Risk assessment of the toxicity of solvents of gutta-percha used in endodontic retreatment

Endodontic retreatment efficacy with and without solvents: A systematic review

Introduction

This systematic review investigates the crucial need for solvent use in root canal retreatment, as it effectively removes filling materials, reduces apical debris extrusion, and alleviates postoperative pain, ultimately enhancing treatment success. The review aims to assess the success rates, compare outcomes, explore benefits and drawbacks, and identify subgroups where solvent use may be more effective during root canal retreatment.

Materials and Methods

The search was performed in PubMed Central, Scopus, Cochrane, LILAC, ScienceDirect, Google Search, Web of Science, and manually using the search items alone and in combination by means of PUBMED search builder. The studies were assessed for eligibility according to the eligibility criteria by two independent reviewers. Groups containing solvent with nonsolvent groups and randomized control trials were included and in vitro studies, retrospective studies, and animal studies were excluded from the study. Quality assessment was performed using the risk of bias (RoB) 2.0 tool.

Results

Out of the 596 articles obtained, 14 were shortlisted for full-text reading and finally two articles were included in the study. The studies were assessed for quality, and data were extracted in a tabulated form. Overall RoB is low, but due to the lack of homogeneity, meta-analysis could not be conducted.

Conclusion

The use of solvent does not cause any significant difference in the postoperative pain levels or analgesic intake for retrieval of gutta-percha in cases of root canal retreatment. Due to the limited number of studies available and the lack of clinician-related outcomes such as time taken to retrieve the gutta-percha, these results should be taken into consideration with caution.

An in vitro evaluation of effectiveness of Xylene, Thyme oil and Orange oil in dissolving three different endodontic sealers

Aims

The aim of the study is to compare the dissolution effectiveness of xylene, thyme oil, and orange oil on three different endodontic sealers.

Materials and Methods

Standardized stainless steel molds were used to prepare 210 samples (70 for each endodontic sealer). The samples were divided into three groups based on sealers. Three experimental groups with 20 samples each were immersed in organic solvents. One control group of 10 samples was immersed in distilled water. Each group was further subdivided into two subgroups based on immersion time (2 and 10 min). Inferential statistics included one-way ANOVA, post hoc Tukey, and paired t-test.

Results

Thyme showed significantly more dissolution capacity at 10 min compared to 2 min in dissolving AH Plus sealer whereas this difference was nonsignificant for Roekoseal and MTA Fillapex. Orange oil showed significantly more dissolution at 10 min compared to 2 min in dissolving AH Plus sealer and Roekoseal whereas this difference was nonsignificant concerning MTA Fillapex. Xylene showed significantly more dissolution capacity at 10 min compared to 2 min in dissolving AH Plus sealer, Roekoseal, and MTA Fillapex.

Conclusions

Among the three solvents, xylene showed the highest dissolution of all three sealers. Orange oil was superior to thyme oil in dissolving the sealers. All the sealers showed more dissolution in all the solvents at 10 min compared to 2 min.

Efficiency of the new reciprocating and rotary systems with or without ultrasonics in removing root-canals filling with calcium silicate-based sealer (MTA)

BACKGROUND

To compare the efficiency of endodontic rotary and reciprocating systems in removing calcium silicate-sealer based fillings and to investigate the impact of passive ultrasonic irrigation (PUI) on their efficiency.

MATERIALS AND METHODS

160 root-canals were instrumented, filled with gutta-percha and calcium silicate based-sealer and divided into 10 equal groups. Five groups in which the reciprocating systems (WaveOne-Gold, Reciproc-Blue and R-Motion) and rotary systems (Fanta-AF-One and Tango-Endo) were used to remove root-canals' fillings. In the other five groups the fillings were removed by the same systems then additionally with PUI. The times to complete retreatments procedures were recorded. Micro-computed tomography's analysis of the root-canals fillings' volume before and after retreatments was used to determine the remaining filling materials (RFMs) volumes.

RESULTS

The RFMs after using rotary systems (10.1%) was greater than after using reciprocating systems (3.8%) (P < 0.001). The RFMs after using WOG (2%) and RB systems (2.6%) were less than those in the RM (6.8%), TE (9.5%) and FAFO (10.7%) systems [P < 0.05]. The times required to remove the filling materials using the TE (3.7 min), FAFO (4.1 min) and RM (4.1 min) systems were shorter than those required by the RB (5.4 min) and WOG (4.9 min) systems [P < 0.05]. Using PUI resulted in less RFMs (1.44%) when compared to using only rotary or reciprocating systems (6.27%) [P < 0.001].

