Molecular Analysis of the Antibacterial Effects of Photodynamic Therapy in Endodontic Surgery: A Case Series.

In this case series, bacterial reduction promoted by antimicrobial photodynamic therapy (PDT) used during endodontic surgery was evaluated. Cases were also followed up, and the surgical outcome was reported. The study consisted of 19 teeth with posttreatment apical periodontitis that were consecutively treated by endodontic surgery. After apicoectomy, the root end was treated with PDT using methylene blue as the photosensitizer. Bacteriologic samples were taken from both the cut root surface and the root-end cavity before and after PDT. Samples were analyzed for the total bacterial and Streptococcus group counts using quantitative real-time polymerase chain reaction. EndoSequence BC-RRM Putty (Brasseler, Savannah, GA) was used as the root-end filling. Patients were followed up, and the surgical outcome was evaluated. The reduction in bacterial counts after the PDT approach was analyzed using the nonparametric Wilcoxon signed rank test. PDT significantly reduced the total bacterial and streptococcal counts in both root-end cavities and resected root surfaces (P < .05). The success rate for 15 teeth that were available for recall after 12 to 21 months was 93% under a loose evaluation criterion and 73% under a rigid one. Used during endodontic surgery, PDT significantly enhanced disinfection of the cut surface area and root-end cavity. Cases treated with PDT showed a high healing rate.

Management and Histobacteriological Findings of Mucosal Fenestration: A Report of 2 Cases.

This article describes 2 unusual cases of mucosal fenestration associated with necrotic infected teeth, resulting in exposure of the root apex to the oral cavity. Both cases consisted of maxillary incisors with pulp necrosis and radiographic/tomographic evidence of apical periodontitis. Clinically, the root apex was exposed to the oral cavity through a fenestration in both bone and mucosa and covered with bacterial plaque and calculus. These teeth were treated by a combination of nonsurgical and surgical endodontic treatment. During surgery, the root apices were resected to within the alveolus and the fenestrated area covered by the flap. Specimens consisting of the root apex and surrounding soft tissues were subjected to histopathological and histobacteriological analyses. Histobacteriological analysis revealed extensive resorptive defects on the root apices filled with thick bacterial biofilm, irregular detachment of the cementum layers with consequent infection of the underlying spaces, and heavy infection in the apical foramina. The soft tissue specimens exhibited no or minimal inflammation. The 2 cases showed satisfactory postsurgical healing of the hard and soft tissues. Both cases of mucosal fenestration showed root apices covered with dense bacterial biofilms and associated with a bone crypt with no significant inflammatory tissue therein. The 2 cases were successfully treated by conservative approaches involving a combination of nonsurgical and surgical endodontic treatment with root-end resection.

Molecular Typing of Enterococcus faecalis from Persistent Endodontic Infections / Tipificación Molecular de Enterococcus faecalis Provenientes de Infecciones Endodónticas Persistentes

ABSTRACT: Molecular techniques that provide valuable information about the epidemiology of oral strains. The purpose of this study was to determine the genetic relatedness of 83 Enterococcus faecalis strains isolated from treated root canals. These strains were obtained from patients who were treated for persistent endodontic infections. E. faecalis isolates were molecular typed by Pulsed Field Gel Electrophoresis using Smal. Ten clonal groups and 13 pulse types with 38.7 % similarity for the less related strains were identified. Genetic heterogeneity among strains from different patients and a high level of genetic homogeneity among intrapatient strains were observed. Therefore, restriction endonuclease fingerprinting of genomic DNA from E. faecalis strains confirmed the polyclonality of the isolates obtained from the root canals of patients diagnosed with persistent endodontic infections, compared with other reports. These results provide additional data for a better understanding of the epidemiological aspects of root canal infections by E. faecalis.

