Wonse Park

Mesiobuccal root canal anatomy of Korean maxillary first and second molars by cone-beam computed tomography

OBJECTIVE The aim of this study was to investigate the types of canal configurations and the incidence of a second mesiobuccal (MB2) canal in Korean maxillary molar mesiobuccal (MB) roots by analyzing cone-beam computed tomographic (CBCT) images. STUDY DESIGN Three-dimensional CBCT images of 458 maxillary first molars and 467 second molars from 276 Korean patients were analyzed to determine the incidence of an MB2 canal, the types of canal configurations, and the correlations between the incidence of an MB2 canal and age, gender, and tooth position. RESULTS The incidence of 2-canaled MB roots was 71.8% in first molars and 42.2% in second molars, with the most common configurations being Weine types III and II. The frequency of an MB2 canal decreased with age in both molars (P < .05). CONCLUSIONS Types III and II canal configurations were the most prevalent in the 2-canaled MB roots of Korean maxillary molars.

Effect of EDTA on Attachment and Differentiation of Dental Pulp Stem Cells

INTRODUCTION In regenerative endodontics, it is believed that EDTA induces odontoblast differentiation by releasing growth factors from the dentin matrix. The aim of this study was to evaluate the effect of EDTA on the attachment and differentiation of dental pulp stem cells (DPSCs). We also investigated whether the behavioral changes of DPSCs could be caused by biochemical components released from EDTA-treated dentin. METHODS Cells were obtained from human third molars, and the stem-like nature of the cells was investigated by flow cytometric analysis. DPSCs were seeded on EDTA-treated and untreated dentin slices. After 3 days of culture, cell attachment was evaluated by cell density, fibronectin 1 gene expression level using quantitative real-time polymerase chain reaction, and scanning electron microscopy. After 21 days of culture, the expression of differentiation genes was investigated by quantitative real-time polymerase chain reaction, and calcification was observed using alizarin red S staining. To investigate the EDTA-induced growth factor release, DPSCs were cultured with or without direct contact with the EDTA-treated dentin surface. RESULTS After 3 days of culture, both the cell density and fibronectin expression level were significantly higher in the EDTA-treated dentin group. After 3 weeks, the DPSCs on the EDTA-treated dentin surfaces showed higher expression levels of dentin sialophosphoprotein and dentin matrix protein 1, whereas the DPSCs cultured without direct contact with the EDTA-treated dentin surfaces did not exhibit these findings. CONCLUSIONS Our results showed that EDTA induced cell attachment and odontoblastic/osteoblastic differentiation, which was observed only in the group in which the DPSCs were placed in direct contact with the EDTA-treated dentin surfaces. These findings suggest that EDTA is beneficial for achieving successful outcomes in regenerative endodontics.

Integration accuracy of digital dental models and 3-dimensional computerized tomography images by sequential point- and surface-based markerless registration

OBJECTIVE The goal of this study was to evaluate the accuracy of the integration of computerized tomography (CT)-based bone models and laser-scanned dental models by sequential point- and surface-based markerless registration to create a digital maxillofacial-dental model. STUDY DESIGN The integration accuracy was evaluated in normal skulls (group I) and subjects with maxillofacial deformities (group II) by measuring the distance between the integrated models (for group I and II) and between the final integrated model and the laser-scanned original skull model (for group I). RESULTS The average error ranged between 0 and 0.2 mm without statistically significant difference in the region of maxilla or mandible and in tooth location. CONCLUSIONS We could confirm that the integration can be made with good accuracy without the aid of fiducial markers for the maxillofacial-dental composite model from the different resolution of CT and dental models.

Diplopia after inferior alveolar nerve block anesthesia: Report of 2 cases and literature review

Inferior alveolar nerve block (IANB) anesthesia is one of the most common procedures in the dental clinic. Although this procedure is well known for its safety, complications can still occur. An ocular complication such as diplopia, loss of vision, or ophthalmoplegia is very rare, but once it happens, both the dentist and patient can be perplexed by the unexpected circumstance, and the doctor-patient trust may be harmed. We experienced 2 cases of diplopia after IANB anesthesia. This report describes the cause and diagnosis of the associated symptoms and includes a review of the literature.

Clinical experiences of digital model surgery and the rapid-prototyped wafer for maxillary orthognathic surgery

OBJECTIVE The aim of this study was to present our clinical experience regarding the production and accuracy of digitally printed wafers for maxillary movement during the bimaxillary orthognathic surgery. STUDY DESIGN Fifty-five consecutive patients requiring maxillary orthognathic surgery were included in this study. The plan for digital model surgery (DMS) was dictated by the surgical plans for each clinical case. We carried out digital model mounting, DMS, wafer printing, and confirmation of the accuracy of the procedure. RESULTS Moving the reference points to the target position in DMS involved a mean error of 0.00-0.09 mm. The mean errors confirmed by the model remounting procedure with the printed wafer by DMS were 0.18-0.40 mm (for successful cases; n = 42) and 0.03-1.04 mm (for poor cases; n = 3). CONCLUSION The accuracies of the wafers by DMS were similar to those for wafers produced by manual model surgery, although they were less accurate than those produced by DMS alone. The rapid-prototyped interocclusal wafer produced with the aid of DMS can be an alternative procedure for maxillary orthognathic surgery.

Induction of IL-8 in periodontal ligament cells by H(2)O (2).

