The antimicrobial effect of calcium hydroxide in root canals pretreated with 5% iodine potassium iodide

Calcium hydroxide (CH) is often used as a routine interappointment dressing during the endodontic treatment of teeth with apical periodontitis. However, it fails to consistently produce sterile root canals. The present study was set up to find out whether an antimicrobial strategy including the use of CH could be made more effective if: 1) canals were pretreated with 5% iodine potassium iodide (IPI), and 2) the dressing period was extended up to 2 months. Fifty human teeth, with radiographically verified apical periodontitis, were microbiologically sampled. After chemomechanical preparation the canals were pretreated with IPI for 3-7 days. Teeth where microorganisms persisted were then treated with CH for 2 months. Following instrumentation and dressing with IPI, 43 bacterial strains were recovered in 22 of the teeth. Samples obtained after the CH dressing period disclosed growth of 13 facultative and two strict anaerobic strains in 10 teeth. Enterococcus faecalis was identified in two specimens. In conclusion, the present study gave no evidence for an increased antimicrobial effect of CH if it was left for longer periods in the root canal. Although pretreatment with IPI from a quantitative point of view did not seem to add antimicrobial power, it might reduce the frequency of persisting strains of E. faecalis.     

The diagnostic accuracy of microbiologic root canal sampling and the influence of antimicrobial dressings

Reit C, Molander A, Dahlén G. The diagnostic accuracy of microbiologic root canal sampling and the influence of antimicrobial dressings. Endod Dent Traumatol 1999; 15: 278–283.© Munksgaard, 1999.
Abstract — The routine approach to endodontic treatment of teeth with apical periodontitis often involves an interappointment dressing with calcium hydroxide. However, investigations have demonstrated a negative influence of calcium hydroxide on the accuracy of microbiological root canal sampling (MRS). The aim of the present study was to investigate whether the use of a fluid dressing like 5% iodine potassium iodide (IPI) would increase the accuracy of MRS. Following instrumentation of 50 teeth with radiographically verified apical periodontitis the root canals received IPI as an intra-canal dressing. One week after closure canals were sampled, "test sample" (TS), and then left filled with sampling fluid and temporarily sealed. Seven days later a "gold standard" (GS) sample was obtained. Bacteria were recovered in 22 teeth (44%) in TS as well as in GS. Fifteen teeth (30%) were positive for growth in both samples. Using the detection level "very sparse growth" of microbes the sensitivity and specificity of MRS reached 68% and 75%, respectively. In an earlier study, following the same experimental protocol, but with calcium hydroxide as intracanal dressing, the corresponding values were 33% and 81%. In 25% of these cases bacteria persisted in the canals. As compared to calcium hydroxide, the use of IPI resulted in improved test accuracy, but loss of antibacterial capacity. Conclusively, intracanal dressings seem to vary in their influence on the microbiologic test performance as well as in their antibacterial efficacy. In a clinical situation the choice of interappointment dressing should include consideration of these potentially conflicting properties.     

Isolation of yeasts and enteric bacteria in root-filled teeth with chronic apical periodontitis

AIMS: The aim of this study was to determine the occurrence and role of yeasts, enteric gram-negative rods and Enterococcus species in root-filled teeth with chronic apical periodontitis, and the antimicrobial effect of iodine potassium iodide (IKI) irrigation. METHODOLOGY: Forty symptom-free root-filled teeth with chronic apical periodontitis were included in the study. The patients were divided into two groups. In group A the canals were filled with calcium hydroxide for 10-14 days after cleaning and shaping; in group B the canals were irrigated with IKI for 5 min after cleaning and shaping followed by a permanent root filling. Microbiological samples were taken from the canals before and after the chemomechanical preparation and after iodine irrigation (group B). RESULTS: Microbes were isolated from 33 of 40 teeth in the initial sampling. Yeasts were isolated from six teeth, three of them together with E. faecalis. Enteric rods (Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis) were present in three teeth and E. faecalis was isolated from 21 of the 33 culture positive teeth, 11 in pure culture. Growth was detected in 10 teeth of the second samples. Six of the 10 cases were E. faecalis, with five being a pure culture. All third samples (after IKI) except one were negative. The number of microbial cells per sample did not correlate with lesion size. Two flare-ups were recorded, both in teeth with a mixed infection. CONCLUSION: The high prevalence of enteric bacteria and yeasts in root-filled teeth with chronic apical periodontitis was established. IKI improved the antimicrobial effect of the treatment.     

