The odontoma is a hamartomatous lesion consisting of enamel, dentin, pul and cementum. They are observed in the form of a tooth or as a mass of agglomerated teeth. Most of these occur during the period of development of normal teeth and grow to some extent. The fused tooth was the developmental abnormality of the teeth and the hard tissues of the adjacent teeth were combined. In general, these two lesions are not related, but two problems can occur together with systemic or local causes in the morphological differentiation period. We report a case of a 6 - year - old boy who visited our clinic for the eruption of a calcified mass in the mouth. The patient was diagnosed by the fusion of a odontoma and a mandibular permanent anterior tooth. And then, fused odontoma was removed surgically and the mandibular permanent anterior was restored by using composite resin. Calcified material was diagnosed as a composite tooth. After 6 months, the permannant teeth was satisfactory eruption and did not show any pathological problems in periapical radiography.

Recently, car pump market is positively growing in emerging countries as well as advanced countries. A increasing attention is recently drawn to electric vehicle but, still commercialization is expected to take a long time. This research is to study on the performance analysis for change in number of teeth of internal gear oil pump with three different numbers of teeth in the inner gear. After measuring real design features, modeling, velocity distribution and pressure distribution are conducted numerically. Pressure changes and volumetric efficiencies are compared with three different cases in order to analyze the performance for inner gears. Finally, optimum volumetric efficiency is determined with the sequence of case 1, case 2, and case 3.

Dental brackets are widely used by the orthodontists to correct the misalignment of teeth in the mouth over a long period of time. In this study, finite element analysis of orthodontic bracket has been carried out for the observation of the stress distribution and deformation pattern in the different materials bracket (Stainless Steel, Ceramic, Titanium, Polycarbonate and Nitinol) when subjected to arch wire torsion and tipping force. The simulation results were further optimized with respect to bracket attachment surface. It was found that it is possible to know the change in result is correlated with the attachment surface of the stress and deformation due to change in diameter. The results confirmed that the finite element method has proved to be successful for proper design analysis for future development of the teeth bracket.

Orthodontic is important to apply the optimal orthodontic force. The orthodontic bracket is deformed and the stress caused by tension and torsion of the wire. In this study, using the ANSYS the material that is currently widely used in orthodontic bracket material of stainless steel, ceramic, titanium, polycarbonate, by applying the nitinol analyzed the strain and the stress distribution on the bracket side. Simulation results on the stress distribution and deformation, and it was found a difference of each material.

A method is developed to simulate the fatigue crack growth in a carburized gear tooth considering the effect of residual stress. The calculation of stress intensity factor and the fatigue crack growth rates in the case layer are estimated by the experimental formula obtained in this study. The crack growth of carburized gears is measured by a crack gauge, and the validity of the simulation is confirmed. The critical length of initial crack which corresponds to the fatigue strength is introduced in the method, and a new design procedure of carburized gears is proposed based on the critical length of crack. As an example of the application of the procedure, the size effect is tried to discuss.

Human dental pulp stem cells (DPSCs) are multi-potent mesenchymal stem cells that have several differentiation potentials. An understanding of thetissues that differentiate from these cells can provide insights for future regenerative therapeutics and tissue engineering strategies. The mesiodens is the most frequent form of supernumerary tooth from which DPSCs can differentiate into several lineages similar to cells from normal deciduous teeth. Recently, it has been shown that nanoscale structures can affect stem cell differentiation. In our presentstudy, we investigated the effects of a 250-nm nanoscale ridge/groove pattern array on the osteogenic and adipogenic differentiation of dental pulp cells from mesiodenscontaining human DPSCs. To this end, the expression of lineage specific markers after differentiation induction was analyzed by lineage specific staining and RT-PCR. The nanoscale pattern arrayed surface showed apositive effect on the adipogenic differentiation of DPSCs. There was no difference between nanoscale pattern arrayed surface and conventional surface groups onosteogenic differentiation. In conclusion, the nanoscale ridge/groove pattern arrayed surface can be used to enhance the adipogenic differentiation of DPSCs derived from mesiodens. This finding provides an improved understanding of the effects of topography on cell differentiation as well as the potential use of supernumerary tooth in regenerative dental medicine.

The working mechanism of bisphosphonate on bone cells is unclear despite its powerful inhibitory activity on bone resorption. The differentiation and activation of osteoclasts are essential for bone resorption and are controlled by the stimulatory RANKL and inhibitory OPG molecules. Teeth exhibit a range of movement patterns during their eruption to establish their form and function, which inevitably accompanies peripheral bone resorption. Hence, the mandible, which contains the teeth during their eruption processes, is a good model for revealing the inhibitory mechanism of bisphosphonate upon bone resorption. In the present study, RANKL and OPG expression were examined immunohistochemically in the mandible of rats with developing teeth after alendronate administration (2.5 mg/kg). The preeruptive mandibular first molars at postnatal days 3 to 10 showed the developing stages from bell to crown. No morphological changes in tooth formation were observed after alendronate administration. The number of osteoclasts in the alveolar bone around the developing teeth decreased markedly at postnatal days 3, 7 and 10 compared with the control group. RANKL induced strong positive immunohistochemical reactions in the dental follicles and stromal cells around the mandibular first molar. In particular, many osteoclasts with strongly positive reactions to RANKL appeared above the developing mandibular first molars at postnatal days 3 and 10. Immunohistochemical reactions with RANKL after alendronate administration were weaker than the control groups. However, the immunohistochemical reactivity to OPG was stronger after alendronate administration, at postnatal days 3 and 10. These results suggest that alendronate may decrease bone resorption by regulating the RANKL/OPG pathway in the process of osteoclast formation, resulting in a delay in tooth eruption.

