Anticoccidial Effect of CS 32 Compounds Against Eimeria tenella Infection in Chickens

Coccidiosis-causing Eimeria species are transmitted in poultry via the oral-fecal route and can lead to hemorrhagic diarrhea and mortality. This results in enormous economic losses in the poultry industry. Furthermore, its resistance to some currently used antibiotics is increasing. This has prompted the development of new alternative drug therapies that address the issue of chemical-free meat production. Effective management of infectious diseases in veterinary practice includes the induction of protective and adaptive immunity by treatment with an alternative agent. In this study, we evaluated the anticoccidial effects of dietary supplementation of Chosun University (CS) 32 compounds (0.1% and 1.0%) against Eimeria tenella, which was isolated and purified from the supernatant of culture broth of Bacillus strain (KCTC18250P), as well as its effect on the growth rate and feed efficiency in chickens. Overall, we observed a decrease in lesion scores and oocyte output in CS 32 compounds-treated chickens. We concluded that 0.1% CS 32 compounds displayed anticoccidial effects against E. tenella infection.

Effects of three-dimensionally printed polycaprolactone/β-tricalcium phosphate scaffold on osteogenic differentiation of adipose tissue- and bone marrow-derived stem cells

BACKGROUND: Autogenous bone grafts have several limitations including donor-site problems and insufficient bone volume. To address these limitations, research on bone regeneration is being conducted actively. In this study, we investigate the effects of a three-dimensionally (3D) printed polycaprolactone (PCL)/tricalcium phosphate (TCP) scaffold on the osteogenic differentiation potential of adipose tissue-derived stem cells (ADSCs) and bone marrow-derived stem cells (BMSCs). METHODS: We investigated the extent of osteogenic differentiation on the first and tenth day and fourth week after cell culture. Cytotoxicity of the 3D printed PCL/β-TCP scaffold was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, prior to osteogenic differentiation analysis. ADSCs and BMSCs were divided into three groups: C, only cultured cells; M, cells cultured in the 3D printed PCL/β-TCP scaffold; D, cells cultured in the 3D printed PCL/β-TCP scaffold with a bone differentiation medium. Alkaline phosphatase (ALP) activity assay, von Kossa staining, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting were performed for comparative analysis. RESULTS: ALP assay and von Kossa staining revealed that group M had higher levels of osteogenic differentiation compared to group C. RT-PCR showed that gene expression was higher in group M than in group C, indicating that, compared to group C, osteogenic differentiation was more extensive in group M. Expression levels of proteins involved in ossification were higher in group M, as per the Western blotting results. CONCLUSION: Osteogenic differentiation was increased in mesenchymal stromal cells (MSCs) cultured in the 3D printed PCL/TCP scaffold compared to the control group. Osteogenic differentiation activity of MSCs cultured in the 3D printed PCL/TCP scaffold was lower than that of cells cultured on the scaffold in bone differentiation medium. Collectively, these results indicate that the 3D printed PCL/TCP scaffold promoted osteogenic differentiation of MSCs and may be widely used for bone tissue engineering.

Identification of Enterococcus faecalis antigens specifically expressed in vivo

OBJECTIVES: Molecular mechanism of the pathogenicity of Enterococcus faecalis (E. faecalis), a suspected endodontic pathogen, has not yet been adequately elucidated due to limited information on its virulence factors. Here we report the identification of in vivo expressed antigens of E. faecalis by using a novel immunoscreening technique called change-mediated antigen technology (CMAT) and an experimental animal model of endodontic infection. MATERIALS AND METHODS: Among 4,500 E. coli recombinant clones screened, 19 positive clones reacted reproducibly with hyperimmune sera obtained from rabbits immunized with E. faecalis cells isolated from an experimental endodontic infection. DNA sequences from 16 of these in vivo-induced (IVI) genes were determined. RESULTS: Identified protein antigens of E. faecalis included enzymes involved in housekeeping functions, copper resistance protein, putative outer membrane proteins, and proteins of unknown function. CONCLUSIONS: In vivo expressed antigens of E. faecalis could be identified by using a novel immune-screening technique CMAT and an experimental animal model of endodontic infection. Detailed analysis of these IVI genes will lead to a better understanding of the molecular mechanisms involved in the endodontic infection of E. faecalis.