Clinical investigation of the effect of calcium hydroxide intracanal dressing on bacterial lipopolysaccharide reduction from infected root canals

The purpose of this clinical study was to determine the effect of 7 day intracanal dressing with calcium hydroxide on the amount of bacterial lipopolysaccharide (LPS; endotoxin) in human teeth with necrotic and infected pulp and apical periodontitis. Twenty‐five single‐rooted teeth with necrotic pulps and apical periodontitis were selected. Samples were collected before (S1), after root canal preparation (S2) and after 7 day intracanal dressing with calcium hydroxide (S3). The limulus amoebocyte lysate assay was used to quantify LPS. LPS was present in 100% of the root canals before (S1), after preparation (S2) and after 7 day intracanal dressing (S3). A significant reduction, equal to 29.54%, was found after root canal preparation (P < 0.05). A significant difference (equal to 25.26% reduction) was also detected between S2 and S3 (P < 0.05). Total endotoxin reduction (S3 compared with S1) was found to be 47.34%. Endotoxin concentration of the infected root canals was reduced after root canal preparation and also after 7 days of dressing of canals with calcium hydroxide; however, relatively high values of endotoxin remained in the root canals.     

Influence of irrigation and intracanal dressing on the healing process of dogs' teeth with apical periodontitis

Abstract Dogs’ teeth with apical periodontitis were treated endodontically, Dakin's solution being used in an experimental group as the irrigation solution, and camphorated paramono-chlorophenol as an intracanal dresssing. For a second group of teeth, the irrigation solution used was physiologic saline, dry cotton only being placed into the pulpal chamber to take the place of an intracanal dressing. In a second visit, overinstrumentation and a new application of the same kind of dressing were performed, the root canals being then filled with gutta-percha cones and zinc oxide-eugenol cement. Other specimens were treated, in one visit, where physiologic saline or Dakin's solution were the irrigation solutions. The animals were sacrificed 6 months after the obturation of the root canals. Histologic exams showed better results for the experimental group where Dakin's solution and camphorated paramonochlorophenol had been used, with signs of repair characterized by newly formed cementum and bone tissue, as well as a marked reduction in size of the periapical lesions. No differences were seen in the results with physiologic saline or Dakin's solution as irrigants.     

Survival of Enterococcus faecalis in root canals ex vivo

AIM: The hypotheses tested in this study were that: (i) Enterococcus faecalis can survive long-term entombment in root filled teeth without additional nutrients, (ii) initial cell density influences the survival of E. faecalis in instrumented root canals and (iii) gelatinase-production capacity influences the survival of E. faecalis in root canals. METHODOLOGY: The root canals of 150 extracted single canal teeth were instrumented to apical size 60 and divided into six groups of 25. Within each group 10 canals were inoculated with either gelatinase-producing E. faecalis OG1-S and the other 10 with its gelatinase-defective mutant E. faecalis OG1-X. Five canals per group were kept as uninoculated controls. The root canals in groups 1 and 2 were inoculated with 10(6) bacteria, incubated for 48 h at 37 degrees C then filled with gutta-percha and zinc-oxide eugenol sealer. Root canals were inoculated with 10(6), 10(5), 10(4) and 10(3) bacteria in groups 3-6, respectively, and left unfilled. All teeth were sealed coronally with glass-ionomer cement. After 6- (groups 1, 3-6) and 12-month (group 2) incubation at 37 degrees C in 100% humidity, root fragments were analysed for presence of E. faecalis, using culture, polymerase chain reaction and histological methods. RESULTS: Viable E. faecalis was recovered from all root filled teeth and from 95-100% of unfilled inoculated teeth. Initial cell density and gelatinase production did not influence the recovery of viable E. faecalis (P > 0.05; chi-square test). Enterococcus faecalis 16S rRNA gene products were present in all inoculated teeth and absent in all noninoculated controls. Dentinal tubule infection was evident under light microscopy in sections from inoculated teeth after 48-h, 6- and 12-month incubation. CONCLUSIONS: Enterococcus faecalis inoculated into root canals maintained viability for 12-months ex vivo. The clinical implications are that viable E. faecalis entombed at the time of root filling could provide a long-term nidus for subsequent infection.     

