Myung Rae Kim

Which risk factors are associated with neurosensory deficits of inferior alveolar nerve after mandibular third molar extraction

PURPOSE Mandibular third molar extraction is a commonly performed procedure and is recognized as a relatively frequent cause of inferior alveolar nerve (IAN) injury. The aim of the present study was to investigate the specific risk factors for neurosensory deficits, including age, gender, impaction depth, angulation of the third molar, and various radiographic superimposition signs. MATERIALS AND METHODS In a case-control study of patients who had undergone mandibular third molar extraction, a case group was developed of patients showing neurosensory deficits of the IAN, and a control group was formed of randomly selected patients without any neurosensory symptoms. Bivariate analyses were performed to assess the relationship between each variable and IAN injury. A multivariate logistic regression model was used to compute the odds ratios, P values, and predictive values of the radiographic superimposition signs. RESULTS Of 12,842 total patients, the study group included 104 cases and 135 controls. The results indicated that older age and deeper impaction status were significant risk factors (P < .05). Darkening of the roots, deflection of the roots, narrowing of the roots, dark and bifid apexes of the roots, and narrowing of the canal were also significant risk factors. The positive predictive values ranged from 0.7% to 6.9% and the negative predictive values from 99% to 100%, with adjustment for the definitive prevalence of IAN injury (0.81%, 104/12,842 patients). However, the relatively low positive predictive value renders questionable the predictability of superimposition signs on orthopantomography. In the absence of specific radiographic signs, the risk of neurosensory deficit of the IAN could be negligible. The sensory symptoms disappeared after 6 months in 92.3% of the patients and 98.1% showed recovery after 1 year. CONCLUSIONS The results of the present study have demonstrated a significant association between several risk factors and neurosensory deficits of the IAN after third molar extraction. With a case group of 104 patients, the number of subjects was significantly greater than that in previous studies, increasing the reliability of these results.

Prospective biomarker evaluation in patients with osteonecrosis of the jaw who received bisphosphonates

Bone biomarkers have been suggested for the risk assessment for osteonecrosis of the jaw, a serious complication associated with bisphosphonate (BP) use; however, no consensus has been reached. This study investigated the possible associations between bone biomarkers and the development of bisphosphonates-related osteonecrosis of the jaw (BRONJ). This is a case-control study of 37 patients with BRONJ (age, 73.6±11.2years) who had at least 1 sample available at diagnosis, out of which, 35 were taking BPs for osteoporosis and 2 patients for bone metastasis. Age- and gender-matched 37 patients who had been exposed to BPs for >24months and had no evidence of BRONJ after dentoalveolar surgery served as control group. The association between biomarkers (osteocalcin [OC], deoxypyridinoline [DPD], C-terminal telopeptide of collagen I [CTX], N-terminal telopeptides [NTX], bone-specific alkaline phosphatase [BAP], and parathyroid hormone [PTH]) and BRONJ development, the effects of BP discontinuation on biomarkers, and the performance of biomarkers for risk assessment were investigated. In our study, the PTH levels were found to be significantly higher in BRONJ patients compared to controls (P<0.05). But the OC, DPD, CTX, NTX, and BAP levels were not significantly different between the 2 groups (P>0.05). The CTX level in reference to a 150pg/mL cutoff was also not significant for BRONJ development (P>0.05). Among BRONJ patients who discontinued BP, in a linear mixed model, only CTX showed a significant increase over time (β=0.002, P=0.007). The cutoff PTH level was >41.52pg/mL (AUC=0.719, P=0.009), and that of CTX was ≤0.094ng/mL (AUC=0.619, P=0.069). In conclusion, there is insufficient evidence for the risk prediction for BRONJ of current bone biomarkers; additional research is necessary.

Effects of polycaprolactone-tricalcium phosphate, recombinant human bone morphogenetic protein-2 and dog mesenchymal stem cells on bone formation: pilot study in dogs.

