Residual microorganisms and/or re-infections are a major cause for root canal therapy failure. Understanding of the bacterial content could improve treatment protocols. Fifty samples from 25 symptomatic and 25 asymptomatic previously root-filled teeth were collected from Sudanese patients with periradicular lesions. Amplified 16S rRNA gene (V1-V2) variable regions were subjected to pyrosequencing (FLX 454) to determine the bacterial profile. Obtained quality-controlled sequences from forty samples were classified into 741 operational taxonomic units (OTUs) at 3% dissimilarity, 525 at 5% dissimilarity and 297 at 10% dissimilarity, approximately corresponding to species-, genus- and class levels. The most abundant phyla were: Firmicutes (29.9%), Proteobacteria (26.1%), Actinobacteria (22.72%), Bacteroidetes (13.31%) and Fusobacteria (4.55%). Symptomatic patients had more Firmicutes and Fusobacteria than asymptomatic patients, while asymptomatic patients showed more Proteobacteria and Actinobacteria. Interaction of disease status and age was observed by two-way ANOSIM. Canonical correspondence analysis for age, tooth restoration and disease status showed a correlation of disease status with the composition and prevalence of different members of the microbial community. The pyrosequencing analysis revealed a distinctly higher diversity of the microbiota compared to earlier reports. The comparison of symptomatic and asymptomatic patients showed a clear association of the composition of the bacterial community with the presence and absence of symptoms in conjunction with the patients’ age.

The effect of nutrition on the timing of human tooth formation is poorly understood. Delays and advancements in dental maturation have all been reported as well as no effect. We investigated the effect of severe malnutrition on the timing of human tooth formation in a large representative sample of North Sudanese children. The sample (1102 males, 1013 females) consisted of stratified randomly selected healthy individuals in Khartoum, Sudan, aged 2-22 years using a cross-sectional design following the STROBE statement. Nutritional status was defined using WHO criteria of height and weight. Body mass index Z-scores and height for age Z-scores of ≤−2 (cut-off) were used to identify the malnourished group (N = 474) while the normal was defined by Z-scores of ≥0 (N = 799). Clinical and radiographic examination of individuals, with known ages of birth was performed including height and weight measurements. Mandibular left permanent teeth were assessed using eight crown and seven root established tooth formation stages. Mean age at entry and mean age within tooth stages were calculated for each available tooth stage in each group and compared using a t-test. Results show the mean age at entry and mean age within tooth stages were not significantly different between groups affected by severe malnutrition and normal children (p>0.05). This remarkable finding was evident across the span of dental development. We demonstrate that there is little measurable effect of sustained malnutrition on the average timing of tooth formation. This noteworthy finding supports the notion that teeth have substantial biological stability and are insulated from extreme nutritional conditions compared to other maturing body systems.

Despite the high success rates of preformed metal crowns (PMCs) in children no randomized clinical trials compare methods of placement and none describe its use in Africa. Our aim was to compare survival and cost-effectiveness of PMCs placed by conventional techniques (CT) and biological Hall techniques (HT) using a prospective randomized control trial in a general dental practice from Khartoum. One hundred and nine and 103 PMCs were placed in randomly selected children (5-8years) with 1–2 carious primary molars using HT and CT respectively and followed for 2 years. Socioeconomic status, periodontal health, occlusion, anxiety, and procedure time were compared using student t-test. Kaplan–Meier survival rates and incremental cost effectiveness ratio (ICER) were compared between CT and HT. CT and HT groups were similar for age, gender, socio-economic status. Survival rates were high (over 90%) for both study arms and not statistically different (p>0.05). Anxiety scores were significantly higher in CT arm after 12 months compared to HT (p<0.001). Clinically, gingival and plaque indices were similar between groups (p>0.05) but occlusions were raised in nearly all subjects in the HT arm (p<0.05). Periodontal health improved, and occlusions adjusted over time in both arms. There were 3 (2.7%) and 6 (5.8%) minor failures, 7 (6.4%) and 6 (5.8%) major failures in HT and CT arms respectively. Mean procedure time was lower in HT (9.1 min) than CT (33.9 min); p<0.001. Mean PMC cost was US$2.45 and US$7.81 for HT and CT respectively. The ICER was US$136.56 more for each PMC placed by CT per life year. We show that PMCs have high survival outcomes in disadvantaged populations similar to results from developed countries. As HT can be carried out by less experienced dental operators and therapists, this biological approach provides a promising cost-effective option to manage caries in developing countries with limited resources. Trial registration: The trial is registered at clinicaltrials.gov. ClinicalTrial.gov Trial Registration: NCT03640013

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