Anatomical variations and bilateral symmetry of roots and root canal system of mandibular first permanent molars in Saudi Arabian population utilizing cone- beam computed tomography

Aim: The aim of the study was to evaluate the anatomical variations of the roots and root canal system, and to determine the symmetry between right and left sides of mandibular first permanent molars in Saudi Arabian population using images derived from cone beam computed tomography (CBCT) scans. Methods: The CBCT scans (with the following parameters: FOV 170 × 120 mm, 90 Kv, 5–8 mA, 17.5 s exposure time and 0.25 mm voxel size) were retrieved from the database and axial, coronal and sagittal sections of mandibular first molars were examined. The number of roots, canals and type of canal configuration based on Vertucci's classification were recorded. Bilateral symmetry between right and left side of the same individuals and differences between genders were investigated. Results: Out of 174 mandibular first molars, 97.1% were two rooted and 2.9% were three rooted (distolingual root). In regards to the number of canals, 73% had three, 25.3% had four and 1.7% had two root canals. In teeth with four root canals, 90.9% of the extra canal was in the distal root, while 9.1% in the extra distolingual root. The most common canal configuration in mesial and distal root were type IV (64.9%) and type I (77%), respectively. Symmetrical analysis revealed 100% symmetry in number of roots and 56.4% in number of canals between right and left teeth in the same individual. Conclusions: Within the limitation of this study, wide range of canals configurations were noted in mandibular first molars among the Saudi Arabian population. The prevalence of three rooted mandibular first molars was relatively low. Three canals were most commonly seen in mandibular first molars. Bilateral symmetry was varied in number of canals and canals configurations, which could be of clinical significance while performing root canal treatment on both side mandibular first permanent molars

Genetic Diversity and Population Structure of Saudi Arabia

Saudi Arabia is the largest country in the Arabian Peninsula, yet its genetic diversity and population structure has been little studied. This project has used analysis of forensic DNA markers, typed both conventionally (by capillary electrophoresis, CE) and by massively parallel sequencing (MPS), to characterise its genetic diversity. Ychromosomal haplotypes based on 27 STRs (short tandem repeats) were generated in 597 unrelated Saudi males, classified into five geographical sub-regions. This showed marked population structure with low diversity in the Central and Northern regions, and high diversity in the East and West. Haplogroup J1 was very predominant and showed signals of recent expansion. Comparing geographically-matched males recruited in the UK with those recruited in Saudi Arabia showed significant haplotype differences, pointing to social structure. Variation in 21 autosomal STRs was also investigated. As in the Y chromosome study, this revealed population structure, but with a different geographical pattern. Heterozygote deficiency was observed at nearly all loci, probably as a consequence of high levels of consanguineous marriage. MPS analysis (via the Verogen ForenSeq™ DNA Signature Prep Kit) of 27 autosomal STRs and 91 identity-informative single nucleotide polymorphisms (iiSNPs) revealed sequence variation that reduced both the STR-based and iiSNP-based random match probabilities. As with the autosomal CE data, evidence of consanguinity was apparent from both marker types. A global comparison showed that the Saudi sample was typical of Middle Eastern populations, with higher inbreeding than is seen in most European, African and Central/South Asian populations. Y-STR and X-STR sequence data from the same experiments revealed sequence variation in both types of markers. A population-level comparison of the Saudi Arabian X-STRs with a global sample demonstrated affinity with other Middle Eastern populations. This study has revealed population structure and the influence of consanguinity in Saudi Arabia, and provides valuable reference datasets for forensic analysis.</div