Chang-Hyeon An

Proteomics Analysis of Human Dentin Reveals Distinct Protein Expression Profiles

The human tooth is the hardest organ of the body, and is composed of enamel, dentin, and dental pulp. Dentin provides the basis of the tooth shape by lining the inner parts of the root and crown. Odontoblasts deposit dentin, an organic matrix that contains collagen, noncollagenous proteins, phospholipids, and growth factors. In this study, we sought to reveal the proteins in human dentin by using liquid chromatography-tandem mass spectroscopy (LC-MS/MS) proteomic approaches. Human third molar dentins were cut, isolated, and demineralized, and the extracted proteins were separated on SDS-PAGE. In-gel digested peptides were analyzed using reverse-phase LC-MS/MS. We identified 233 total and 68 common proteins from 3 individuals with high confidence, including a variety of collagenous and noncollagenous proteins such as DSPP, biglycan, osteoglycin, osteopontin, and osteocalcin. In addition to known proteins, we also identified various matrix and serum proteins deposited in the dentin, including asporin, lumican, mimecan, and SOD3. This study provides the first list of proteomes that are detected in human dentin. This proteome list is useful in that it defines the organic matrix of dentin and helps to characterize odontoblasts.

Enhanced osteoconductivity of micro‐structured titanium implants (XiVE S CELLplus™) by addition of surface calcium chemistry: a histomorphometric study in the rabbit femur

OBJECTIVES This study evaluated the osseointegration in rabbit cancellous bone of titanium (Ti) implants with a micro-topographically complex surface structure produced by grit-blasting/acid-etching with or without the addition of surface calcium ion (Ca) chemistry. MATERIAL AND METHODS Micro-structured Ti implants (XiVE S CELLplus screw implant, Dentsply Friadent GmbH) were hydrothermally treated in an alkaline Ca-containing solution to produce a nano-structured Ca-incorporated oxide surface layer. The surface characteristics were evaluated by scanning electron microscopy and stylus profilometry before and after Ca surface treatment. Twenty implants (10 control and 10 experimental) were placed in the femoral condyles of 10 New Zealand White rabbits. Histomorphometric analysis was performed 6 weeks after implantation. RESULTS Ca-incorporated and untreated control implants showed similar surface morphologies and surface roughness values at the micron scale. Untreated micro-structured Ti implants achieved a high degree of bone-to-implant contact (BIC), and Ca incorporation further increased BIC% (P<0.05). Active new bone apposition was found on surfaces of Ca-incorporated implants in areas of loose trabeculae. CONCLUSION The nano-structured Ca-incorporated oxide surface significantly enhanced osteoconductivity of micro-structured Ti implants in rabbit cancellous bone. Results indicate that this surface produced by simple hydrothermal treatment may be effective in improving the osseointegration of implants with micro-topographically complex surface structures in areas of loose cancellous bone.

Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone

OBJECTIVE Recent studies have suggested that magnesium (Mg) ions exert a beneficial effect on implant osseointegration. This study assessed the osseointegration of nanoporous titanium (Ti) surface incorporating the Mg produced by hydrothermal treatment in rabbit cancellous bone to determine whether this surface would further enhance bone healing of moderately rough-surfaced implants in cancellous bone, and compared the result with commercially available micro-arc oxidized Mg-incorporated implants. MATERIAL AND METHODS The Mg-incorporated Ti surfaces (RBM/Mg) were obtained by hydrothermal treatment using an alkaline Mg-containing solution on grit-blasted moderately rough (RBM) implants. Untreated RBM and recently introduced Mg-incorporated microporous Ti implants produced by micro-arc oxidation (M) were used controls in this study. The surface characteristics were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and optical profilometry. Twenty-four threaded implants with a length of 10 mm (eight RBM implants, eight RBM/Mg implants and eight M implants) were placed in the femoral condyles of 12 New Zealand White rabbits. Histomorphometric analysis was performed 4 weeks after implantation. RESULTS Hydrothermally treated and untreated grit-blasted implants displayed almost identical surface morphologies and R(a) values at the micron-scale. The RBM/Mg implants exhibited morphological differences compared with the RBM implants at the nano-scale, which displayed nanoporous surface structures. The Mg-incorporated implants (RBM/Mg and M) exhibited more continuous bone apposition and a higher degree of bone-to-implant contact (BIC) than the untreated RBM implants in rabbit cancellous bone. The RBM/Mg implants displayed significantly greater BIC% than untreated RBM implants, both in terms of the all threads region and the total lateral length of implants (P<0.05), but no statistical differences were found between the RBM/Mg and M implants except BIC% values in total lateral length. CONCLUSION These results indicate that a nanoporous Mg-incorporated surface may be effective in enhancing the osseointegration of moderately rough grit-blasted implants by increasing the degree of bone-implant contact in areas of cancellous bone.

