The aim of this study was to compare the percentage of non-instrumented area of root canals prepared with different enlargements using single-file reciprocating systems (Reciproc and WaveOne) and a conventional multi-file rotary (BioRaCe) system by microcomputed tomographic analysis. Thirty mesial roots of mandibular molars with moderate curvature (10° to 20°) presenting a type II Vertucci canal configuration and similar internal volume were chosen and scanned at an isotropic resolution of 14.16 µm. The sample was assigned to 3 groups (n=10) according to the system used for root canal preparation: Reciproc, WaveOne, and BioRaCe groups. Second and third scans were taken after the canals were prepared with instruments sizes 25 and 40, respectively. The recorded images of the surface area voxels of the canals, before and after preparation were examined from the furcation level to the apex to quantify the non-instrumented surface. Statistical data were compared using GLM for repeated-measures with a significance level set at 5%. Instrumentation systems did not influence the percentage of untouched root canal surfaces (p=0.690) whilst a significant reduction in the percentage of static voxels was observed after the enlargement of the root canal (p=0.010) in all groups (p=0.507). None of the systems was able to prepare the entire surface area of the mesial root canal of mandibular molars. The increased final apical size resulted in a significant positive effect on the shaping ability of the tested systems. a l u a t i o n o f N o ni n s t r u m e n t e d C a n a l A r e a s w i t h D i f f e r e n t E n l a r g e m e n t s P e r f o r m e d b y N i T i S y s t e m s M i c r o -C T E v

This study aimed to evaluate the cause-effect relationship between canal preparation with ProTaper Universal (PTU) system and dentinal defects formation using micro-computed tomography (micro-CT) analysis. Forty mesial canals of mandibular molars with a type II Vertucci's canal configuration were scanned at an isotropic resolution of 14.16 µm. The sample was assigned to an experimental (n = 30) and a control (n = 10) groups, and the mesial canals were prepared with PTU system up to F2 instrument. The specimens from the experimental group were scanned and the cross-section images of the mesial roots, before and after preparation, were screened to identify the presence of dentinal defects. In the control group, the specimens were sectioned perpendicularly to the long axis of the root into 1-mm-thick slices (n = 80) and examined under optical microscope. Once a dentinal defect was detected, the slice was scanned through micro-CT. In the experimental group, dentinal micro-cracks were observed in 4,828 slices (24.04%). In all cross-section images, dentinal defects identified in the postoperative images were already present in the corresponding preoperative image. In the control group, 13 out of 80 slices (16.25%) had at least one dentinal defect visualized under stereomicroscopy, which was identified after a further micro-CT scanning. Micro-CT showed reliability as similar as optical microscopy in detecting dentinal defects, adding the possibility of tracking the dentinal tissue, before and after canal preparation, and providing a clear visualization of micro-cracks. Root canal preparation with PTU system did not induce the formation of new dentinal defects.

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Abstract:The purpose of this study was to assess the ability of an off-centered rectangular design system [ProTaper Next (PTN)] to maintain the original profile of the root canal anatomy. To this end, ProTaper Universal (PTU), Reciproc (R) and WaveOne (WO) systems were used as reference techniques for comparison. Forty clear resin blocks with simulated curved root canals were randomly assigned to 4 groups (n = 10) according to the instrumentation system used: PTN, PTU, R and WO. Color stereomicroscopic images of each block were taken before and after instrumentation. All image processing and data analysis were performed with an open source program (Fiji v.1.47n). Evaluation of canal transportation was obtained for two independent regions: straight and curved portions. Univariate analysis of variance and Tukey's Honestly Significant Difference test were performed, and a cut-off for significance was set at α = 5%. Instrumentation systems significantly influenced canal transportation (p = 0.000). Overall, R induced significantly lower canal transportation compared with WO, PTN and PTU (p = 0.000). The curved portion displayed superior canal transportation compared to the straight one (p = 0.000). The significance of the difference among instrumentation systems varied according to the canal level evaluated (p = 0.000). In its straight portion, R and WO exhibited significantly lower transportation than PTN; whereas in the curved portion, R produced the lowest deviation. PTU exhibited the highest canal transportation at both levels. It can be concluded that PTN produced less canal transportation than PTU and WO; however, R exhibited better centering ability than PTN.