A big role for the very small—understanding the endodontic microbial flora

Apical periodontitis, an inflammatory process around the apex of a tooth root, is primarily a sequel to microbial infection of the pulp space. The microbial flora is composed of a restricted group of the total oral flora, selected by environmental pressures of anaerobiosis, nutrition and competition with other species and inhabits the root canal as a biofilm of coaggregated communities in an extracellular matrix. The untreated infected canal is generally composed of a polymicrobial mix with approximately equal proportions of Gram-positive and Gram-negative species, dominated by obligate anaerobes.
The type of microbial flora in the root-filled tooth with persistent apical periodontitis has very different characteristics. These infections are characterized by one or just a few species, predominantly Gram-positive micro-organisms with an equal distribution of facultative and obligate anaerobes. Enterococcus faecalis has been a conspicuous finding in most studies.
Because the primary aetiological problem is infection, endodontic treatment is directed at control and elimination of the root canal flora by working in a sterile way. Based on current knowledge, the best available method for obtaining clean, microbe-free root canals is by instrumentation with antimicrobial irrigation reinforced by an intracanal dressing with calcium hydroxide.     

四种浓度次氯酸钠根管消毒效果的评价

目的 探讨4种浓度次氯酸钠对感染根管的消毒作用.方法 将100例慢性根尖周炎患者随机分为5组,分别使用0.25%、0.50%、1.00%、2.00%的次氯酸钠和生理盐水作为根管冲洗剂,根管预备前后,分离、培养根管内厌氧菌,观察并记录细菌形态及菌落数.结果 4种浓度次氯酸钠对感染根管均有消毒作用,生理盐水的根管消毒作用差.结论 在橡皮障未能普及的情况下,作为根管冲洗剂的次氯酸钠合适浓度为1.00%.     

Phenotypic and genotypic identification of enterococci isolated from canals of root-filled teeth with periapical lesions

The objectives of the present study were to identify enterococcal species isolated from the canals of root-filled teeth with periapical lesions using biochemical and molecular techniques, and to investigate the genetic diversity of the isolates. Twenty-two Enterococcus strains, isolated from the canals of root-filled teeth with persisting periapical lesions, were identified to species level using rapid ID 32 STREP galleries and partial 16S rDNA sequencing. To subtype the strains, genomic DNA from the isolates was analyzed by pulsed field gel electrophoresis (PFGE) after digestion with SmaI. Intragenic regions of two genes, ace and salA, were sequenced for further differentiation of the isolates. All strains were identified as Enterococcus faecalis by both commercial kit and partial 16S rDNA sequencing. PFGE with SmaI of 22 isolates demonstrated 18 macrorestriction profiles, whereas 13 distinct genotypes were identified after analysis of the ace and salA composite sequences. Most of the isolates from distinct patients had different PFGE profiles. Moreover, in two cases, different E. faecalis strains were found in different root-filled teeth from the same mouth. E. faecalis was the only enterococcal species isolated from the canals of root-filled teeth with periapical lesions. Genetic heterogeneity was observed among the E. faecalis isolates following PFGE and sequence-based typing method. Furthermore, the genetic diversity within root canal strains was similar to previous reports regarding E. faecalis isolates from different clinical and geographic origins.     

The diagnostic accuracy of microbiologic root canal sampling and the influence of antimicrobial dressings