Evaluation of short-term ex vivo culture with air/liquid system of porcine cornea / 동물의과학연구지

Regarding therapies for treatment of corneal wounds, ex vivo corneal culture is the most effective for minimizing expensive animal studies. Eighteen porcine enucleated eyes were soaked in 0.2% povidone iodine solution for disinfection prior to cornea excision. Subsequently, corneas were excised from whole eyes and filled with an agar/medium mixture. Corneas were transferred into culture dishes, after which culture medium was added until the limbus was covered. Cultures were then placed onto a plate rocker to mimic blinking action, followed by incubation at 37degrees C and 5% CO2. Corneas were harvested on Days 0, 3, and 7 after incubation, and optical coherence tomography (OCT) was performed on Day 7. Two eyes from each group were fixed in 2% glutaraldehyde/4% paraformaldehyde for low vacuum scanning electron microscopy (LV-SEM), and four eyes from each group were fixed in 10% neutral-buffered formalin for histological analysis. OCT results showed that central corneal thickness significantly increased by Day 7 compared to Day 0 (P<0.05). Using LV-SEM, gaps between endothelial cells were detected on Day 7 of ex vivo culture. In the histological evaluation, four to five stratified squamous cell layers, wing cells, and basal cells in the epithelium as well as flat-shaped keratocytes in the stroma were found on Day 0. By Day 7, stratified squamous cells and basal cells had decreased in number, and slightly round-shaped keratocytes were observed; however, the number of keratocytes was similar to that on Day 0. In this short-term ex vivo culture, epithelium and endothelium were sensitive to culture, whereas stroma and keratocytes were well maintained. An additional deswelling method will be needed to obtain more successful results in porcine corneal ex vivo culture.

The effect of bacterial cellulose membrane compared with collagen membrane on guided bone regeneration

PURPOSE: This study was to evaluate the effects of bacterial cellulose (BC) membranes as a barrier membrane on guided bone regeneration (GBR) in comparison with those of the resorbable collagen membranes. MATERIALS AND METHODS: BC membranes were fabricated using biomimetic technology. Surface properties were analyzed, Mechanical properties were measured, in vitro cell proliferation test were performed with NIH3T3 cells and in vivo study were performed with rat calvarial defect and histomorphometric analysis was done. The Mann-Whitney U test and the Wilcoxon signed rank test was used (alpha<.05). RESULTS: BC membrane showed significantly higher mechanical properties such as wet tensile strength than collagen membrane and represented a three-dimensional multilayered structure cross-linked by nano-fibers with 60 % porosity. In vitro study, cell adhesion and proliferation were observed on BC membrane. However, morphology of the cells was found to be less differentiated, and the cell proliferation rate was lower than those of the cells on collagen membrane. In vivo study, the grafted BC membrane did not induce inflammatory response, and maintained adequate space for bone regeneration. An amount of new bone formation in defect region loaded with BC membrane was significantly similar to that of collagen membrane application. CONCLUSION: BC membrane has potential to be used as a barrier membrane, and efficacy of the membrane on GBR is comparable to that of collagen membrane.