CONCLUSIONS

Endodontic reciprocation systems were more effective, but needed longer times than rotary systems in removing calcium silicate based- sealers fillings. The PUI significantly improved removal of the root-canals' filling materials.

CLINICAL RELEVANCE

Reciprocating systems and PUI are recommended whenever root-canals retreatment is considered regardless of using calcium silicate-based sealers.

Efficiency of reciprocating systems reciprocated at different angles in removing root-canals fillings with an MTA-type sealer: an Ex-vivo study

BACKGROUND

There have been no reports on the impact of different reciprocating angles on retreatment performance of reciprocating files. This ex-vivo study compared the efficiency of three reciprocating systems in removing MTA-type sealer-based filling materials and investigated the influence of different reciprocating angles on their retreatment ability.

METHODS

140 root-canals were instrumented to a 35 apical size and filled with an MTA-type sealer and gutta-percha cones. Samples were scanned by micro-computed-tomography and the root-canals fillings volumes were measured. Samples were divided into 7 groups according to the reciprocating angles at which the WaveOne-Gold (WOG), Reciproc-Blue (RB) and R-Motion (RM) systems were reciprocated to remove the root-canals' fillings. The WOG-150/30, WOG-90/30, RB-150/30, RB-90/30, RM-150/30 and RM-90/30 groups in which the systems were reciprocated at 150/30 and 90/30 (counterclockwise/clockwise) angles. In the RB-270/30 group the RB system was reciprocated at 270/30 angles. Samples were re-scanned and the remaining filling materials' (RFMs) volumes were measured. The percentage of the RFMs volume and its mean value for each group were calculated and data were statistically analysed at 0.05 significance level.

RESULTS

The WOG system resulted in less RFMs (2.24%) when reciprocated at 90/30 angles compared to that resulted from the 150/30 angles (4.96%) [P = 0.002]. The RB system reciprocated at 90/30 angles resulted in less RFMs (2.67%) compared to that resulted from the 270/30 angles (6.64%) [P = 0.001]. The RFMs after using RM system reciprocated at 90/30 (6.02%) and 150/30 (7.61%) were greater than those of WOG (2.24 and 4.96%) and RB (2.67 and 4.34%) reciprocated at the same angles (P < 0.05). The longest time required to remove the filling materials was recorded with the RB-270/30 group (6.06 min) [P = 0.00]. The times required when the WOG, RB and RM files reciprocated at 90/30 angles (3.59, 3 and 3.05 mins, respectively) were shorter than those when files were reciprocated at 150/30 angles (5.25, 4.98 and 3.67 min, respectively) [P < 0.05].

CONCLUSIONS

The WOG and RB systems removed more MTA-type sealer-based root-canals fillings than the RM system. Lower counterclockwise reciprocating angles improve the retreatment ability of reciprocating systems, especially the WOG system and can reduce the time required for retreatment procedures.

The Novel Role of Solvents in Non-Surgical Endodontic Retreatment

Non-surgical endodontic retreatment is a reliable conservative option for managing post-treatment apical periodontitis. However, effective microbial control, based on the maximization of filling removal and disinfection protocols, is not yet predictable. Traditional gutta-percha solvents, which are indistinctively used for both the core and sealer filling materials, became obsolete due to unprecedented advances in endodontic technology. Nonetheless, microtomography, scanning electronic microscopy findings, and histobacteriological analysis tend to confirm the persistence of filling materials and the lack of association between root canal enlargement and superior disinfection. There is a controversy regarding the most suitable clinical protocols surrounding the shaping procedures and the supplementary disinfection steps. Based on the literature and the previous work of the team, the authors aimed to summarize the current knowledge regarding specific solvent formulations that target filling materials. Additionally, the advantage of an additional irrigation step to optimize disinfection was highlighted. This adjunctive procedure serves a dual role in the dissolution of filling materials, and in conferring an antibiofilm effect. Further research is needed to understand the novel contribution of these strategies upon clinical practice outcomes.

Evaluation of Antibacterial Properties of Organic Gutta-percha Solvents and Synthetic Solvents Against Enterococcus faecalis

Background:

The use of solvents is necessary to remove remnants of filling materials within dentinal tubules to allow penetration of irrigating solution within the tubules.

