There is a correlation between bone mineral density (BMD) and craniofacial morphology. Polymorphisms in the 3' end of the vitamin D receptor (VDR) gene have demonstrated a correlation with the bone mineral density (BMD) of several skeletal sites, but the relation of VDR polymorphisms to craniofacial morphology is not known. In this experiment, the correlation between VDR polymorphisms and 5 linear measurements (cranial base length, N-S; maxillar length, A'-PTM'; mandibular ramus length, CD-GO; mandibular corpus length, GO-POG'; and overall mandibular length, CD-GN) concerning craniofacial morphology was examined in a normal Japanese female population. Genomic DNA as a template was extracted from the blood of each subject, and the VDR polymorphism was determined by polymerase chain reaction-restriction length polymorphism (PCR-RFLP) with three restriction enzymes (BsmI, ApaI, TaqI). Five linear measurements from a lateral cephalogram and body height were also assessed for each subject. Although VDR is known to play important roles in regulating bone growth and BMD, which influence craniofacial morphology, no statistically significant correlation was observed between VDR polymorphisms and 5 linear craniofacial measurements or body height. The polymorphisms of the VDR gene do not play a significant role in determining craniofacial morphology. The strategy of this study would be useful for evaluating a genetic background in craniofacial morphology.
In order to develop an ammonia-free phosphate-bonded investment, Mg (H2PO4) 2 nH2O and MgO were used as a binder. The ratio (wt%) of MgO to Mg (H2PO4) 2·nH2O was designed from 3 to 0.5. Setting time and compressive strength were examined to determine a suitable distribution. A mixture with the ratio of 1.0 and 1.2 showed excellent properties as the binder. The setting time became shorter and compressive strength became lower as the ratio increased. X-ray diffraction appeared MgHPO4·3H2O after setting and Mg2P2O7 after heated at 800°C. These results suggested that Mg (H2PO4) 2·H2O can be applied for dental investments.