Bone cement grafting increases implant primary stability in circumferential cortical bone defects

PURPOSE: Implant beds with an insufficient amount of cortical bone or a loss of cortical bone can result in the initial instability of a dental implant. Thus, the objective of this study was to evaluate the effect of bone cement grafting on implant initial stability in areas with insufficient cortical bone. METHODS: Two different circumferential defect depths (2.5 mm and 5 mm) and a control (no defect) were prepared in six bovine rib bones. Fourteen implants of the same type and size (4 mm x 10 mm) were placed in each group. The thickness of the cortical bone was measured for each defect. After the implant stability quotient (ISQ) values were measured three times in four different directions, bone cement was grafted to increase the primary stability of the otherwise unstable implant. After grafting, the ISQ values were measured again. RESULTS: As defect depth increased, the ISQ value decreased. In the controls, the ISQ value was 85.45+/-3.36 (mean+/-standard deviation). In circumferential 2.5-mm and 5-mm defect groups, the ISQ values were 69.42+/-7.06 and 57.43+/-6.87, respectively, before grafting. These three values were significantly different (P<0.001). After grafting the bone cement, the ISQ values significantly increased to 73.72+/-8.00 and 67.88+/-10.09 in the 2.5-mm and 5.0-mm defect groups, respectively (P<0.05 and P<0.001). The ISQ value increased to more than double that before grafting in the circumferential 5-mm defect group. The ISQ values did not significantly differ when measured in any of the four directions. CONCLUSIONS: The use of bone cement remarkably increased the stability of the implant that otherwise had an insufficient level of stability at placement, which was caused by insufficient cortical bone volume.

Location of maxillary intraosseous vascular anastomosis based on the tooth position and height of the residual alveolar bone: computed tomographic analysis

PURPOSE: The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. METHODS: Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,8 mm. RESULTS: The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. CONCLUSIONS: Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation.

The effect of peri-implant bone exposure on soft tissue healing and bone loss in two adjacent implants

PURPOSE: The purpose of this study was to evaluate the soft tissue and bone change around two adjacent implants in one-stage implant surgery. METHODS: Eleven subjects (7 males, 4 females) who were needed placement of 2 adjacent implants in the molar area were included. The two implants were placed with the platform at the level of the alveolar crest. The interproximal bone between the 2 implants was not covered with gingiva. After surgery, an alginate impression was taken to record the gingival shape and radiographs were taken to evaluate implant placement. Using a master cast, the gingival height was measured at baseline, 4 weeks, and 12 weeks. In the radiograph, the alveolar bone level was measured at the mesial and distal side of both implants at baseline and 12 weeks. RESULTS: The exposed bone was covered with gingiva at both 4 and 12 weeks. Loss of alveolar bone around implants was found in all areas. The alveolar bone level in the exposed bone area did not differ from that in the non-exposed area. CONCLUSIONS: This study showed that the alveolar bone level and gingival height around 2 adjacent implants in the exposed bone area did not differ from that in unexposed bone area.

Spontaneous Spinal Epidural Hematomas Associated With Acute Myocardial Infarction Treatment

Many studies have reported spontaneous spinal epidural hematoma (SSEH). Although most cases are idiopathic, several are associated with thrombolytic therapy or anticoagulants. We report a case of SSEH coincident with acute myocardial infarction (AMI), which caused serious neurological deficits. A 56 year old man presented with chest pain accompanied with back and neck pain, which was regarded as an atypical symptom of AMI. He was treated with nitroglycerin, aspirin, low molecular weight heparin, and clopidogrel. A spinal magnetic resonance image taken after paraplegia developed 3 days after the initial symptoms revealed an epidural hematoma at the cervical and thoracolumbar spine. Despite emergent decompressive surgery, paraplegia has not improved 7 months after surgery. A SSEH should be considered when patients complain of abrupt, strong, and non-traumatic back and neck pain, particularly if they have no spinal pain history.

