Pro-inflammatory and anti-inflammatory cytokine expression in post-treatment apical periodontitis.

OBJECTIVE: This study evaluated the expression of pro-inflammatory (IL-1ß, IL-6, IFN-γ and TNF-α) and anti-inflammatory (IL-4 and TGF-ß) cytokines in apical periodontitis lesions. Correlations between these cytokines and clinical and cone-beam computed tomographic (CBCT) data were also assessed. MATERIAL AND METHODS: Apical periodontitis lesions' data were obtained from 27 patients subjected to periradicular surgery. Specimens were processed for histopathologic and immunohistochemical analysis. Sections were evaluated according to the amount of positive staining for each antibody. Expression levels of the target mediators were compared with clinical and CBCT data. RESULTS: Twenty lesions were diagnosed as granuloma and 7 as cyst. In granulomas, IL-4 expression was significantly higher than IL-6 (p=0.001) and TNF-α (p=0.001). There was a significant relationship between high levels of TNF-α and lesions <5 mm (p=0.017). In cysts, IL-6 expression was significant lower than IL-4 (p=0.001) and IFN-γ (p=0.004). There was a significant relationship between high levels of TGF-ß and endodontic treatment performed ≤4 years before (p=0.045). In general, IL-4 was the most expressed mediator in both cysts and granulomas. CONCLUSIONS: There was a balance between the expression of pro-inflammatory and anti-inflammatory cytokines associated with the chronic periradicular inflammatory process. TNF-α and TGF-ß were related to some clinical and CBCT data.

Biofilm biomass disruption by natural substances with potential for endodontic use.

This study evaluated the in vitro effects of four natural substances on the biomass of bacterial biofilms to assess their potential use as root canal irrigants. The following substances and their combinations were tested: 0.2% farnesol; 5% xylitol; 20% xylitol; 0.2% farnesol and 5% xylitol; 0.2% farnesol, 5% xylitol, and 0.1% lactoferrin; 5% xylitol and 0.1% lactoferrin; and 20 mM salicylic acid. The crystal violet assay was used to evaluate the effects of these substances on the biomass of biofilms formed by Enterococcus faecalis and Staphylococcus epidermidis. All substances except for 20 mM salicylic acid and 20% xylitol reduced biofilm mass when compared to controls. The combination of farnesol and xylitol was the most effective agent against E. faecalis ATCC 29212 (p < 0.05). Farnesol combined with xylitol and lactoferrin was the most effective against biofilms of the endodontic strain of E. faecalis MB35 (p < 0.05). Similarly, combinations involving farnesol, xylitol, and lactoferrin reduced the biomass of S. epidermidis biofilms. In general, farnesol, xylitol, and lactoferrin or farnesol and xylitol reduced biofilm biomass most effectively. Therefore, it was concluded that combinations of antibiofilm substances have potential use in endodontic treatment to combat biofilms.

Microbial colonization in orthodontic mini-implants.

Peri-implant inflammation contributes for loss of secondary stability of orthodontic mini-implants. The investigation of microbial colonization in this area would benefit its control, and consequently favor the long-term success of mini-implants. Therefore, the aim of this study was to determine the establishment and the evolution of microbial colonization process in orthodontic mini-implants for 3 months, since the time of their installation. One-hundred and fifty samples collected from 15 mini-implants were investigated from baseline up to 3 months. The biological material was obtained from peri-implant area using paper points. Nonspecific, Streptococcus spp, Lactobacillus casei and Candida spp colonizations were analyzed by cell growth methods. Porphyromonas gingivalis colonization was observed by 16S rDNA-directed polymerase chain reaction. Data from cell growth were submitted to the Wilcoxon sign rank test and results from molecular analysis were presented in a descriptive way. There was no significant difference in the microbial colonization among the examined time intervals, except for Streptococcus spp, between baseline and 24 h, which characterized the initial colonization in this time interval. Lactobacillus casei and Candida spp colonizations were insignificant. No Porphyromonas gingivalis was detected among the analyzed samples. The microbial colonization of mini-implants did not significantly change during the study. However, it should be monitored by orthodontists, since it is an important factor for mini-implants success.

Development of periradicular lesions in normal and diabetic rats.

