium hydroxide has been included within several materials and antimicrobial formulations that are used in a number of treatment modalities in endodontics. These include, inter-appointment intracanal medicaments, pulp-capping agents and root canal sealers. Calcium hydroxide formulations are also used during treatment of root perforations, root fractures and root resorption and have a role in dental traumatology, for example, following tooth avulsion and luxation injuries. The purpose of this paper is to review the properties and clinical applications of calcium hydroxide in endodontics and dental traumatology including its antibacterial activity, antifungal activity, effect on bacterial biofilms, the synergism between calcium hydroxide and other agents, its effects on the properties of dentine, the diffusion of hydroxyl ions through dentine and its toxicity. Pure calcium hydroxide paste has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. Its main actions are achieved through the ionic dissociation of Ca(2+) and OH(-) ions and their effect on vital tissues, the induction of hard-tissue deposition and the antibacterial properties. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. It has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also an effective anti-endotoxin agent. However, its effect on microbial biofilms is controversial.

Cytotoxicity of endodontic irrigants containing calcium hydroxide and sodium lauryl sulphate on fibroblasts derived from mouse L929 cell line

The aim of this study was to evaluate the cytotoxicity of root canal irrigating solutions containing calcium hydroxide and sodium lauryl sulphate on fibroblasts derived from L929 cell line. Saturated calcium hydroxide aqueous solution (CH), sodium lauryl sulphate (SLS) and SLS associated with calcium hydroxide (HCT20) were diluted with sterile distilled water at 50%, 20%, 10% and 5% concentrations. Minimum essential medium (MEM) served as the control group. The cytotoxicity of the solutions was evaluated on L929 mouse fibroblast cell line, at 4 and 24 h of contact time by the 51Cr radiotracer method. Data were compared and statistical inferences were made with the chi-square test. In all analysis, significance level was set at 5%. CH and HCT20 showed toxicity at 50% concentration, while at concentrations lower than 50% these solutions showed cell tolerance. SLS was cytotoxic at all concentrations. In conclusion, the association of calcium hydroxide and SLS (HCT20) combines the beneficial properties of these solutions and was not harmful to the fibroblast cell line, seeming to be a suitable endodontic irrigating solution.

Tissue-dissolution capacity and dentin-disinfecting potential of calcium hydroxide mixed with irrigating solutions

OBJECTIVE

The goal of this study was to compare the tissue-dissolution potential and antibacterial effectiveness of a conventional Ca(OH)(2)/saline paste with equivalent Ca(OH)(2)/NaOCl and Ca(OH)(2)/chlorhexidine digluconate medications.

STUDY DESIGN

Tissue specimens were obtained from freshly dissected pig palates. Tissue pieces of similar form and weight were incubated in air-tight containers with Ca(OH)(2) pastes or solutions proper for up to 7 days. Antimicrobial testing was performed in dentin blocks infected with Enterococcus faecalis. Medicated, sealed dentin specimens were incubated for 1 and 5 days, and bacterial growth was tested at different dentin depths.

RESULTS

Up to day 4, the Ca(OH)(2)/irrigating solution mixtures dissolved tissue more effectively than the conventional Ca(OH)(2)/saline paste. After 7 days, however, no statistically significant differences were found between the saline and hypochlorite mixtures, but the Ca(OH)(2)/chlorhexidine medication was significantly less effective. Dentin block disinfection was quicker and more thorough with the Ca(OH)(2)/chlorhexidine or the Ca(OH)(2)/NaOCl than with the Ca(OH)(2)/saline paste.

CONCLUSION

Ca(OH)(2)/irrigant mixtures under investigation appear more advantageous than the conventional Ca(OH)(2)/saline mixture, and merit further investigation in a clinical study.

Quantitative analysis of the solubilizing action of MTAD, sodium hypochlorite, and EDTA on bovine pulp and dentin

Necrotic bovine pulp and dentin were used in this study as model tissues to represent the organic and inorganic components of the smear layer present in instrumented root canals. The capabilities of endodontic irrigants to dissolve pulverized forms of these tissues were compared. Lyophilized tissue samples were mixed for 2 h at 37 degrees C with MTAD, three concentrations of sodium hypochlorite (NaOCl), 17% EDTA, or isotonic saline. Undissolved tissues were rinsed with water and lyophilized. The change in tissue weight after exposure to an irrigant was measured to quantify solubilization. The results showed that various concentrations of NaOCl removed organic components of pulp and dentin effectively. As pulp solubilizers 5.25% and 2.60% NaOCl were equal (>90%), and 5.25% NaOCl was capable of dissolving virtually the entire organic component of dentin. EDTA was capable of solubilizing inorganic material in dentin and organic material in pulp and likely also in dentin. It dissolved >70% of the dentin and >51% of the pulp. The solubilizing effects of MTAD on pulp and dentin were somewhat similar to those of EDTA. The major difference between the actions of these solutions was a high binding affinity of doxycycline present in MTAD for the dentin.