Hereditary dentin defects consist of dentin dysplasia(DD) and dentinogenesis imperfecta(DI). The DI associated with osteogenesis imperfecta has been classified as DI type I, whereas isolated inherited defects have been categorized as DI types II and III. However, whether DI type III should be considered a distinct phenotype or a variation of DI type II is debatable. Recent genetic findings have focused attention on the role of the dentin sialophosphoprotein(DSPP) gene in the etiology of inherited defects of tooth dentin. We have identified a novel mutation(c.727G → A, p.D243N) at the 243th codon of exon 4 of the DSPP gene in a Korean patient with DI type III. The radiographic and histologic features of the patient revealed the classic phenotype of shell teeth. These findings suggest that DI type II and III are not separate diseases but rather the phenotypic variation of a single disease.

Hereditary dentin defects consists of dentin dysplasia(DD) and denti nogenesis imperfecta(Dr) ‘ The Dl associated with osteogenesis imperfecta has been classified as DI type 1. whereas isolated inherited defects have been categori zed as DI types II and III , However‘ whether DI type III should be considered a distinct phenotype 01' a variation of DI type 1I is debatable , Recent genetic findings have focused attention on the role of the dentin sialo phosphoprotein(DSPP) gene in the etiology of inherited defects of tooth dentin, We have identified novel mlltation( c,727G - > A, p,D243N) at the 243th codon of exon 4 of the DSPP gene in a Korean patient with DI type III The radiographic and histologic features of the patient revealed the classic phenotype of shell teeth These findings sllggest that DI type II and III are not separate diseases bllt rather the phenotypic variation 01' a s ingle disease

Abnormal number of deciduous teeth causes esthetic and dental problems on infants or children, which has effect on articulation disorder and emotional development as well as their physical growth. Therefore, it is important to detect dental problems early and to provide comparable indications. The purose of this study was to find out the prevalence and pattern in abnormal number of deciduous teeth. The clinical and radiographic examination was undertaken for 200 at age from 1 to 10 years and statistical analysis was done. The result were as follows. Among the examined patients, congenital missing teeth 8.6% and supernumerary teeth 36.4% were seen(p<0.05). And abnormal number of deciduous teeth was prevalent in male. Most supernumerary teeth located on middle area(88.6%) was seen(p<0.05). The most frequently missing teeth was the mandibular primary lateral incisor and the mandibular 2nd. premolar. And these teeth were mainly located in maxilla and right portion. It suggested that this study would play an important role for the basis of the demographic research of abnormal teeth in oral pathologic field

For the safety extirpation in case of acute pulpitis with painless procedure, lots of pulp devitalizers have been designed for a long time. Authors have manufactured experimental pulp devitalizer with adding some other constituents for main components of paraformaldehyde and local anesthetics. The purpose of this study was to observe the histopathologic tissue response in pulp tissues by applying newly developed safety pulp devitalizer to the human tooth. For this experiments 5 human teeth in 4 patients (ages of 26 to 49) were used. In case of acute pulpitis with pulp exposure, divided into two groups; One group, carious dentin removed, and then was applied newly developed devitalizer directly to exposed small pulp tissues. Other group, was exposed the pulp chamber, pulpotomized and then the devitalizer was applied to remaining pulp tissues. The teeth were extracted on 3rd and 7th day after operation respectively. For the control group, Depulpin? was used as pulp devitalizer. All the extracted teeth were fixed in 10% neutral formalin solution, decalcified in Plank-Richlo solution, embedded in paraffin, sectioned 6-8㎛ in thickness, stained with hematoxylin-eosin stain method, and examined under microscope. Attained results were as follows; 1. There were no difference in histopathologic aspects either exposed or not pulp chamber, the extent of necrosis of pulp tissue and destruction of odontoblast was similar to that on the 3rd day of control group and both the 3rd and 7th day of the experimental group. 2. For the necrosis of pulp tissue and destruction of odontoblast on the 3rd day of control group exposed pulp chamber, was similar to that on the 3rd day of experimental group exposed small pulp tissue. The experimental pulp devitalizer could reduce the side effects, which reduced the amount of paraformaldehyde components, adding other constituents, reduced the duration of pulp devitalization, and useful whether exposed or not the pulp chamber.

Normal development of human fetal teeth during prenatal period play an important role in analyzing abnormal teeth formation and examining pathologic approach to abnormal teeth formation. The purposes of this study were to describe the normal development of dental hard tissues in fetal teeth compared to abnormal teeth formation through review and literature. We will apply these study to examine the pathologic alterations of human teeth in the future.