RESUMEN: Las técnicas moleculares proporcionan información valiosa sobre la epidemiología de aislados orales. El propósito de este estudio fue determinar la relación genética de 83 cepas de Enterococcus faecalis aisladas de conductos radiculares tratados. Estas cepas se obtuvieron de pacientes que fueron tratados por infecciones endodónticas persistentes. Los aislados de E. faecalis se tipificaron molecularmente por electroforesis en gel de campo pulsado usando Smal. Se identificaron diez grupos clonales y 13 pulsotipos con un 38,7 % de similitud para las cepas menos relacionadas. Se observó heterogeneidad genética entre las cepas de diferentes pacientes y un alto nivel de homogeneidad genética entre las cepas intrapacientes. Por lo tanto, la toma de huellas dactilares a traves de restricción de ADN genómico de cepas de E. faecalis confirmó la policlonalidad de los aislados obtenidos de los conductos radiculares de pacientes diagnosticados con infecciones endodónticas persistentes, en comparación con otros informes. Estos resultados proporcionan datos adicionales para una mejor comprensión de los aspectos epidemiológicos de las infecciones del conducto radicular por E. faecalis.

Association between bacteria occurring in the apical canal system and expression of bone-resorbing mediators and matrix metalloproteinases in apical periodontitis.

AIM: To evaluate the association between the presence of selected bacterial species/groups in the apical root canal and expression of mediators of soft and bone tissue destruction in apical periodontitis lesions. Relationships between bacteria and some other features of apical periodontitis were also investigated. METHODOLOGY: Seventeen freshly extracted teeth with pulp necrosis and apical periodontitis were included. The apical root segment was sectioned and cryopulverized; DNA was extracted and evaluated for the presence of 9 bacterial species/groups using real-time polymerase chain reaction. Lesions were processed for histopathological and immunohistochemical analyses, which targeted matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9), receptor activator of NFκB (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG). Associations of the target bacteria with expression of these mediators, presence of symptoms, lesion size and histopathological diagnosis were evaluated. Data were analysed using the chi-square, Fisher's exact, Mann-Whitney and Pearson tests. P values lower than 0.05 were considered significant. RESULTS: All pulverized apical root samples were positive for bacteria. The most prevalent taxa were Actinobacteria (53%), Streptococcus species (35%), Fusobacterium species and Parvimonas micra (18%). The target mediators exhibited a high mean expression in the lesions (MMP-2: 82%; MMP-9: 73%; RANK: 78%; RANKL; 81%; OPG; 83%). Mean RANKL:OPG ratio was significantly higher in granulomas than cysts (P < 0.05, Mann-Whitney test). Actinobacteria were associated with granulomas, higher MMP-2 expression, lower OPG expression, and higher RANKL:OPG ratio (P < 0.05 for all, Fisher's exact test or Mann-Whitney test). No other significant associations were found. CONCLUSION: Actinobacteria may play an important role in the active phase of soft and bone tissue destruction in apical periodontitis.

Bacterial colonization in the apical part of extracted human teeth following root-end resection and filling: a confocal laser scanning microscopy study.

OBJECTIVES: The purpose of this study was to evaluate Enterococcus faecalis colonization at the apical part of root canals following root-end resection and filling using confocal laser scanning microscopy (CLSM). MATERIALS AND METHODS: The apical 3-mm root-ends of 55 extracted single rooted human teeth were resected, and 3-mm retrograde cavities were prepared and filled using either mineral trioxide aggregate (MTA), intermediate restorative material (IRM), or Biodentine (n = 10 each); 25 teeth served as controls. The roots were placed in an experimental model, sterilized, and coronally filled with E. faecalis bacterial suspension for 21 days. Then, the apical 3-mm segments were cut to get two slabs (coronal and apical). The slabs were stained using LIVE/DEAD BacLight Bacterial Viability Kit and evaluated using CLSM. RESULTS: The fluorescence-stained areas were larger in the bucco-lingual directions compared with the mesio-distal directions (p < 0.05). The mean and maximal depths of bacterial colonization into the dentinal tubules were 755 and 1643 µm, respectively, with no differences between the root-end filling materials (p > 0.05). However, more live bacteria were found in the MTA group in comparison to IRM and Biodentine groups (p < 0.05). CONCLUSIONS: CLSM can be used to histologically demonstrate bacterial root-end colonization following root-end filling. This colonization at the filling-dentine interfaces and deeper into the dentinal tubules may be inhomogeneous, favoring the bucco-lingual aspects of the root. CLINICAL RELEVANCE: Following root-end resection and filling bacterial colonization may lead to inflammatory reactions at the periapical tissues; the viability of the colonized bacteria may be affected by the type of root-end filling material.

