Histobacteriologic Conditions of the Apical Root Canal System and Periapical Tissues in Teeth Associated with Sinus Tracts

Introduction

This histobacteriologic study described the pattern of intraradicular and extraradicular infections in teeth with sinus tracts and chronic apical abscesses.

Endodontically treated teeth and periapical findings in the elderly

The radiographic quality of root-canal fillings, the prevalence of periapical findings and their associations with gender and age and were investigated in 133 dentate old people living at home (45 males and 88 females, aged 76, 81, and 86 years and who had endodontically treated teeth or periapical lesions. Sixteen per cent of the endodontically treated teeth (n= 507) exhibited periapical lesions, compared with 4% for the teeth not endodontically treated (P < 0.0001) (χ² test). Lesions were least prevalent in association with radiographically adequate root canal fillings (10%), and most prevalent in teeth with root canal post perforation (100%). Overfilled root canals and multi-rooted teeth with one or more unfilled roots also showed a high percentage of lesions (19% and 22%, respectively). Men had more periapical lesions than women in endodontically treated teeth (P < 0.0001, Mann-Whitney U-test), a finding contrary to previous studies in younger subjects. There were no other statistically significant differences between the sexes or age groups, although the percentage of root-filled teeth increased with age.     

Transmission of Periodontopathic Bacteria from Natural Teeth to Implants

Purpose: Prevention of peri‐implantitis is essential for the success of implant rehabilitation. Infection by periodontopathic bacteria is a major cause of peri‐implantitis. The aim of the present study was to identify the source of peri‐implant colonization by periodontopathic bacteria. Materials and Methods: Twenty‐one patients with implants were enrolled in the study. Subgingival plaque samples from the adjacent, occluding, and contralateral natural teeth were collected prior to second‐stage surgery. Samples from implant sulci were then obtained 2 weeks later. Detection of periodontopathic bacteria was performed by the polymerase chain reaction. Results: The detection rates for Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Fusobacterium nucleatum in all subgingival samples from natural teeth were similar to that in the peri‐implant sulci. Multiple logistic regression analysis revealed an association between the detection of A. actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, and F. nucleatum in the gingival crevices of adjacent teeth and that of the peri‐implant sulcus, but no association for Tannerella forsythia. Conclusions: The present findings suggest that colonization by A. actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, and F. nucleatum at the implant sulcus was affected by these microorganisms in the gingival crevice of adjacent teeth rather than those on occluding and contralateral teeth.     

Microbiological evaluation of primary endodontic infections in teeth with and without sinus tract

Aim To examine the microbiological status of primary endodontic infections in teeth with and without a sinus tract. Methodology Samples were collected by means of a size 15 H‐type file and two sterile paper points from 30 cases of primary endodontic infections with (n = 15) or without (n = 15) a sinus tract. The presence of 40 bacterial species was determined by the checkerboard DNA‐DNA hybridization method. Results The species found at the highest levels and prevalence were Fusobacterium nucleatum sp. vincentii, Porphyromonas gingivalis, Veillonella parvula, Enterococcus faecalis, Campylobacter gracilis and Neisseria mucosa. Total bacterial counts were similar between teeth with (44 × 10⁵) and without (50 × 10⁵) a sinus tract (t‐test: P > 0.05). E. faecalis, Streptococcus anginosus, Capnocytophaga sputigena and Capnocytophaga gingivalis had significantly higher counts in the absence of sinus tract (Mann–Whitney test, P < 0.05). Higher levels of P. gingivalis and Fusobacterium nucleatum sp. nucleatum were observed in cases with a sinus tract. Leptotrichia buccalis (OR = 1.83; CI 95%) and Porphyromonas endodontalis (OR = 2.15; CI 95%) were associated with an increased chance of subjects having a sinus tract. Conclusions Primary endodontic infections were associated with a large variety of bacterial species. Specific differences between the composition of the microbiota of primary root canal infections were observed in cases with or without a sinus tract.     