Purpose The aim of this study was to evaluate the survival, proliferation, and bone formation of dog mesenchymal stem cells (dMSCs) in the graft material by using Polycaprolactone-tricalcium phosphate (PCL-TCP), auto-fibrin glue (AFG), recombinant human bone morphogenetic protein-2 (rhBMP-2), and dMSCs after a transplantation to the scapula of adult beagle dogs. Materials and Methods The subjects were two beagle dogs. Total dose of rhBMP-2 on each block was 10 µg with 50 µg/mg concentration. The cortical bone of the scapula of the dog was removed which was the same size of PCL-TCP block (Osteopore International Pte, Singapore; 5.0×5.0×8.0 mm in size), and the following graft material then was fixed with orthodontic mini-implant, Dual-top® (Titanium alloy, Jeil Co. Seoul, Korea). Four experimental groups were prepared for this study, Group 1: PCL-TCP + aFG; Group 2: PCL-TCP + aFG + dMSCs; Group 3: PCL-TCP + aFG + dMSCs + rhBMP-2; Group 4: PCL-TCP + aFG + dMSCs + rhBMP-2 + PCL membrane. The survival or proliferation of dMSCs cells was identified with an extracted tissue through a fluorescence microscope, H-E staining and Von-Kossa staining in two weeks and four weeks after the transplantation. Results The survival and proliferation of dMSCs were identified through a fluorescence microscope from both Group 1 and Group 2 in two weeks and four weeks after the transplantation. Histological observation also found that the injected cells were proliferating well in the G2, G3, and G4 scaffolds. Conclusion This study concluded that bone ingrowth occurred in PCL-TCP scaffold which was transplanted with rhBMP-2, and MSCs did not affect bone growth. More sufficient healing time would be needed to recognize effects of dMSCs on bone formation.

Biomarkers for Bisphosphonate‐Related Osteonecrosis of the Jaw

PURPOSE The aim of this study was to investigate a possible biomarker for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in an animal model. MATERIALS AND METHODS Forty-eight Sprague-Dawley rats were randomly divided into the bisphosphonate group (n = 36), who were injected once a week with zoledronic acid, and the control group (n = 12), who were injected once a week with saline. After 6 weeks, surgical intervention was performed, and injections were continued up to 8 weeks. Rats in the bisphosphonate group were then further classified to the ONJ group, and the non-ONJ group, and biomarkers, including CTx, Glu-OC, TRACP 5b, RANKL, and OPG, were assessed at baseline (T0), at surgical intervention (T1), and at sacrifice (T2). Histomorphometric analysis for quantification of osteoclasts was performed. RESULTS Repeated measures analysis of variance revealed that TRACP 5b levels and the RANKL/OPG ratio were significantly decreased over time in the ONJ group compared with the non-ONJ group (p < .05). At T2, the area under the curve was 0.807 for TRACP 5b (sensitivity: 88.9%, specificity 66.7% at cutoff) and 0.765 for the RANKL/OPG ratio (sensitivity: 77.8%, specificity 62.9% at cutoff). TRACP 5b showed a lower least significant change (29.6%) with lower intra-assay coefficient of variability (CV; 6.32%) and interassay CV (11.20%) compared with those of the RANKL/OPG ratio (39.27%) and showed a higher signal-to-noise ratio (2.76) than that of the RANKL/OPG ratio (1.62). N.Oc/T.Ar and N.Oc/B.Ar demonstrated significantly decreased number of osteoclasts in ONJ group versus non-ONJ group. CONCLUSIONS These results show that serum TRACP 5b and the RANKL/OPG ratio were possible biomarkers for BRONJ. These data may provide useful additional information for future ONJ research. Further studies are needed to validate these results in humans with ONJ.

Social and physical environments and self-rated health in urban and rural communities in Korea

This study evaluated the associations between social and physical environments and self-rated health (SRH) for urban and rural Korean adults, using data from the Korean Community Health Survey (KCHS) of 199,790 participants (115,454 urban and 84,336 rural). The main dependent variable was SRH, while the primary independent variables were social and physical characteristics. Urban residents reported better SRH than did rural residents. Five social environmental variables (trust of neighbors, residence in the area for over 20 years, exchanging help with neighbors, friend and fellowship activities, contact with relatives and neighbors over five times per month) were more prevalent among rural residents. Satisfaction with physical environment was more common among rural residents, but satisfaction with traffic and healthcare facilities was more common among urban areas. After adjusting for relevant factors, positive associations between SRH and trust of neighbors, exchanging help with neighbors, participation in social activities or organizations, and physical environment existed in both rural and urban populations. Also, in both areas, there was no demonstrated association between SRH and years of residence or frequency of contact with relatives. Our findings suggest the existence of an association between social and physical factors and perceived health status among the general population of Korea.