Host-Bacterial Interactions in Post-treatment Apical Periodontitis: A Metaproteome Analysis.

INTRODUCTION: This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis. METHODS: Root apexes and matched inflammatory lesions from root canal-treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap. RESULTS: The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage. CONCLUSIONS: Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.

Extraradicular infection as the cause of persistent symptoms: a case series.

INTRODUCTION: This article describes 3 cases that presented persistent symptoms after appropriate endodontic treatment. Histopathologic and histobacteriologic investigation were conducted for determination of the cause. METHODS: Three cases are reported that presented with persistent symptoms after endodontic retreatment (cases 1 and 2) or treatment (case 3). Periapical surgery was indicated and performed in these cases. The biopsy specimens, consisting of root apices and the apical periodontitis lesions, were subjected to histopathologic and histobacteriologic analyses. RESULTS: Case 1 was an apical cyst with necrotic debris, heavily colonized by ramifying bacteria, in the lumen. No bacteria were found in the apical root canal system. Case 2 was a granuloma displaying numerous bacterial aggregations through the inflammatory tissue. Infection was also present in the dentinal tubules at the apical root canal. Case 3 was a cyst with bacterial colonies floating in its lumen; bacterial biofilms were also seen on the external apical root surface, filling a large lateral canal and other apical ramifications, and between layers of cementum detached from the root surface. No bacteria were detected in the main root canal. CONCLUSIONS: Different forms of extraradicular infection were associated with symptoms in these cases, leading to short-term endodontic failure only solved by periapical surgery.

Evaluation of Apical Contamination in Teeth with Prefabricated Posts Fixed with Different Dental Cements

To assess the sealing capacity of different dental cements regarding apical microleakage on teeth with prefabricated posts. Material and Methods:Forty-eight single-rooted teeth were selectedand, after having their coronal part removed at 10mm standard, underwent endodontic cleaning and preparation. The space for the post was prepared with # 3 Largo bur at 7 mm standard value. The study included the following groups: Group I, post prefabricated with # 1 intracanal glass fiber cemented with zinc phosphate cement (n = 12); Group II, post prefabricated with # 1 intracanal glass fiber cemented with conventional glass ionomer cement, Vidrion C (n = 12); Group III, post prefabricated with # 1 intracanal glass fiber cemented with chemical action resin cement, Multilink (n = 12). Two groups of six teeth each were also included, one as negative control group and the other as positive control. After cementing, teeth were tested through a dual-chamber experimental model, using Enterococcus Faecalis for apical contamination. Results:The control groups behaved as expected: positive control group with total contamination in 11 days and negative control group without any contaminated specimen within observation time of 60 days. Group I showed microleakage in all specimens for up to 29 days (100%)...

Group II and Group III showed microleakage in 50 and 49 specimens (83.33% and 75%) respectively along the research time of 60 days. Group 1 showed microleakage in all specimens for up to 29 days (100%). Group 2 and Group 3 showed microleakage in 50 and 49 specimens (83.33% and 75%) respectively along the research time of 60 days. The Log-Rank test showed differences between Groups 1 and 2 (p<0.05) and between Groups 1and 3 (p<0.05). However, there was no difference between Groups 2 and 3 (p> 0.05). The results showed higher delay in bacterial infiltration in Groups 2 and 3 when compared to Group 1.Conclusion:No cement completely prevented infiltration during the experimental period. Zinc phosphate cement had the lowest apical sealing capacity while glass ionomer cement and resin cement showed similar results...

Effective analysis of the use of peracetic acid after instrumentation of root canals contaminated with Enterococcus faecalis.