Conservative treatment of patients with periapical lesions associated with extraoral sinus tracts

This paper describes the clinical courses of three cases with extra-oral sinus tract formation, from diagnosis and treatment to short-term follow-up and evaluation. All teeth involved had periradicular radiolucent areas noted on radiographic examination and extra-oral sinus tracts appearing on the chin with exudation and unpleasant aesthetic appearance. The adopted treatment protocol included treating the sinus tract surface simultaneously with the root canal therapy. After root canal shaping using 5.25% sodium hypochlorite solution, calcium hydroxide-based pastes associated with different vehicles were inserted into the root canal for 4 months, and were changed monthly. All the sinus tracts healed in 7 to 10 days. The apical lesions were completely repaired in a maximum period of 24 months. The treatment adopted provided a complete healing of the periapical lesions in a short follow-up period. Surgical repair of the cutaneous sinus tract was therefore unnecessary.     

Resolution of Nasal Sinus Tract after Endodontic Therapy: A Case Report with Microbial Analysis

This case report describes the resolution of a 20-year misdiagnosed nasal sinus tract after root canal therapy with multiple sessions of calcium hydroxide (Ca[OH]₂) intracanal medication. Clinical evaluation, including diagnostic testing and sinus tract tracing, was performed followed by a cone-beam computed tomographic scan and 3-dimensional reconstruction of the apical lesion. Bacteria and endotoxin analyses were performed from the nasal sinus tract and paired root canal infection before (s1) and after instrumentation (s2) and after 7 (s3), 14 (s4), and 21 (s5) days of Ca(OH)₂ medication. The bacteria analysis was performed using the checkerboard DNA-DNA hybridization method and endotoxin quantified by the limulus amebocyte lysate method. A similar microbiota profile was found in the sinus tract and paired root canal infection. No target bacterial species were detected in the root canal at s2, s3, and s5. In contrast, Actinomyces israellii and Eubacterium nodatum were detected at s4. Differences in bacterial detection were found between s1 × s2, s3 × s4, and s4 × s5 (all P < .05). Endotoxin was detected in the root canal at all sampling times. Differences in the levels of endotoxin were found between s1 × s2, s2 × s3, and s3 × s4 (all P < .05).The bacterial analysis revealed similar microbiota profiles present in the nasal sinus tract and paired root canal infection with the participation of a wide variety of gram-positive and -negative species. Additionally, root canal therapy with multiple sessions of Ca(OH)₂ intracanal medication for 21 days was effective in disinfecting the root canal system and resolving the nasal sinus tract.     

Bacteremia in conjunction with endodontic therapy

Abstract This study characterizes oral microorganisms believed to have spread from the root canal into the blood stream during and after endodontic therapy of teeth with Asymptomatic apical periodontitis. Microbiological samples were taken under aseptic conditions from the root canal of 26 single-rooted teeth in 26 patients. In the endodontic treatment of 13 of the patients (Group 1), the first 3 reamers, sizes 15, 20 and 25, were used to a level 2 mm beyond the apical foramen. In the other 13 patients (Group 2), the instrumentation ended inside the root canal 1 mm short of the apical foramen. Blood samples were taken from the patients during the instrumentation and 10 min after the treatment was completed. Anaerobic microorganisms were isolated from all root canals. In 7 patients of Group 1, Propionibacterium acnes, Peptostreptococcus prevotii, Fusobacterium nucleatum, Prevotella intermedia and Saccharomyces cerevisiae were recovered from the blood. In 4 patients of Group 2, P. intermedia, Actinomyces israelii, Streptococcus intermedius and Streptococcus sanguis were isolated from the blood. Biochemical tests and antibiograms revealed that the isolates from the root canal and blood had identical profiles within the patients, strongly suggesting that the microorganisms isolated from the blood had the root canal as their source.     