The routine approach to endodontic treatment of teeth with apical periodontitis often involves an interappointment dressing with calcium hydroxide. However, investigations have demonstrated a negative influence of calcium hydroxide on the accuracy of microbiological root canal sampling (MRS). The aim of the present study was to investigate whether the use of a fluid dressing like 5% iodine potassium iodide (IPI) would increase the accuracy of MRS. Following instrumentation of 50 teeth with radiographically verified apical periodontitis the root canals received IPI as an intracanal dressing. One week after closure canals were sampled, "test sample" (TS), and then left filled with sampling fluid and temporarily scaled. Seven days later a "gold standard" (GS) sample was obtained. Bacteria were recovered in 22 teeth (44%) in TS as well as in GS. Fifteen teeth (30%) were positive for growth in both samples. Using the detection level "very sparse growth" of microbes the sensitivity and specificity of MRS reached 68% and 75%, respectively. In an earlier study, following the same experimental protocol, but with calcium hydroxide as intracanal dressing, the corresponding values were 33% and 81%. In 25% of these cases bacteria persisted in the canals. As compared to calcium hydroxide, the use of IPI resulted in improved test accuracy, but loss of antibacterial capacity. Conclusively, intracanal dressings seem to vary in their influence on the microbiologic test performance as well as in their antibacterial efficacy. In a clinical situation the choice of interappointment dressing should include consideration of these potentially conflicting properties.     

Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions

AIM: This prospective clinical study explored the influence of calcium hydroxide as an interappointment dressing on the healing of periapical lesions associated with pulpless teeth that had not been endodontically treated previously. This was achieved by comparing the prognosis after a two-visit root canal treatment with that following a one-visit treatment. METHODOLOGY: Seventy-three patients were recruited having one tooth with an endodontically induced lesion. Of these patients, 67 could be re-examined. Calcium hydroxide was placed in the instrumented root canals of 31 teeth for at least one week and the treatment finished at the second visit. Thirty-six teeth were root canal treated at one visit. The criteria for success were the absence of signs and symptoms indicating an acute phase of periapical periodontitis and radiographically a periodontal ligament space of normal width. Methods for event time analysis were used to evaluate and compare the prognosis of both treatment approaches. RESULTS: The probability that complete periapical healing will take place increased continuously with the length of the observation period. In both treatment groups the likelihood that the root canal treatment yields a success within an observation time of five years exceeded 90%. A statistically significant difference between the two treatment groups could not be detected. CONCLUSIONS: From a microbiological perspective, one-visit root canal treatment created favourable environmental conditions for periapical repair similar to the two-visit therapy when calcium hydroxide was used as antimicrobial dressing. One-visit root canal treatment is an acceptable alternative to two-visit treatment for pulpless teeth associated with an endodontically induced lesion.     

Apical periodontitis development and bacterial response to endodontic treatment. Experimental root canal infections in monkeys with selected bacterial strains

In six monkeys, 160 root canals were inoculated with a combination of four bacterial strains belonging to species Streptococcus milleri, Peptostreptococcus anaerobius, Prevotella oralis, and Fusobacterium nucleatum. In two other monkeys, 24 root canals were inoculated with a five-strain combination consisting of these strains and a strain of Enterococcus faecalis. All strains were previously isolated from an infected monkey root canal. After 8-12 months, survival of the strains was recorded bacteriologically, and the reaction in the periapical region was radiographed. From 180 of 184 root canals, one or more of the bacterial strains were reisolated. The two facultative strains were more frequently reisolated than the anaerobic strains. Apical periodontitis was registered in the periapical region of more than 96% of root canals with reisolated bacteria but in none of those without reisolated bacteria. Endodontic treatment was carried out in two sessions with an interval of 14 d without interappointment dressings, and the effect was evaluated bacteriologically before and after each treatment. The chemo-mechanical treatment reduced significantly the number of strains and bacterial cells. The facultative bacteria were more resistant to the treatment than the anaerobic bacteria. The five-strain combination had a higher survival rate than the four-strain combination.     

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目的对比观察氢氧化钙和甲醛甲酚用于根尖周炎患牙根管内封药的疗效。方法选择2008年1月到2009年12月在中国医学科学院整形外科医院口腔中心就诊的135例牙根尖周炎患者的156颗患牙,随机分为A组(81颗)和B组(75颗)。步退法根管预备后分别于根管内封入氢氧化钙(A组)和甲醛甲酚(B组)进行消毒。于封药后1周、根充后1周和治疗后3个月对两组疗效进行观察并作出相应评价。结果根管封药后1周A组的有效率为92.59%,B组的有效率为78.67%,两组间差异有统计学意义(P<0.05);根管充填后1周,A、B两组的急症发生率(3.70%对12.0%)差异有统计学意义(P<0.05)。治疗后3个月A组的成功率为91.36%;B组为84.00%,两组间差异有统计学意义(P<0.05)。结论氢氧化钙用于根尖周炎患牙根管内消毒的疗效优于甲醛甲酚。     