The effect of non-resorbable barrier membrane on the change of buccal and lingual alveolar bone in immediate implant placement into periapically infected extraction sockets / 대한치주과학회지

PURPOSE: Many researches showed loss of alveolar bone in fresh extraction socket and even in case of immediate implant placement. The aim of this study was to evaluate the effect of non-resorbable barrier membrane on the change of buccal and lingual alveolar bone in immediate implant placement into periapically infected extraction sockets. MATERIALS AND METHODS: Immediate implants were placed into artificially induced periapical lesion of mandibular premolars after complete debridement using buccal bone defect made by a 6mm trephine bur in 4 mongrel dogs. Before flap repositioning, a non-resorbable barrier membrane was placed on the buccal defect in the experimental group. No membrane was placed in the control group. In 12 weeks after placement, the dogs were sacrificed and undecalcified histologic specimens were prepared. The vertical distance from the smooth-rough surface interface(SRI) to gingiva, 1st bone contact and bone crest were measured in buccal and lingual side. The horizontal thicknesses of gingiva and bone at 0, 1, 2 and 3 mm below SRI were measured. RESULTS: The buccal bone was resorbed more than lingual bone in both groups and there was statistical significance(p<0.05). The distances from SRI to 1st bone contact were 2.45+/-2.35 mm in experimental group and 4.49+/-3.10 mm in control group. In all vertical level, lingual bone was thicker than buccal bone(p<0.05). CONCLUSION: Buccal bone was reduced more than lingual bone in immediate implant placement into periapically infected extraction sockets. Placement of non-resorbable barrier membrane reduced the buccal bone resorption. However there was no statistical significance.

Maxillary sinus floor augmentation with anorganic bovine bone: Histologic evaluation in humans / 대한치주과학회지

PURPOSE: The aim of this report is to investigate the efficacy of anorganic bovine bone xenograft(Bio-Oss(R) ) at maxillary sinus floor augmentation. MATERIALS AND METHODS: Two male patients who missed maxillary posterior teeth were included. They were performed maxillary sinus floor augmentation using anorganic bovine bone xenograft(Bio-Oss(R) ). After 10 or 13 months, the regenerated tissues were harvested using trephine drills with 2 or 4mm diameter and non-decalcified specimens were made. The specimens were examined histologically and histomorphometrically to investigate graft resorption and new bone formation. RESULTS: Newly formed bone was in contact with Bio-Oss(R) particles directly without any gap between the bone and the particles. The proportions of newly formed bone were 23.4~25.3% in patient 1(Pt.1) and 28.8% in patient 2(Pt.2). And the proportions of remained Bio-Oss(R) were 29.7~30.2% in Pt.1 and 29.2% in Pt.2. The fixtures installed at augmented area showed good stability and the augmented bone height was maintained well. CONCLUSION: Anorganic bovine bone xenograft(Bio-Oss(R) ) has high osteoconductivity and helps new bone formation, so that it can be used in maxillary sinus floor augmentation.

The effect of chlorhexidine on reduction of viable organisms in aerosol produced by ultrasonic scaler / 대한치주과학회지

PURPOSE: The aerosol generated by ultrasonic scaler can contain bacteria or virus which can penetrate into body through respiratory systems of dentists, dental hygienist or patients. The aim of this study is to evaluate the effect of chlorhexidine digluconate as preoperative mouthrinse or lavage for ultrasonic scaler on the reduction of viable organisms in aerosol produced during periodontal treatment using ultrasonic scaler. METHODS: 30 patients with moderate chronic periodontitis were included and divided into 3 groups: Control (no preoperative mouthrinse and tap water as lavage), CHG (preoperative mouthrinse with 0.1% chlorhexidine digluconate and tap water as lavage), CHL (no reoperative mouthrinse and 0.1% chlorhexidine digluconate as lavage). Each patient received scaling or subgingival curettage for 30 min. In CHG group, mouthrinse with chlorhexidine digluconate was performed for 1 min. before treatment. Before, during and after scaling or subgingival curettage, air sampling was performed for 7 min. each (1000 L/7 min.) with trypticase-soy agar plate. Agar plates were incubated in 37degrees C aerobically. The numbers of colony-forming units (CFU) were counted and compared. RESULTS: The numbers of CFUs of the samples obtained during treatment were 97+/-14.0 in control, 73.1+/-14.9 in CHG group and 44.5+/-9.0 in CHL group. The difference among the 3 groups was determined to be statistically significant (one-way ANOVA with Bonferroni's correction, p-value: 0.0003). In contrast, the numbers of CFU of samples obtained before and after treatment were not significantly different among the groups. CONCLUSIONS: Chlorhexidine digluconate used as preoperative mouthrinse or lavage for ultrasonic scaler can reduce the microorganisms in aerosol produced during periodontal treatment using ultrasonic scaler. Less number of microorganisms were detected when chlorhexidine was used as lavage for ultrasonic scaler.

