Development of an error-detection examination for conservative dentistry education.

OBJECTIVE: For dental students, textbooks and lectures provide basic knowledge, and simulated and actual clinical training provide learning in technical and communication skills. At our college, conservative dentistry is taught in the third and fourth years of a 6-year undergraduate degree. Clinical training is undertaken subsequently in the fifth year and includes cavity preparation and composite resin filling tasks. However, despite the clinical importance of a full understanding surrounding these procedures, sixth-year students occasionally provide incorrect answers regarding these procedures in assessments. Although they demonstrated a basic understanding of the procedures, they may have forgotten the acquired knowledge during their clinical training. Therefore, we developed an error-detection examination to evaluate and improve fifth-year students' knowledge. METHODS: Written detailed treatment procedures for standardized, typical, cases were presented to students. Some critical steps were intentionally written incorrectly, and students had to identify and correct these. After correcting the steps, students gave a presentation to their peers on their corrections. This was followed by a summary of the correct answers and a short lecture by the teacher. Students then completed a questionnaire investigating their experience of the examination. RESULTS: Students misunderstood some key treatment steps, such as pretreatment of composite resin filling, amalgam removal, and ceramic inlay fitting. The questionnaire revealed that this method of testing applied knowledge was new to students and helped them to identify knowledge gaps. The test also increased their motivation to study conservative dentistry. Students were open to taking similar tests in different areas. CONCLUSION: Although conservative dentistry is a basic field of dental treatment, mistakes in treatment can lead to early treatment failure or reduce the lifetime of a restored tooth. Therefore, students need to have a deep understanding of procedures. Error-detection examinations may help students identify knowledge gaps and provide useful feedback to teachers to identify areas that they should stress in earlier years.

Induction of bone repair in rat calvarial defects using a combination of hydroxyapatite with phosphatidylserine liposomes.

Phosphatidylserine (PS)-normally present on the inner leaflet of the plasma membrane-translocates to the outer leaflet at an early stage of apoptosis. PS-containing liposomes (PSLs) can mimic the effect of apoptotic cells in inducing the secretion of prostaglandin E2 from phagocytes and inhibiting the maturation of dendritic cells and osteoclast precursors. The present study attempted to evaluate the effect of calcium phosphate (in the form of hydroxyapatite [HAP]) in the presence or absence of PSLs for repair of rat calvarial bone defects. The defects, each 5 mm in diameter, were created in the calvaria parietal bone of 8-week-old Wistar rats and subjected to one of the following treatments: no augmentation (Sham), HAP alone, or a mixture of HAP and PSL (HAP+PSL). Micro-computed tomography data showed that the HAP+PSL complexes promoted greater bone regeneration in comparison with either the Sham procedure or HAP alone at 4 and 8 weeks after implantation. The regeneration of calvarial bone defects induced by PSLs was mediated partly through upregulation of the osteogenic marker Alkaline Phosphatase, Type I collagen, osteocalcin, Runx2, and Osterix mRNAs. These data are the first to show that PSLs can influence bone regeneration by regulating osteoblast differentiation.

Impact of psoas muscle index on short-term outcome after living donor liver transplantation.

BACKGROUND/AIMS: Living donor liver transplantation is an operation with high morbidity and mortality rates. The purpose of this study was to examine factors affecting the short-term outcome after living donor liver transplantation. MATERIALS AND METHODS: Forty-seven adult patients who underwent living donor liver transplantation from September 2001 to December 2014 were included. Short-term post-transplant outcomes were evaluated in terms of the onset of postoperative complications of grade 3a and above (Clavien-Dindo classification) and postoperative 120-day mortality. Univariate and multivariate analyses were used to determine possible predictive factors among perioperative variables such as preoperative psoas muscle index (PMI), blood laboratory test results, perioperative nutritional therapy, and operative factors. RESULTS: Lower PMI (lower than the first quartile of PMI of donors), higher blood urea nitrogen level (≥14 mg/dL), and blood type incompatibility were independent risk factors for the development of postoperative complications. The 120-day survival rates were significantly lower for the lower PMI group (n=30, 66.7%) than for the higher PMI group (n=17, 94.1%, p=0.034). CONCLUSION: A significant correlation was observed between preoperative PMI and short-term postoperative outcomes. Sarcopenia estimated by PMI may serve as a measure of patient frailty and a target for risk stratification.

Histologic evaluation of the effects of Emdogain gel on injured root apex in rats.

INTRODUCTION: This study investigated the effects of Emdogain gel (EMD) on the injured open apex within periapical lesions. METHODS: Periapical lesions were induced in rats by opening the pulp chambers of the mandibular first molars and filing the apical foramen through the distal root canal with #25 K-files to make an open apex. The teeth were exposed to the oral environment for 7 days. Then we irrigated the distal root canals and divided them into EMD-treated and propylene glycol alginate-treated groups. The rats were killed 7, 14, and 28 days after treatment and examined histochemically. RESULTS: In the EMD-treated rats, more cells expressed transforming growth factor-ß1 or bone morphogenetic protein-2 at 7 days after treatment, and the regeneration of cementum and bone was observed around the root apex at 14 days after treatment. Conversely, in the propylene glycol alginate-treated group, few cells expressed transforming growth factor-ß1 or bone morphogenetic protein-2, and apical periodontal tissue recovery was rarely seen within the periapical lesions throughout the experiment. CONCLUSIONS: These results suggest that EMD does not irritate injured periapical tissue and may create a favorable environment that promotes the healing of destroyed periapical tissues.