常用根管消毒药物对犬牙根管内优势致病菌消毒作用研究

目的:对比研究碘仿糊剂、FC、Vitapex和氢氧化钙糊剂4种根管消毒药物对犬牙根管内根尖周病优势致病菌的抗菌活性。方法:健康成年杂种犬4只,随机选取单根管前牙,建立犬牙根尖周病模型。取根管预备前后根管内细菌进行培养和计数,将碘仿糊剂、FC、Vitapex、氢氧化钙糊剂分别封入4组根管内,对照组封无菌纸捻,7 d后再取样进行细菌培养和计数,对细菌计数结果进行统计学分析。结果:①根管预备后的各种细菌数量均较根管预备前明显减少,差异有统计学意义(P<0.05);②封药后根管内细菌数量大部分为0,但4种消毒药物抗菌活性比较无显著统计学意义(P>0.05)。结论:完善的根管预备能有效去除大部分根管内优势致病菌,4种消毒药物对犬牙根管内的优势致病菌均有抗菌作用。     

Effect of different root canal sealers on periapical repair of teeth with chronic periradicular periodontitis

Teeth with induced chronic periradicular periodontitis in dogs were root canal treated. After the biomechanical preparation, using K files and 5.25% sodium hypochlorite as the irrigant solution, all root canals were dressed with an antibacterial dressing based on calcium hydroxide, which was left in place for 7 days. After this time, the root canals were obturated with lateral condensation of cold gutta-percha with either a calcium hydroxide root canal filling material (Sealapex) or a zinc oxide-eugenol sealer (Fill Canal). After 270 days, histopathological analysis showed better apical and periapical repair in the teeth obturated with Sealapex ( P < 0.05).     

氯化镧对根管内粪肠球菌抗菌效果的体外实验

目的:研究氯化镧、FC、CP、氢氧化钙丙二醇糊剂4种根管消毒剂对离体牙根管内粪肠球菌的抗菌性能。方法:选取72个新鲜拔除的单根管前磨牙,随机分为4个实验组(氯化镧组、FC组、CP组、氢氧化钙丙二醇糊剂组)、1个阴性对照组和1个阳性对照组,每组12个牙。所有牙清理根管后灭菌,除阴性对照组不感染细菌外,其余各组均建立粪肠球菌感染根管模型。建模后,4个实验组分别在根管内放置氯化镧药液、FC、CP、氢氧化钙丙二醇糊剂;阴性和阳性对照组放置生理盐水,37℃、50 mL/L CO2培养箱内培养。分别于培养后3 d和7 d时,取各组根管内壁牙本质粉末用BHI培养基继续培养72 h,比浊仪检测各样本的浊度。结果:①药物处理第3天时,氯化镧组牙本质小管中残留菌量较阳性对照组少,但高于阴性对照组和FC组、氢氧化钙丙二醇糊剂组(P<0.05),与CP组无显著性差异(P>0.05);②药物处理第7天时,FC组、CP组、氢氧化钙丙二醇糊剂组和氯化镧组4种消毒剂牙本质小管内残留细菌量较阳性对照组有明显减少(P<0.05),与阴性对照组相比,差异均无统计学意义(P>0.05)。结论:根管内放置氯化镧药液7 d可有效抑制粪肠球菌生长。     

Effect of endodontic procedures on enterococci, enteric bacteria and yeasts in primary endodontic infections