The effect of implant drilling speed on the composition of particle collected during site preparation / 대한치주과학회지

PURPOSE: This study was aimed to evaluate the effect of implant drilling speed on the composition of particle size of collected bone debris. METHODS: Branemark System (R)drills were used to collect bone debris from 10 drilling holes (1 unit) at 1,500 rpm (Group A) and 800 rpm (Group B) in bovine mandible. After separating particles by size into > 500 microm, between 250 microm and 500 microm, and 500 microm fractions, Group B had significantly higher wet volume % (P = 0.0059) and dry volume % (P = 0.0272) than in Group A. CONCLUSIONS: The drilling speed influenced the composition of particle size in collected drilling bone debris. The drilling in 800 rpm produced the more percentage of large particles than in 1,500 rpm. However, the drilling speed didn't effect on total volume of and weight of bone debris.

Fluorescent detection of bacteria associated with gingival sulcus epithelium / 대한치주과학회지

PURPOSE: The aim of this study was to compare the number of live and dead bacteria attached to, or within, the stratified squamous epithelium lining the tissue side of the gingival sulcus. MATERIALS AND METHODS: A total of 50 patients was examined and classified into healthy or diseased sites according to inflammatory status of the gingival tissue. The surface of stratified squamous epithelium was removed by gentle scraping of the gingival sulcus with curettes. The cells were processed in the laboratory by density-gradient centrifugation to separate the epithelial cells from the loose bacteria and debris. The LIVE/DEAD(R) BacLight(TM) Bacterial Viability Kit was applied and the specimens were observed by an epifluorescent microscope and the number of bacteria was counted. RESULTS: Live and dead bacteria were stained to green and red, irrespectively. Generally, the number of total bacteria in the diseased sites was significantly higher than in the healthy sites. The mean number of detected bacteria in the diseased sites was 58.6+/-36.0 (red bacteria 10.4+/-9.2 / green bacteria 48.2+/-30.5), while it was 1.5+/-1.7 in the healthy sites (red bacteria 0.1+/-0.3 / green bacteria 1.4+/-1.5). The percentage of red bacteria was 17.5+/-11.2% in the diseased sites and 2.0+/-5.8% in the healthy sites. CONCLUSION: The total number of bacteria in the diseased sites was significantly higher than that of the healthy sites. The ratio and the number of red bacteria were also significantly higher in the diseased sites.

Effect of resorbable membrane on immediate placement of implant in extraction socket during periradicular surgery / 대한치주과학회지

PURPOSE: The guided bone regeneration (GBR) technique is widely used in periradicular surgery. However, there is still some controversy regarding the effectiveness of GBR in promoting bone healing after periradicular surgery. The purpose of this study was to evaluate the resorbable membrane on the osteointegration of immediate implants in sites with periradicular lesion that had been removed by periradicular surgery. MATERIALS AND METHODS: Six roots of lower second premolars and 15 roots of lower third and fourth premolars of dogs were used as control and experimental teeth, respectively. Periradicular lesions were induced only in the experimental teeth. Twelve weeks later, the control and experimental teeth were extracted and implants were placed immediately. Periradicular lesions were removed with osteotomy, curettage and saline irrigation. Resorbable membranes were used in experimental group 1 but not in experimental group 2. After 12 week of healing period, the implants were clinically not mobile and showed no signs of infection. Data obtained by histomorphometric analysis were analyzed by Kruskal-Wallis test. RESULTS: The control group showed a significantly higher bone to implant contact (BIC) (74.14+/-16.18) than experimental group 1 (40.28+/-15.96) and 2 (48.70+/-17.75)(p<0.05). However, there was no significant difference between experimental group 1 and 2. CONCLUSION: Although BIC in experimental groups were lower than in control group, immediate implant can be successfully placed at extraction socket with periradicular lesion and osseous defect. However, the use of resorbable membrane in bony defect created during periradicular surgery was questioned.