Alkali‐resistant bacteria in root canal systems

The aim of this study was to isolate and identify alkali‐resistant bacteria from the dentin of infected root canals. Bacteria from homogenized dentin powder made up from infected root canal walls from human teeth were cultured on buffer‐enriched Brain Heart Infusion agar supplemented with 4% sheep blood (BHI‐blood agar), adjusted to pH 7.0, 9.0 or 10.0. Incubation took place for 7 days at 37°C in an anaerobic glove box. Bacterial strains selected according to colony and morphology were subcultured in buffer‐enriched BHI broth adjusted to pH 9.0, 10.0 or 11.0 to confirm their growth as alkali‐resistant bacteria. Polymerase chain reaction amplification using specific primer sets and 16S rDNA sequence analysis was performed for identification of alkali‐resistant isolates. In the present study, 37 teeth extracted from 37 patients were used for preparation of the dentin powder samples. Bacteria were detected in 25 samples when standard BHI‐blood agars (pH 7.0) were used. Of these, 29 strains from 15 samples were alkali resistant, 25 strains growing at pH 9.0 and 4 at pH 10.0. The alkali‐resistant strains included Enterococcus faecium (10 strains) and Enterococcus faecalis (2 strains), Enterobacter cancerogenus (1 strains), Fusobacterium nucleatum (1 strains), Klebsiella ornithinolytica (2 strains), Lactobacillus rhamnosus (2 strains), Streptococcus anginosus (2 strains), Streptococcus constellatus (3 strains), and Streptococcus mitis (2 strains). Three strains were also identified as bacteria of genus Firmicutes or Staphylococcus at the genus level. The present study showed that many bacterial species in infected root canal dentin were alkali‐resistant at pH 9.0 and/or pH 10.0, and belonged mainly to the genus Enterococcus.     

“True” Versus “Bay” Apical Cysts: Clinical,Radiographic, Histopathologic,and Histobacteriologic Features

IntroductionThis study compared the main clinical, radiographic, and histologic features of true and bay apical cysts.MethodsThe study material comprised 95 biopsy specimens of apical periodontitis lesions obtained attached to the root tip of both untreated and root canal–treated teeth. Clinical and radiographic data were recorded. Specimens were obtained by extraction or periradicular surgery and were meticulously processed for histopathologic and histobacteriologic methods. All cases diagnosed as apical cysts (n = 23) were divided into the true and bay types, which were then compared for tooth location, patient’s sex, lesion size, severity of clinical symptoms, presence of a sinus tract, previous abscess episodes, and prevalence of bacteria in the main root canal lumen and ramifications, on the outer root surface, and within the cyst cavity.ResultsEleven specimens were classified as true (48%) and 12 (52%) as bay cysts. Bacteria were found in all specimens, regardless of the histopathologic diagnosis. Planktonic bacteria were observed in the main root canal in all true cysts and in 11 of 12 (92%) bay cyst cases. Biofilms were detected in the main canal in 10 cases from each diagnostic group and were frequently observed in ramifications. Extraradicular biofilms occurred in a few specimens only. Bacteria were visualized within the cavity of both true (4/11, 36%) and bay (6/12, 50%) cyst specimens. The severity of histologic inflammation was always high. There were no significant differences between true and bay cysts for all the clinical, radiographic, histopathologic, and histobacteriologic parameters assessed.ConclusionsExcept for the morphologic relationship of the cyst cavity with the root canal space, true and bay cysts exhibited no other significant differences in the various parameters evaluated. The 2 cyst types were always associated with an intraradicular infection and sometimes with an extraradicular infection. Findings question the need to differentiate true and bay cysts and do not support the assumption that true cysts are self-sustainable entities not maintained by infection.     

Direct amplification of rRNA gene sequences for identification of selected oral pathogens in root canal infections

Aim The purpose of this study was to assess the prevalence of selected oral pathogens in root canal infections and their relationship with symptoms using a highly sensitive technique, the polymerase chain reaction. Methodology Samples were obtained from 91 infected teeth associated with periradicular lesions, including cases of acute periradicular abscesses. DNA was extracted from the samples and analysed for the presence of target microbial species using a PCR‐based identification assay. Results All samples were positive for the presence of bacteria. Streptococcus anginosus group was detected in 16.7%, Fusobacterium nucleatum in 14.3%, and Bacteroides forsythus in 7.1% of the abscess samples. No pus sample yielded Actinomyces israelii, Actinobacillus actinomycetemcomitans or fungal species. In general, B. forsythus was found in 20% of the cases (16 of 80), S. anginosus in 12% (6 of 50), F. nucleatum in 10% (6 of 60) and A. israelii in 5% (two of 40). A. actinomycetemcomitans was not detected in any case. Fungi were present in only one of 50 cases (2%). There was no correlation between the species and symptoms. Conclusions Direct molecular approaches appear to be a valuable tool for the rapid and reliable diagnosis of infectious diseases, as well as for research purposes. There was no correlation between target microbial species and symptoms.     