Effect of probiotic 379D as an alternative to antibiotics for feed supplementation in broiler chickens / 동물의과학연구지

Antibiotics have been used to prevent disease, promote growth rate, and improve feed efficiency. However, the use of antibiotics in livestock has been restricted worldwide due to problems such as bacterial resistance. Therefore, probiotics among alternatives to antibiotics have gained attention in the livestock feed industry these days. This study was conducted to investigate the effects of dietary supplementation with probiotic 379D on safety, growth rate, and feed efficiency. In this study, bacterial strain 379D was isolated from soil and identified as a Bacillus sp. according to 16S rRNA sequence analysis. In an in vitro test, in-gel activity assay and antimicrobial susceptibility test were conducted to evaluate 379D. In an in vivo study, 379D was administered at concentrations of 0.1% and 1% to broiler chickens for 28 days. The results of in-gel activity assay and antimicrobial susceptibility test showed that strain 379D had broad spectrum antimicrobial activity. Furthermore, no adverse 379D-related effects were observed in 0.1% and 1% groups. Feed efficiency was higher in the 379D-treated groups than in the control group. In conclusion, 379D is expected to be used as a safe alternative to antibiotics in a feed supplement and will improve feed efficiency in broiler chickens.

Evaluation of biocompatibility of alpha-1,3 galactosyltransferase knockout pig bone graft in a rat calvarial defect model / 동물의과학연구지

The current study was conducted to evaluate the biocompatibility of alpha-1,3 galactosyltransferase knockout pig bone graft in a rat calvarial defect model. Porcine cancellous bones were harvested from general and alpha-gal KO pigs and washed with 70% ethanol solution and normal saline. Bone pieces of the alpha-gal KO pig underwent a chemical treatment process to delipidize and deproteinize the bone. Bone graft particles were freeze-dried and stored at -70degrees C until use. Each bone graft was implanted into the rat calvarial defect in a fresh general pig, fresh transgenic pig, and chemical-treated pig bone group. There was no systemic adverse effect on hematology or necropsy findings in all groups at 1 week and 4 weeks. In the microcomputed tomography analysis, bone volume increased significantly in the chemical-treated transgenic pig bone group, whereas bone mineral density decreased significantly in the fresh general pig bone group compared with other groups. Histological evaluation showed cellular infiltration located at the margin of the bone graft particles, especially in the fresh general pig bone group. These results indicate that fresh general pig bone can elicit a greater local inflammatory response than fresh transgenic pig bone. Further, chemical-treated transgenic pig bone graft was less immunogenic than fresh bone graft. In conclusion, transgenic pig bone is a more biocompatible graft material. In addition, chemical treatment can reduce bone graft immunogenicity by delipidizing and deproteinizing bone.

Comparable bone healing capacity of different bone graft matrices in a rabbit segmental defect model

We compared the bone healing capacity of three different demineralized bone matrix (DBM) products applied using different carrier molecules (hyaluronic acid [HA] vs. carboxymethylcellulose [CMC]) or bone compositions (cortical bone vs. cortical bone and cancellous bone) in a rabbit segmental defect model. Overall, 15-mm segmental defects in the left and right radiuses were created in 36 New Zealand White rabbits and filled with HA-based demineralized cortical bone matrix (DBX), CMC-based demineralized cortical bone matrix (DB) or CMC-based demineralized cortical bone with cancellous bone (NDDB), and the wound area was evaluated at 4, 8, and 12 weeks post-implantation. DBX showed significantly lower radiopacity, bone volume fraction, and bone mineral density than DB and NDDB before implantation. However, bone healing score, bone volume fraction, bone mineral density, and residual bone area at 4, 8, and 12 weeks post-implantation revealed no significant differences in bone healing capacity. Overall, three DBM products with different carrier molecules or bone compositions showed similar bone healing capacity.

Protective effects of pine bark extract against cisplatin-induced hepatotoxicity and oxidative stress in rats / 한국실험동물학회지

