Extracted human deciduous teeth undergoing physiological root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM) and analytical transmission electron microscopy, as well as acid trimetaphosphatase cytochemistry. The granulated tissues, which are rich in multinucleated odontoclasts and capillary vessels, formed various resorption lacunae on the resorbing dentin surfaces. SEM observations of dentin surfaces treated with sodium hypochlorite revealed two types of resorption lacunae: deep, round lacunae in which the peritubular matrix of dentinal tubules was strongly dissolved; and shallow, irregular lacunae with intact peritubular matrix. In trypsin-treated materials, the resorption surfaces were characterized by the presence of numerous collagen fibers in both the peritubular and intertubular matrices, suggesting demineralization of the surface dentin. Odontoclasts were characterized by the presence of abundant mitochondria, perinuclear stacks of Golgi membranes, various lysosomes, numerous endocytotic vacuoles, and a well-developed ruffled border against the resorption lacunae. Most endocytotic vacuoles were distributed in the cytoplasm between the ruffled border and the nuclei. In undemineralized ultrathin sections, the surface dentin of resorption lacunae consisted of collagen fibers and apatite crystals and had a lower packing density than those in unresorbed, deeper dentin. Many apatite crystals were demonstrated to be present in the extracellular channels of the ruffled border and in adjacent endocytotic vacuoles derived from it. Lysosomes located in the perinuclear cytoplasm of odontoclasts contained amorphous dense material and/or a small amount of crystals. An energy-dispersive x-ray microanalysis of apatite crystals in undemineralized sections indicated that the energy spectrum peaks of Ca and P detected from crystals in resorbing dentin were much lower than those in unresorbed dentin. Similarly, lower spectrum peaks of Ca and P were obtained from crystals found in the ruffled border and endocytotic vacuoles of odontoclasts. A slight trace Ca peak also was detected in the amorphous dense material in lysosomes of odontoclasts. The enzyme cytochemistry of lysosomal acid trimetaphosphatase indicated that odontoclasts had intense enzymatic activity in the Golgi membranes, endoplasmic reticulum cisternae, lysosomes, and endocytotic vacuoles. Dense reaction precipitates of enzymatic activity also were found along the dentin surfaces of resorption lacunae occupied by odontoclast ruffled borders.(ABSTRACT TRUNCATED AT 400 WORDS)

Although there have been several studies of finite element method (FEM) analysis on two dimensional (2D) facial growth with cephalometric X-rays, there has been little FEM analysis on three dimensional (3D) facial growth of long term observation. Therefore the objective of our study is to use FEM model by 3D surface measurement of rapid laser device from human dried skull and to analyze the changes of facial growth based on FEM by the volume and the direction of strain in each stage. Samples were taken from each human dried skull for 5 stages; about 0, 3, 6, 9, 12 and 18 years of age, a total of 6 normal human dried skulls. (No abnormal skeletal growth patterns were selected and age was supposed by tooth development and eruption.) After measuring each human dried skull by 3D rapid device, we selected the clearest 16 anatomical reference points from about 70,000 points on face image to form accurate FEM shells. The study utilized Cosmos/M (SRAC) for FEM analysis, on a PC(NEC). From the strain analyses, it was revealed that (1) The vale of growth strain from 0 to 3 years of age and from 3 to 6 years of age gradually increased from condylar area toward mental area and the most vale of growth strain was showed at mental area. The vale of growth strain of corpus area was bigger than other areas. (2) As a whole the vale of growth strain of other areas except mental, corpus and nasal area were almost equal. The results indicate especially the growth change of mandible were predominantly showed in the early stages, and the direction of growth strain changed backward and above from mental area to condylar area.

Soft tissue changes following correction of mandibular hyperplasia were studied using a laser system for three-dimensional (3-D) surface measurement. Twelve subjects (7 men and 5 women; age 17-48 years) were included in this study. Bilateral sagittal split ramus osteotomies were performed in ten patients and intraoral vertical ramus osteotomies in two patients. Pre- and postoperative images, obtained with the laser system, were superimposed to determine distribution of changes in the perioral soft tissue. Mean volume changes were 1032.3 mm3 in the Subnasale-UL area and 8700.9 mm3 in the LL-Menton area. Changes in both areas were symmetrical around the mid-sagittal plane in some patients and asymmetrical in others. This measurement system provided a simple method of determining 3-D changes in soft tissue following surgery and might be useful for clinical purposes.

Soft tissue changes following correction of mandibular hyperplasia were studied using a laser system for three-dimensional (3-D) surface measurement. Twelve subjects (7 men and 5 women; age 17-48 years) were included in this study. Bilateral sagittal split ramus osteotomies were performed in ten patients and intraoral vertical ramus osteotomies in two patients. Pre- and postoperative images, obtained with the laser system, were superimposed to determine distribution of changes in the perioral soft tissue. Mean volume changes were 1032.3 mm3 in the Subnasale-UL area and 8700.9 mm3 in the LL-Menton area. Changes in both areas were symmetrical around the mid-sagittal plane in some patients and asymmetrical in others. This measurement system provided a simple method of determining 3-D changes in soft tissue following surgery and might be useful for clinical purposes.

Abstract:The author examined the ultrastructure and acid phosphatase activity of odontoclasts in physiological root resorption of human deciduous teeth. Extracted teeth undergoing resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for scanning (SEM)-and analytical transmission-electron microscopy (STEM). In SEM observation of resorbing dentine surfaces treated with NaOCl, the peritubular matrices were strongly dissolved resulting in the enlargement of dentinal tubules. The multinucleated giant cells, odontoclasts, were characterized by an abundant mitochondoria, Golgi complexes, many lysosomes, endocytotic vacuoles, and well-developed ruffled borders against the resorption lacunae. The odontoclasts located in resorption lacunae contained numerous small fragments of dentine crystals in endocytotic vacuoles and extracellular canals of ruffled borders. A STEM analysis confirmed remarkably lower energy spectrum peaks of Ca and P in crystal fragments in these endocytotic vacuoles than those in unresorbed dentine matrix.The resorbing dentine surfaces consisted of alternative two electron-dense and two electron-lucent layers:these dense and lucent layers showed lower Ca and P peaks than those from unresorbed dentine. Lysosomal acid phosphatase activity was further demonstrated in the Golgi complex, dark lysosomes, and some endocytotic vacuoles of odontoclasts. These results suggest that odontoclasts are responsible for decalcification of dentine crystals at resorbing dentine surfaces and subsequent resorption and digestion of mobilized crystals.