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Amplifiable DNA is preserved after cell death, but the critical determinant is the form of DNA. Free DNA undergoes spontaneous and enzymatic decomposition, whereas cell-bound E. faecalis DNA persists for long periods.

Introduction: Molecular methods are increasingly being deployed for analysis of the microbial flora in the root canal. Such methods are based on the assumption that recovered DNA is associated with the active endodontic infection, yet paleomicrobiology research is based on the recovery of ancient DNA from centuriesold tooth and bone samples, which points to considerable longevity of the DNA molecule in these tissues. The main component of dentin and bone is the mineral hydroxyapatite. This study assessed DNA binding to hydroxyapatite and whether thiS binding affinity stabilizes the DNA molecule in various media.

Methods: DNA was extracted from Fusobacterium nucleatum and added to ceramic hydroxyapatite for 90 minutes. The DNA-bound hydroxyapatite was incubated in different media (ie, water, sera, and DNase I) for up to 3 months. At predetermined intervals, the recovery of detectable DNA was assessed by releasing the DNA from the hydroxyapatite using EDTA and evaluating the presence of DNA by gel electrophoresis and polymerase chain reaction (PCR) amplification.

Results: When incubated with hydroxyapatite, nonamplified DNA was detectable after 3 months in water, sera, and DNase I. In contrast, DNA incubated in the same media (without hydroxyapatite) decomposed to levels below the detection level of PCR within 3 weeks, with the exception of DNA in sera in which PCR revealed a weak positive amplification product.

Conclusions: These results confirm a specific binding affinity of hydroxyapatite for DNA. Hydroxyapatite-bound DNA is more resistant to decay and less susceptible to degradation by serum and nucleases, which may account for the long-term persistence of DNA in bone and tooth.

The microbiota inhabiting the untreated root canal differ markedly from those found in post-treatment disease, yet there is limited information on the microbial characteristics distinguishing the different infections. We hypothesized that starvation survival is a key microbial property in species selection. This study analyzed starvation-survival behavior over 60 days of species representative of the untreated root canal infection: Fusobacterium nucleatum, Peptostreptococcus anaerobius, Prevotella intermedia and Pseudoramibacter alactolyticus. All species did not survive 1 day in water. In 1% serum, the 4 species could not survive beyond 2-3 weeks. They required a high initial cell density and >or=10% serum to survive the observation period. The results highlight a poor starvation-survival capacity of these 4 species compared with species prevalent in post-treatment infection, which are well equipped to endure starvation and survive in low numbers on minimal serum. These findings point to starvation-survival capacity as a selection factor for microbial participation in post-treatment disease.

Apical periodontitis, an acute or chronic inflamination around the apex of the tooth, is caused by bacteria in the root canal. In Sweden the dentists devote around 10X of their total time to treating this disease. The treatment usually requires 3 to 5 sessions. The treatment may fail in up to 25X of the cases. In the present study various treatment regimens were evaluated. One hundred and forty singlerooted teeth with apical periodontitis were treated. The importance of mechanical instrumentation, irrigating solutions and antibacterial dressings in eliminating bacteria from the infected root canals was studied using bacteriological techniques. The healing of the apical periodontitis after treatment was followed for 2 to 5 years on recall radiographs.

Bacteria were found in all 140 root canals at the beginning of the treatment. Most of these bacteria were anaerobes and they represented a restricted group of bacteria compared to the bacteria present at other sites in the oral cavity. Mechanical instrumentation with files and reamers in combination with saline irrigation reduced the number of bacterial cells in the root canal 100- to 1000-fold during one treatment session. Bacteria could be eliminated from about half the number of root canals if this treatment was performed at 4 sessions.

Mechanical instrumentation and irrigation with 0.5X or 5X sodium hypochlorite solutions or with the 5X solution in combination with 15X EDTA solution wa3 more efficient and the bacteria were eliminated from about half the treated canals after one treatment session. The bacteria which persisted in the root canal after this treatment usually increased in number during the interval up to the next session and reached levels which were often as high as in the initial sample at the previous session.

All bacteria persistent in the root canals after the previous treatment regimens were with 2 exceptions eliminated by dressing the root canals for 1 to 2 months with calcium hydroxide paste. Thirty-four out of 35 root canals treated at the first session with mechanical instrumentation, irrigation with sodium hypochlorite solution and dressed with calcium hydroxide paste were free of bacteria at the second session. Calcium hydroxide paste was superior to camphorated phenol and camphorated paramonochlorophenol as dressing.