Bacteria recovered from teeth with apical periodontitis after antimicrobial endodontic treatment

Chávez de Paz LE, Dahlén G, Molander A, Möller Å, Bergenholtz G . Bacteria recovered from teeth with apical periodontitis after antimicrobial endodontic treatment. International Endodontic Journal, 36 , 500–508, 2003. Aim To determine whether there is a pattern for certain bacteria to remain after chemo‐mechanical treatment of root canals in teeth with apical periodontitis. Methodology Consecutive root‐canal samples of 200 teeth receiving root‐canal treatment, referred from general practitioners and endodontic specialists for analyses of cultivable microbes, were studied prospectively. To be included, samples had to be taken at a treatment session subsequent to the one at which endodontic therapy was initiated. All samples were from teeth that either presented with clinical or radiographic evidence of apical periodontitis or both. Bacteriological findings were linked to clinical and radiographic parameters including status of the root canal prior to treatment, namely, vital pulp, necrotic pulp or root filled. Results A total of 248 strains were isolated from 107 teeth giving bacterial growth. Gram‐positives predominated (85%). Lactobacillus spp. (22%), nonmutans streptococci (18%), and Enterococcus spp. (12%) were the most common isolates. Gram‐negative anaerobes were relatively sporadic. Large radiographic bone lesions, persistent pain and use of intracanal calcium hydroxide dressing correlated with bacterial presence (P < 0.05). Conclusions Once established, nonmutans streptococci, enterococci and lactobacilli appear to survive commonly following root‐canal treatment of teeth with clinical and radiographical signs of apical periodontitis.     

The role of Toll‐like receptors 2 and 4 on reactive oxygen species and nitric oxide production by macrophage cells stimulated with root canal pathogens

Introduction: Periapical lesions arise as a result of the activation and interaction of the host immune responses against root canal infection. Recently identified Toll‐like receptors (TLR) seem to be involved in the recognition and development of immune responses against a myriad of microorganisms. However, very little information is available on the role of TLR in the induction of periapical lesions. Method: The role of TLR‐2 and TLR‐4 in the activation of murine macrophages stimulated using Fusobacterium nucleatum and Peptostreptococcus anaerobius was investigated. The production of nitric oxide (NO) and reactive oxygen species (ROS) was assessed. Results: The results demonstrate that TLR‐2 and TLR‐4 are involved in the production of ROS by activated macrophages. The microorganisms induced similar levels of NO production by TLR‐2‐competent and TLR‐2‐deficient macrophages, regardless of the addition of interferon‐γ (IFN‐γ), ruling out a role for TLR‐2 in the NO production induced by these bacteria. Only P. anaerobius induced NO production by TLR‐4‐competent macrophages without the addition of IFN‐γ. However, after IFN‐γ addition, F. nucleatum induced macrophage NO production. Therefore, NO production stimulated by IFN‐γ and these microorganisms seems to be TLR‐4‐independent. Conclusion: TLR‐2 seems to be involved in the induction of ROS production by macrophages in response to prevalent root canal bacteria, while only F. nucleatum induced ROS production by TLR‐4‐competent macrophages. Both microorganisms significantly induced large amounts of NO independent of TLR‐2 and TLR‐4. We conclude that microorganisms may participate in the induction and progression of periapical lesions through NO and ROS production by activated macrophages.     

The Dynamics of Periapical Lesions in Endodontically Treated Teeth That Are Left without Intervention: A Longitudinal Study

Introduction

The long-term dynamics of periapical lesions in endodontically treated teeth is not fully elucidated, thus presenting a clinical dilemma regarding the need for an intervention. The aim of the study was to retrospectively evaluate the long-term dynamics of periapical lesions that were left without intervention in endodontically treated teeth.

Methods

Periapical status surveys of patients treated in a public dental clinic were retrospectively evaluated for the presence of periapical lesions in endodontically treated coronally restored teeth. The dynamics of the included periapical lesions was evaluated based on the periapical index (PAI) score changes between 2 consecutive periapical surveys of at least a 4-year interval. The influence of various factors on lesion dynamics was statistically evaluated.