INTRODUCTION: The aim of this study was to evaluate the effectiveness of peracetic acid (PAA) in cleaning root canals contaminated with Enterococcus faecalis. METHODS: Sixty first and second mandibular molars were used. Their mesiobuccal canals were prepared with the Reciproc System (VDW, Munich, Germany). The canals were irrigated with 10 mL saline during instrumentation. The teeth were randomly divided into 3 groups (n = 20), according to the irrigation solution to be used after instrumentation: group PAA (5 mL 1% PAA), group EDTA/sodium hypochlorite (NaOCl) (5 mL 17% EDTA followed by 5 mL 2.5% sodium hypochlorite), and group S (5 mL saline). Microbiological samples were collected before instrumentation and after final irrigation. Bacterial quantification was performed by counting the number of colony-forming units (CFUs/mL). The results were analyzed by the nonparametric Wilcoxon and Kruskal-Wallis tests. RESULTS: The 3 groups showed a significant reduction (P < .05) in CFUs/mL after final irrigation. PAA and NaOCl associated with EDTA produced a significantly higher reduction in CFUs/mL (P < .05) compared with saline. There was no statistically significant difference between PAA and EDTA + 2.5% NaOCl (P > .05). CONCLUSIONS: According to the results of the present study, the effectiveness of 1% PAA was similar to that of 17% EDTA + 2.5% NaOCl in cleaning curved root canals contaminated with E. faecalis.

Effect of irrigation with Tetraclean on bacterial leakage of obturated root canals.

The purpose of the study presented here was to evaluate the effect of Tetraclean, Hypoclean, Chlor-XTRA, 2% chlorhexidine and 6% sodium hypochlorite/17% EDTA as a final irrigant on bacterial leakage of the root canal. One hundred and fifty-five extracted human maxillary central incisors were randomly divided into five experimental groups of 25 teeth each and two control groups of 15 teeth each. The root canals in each group were irrigated with 2 ml of the relevant irrigant between each filing. The root canals in group 5 were irrigated with 5 ml of 17% EDTA at the end of root canal preparation. The teeth in each group were obturated with gutta-percha and AH-26 sealer. Positive control teeth were obturated with a single gutta-percha cone without sealer, and negative controls were obturated in the same way as experimental groups. The coronal portion of each root was placed in contact with inoculum of Enterococcus faecalis in Brain Heart Infusion (BHI) culture media. Findings showed that the mean number of days for bacterial penetration in the Tetraclean group was greater than for other experimental groups. On the other hand, the Chlor-XTRA Vista group showed the fewest mean number of days for bacterial leakage.

Infection in a complex network of apical ramifications as the cause of persistent apical periodontitis: a case report.

INTRODUCTION: This article reports a case of persistent apical periodontitis lesion in a mesiobuccal root of a maxillary molar subjected to single-visit endodontic treatment. METHODS: The treatment protocol followed endodontic standards including using nickel-titanium instruments with working length ending 0.5-mm short of the apex, establishment and maintenance of apical foramen patency, irrigation with 5% NaOCl, smear layer removal, a final rinse with and ultrasonic agitation of chlorhexidine, and filling by the vertical compaction technique. Even so, the lesion in the mesiobuccal root became larger in size after follow-up examination at 1 year 6 months, and periradicular surgery was performed. Radiographic control after 11 months showed that periradicular healing was almost complete. The root apex and the lesion were analyzed histologically and histobacteriologically. RESULTS: The lesion was diagnosed as a "pocket cyst," and no bacteria were noted extraradicularly. The cause of continued disease was a heavy bacterial biofilm infection located in an intricate network of apical ramifications. Bacteria were also observed on the walls of one of the mesiobuccal canals packed between the obturation material and the root canal wall. CONCLUSIONS: This case report reinforces the need for treating the infected root canal as a complex system that possesses anatomic intricacies in which bacteria can spread and remain unaffected by treatment procedures.

Endodontic and surgical treatment of root damage caused by orthodontic miniscrew placement.

INTRODUCTION: Miniscrews are being increasingly used for anchorage control in orthodontics. Despite the concern over root damage caused by miniscrews, there are few reports of precise clinical evaluations and appropriate management of that damage. In the case presented herein, the root damage caused by the placement of miniscrews was repaired by root canal treatment and surgical intervention. METHODS: A 44-year-old man received orthodontic treatment for intrusion of the left maxillary first molar with a miniscrew anchorage system. During that treatment, the miniscrews had fallen out and had to be reinserted more than 6 times in the same area. Two years later, the patient complained of a spontaneous pain in the maxillary left molar region. Although the patient received root canal treatment, intraoral sinus tracts could still be detected, and the patient's discomfort persisted. Periradicular surgery revealed that the persistent infection was related to root surface damage caused by orthodontic miniscrew placement. Healing was achieved by a combination of root canal treatment and surgical intervention. RESULTS: Scanning electron microscopy of the damaged distobuccal root apex revealed a mature biofilm consisting of a network of matrix that contained mostly rod-like and spherical bacteria. At a 12-month recall checkup, the patient was free of pain. A repeat periapical radiograph revealed reduction of the pretreatment radiolucent lesion. CONCLUSIONS: More careful planning of miniscrew placement is necessary to lessen the danger of root damage. Furthermore, a precise evaluation of both root and pulpal damage and careful consideration of the choice of optimal treatment modality are needed.