We investigated the protective effects of pine bark extract (pycnogenol(R), PYC) against cisplatin-induced hepatotoxicity and oxidative stress in rats. Twenty-four male rats were divided into the following four groups: (1) vehicle control, (2) cisplatin (7.5 mg/kg), (3) cisplatin & PYC 10 (10 mg/kg/day), and (4) cisplatin & PYC 20 (20 mg/kg/day). A single intraperitoneal injection of cisplatin induced hepatotoxicity, as evidenced by an increase in serum aminotransferase and histopathological alterations, including degeneration/necrosis of hepatocytes, vacuolation, and sinusoidal dilation. In addition, an increase in the malondialdehyde (MDA) concentration and a decrease in the reduced glutathione (GSH) content and catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) activities were observed in the cisplatin-treated rat hepatic tissues. In contrast, PYC treatment effectively prevented cisplatin-induced hepatotoxicity, including the elevation of aminotransferase and histopathological lesions, in a dosedependent manner. Moreover, PYC treatment also induced antioxidant activity by decreasing MDA level and increasing GSH content and SOD and GST activities in liver tissues. These results indicate that PYC has a protective effect against acute hepatotoxicity induced by cisplatin in rats, and that the protective effects of PYC may be due to inhibiting lipid peroxidation and increasing antioxidant activity.

Effects of mesenchymal stem cells treated with BMP-2 and VEGF on regeneration of large bone defects / 동물의과학연구지

This study evaluated the possibility of clinical application using matrigel-based bioceramic/polymer scaffolds treated with bone morphogenetic protein, angiogenic factor, and mesenchymal stem cells (MSCs) for new bone formation. In the in vitro study, bone morphogenetic protein (BMP-2) and vascular endothelial growth factor (VEGF) containing matrigel, which is a basement membrane gel, was injected into HA/PCL scaffolds to estimate the release rates of growth factors. In the in vivo study, BMP-2, VEGF, and MSCs with matrigel-based scaffolds were implanted into rat femoral segmental defects, and new bone formation was evaluated at 4 and 8 weeks. In the results, the release rates of BMP-2 and VEGF explosively increased by day 5. For the in vivo study results, radiological evaluation revealed that the matrigel-based HA/PCL scaffolds with BMP-2 and VEGF grafted (M+B+V) and matrigel-based HA/PCL scaffolds with BMP-2, VEGF, and MSC grafted (MSC) groups showed increased bone volume and bone mineral density. Moreover, in the histological evaluation, large new bone formation was observed in the M+B+V group, and high cellularity in the scaffold was observed in the MSC group. In conclusion, grafted matrigel-based HA/PCL scaffolds with BMP-2, angiogenic factor, and MSCs increased new bone formation, and in clinical cases, it may be effective and useful to enhance healing of delayed fractures.

The effect of angiogenic factors with HA/PCL scaffold containing matrigel in a rat calvarial defect model / 동물의과학연구지

The current study was conducted in order to investigate bone formation using matrigel and angiogenic factors with HA and poly epsilon-caprolactone (HA/PCL) in a rat calvarial defect model. Calvarial defect formation was surgically created in Sprague Dawley rats (n=36). Rats in the control group (CD group, n=6) did not receive a graft. The HA/PCL scaffold was grafted with matrigel (M-HA/PCL group, n=6) or without matrigel (HA/PCL group, n=6); and 100 ng of vascular endothelial growth factor with HA/PCL scaffold containing matrigel (VEGF100 group, n=6), 100 ng (PDGF100 group, n=6) and 300 ng (PDGF300 group, n=6) of PDGF with HA/PCL scaffold containing matrigel were grafted in calvarial defects, respectively. Four weeks after surgery, bone formation was evaluated with micro computed tomography (micro CT) scanning, and histologically. According to the results, bone mineral density was significantly increased in the VEGF100, PDGF100, and PDGF300 groups compared to the HA/PCL group, in which angiogenic factors were not applied. In histological evaluation, more new bone formation around scaffolds was observed in the PDGF100 and the PDGF300 groups, compared with the VEGF100 group. Thus, the results indicate that HA/PCL containing matrigel with VEGF and PDGF is an effective grafting material for enhancement of bone formation in critical-sized bone defects. Especially, due to its price and capacity for bone formation, PDGF may be more effective than VEGF.