Aim and Objectives:

We aimed at determining the antibacterial effect of various gutta-percha (GP) solvents against Enterococcus faecalis (E. faecalis).

Materials and Methods:

An in vitro study was conducted by measuring the zone of inhibition using the disk diffusion method. The test organism used for the study was E. faecalis, and the solvents were divided into five groups: eucalyptus oil, chloroform, turpentine oil, xylene, and orange oil. About 500 μL of the suspension was spread over the agar plates, and the empty sterilized disks were impregnated with 10 μL of pure essential oils (EOs). The inoculated plates were incubated at 37°C for 18 to 24 h. The antimicrobial activity of each solvent was expressed and measured in terms of the mean diameter of the zone of inhibition (in mm) produced by each solvent at the end of the incubation period. ANOVA was used for intergroup comparison. The P-value of <0.05 was considered significant.

Results:

The mean zone of inhibition for E. faecalis was 24.00 ± 1.21 for eucalyptus oil, 16.30 ± 0.92 for chloroform, 26.50 ± 1.24 for turpentine oil, 13.70 ± 1.26 for xylene, and 19.80 ± 1.32 for orange oil. The difference between the groups was statistically significant (P < 0.001).

Conclusion:

This study demonstrated that the use of turpentine oil during endodontic retreatment significantly reduced the levels of E. faecalis as compared with other solvents.

Natural Polymer Eucommia Ulmoides Rubber: A Novel Material

As the second natural rubber resource, Eucommia ulmoides rubber (EUR) from Eucommia ulmoides Oliver is mainly composed of trans-1,4-polyisoprene, which is the isomer of natural rubber cis-1,4-polyisoprene from Hevea brasiliensis. In the past few years, the great potential application of EUR has received increasing attention, and there is a growing awareness that the natural polymer EUR could become an emerging research topic in field of the novel materials due to its unique and excellent duality of both rubber and plastic. To gain insight into its further development, in this review, the extraction, structure, physicochemical properties, and modification of EUR are discussed in detail. More emphasis on the potential applications in the fields of the environment, agriculture, engineering, and biomedical engineering is summarized. Finally, some insights into the challenges and perspectives of EUR are also suggested.

Economic Analysis of a New Business for Liposome Manufacturing Using a High-Pressure System

Supercritical assisted Liposome formation (SuperLip) is a lab-scale process for the production of liposomes. SuperLip was recognized as being a versatile supercritical assisted technique for the encapsulation of molecules for different industrial applications, such as pharmaceutic, cosmetic, textile, and nutraceutic purposes. The aim of this work was to perform an economic analysis to assess the profitability of the SuperLip process. The liposomes market was analyzed and the SuperLip process was compared to other techniques in terms of manufacturing advantages using the Canvas and Strengths, Weaknesses, Opportunities, and Treats (S.W.O.T.) models. SuperLip Plant Capital Expenditures (CAPEX) were estimated, and plant Operating Expenditures (OPEX) were also evaluated and integrated with personnel cost and other plant goods and services. A profit and loss statement was generated, together with a cash flow analysis. According to the market average selling price, liposome price is 1.8 €/mL; in order to join the market rapidly, the selling price of liposomes produced using SuperLip was set at 1.1 €/mL. A payback time has been identified at the fourth year of business. Economic indexes such as ROI and ROS were calculated on a 10-year business prospect, obtaining about a 230% return on investment and a 26.7% return on sales.

Retreatment efficacy of hydraulic calcium silicate sealers used in single cone obturation

OBJECTIVE

Removal of obturating materials from the root canal during retreatment is usually accomplished by mechanical means and organic solvents to dissolve the gutta-percha. This strategy is ineffective on sealers. The aim of this research was to assess the efficacy of mechanical instrumentation aided by targeted chemical means for removal of hydraulic sealers.

METHODS

A preliminary study assessed the effect of 17% EDTA and 10/20% formic acid applied for 5 or 10 min on dentine and for 5 min on Totalfill BC sealer (FKG). Microhardness and structural integrity by scanning electron microscopy and energy dispersive spectroscopy were investigated. The optimal solutions were used as adjuncts to mechanical instrumentation to remove obturations made with single cone using a standard gutta-percha and bioceramic coated gutta-percha and Totalfill BC sealer. The removal of obturation material from the root canal system of obturated teeth was evaluated using microcomputed tomography. The canal patency and reestablishment of working length were also checked.