Comparison of implant stability after different implant surface treatments in dog bone

Objectives The purpose of this investigation was to evaluate the effects of different implant surface treatments on implant stability in dog mandibles. Material and Methods A total of 30 implants (Dentium Co, Seoul, Korea) were placed in 5 dog mandibles. Bone quality was assessed at each site. Implant stability was evaluated using 2 different methods. An Osstell™ resonance frequency analyzer (RFA) was used to determine the stability at baseline (day 1), and 3, 6 and 10 weeks after surgery. Animals were euthanized 10 weeks after implant installation. Specimens were obtained and submitted to the laboratory processing. Sections were stained with hematoxylin and eosin for histologic and histomorphometric analyses. All implantation sites in dog mandibles demonstrated bone types II and III. Results and Conclusions All implants showed good primary stability at baseline in terms of insertion torque. The results of this study suggest that surface treatment may have significant effects on biological stability 3 weeks after implant placement. Further studies are needed to confirm these initial observations in poor quality bone.

The chamois component-based knowledge engineering framework

A prototype software framework and research testbed exploits recent findings in knowledge engineering to power an electronic commerce application. Chamois combines two main components. The infrastructure component consists of software products and prototype modules that provide key knowledge engineering technologies. The application component uses the infrastructure as a data and knowledge resource. We chose the primary application, an electronic commerce system, as our validation candidate because it includes various functional components that use the underlying knowledge engineering technology. These components include personalization, security, quality-of-service transmission of multimedia data, querying, and XML document management.

An e-learning framework supporting personalization and collaboration

Advances in Internet technology have made possible, rapid adoption of e-learning in many fields of society. Various educational methods for e-learning have been developed because personalization can be easily implemented through web services. However, these e-learning methods are not widely used because it is difficult for instructors to apply them in developing their courseware. Currently, the most widely used style of e-learning courseware is viewing video clips of lectures and discussing the lecture using bulletin boards. It is an electronic version of the traditional classroom. In this paper, we propose a user-friendly e-learning framework that supports personalization and collaboration between the instructor and the students. Instructors can create various levels of learning objects and define the relationships between the objects. Students can select the topics of their interest and dynamically adjust the level of learning in real time. Multiple instructors can cooperate in expanding the courseware. All the participants can also annotate the learning materials independently.

Efficient Multiple Aggregations of Stream Data

Recently there has been a great deal of interests in analyzing stream data that can be seen in applications such as network monitoring, web click stream analysis, and sensor networks. Multiple aggregations are regarded as one of the important operations for the high level analysis of stream data as well as business data. However, existing multiple aggregation algorithms for business data are not adequate for stream data because aggregation should be done on a rapidly flowing unsorted data stream, which requires tremendous amount of time and space. We propose an algorithm for efficiently generating user selected aggregation tables from unsorted data stream. For fast aggregation, we use a combination of arrays and AVL trees as temporary storage of aggregation tables. The proposed algorithm can also be used for the cases where aggregation tables are too large to be stored in main memory during aggregation. We showed by experiments that our algorithm is practical.

An Enterprise Security Management System as an ASP Solution

Advances in Internet technologies have enabled not only large corporations but also small/medium businesses to utilize the Internet for their businesses. While enterprises can be more competitive with such high-tech tools, they are now inevitably exposed to various security risks and threats. In order to protect their information assets, large corporations purchase and operate enterprise security management systems which provide enterprise-level integrated security. However, they are so expensive that small/medium businesses can hardly afford to utilize one. We hold that one way of providing integrated security to small/medium businesses in a costeffective manner is by means of an ASP solution. In this paper, we justify our proposition by analyzing the market trends for ASP in conjunction with security management software. We also propose a web-based security management system that can be used as an ASP solution. To the best of our knowledge, it is the first such system and is currently running as a commercial solution at a Korean ASP which provides services to 3,000 small/medium businesses.