Effectiveness of intracanal irrigants and medications against the yeast Candida albicans

An in vitro study was conducted to determine the susceptibility of the yeast Candida albicans to various intracanal irrigants and medications. The minimum inhibitory concentration (MIC) of sodium hypochlorite, hydrogen peroxide, chlorhexidine digluconate, and aqueous calcium hydroxide that is required to kill a standardized inoculum of C. albicans was determined. Growth of the yeast was measured by optical density. Sodium hypochlorite, hydrogen peroxide, and chlorhexidine digluconate were effective anticandidal agents with MICs of <10 microgram/ml, 234 microgram/ml, and <0.63 microgram/ml, respectively. Aqueous calcium hydroxide had no activity. A standardized inoculum of C. albicans cells was also placed in direct contact with either calcium hydroxide paste or camphorated para-monochlorophenol (CPMC), and candidal growth was assessed by colony counts on Sabouraud's dextrose agar. Calcium hydroxide paste and CPMC, when maintained in direct contact with C. albicans, were effective antifungal agents.

Effect of exposing dentine to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus

AIM

The aim of this study was to evaluate the effect of sodium hypochlorite (NaOCl) solutions (3%, 5%) and saturated calcium hydroxide (Ca(OH)2) solution, individually and consecutively, on the flexural strength and modulus of elasticity of standardized dentine bars.

METHODOLOGY

Standardized plano-parallel dentine bars (n = 121) were divided into five test groups and one control group. The control group 1 consisted of dentine bars, stored in normal saline until testing. The dentine bars in the five test groups were treated by exposure to the following solutions; group 2--3% NaOCl, 2 h; group 3--5% NaOCl, 2 h; group 4--saturated Ca(OH)2 solution, 1 week; group 5--3% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week; group 6--5% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week. The dentine bars were then loaded to failure in a three-point bend test.

RESULTS

The data revealed a significant (P < 0.001) decrease in the modulus of elasticity and flexural strength of the dentine bars treated with 3% and 5% NaOCl. There was no significant difference in the flexural strength and the modulus of elasticity between the 3% and 5% NaOCl groups. Exposure to Ca(OH)2 significantly (P < 0.001) reduced the flexural strength but had no significant effect on the modulus of elasticity. The groups treated with sodium hypochlorite followed by calcium hydroxide did not have moduli of elasticity and flexural strengths that were significantly different from those treated only with sodium hypochlorite.

CONCLUSIONS

NaOCl (3 & 5%) reduced the modulus of elasticity and flexural strength of dentine. Saturated Ca(OH)2 reduced the flexural strength of dentine but not the modulus of elasticity. Sequential use of NaOCl and Ca(OH)2 has no additional weakening effect.

Delayed apical healing after apexification treatment of non-vital immature tooth: a case report

We report the endodontic treatment of a non-vital permanent immature tooth in which unexpected complications such as exacerbation of apical periodontitis followed by external root resorption occurred after that the initial stages of the healing process were clinically and radiographically evident. After continued treatment stable repair was obtained.

Calcium hydroxide pastes: classification and clinical indications

REVIEW ARTICLE: Calcium hydroxide has been used in endodontology for many years. The aim of this paper is to review the various formulations of calcium hydroxide that have been described, with specific reference to the vehicle used to carry the compound. The requirements for a vehicle are described, and ex vivo and in vivo studies reviewed. Vehicles can be classified into aqueous, viscous and oily, the clinical properties of calcium hydroxide changing depending on the vehicle. The review also describes the use of various active components that have been added to calcium hydroxide, including antimicrobial and anti-inflammatory agents. This review will help clinicians to make informed judgements about which formulations of calcium hydroxide should be used for specific endodontic procedures.

