Genetic evidence for facial variation being a composite phenotype of cranial variation and facial soft tissue thickness

Facial and cranial variation represent a multidimensional set of highly correlated and heritable phenotypes.Little is known about the genetic basis explaining this correlation.We develop a software package ALo SFL for simultaneous localization of facial and cranial landmarks from head computed tomography(CT)images,apply it in the analysis of head CT images of 777 Han Chinese women,and obtain a set of phenotypes representing variation in face,skull and facial soft tissue thickness(FSTT).Association analysis of 301 single nucleotide polymorphisms(SNPs)from 191 distinct genomic loci previously associated with facial variation reveals an unexpected larger number of loci showing significant associations(P<1e-3)with cranial phenotypes than expected under the null(O/E=3.39),suggesting facial and cranial phenotypes share a substantial proportion of genetic components.Adding FSTT to a SNP-only model shows a large impact in explaining facial variance.A gene ontology analysis reveals that bone morphogenesis and osteoblast differentiation likely underlie our cranial-significant findings.Overall,this study simultaneously investigates the genetic effects on both facial and cranial variation of the same sample,supporting that facial variation is a composite phenotype of cranial variation and FSTT.

Measurement of the Elasticity of Biological Soft Tissue of Finite Thickness

Elasticity is of profound significance to evaluating the function of a biological soft tissue. When the elasticity of a tissue is macroscopically changed, it means that the biological function of the tissue is abnormal and some disease or injury may occur. In the present work, an elastometer is developed to measure the elasticity of biological soft tissues. The measurement is based on the indentation method and the force is measured by the bending of the cantilever. The force-indentation data of the soft tissue is experimentally measured by this elastometer and Young＇s modulus of the tissue is calculated using the Hertz-Sneddon model. For comparison, a numerical model for the indentation method is established using the finite element method. The difference between the actual modulus and the measured modulus is discussed. The effect of the thickness of the specimen on the measurement is investigated. Young＇s moduli of beef, porcine liver and porcine kidney are experimentally measured. The results indicate that our elastometer is effective in measuring Young＇s modulus of a soft tissue quantitatively.

Papillae alterations around single-implant restorations in the anterior maxillae:thick versus thin mucosa

To evaluate the papilla alterations around single-implant restorations in the anterior maxillae after crown attachment and to study the influence of soft tissue thickness on the papilla fill alteration. According to the inclusion criteria, 32 patients subjected to implant-supported single-tooth restorations in anterior maxillae were included. The patients were assigned to two groups according to the mucosal thickness： （i） group 1, 1.5 mm≤mucosal thickness≤3 mm; and （ii） group 2, 3 mm〈mucosal thickness≤4.5 mm. Assessments of interproximal papillae at the time of crown placement （baseline） and at 6-month postloading （follow-up） were made by two prosthodontists using papilla fill index （PFI）. The mean mucosal thickness was （2.49±0.31） mm （group 1） and （3.81±0.31） mm （group 2） for the two groups respectively. A significant difference in PFI between the groups was detected at the baseline （P〈O.O01）. PFI improvements over time occurred after 6-month follow-up irrespective of the groups. When compared to group 1, the likelihood to obtain papilla fill was significantly higher for group 2 with an odds ratio of 6.05 （P〈O.O01）. The interproximal papilla level around single-implant restorations could improve significantly over time after 6-month restoration according to PFI assessment. The thicker mucosa before implant placement implied a more favorable esthetic outcome in papilla alteration.