RESULTS

The preliminary study showed that 17% EDTA and 10% formic acid applied for 5 min did not damage the dentine but effected the structural integrity of the sealer. 10% formic acid used in conjunction with mechanical instrumentation was the most efficient method to remove the obturation material from the root canal, achieving over 95% removal for both gutta-percha and the bioceramic coated version and also achieve patency and reestablishment of working length.

CONCLUSIONS

The use of a targeted irrigation protocol with a chemical adjunct to the mechanical instrumentation is the best way to retreat teeth obturated with hydraulic calcium silicate sealer and gutta-percha.

A Comparative Evaluation of Two Commonly Used GP Solvents on Different Epoxy Resin-based Sealers: An In Vitro Study

AIM

This study evaluates epoxy resin-based sealers after their final set, immersed in Endosolve-R or xylene for 1-2 minutes, for its easy removal mechanically after softening.

MATERIALS AND METHODS

Sixty Teflon molds were grouped with 20 samples in each of the three commercially available sealers, i.e., AH 26, AH Plus, and Adseal. The sealers were put in the specific molds after their manipulation as per the instructions given in the literature by the manufacturer. They were allowed to harden for 2 weeks at 37°C in 100% humidity. Two subgroups, A-Xylene and B-Endosolv-R, of 10 samples each, were formed from 20 set specimens based on solvents to which they were immersed for 1 and 2 minutes, respectively. The data obtained was subjected to the Mauchly's test one-way ANOVA and two-way ANOVA for analysis.

RESULTS

It was proved that for all the sealers immersed in solvents, there was a significant reduction in the mean Vickers hardness as the time increases. There was a significant difference in the initial hardness between the mentioned sealers with AH plus showing the highest followed by AH 26 and Adseal showing the lowest. AH Plus and Adseal sealers were softened by xylene after 2 minutes of their initial microhardness (p < 0.001); least effect was seen on AH 26. After 2 minutes, Endosolv-R softened initial microhardness of all the three sealers (p < 0.001).

CONCLUSION

It was concluded that Endosolv-R was more effective in softening the epoxy-based resin sealer than xylene, after 2 minutes of exposure.

HOW TO CITE THIS ARTICLE

Tyagi S, Choudhary E, Choudhary A, et al. A Comparative Evaluation of Two Commonly Used GP Solvents on Different Epoxy Resin-based Sealers: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(1):35-37.

Quantification by SIFT-MS of volatile compounds produced by the action of sodium hypochlorite on a model system of infected root canal content

Root canal irrigation with sodium hypochlorite (NaOCl) is an indispensable part of the chemomechanical preparation of infected root canals in Endodontology. However, there is limited information on the emergence of toxic or hazardous volatile compounds (VOCs) from the interaction of NaOCl with the infected content of tooth biomaterials. The aim of this study was to assess the formation of VOCs and disinfection by-products (DBPs) following the interaction of NaOCl 2.5% v/v with a model system of different sources of natural organic matter (NOM) present in infected root canals, including dentine powder, planktonic multi-microbial suspensions (Propionibacterium acnes, Staphylococcus epidermidis, Actinomyces radicidentis, Streptococcus mitis and Enterococcus faecalis strain OMGS3202), bovine serum albumin 4%w/v and their combination. NaOCl was obtained from a stock solution with iodometric titration. Ultrapure water served as negative control. Samples were stirred at 37°C in aerobic and anaerobic conditions for 30min to approximate a clinically realistic time. Centrifugation was performed and the supernatants were collected and stored at -80⁰ C until analysis. The reaction products were analysed in real time by selected ion flow tube mass spectrometry (SIFT-MS) in triplicates. SIFT-MS analysis showed that the released VOCs included chlorinated hydrocarbons, particularly chloroform, together with unexpected higher levels of some nitrogenous compounds, especially acetonitrile. No difference was observed between aerobic and anaerobic conditions. The chemical interaction of NaOCl with NOM resulted in the formation of toxic chlorinated VOCs and DBPs. SIFT-MS analysis proved to be an effective analytical method. The risks from the rise of toxic compounds require further consideration in dentistry.

The efficacy of retreatment and new reciprocating systems in removing a gutta-percha-based filling material

Objectives

To investigate the efficacy of retreatment and reciprocating rotary systems in removing gutta-percha filling material from root-canal systems.

