Microbiota of deciduous endodontic infections analysed by MDA and Checkerboard DNA-DNA hybridization.

AIMS: To evaluate the microbiota of endodontic infections in deciduous teeth by Checkerboard DNA-DNA hybridization after uniform amplification of DNA in samples by multiple displacement amplification (MDA). METHODOLOGY: Forty samples from the root canal system of deciduous teeth exhibiting pulp necrosis with or without radiographically detectable periradicular/interradicular bone resorption were collected and 32 were analysed, with three individuals contributing two samples; these were MDA-amplified and analysed by Checkerboard DNA-DNA hybridization for levels of 83 bacterial taxa. Two outcome measures were used: the percentage of teeth colonized by each species and the mean proportion of each bacterial taxon present across all samples. RESULTS: The mean amount of DNA in the samples prior to amplification was 5.2 (±4.7) ng and 6.1 (±2.3) µg after MDA. The mean number of species detected per sample was 19 (±4) (range: 3-66) to the nearest whole number. The most prevalent taxa were Prevotella intermedia (96.9%), Neisseria mucosa (65.6%), Prevotella nigrescens (56.2%) and Tannerella forsythia (56.2%). Aggregatibacter (Haemophilus) aphrophilus and Helicobacter pylori were not detected. P. intermedia (10%), Prevotella tannerae (7%) and Prevotella nigrescens (4.3%) presented the highest mean proportions of the target species averaged across the positive samples. CONCLUSION: Root canals of infected deciduous teeth had a diverse bacterial population. Prevotella sp. were commonly found with P. intermedia, Prevotella tannerae and Prevotella nigrescens amongst the most prominent species detected.

Atraumatic restorative treatment: clinical, ultrastructural and chemical analysis.

With the purpose of checking, in vivo, the effect of atraumatic restorative treatment (ART) on the remaining demineralized dentin, 12 primary molars with deep occlusal lesions from children with ages ranging from 3 to 7 were evaluated. After lesion excavation, and before glass ionomer cement placement, dentin samples were collected from the pulpal wall of the cavity. After 3 months, the restorations were removed and new samples were collected. Six microareas of each sample were analyzed by X-ray energy dispersion spectrometer. Samples obtained before treatment were infected and intertubular dentin had a loosely organized collagen matrix, with well-defined collagen fibers. Following treatment, in addition to a drastic reduction of the amount of bacteria, the intertubular dentin was denser, with more compact and closely packed collagen fibers. An increased calcium concentration was observed in dentin collected after treatment (p < 0.001), suggesting tissue remineralization, but fluoride was not detected. We conclude that ART allows a one-session approach, with the purpose of creating more favorable conditions for the healing process.

First permanent molar: first indicator of dental caries activity in initial mixed dentition.

The objective of the present study was to investigate among children in the initial mixed dentition phase the presence of clinical signs that might eventually function as more sensitive indicators of the development of caries disease, denoted here as caries activity. On this basis, we investigated the relationship between salivary levels of mutans streptococci (MS) and decayed, missing and filled permanent and deciduous tooth surfaces (DMFS and dmfs) using microbiological, clinical and radiographic examinations in 81 schoolchildren aged 7-8 years. Whereas dmfs did not present a positive correlation, DMFS was significantly correlated with salivary MS levels. The first permanent molars of the schoolchildren studied comprised 87.3% of the affected surfaces recorded in the DMFS, suggesting that the development of new lesions was preferentially located on the surfaces of the first permanent molars. These results permit us to conclude that the first permanent molars function as first indicators of dental caries activity in the schoolchildren examined.