Agonistic and Antagonistic Interactions between Chlorhexidine and Other Endodontic Agents: A Critical Review

Root canal irrigants play a significant role in elimination of the microorganisms, tissue remnants, and removal of the debris and smear layer. No single solution is able to fulfill all these actions completely; therefore, a combination of irrigants may be required. The aim of this investigation was to review the agonistic and antagonistic interactions between chlorhexidine (CHX) and other irrigants and medicaments. An English-limited Medline search was performed for articles published from 2002 to 2014. The searched keywords included “chlorhexidine AND sodium hypochlorite/ethylenediaminetetraacetic acid/calcium hydroxide/mineral trioxide aggregate". Subsequently, a hand search was carried out on the references of result articles to find more matching papers. Findings showed that the combination of CHX and sodium hypochlorite (NaOCl) causes color changes and the formation of a neutral and insoluble precipitate; CHX forms a salt with ethylenediaminetetraacetic acid. In addition, it has been demonstrated that the alkalinity of calcium hydroxide (CH) remained unchanged after mixing with CHX. Furthermore, mixing CHX with CH may enhance its antimicrobial activity; mixing mineral trioxide aggregate (MTA) powder with CHX increases its antimicrobial activity but may have a negative effect on its mechanical properties

Recent Advances in Root Canal Disinfection: A Review

The microbial biofilm is an important factor for human infection. Finding effective antimicrobial strategies should be considered for decreasing antimicrobial resistance and controlling the infectious diseases. Treatment of infected canal systems may not be able to remove all bacteria and so bacterial persistence after treatment may occur. Application of antibacterial nanoparticles may be a potential strategy to improve the elimination of bacteria from the canal. Furthermore, mechanism of action and applications of photodynamic therapy and Photon-induced photoacoustic streaming (PIPS) and GentleWave system was reviewed.Keywords: GentleWave Irrigation; Nano-Particles; Nano-Technology; Photodynamic Therapy; Photon-Induced Photo Acoustic Streaming; Root Canal Disinfection

Microbial Biofilms in Endodontic Infections: An Update Review

Biofilms and microbial aggregates are the common mechanisms for the survival of bacteria in nature. In other words, the ability to form biofilms has been regarded as a virulence factor. Microbial biofilms play an essential role in several infectious diseases such as pulp and periradicular pathosis. The aim of this article was to review the adaptation mechanisms of biofilms, their roles in pulpal and periapical pathosis, factors influencing biofilm formation, mechanisms of their antimicrobial resistance, models developed to create biofilms, observation techniques of endodontic biofilms, and the effects of root canal irrigants and medicaments as well as lasers on endodontic biofilms. The search was performed from 1982 to December 2010, and was limited to papers in English language. The keywords searched on Medline were "biofilms and endodontics," "biofilms and root canal irrigation," "biofilms and intra-canal medicament," and "biofilms and lasers." The reference section of each article was manually searched to find other suitable sources of information

Root Canal Irrigants and Dentin Bonding: An Update

The purpose of the review was to assess the effect of root canal irrigants on dentin bonding. A PubMed-based search was conducted on the articles published from 1980 to 2016. A brief overview and reviewing the effect on dentin bonding of common root canal irrigation solutions such as sodium hypochlorite (NaOCl), chlorhexidine (CHX), ethylenediaminetetraacetic acid (EDTA), mixture of a tetracycline, acid and a detergent (MTAD) and ozone was conducted. Findings showed that, depending on the type of dentin bonding, using NaOCl may decrease, increase or not affect the bond strength. In addition, due to its broad-spectrum matrix metalloproteinase-inhibitoryeffect, CHX as well as MTAD can significantly improve the resin-dentin bondstability. However, the effect of ozone therapy on bond strength was controversial.Keywords: Bond Strength; Chlorhexidine; EDTA; MTAD; Ozone; Sodium Hypochlorit

Impact of Ultrasonic Activation on the Effectiveness of Sodium Hypochlorite: A Review

Using ultrasonic devices in endodontics can enhance the antibacterial and tissue dissolving ability of different root canal irrigants such as sodium hypochlorite (NaOCl) which is the most common irrigant with excellent antibacterial and tissue dissolving abilities. However, due to its high surface tension, its penetration into the irregularities of the root canal system is a challenge. The purpose of this paper was to review the different ultrasonic devices, different types of ultrasonic irrigation, the effect(s) of ultrasonic activation on the antibacterial and biofilm-removal abilities of NaOCl as well as the effect of ultrasonic activation on the smear layer removal ability of NaOCl.Keywords: Antibacterial Activity; Biofilm; Root Canal Irrigants; Smear Layer; Sodium Hypochlorite; Ultrasonic Activatio

Debridement effectiveness of two different techniques using negative pressure irrigation system

Summary Objectives To evaluate the cleaning efficacy of two apical negative pressure irrigation techniques compared to needle irrigation. Materials and Methods Eighty extracted human single canal teeth were shaped and assigned to 3 experimental groups (n = 20) according to the irrigation technique performed and two negative control groups (n = 10) as follows: 1) NI (Max-I-Probe side-vented needle irrigation); 2) EV (EndoVac system); 3) EVM (EndoVac-modified technique); 4) EV-C (EndoVac-negative control); 5) NI-C (needle irrigation-negative control). A scanning electron microscopic evaluation was performed. The presence of debris and smear layer at all levels (coronal, middle, apical) was evaluated. Results and conclusions A new irrigation protocol, using EndoVac System resulted in better removal of the smear layer at all levels

