Pia Titterud Sunde

Microbiota of periapical lesions refractory to endodontic therapy.

The periapical microbiota of 36 teeth with refractory apical periodontitis was investigated. None of the teeth had responded to conventional endodontic or long-term (> 6 months), calcium-hydroxide treatment. Eight patients had received antibiotics systemically. After anaerobic culture, a total of 148 microbial strains were detected among 67 microbial species. One of the 36 lesions was culture-negative. Approximately half (51.0%) of the bacterial strains were anaerobic. Gram-positive species constituted 79.5% of the flora. Facultative organisms, such as Staphylococcus, Enterococcus, Enterobacter, Pseudomonas, Stenotrophomonas, Sphingomonas, Bacillus, or Candida species were recovered from 27 of the lesions (75%). Sulfur granules were found in 9 lesions (25%). In these granules Actinomyces israelii, A. viscosus, A. naeslundii, and A. meyeri were identified. Other bacterial species, both gram-positive and gram-negative, were detected in the granules as well. Two sulfur granules did not contain Actinomyces. Scanning electron microscopy demonstrated rod- and spirochete-like cells in the granules, and transmission electron microscopy revealed organisms with copious amounts of extracellular material. Outer membrane vesicles were also seen. Some of the granules were calcified. This study demonstrated a wide variety of microorganisms, particularly gram-positive ones, in the periapical lesions of teeth with refractory apical periodontitis.

Assessment of periradicular microbiota by DNA‐DNA hybridization

Abstract – In the present study the “checkerboard” DNA‐DNA hybridization technique was used to identify bacteria in periapical endodontic lesions of asymptomatic teeth. Thirty‐four patients with root‐filled teeth and apical periodontitis were divided into two groups, each containing 17 patients. In Group 1, a marginal incision was performed during surgery to expose the lesion, and in Group 2, a submarginal incision was applied. The gingiva and mucosa were swabbed with an 0.2% chlorhexidine gluconate solution prior to surgery. Bacterial DNA was identified in all samples from the two groups using 40 different whole genomic probes. The mean number (±SD) of species detected was 33.7±3.3 in Group 1 and 21.3±6.3 in Group 2 (P<0.001). The majority of the probe‐detected bacteria were present in more lesions from Group1 than from Group 2. The differences were most notable for Campylobacter gracilis, Porphyromonas endodontalis, Propionibacterium acnes, Capnocytophaga gingivalis, Fusobacterium nucleatum ssp. nucleatum, Fusobacterium nucleatum ssp. polymorphum, Prevotella intermedia, Treponema denticola, Streptococcus constellatus and Actinomyces naeslundii I. Bacterial species such as Actinobacillus actinomycetemcomitans and Bacteroides forsythus were detected in more than 60% of the lesions from both groups. Also, P. endodontalis was abundant in periapical tissue. The data supported the idea that following a marginal incision, bacteria from the periodontal pocket might reach the underlying tissues by surgeon‐released bacteremia. The study provided solid evidence that bacteria invade the periapical tissue of asymptomatic teeth with apical periodontitis. The detection of much more bacteria with the “checkerboard” DNA‐DNA hybridization method than has previously been recovered by anaerobic culture indicated that the endodontic (and periodontal) microfloras should be redefined using molecular methods.

Human Cytomegalovirus and Epstein-Barr Virus in Apical and Marginal Periodontitis: A Role in Pathology?

Periodontitis is presumably caused by bacterial infection, but it has been shown recently that affected tissue often contains human cytomegalovirus (HCMV) and Epstein–Barr virus (EBV). The present study was initiated to evaluate the role of these viruses in the pathogenesis of periodontitis. HCMV and EBV were quantified in 40 apical and 25 marginal periodontitis samples using real time PCR. In situ hybridization or immunohistochemistry was carried out on apical samples to detect viral presence within cells. A possible association with relevant bacteria was examined. Of the apical periodontitis samples, 50% contained EBV, while none contained HCMV. Of the marginal periodontitis samples, 40% were positive for EBV and 12% for HCMV. With one exception, however, the amount of virus was close to the detection limits. EBV was only detected in 1 out of 15 healthy periodontium samples. Immunohistochemistry and in situ hybridization were all negative. Significant associations were found between periodontal EBV and the presence of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Although there was an obvious association of the virus with clinical samples, it seems unlikely that these viruses play a major role in the pathogenesis of periodontitis of the average patient. Their presence may reflect that the clinical samples contain more blood or saliva compared to controls, or an accumulation of lymphoid cells harboring virus in the inflamed tissue. J. Med. Virol. 80:1007–1011, 2008.