A comparative study of biofilm removal with hand, rotary nickel-titanium, and self-adjusting file instrumentation using a novel in vitro biofilm model.

INTRODUCTION: This study sought to present a standardized biofilm model in extracted teeth with an artificial apical groove to quantify the efficacy of hand, rotary nickel-titanium, and self-adjusting file (SAF) instrumentation in biofilm bacteria removal. METHODS: Thirty-six extracted single-rooted teeth with oblong canals were selected. Each tooth was split longitudinally, and a 0.2-mm-wide groove was placed in the apical 2 to 5 mm of the canal. After growing mixed bacteria biofilm inside the canal under an anaerobic condition, the split halves were reassembled in a custom block, creating an apical vapor lock. Teeth were randomly divided into 3 treatment groups (n = 10 per group) using the K-file, ProFile (Dentsply Tulsa Dental Products, Tulsa, OK), and the SAF (ReDent-Nova, Ra'anana, Israel). Irrigation consisted of 10 mL 3% NaOCl and 4 mL 17% EDTA. Six teeth received no treatment. Areas inside and outside the groove were examined using a scanning electron microscope. RESULTS: The scanning electron microscope showed a consistently thick layer of biofilm grown in the canals of the control group after 4 weeks. Within the groove, a smaller area remained occupied by bacteria after the use of the SAF compared with the ProFile and the K-file (3.25%, 19.25%, and 26.98%, respectively; P < .05). For all groups, significantly more bacteria were removed outside the groove than inside (P < .05). No statistical differences were found outside the groove (P > .05). CONCLUSIONS: Although all techniques equally removed bacteria outside the groove, the SAF reduced significantly more bacteria within the apical groove. No technique was able to remove all bacteria. This biofilm model represents a potentially useful tool for the future study of root canal disinfection.

Exuberant Biofilm infection in a lateral canal as the cause of short-term endodontic treatment failure: report of a case.

INTRODUCTION: This article describes a case in which signs and symptoms persisted in spite of the endodontic treatment following high standards to characterize a short-term failure. METHODS: After several appointments of root canal treatment in an attempt to resolve persistent symptoms, including 106 days of calcium hydroxide intracanal medication, periradicular surgery was performed, and the root apex and the lesion were subjected to histologic and histobacteriologic analyses. RESULTS: The lesion was diagnosed as a cyst, and the main root canal was free of bacteria and debris. CONCLUSIONS: The cause of the short-term failure was an exuberant bacterial biofilm colonizing a lateral canal in the apical root segment. This case report highlights one of the major problems of modern endodontic therapy; bacteria located in areas distant from the main root canal can remain unaffected by treatment procedures and maintain disease. The challenge for researchers and clinicians that arises from this problem is to develop strategies, instruments, or substances that can reach those areas and achieve sufficient reduction in the infectious bioburden to permit predictable periradicular healing.

Bacterial flora and extraradicular biofilm associated with the apical segment of teeth with post-treatment apical periodontitis.