Methods

A total of 90 single-canal human teeth were instrumented using a F3 ProTaper file and obturated with gutta-percha and the Tubliseal sealer using the lateral-compaction technique. They were divided into five groups according to the rotary system used to remove the filling material: Reciproc, which used the Reciproc-R25 file; WaveOne, which used the WaveOne-Primary file; S1, which used the S1 (25/.06) file; ProTaper-R, which used the ProTaper-Retreatment system; and Mtwo-R, which used the Mtwo®-Retreatment system. The time required to remove the filling material (min) and the associated instrument separation, if any, were recorded. Teeth were cleaved longitudinally and photographed with a high-resolution camera. Images were imported to the AutoCAD application to measure the remaining filling material and the root-canal space. Data were analysed using the one-way analysis of variance and Chi-squared tests.

Results

The Mtwo-R group showed the highest mean remaining filling material (51%) (p < 0.001), with no significant differences among the other groups. The ProTaper group required the least time for filling-material removal (4.95 min), with significant differences compared to the other groups (p < 0.05), except the WaveOne group (5.83 min; p = 1.000). Overall, 13 instruments (15.9%) were used for filling-material removal, with a significantly greater proportion in the Mtwo-R group (33.3%) compared to the other groups (p = 0.009).

Conclusions

Within the limitations of this in vitro study, reciprocating rotary systems were as effective as retreatment rotary systems in removing root-canal filling material. The Mtwo-R system showed the poorest performance with respect to removal effectiveness and instrument separation.

Hazards of Improper Dispensary: Literature Review and Report of an Accidental Chloroform Injection

Several clear, transparent solutions are used in endodontics. Inappropriate dispensing methods can lead to accidental injection or accidental irrigation. These accidents can cause permanent tissue damage including damage to the bone, periodontium, nerves, and vasculature. This article reports on the consequences of an accidental chloroform injection. Nonsurgical retreatment of tooth #8 was planned as part of a restorative treatment plan in a 69-year-old woman. The dentist accidentally injected chloroform instead of local anesthesia because chloroform was loaded into the anesthetic syringe. The patient experienced severe pain and swelling and soft tissue necrosis and suffered permanent sensory and motor nerve damage. A review of the literature was performed on accidents caused by improper dispensary, namely accidental injections and accidental irrigations. The data were extracted and summarized. Sodium hypochlorite, chlorhexidine, formalin, formocresol, 1:1000 adrenaline, benzalkonium chloride, and lighter fuel were accidentally injected as an intraoral nerve block or as infiltration injections. Bone and soft tissue necrosis, tooth loss, and sensory nerve damage (anesthesia and paresthesia) were the most common consequences reported. Such disastrous events can be prevented by appropriate labeling and separate dispensing methods for each solution. There is a need for disseminating information on toxicity and biocompatibility of materials/solutions used in endodontics. The authors recommend training dental students and endodontic residents on immediate and long-term therapeutic management of patients when an accidental injection or accidental irrigation occurs.

Endodontic Management of Open Apex Teeth Using Lyophilized Collagen Sponge and MTA Cement: Report of Two Cases

Teeth with open apices, such as in immature teeth or those with apical root resorption are clinical cases with difficult immediate resolution. With the use of mineral trioxide aggregate (MTA) in dentistry, it was possible to optimize the treatment time of these cases by immediate placement of apical plug and the root canal filling. However, some negative effects can occur if MTA is extruded beyond the apex. To avoid this accident, it has been recommended to use of an apical matrix prior to placement of MTA. This study reports two clinical cases of apical plug placement in teeth with pulp necrosis and open apices. One case had an immature apex due to dental trauma and the other case had apical resorption due to the presence of endodontic infection in the root canal. MTA apical plug with approximately 4 mm thickness, was placed in the apical zone of the root and immediately the canal was obturated with gutta-percha and endodontic sealer. Follow-up evaluations showed clinical and radiographic evidence of success.

Efficacy of Different Irrigation Protocols for Removing Gutta-Percha and Sealer Remnants in Artificial Un-instrumented Areas

Objective:

The purpose of this study was to determine the efficacy of different irrigants and irrigation protocols in the removal of gutta-percha and sealer from simulated un-instrumented areas.

Methods:

Eighty-four uniradicular teeth were used. After standardizing working length (WL) and preparing the glide path, coronal flaring was performed. The instrumentation phase was completed with ProFile rotary instruments up to size #35 LightSpeed LSX. Roots were split into halves: in one of them, a groove was prepared in the apical 6 mm. In the opposite one, 5 depressions were made (at 2, 4, 6, 8 and 10 mm). Irregularities were filled with AH Plus sealer and flowable gutta-percha. The Efficacy of sodium hypochlorite (NaOCl) and chloroform in removal of material and the effect of positive pressure (PP), passive ultrasonic irrigation (PUI) (one or three cycles) and paper points were analysed with the chi-square test.