Results

The study cohort consisted of 74 patients with a total of 200 endodontically treated teeth having periapical lesions that fulfilled the inclusion criteria. Fifty-seven (28.5%) lesions remained unchanged, 103 (51.5%) lesions worsened (PAI score increased), and 40 (20%) lesions improved (PAI score decreased). Poor root canal filling and poor restoration were found to adversely affect the long-term dynamics of the periapical lesions (P < .05). Age, sex, and the presence of a post had no statistically significant influence on lesion dynamics (P > .05).

Conclusions

Poor root canal filling and poor restoration may adversely affect the long-term dynamics of periapical lesions that are left without intervention in endodontically treated teeth. Therefore, in cases of poor root canal filling or poor restoration, further intervention may be indicated.     

Influence of residual bacteria on periapical tissue healing after chemomechanical treatment and root filling of experimentally infected monkey teeth

The purpose of this study was twofold: first, to determine the influence on the healing of the periapical tissues when selected bacterial strains and combinations thereof remain after root canal treatment; and, second, the relationship to healing of the quality of the root filling. In eight monkeys, 175 root canals, previously infected with combinations of four or five bacterial strains and with radiographically verified apical periodontitis, were endodontically treated, bacteriologically controlled, and permanently obturated. After 2-2.5 yr, the periapical regions were radiographically and histologically examined. Of these teeth, 48 root canals were also examined for bacteria remaining after removal of the root fillings. When bacteria remained after the endodontic treatment, 79% of the root canals showed non-healed periapical lesions, compared with 28% where no bacteria were found. Combinations of residual bacterial species were more frequently related to non-healed lesions than were single strains. When no bacteria remained, healing occurred independently of the quality of the root filling. In contrast, when bacteria remained, there was a greater correlation with non-healing in poor-quality root fillings than in technically well-performed fillings. In root canals where bacteria were found after removal of the root filling, 97% had not healed, compared with 18% for those root canals with no bacteria detected. The present study demonstrates the importance of obtaining a bacteria-free root canal system before permanent root filling in order to achieve optimal healing conditions for the periapical tissues.     

Microbial flora of root canal–treated teeth associated with asymptomatic periapical radiolucent lesions

This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty‐four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re‐treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37°C in both a carbon dioxide‐enriched atmosphere and anaerobically. Eighteen teeth that had received gutta‐percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3×10⁵. The number of bacterial genera recovered ranged between 0 and 6, with facultative gram‐positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase‐negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.     

Association between Endodontically Treated Maxillary and Mandibular Molars with Fused Roots and Periapical Lesions: A Cone-beam Computed Tomography Cross-sectional Study

IntroductionFused root variations of the root canal system increase the complexity of the inner root canal system anatomy. The aim of the present study was to determine, in in vivo conditions, the proportion of periapical lesions in association with endodontically treated maxillary and mandibular molars with fused roots presenting previous root canal treatment by assessing preexisting data via cone-beam computed tomographic volumes.MethodsA total of 1160 CBCT scans with an overall sample of 20,836 teeth were screened. A global count of 3701 maxillary molars and mandibular second molars were included in the study. The Cohen kappa test and interclass correlation coefficient tested the intra- and interrater reliability, respectively. The percentage of periapical lesions associated with molars with or without root fusion was determined. Proportions were expressed with 95% confidence intervals (CIs). The z test for proportions was used to analyze differences between subgroups, and an odds ratio was calculated in order to understand the association between periapical lesions and root configuration.ResultsFused molars presented a prevalence of periapical lesions in endodontically treated teeth of 74.0% (95% CI, 65.2%–82.8%), whereas nonfused molars had a proportion of periapical lesions in root canal–treated teeth of 69.5% (95% CI, 65.2%–73.8%; P > .05). Endodontically treated molars with fused roots presented with 1.3 higher odds of being associated with periapical lesions than endodontically treated molars with nonfused roots.ConclusionsA tendency of a higher proportion of periapical lesions was found in the fused rooted molars with a history of root canal treatment when compared with nonfused teeth; however, no statistically significant difference was noted.     