INTRODUCTION: Microorganisms are able to survive and cause persistent infection in the extraradicular area. The aims of this study were to investigate the primary bacterial flora and the localization of extraradicular biofilm in persistent apical periodontitis lesions. METHODS: Apical root samples from root-end surgery were collected from 23 root-filled teeth with apical periodontitis. Five samples were examined for the presence of biofilm by scanning electron microscopy. Another 5 samples were examined for the presence of biofilm by Brown and Brenn-modified Gram staining. The DNA from 13 samples was processed for amplification via polymerase chain reaction and separated with denaturing gradient gel electrophoresis. Selected bands were excised from the gel and sequenced for identification. RESULTS: The extraradicular biofilm present on the external root surface of treated teeth consisted of abundant, amorphous extracellular material and multiple bacterial species. The following species were detected in the microbial community from the apical samples: Actinomyces sp. oral, Propionibacterium, Prevotella sp. oral, Streptococcus, Porphyromonas endodontalis, and Burkholderia. The prevalence of Actinomyces sp. oral and Propionibacterium were highest (84.6% and 61.5%, respectively). CONCLUSIONS: Extraradicular biofilm was present on the external root surface of treated teeth with persistent periapical lesions. Actinomyces sp. oral and Propionibacterium are likely important contributors to extraradicular biofilm formation and persistent periapical infection.

Persistent extraradicular infection in root-filled asymptomatic human tooth: scanning electron microscopic analysis and microbial investigation after apical microsurgery.

INTRODUCTION: Procedural accidents have a negative effect on healing and might contribute to the persistence of infections in inaccessible apical areas, requiring surgical intervention. This report describes a case of persistent apical periodontitis of a lower left first molar associated with the sinus tract and a periapical lesion that required nonsurgical endodontic retreatment and apical surgery for resolution. METHODS: The tooth had received endodontic treatment 3 years ago and had to be retreated using the crown-down technique with chemical auxiliary substance (2% chlorhexidine gel), foramen patency, and enlargement and was filled in a single appointment. The occlusal access cavity was immediately restored with composite resin. After 1 month, it could be observed that the sinus tract persisted and, radiographically, the lesion remained unaltered. Therefore, endodontic microsurgery was indicated. Apical microsurgery was performed under magnification with the use of a dental operating microscope including apicectomy, root end with ultrasound, and sealing with mineral trioxide aggregate. A microbiological sample was collected from the apical lesion. The resected distal root apex was observed by scanning electron microscopy. RESULTS: The following species were detected: Actinomyces naeslundii and Actinomyces meyeri, Propionibacterium propionicum, Clostridium botullinum, Parvimonas micra, and Bacteroides ureolyticus; scanning electron microscopic analysis revealed bacterial biofilm surrounding the apical foramen and external radicular surface. Gutta-percha overfilling at the apex because of a zip caused during initial endodontic treatment could be observed. A 6-month follow-up showed apparent radiographic periapical healing, which progressed after 24 months. CONCLUSION: Gram-positive anaerobic bacteria and extraradicular biofilm seem to participate in the maintenance of persistent periapical pathology, and endodontic retreatment followed by periapical microsurgery proved to be a successful alternative in the resolution of persistent extraradicular infections.

The efficacy of a cervical barrier in preventing microleakage of Enterococcus faecalis in endodontically treated teeth.

The clinical failure of coronal restorations can compromise the healthy periapical status of endodontically treated teeth. The purpose of the present ex vivo study was to assess the effectiveness of the cervical barrier in preventing bacterial microleakage in the eventual loss of the coronal restoration. Following removal of the smear layer and obturation to the cementoenamel junction using gutta-percha, 70 single-rooted mandibular premolars were randomly divided into five different groups: Group 1 received no additional treatment; Groups 2 and 3 had 2 mm and 3 mm of the obturation removed, respectively, followed by placement of a cervical barrier that was the same thickness as the obturation. In Group 4 (positive control), the root canals were filled only with gutta-percha, while in Group 5 (negative control), the root canals were completely impermeabilized following obturation. The filled root canals were incorporated into a split-chamber model system using Enterococcus faecalis as a microbial marker. The apices were suspended in the lower chambers. Leakage was determined daily for 60 days and evaluated for turbidity. According to Fisher's exact test, the cervical barrier in Groups 2 and 3 prevented the microleakage of E. faecalis into the root canals when compared with Groups 1 and 4. This result was similar to that for the completely sealed samples in Group 5 (p = 0.001).

Biofilms and apical periodontitis: study of prevalence and association with clinical and histopathologic findings.

