Francisco Montagner

Antimicrobial action of intracanal medicaments on the external root surface

OBJECTIVES To assess in vitro the antimicrobial action of intracanal medicaments in the external root surface, with or without of cementum. METHODS After the placement of intracanal medicaments, the coronal and apical openings were sealed. The antimicrobial action of 2% chlorhexidine gel (2%CHX); calcium hydroxide+2% chlorhexidine gel (CH+2%CHX); calcium hydroxide+2% chlorhexidine gel+zinc oxide (CH+2%CHX+ZnO); calcium hydroxide+saline solution (CH+SS) was evaluated against Enterococcus faecalis, Candida albicans, Actinomyces viscosus and Porphyromonas gingivalis. The samples were placed over the agar, and the zones of inhibition of microbial growth were measured after the incubation period. RESULTS The antimicrobial effects of the medicaments could be ranked from strongest to weakest as follows: 2%CHX, CH+2%CHX, CH+2%CHX+ZnO, CH+SS. No differences among groups were verified in the presence or absence of cementum. CONCLUSIONS 2%CHX containing medicaments diffused into the dentin and reached the outer surface, exerting antimicrobial action.

Frequency, Microbial Interactions, and Antimicrobial Susceptibility of Fusobacterium nucleatum and Fusobacterium necrophorum Isolated from Primary Endodontic Infections

This study assessed the prevalence and microbial interactions of Fusobacterium nucleatum and Fusobacterium necrophorum in primary endodontic infections from a Brazilian population and their antimicrobial susceptibility to some antibiotics by the E-test. One hundred ten samples from infected teeth with periapical pathologies were analyzed by culture methods. Five hundred eighty individual strains were isolated; 81.4% were strict anaerobes. F. nucleatum was found in 38 root canals and was associated with Porphyromonas gingivalis, Prevotella spp., and Eubacterium spp. F. necrophorum was found in 20 root canals and was associated with Peptostreptococcus prevotii. The simultaneous presence of F. nucleatum and F. necrophorum was not related to endodontic symptoms (p > 0.05). They were 100% susceptible to amoxicillin, amoxicillin/clavulanate, and cephaclor. Fusobacterium spp. is frequently isolated from primary-infected root canals of teeth with periapical pathologies. Amoxicillin is a useful antibiotic against F. nucleatum and F. necrophorum in endodontic infections and has been prescribed as the first choice in Brazil.

Molecular Fingerprinting Reveals the Presence of Unique Communities Associated with Paired Samples of Root Canals and Acute Apical Abscesses

INTRODUCTION Acute primary endodontic infections are polymicrobial infections that affect both the root canal (RC) system and apical tissues. It is known that these communities cannot be detected by conventional culturing methods. The aim of this study was to examine the profile of microbial communities in necrotic RCs and acute apical abscesses (AAAs) using an open-ended molecular approach to compare the diversity and composition of the microbiota of these two communities. METHODS Paired samples of RC and PA exudates were collected from 20 subjects and analyzed by terminal restriction fragment length polymorphism (t-RFLP). The number of peaks, the peak areas, and the community diversity were compared between RCs and PAs. The similarity of the microbial profile of each pair of RCs and PAs was assessed by computing the number of shared peaks and the Bray-Curtis Similarity Index. RESULTS A total of 103 and 75.5 unique fragments (t-RFs) were detected in RC and PA samples, respectively. RCs and PAs were not different in the number of species or in the community diversity; however, very few species were shared between RC and PA samples. No single t-RF fragment was detected in all samples, and the majority was detected in only one sample. Low diversity of species was observed in the RCs of smokers. Subjects with previous pain showed fewer species and greater community diversity. CONCLUSION The microbial profiles of the RC and PA communities are distinct and diverged between all subjects, suggesting that acute endodontic infections are microbiologically heterogeneous.

In vitro antifungal action of different substances over microwaved-cured acrylic resins.