Efficacy of alcohol-free cetylpyridinium chloride on periodontal disease in beagle dogs via drinking water additive and oral gel / 동물의과학연구지

This study was conducted in order to examine the effects of alcohol-free cetylpyridinium chloride drinking water additive and oral gel on clinical parameters related to periodontal disease in beagle dogs. This study was conducted with healthy 15 beagle dogs. Following a professional teeth cleaning procedure, dogs were divided into three groups. Dogs in the control group received nothing, those in the drinking water additive (DWA) group received 800 ml water with 15 ml of alcohol-free cetylpyridinium chloride drinking water additive daily, and those in the Oral gel (OG) group were treated with oral gel containing alcohol-free cetylpyridinium chloride and 0.05% chlorhexidine gluconate daily. Clinical parameters, including plaque index (PI), calculus index (CI), and gingivitis index (GI) were evaluated at two and four weeks. Dogs in the DWA and OG groups had significantly less plaque than dogs in the control group at two and four weeks (P<0.01, P<0.05). And, at four weeks, CI was significantly lower in the OG group compared to the control group (P<0.05). On GI, similar scores were recorded for all groups during the experimental period. No significant difference was observed between the DWA group and the OG group. The effect of alcohol-free cetylpyridinium chloride drinking water additive was similar to the result for alcohol containing cetylpyridinium chloride mouthwash reported in a previous study. The effect in control of periodontal disease was better in the OG group because of additional chlorhexidine gluconate. However, use of drinking water additive will be more convenient for owners; thus, it will be more effective for achievement of long-term results.

Effects of probiotic CS-32 as a feed additive on growth performance of broiler chickens / 동물의과학연구지

In the livestock feed industry, antibiotics are used to prevent disease, promote growth rate, and improve feed efficiency. However, antibiotic supplementation to animal feed results in increased bacterial resistance to antibiotics as well as antibiotic residues in animal products, which can negatively affect human health. Therefore, alternative sources of antibiotics are needed. Probiotics as an alternative to antibiotics in animal feed have been shown to increase feed efficiency and growth rate by improving microbial balance. Further, Bacillus sp. produces a wide spectrum of antibacterial peptides. The present study was conducted to investigate the effects of dietary supplementation with CS-32 on safety, growth rate, and feed efficiency. Antibacterial substance (5697.9 molecular weights) produced by CS-32 was isolated and purified from culture broth. Moreover, the results of minimal inhibitory concentration (MIC) test confirmed the excellent antibacterial effect of CS-32. In vivo, 0.1% and 1% CS-32 were fed to broiler chickens for 28 days. Feed efficiency was slightly higher in groups of chickens supplemented with 0.1% and 1% CS-32 than those of the control group. CS-32 had no significant effect on necropsy findings, hematology, or serum biochemistry, and there was no mortality. These results suggest that CS-32 among various biologically active substances may be safe and effective as a feed additive to improve growth rate and feed efficiency.

The Feasibility of Lateral Minimal Invasive Open Thyroid Lobectomy / 대한내분비외과학회지

PURPOSE: Minimal invasive open thyroidectomy is one option for minimal invasive surgery. The population of planned unilateral lobectomy is on the rise in parallel to the increased incidence of confined papillary thyroid microcarcinomas in Korea. In contrast to other minimal invasive modalities, few studies have examined the surgical outcome of minimal invasive open thyroidectomy. This study compared the lateral minimal invasive open thyroid lobectomy with conventional surgery and endoscopic surgery in terms of the feasibility and safety. METHODS: A retrospective study was performed on 197 patients undergoing a thyroid lobectomy between January 2001 and December 2010. One hundred and three patients underwent a lateral minimal invasive open thyroid lobectomy, 42 patients underwent conventional surgery, and 44 patients underwent endoscopic surgery. RESULTS: The hospitalization period with endoscopic surgery was 6.2 days, which was longer than the 5.3 days with a lateral minimal invasive open thyroid lobectomy (P=0.000). The surgical time was lower in those who underwent a lateral minimal invasive open thyroid lobectomy (88.2 minutes) than in those who underwent conventional surgery (107 minutes, P=0.000) or endoscopic surgery (124.1 minutes, P=0.000). In the patients with a diagnosis of malignancy, the mean number of retrieved LNs was similar in the three groups. CONCLUSION: A lateral minimal invasive open thyroid lobectomy offers advantages, such as a shorter surgical time and hospitalization period than others. This procedure can be a feasible alternative to the conventional or endoscopic approach in selected patients undergoing thyroid lobectomy.