Endodontic re‐treatment associated with the elimination of amalgam root‐end filling through sinus tracts: A report of two cases

Two patients presented with complaints of recurrent drainage of purulent exudate from sinus tracts, inflammation and pain after endodontic re‐treatment of the maxillary left (Case 1) and right (Case 2) lateral incisors. The periapical lesions persisted after apical curettage, apicectomy and root‐end filling with silver amalgam. Radiographic examination exposed the poor quality of the endodontic treatments and the silver amalgam root‐end fillings, which were associated with periapical radiolucent areas in both teeth. The sinus tract persisted after root canal cleaning and shaping, followed by a calcium hydroxide root canal dressing. The root‐end fillings were periapically dislodged with endodontic K‐files, and showed progressive displacement by sinus tracts up to elimination in the oral cavity. Follow ups of 42 and 65 months post procedure revealed clinical disappearance of the symptoms, sinus tracts and exudates, and radiographs revealed that the repair process of the periapical radiolucent areas was quite advanced.     

Healing of periapical lesions of pulpless teeth after endodontic treatment with controlled asepsis

Abstract Using a careful anaerobic bacteriological technique, bacteria were shown to be eliminated from infected root canals before the endodontic treatment was finished by root filling. Healing of the periapical lesions of the teeth was followed for 2–5 yr. The majority of the 79 lesions healed completely or decreased in size in such a way that they could be expected to heal. In 5 cases there was no or only an insignificant decrease in the size of the lesions. Two of these lesions were shown to contain bacteria of the species Actinomyces or Arachnid. In another case there were dentin chips in the periapical tissue. Periapical lesions which fail to heal in spite of careful bacteriological monitoring of the endodontic treatment may in some cases be due to an establishment of the bacteria outside the root canal in the periapical tissue. In these sites, the bacteria are inaccessible to conventional endodontic treatment.     

New Bacterial Compositions in Root-filled Teeth with Periradicular Lesions

The aim of this study was to isolate and detect microorganisms of root-filled teeth associated with periradicular lesions. Specimens were sampled from patients undergoing root canal retreatment. The bacteria were characterized by morphologic and biochemical analysis and by 16S rRNA gene sequencing. Microorganisms were detected in 10 of 18 teeth. The majority of positive samples revealed a mixed culture of 2–8 species. In 2 teeth Enterococcus faecalis was the only detected species. For the first time Vagococcus fluvialis was detected in root canals. Solobacterium moorei and Fusobacterium nucleatum were the most prevalent species. Presence of F. nucleatum was associated with the presence of S. moorei in 5 of 7 cases. In all teeth with Parvimonas micra and Dialister invisus, F. nucleatum and S. moorei were found. Moreover, members of additional different genera were detected delivering bacterial compositions that have been not described yet.     

The Influence of Missed Canals on the Prevalence of Periapical Lesions in Endodontically Treated Teeth: A Cross-sectional Study

IntroductionUntreated root canals may have a direct impact on the prognosis of root canal treatment. The objective of this cross-sectional study was to evaluate the association of missed canals with periapical lesions in endodontically treated teeth.MethodsOne thousand one hundred sixty preexisting cone-beam computed tomographic scans from 8 different health centers were assessed between January 2018 and December 2018 by 5 independently calibrated observers. Two thousand three hundred five endodontically treated teeth were identified in a sample of 20,836 teeth (27,046 roots). All endodontically treated teeth were evaluated for the presence or absence of missed root canals and periapical lesions. The z test for proportions was used to analyze differences between groups, and an odds ratio was calculated in order to analyze the association between missed canals and lesions. P < .05 was considered statistically significant.ResultsThe prevalence of missed canals was 12.0%, and teeth with untreated canals were associated with periapical pathology in 82.6% of the cases. The root presenting with the highest percentage of missed canals (62.8%) was the mesiobuccal root of the maxillary first molar, being associated with periapical lesions in 75.2% of cases. Maxillary molar mesiobuccal roots presenting with a missed canal were 3.1 times more likely to be associated with periapical pathology than maxillary molars with all canals identified and treated.ConclusionsThe association between untreated root canals and the presence of periapical lesions noted in the present study shows that missed canals have a significant impact on treatment prognosis.