Healing of 79 out of the 140 treated teeth was followed for 2 to 5 years. The majority of the lesions healed completely or decreased in size in such a way that they could be expected to heal. There was no or only an insignificant decrease in the size of the lesions in 5 cases. In 2 of these cases bacteria were demonstrated in the periapical tissues and in a third case dentin chips. Periapical lesions may thus fail to heal in a few cases due to an establishment of bacteria outside the root canal, and in that site the bacteria are inaccessible to conventional endodontic treatment.

The present study showed that treatment of the majority of infected non-vital teeth can be completed in only 2 sessions, if mechanical instrumentation, sodium hypochlorite irrigation and calcium hydroxide dressing are combined.

BACKGROUND/AIMS: Culture-difficult bacteria, including asaccharolytic anaerobic gram-negative coccobacilli (AAGNC), may constitute a predominant group of organisms in oral sites. This study aimed to characterize phylogenetically 10 AAGNC isolated from endodontic lesions and periodontal pockets. METHODS: 16S rDNA sequence and G + C content were determined. Strains sharing more than 98% sequence similarities and similar G + C content were considered the same bacterial species. RESULTS: One isolate resembled Dialister pneumosintes (the type species of the genus Dialister) with 35 mol% G + C content and 97% sequence similarity. Of eight isolates having 45-47 mol% G + C content, seven were identified as D. invisus and one resembled Dialister invisus with 97% sequence similarity. However the 16S rDNA sequence similarities with D. pneumosintes were relatively low, indicating the strains may belong to a new genus. The last isolate revealed 35 mol% G + C content, but had higher 16S rDNA sequence similarity with D. invisus than with D. pneumosintes. CONCLUSION: The group of oral AAGNC isolates need to be reclassified

OBJECTIVE: This study aimed to emphasize the importance of seeing mucosal lichen planus (LP) as a systemic disease and not an isolated oral or genital disease and to analyze the proportion of thyroid antibodies among patients with multimucosal LP.

MATERIALS AND METHODS: All patients examined by the authors and diagnosed with mucosal LP within 1 year were consecutively included. Full medical histories were collected with special emphasis on autoimmune and thyroid diseases. Sera were analyzed for thyroid antibodies and underwent serologic test for herpes virus. The control group comprised 83 healthy volunteers matched regarding sex and age.

RESULTS: Of the patients, 120 were included, 89 (74%) of whom were women and 31 (26%) were men. The vast majority of the patients had multifocal lesions, whereas oral lesions solely were found in 28% of women and 36% of men. Of the patients, 28% had at least 1 additional autoimmune disease. Approximately half of the women were treated with levothyroxine owing to thyroid disease. Antibodies against herpes simplex virus were found in 60% of the patients and 44% of the controls (p < .03).

CONCLUSIONS: Lichen planus with mucosal involvement should be considered and taken care of as a systemic disease and not as an isolated oral and/or genital lichen. Contradictory to many former reports, most of our patients have a multimucosal disease that emphasizes the need for a multidisciplinary clinic to get optimal care and treatment.

Lichen planus is a chronic inflammatory disease of mucosa and skin affecting approximately 1-2% of the adult population. Autoimmunity has been implicated in the etiology of this disease, and recently we detected antibodies directed against all six p63 isoforms in sera from 2 out of 20 patients diagnosed with oral lichen planus (OLP) using Western blot analysis. Here we have developed an ELISA method for screening sera for presence of autoantibodies directed against p63. Using the same sera as previously analysed, we show that the optical density ratios for sera from the two patients with known autoantibodies was considerably higher compared to mean optical density ratios for all samples as well as controls analysed. Applying this novel ELISA technique for screening of sera from an additional group of 46 patients with oral and/or genital or skin lichen and 43 matched controls, we detected another three patients with autoantibodies against the p63 proteins. These data are discussed together with the observation that all five patients with detectable p63 autoantibodies from our two studies had clinically severe disease symptoms.