Results:

Delivery by PP did not eliminate the obturator material from any artificial depression. Chloroform, when activated, demonstrated a significant linear trend in the amount of gutta-percha removed at all tested levels (P<0.01). The use of paper points after passive delivery of chloroform increased significantly the removal of gutta-percha in the groove and at 4 and 10 mm (P<0.05). Three cycles of PUI and chloroform showed significantly fewer remnants of gutta-percha (P<0.01).

Conclusion:

Positive pressure was not effective in the removal of obturator materials with any of the tested irrigants. Chloroform delivered by PP in combination with paper points obtained a better cleaning efficacy, although its activation using PUI for three cycles of 20 s showed the best cleanliness.

Retreatability of two endodontic sealers, EndoSequence BC Sealer and AH Plus: a micro-computed tomographic comparison

OBJECTIVES

Recently, bioceramic sealers like EndoSequence BC Sealer (BC Sealer) have been introduced and are being used in endodontic practice. However, this sealer has limited research related to its retreatability. Hence, the aim of this study was to evaluate the retreatability of two sealers, BC Sealer as compared with AH Plus using micro-computed tomographic (micro-CT) analysis.

MATERIALS AND METHODS

Fifty-six extracted human maxillary incisors were instrumented and randomly divided into 4 groups of 14 teeth: 1A, gutta-percha, AH Plus retreated with chloroform; 1B, gutta-percha, AH Plus retreated without chloroform; 2A, gutta-percha, EndoSequence BC Sealer retreated with chloroform; 2B, gutta-percha, EndoSequence BC Sealer retreated without chloroform. Micro-CT scans were taken before and after obturation and retreatment and analyzed for the volume of residual material. The specimens were longitudinally sectioned and digitized images were taken with the dental operating microscope. Data was analyzed using an ANOVA and a post-hoc Tukey test. Fisher exact tests were performed to analyze the ability to regain patency.

RESULTS

There was significantly less residual root canal filling material in the AH Plus groups retreated with chloroform as compared to the others. The BC Sealer samples retreated with chloroform had better results than those retreated without chloroform. Furthermore, patency could be re-established in only 14% of teeth in the BC Sealer without chloroform group.

CONCLUSION

The results of this study demonstrate that the BC Sealer group had significantly more residual filling material than the AH Plus group regardless of whether or not both sealers were retreated with chloroform.

Evaluation of softening ability of Xylene & Endosolv-R on three different epoxy resin based sealers within 1 to 2 minutes - an in vitro study

OBJECTIVES

This study evaluated the efficacy of Endosolv-R and Xylene in softening epoxy resin based sealer after 1 to 2 min exposure.

MATERIALS AND METHODS

Sixty Teflon molds (6 mm × 1.5 mm in inner diameter and depth) were equally divided into 3 groups of 20 each. AH 26 (Dentsply/De Trey), AH Plus (Dentsply/De Trey), Adseal (Meta-Biomed) were manipulated and placed in the molds allotted to each group and allowed to set at 37℃ in 100% humidity for 2 wk. Each group was further divided into 2 subgroups according to the solvents used, i.e. Xylene (Lobachemie) and Endosolv-R (Septodont). Specimens in each subgroup were exposed to respective solvents for 1 and 2 min and the corresponding Vicker's microhardness (HV) was assessed. Data was analysed by Mauchly's test and two-way analysis of variance (ANOVA) with repeated measures, and one-way ANOVA.

RESULTS

Initial hardness was significantly different among the three sealers with AH Plus having the greatest and Adseal having the least. After 2 min, Xylene softened AH Plus and Adseal sealer to 11% and 25% of their initial microhardness, respectively (p < 0.001), whereas AH 26 was least affected, maintaining 89.4% of its initial microhardness. After 2 min, Endosolv-R softened AH 26, AH Plus and Adseal to 12.7, 5.6 and 8.1% of their initial microhardness, respectively (p < 0.001).

CONCLUSIONS

Endosolv-R was a significantly more effective short term softener for all the tested sealers after 2 min whereas Xylene was an effective short term softener against AH plus and Adseal but less effective against AH 26.