The aim of the present study was to compare the porosity characteristics of AH Plus Jet(tm) syringe-mix and the conventional hand-mixed AH Plus root canal sealers by three-dimensional quantitative high-resolution micro-computed tomography (micro-CT). Seven test specimens were prepared from each tested sealer by a single operator following the manufacturer's instructions and poured into pre-lubricated plastic split-ring moulds. Set sealer test specimens were scanned using a micro-CT device and the shadow images were reconstructed into cross-sectional slices. The evaluated parameters were (i) total pore count, (ii) total pore volume and mean pore volume, (iii) total porosity (% of pore volume in relation to total sealer volume) and (iv) mean pore distance to the sealer lateral external surface. In both groups, most pores were localized within the external sealer perimeter (0.05 mm from the external surface). Hand-mixed AH Plus specimens showed statistically significant higher mean total pore count, total pore volume and total porosity (p=0.001) than the syringe-mixed specimens. However, mean pore sizes in AH Plus syringe-mixed specimens were significantly higher (p=0.046) than the AH Plus hand-mixed counterparts. Hand-mixed AH Plus was associated with higher total mean pore count, volume and total porosity compared to syringe mixed AH Plus.

Aim: This in vivo experimental study investigated bacterial microbiome and metabolome longitudinal changes associated with enamel caries lesion progression and arrest. Methods: We induced natural caries activity in three caries-free volunteers prior to four premolar extractions for orthodontic reasons. The experimental model included placement of a modified orthodontic band on smooth surfaces and a mesh on occlusal surfaces. We applied the cariesinducing protocol for 4-and 6-weeks, and subsequently promoted caries lesion arrest via a 2week toothbrushing period. Lesions were verified clinically and quantitated via micro-CT enamel density measurements. The biofilm microbial composition was determined via 16S rRNA gene Illumina sequencing and NMR spectrometry was used for metabolomics. Results: Biofilm maturation and caries lesion progression were characterized by an increase in Gram-negative anaerobes, including Veillonella and Prevotella. Streptococcus was associated caries lesion progression, while a more equal distribution of Streptococcus, Bifidobacterium, Atopobium, Prevotella, Veillonella, and Saccharibacteria (TM7) characterized arrest. Lactate, acetate, pyruvate, alanine, valine, and sugars were more abundant in mature biofilms compared to newly formed biofilms. Conclusions: These longitudinal bacterial microbiome and metabolome results provide novel mechanistic insights into the role of the biofilm in caries progression and arrest and offer promising candidate biomarkers for validation in future studies.

ABSTRACT:The aim of this study was to investigate, in vitro, the morphological characteristics of demineralized primary enamel subjected to brushing with a dentifrice with or without fluoride. In order to do so, 32 enamel blocks were divided in 4 different groups containing 8 blocks each. They were separately immersed in artificial saliva for 15 days. The experimental groups were: C -control; E -submitted to etching with 37% phosphoric acid gel (30 s); EB -submitted to etching and brushing 3 times a day with a non-fluoridated dentifrice; EBF = submitted to etching and brushing 3 times a day with a fluoridated dentifrice. The toothbrushing force was standardized at 0.2 kgf and 15 double strokes were performed on each block. After the experimental period, the samples were prepared and examined under SEM. The control group (C) showed a smooth surface, presenting scratches caused by habitual toothbrushing. The etched samples (E) exhibited different degrees of surface disintegration, but the pattern of acid etching was predominantly the type II dissolution. The brushed surfaces were smooth, with elevations which corresponded to the exposure of Tomes' process pits and depressions which corresponded to interrod enamel. Particles resembling calcium carbonate were found in the most protected parts of the grooves. No morphological differences were observed between brushing with fluoridated (EBF) and non-fluoridated (EB) dentifrice. The results suggest that the mechanical abrasion caused by brushing demineralized enamel with dentifrice smoothes the rough etched surface, and the presence of fluoride does not cause morphological modifications in this pattern. UNITERMS: Tooth, deciduous; Dental enamel/ultrastructure; Tooth demineralization. RESUMO:O objetivo do estudo foi investigar as características morfológicas do esmalte decíduo desmineralizado submetido à escovação com dentifrício fluoretado ou não fluoretado. Para isto, 32 blocos de esmalte foram separados em 4 grupos diferentes, contendo 8 elementos cada que foram imersos em saliva artificial por 15 dias: C = controle; E = atacado com gel de ácido fosfórico a 37% por 30 segundos; EB = atacado e escovado 3 vezes ao dia com dentifrício não fluoretado; EBF = atacado e escovado 3 vezes ao dia com dentifrício fluoretado. A escovação foi padronizada em 0,2 kgf e 15 movimentos de vai-e-vem foram executados em cada bloco. Após o período experimental, as amostras foram preparadas e examinadas no MEV. O grupo controle (C) apresentou lisura superficial e riscos causados pela escovação habitual; as amostras atacadas (E) apresentaram diferentes graus de desintegração superficial, porém o padrão de ataque ácido foi predominantemente a dissolução do tipo II. As superfícies escovadas apresentaram-se alisadas, com exposição das elevações correspondentes aos processos de Tomes e as depressões de esmalte interprismático. Partícu-las semelhantes a carbonato de cálcio foram encontradas nas partes mais protegidas das depressões. Não houve diferença quando os grupos foram escovados com denti...