Two novel SNPs in genes involved in immune response and their association with mandibular residual ridge resorption.

"Residual ridge resorption" (RRR) is a multifactorial condition involving bone resorption of the residual ridge. We investigated 10 single nucleotide polymorphisms (SNPs) in seven genes with the aim of identifying the genetic factors associated with RRR susceptibility. The study group included 96 RRR patients and 96 controls. Age at first edentulism, duration of edentulism, and bone height were recorded. Saliva was collected from the subjects for DNA extraction. Genotype analysis was performed on the 'SequenomMassARRAYiPLEX'. The genotype and allele frequencies calculated in patients and controls were compared. We found that rs1800896 in the IL10 gene and rs5743289 in NOD2 gene showed significant association with RRR. Within the RRR group, genotypes for each SNP were separated, and we observed that the age at first edentulism and bone height showed variations in the different genotypes of the ten studied SNPs. This study showed an association between SNPs in IL10 and NOD2 genes. It also revealed that the genotypes of the different SNPs influence bone resorption and health. Additionally, age at first edentulism and bone height were much lower in some genotypes. This study demonstrates the need for larger multicenter trials to confirm these findings. Finally, we suggest that the results of this study may be utilized for developing novel genetic diagnostic tests and for identifying Saudi individuals who may be more susceptible to RRR development following dental extraction.

Mandibular residual ridge height in relation to age, gender and duration of edentulism in a Saudi population: A clinical and radiographic study.

PURPOSE: The purpose of this clinical and radiographic study was to evaluate the effect of age, gender and duration of edentulism on the amount of mandibular residual ridge resorption in a Saudi population. MATERIAL AND METHODS: Partially and completely edentulous Saudi patients (50 male and 64 female) attending the outpatient clinics at College of Dentistry, King Saud University, Riyadh, Saudi Arabia were included. Current age, gender of subjects and date of start of edentulism were recorded. Digital panoramic dental radiograph less than 1 year old of each patient was examined. The height of edentulous mandible was measured as described in the American College of Prosthodontists Prosthodontic Diagnostic Index (PDI) classification. Students t-test and ANOVA post hoc tests, Pearson's correlation coefficient (r) and chi square (χ2) analysis were performed as indicated. Level of statistical significance was set at 0.05. RESULTS: Male patients showed a significantly greater mandibular bone height compared to female patients. Age and bone height were statistically significantly negatively correlated (p = 0.0001). However, age and mandibular bone height in only male patients was negatively correlated and reached statistical significance (p = 0.001) A negative correlation was observed between duration of edentulism and mandibular bone height in both genders, but was not statistically significant (p > 0.05). CONCLUSIONS: In a Saudi population, men have greater mandibular bone height than women and also exhibit a negative correlation between age and mandibular bone height that is statistically significant. In contrast, women exhibited a negative correlation between age and mandibular bone height, but was not statistically significant.