Periodontitis is an inflammatory disease caused by bacteria. In periodontitis, reactive oxygen species (ROS) are released from inflammatory cells in response to bacteria. Interleukin (IL)-8 is one of pro-inflammatory cytokines. To investigate the role of ROS in pathogenesis of periodontitis, we estimated the effect of H2O2, one of ROS, on the expression of IL-8 in human periodontal ligament (PDL) cells. PDL cells were treated with H2O2. IL-8 expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38) and c-jun NH2-terminal kinase (JNK) was estimated by Western blotting. Treatment with H2O2 at concentration of up to 250 μM increased IL-8 mRNA expression and production in a concentration-dependent manner. However, treatment with 500 μM H2O2 did not increase IL-8 production. Catalase, an inhibitor of H2O2, down-regulated the production of IL-8 induced by H2O2. H2O2 increased the phosphorylation of ERK, p38, and JNK. Pretreatment with PD98059 (ERK inhibitor), SB203580 (p38 inhibitor), or SP600125 (JNK inhibitor) decreased the IL-8 production induced by H2O2. These results indicate that H2O2 acts as an inducer of IL-8 secretion via activation of ERK, p38, and JNK in PDL cells. H2O2 deposited in periodontal tissue during inflammation against bacteria may accelerate tissue destruction via induction of IL-8 in PDL cells.

Comparative gene expression analysis of the human periodontal ligament in deciduous and permanent teeth.

There are histological and functional differences between human deciduous and permanent periodontal ligament (PDL) tissues. The aim of this study was to determine the differences between these two types of tissue at the molecular level by comparing their gene expression patterns. PDL samples were obtained from permanent premolars (n = 38) and anterior deciduous teeth (n = 31) extracted from 40 healthy persons. Comparative cDNA microarray analysis revealed several differences in gene expression between the deciduous and permanent PDL tissues. These findings were verified by qRT-PCR (quantitative reverse-transcription–polymerase chain reaction) analysis, and the areas where genes are expressed were revealed by immunohistochemical staining. The expressions of 21 genes were up-regulated in deciduous relative to PDL tissues, and those of 30 genes were up-regulated in permanent relative to deciduous PDL tissues. The genes that were up-regulated in deciduous PDL tissues were those involved in the formation of the extracellular matrix (LAMC2, LAMB3, and COMP), tissue development (IGF2BP, MAB21L2, and PAX3), and inflammatory or immune reactions leading to tissue degradation (IL1A, CCL21, and CCL18). The up-regulated genes in permanent PDL tissues were related to tissue degradation (IL6 and ADAMTS18), myocontraction (PDE3B, CASQ2, and MYH10), and neurological responses (FOS, NCAM2, SYT1, SLC22A3, DOCK3, LRRTM1, LRRTM3, PRSS12, and ARPP21). The analysis of differential gene expressions between deciduous and permanent PDL tissues aids our understanding of histological and functional differences between them at the molecular level.

Architectural characteristics of the normal and deformity mandible revealed by three-dimensional functional unit analysis.

The 3D architecture of the mandible contributes to the functional and morphological characteristics of the lower one third of craniofacial region. The mandible has six distinct functional units, and its architecture is the sum of balanced growth of each functional unit and surrounding matrix. A dentofacial deformity (DFD) with malocclusion can be interpreted as their unbalanced growth. In order to characterize the mandibular 3D architecture, we analyzed the 3D reconstructed computed tomography (CT) images in terms of functional units. We evaluated both sides of 30 datasets of 3D CT scans of normal controls (N = 6) and patients with prognathic (N = 17) or retrognathic (N = 7) mandibles. We first identified and evaluated reference points to define mandibular functional units and compared their linear and angular measurements of DFD with normal group. The condylar and body length, the ratio of condyle/coronoid length, and the condylar head axis angle showed the statistically significant differences between groups. From these results, we could define the 3D reference points for functional units and identify the 3D architectural characteristics of DFD mandibles. These models may help us improve diagnosis and treatment planning to let them return to the normal and balanced architecture for DFD.

Denosumab-related osteonecrosis of the jaw: a case report and management based on pharmacokinetics

Denosumab, a monoclonal antibody against the receptor activator for nuclear factor-kappa B ligand (RANKL), is a recently approved antiresorptive drug that suppresses osteoclast formation by targeting preosteclasts, in contrast to the traditional antiresorptive bisphosphonates that target mature osteoclasts. Osteonecrosis of the jaw (ONJ) is a well-known, if rare, side effect of bisphosphonate therapy; however, cases of ONJ have also been reported since 2010 in patients taking denosumab. We describe here a patient who developed ONJ while receiving denosumab; the pharmacokinetics of denosumab and bisphosphonates are discussed in the context of ONJ management.

Accurate computerised mandibular simulation in orthognathic surgery: a new method for integrating the planned postoperative occlusion model.

Department of Oral and Maxillofacial Surgery, National Health Insurance Corporation Ilsan Hospital, 1232, Baekseok-dong, Ilsan-donggu, Goyang-si, yeonggi-do, 410-719, Republic of Korea Department of General Dentistry, Dental Hospital, Yonsei University, 134 Shinchon-dong, Seodaemun-Ku, Seoul, 120-752, Republic of Korea Department of Oral & Maxillofacial Surgery, College of Dentistry, Yonsei University, 134 Shinchon-dong, Seodaemun-Ku, Seoul, 120-752, epublic of Korea