Evidence suggests that diabetic patients are more significantly affected by problems of endodontic origin. This study sought to radiographically and histologically examine the development of periradicular inflammation in control and in diabetic rats after induction of pulpal infection. The pulps of the mandibular first molars of normal and streptozotocin-induced diabetic rats were exposed and left in contact with their oral cavities for 21 and 40 days. Afterwards, the animals were sacrificed, the mandibles were surgically removed, fixed in formalin and then radiographed in a standardized position. The radiographic images of the periradicular lesions were scanned and computerized images were evaluated for the total area of the lesions using a specific software. Representative specimens were also prepared for histopathological analysis. Radiographic analysis revealed that diabetic rats presented significantly larger periradicular lesions when compared with control rats, regardless of the experimental period (p<0.05). Histopathological examination of representative specimens revealed larger periradicular lesions and more severe inflammatory exudate in the group of diabetic rats when compared with the control group. Data from the present study indicated that diabetic rats can be more prone to develop large periradicular lesions, possibly due to reduction in the defense ability against microbial pathogens.

Direct genotoxicity and mutagenicity of endodontic substances and materials as evaluated by two prokaryotic test systems.

Substances and materials used in endodontic therapy come into close contact with the periradicular tissues via apical foramen and foramina. Consequently, they should possess biocompatibility. There are currently few studies describing the genotoxic and mutagenic potentials of substances and materials used in endodontics. The purpose of this study was to evaluate the direct genotoxic and mutagenic properties of several substances and materials used in different phases of the endodontic treatment. For this intent, two prokaryotic test systems were used: the SOS chromotest and the Ames test. No metabolization with S9 was investigated, since only the direct effects of the substances and materials were surveyed. Most of the substances and materials tested presented mild to moderate cytotoxicity and genotoxicity as revealed by the SOS chromotest. Formocresol was the only tested substance to present severe genotoxicity to the tester bacterial strains. However, no substance or material tested showed direct mutagenicity as revealed by the Ames test.

A 16S rDNA-based nested PCR protocol to detect Campylobacter gracilis in oral infections.

The aim of this study was to describe a 16S rDNA-based nested polymerase chain reaction (nPCR) assay to investigate the occurrence of Campylobacter gracilis in oral infections. Samples were collected from ten infected root canals, ten cases of acute periradicular abscesses and eight cases of adult marginal periodontitis. DNA extracted from the samples was initially amplified using universal 16S rDNA primers. A second round of amplification used the first PCR products to detect C. gracilis using oligonucleotide primers designed from species-specific 16S rDNA signature sequences. The nPCR assay used in this study showed a detection limit of 10 C. gracilis cells and no cross-reactivity was observed with nontarget bacteria. C. gracilis was detected in the three types of oral infections investigated - 4/10 infected root canals; 2/10 acute periradicular abscesses; and 1/8 subgingival specimens from adult periodontitis. The method proposed in this study showed both high sensitivity and high specificity to directly detect C. gracilis in samples from root canal infections, abscesses, and subgingival plaque. Our findings confirmed that C. gracilis may be a member of the microbiota associated with distinct oral infections, and its specific role in such diseases requires further clarification.

Comparison of the effectiveness of bacterial culture, 16S rDNA directed polymerase chain reaction, and checkerboard DNA-dNA hybridization for detection of Fusobacterium nucleatum in endodontic infections.

Fusobacterium nucleatum is a Gram-negative, non-spore-forming, nonmotile, obligatory anaerobic rod that is normally isolated from the oral cavity. Epidemiological studies have shown that this species is one of the most prevalent in primary root canal infections. The purpose of this study was to compare the effectiveness of bacteriological culture, 16S rDNA directed polymerase chain reaction and checkerboard DNA-DNA hybridization for detection of F. nucleatum strains in infected teeth associated with periradicular lesions. Thirteen single-root teeth from adult patients, all having carious lesions, necrotic pulps, and radiographic evidence of periradicular bone loss were included in this study. Combining all methods, the results indicated that F. nucleatum was present in approximately 31% (4 of 13) of the specimens. Incidence of F. nucleatum in root canal infections, as evaluated in this study by polymerase chain reaction, culture, and DNA-DNA hybridization, was 15.4%, 15.4%, and 10.0%, respectively. Our data demonstrated that no method used herein could be considered superior for detecting F. nucleatum directly from clinical samples. However, the small number of samples examined and the low prevalence that was observed should be considered.