In this study, we investigate the influence of the anterior crossbite on the normal pattern of growth and development of the dental arch, when presented in the primary dentition. The results showed that the width of dental arch of anterior crossbite group had tendency to be larger, except in distances Cc-Cc (A-maxilla) and D-D (E-mandible); the length of dental arch in the maxilla had tendency to be narrower; the dental height had tendency to be shorted.
Using the cell-maceration/scanning electron microscope (SEM) method with sodium hydrate (NaOH), the periodontal ligament fibers surrounding rat molars 1-9 weeks after birth were investigated. The specimens, demineralized with 10 % EDTA and cut into small pieces, were variably treated with NaOH concentrations. The hypo-concentration and the short maceration time retained the cellular and fiber elements, whereas the hyper-concentration and the longer maceration time or the higher room temperature damaged the collagen fibrils in the bone, cementum, and dentin; in addition, they caused the periodontal ligament fibers to swell. The suitable conditions of the NaOH concentration and the maceration time on the periodontal ligament surrounded by the mineralized tissues were 5-10 % and 5 days at room temperature of 20-25°C. Under such treatment, the three-dimensional structure of the periodontal ligament fibers was revealed with the SEM, and the arrangement of the fibers was similar to that under the light microscopic observation.
The diaphyses of femurs obtained from crab-eating monkeys (6 months old, 3 years old and about 20 years old) were examined with a high-resolution scanning electron microscope in order to observe three dimensional ultrastructure of the surface matrix of cortical bone. Specimens were treated by trypsin solution to digest both osteoblasts and amorphous organic matrix on the bone surface. The superficial matrix of the immature bone was composed of collagen fibrils with dense reticular structure. Under the sparse reticular collagen fibrils, the collagen fibrils running in a uniform direction were observed. At the surface of mature bone, the collagen fibrils running in a roughly uniform direction to the long axis of the bone were observed and these collagen fibrils formed bundles. Microgranules attaching on the very compact collagen fibrils were found at the surface of mature and senile bone. At the surface of senile bone, the collagen fibrils were almost buried by homogeneous granular bone matrix. It is considered that the microgranules were the calcified granules constructed by crystals of hydroxyapatite.