The effect of platelet rich plasma in bone formation on implant installation in the tibia of beagle dogs

INTRODUCTION: The purpose of this study is to evaluate the effect of platelet rich plasma in bone formation and osseointegration of implant installed in the bone marrow space. MATERIALS AND METHODS: Five beagle dogs were used as experimental animals. Two implants were installed on each tibia in the dogs. Implants of the control group were installed with no additional graft. Those of the experimental group 1 were installed with autogenous bone graft from the ilium autogenous bone. Platelet rich plasma (PRP) alone was used in experimental group 2 and the mixture of PRP and autogenous bone was used in experimental group 3. The animals were sacrificed at 8 weeks after implantation. The parts of tibia containing implant were harvested and radiographs were taken for radiographic examination. The specimens were prepared for histological examination and histomorphometric analysis of implant-bone contact ratios. RESULTS: 1. All implants showed sufficient osseointegration in the cortical bone radiographically and histologically, but osseointergration in the marrow space was not satisfactory. 2. Histomorphometrically, the implant-bone contact ratios in the bone marrow was sequentially high in the experimental group 3 (autogenous bone + PRP group), group 1 (autogenous bone group), group 2 (PRP group), and control group (non-additive). 3. It was verified that there was statistical significance between two experimental groups (group 1 and 3) and the other groups (group 2 and control group). (P<0.005) 4. However, there was no statistical significance between group 3 and group 1, also group 2 and control group respectively. CONCLUSION: These results suggest that platelet rich plasma is effective to osseointegration in the implant installation but there is no statistical significance.

Tissue Specific Expression of Lipid Metabolism Related Molecules in Digestive Organs of Miniature Pigs / 한국실험동물학회지

The miniature pig is a very suitable donor species in xenotransplantation of human organs. Lipid metabolism is an important process that involves the creation and degradation of lipids, which is associated with the function of the gastro-intestinal tract. However, the distribution of lipid metabolism related molecules in the gastro-intestinal tract in the miniature pig is unclear. The present study examined the expression of farnesoid X-receptor (FXR), liver X- receptor (LXR), retinoid X-receptor (RXR), liver fatty acid binding protein (L-FABP), fatty acid synthase (FAS) mRNA in the digestive organs of miniature pigs. FXR and LXR mRNA were not expressed in the stomach but were expressed at high and low density in the small and large intestines, respectively. RXR mRNA was expressed in stomach with moderate density, small intestine with high density and in the large intestine with low density. L-FABP and FAS mRNA were expressed in the stomach and large intestine with low density and in the small intestine with high density. L-FABP mRNA was expressed in the liver and kidney with high density, and in pancreas with low density. FAS mRNA was expressed in the liver with high density, and in pancreas and kidney with low density.

Tissue Specific Expression of Lipid Metabolism Related Molecules in Digestive Organs of Miniature Pigs / 한국실험동물학회지

The miniature pig is a very suitable donor species in xenotransplantation of human organs. Lipid metabolism is an important process that involves the creation and degradation of lipids, which is associated with the function of the gastro-intestinal tract. However, the distribution of lipid metabolism related molecules in the gastro-intestinal tract in the miniature pig is unclear. The present study examined the expression of farnesoid X-receptor (FXR), liver X- receptor (LXR), retinoid X-receptor (RXR), liver fatty acid binding protein (L-FABP), fatty acid synthase (FAS) mRNA in the digestive organs of miniature pigs. FXR and LXR mRNA were not expressed in the stomach but were expressed at high and low density in the small and large intestines, respectively. RXR mRNA was expressed in stomach with moderate density, small intestine with high density and in the large intestine with low density. L-FABP and FAS mRNA were expressed in the stomach and large intestine with low density and in the small intestine with high density. L-FABP mRNA was expressed in the liver and kidney with high density, and in pancreas with low density. FAS mRNA was expressed in the liver with high density, and in pancreas and kidney with low density.

