Manejo conservativo e microbiota associada à cárie dentinária em dentes permanentes

Abstract

The progression of carious lesions leads to the colonization of dentinal tissue by microorganisms involved in caries disease. Although some microorganisms with S. mutans and lactobacilli have been consistently found in such lesions, the presence of other microorganisms, as well as their interactions, have not yet been fully elucidated. The complete eradication of microorganisms from the dentinal tissue during cavity preparation is not necessary to stop the lesion, given that the driving force for the progression of the lesion is due to the metabolic processes of the biofilm in the presence of fermentable carbohydrates. The present thesis is composed of two chapters and aimed to: present the findings found in a randomized and controlled clinical trial that evaluated the clinical efficacy of selective removal of carious tissue (SRCT) in permanent teeth in relation to the maintenance of pulp sensitivity and quality of restorations (Chapter 1). In addition, to analyze through molecular identification, presence/absence of potentially cariogenic microorganisms in samples of carious dentin from moderate and deep lesions (Chapter 2). In the first study, 74 teeth with carious lesions involving at least 2/3 of the dentin were restored using SRCT or non-selective removal of carious tissue (NSRCT). The loss of pulp sensitivity occurred in only three teeth (1 submitted to SRCT and 2 to NSRCT), in the initial six months. Furthermore, at 12 and 18 months no additional failure associated with loss of pulp sensitivity was observed. There were no significant differences between the experimental groups regarding the occurrence of the outcome. The analysis of the quality of the restorations using the Functional Property criteria of the World Dental Federation was successful, given that no restoration analyzed failed up to 18 months. Thus, SRCT proved to be a less invasive, safe and equally effective treatment when compared to NSRCT. In the molecular identification of microorganisms present in 47 samples of moderate and deep dentin lesions, the presence of the Streptococcus spp., Lactobacillus spp. and Bifidobacterium spp. in 95.7%, 93.6% and 93.6% of the samples evaluated, respectively. Furthermore, high occurrence rates for L. casei group (85.1%), L. rhamnosus (80.9%) and L. acidophilus (68.1%) were observed. Still, L. paracasei was present in 59.6% of the samples. In contrast, S. mutans was absent in most lesions (66%). For the depth of the cavities, there was only difference for the species L. rhamnosus (p=0.010), which was more likely to be present in deep injuries than in moderate depth injuries. Thus, it is suggested that the microorganisms analyzed may be strongly associated with active dentinal lesions, whether of moderate or deep depth. However, S. mutans may be less present in active carious lesions in dentin.