The effects of nitric oxide (NO) on cadmium toxicity in Medicago truncatula seedlings were studied by investigating root growth and uptake of antioxidants, IAA and ions. Exposure to cadmium reduced root growth and NO accumulation, and increased the production of reactive oxygen species (ROS) in roots. Supplementation with NO improved root growth and reduced ROS accumulation in roots. The NO-scavenger cPTIO, the nitrate reductase (NR) inhibitor tungstate, and the NO synthase (NOS) inhibitor L-NAME all inhibited the accumulation of NO in roots and reversed the effects of NO in promoting the root growth and accumulation of proline and glutathione. Application of NO reduced auxin degradation by inhibiting the activity of IAA oxidase. Exogenous NO also enhanced the uptake of K + and Ca 2+ . These results suggest that NO improves cadmium tolerance in plants by reducing oxidative damage, maintaining the auxin equilibrium and enhancing ion absorption.

ObjectiveOur primary objective is to phylogenetically characterize the supragingival plaque bacterial microbiome of children prior to eruption of second primary molars by pyrosequencing method for studying etiology of early childhood caries.MethodsSupragingival plaque samples were collected from 10 caries children and 9 caries-free children. Plaque DNA was extracted, used to generate DNA amplicons of the V1–V3 hypervariable region of the bacterial 16S rRNA gene, and subjected to 454-pyrosequencing.ResultsOn average, over 22,000 sequences per sample were generated. High bacterial diversity was noted in the plaque of children with caries [170 operational taxonomical units (OTU) at 3% divergence] and caries-free children (201 OTU at 3% divergence) with no significant difference. A total of 8 phyla, 15 classes, 21 orders, 30 families, 41 genera and 99 species were represented. In addition, five predominant phyla (Firmicute, Fusobacteria, Proteobacteria, Bacteroidetes and Actinobacteria) and seven genera (Leptotrichia, Streptococcus, Actinomyces, Prevotella, Porphyromonas, Neisseria, and Veillonella) constituted a majority of contents of the total microbiota, independent of the presence or absence of caries. Principal Component Analysis (PCA) presented that caries-related genera included Streptococcus and Veillonella; while Leptotrichia, Selenomonas, Fusobacterium, Capnocytophaga and Porphyromonas were more related to the caries-free samples. Neisseria and Prevotella presented approximately in between. In both groups, the degree of shared organism lineages (as defined by species-level OTUs) among individual supragingival plaque microbiomes was minimal.ConclusionOur study represented for the first time using pyrosequencing to elucidate and monitor supragingival plaque bacterial diversity at such young age with second primary molar unerrupted. Distinctions were revealed between caries and caries-free microbiomes in terms of microbial community structure. We observed differences in abundance for several microbial groups between the caries and caries-free host populations, which were consistent with the ecological plaque hypothesis. Our approach and findings could be extended to correlating microbiomic changes after occlusion establishment and caries treatment.

Background/Aim The extra‐alveolar period and storage medium are important for the survival of replanted teeth. The aim of this study was to evaluate factors affecting the survival of replanted teeth in children. Material and Methods Complete dental records of avulsed teeth including age, gender, extra‐alveolar time, storage type and period, stage of root development, crown fracture, gingival laceration, alveolar fracture, antibiotics, and splint type and period were obtained. Kaplan‐Meier, Cox regression and chi‐square tests were used to analyse the risk factors affecting survival (P < 0.05). Results The study included 196 replanted teeth with a mean follow‐up period of 4.0 years. Forty‐two (21.4%), 45 (23.0%), and 109 teeth (55.6%) showed functional healing, inflammatory resorption and replacement resorption. The root resorption incidence of teeth with extra‐alveolar time longer than 30 minutes was higher vs teeth with a time of less than 30 minutes (P = 0.010). Physiologically stored replanted teeth showed lower incidence of root resorption (19/31, 61.3%) than those stored in non‐physiologic media (94/114, 82.5%) (P = 0.025). Root resorption incidence of teeth stored non‐physiologically within 30 minutes and then transferred to physiologic media (25/33, 75.8%) was similar to that of teeth stored physiologically (P = 0.127). Teeth stored non‐physiologically for longer than 30 minutes had a significantly higher root resorption incidence (99/113, 87.6%) than teeth stored non‐physiologically within 30 minutes (55/83, 66.3%) (odds ratio = 1.726, P = 0.001). Pulp canal obliteration occurred in five of the 56 immature teeth (8.9%) but two of them were later extracted because of replacement resorption. The survival of mature teeth (111/140, 79.3%) was significantly higher than that of immature teeth (39/56, 69.6%) (P = 0.007). Conclusions This study suggested that non‐physiologic storage within 30 minutes was critical for the periodontal healing of replanted teeth. Replanted immature teeth had lower survival rates than mature teeth.

As one of the most prevalent human infectious diseases, dental caries results from dysbiosis of the oral microbiota driven by multiple factors. However, most of caries studies were cross-sectional and mainly focused on the differences in the oral microbiota between caries-free (CF) and caries-affected (CA) populations, while little is known about the dynamic shift in microbial composition, and particularly the change in species association pattern during disease transition. Here, we reported a longitudinal study of a 12-month follow-up of a cohort of 3-year-old children. Oral examinations and supragingival plaque collections were carried out at the beginning and every subsequent 6 months, for a total of three time points. All the children were CF at enrollment. Children who developed caries at 6-month follow-up but had not received any dental treatment until the end of the study were incorporated into the CA group. Children who remained CF at the end of the study were incorporated into the CF group. Using Illumina Miseq Sequencing of the 16S rRNA gene, we monitored the shift of supragingival microbiome during caries initiation and progression in children who developed caries over the 12-month study period. Intriguingly, principle coordinates analyses revealed two major shifting patterns in microbial structures during caries initiation and progression in CA group, but not in CF group. Dynamic co-occurring OTU network study showed that compared to CF group, there was significant increase in both number and intensity of correlations between microbial taxa, as well as the formation of tight clusters of specific bacteria in CA group. Furthermore, there were enhanced correlations, positive ones between CA-enriched taxa, and negative ones between CF-enriched and CA-enriched species within CA group. Our data suggested coordinated microbial interactions could be essential to caries pathogenesis. Most importantly, our study indicated that significant microbial shifts occur not only during caries development, but even in the sub-clinical state. Using supragingival microbiome profiles, we were able to construct a caries-onset prediction model with a prediction accuracy of 93.1%. Our study indicated that the microbial shifts prior to the onset of caries might potentially be used for the early diagnosis and prediction of caries.

Existence of concurrent luxation injury and complete root development are important risk factors of pulp necrosis in teeth with uncomplicated crown fractures in adolescent.