Pro-inflammatory cytokines induce suppressor of cytokine signaling-3 in human periodontal ligament cells.

INTRODUCTION: Periapical inflammation is initiated by insult to the dental pulp and mediated by inflammatory cytokines in the periodontal tissue. On the other hand, the destruction of tissue can be prevented by the suppression of pro-inflammatory cytokine activity. The balance between these cytokines and their counterregulatory molecules has been suggested to regulate tissue destruction. Suppressors of cytokine signaling (SOCS) proteins are known to suppress inflammatory cytokine signaling via the classic negative feedback loop. However, the mechanism by which they are induced by inflammatory cytokines and regulated during the development of periodontal disease remains to be clarified. We investigated the effects of inflammatory cytokines on SOCS protein expression and their signaling pathways in human periodontal ligament (PDL) cells. METHODS: We examined the effect of inflammatory cytokines on SOCSs expression and its signaling pathway in human PDL cells using reverse transcription- and real-time polymerase chain reaction, Western blot methods. Furthermore, we also examined whether these cytokines-induced SOCS-3 suppress chemokines secretion using ELISA methods. RESULTS: We found that inflammatory cytokines interleukin (IL)-1beta and IL-6 induced expression of SOCS-3 but not that of SOCS-2 in human PDL cells. IL-1beta and IL-6 simultaneously induced IL-8 and monocyte chemoattractant protein-1 secretion in PDL cells, whereas SOCS-3 overexpression suppressed secretion of these chemokines through inhibition of phosphorylation in downstream signaling. CONCLUSION: The results suggest that pro-inflammatory cytokines induced SOCS-3 expression. The SOCS-3 induction suggests playing an important role in negative feedback, suppressing serious destruction of periodontal tissue in apical periodontitis through a chemokine-dependent mechanism.

Immunohistochemical localization of metallothionein in dental pulp after cavity preparation of rat molars.

OBJECTIVE: Metallothionein (MT) is an intracellular cysteine-rich protein associated with cell proliferation and differentiation. Our objective was to examine immunohistochemically the localization of MT in the rat dental pulp after cavity preparation. STUDY DESIGN: Cavities were prepared on the upper first molars of 9 rats. Specimens were collected at 1, 3, and 5 days after cavity preparation, and paraffin sections were made. For double-immunohistochemical staining, anti-MT monoclonal antibody (E9) and anti-proliferating cell nuclear antigen (PCNA) monoclonal antibody (PC10) were applied. RESULTS: At 3 days after cavity preparation, some odontoblasts corresponding to the cavity, many pulp cells, and some endothelial cells in the pulp under the cavity showed both MT- and PCNA-positive immunostainings. CONCLUSION: Metallothionein was detected in the dental pulp after pulp injury, and it is likely that MT is closely related to the proliferation of newly differentiating odontoblasts and angiogenesis during the healing process.

Short-term histomorphological effects of Er:YAG laser irradiation to rat coronal dentin-pulp complex.

OBJECTIVE: The objective of the study was to examine the morphological changes of neural elements in dentin-pulp complex ultrastructurally after Er:YAG laser irradiation and elucidate the mechanism of pain reduction in cavity ablation. STUDY DESIGN: The Er:YAG laser was applied at occlusal surfaces of upper and lower first molar cusps of 6 rats, and shallow cavities were ablated. The dentin and pulps were examined with light and electron microscopes at 6 hours after the irradiation. Teeth, without laser irradiation, from three rats were used as controls. RESULTS: Disruption of nerve terminals in the dentinal tubules, degeneration of nerve terminals between odontoblasts, and disruption of the myelin sheath in the pulp core were demonstrated with electron microscope. CONCLUSION: Some Er:YAG laser beams could penetrate to deeper areas than ablated area, and damage of nerve fibers and terminals might be a mechanism of pain reduction in cavity ablation with Er:YAG laser.

Age-related changes in the immunoreactivity of the monocyte/macrophage system in rat molar pulp after cavity preparation.

OBJECTIVE: Our objective was to compare the response of the monocyte/macrophage system of dental pulp to cavity preparation in aged rats (12 and 18 months old) with that seen in young adult rats (3 and 6 months old). STUDY DESIGN: Cavities were prepared on the upper first molars, and the lower first molars served as intact controls. Specimens were collected at 1 day after cavity preparation, and cryostat sections were made. RESULTS: Accumulation of OX6+ antigen-presenting cells along the pulp-dentin border and a marked increase in cell size ED2+ resident macrophages were noted in both young adult and aged rats after cavity preparation. In both cases, the number of ED1+ cells increased significantly after cavity preparation because of infiltrating monocytes. CONCLUSION: These findings suggest that the pulpal defense reaction of the monocyte/macrophage system to cavity preparation in aged rats does not differ markedly from that in young adult rats.