Antimicrobial activity of essential oils and chloroform alone and combinated with cetrimide against Enterococcus faecalis biofilm

The Enterococcus faecalis bacteria have been identified as the most commonly recovered species from teeth with persistent endodontic infections. The antimicrobial activity of essential oils and chloroform (CHL), alone and in association with various concentrations of cetrimide (CTR), against biofilm of Enterococcus faecalis was investigated. Solutions of CHL, eucalyptus oil (EO) and orange oil (OO) associated with CTR at 0.3%, 0.2%, 0.1%, and 0.05% were used to determine antimicrobial activity by exposing treated bovine dentine blocks to E. faecalis. Biofilms grown in the dentine blocks for 7 days were exposed to solutions for 2 and 5 min. Biofilm reduction between OO and EO at 2 min did not show any significant differences; however, OO had a higher kill percentage of biofilms than did the eucalyptus oil at 5 min (p < 0.01). Combinations with CTR at all concentrations achieved a 100% kill rate at 2 and 5 min. The association of CTR with solvent agents achieved the maximum antimicrobial activity against E. faecalis biofilms in dentine.

Dissolving efficacy of different organic solvents on gutta-percha and resilon root canal obturating materials at different immersion time intervals

Background Aim:

The purpose of this study was to compare and evaluate the dissolving capability of various endodontic solvents used during endodontic retreatment on resilon and gutta-percha at different immersion time intervals.

Materials and Methods:

160 ISO no. 40 cones (0.06 taper), 80 each of resilon and gutta-percha were taken as samples for the study. Both resilon and gutta-percha were divided into eight experimental groups of 20 cones (four groups each of resilon and gutta-percha) for immersion in xylene, tetrachloroethylene, refined orange oil and distilled water. Each group was further divided into two equal subgroups (n=10) for 2- and 5-minute immersion time intervals at room temperature to investigate the potential of these solvents for clinical use in dissolving resilon and gutta-percha. Each sample was weighed initially before immersing in the solvent on a digital analytical scale. Distilled water served as a control. Samples were removed from the respective solvents after the specified immersion period and washed in 100 ml of distilled water and allowed to dry for 24 h at 37°C in a humidifier. The samples were then again weighed after immersion in the specific solvent on a digital analytical scale. The extent of gutta-percha or resilon removed from the specimen was calculated from the difference between the original weight of gutta-percha or resilon sample and its final weight. Means and standard deviations of percentage loss of weight were calculated at each time interval for each group of specimens. The values were compared by statistical parametric tests using SPSS 16.0 Software. The data was subjected to paired ‘t‘ test, independent ‘t’ test, one-way ANOVA test and multiple comparisons with Scheffe's test.

Results:

There was no significance in the amount of gutta-percha dissolved at 2- and 5-minute immersion time intervals in all groups (P>0.05) except the tetrachloroethylene group (P=0.00). There was a very high significance in the amount of resilon dissolved at 2- and 5-minute immersion time intervals in all groups (P=0.00) except the xylene and distilled water (Control) groups (P>0.05).

Conclusion:

The results showed that xylene, refined orange oil and tetrachloroethylene can be used for softening gutta-percha/resilon during retreatment with various techniques- xylene being the best solvent both for gutta-percha and resilon.

Influence of different organic solvents on degree of swelling of poly (dimethyl siloxane)-based sealer

The study evaluated the compatibility of chloroform, ether, and xylene with poly(dimethyl siloxane) (PDMS) based sealer. Freshly mixed sealer was placed in 90 glass molds with 5 mm diameter and 2 mm thickness. All samples were stored in 75% relative humidity at 37°C for 2 weeks. All the samples were divided into three groups: group A - chloroform; group B - ether, and group C - xylene and immersed in fresh solvent at room temperature. The specimens were weighed before and after immersion for each group at the end of 2, 5, and 10 min. The swelling ratio was calculated for all the groups. Intergroup comparison revealed no difference in the mean swelling ratio for 2, 5, and 10 min (P > 0.001; Tukey HSD Post Hoc). Intragroup comparison revealed significant difference in swelling ratio between 2 and 5 min for group B and group C (P < 0.001; Paired t test). Ether has the highest compatibility with PDMS-based sealer after 2 min followed by xylene after 5 min.

Retreatment efficacy of the Epiphany soft resin obturation system

AIM

To assess the efficacy of retreatment of canals filled with the Epiphany System with and without solvent, with particular reference to the extent of canal enlargement during retreatment.

