Purpose: The purpose of this study was to assess the adhesiveness and cytotoxicity of 3, 4-dihydroxyphenylalanine (DOPA), and to evaluate the role of collagen membrane with DOPA in the guided bone regeneration. Materials and Methods: Peel resistance and cell cytotoxicity test were performed. Four defect types in nine rabbit calvaria were randomly allocated: i) control, ii) membrane, iii) deproteinized porcine bone mineral (DPBM) covered by membrane with DOPA, and iv) DPBM covered by membrane with cyanoacrylate. Animals were sacrificed at 2 (n=4) and 8 weeks (n=5) for microcomputed tomography and histomorphometric analysis. DOPA showed low peel resistance but high cell viability. Result: Cyanoacrylate and DOPA groups showed significantly higher mineralized tissue volume (MTV) compared to control and membrane groups at 2 weeks (P<0.05). At 8 weeks, DOPA group showed the highest MTV. Significantly higher new bone area was found in DOPA group at 8 weeks (P<0.05). Bone formation increased from 2 to 8 weeks in DOPA group (P<0.05). Conclusion: DOPA showed high cell viability and in vivo study revealed predictable performance in bone regeneration.

Purpose: Polydeoxyribonucleotide (PDRN), consisting of a mixture of deoxyribonucleotide polymers, has been suggested to have anti-inflammatory effects and enhance angiogenesis as an adenosine $A_{2A}$ receptor agonist. The aim of this study was to report the effectiveness of PDRN as an adjuvant therapy after surgical debridement in MRONJ (medication-related osteonecrosis of the jaw) patients. Materials and Methods: Five patients (1 male, 4 females, age 65~79 years) who were diagnosed with MRONJ stage 2 or 3 underwent surgical debridement and PDRN mucosal injection. After surgical debridement, patients were subject to daily injection with 1 ml of PDRN around the surgical wound for 14 days. Result: The patients' symptoms gradually disappeared. The surgical wound uneventfully healed, and no recurrence was observed during the follow-up period. Conclusion: Although further studies are required, the present study first describes the possibility of PDRN as a useful option for MRONJ treatment.

Purpose: Bone marrow has long been a source of primary cells. This study was performed to evaluate the effects of age and sex on the cellular viability and expression of stem cell markers of mRNA and on the protein expression of bone marrow stem cells (BMSCs) derived from healthy donors. Materials and Methods: Stem cells were isolated from human bone marrow and plated in culture plates. The shape of the BMSCs was observed under inverted microscope. Quantitative cellular viability was evaluated using a Cell-Counting Kit-8 assay. The expression of stem cell surface markers was tested and a series of quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot was performed to evaluate the expression in each group. Result: The shapes of the cells at 20s, 30s, and 50s were similar to each other. No significant changes in cellular viability were noted among different age groups or sex groups. The BMSCs expressed CD44, CD73, and CD90 surface markers but did not express CD14 and CD34. There were no noticeable differences in CD surface markers among the different age groups. The expressions of CD surface markers were similar between men and women. No significant differences in the secretion of vascular endothelial growth factors (VEGFs) were noted at Day 3 between different age groups. qRT-PCR regarding the expression showed differences between the age groups. However, Western blot analysis showed a decrease in expression but did not reach statistical significance (P>0.05). Conclusion: This study clearly showed no significant differences in shape, cell viability, expression of stem cell surface markers, or secretion of human VEGF among different age groups. However, western blot analysis showed a tendency of age-related decrease which did not reach statistical significance. Collectively, autologous or allogeneic BMSCs should be meticulously applied to obtain optimal results regarding age and sex.

Purpose: The purpose of this study was to investigate the corrosion behaviors of dental implant alloy after microsized surface modification in electrolytes containing Mn ion. Materials and Methods: $Mn-TiO_2$ coatings were prepared on the Ti-6Al-4V alloy for dental implants using a plasma electrolytic oxidation (PEO) method carried out in electrolytes containing different concentrations of Mn, namely, 0%, 5%, and 20%. Potentiodynamic method was employed to examine the corrosion behaviors, and the alternatingcurrent (AC) impedance behaviors were examined in 0.9% NaCl solution at $36.5^{\circ}C{\pm}1.0^{\circ}C$ using a potentiostat and an electrochemical impedance spectroscope. The potentiodynamic test was performed with a scanning rate of $1.667mV\;s^{-1}$ from -1,500 to 2,000 mV. A frequency range of $10^{-1}$ to $10^5Hz$ was used for the electrochemical impedance spectroscopy (EIS) measurements. The amplitude of the AC signal was 10 mV, and 5 points per decade were used. The morphology and structure of the samples were examined using field-emission scanning electron microscopy and thin-film X-ray diffraction. The elemental analysis was performed using energy-dispersive X-ray spectroscopy. Result: The PEO-treated surface exhibited an irregular pore shape, and the pore size and number of the pores increased with an increase in the Mn concentration. For the PEO-treated surface, a higher corrosion current density ($I_{corr}$) and a lower corrosion potential ($E_{corr}$) was obtained as compared to that of the bulk surface. However, the current density in the passive regions ($I_{pass}$) was found to be more stable for the PEO-treated surface than that of the bulk surface. As the Mn concentration increased, the capacitance values of the outer porous layer and the barrier layer decreased, and the polarization resistance of the barrier layers increased. In the case of the Mn/Ca-P coatings, the corroded surface was found to be covered with corrosion products. Conclusion: It is confirmed that corrosion resistance and polarization resistance of PEO-treated alloy increased as Mn content increased, and PEO-treated surface showed lower current density in the passive region.

Leukemia is a hematological malignant disease with various clinical symptoms. Due to the fatal nature of the disease, early detection is important. Oral manifestations include ulcers and gingival enlargement with bleeding. Moreover, myeloid sarcoma or opportunistic infections may also occur. This report introduces a 31-year-old male presenting with generalized gingival enlargement with bleeding and another 81-year-old female with neoplasm on the left retromolar area. Both were diagnosed as acute monocytic leukemia. These cases implicate that gingival enlargement or mucosal lesion in the oral cavity may represent underlying systemic diseases. Related to this, it has to be reminded that making timely diagnosis and referral according to the clinical findings is crucial.

Ameloblastomaa are odontogenic benign tumors with epithelial origin, which are characterized by slow, aggressive, and invasive growth. Most ameloblastomas occur in the mandible, and their prevalence in the maxilla is low. A 27-year-old male visited our clinic with a chief complaint of the left side nasal airway obstruction. Three-dimensional computed tomography showed left maxillary sinus filled with a mass. Except for the perforated maxillary left edentulous area, no invaded or destructed bone was noted. The tumor was excised via Le Fort I osteotomy. The main mass was then sent for biopsy and it revealed acanthomatous ameloblastoma. The lesion in the left maxillary sinus reached the ethmoidal sinus through the nasal cavity but did not invade the orbit and skull base. The tumor was accessed through a Le Fort I downfracture in consideration of the growth pattern and range of invasion. The operation site healed without aesthetic appearances and functional impairments. However, further long-term clinical observation is necessary in the future for the recurrence of ameloblastoma. Conservative surgical treatment could be the first choice considering fast recovery after surgery and the patient's life quality.