AIM: To detect enterococci, enteric bacteria and yeast species from the canals of teeth with primary endodontic infections before and after canal preparation and to test the antibiotic susceptibility of enterococcal strains isolated from infected root canals. METHODOLOGY: Twenty-five single-rooted teeth with pulp necrosis, intact pulp chambers and periradicular lesions were selected for study. Samples were collected from canals before and after instrumentation. Amongst isolated microorganisms from infected root canals only enterococci, enteric bacteria and yeasts were identified by biochemical tests. The in vitro antimicrobial susceptibility of isolated enterococci strains was evaluated by the Etest system. RESULTS: Microorganisms were isolated from 92% of the samples following intracoronal access, 22% were enterococci, enteric bacteria or yeast species. After biomechanical preparation, these species were no longer detected. After 7 days without intracanal dressing, 100% of the canals contained microorganisms, 52% of which were target species. However, after using paramonochlorophenol [PRP (2.0 g), Rinosoro and polyethylene glycol (400 equal parts up to 100 mL)] as an intracanal dressing for 7 days, enteric bacteria and yeasts were not detected; only enterococci were still present. All strains of enterococci were susceptible to ampicillin, but exhibited variable susceptibility to rifampin and ciprofloxacin. CONCLUSIONS: Enterococci, enteric bacteria and yeasts were present in primary endodontic infections. Enterococci, particularly Enterococcus faecalis and E. faecium were resistant to removal by root canal preparation followed by intracanal dressing.     

Differences in the confluence of mesial canals in mandibular molar teeth with three or four root canals

Aim  To investigate the correlation between number of root canals and their confluence in mandibular molar teeth.
Methodology  A total of 553 first and 383 second mandibular molars were root filled between the beginning of 1997 and the end of 2006. Access cavities were prepared and the pulp chamber floors were carefully inspected with an endodontic explorer under magnification of 4×. After negotiating the root canal system, the 'straightest' canal of each root was instrumented. A gutta-percha cone was placed in the canal and a small file (08 or 10) was inserted to working length and then removed in all other canals. The gutta-percha cone was removed and inspected for notches indicating the presence of confluences. If it was not possible to probe completely one or more canals, the canal confluences were classified as 'not determined' (ND) if there was no sign of confluence; if a notch was present canals were considered confluent. For each tooth, the number of root canals and the presence of confluences were recorded. To test whether there was a difference in frequency of confluences between teeth with three and four root canals the chi-squared analysis with Yates' continuity correction was performed.
Results  The frequency of a confluence in mesial canals of first molars was 56% in teeth with three root canals and 34% in teeth with four canals. In second molars, it was 67 and 41%, respectively. Differences in the frequency of confluences in teeth with three and four root canals were statistically significant both in first and in second molars.
Conclusions  A greater incidence of confluent canals occurred in teeth with three rather than with four root canals both in first and second mandibular molars.     

Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis

This study investigated the role of infection on the prognosis of endodontic therapy by following-up teeth that had had their canals cleaned and obturated during a single appointment. The root canals of 55 single-rooted teeth with apical periodontitis were thoroughly instrumented and irrigated with sodium hypochlorite solution. Using advanced anaerobic bacteriological techniques, post-instrumentation samples were taken and the teeth were then root-filled during the same appointment. All teeth were initially infected; after instrumentation low numbers of bacteria were detected in 22 of 55 root canals. Periapical healing was followed-up for 5 years. Complete periapical healing occurred in 94% of cases that yielded a negative culture. Where the samples were positive prior to root filling, the success rate of treatment was just 68%— a statistically significant difference. Further investigation of three failures revealed the presence of Actinomyces species in each case; no other specific bacteria were implicated in failure cases. These findings emphasize the importance of completely eliminating bacteria from the root canal system before obturation. This objective cannot be reliably achieved in a one-visit treatment because it is not possible to eradicate all infection from the root canal without the support of an inter-appointment antimicrobial dressing.     

Nd:YAG激光和Er:YAG激光对根管内粪肠球菌杀灭效果的研究

［摘要］ 目的 观察Nd:YAG激光、Er:YAG激光及两者联用对根管内粪肠球菌的杀灭效果。方法 选取离体牙建立粪肠球菌感染模型,随机分为五组：A组：生理盐水组;B组：1%次氯酸钠溶液组;C组：Nd:YAG激光组;D组：Er:YAG激光组;E组：Nd:YAG激光+Er:YAG激光组。通过细菌培养和扫描电镜观察对比各组的杀菌效果。结果 细菌培养和扫描电镜结果显示：A组杀菌率最低,B组杀菌率最高,E组次高。除C组和D组间杀菌率相近外（P>0.05）,各组间均有统计学差异（P<0.05）。结论 Nd:YAG激光和Er:YAG激光均有一定的根管杀菌效果,两者联用效果更佳,可作为传统消毒方法的补充。