Development of the tooth is a complex and fascinating set of processes which require a sequential integration of numerous biological steps. For dental doctors, interest is particularly high, because the tooth is mainly composed of surface ectodermal epithelium and neural crest derived neuroectodermal mesenchyma, and formed by epithelial-mesenchymal interactions. There are many different types of odontogenic neoplasms. In general, proliferation, development and cytological differentiation of the neoplastic cells reflect the normal physiological development of the outbreak mother cells and/or tissues. There would appear to be a relationship between the cytological differentiation of odontogenic neoplastic cells and the physiological development and differentiation of tooth germ. We describe some morphogenesis regulation factors, such as Notch signaling, in the odontogenic neoplastic cells, in both well-differentiated and poorly-differentiated neoplasms. Our results suggest that these factors play some role in cytological differentiation or acquisition of tissue-specific characteristics in neoplastic cells.

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Many model analyses methods for measuring tooth size discrepancies, even though they are not always used have been carried out by many authors and formulated for the predetermination of arch size. On the basis of their findings many studies were carried out to find out its reliability, few researchers agreed to the statement made and few pointed out their lack of agreement. Bolton’s method of diagnosing tooth-size discrepancy has been widely used in scientific studies since its publication. Cast analysis is required for all potential orthodontic patients, whether problems are moderate or severe. It is done to evaluate symmetry, alignment (crowding, spacing) and tooth size analysis.

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A newly developed titanium alloy, Ti-15%Zr-4%Nb-4%Ta (Ti15Zr4Nb4Ta), has been shown to have excellent mechanical characteristics, corrosion fatigue strength, anticorrosion, cytocompatibility, and biocompatibility. The purpose of this study was to compare the bone mineral density (BMD) and area of newly formed bone around Ti15Zr4Nb4Ta implants to that around Ti-6%Al-4%V alloy (Ti6Al4V) implants. We inserted 2 types of implants (surface treat of the machine and the blast implant) in New Zealand white rabbit femurs under general anesthesia. The rabbit was done perfusion fixation of 4, 8, 16, 24, and 48 weeks later, and the femurs with the implants were collected and we observed the surrounding bone by an implant drawing test. We measured the BMD and the area of the newly formed bone surrounding the implant inserted part using image analysis software Image-Pro PLUS Ver. 4.0^® which it developed newly in micro focus computed tomography (micro CT). The results showed the machine and the blast implant together, which the BMD and area around the Ti15Zr4Nb4Ta implants were comparable to or greater than those around the Ti6Al4V implants. These results suggested that the new alloy, Ti15Zr4Nb4Ta, might be useful for orthopedic or dental implants with the added advantage of superior biologic safety and mechanical properties than the current alloy, Ti6Al4V.

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The purpose of this study is to develop a three-dimensional method of caries evaluation; once a method is established genetic variables can be altered in order to detect the gene(s) involved in the development of dental caries in mice. As dental caries has a three-dimensional nature to its course, the Micro-CT scan quantifies the volume of caries. Inbred Mice were used of known caries susceptibility —BALB/c mice. Mice were divided into the control and experimental group; later inoculated with Streptococcus mutans. The experimental group was fed a caries promoting diet and later caries volume was evaluated by use of the Micro-CT scan in both groups. There was a clear difference in tooth volume of mice infected for 7 weeks and 9 weeks, the Micro-CT scan indicated this evidently.

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Abstract:In the current study, we compared the recently developed CaTiO₃-amorphous carbon (CaTiO₃-aC) as a bone inducing coating material with HA from aspects of surface electric charge and solubility. CaTiO₃-aC had negative surface electric charge similar to HA. Thus similar tissue reaction and bone inducing ability were considered to obtain. On the other hand solubility of CaTiO₃-aC coating was lower than HA. Moreover though CaTiO₃-aC itself showed low solubility, CaCO₃ was found to be included in it, and long-term slow Ca²⁺ release occurred. Thus the sample was suggested to be used as an ion exchange material. When the implant using Ti/CaTiO₃-aC/HA double layer coating was developed, first bioactive state of the implant will continue due to HA character. Then even early resorption of HA occurs, bioactive state will continue due to CaTiO₃-aC layer. Therefore Ti base will not expose. This result is supposed to contribute long term success of the implant.

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The aim of this study was to examine whether human gingival fibroblasts (HGFs) sustain to produce prostaglandin E₂ (PGE₂) in the presence of lipopolysaccharide (LPS). HGFs were treated with or without 10 ng/ml of LPS from Porphyromonas gingivalis (PgLPS) for 7 days collecting the culture supernatants for every 24 h, and PGE₂ concentration in the supernatants was measured by ELISA. HGFs produced PGE₂ at low level without PgLPS treatment. In contrast, HGFs continuously produce PGE₂ with PgLPS treatment. At each day, the amount of PGE₂ production by HGFs with PgLPS treatment was higher than that without treatment. These results demonstrate that the characteristic of HGFs, which continuously produce PGE₂ in the presence of LPS, sustains inflammatory response in periodontal disease.

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Rheumatoid arthritis (RA) is a complex disease including autoimmune disorder and resulting in inflammation. It also shows progressive proliferation of synoviocytes, and these synoviocytes destroys articular structure. In order to understand the mechanism of this abnormal proliferation of RA-originated synoviocytes in molecular level, we analyzed the gene expression profiles by using DNA chips that contain more than 10,000 genes. Comparing the expression profiles of normal and RA-originated synoviocytes, we found several genes that are highly expressed in RA-originated synoviocytes than normal synoviocytes. Among these genes, we focused on one hypothetical protein, cDNA of which contains one reading frame in its DNA fragment, indicating that this fragment is a part of large mRNA structure. The expression of this gene in RA-originated synoviocytes is about three times higher than that in normal synoviocytes by DNA chip analysis. After cDNA cloning of this mRNA, we found that the gene is identical with lumican, which encodes a collagen binding, extracellular matrix protein. This mRNA was widely distributed in many tissues but its alternatively spliced forms are differently expressed in various tissues.

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Recently, dental implants have gained much attention for a great number of researchers in dental application. Until now, there are few reports about the properties and metabolism related to the bite force response of the newly bone formed surrounding the implants, which is poorly understood. For that reason, the purpose of this study was to elucidate the new bone formation surrounding the implants and its process of maturation by Micro-CT, polarizing microscope and FTIR analysis. Thus, the implants were inserted in the tibia of rabbits. After 4 and 8 weeks of surgical procedure, three-dimensional image of the implant and bone of non-decalcified samples was observed by Micro-CT analysis; bone structure and its maturity were seen by polarizing microscope; and finally, the PO₄^3-, CCO₃^2- and Amide I elements included in the interface bone-implant and in the new bone during the course time were examined by FTIR analysis. The results of this study, analyzed by this 3 methods, demonstrated that: 1) It was observed a qualitative difference in the new bone formation and the existing bone at 4 and 8 weeks of implantation; 2) There was also a qualitative difference in the newly bone formed at 4 and 8 weeks; 3) The maturation of the new bone started from the exhibiting bone; and 4) None of the methods used in current study destroyed the samples, and reproducibility results were obtained. In conclusion, we suggest a possible qualitative evaluation of new bone formation surroundings the Ti implant.

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