Introduction: The purpose of this clinical study was to compare the blood mercury levels before and after endodontic surgery using amalgam as a root-end filling material. Materials and Methods: Fourteen patients requiring periradicular surgery participated in this prospective clinical study. A zinc-free amalgam was employed as root-end filling material. Blood samples were collected at three intervals: immediately before, immediately after and one week postoperatively. Mercury content of the blood was determined using gold amalgamation cold-vapor atomic absorption spectrometry. Obtained data were analyzed using analysis of variance for repeated measures and paired t-test. Results: The mean (SD) of blood mercury levels was 2.20 (0.24) ng/mL immediately before surgery, 2.24 (0.28) ng/mL immediately after surgery and 2.44 (0.17) ng/mL one week after the periradicular surgery. The blood mercury level one week post-operative was significantly higher than both blood mercury levels immediately before (P&lt;0.001) and immediately after (P=0.005) the surgery. Conclusion: Placement of an amalgam retroseal during endodontic surgery can increase blood mercury levels after one week. The mercury levels however, are still lower than the toxic mercury levels. We suggest using more suitable and biocompatible root-end filling materials

Nazeri, Mohsen

Saatchi, Masoud

Shadmehr, Elham

Talebi, Seyed Morteza

English

PubMed

Journals Portal, Shahid Beheshti University of Medical Sciences

IEJ Iranian Endodontic Journal 2013;8(3):85-88A Prospective Clinical Study on Blood Mercury LevelsFollowing Endodontic Root-end Surgery with AmalgamMasoud Saatchi a, Elham Shadmehra*, Seyed Morteza Talebi b, Mohsen Nazeri ca Torabinejad Dental Research Center, Department of Endodontics, Dental School, Isfahan University of Medical Sciences, Isfahan, Iran; b Department ofChemistry, Isfahan University, Isfahan, Iran; c Private Practice, Isfahan, IranARTICLE INFO ABSTRACTArticle Type:Original ArticleIntroduction: The purpose of this clinical study was to compare the blood mercurylevels before and after endodontic surgery using amalgam as a root-end filling material.Materials and Methods: Fourteen patients requiring periradicular surgery participatedin this prospective clinical study. A zinc-free amalgam was employed as root-end fillingmaterial. Blood samples were collected at three intervals: immediately before,immediately after and one week postoperatively. Mercury content of the blood wasdetermined using gold amalgamation cold-vapor atomic absorption spectrometry.Obtained data were analyzed using analysis of variance for repeated measures and pairedt-test. Results: The mean (SD) of blood mercury levels was 2.20 (0.24) ng/mLimmediately before surgery, 2.24 (0.28) ng/mL immediately after surgery and 2.44 (0.17)ng/mL one week after the periradicular surgery. The blood mercury level one week post-operative was significantly higher than both blood mercury levels immediately before(P<0.001) and immediately after (P=0.005) the surgery. Conclusion: Placement of anamalgam retroseal during endodontic surgery can increase blood mercury levels afterone week. The mercury levels however, are still lower than the toxic mercury levels. Wesuggest using more suitable and biocompatible root-end filling materials.Keywords: Dental Amalgam; Endodontics; Mercury; Root Canal Filling Materials; OralSurgeryReceived: 18 Dec 2012Revised: 09 Mar 2013Accepted: 29 Mar 2013*Corresponding author: ElhamShadmehr, Dental School, IsfahanUniversity of Medical Sciences,Isfahan, Iran. Zip code: 8174755153.Tel: +98-311 6250955Fax: +98-311 6250955Email: elham.shadmehr@gmail.comIntroductioneriradicular surgery is an important adjunct toorthograde root canal therapy. When non-surgicaltreatment fails or cannot be performed, surgicalapproach is indicated [1, 2]. Apical surgery usually consists ofperiapical curettage followed by root-end resection, cavitypreparation, and filling. A retrograde filling material isusually used to seal the root-end cavity and preventmicroleakage. A good quality root-end filling is essential for asuccessful endodontic surgery [3].The ideal root-end filling material should bebiocompatible, bioinductive, bactericidal or at leastbacteriostatic, insoluble in tissue fluids, dimensionally stable,easy to use, radiopaque, non-toxic, non-carcinogenic, andnot corrosive. It should also be electrochemically inactive,and non-staining. It should have excellent sealing ability andpromote regeneration of the original tissues [4]. Although,the ideal material is yet to be found, a number of materialshave been suggested for root-end filling including amalgam,composite resin, glass ionomer cement, gold foil, gutta-percha, reinforced zinc oxide eugenol based cement, mineraltrioxide aggregate (MTA), and calcium enriched mixture(CEM) cement [5-8].Amalgam has been a frequently used root-end fillingmaterial; it is easy to use, radiopaque and non-resorbable [9].The characteristics of amalgam as a root-end filling materialsuch as marginal adaptation [10], sealing ability [11],cytotoxicity [12] and biocompatibility [5] have beenevaluated. Some concerns have been expressed regarding therelease of mercury from amalgam into the bloodstream [13].Mercury is the most harmful of all heavy metals; moreover,can change the distribution and retention of other heavymetals [14]. It is a very reactive metal that has manyrecognized toxic properties at high doses including cerebellarataxia, paresthesia, dysarthria, and constriction of the visualPSaatchi et al.86IEJ Iranian Endodontic Journal 2013;8(3):85-88Table 1. The minimum, maximum, mean (SD) of blood mercury levels of subjects at three intervals (ng/mL)Interval Min. Max. Mean (SD)Immediately before the surgery 1.8 2.6 2.2 (0.24)Immediately after the surgery 1.9 2.7 2.24 (0.28)One week after the surgery 2.1 2.7 2.44 (0.17)fields [15]. Mercury may also be a risk factor in multiplesclerosis [16] and Alzheimer's disease [17].In spite of studies that evaluate the release of mercuryions from amalgam restorations into the blood or urine [18-20], there have been few studies evaluating the blood mercurylevels following amalgam root-end filling materials [21, 22].Since amalgam retroseals have a direct contact withperiradicular tissue fluids, they may release mercury in adifferent pattern compared with amalgam restorations. In thisprospective clinical study, we aimed to evaluate the bloodmercury levels immediately before, immediately after, and oneweek following the placement of freshly mixed amalgam as aroot-end filling material using gold amalgamation cold-vaporatomic absorption spectrometry method (GA-CVAAS).Material and MethodsThe study consisted of 15 patients who were referred forsurgical endodontic treatment to the Department ofEndodontics, School of Dentistry, Isfahan University ofMedical Sciences, Iran. The Ethics Committee of theUniversity approved the protocol of the study. Writteninformed consent was obtained from all patients. Patientswho were older than 18 years with no physician-diagnosedimmunosuppressive, neurological, psychological, behavioral,or renal disorders, and had a tooth requiring periradicularsurgery were included in the study. Subjects who are exposedto mercury in their job like dentists, stonemason, and mineworkers were not included in the study. Patients who usedalcohol and cigarette or tobacco chewing habit during thestudy, ate seafood one week before and during the study,took medications that might affect mercury assessment, wereexcluded from the study. Patients were all required toprovide informed consent if they were to take part in thestudy. One patient was excluded due to the reasons above.Surgical procedureThe teeth were treated by a senior specialist. Root-endresection was performed with an International Organizationfor Standardization (ISO) #14 sterile tapered fissure bur(Maillefer, Ballaigues, Switzerland) using a straighthandpiece and sterile saline coolant. Approximately, 3 mm ofthe root-end was resected as close to 90° to the long axis ofthe root. Root-end preparation was performed usingultrasonically powered tips numbers E31D or E32D (NSKVarios 750, Nakanishi, Tochigi, Japan). Approximately, a 3-mm deep cavity was prepared. In all the surgical treatmentszinc free amalgam (Tytin Kerr Sybron, Romulus, MI, USA)was used. For each subject, blood samples were collected inthree intervals of immediately before and immediately afterthe surgery, and also one week later. In each interval 10 mLblood was drawn and coded using single blind protocol.Mercury analysisThe blood samples were mixed with 0.5 mL of 1% EDTA(Merck, Darmstadt, Germany) anticoagulant agent and keptfrozen at -20°C. A method based on GA-CVAAS was used forthe determination of trace mercury (Hg+2) in the bloodsamples. This method was developed for ultra-trace mercurydetermination [23, 24]. Determinations were done on aShimadzu model AA-6601F single beam atomic absorptionspectrometer (Nakagyo-Ku, Kyoto, Japan) and calculated asnanogram per milliliter (ng/mL).Statistical AnalysisThe data were analyzed using SPSS software, version 15(SPSS Inc, Chicago, IL). Analysis of variance for repeatedmeasures was used to compare the blood mercury levels ofpatients at three intervals, followed by paired t-test. Statisticalsignificance was defined at P<0.05.ResultsOne patient was excluded as he did not have the necessarycriteria. Of the 14 patients selected in our study, 8 were menand 6 were women. Their age ranged from 27-56 years witha mean age of 40 years. The individual and the mean(standard deviation) blood mercury levels of patients atthree intervals are shown in Table 1. There was nosignificant difference between the total blood mercurylevels immediately before and immediately after the surgery(P=0.315). One week after surgery, the total mercuryconcentration in the blood was significantly higher thanboth immediately before (P<0.001) and immediately afterthe surgery (P=0.005).DiscussionMercury can be found in three basic forms of elemental,inorganic, and organic. Dental amalgams are one of the mostcommon sources of elemental mercury. Amalgam mercury ismethylated to organic mercury in the oral cavity and/orgastro-intestinal tract [25, 26]. Fish and sea mammals are thesources of organic mercury in the form of methyl and ethylmercury. Inorganic mercury is the toxic species found inhuman tissue after conversion from the other forms [27]. Theinvestigations about the effects of mercury content of dentalamalgam are still ongoing [28].Mercury blood levels87IEJ Iranian Endodontic Journal 2013;8(3):85-88Dental amalgam is composed of 50% mercury, 25% silver,25% tin, copper, and nickel. It has been the main source ofhuman exposure