Scintigraphic Assessment of Renal Function Using 99mTc-DTPA in Miniature Pigs with Unilateral Ureteral Obstruction / 한국실험동물학회지

This study was performed to investigate the proper method for evaluating renal function in miniature pigs with unilateral ureteral obstruction. Experimental unilateral renal damage was induced after ligation of unilateral right ureter in 3 miniature pigs. On the 3rd post-operative day, scintigraphic images were obtained after 12 mCi of 99mTc-diethylentriamene pertaacetate (DTPA) intravenous injection. Renography showed that radiopharmaceutical uptakes in the right kidney were lower than those of left kidney uptakes as early as at 3 days after surgical operation. The static images of 99mTc-DTPA enabled us to measure the relative renal function in miniature pigs with unilateral ureteral obstruction. In conclusion, renography using 99mTc-DTPA was the useful diagnostic method to evaluate the renal function in miniature pigs.

The pattern of movement and stress distribution during retraction of maxillary incisors using a 3-D finite element method / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate the displacement pattern and the stress distribution shown on a finite element model 3-D visualization of a dry human skull using CT during the retraction of upper anterior teeth. METHODS: Experimental groups were differentiated into 8 groups according to corticotomy, anchorage (buccal: mini implant between the maxillary second premolar and first molar and second premolar reinforced with a mini implant, palatal: mini implant between the maxillary first molar and second molar and mini implant on the midpalatal suture) and force application point (use of a power arm or not). RESULTS: In cases where anterior teeth were retracted by a conventional T-loop arch wire, the anterior teeth tipped more postero-inferiorly and the posterior teeth moved slightly in a mesial direction. In cases where anterior teeth were retracted with corticotomy, the stress at the anterior bone segment was distributed widely and showed a smaller degree of tipping movement of the anterior teeth, but with a greater amount of displacement. In cases where anterior teeth were retracted from the buccal side with force applied to the mini implant placed between the maxillary second premolar and the first molar to the canine power arm, it showed that a smaller degree of tipping movement was generated than when force was applied to the second premolar reinforced with a mini implant from the canine bracket. In cases where anterior teeth were retracted from the palatal side with force applied to the mini implant on the midpalatal suture, it resulted in a greater degree of tipping movement than when force was applied to the mini implant between the maxillary first and second molars. CONCLUSION: The results of this study verifies the effects of corticotomies and the effects of controlling orthodontic force vectors during tooth movement.

A case of maloccluded incisor teeth in a beaver: Castor canadensis

A three-year-old female beaver (Castor canadensis) was referred to the Veterinary Teaching Hospital of Chungbuk National University. It had been raised in the Cheong-ju zoo and had a history of malocclusion caused by improper feeding. General anesthesia was induced, and preoperative intraoral dental radiographs of the rostal maxillary and mandibular dentition were taken and lateral and ventrodorsal extraoral radiographs of the cheek teeth were also taken. The radiographs were negative for apical pathology and revealed a normal appearance of the cheek teeth. The lesion was likely to be related to the excessive length of the maxillary and mandibular incisors. Odontoplasty was performed to reduce overgrowth of the crowns of the incisors. Sequential transverse sections were removed until the crown was reduced by approximately its original length. The pulp chamber was not approached during the operation, as confirmed by postoperative intraoral radiographic evaluation of the incisors. Recovery from anesthesia was uneventful and the beaver returned to normal masticatory activities immediately after the operation.