METHODOLOGY

Sixty roots with canals prepared to apical size 45 were embedded in resin blocks and sectioned vertically. Digital micrographs of canal walls were captured. Roots were re-assembled and filled with Epiphany/Resilon (experimental) or gutta-percha/AH Plus (control). After 8 weeks, canals were retreated to size 45 with or without chloroform, and the time recorded. Roots were split, imaged, re-assembled, retreated to size 55, split and imaged. Root-filling residue, traced at three canal levels, was expressed as percentage of canal surface.

RESULTS

Residue percentage was greater (t-test, P < 0.01) in the experimental group than in the control. Most residue in all specimens was in the apical third (ANOVA, P < 0.01). Chloroform and enlargement to size 55 decreased residue in both groups (t-test, P < 0.01). Retreatment time was longer in the experimental group (P < 0.05), and reduced by chloroform in both groups (P < 0.05).

CONCLUSIONS

The Epiphany System was retreatable with and without chloroform, with lesser efficacy than gutta-percha and AH Plus sealer.

Surgical versus non-surgical endodontic re-treatment for periradicular lesions

BACKGROUND

Though success rates of endodontic initial treatment have been improving over the years, persistence of periapical disease is far from being a rare condition. The most common therapeutical options for the re-treatment of teeth with periapical pathosis are non-surgical orthograde treatment and surgical treatment. Selection between alternative treatments should be based on assessment of respective benefits (mainly healing) and risks from studies consistent with a high level of evidence.

OBJECTIVES

To test the null hypothesis of no difference in outcome between surgical and non-surgical therapy for endodontic re-treatment of periradicular lesions.

SEARCH STRATEGY

The Cochrane Oral Health Group Trials Register, CENTRAL, MEDLINE and EMBASE were searched with appropriate search strategies. Handsearching included eight dental journals. The bibliographies of relevant clinical trials and relevant articles were checked for identifying studies outside the handsearched journals. Seven manufacturers of instruments in the field of endodontics or endodontic surgery or both, as well as the authors of the identified randomised controlled trials (RCTs) were contacted in order to identify unpublished or ongoing RCTs. No language restriction was placed. The last electronic search was conducted on 3rd April 2007.

SELECTION CRITERIA

All RCTs about re-treatment of teeth with periapical pathosis in which both surgical and non-surgical approaches were used and having a follow up of at least 1 year were considered for the analysis.

DATA COLLECTION AND ANALYSIS

A quality assessment of the included RCTs was carried out and the authors were contacted for missing information. We independently extracted the data in duplicate. We followed the Cochrane Oral Health Group's statistical guidelines.

MAIN RESULTS

Three RCTs were identified, two of them reporting different data from the same clinical study. The risk of bias was judged as moderate for one study and high for the other one. 126 cases were followed up for at least 1 year, and 82 had a follow up of 4 years. At the 1-year follow up the success rate for surgical treatment was slightly better than non-surgical (risk ratio (RR) 1.13; 95% confidence interval (CI) 0.98 to 1.30). When the follow up was extended to 4 years (only one RCT made it) the outcome for the two procedures became similar.

AUTHORS' CONCLUSIONS

The finding that healing rates can be higher for cases treated surgically as compared to those treated non-surgically, at least in the short term, is based on two RCTs only. A single RCT reported that in the medium to long term healing rates for the two procedures are very similar. There is currently scarce evidence for a sound decision making process among alternative treatments for the re-treatment of a periradicular pathosis. More well-designed RCTs should be performed with follow up of at least 4 years, and with a consistent sample size, to detect a true difference in the long term between the outcomes of the two alternative treatments, if any exist.

In vitro study of effect of solvent on root canal retreatment

The aim of this study was to assess the effectiveness of five different solvents: xylol, eucalyptol, halothane, chloroform and orange oil on softening gutta-percha in simulated root canals. One drop of solvent was placed into a reservoir made in a simulated canal whose channel was previously instrumented and filled with gutta-percha and N-Rickert sealer. After 5 min, softening was evaluated for each solvent by the penetration of a spreader while applying force with a 442 Instron apparatus to reach a depth of 5 mm. The results were analyzed statistically by the Kruskal-Wallis test. Xylol and orange oil were better in softening gutta-percha than the other solvents. There was no significant difference between xylol and orange oil, but these were statistically different from eucalyptol, halothane and chloroform (p < 0.01).