to mercury [26, 28]. Also, amalgam hashistorically been the most widely used root-end filling materialfor more than a century [29]. It is economical and easy tomanipulate. However, it has several disadvantages includingcorrosion, electrolysis, delayed expansion, marginal leakage,and causing tissue tattoos [30, 31]. Mercury toxicity has been afurther deterrent to the selection of amalgam as a restorationand/or root-end filling material [32].In our study, a significant elevation of blood mercurylevels was seen in the patients following the placement ofamalgam root-end fillings. Our results do not coincide withprevious studies [21, 22]. Longos et al. reported baselineblood and urine mercury levels for 10 female baboons thatunderwent root end surgery with amalgam. They assessedamalgam levels using cold vapor atomic absorptionspectrometry method (CVAAS) [21]. Blood and urinesamples were monitored at the time of surgery and at 24hours, 48 hours, 1 week, 2 weeks, 1 month, and 2 monthsafter surgery. They found that mercury was undetectable inthe majority of samples. In a few samples, they found barelydetectable levels of mercury. They concluded that mercuryreleases from retrograde amalgam fillings is of little concern.Skoner et al. analyzed blood mercury level of 10 patientsrequiring endodontic surgery using an amalgam retroseal[22]. They measured blood mercury levels using CVAAS atfour intervals of one week before surgery, at the time ofsurgery, one week after surgery, and one month after surgery.They reported that placement of amalgam retroseals did notincrease the blood mercury levels significantly. Thedifference between the findings of our study and two otherstudies may be because of the using different techniques fordetection of blood mercury levels. Although the CVAASmethod is effective, popular, and widely accepted for thedetermination of mercury in biomedical samples, the GA-CVAAS method offers a lower detection limit and highsensitivity [24, 33] therefore we used GA-CVAAS methodwhich is more accurate. The method is able to determine theultra trace amount of mercury. Also, we did not include thepatients who smoked or consumed alcohol. Tobacco smokecan increase the absorption of mercury because cigarettesmoking may be a substantial source of intake of hazardouselements such as mercury [34]. Alcohol depresses oxidationand retention of mercury in most organs and whole body andthus increase blood level of mercury [35].The mean blood mercury level was 2.44±0.17 ng/mL atone week after the surgery which was significantly more thanthe mean blood mercury levels immediately before andimmediately after the surgery. The normal blood mercurylevel is considered to be in the range of 0-5 ng/mL. Toxicblood mercury level is reported to be 200 ng/mL and thelethal level to be 600 ng/mL [22, 36]. In our study themaximum blood mercury level was 2.7 ng/mL; this value iswithin normal range. However, the release of mercury fromamalgam retroseal may continue and potentially threaten thehealth of individuals. Therefore, we suggest using moresuitable root-end filling materials [8, 37]. Because the resultsof our study show increased blood mercury level at one weekafter the surgery, we also recommend long-term studies onthis subject.A total of 20 mL blood was drawn for each patient in 2intervals of immediately before and immediately after thesurgery. To prevent blood pressure related problems, onlyhealthy individuals should be selected.ConclusionIn conclusion, based on the results of this clinical study,mercury is released from amalgam after endodontic surgeryas a root-end filling material. Although the amount ofmercury released is smaller than the toxic mercury levels,amalgam retroseals may release this heavy metal over time.AcknowledgmentsThis study was supported by Isfahan University of MedicalSciences Research Grant #79275.Conflict of Interest: ‘None declared’.References[1] Setzer FC, Shah SB, Kohli MR, Karabucak B, Kim S. Outcome ofendodontic surgery: a meta-analysis of the literature--part 1:Comparison of traditional root-end surgery and endodonticmicrosurgery. 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SCIENTIAIRANICA. 2008;15(4):418-21.[34] Chiba M, Masironi R. Toxic and trace elements in tobaccoand tobacco smoke. Bull World Health Organ. 1992;70(2):269-75.[35] Khayat AI, Shaikh ZA. Dose-effect relationship betweenethyl alcohol pretreatment and retention and tissue distributionof mercury vapor in rats. J Pharmacol Exp Ther.1982;223(3):649-53.[36] Paksoy CS, Gorgun S, Nalcaci R, Yagbasan A. Assessmentof blood mercury levels in practicing Turkish clinicians, dentalstudents, and dental nurses. Quintessence Int. 2008;39(4):e173-8.[37] Asgary S, Eghbal MJ, Ehsani S. Periradicular regenerationafter endodontic surgery with calcium-enriched mixture cementin dogs. J Endod. 2010;36(5):837-41.Please cite this paper as: Saatchi M, Shadmehr E, Talebi SM,Nazeri M. A Prospective Clinical Study on Blood MercuryLevels Following Endodontic Root-end Surgery withAmalgam. Iran Endod J. 2013;8(3):85-8.

A Prospective Clinical Study on Blood Mercury Levels Following Endodontic Root-end Surgery with Amalgam

http://www.ncbi.nlm.nih.gov/pubmed/23922566

A Prospective Clinical Study on Blood Mercury Levels Following Endodontic Root-end Surgery with Amalgam

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