A 3 year-retrospective study of survival rate in single Branemark TiUnite(TM) implant / 대한치주과학회지

BACKGROUND: TiUnite(TM) is a highly crystalline and phosphate enriched titanium oxide surface which has a unique porous surface structure. This improved implant surface enhances bone response and reduces healing period. It also assures early stability of implant. These help to increase the success of implant. The aim o f this s tudy i s to e valuate the survival r ate of TiUnite TM surfaced single implant. MATERIALS AND METHODS: A retrospective analysis of 89 TiUnite(TM) surfaced implants replacing a single tooth was assessed according to their dental record. The age of the patients ranged from 17 to 82 years (mean age: 45.8 +/- 14.6). Data were recorded regarding the survival rate of these implants. RESULTS: Fifty-two implants (57%) were placed in the maxilla, and 37 (43%) in the mandible. Over 75% were placed in the posterior area. Of the placed implants, 67% were the wide type, while 25% were the regular type and only 8% were of the narrow type. The single implants produced an overall clinical survival rate of 96.6% over the observation period (mean 17.9 months). Among 89 implants, only 2 implants were removed and one implant was submerged. CONCLUSION: According to t he se data, TiUnite(TM) surfaced implant in a single tooth restoration showed favorable survival rate although this study was done in a short term period.

Incidence of sinus septa and accuracy of panoramic radiograph

PURPOSE: The purpose of this study was to determine the incidence of antral septa and the accuracy of panoramic radiograph in identifying maxillary sinus septa. In addition, when panoramic radiograph led to a false diagnosis of more than majority, we analyzed findings of the panoramic radiograph. PATIENTS AND METHODS: This study included 180 patients who were radiographically examined before the surgery was done using both panoramic and computerized tomographic radiographs(CT scan), Samsung Medical Center from April 2003 to March 2006, and examined the incidence of antral septa, the false diagnosis rate of panoramic radiograph, and radiographic characters in case of false diagnosis. Only those bone lamellae were considered as septa that showed a height of at least 3.0mm. It was thus possible to exclude the alveolar recess. One oral and maxillofacial surgeon(OMFS) determined the presence or absence of sinus septa in CT scan, and five OMFS determined the presence or absence of sinus septa in panoramic radiograph. RESULTS: The septa were observed in 81 of 360 sinuses(22.5%). All septa were oriented in a buccopalatal plane. More or less greater prevalence was observed in the second molar region(38.2%) but no predominant location was found. Panoramic radiograph led to false diagnosed septa in 361 of 1800 cases(20.1%). In case of false diagnosis of more than majority, superimposed image on zygomatic process was 44.1%, faint image in the region not related to sinus lifting 26.5%, faint image in the region related to sinus lifting 17.6%, and misconception for superimposed image 11.8% CONCLUSION: In this study we could get clinico-anatomical information of septum in the maxillary sinus. Compared to CT scan, panoramic radiograph can not clearly differentiate the sinus septa, but we consider that panoramic radiograph may improve its usefulness if we take additional modified panoramic radiograph and clinical exam.

Effect of cleansing me thods on the bone re sorption due to repeated dis/re-connection of implant abutment / 대한치주과학회지

BACKGROUND: Repeated dis/re-connection of implant abutment caused bone loss around implant fixtures due to the new formation of biologic width of the mucosal-implant barrier. The aim of this clinical study was to evaluate whether the repeated dis/re-connection of implant abutment cause bone loss clinically and the effect of cleansing methods on a bone loss during the early healing period. METHODS: A total 50 implants were installed in 20 patients and repeated dis/re-connection of abutment was performed at the time of surgery and once per week for 12 weeks. 0.9% normal saline solution as group1 and 0.1% chlorhexidine solution as group 2 was used to clean abutments. All patients had radiographs taken at the placement of implant and 4, 8, and 12 weeks postoperatively. The data for bone loss around implant were analyzed. RESULTS: The marginal bone loss at 12 weeks were 1.28+/-0.51mm, 1.32+/-0.57mm in the mesial and distal sides in group1, 1.94+/-0.75mm, 1.81+/-0.84mm in group 2, respectively. In view of marginal bone loss, there was not a significant statistical difference between groups. CONCLUSIONS: Repeated dis/re-connection of implant abutment may not cause marginal bone loss around implant fixture although limited samples and short-term observation period. In spite of more bone loss in group 2, there was no statistical significant difference between groups. In context of those results, the clinical significance of the repeated dis/re-connection of implant abutment and the cleansing method of abutments is debatable when it comes to marginal bone loss during early healing period.