5‐HT1B receptors inhibit glutamate release from primary afferent terminals in rat medullary dorsal horn neurons

BACKGROUND AND PURPOSE Although 5‐HT1B receptors are expressed in trigeminal sensory neurons, it is still not known whether these receptors can modulate nociceptive transmission from primary afferents onto medullary dorsal horn neurons.

Odontoma: a retrospective study of 73 cases

Purpose The purpose of the present study was to retrospectively evaluate the clinical findings and treatment results for impacted permanent teeth associated with odontomas. Materials and Methods We retrospectively investigated 73 odontomas in 72 patients who visited Kyungpook National University Dental Hospital from April 2004 through November 2011. The study was performed using medical records, panoramic radiographs, and pathological reports. Data gathered included age, gender, location, chief complaints, effects on dentition, and treatment of odontoma and the impacted tooth associated with odontoma. Results Most compound odontomas (46.7%) were found in the second decade and complex odontomas were not related to age. Odontomas showed no gender predilection. Fifty-five cases (75.3%) of odontomas were detected on routine dental radiographs. Sixty percent of compound odontomas occurred in the canine area and 57.1% of complex odontomas in the molar areas. Impaction of permanent teeth (61.6%) was the most common complication on the adjacent teeth. Most odontomas (84.9%) were removed surgically and impacted permanent teeth were managed by surgical removal (53.2%), orthodontic treatment (25.5%), or surgical repositioning (6.4%). There was a statistically significant relation between age and preservation of the impacted permanent teeth associated with odontomas (p<0.01). Conclusion Early detection and treatment of odontomas increase the possibility of preservation of the impacted tooth. Therefore, it would be suggested that periodic panoramic examination during the first and second decade of life might be beneficial for the early detection and better prognosis of odontomas.

Contribution of Mesenchymal Proliferation in Tooth Root Morphogenesis

In mouse tooth development, the roots of the first lower molar develop after crown formation to form 2 cylindrical roots by post-natal day 5. This study compared the morphogenesis and cellular events of the mesial-root-forming (MRF) and bifurcation-forming (BF) regions, located in the mesial and center of the first lower molar, to better define the developmental mechanisms involved in multi-rooted tooth formation. We found that the mesenchyme in the MRF showed relatively higher proliferation than the bifurcation region. This suggested that spatially regulated mesenchymal proliferation is required for creating cylindrical root structure. The mechanism may involve the mesenchyme forming a physical barrier to epithelial invagination of Hertwig’s epithelial root sheath. To test these ideas, we cultured roots in the presence of pharmacological inhibitors of microtubule and actin polymerization, nocodazole and cytochalasin-D. Cytochalasin D also inhibits proliferation in epithelium and mesenchyme. Both drugs resulted in altered morphological changes in the tooth root structures. In particular, the nocodazole- and cytochalasin-D-treated specimens showed a loss of root diameter and formation of a single-root, respectively. Immunolocalization and three-dimensional reconstruction results confirmed these mesenchymal cellular events, with higher proliferation in MRF in multi-rooted tooth formation.

Texture analysis of mandibular cortical bone on digital dental panoramic radiographs for the diagnosis of osteoporosis in Korean women

OBJECTIVE To determine whether individual measurements or a combination of textural features and mandibular cortical width (MCW) derived from digital dental panoramic radiographs (DPRs) are more useful in assessment of osteoporosis. STUDY DESIGN Textural features were obtained by using fractal dimension (FD) and gray-level co-occurrence matrix (GLCM). Digital DPRs and bone mineral densities (BMDs) of the lumbar spine and the femoral neck were obtained from 141 female patients. A naïve Bayes classifier, a k-nearest neighbor (k-NN) algorithm, and a support vector machine were assessed for classifying osteoporosis. RESULTS The combinations of FD plus MCW (95.3%, 92.1%, 96.8%) and GLCM plus MCW (93.7%, 89.5%, 94.2%) for femoral neck BMD showed the highest diagnostic accuracy with the use of the naïve Bayes, k-NN, and support vector machine classifiers, respectively. CONCLUSIONS The combination of textural features and MCW contributed a better assessment of osteoporosis compared with the use of only individual measurements.