Patient with severe periodontitis and subgingival Epstein-Barr virus treated with antiviral therapy

It has been suggested that the presence of Epstein-Barr virus (EBV) can increase the severity of marginal periodontitis. We administered antiviral treatment (Valtrex for a period of 10 days) to a patient with recurrent periodontal disease and a high EBV load subgingivally. The antiviral treatment decreased the presence of EBV to the detection limit and the periodontal condition improved dramatically. One year after treatment, the periodontal condition was still stable and the virus barely detectable. The case suggests that virus screening and subsequent antiviral therapy may be useful as an adjunct to conventional periodontal therapy.

Human papillomavirus subtypes in oral lesions compared to healthy oral mucosa

BACKGROUND Human papillomaviruses (HPV) are involved in the etiology of cervix cancer, but it is still unclear whether they play a role in related oral lesions. OBJECTIVES The presence of HPV in oral leukoplakia biopsies (n=50) and oral squamous carcinoma biopsies (n=50) was compared to normal oral mucosa swabs (n=50) for the purpose of indicating a possible etiological role for the virus. STUDY DESIGN DNA was extracted from tissue biopsies and from mucosa swabs of control samples. Nested PCR was performed with primers targeting conserved sequences within the capsid gene L1. PCR products were sequenced to identify the HPV genotype. RESULT The results reveal a profile of low-risk HPV genotypes in oral leukoplakia similar to that in healthy controls, while HPV was less frequently observed in oral squamous carcinoma. CONCLUSIONS HPV does not seem to represent an important causal factor for the development of oral leukoplakia or oral squamous carcinoma.

Bacterial diversity in persistent periapical lesions on root-filled teeth

Abstract Background: The purpose of this study was to analyze the bacterial diversity in persistent apical lesions on root-filled teeth by using culture-independent molecular methods. Design: Twenty surgically removed apical lesions from therapy-resistant teeth were examined for the presence of bacterial DNA using PCR targeting the 16s ribosomal RNA gene, followed by cloning and sequencing. Results: Bacterial DNA was detected in 17 of the 20 samples (85%). A total of 236 clones were analyzed. Seven different bacterial phyla were represented and a total of 75 different bacterial taxa were identified; 36% of the species have not yet been cultivated. Commonly detected bacterial species included Fusobacterium spp., Prevotella spp., Tannerella forsythia, Porphyromonas endodontalis, Treponema denticola, Bacteroidetes spp., Peptostreptococcus spp., and Streptococcus spp. Conclusions: A wide range of bacteria was identified in periapical lesions on therapy-resistant teeth. These bacteria may contribute in the etiology of periapical infection and impede healing of these lesions.

Anatomic Comparison of Contralateral Premolars

Introduction The comparative anatomy of contralateral premolars has not been previously studied. The purpose of this micro–computed tomography investigation was to qualitatively and quantitatively assess and compare the morphology of contralateral premolars in terms of length, canal width, dentinal thicknesses, accessory canals, root canal configurations, isthmi, C‐shapes, root canal orifices, and apical foramina. The null hypothesis (H0) is that contralateral premolars are more morphologically similar than randomly assigned pairs for simple morphometric measurements (lengths, canal widths, and dentinal thickness). Methods Forty‐one intact premolar pairs (n = 82) extracted from 28 patients were scanned with micro–computed tomography and reconstructed. Quantitative comparative assessment of measurements was performed by pairwise statistical analysis of contralateral and random pairs with Student t test and one‐sample t test. All measured parameters (lengths, widths, and thicknesses) were normalized by Z score so that they could all be compared on a common scale. A correlation study was also performed. Canal configurations and isthmi were classified according to preexisting classification schemes. The number and location of accessory canals and apical foramina were registered and compared. Results/Conclusions Contralateral premolar pairs demonstrated a high degree of similarity in terms of the linear measurements (lengths, widths, and thicknesses). The apical portion (foramina, C‐shapes, and accessory canals) did not demonstrate bilateral symmetry. The comprehensive statistical analysis of the normalized parameters by Z score showed no statistically significant differences between the contralateral premolar pairs. The null hypothesis (H0) was accepted. HighlightsContralateral premolars’ linear measurements show a high degree of bilateral symmetry.Root canal configurations and orifice shapes of contralateral premolars demonstrate symmetry.Contralateral premolars have a wide array of variation in their apical portions.