INTRODUCTION: This study evaluated the prevalence of bacterial biofilms in untreated and treated root canals of teeth evincing apical periodontitis. The associations of biofilms with clinical conditions, radiographic size, and the histopathologic type of apical periodontitis were also investigated. METHODS: The material comprised biopsy specimens from 106 (64 untreated and 42 treated) roots of teeth with apical periodontitis. Specimens were obtained by apical surgery or extraction and were processed for histopathologic and histobacteriologic techniques. RESULTS: Bacteria were found in all but one specimen. Overall, intraradicular biofilm arrangements were observed in the apical segment of 77% of the root canals (untreated canals: 80%; treated canals: 74%). Biofilms were also seen covering the walls of ramifications and isthmuses. Bacterial biofilms were visualized in 62% and 82% of the root canals of teeth with small and large radiographic lesions, respectively. All canals with very large lesions harbored intraradicular biofilms. Biofilms were significantly associated with epithelialized lesions (cysts and epithelialized granulomas or abscesses) (p < 0.001). The overall prevalence of biofilms in cysts, abscesses, and granulomas was 95%, 83%, and 69.5%, respectively. No correlation was found between biofilms and clinical symptoms or sinus tract presence (p > 0.05). Extraradicular biofilms were observed in only 6% of the cases. CONCLUSIONS: The overall findings are consistent with acceptable criteria to include apical periodontitis in the set of biofilm-induced diseases. Biofilm morphologic structure varied from case to case and no unique pattern for endodontic infections was identified. Biofilms are more likely to be present in association with longstanding pathologic processes, including large lesions and cysts.

Surgical endodontic treatment of refractory periapical periodontitis with extraradicular biofilm.

OBJECTIVE: This study explored the effect of surgical endodontic treatment of refractory periapical periodontitis with extraradicular biofilm. STUDY DESIGN: Endodontic surgery was conducted on a case of refractory periapical periodontitis with extraradicular biofilm. During the procedure, the samples of periapical tissues were collected for microbiologic analysis. The resected root ends were observed under scanning electron microscope. The patient was recalled every 3 months to evaluate the treatment effect for 1 year. RESULTS: The samples yielded 1 type of facultative anaerobic bacteria (Streptococcus sanguis) and 2 types of obligate anaerobic bacteria (Porphynomonas endodontalis and Prevotella oralis). Mature bacteria biofilms were formed on the surface of the root apexes. At the 1-year recall visit, the radiograph and the clinic examination showed the refractory periapical periodontitis was cured successfully. CONCLUSIONS: The periapical bacterial biofilm may contribute to the refractory periapical periodontitis. Endodontic surgery is a good option for definitive removal of an established extraradicular infection.

Bacterial leakage in obturated root canals-part 2: a comparative histologic and microbiologic analyses.

OBJECTIVE: In this study, presence of dentin infection in root canals, obturated with 4 techniques submitted to the bacterial leakage test, was evaluated using histologic methods. STUDY DESIGN: The canals of palatal roots of 160 molars were instrumented and divided into different groups, according to the obturation technique used (lateral condensation, MicroSeal system, Touch 'n Heat + Ultrafil, and Tagger's hybrid technique) and extent of the remaining obturation material (5 mm and 10 mm). Ten additional roots were used as control samples. The roots were sterilized in ethylene oxide and mounted on a device for evaluation of bacterial leakage using the bacteria Enterococcus faecalis for 120 days. After the leakage test, roots were microscopically analyzed for the presence of dentin infection in the root canals and dentinal tubules. RESULTS: A total of 154 specimens were analyzed using both methodologies in the experimental groups; 50 root canals (32.4%) showed bacterial leakage at the end of the experimental period, and 118 (76.6%) showed the presence of bacteria in the root canals using the histologic criteria. The lateral condensation technique allowed lower penetration of bacteria in the root canals and dentinal tubules, followed by Touch 'n Heat + Ultrafil, MicroSeal, and Tagger's hybrid technique, which allowed significantly greater penetration of bacteria. Root canals with 10 mm of remaining obturation material presented similar bacterial penetration as root canals with 5 mm. CONCLUSIONS: Even when an adequate seal of the apical foramen was shown by the absence of turbidity in the bacterial leakage test, E. faecalis dentin infection was present in a high percentage of the root canals after 120 days of root filling exposure to the bacteria. Tagger's hybrid technique presented greater quantity of bacteria in histologic sections than root canals obturated with the other techniques.