Apical Actinomycosis as a Continuum of Intraradicular and Extraradicular Infection: Case Report and Critical Review on Its Involvement with Treatment Failure

Identification of the genes involved in the biofilm-like structures on actinomyces oris K20, a clinical isolate from an apical lesion

INTRODUCTION

Although the production of biofilm is thought to be crucial in the pathogenesis of abscess formations caused by oral resident microorganisms, the particular mechanisms are still unknown. The aim of this study was to identify gene(s) responsible for maintaining the cell surface-associated meshwork-like structures, which are found in some biofilm-producing bacteria, in a clinical isolate of Actinomyces oris K20.

METHODS

Random insertional mutagenesis by using transposon EZ-Tn5 was performed against the strain K20. Transposon insertion mutants were screened by scanning electron microscopy for the absence of cell surface-associated meshwork-like structures. The disrupted genes by the transposon insertion were determined by direct genome sequencing with the transposon-end primers.

RESULTS

Five mutants without the meshwork-like structures were identified from 175 mutants. Sequencing of flanking regions of transposon insertion revealed that 3 mutants had a gene encoded polysaccharide deacetylase, Spo0J containing ParB-like nuclease domain, and hypothetical protein, respectively. The other 2 mutants had an insertion in a noncoding region and an unidentified region, respectively.

CONCLUSIONS

Our findings indicated that these genes might be involved in the formation of meshwork-like structures on Actinomyces oris K20.

Periapical actinomycosis

Actinomycosis is a rare chronic infection caused by species of Actinomyces and characterised by abscess formation, tissue fibrosis, suppurative lesions and fistulas with purulent discharge containing sulphur granules. Owing to its multiform manners of presentation and non-specificity from its clinical features, it has been considered as a challenging diagnosis. Periapical actinomycosis is one of the rarest forms of actinomycosis occurring in the maxillofacial region. In its occurrence it presents in the form of persistent and recurrent draining fistula in the periapical region. We report a case of periapical actinomycosis occurred in endodontically treated teeth and accidentally found to be actinomycosis during histopatological examination. An insight towards the portal of entry of the organisms into the periapical region is also discussed. The practice of sending even a tiny bit of tissues to histopathology obtained from periapical surgery will very well demonstrate this disease and help in rapid resolution through appropriate antibiotic therapy.

Endodontic surgery failure: SEM analysis of root-end filling

This study investigated the quality of root-end filling in cases of periapical lesions persisting after endodontic surgery. Ten patients requiring extraction of an endodontically treated tooth were included. The root-ends of extracted teeth were examined by scanning electron microscopy. Defects at the interface between the root-end filling and cavity margin were classified as ideal, imperfect (some marginal disruption) or inadequate (continuous marginal disruption involving >30% of the interface). Four cases were scored as imperfect, and six were scored as inadequate. A defective apical seal could favour continuous leakage of surviving bacteria and their by-products from the infected root canal system to periapical tissues, thereby sustaining inflammation.

Morphological features of the maxillary incisors roots and relationship with neighbouring anatomical structures: possible implications in endodontic surgery

The purpose of this study was to investigate the relationship between the root apex of the upper incisors and neighbouring anatomical structures as well as the morphology of the root-end foramen after apicoectomy. Fifty-seven patients requiring endodontic surgical treatment for a maxillary anterior root were enrolled. A preoperative diagnostic computed tomography (CT) scan was analysed to determine: the distance between the anterior wall of the nasopalatine duct and the central (CI-ND) incisor root 4mm from the apex; and the distance between the floor of the nasal cavity and the tip of either the central (CI-NF) or the lateral (LI-NF) incisor root. After apicoectomy, root-end foramen endoscopic pictures were taken in order to characterize their morphology. Fifty-nine central and 26 lateral incisors were evaluated. The average CI-ND was 4.71 ± 1.26 (SD) mm. The average CI-NF was 10.62 ± 2.25 mm. The average LI-NF was 13.05 ± 2.43 mm. The foramen shape after apicoectomy was ovoid to circular in about 90% of cases in both central and lateral incisors. A sound knowledge of the anatomical relationships at the surgical site is essential for the clinician to perform a safe endodontic surgical procedure.

Implant failure associated with actinomycosis in a medically compromised patient

Oral actinomycosis is not a common disease, but it can cause massive destruction. This article reports a case of implant failure associated with actinomycosis. A 55-year-old Caucasian male patient had tooth #20 extracted years ago and an implant placed 3 years ago. The #20 implant area developed an abscess about 1½ years after implant placement. Radiographic findings revealed a large radiolucency on the mesial aspect of the #20 implant. The implant was surgically removed and the lesion thoroughly debrided. The patient experienced severe pain when the apical soft tissue was curreted following implant removal. A periapical radiograph revealed that the lesion approached the mental foramen. A short course of antibiotics was prescribed. Histological observation found sulfur granules, which were found to be actinomycotic colonies. Peri-implant actinomycosis was diagnosed. No recurrence had occurred at the 1-year follow-up.

Distinctive features of the microbiota associated with different forms of apical periodontitis

Microorganisms infecting the dental root canal system play an unequivocal role as causative agents of apical periodontitis. Although fungi, archaea, and viruses have been found in association with some forms of apical periodontitis, bacteria are the main microbial etiologic agents of this disease. Bacteria colonizing the root canal are usually organized in communities similar to biofilm structures. Culture and molecular biology technologies have demonstrated that the endodontic bacterial communities vary in species richness and abundance depending on the different types of infection and different forms of apical periodontitis. This review paper highlights the distinctive features of the endodontic microbiota associated with diverse clinical conditions.