The effects of sodium hypochlorite and calcium hydroxide on tissue dissolution and root canal cleanliness

In this in vitro study, we investigated the efficacy of sodium hypochlorite (NaOCl) and calcium hydroxide (Ca(OH)2) in dissolving necrotic tissue and cleaning root canals. In the first part of the study, 0.5% NaOCl solution and Ca(OH)2 paste and solution were tested with samples of necrotic bovine muscle in different treatment modes and for different periods. The necrotic tissue was weighed before and after the test and the percentage of weight change calculated. In the second part of the study, 40 extracted single-rooted human teeth were hand instrumented and then subjected to different irrigation regimens. The cleansing efficacy in root canals of 0.5% NaOCl with Ca(OH)2 pretreatments and ultrasonics was examined using scanning electron microscopy. A solution of 5% NaOCl was significantly more effective than 0.5% NaOCl as a solvent of necrotic tissue. Calcium hydroxide was an effective solvent for necrotic tissue as a paste but not as a solution. Pretreatment of necrotic tissue with Ca(OH)2 increased its solubility in 0.5% NaOCl. While 5% NaOCl plus ultrasonic irrigation produced cleaner root-canal walls at the middle and apical thirds, 0.5% NaOCl used with the same technique achieved no root-canal cleaning. However, pretreatment of root canals with Ca(OH)2 paste increased the effectiveness of 0.5% NaOCl plus ultrasonic irrigation, except in the coronal third of the root canal.

Canal debridement: effectiveness of sodium hypochlorite and calcium hydroxide as medicaments

The action of chemicals such as calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCl) that are used as tissue solvents may be enhanced by prolonged contact. The objective of this study was to determine if sealing Ca(OH)2 and NaOCl into the canal space would improve debridement of both the main canal and areas inaccessible to files. Mesial root canals of 75 freshly extracted mandibular molars were step-back hand-instrumented. Another six molars were controls. Either Ca(OH)2, NaOCl, or no medication was sealed in the canals for 1 or 7 days. Canals were finally irrigated with H2O and prepared for histological evaluation. The cleanliness of main canals and inaccessible areas (isthmi and fins) at the apical, middle, and coronal thirds was examined, scored, and compared by nonparametric statistical analysis. Results showed no significant differences among different groups in either the 1-day or 7-day time intervals in either the main canal or inaccessible areas. Instrumentation combined with NaOCl irrigation alone accounted for the removal of tissue in the main canal. In conclusion, in this system, prolonged contact with Ca(OH)2 and NaOCl was similarly ineffective; neither contributed significantly to canal debridement.

In vitro efficiency of endodontic irrigation solutions on protein desorption

The use of irrigating solutions is widely accepted as a necessary adjunct to biomechanical preparation to obtain adequate cleansing of the root canal system. In this study, the efficiency of three solutions was tested in an in vitro experimental system for the removal of protein from apatite surfaces: Salvizol (a bis-dequalinium acetate solution) and sodium hypochlorite at 0.5, 1, 3 and 6% at pH 7.4 and 11.5. Buffered Tris-HCl solutions at pH 7.4 and 11.5 were used as controls. All chemicals showed rapid kinetics effects since no variation of the process could be detected after 5 min. Salvizol was the least efficient solution since it induced only a 2% protein desorption. Sodium hypochlorite efficiency increased with concentration to reach a 70% protein desorption from the apatite surface. In general, alkaline solutions were more efficient than buffered ones, and the ionic strength did not appear to have a major effect on the protein desorption process.

Antibacterial effects of various endodontic irrigants on selected anaerobic bacteria

This study was undertaken to determine the antibacterial effects of various endodontic irrigants against six selected anaerobic bacteria. The organisms were mixed separately with dilutions of each of the irrigants in tubes containing fluid thioglycollate broth and allowed to remain in contact for specific time periods before being evaluated for growth. Of the six irrigants tested, chlorhexidine appeared to be the most effective antibacterial substance. Hydrogen peroxide, sodium hypochlorite and REDTA were less effective while the calcium hydroxide and saline solutions proved to be totally ineffective.

The role of intracanal medication in root canal treatment

The role of intracanal medication as a root canal dressing is re-examined. In pulpectomy and some root canal treatments, where the root canal contains vital pulp tissue, it is doubtful whether a routine intracanal medicament is needed. In infected root canals, intracanal medication has been advocated for many purposes. An intracanal medicament is used to: (i) eliminate any remaining bacteria after canal instrumentation; (ii) reduce inflammation of periapical tissues and pulp remnants; (iii) render canal contents inert and neutralize tissue debris; (iv) act as a barrier against leakage from the temporary filling; (v) help to dry persistently wet canals. However, most of the indications for intracanal medicaments are questionable. Intracanal medicaments should only be used for root canal disinfection as part of controlled asepsis in infected root canals, and their role is secondary to cleaning and shaping of the root canal. Thorough canal debridement and adequate canal preparation are more pertinent, and their importance is emphasized. Bacteriological sampling may be necessary if a tooth does not respond to treatment, to help in the choice of intracanal medicament.