Rgs19 regulates mouse palatal fusion by modulating cell proliferation and apoptosis in the MEE.

Palatal development is one of the critical events in craniofacial morphogenesis. During fusion of the palatal shelves, removal of the midline epithelial seam (MES) is a fundamental process for achieving proper morphogenesis of the palate. The reported mechanisms for removing the MES are the processes of apoptosis, migration or general epithelial-to-mesenchymal transition (EMT) through modulations of various signaling molecules including Wnt signaling. RGS19, a regulator of the G protein signaling (RGS) family, interacts selectively with the specific α subunits of the G proteins (Gαi, Gαq) and enhances their GTPase activity. Rgs19 was reported to be a modulator of the Wnt signaling pathway. In mouse palatogenesis, the restricted epithelial expression pattern of Rgs19 was examined in the palatal shelves, where expression of Wnt11 was observed. Based on these specific expression patterns of Rgs19 in the palatal shelves, the present study examined the detailed developmental function of Rgs19 using AS-ODN treatments during in vitro palate organ cultivations as a loss-of-function study. After the knockdown of Rgs19, the morphological changes in the palatal shelves was examined carefully using a computer-aided three dimensional reconstruction method and the altered expression patterns of related signaling molecules were evaluated using genome wide screening methods. RT-qPCR and in situ hybridization methods were also used to confirm these array results. These morphological and molecular examinations suggested that Rgs19 plays important roles in palatal fusion through the degradation of MES via activation of the palatal fusion related and apoptotic related genes. Overall, inhibition of the proliferation related and Wnt responsive genes by Rgs19 are required for proper palatal fusion.

Hard and soft tissue changes of osteomyelitis of the jaws on CT images

OBJECTIVES This study aimed to assess the hard and soft tissue changes in osteomyelitis (OM) of the jaws using CT images. STUDY DESIGN The CT images of 153 patients (59 males and 94 females) with OM of the jaws were retrospectively reviewed. The relationships between each space involvement, between space and muscle involvements, between cortical bone defect and space involvement, and between cortical bone defect and muscle involvement were evaluated. RESULTS The cortical bone defect was more common on the buccal side in the maxilla and on the lingual side in the mandible. The most commonly involved muscle was the buccinator muscle in the maxilla and the masseter muscle in the mandible and the most frequently involved space was the buccal space followed by the masticator space. CONCLUSIONS CT is a useful tool in evaluating both hard and soft tissue changes of OM of the jaws.

Developmental regulations of Perp in mice molar morphogenesis

Teraspanin transmembrane protein, Perp (P53 apoptosis effector related to PMP22), which is found in the plasma membrane as a component of the desmosome, is reported to be involved in the morphogenesis of the epithelium and the enamel formation of the incisor. However, its expression pattern and signaling regulation during molar development have not been elucidated in detail. We have examined the precise expression patterns of Perp in developing lower molars and employed the knock-down of Perp by antisense oligodeoxynucleotide treatment during in vitro organ cultivation at embryonic day 13 to define the precise developmental function of Perp. Perp was expressed mainly in the dental lamina and stellate reticulum regions at the bud and cap stages. After Perp knock-down, the tooth germ showed disruption of the dental lamina and stellate reticulum with altered apoptosis and proliferation. The changed expression levels of related signaling molecules from the enamel knot and desmosome were evaluated by real-time quantitative polymerase chain reaction. A renal capsule transplantation method was employed to examine the effects of Perp knock-down on molar crown development. Ultrastructural observations revealed that enamel was deposited more densely in an irregular pattern in the cusp region, and that dentin was hypo-mineralized after Perp knock-down at the cap stage. Thus, Perp might play important roles in the formation and integration of stellate reticulum, dental lamina structure and enamel formation through signaling interactions with the enamel knot and desmosome-related signaling molecules at the cap stage of lower molar development.