J Oral Pathol Med (2010) Oral lichen planus (OLP) is a relatively common chronic disease of the oral mucosa for which the aetiopathogenesis is not fully understood. It mainly affects middle aged and elderly. The finding of autoantibodies against p63, a member of the p53 family, is a strong indication of autoimmunity as a causative or contributing factor. The WHO classified OLP as a potentially malignant disorder, but still there is an ongoing debate in the literature on this subject. The TP53 gene encodes a tumour suppressor protein that is involved in induction of cell-cycle arrest or apoptosis of DNA-damaged cells. The p63 gene encodes six different proteins that are crucial for formation of the oral mucosa and skin. The coordinated stabilization of p53 and decreased expression of p63 seen in OLP cause induction of apoptosis enabling removal of DNA-damaged cells. In view of the complexity of cancerogenesis, no firm statement can at present be made about the relevance of the observed relationship between p53 and p63 and the possible malignant transformation of OLP.

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 Grampositive 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.

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.

Background: Mucosal lichen planus is a severe variant of lichen planus, Lichen planus (LP), which in many ways affect patients' lives. The aetiology is not fully understood, and there is no treatment clearing the disease once and for all. Oral LP has by the WHO been classified as a precancerous lesion. Micro-RNAs, miRNAs, are non-coding, small single-stranded RNAs involved in biological processes like apoptosis, proliferation, differentiation, metastasis, angiogenesis and immune response.

Methods and Results: In sera from 30 patients with multifocal mucosal LP, 15 miRNAs were identified as significantly differentially expressed compared with controls. The three most up-regulated miRNAs are all connected to oral squamous cell carcinoma or epithelial carcinoma in general.

Discussion: Even if no specific LP-associated miRNA profile was found, data clearly indicate that miRNAs could play a role in the earlier phases of lichen planus.

Background/Aim: To evaluate the long-term survival of immature traumatized incisors with pulp necrosis and apical periodontitis after endodontic treatment with two apexification techniques (calcium hydroxide apexification and MTA-apical plug) and to identify major factors affecting the survival of these teeth.

Materials and Methods: Records of 2400 children and adolescents were screened for presence of traumatic dental injuries to immature incisors where endodontic treatment with the two apexification techniques was performed during January 2003 and December 2022, compared to a control group of mature teeth treated with conventional endodontic techniques. The studied variables were age; sex; apexification technique, presence of luxation and hard tissue injuries; preoperative root development stage (RDS), preoperative and postoperative periapical index (PAI), the time-point for tooth loss, and overall survival time in years. Kaplan–Meier estimates were used to graphically present the survival functions and Cox proportional hazard model to calculate hazard ratios (HR, 95% CI).

Results: The median survival time was 10 years for calcium hydroxide apexification, 16.1 for MTA-apexification, for luxation injuries other than intrusions and avulsions 15.5 years, for intrusions 12.5 years and for avulsions 6.8 years. The variables with significant negative impact on tooth survival were calcium hydroxide apexification, avulsion and postoperative PAI 3–5. No significant relationships were found for the variables MTA apexification, concussion; subluxation; lateral luxation; extrusion, intrusion, hard tissue injuries, preoperative RDS and PAI scores and postoperative PAI 1–2. After adjustment, the risk for premature tooth loss was 13.5 times higher in calcium hydroxide apexification, approximately 2 to 4 times higher in PAI 3–5, and 5.6 times higher in avulsions.

Conclusions: Calcium hydroxide apexification, avulsion, and postoperative PAI 3–5 were identified as prognostic variables with significant negative impact on the risk for premature tooth loss.

The fate of DNA from bacteria that infect the root canal but cannot survive is currently unknown, yet such information is essential in establishing the validity of polymerase chain reaction (PCR)-based identification methods for root canal samples. This in vitro study tested the hypothesis that PCR-detectable DNA from dead bacteria might persist after cell death and investigated the efficiency of sodium hypochlorite (NaOCl) as a field decontamination agent. Using heat-killed Enterococcus faecalis, the persistence of DNA encoding the 16S rRNA gene was monitored by PCR. While most probable number analysis showed an approximate 1000-fold decay in amplifiable template, E. faecalis DNA was still PCR-detectable 1 year after cell death. NaOCl (1%) eliminated amplifiable DNA within 60 seconds of exposure. Our findings also disclosed a previously overlooked problem of concentration-dependent inhibition of the PCR reaction by thiosulfate-inactivated NaOCl. These results highlight the challenges of reliably identifying the authentic living root canal flora with PCR techniques.