Objective: The presence of Candida albicans on the surfaces of denture-base acrylic resins is strongly related to the development of oral stomatitis. This study evaluated the antifungal action of different agents over microwave-cured acrylic resin without polishing specimens previously contaminated with Candida albicans. Material and Methods: Sixty specimens were immersed in BHI broth previously inoculated with the yeast and stored for 3 h at 37°C. They were divided into 5 experimental groups (n=10): G1: 2% chlorhexidine solution (10 min); G2: 0.5% sodium hypochlorite (10 min); G3: modified sodium hypochlorite (10 min); G4: effervescent agent (5 min); G5: hydrogen peroxide 10v (30 min). The specimens of the control group 1 (C1) were not disinfected. Ten additional specimens of the control group 2 (C2) were not infected with the yeast, aiming to check the asepsis during the experiment. The disinfection agents were neutralized and the acrylic resin specimens were immersed in BHI Broth for 24 h. Culture media turbidity was evaluated spectrophotometrically according to the transmittance degree, i.e. the higher the transmittance the stronger the antimicrobial action. Statistical analysis was performed (Kruskal-Wallis Test, p<0.05). Results: The results, represented by the medians, were: G1 = 40; G2 = 100; G3 = 100; G4 = 90; G5 = 100; C1 = 40; C2 = 100. Conclusions: This in vitro study suggested that sodium hypochlorite-based substances and hydrogen peroxide are more efficient disinfectants against C. albicans than 2% chlorhexidine solution and the effervescent agent.

Polarized light microscopic analysis of bone formation after inhibition of cyclooxygenase 1 and 2.

Potassium diclofenac is a potent nonsteroidal anti‐inflammatory drug (NSAID) and COX isoforms (COX‐1 and COX‐2) inhibitor. Quantitative analysis of birefringence with polarized light microscopy is a useful method to investigate the macromolecular orientation and organization of collagen fibers in connective tissues. The aim of this research was to analyze the collagen structure and maturation in bone formed after potassium diclofenac administration, during first molar orthodontic movement. Sixty Wistar rats were divided in two equal groups (N = 30): control (C) and potassium diclofenac (PD). The animals in Group C received 0.9% saline solution and the PD group received potassium diclofenac Cataflam® (5 mg/kg). Animals were sacrificed 3, 7, or 14 days after a NiTi unilateral closed‐coil spring was stretched between the upper right first molar and the incisors. The first molar area was fixed, decalcified, and histologically processed using picrosirius pigment. The collagen birefringence of bone turnover was analyzed by phase retardation. Two‐way ANOVA and Tukeys test showed that optical retardation was influenced by time and treatment. There was increase in the collagen organization over time. On the third day, the C group showed better collagen organization than the PD group. Potassium diclofenac interfered in collagen maturation, reducing fibril organization in the initial phase of orthodontic movement. Anat Rec, 2010.

Gemella morbillorum in primary and secondary/persistent endodontic infections

OBJECTIVE To investigate the presence of Gemella morbillorum by culture or nested PCR in primary and secondary/persistent endodontic infections. STUDY DESIGN Microbial samples were taken from 50 cases with primary and 50 cases with secondary/persistent endodontic infections. Microbiologic techniques were used for culture and identification. The DNA extracted from the samples was analyzed for the presence of the target species using species-specific primers. RESULTS Culture and polymerase chain reaction (PCR) identified the species in 23 and 77, respectively, of 100 root canals. Culture yielded the test organism in 19 of 50 (38%) of root canal samples from primary and in 4 of 50 (8%) from secondary/persistent infections. PCR yielded the test organisms in 41 of 50 (82%) and 36 of 50 (72%) of the, respectively, primary and secondary/persistent root canal infections studied. CONCLUSION Gemella morbillorum was identified more frequently in primary endodontic infections than in secondary/persistent ones. A higher frequency of the target species was detected by PCR than by culture.

An in vitro assessment of type, position and incidence of isthmus in human permanent molars

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure. Objectives This in vitro study assessed the type, position and incidence of isthmus in human permanent molars. Material and Methods One hundred and twenty eight upper and lower first and second permanent molars were analyzed. The roots were embedded in transparent resin, and then split at different distances from the apex (1.0-2.5-4.0-5.5-7.0 mm). Following the sample examination in stereomicroscope, the data were submitted to chi-square statistical test at a 5% significance level. Results The highest isthmus incidence was at 7.0 mm from the root apex in all samples, except the distal root of lower molars (at 5.5 mm). In upper and lower molars, type V (complete isthmus with a continuous opening between the two main root canals) was the most common classification of isthmus (28.8%). In the mesial root of first and second mandibular molars, type IV had the highest incidence (36% and 23.9%, respectively). Conclusion It was concluded that isthmus was widely found in flat roots, with a low percentage in areas close to the apex. In upper and lower molars, these structures were most frequently found at 7 mm from the apex.