Penetration of Sodium Hypochlorite Modified with Surfactants into Root Canal Dentin

Abstract The aim of this study was to evaluate the effect of concentration, exposure time and temperature of sodium hypochlorite (NaOCl) added with surfactants on its penetration into dentinal tubules. Sixty-five extracted human permanent maxillary anterior teeth with single canals were prepared by ProTaper SX hand-operated instruments. The teeth were then sectioned perpendicular to the 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 and thirty stained blocks were further split into halves and treated by nine different types of NaOCl-based solutions. Three solutions were added with surfactants (Hypoclean, H6, Chlor-Xtra) and the others were regular hypochlorites at increasing concentrations (1%, 2%, 4%, 5.25%, <6%, 6% NaOCl) from different brands. The dentin blocks were exposed to the solutions for 2, 5, and 20 min at 20 °C, 37 °C and 45 °C, respectively. The depth of NaOCl penetration was determined by bleaching of the stain and measured by light microscopy at 20 and 40. Statistical comparisons were made by using a generalized linear model with Bonferroni's post-hoc correction. The shortest penetration (81±6.6 μm) was obtained after incubation in 1% NaOCl for 2 min at 20 °C; the highest penetration (376.3±3.8 μm) was obtained with Chlor-Xtra for 20 min at 45 °C. Varying NaOCl concentration produced a minimal effect while temperature and exposure time had a significant direct relationship with NaOCl penetration into dentinal tubules, especially those with lowered surface tension. 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

Comparative wettability of different sodium hypochlorite solutions

Summary Objectives The present study evaluated the dentin wettability of sodium hypochlorite (NaOCl) with and without the addition of surfactants. Materials and methods Twelve premolars roots were longitudinally split using a low-speed rotary diamond saw. The 24 specimens were randomly distributed into four experimental groups: Group 1 = 5.25% NaOCl; Group 2 = Hypoclean; Group 3 = Chlor-Xtra; Group 4 = freshly produced MilliQ water (distilled water). Three different contact angles were measured: the sessile angle, the advancing angle, and the receding angle. All angles were measured with a goniometer Kruss G 23. Results The highest contact angle was observed in Group 4 (control group), considering both sessile and advancing angles. Hypoclean and Chlor-Xtra solutions immediately spread on the dentin surface, yielding a zero-degree contact angle. Pure NaOCl solution showed a 35-degree sessile contact angle and a 64-degree advancing contact angle. The detected receding angle was zero. Conclusions Obtained data clearly showed the superior wettability of Hypoclean and Chlor-Xtra in comparison to pure NaOCl and distilled water

Comparison of Antimicrobial Substantivity of Six Root Canal Irrigants against Enterococcus faecalis

Introduction: The antimicrobial substantivity of Mixture of Doxycycline, Citric acid, and Tween 80 (MTAD), Tetraclean, Tetraclean NA, Q-Mix, 2% Chlorhexidine (CHX) and Octenisept was assessed in human root dentine blocks infected with Enterococcus (E.) faecalis. Methods and Materials: A total of 170 dentine tubes were prepared from human maxillary incisors. After crown and apical third removal, cementum was abraded. The remaining center-holed pieces were cut into 4-mm blocks, infected with E. faecalis in Brain Heart Infusion (BHI) broth for 28 days, then randomly divided into 6 experimental groups (n=25) and 2 controls (n=10). At 0, 7, 14, 21 and 28 days, dentine chips were removed from the canals, with sequential round burs with increasing diameters, and collected into freshly prepared BHI broth. After culturing, growing colonies were counted as colony forming units (CFU). Conventional non-parametric tests (Kruskal-Wallis and Mann-Whitney tests) were used to assess intra-group (at different time frames) and inter-group (at each experimental time) differences (P=0.05). Results: Tetraclean yielded the lowest CFU counts (P&lt;0.001) at each observation time. Tetraclean NA and Q-Mix showed better (P&lt;0.001) substantivity than 2% CHX and MTAD (except for Q-Mix versus MTAD at 14 days, P=0.21). Conclusions: In this in vitro study, Tetraclean NA and Q-Mix displayed the best antimicrobial substantivity against E. faecalis after Tetraclean in infected human root dentine. Considering the findings of our study and potential drawbacks of antibiotic-based irrigants, free-antibiotic irrigants may represent viable alternative for final rinse in root canal treatment.Keywords: Antimicrobial Substantivity; Enterococcus faecalis; MTAD; Qmix; Tetraclea

Management of Root Resorption Using Chemical Agents: A Review

Root resorption (RR) is defined as the loss of dental hard tissues because of clastic activity inside or outside of tooth the root. In the permanent dentition, RR is a pathologic event; if untreated, it might result in the premature loss of the affected tooth. Several hypotheses have been suggested as the mechanisms of root resorption such as absence of the remnants of Hertwig's epithelial root sheath (HERS) and the absence of some intrinsic factors in cementum and predentin such as amelogenin or osteoprotegerin (OPG). It seems that a barrier is formed by the less-calcified intermediate cementum or the cementodentin junction that prevents external RR. There are several chemical strategies to manage root resorption. The purpose of this paper was to review several chemical agents to manage RR such as tetracycline, sodium hypochlorite, acids (citric acid, phosphoric acid, ascorbic acid and hydrochloric acid), acetazolamide, calcitonin, alendronate, fluoride, Ledermix and Emdogain.Keywords: Alendronate; Calcitonin; Citric Acid; Emdogain; Fluoride; Osteoclast; Root Resorption; Tetracyclin