The role of CD14 and Toll-like receptors on the release of MMP-8 in the LPS recognition pathway / 대한치주과학회지

No abstract available.

Effect of CD14, Toll-like receptors, cytoskeletal inhibitors and NF-kappaB inhibitor on MMP-8 release from human neutrophils induced by E. coli lipopolysaccharides / 대한치주과학회지

OBJECTIVE: MMP-8 is a neutrophil enzyme and its level increases in some inflammatory diseases, including periodontal disease. We knew that the lipopolysaccharide of E.coli(E-LPS) induced MMP-8 release from human neutrophils. E-LPS is known to induce the production and release of inflammatory cytokines through CD14, Toll-like receptor(TLR). In the present study, we investigated whether MMP-8 release by E-LPS is induced via CD14-TLR pathway and the cellular mechanism of MMP-8 release in human neutrophils. MATERIAL AND METHODS: Human neutrophils were isolated from the peripheral blood of healthy donors and pre-incubated in medium containing antibodies against CD14, anti-TLR2 and anti-TLR4 or several inhibitors of microtubules and microfilaments and then incubated with E-LPS. The cells were treated TPCK and E-LPS simultaneously. The MMP-8amount in the culture medium was determined using ELISA. RESULTS: E-LPS increased MMP-8release from neutrophils and its induction was inhibited by anti- CD14 and anti-TLR4 but not by anti-TLR2 antibodies. The inhibitors of micro- tubule and microfilament polymerization significantly decreased E-LPS-induced MMP- 8release. TPCK inhibited E-LPS-induced MMP-8 release. CONCLUSION: These results suggest that MMP-8 release is induced by E-LPS via the CD14-TLR4 signal pathway in human neutrophils and may be depedent on microtubule and microfilament systems and NF-kappaB pathway.

Biological Activities of HA-coated Zirconia / 대한치주과학회지

Hydroxyapatite(HA) has been extensively used as bone graft materials and tooth implant surface coating materials because of its biocompatibility and osteoconductive properties. However, as HA is intrinsically poor in mechanical properties, zirconia(ZrO2) was incorporated with HA as reinforcing phases for improvement of mechanical properties. The purpose of this study was to investigate the biological activities of HA-coated zirconia through the cell proliferation test, measurements of alkaline phosphatase activity, and histologic examination. Four kinds of tested blocks were prepared according to the pore size (300-500micrometer/500-700micrometer) and the porosity (70%/90%). Cell proliferation and alkaline phosphatase activity was measured at 1, 7, 14 days. The number of cells proliferate after 7, 14 days were significantly increased in all groups when compared with that of the first day, but there was no significant difference between the 4 groups at each time period. At the 7 day, alkaline phosphatase activities of cells cultured in 4 groups were higher than that of the first day, but there was no significant difference between the 4 groups at each time period. The human gingival fibroblast and MG 63 cell was used to evaluate the cell cytotoxicity using MTT test. The materials tested in the current study turned out to be non-cytotoxic. In histologic examination(SEM), at 1 day there were many cells attached on the surfaces of all kinds of tested blocks. The number of cells were increased over time. At the 14 day, there were more cells proliferated than 1 day and some of the pores of blocks were partially filled with the proliferated cells. The in vitro response of osteoblast-like cells to the HA-coated zirconia showed comparable effect on transformation comparable to hydroxyapatite.

The effect of calcium metaphosphate bone graft materials on bone regeneration / 대한치주과학회지

Periodontal regeneration therapy with bone-substituting materials has gained favorable clinical efficacy by enhancing osseous regeneration in periodontal bony defect. As bone- substituting materials, bone powder, calcium phosphate ceramic, modified forms of hydroxyapatite, and hard tissue replacement polymer have demonstrated their periodontal bony regenerative potency. Bone-substituting materials should fulfill several requirements such as biocompatibility, osteogenecity, malleability, biodegradability. The purpose of this study was to investigate biocompatibility, osteo-conduction capacity and biodegradability of Na2O, K2O added calcium metaphosphate(CMP). Beta CMP was obtained by thermal treatment of anhydrous Ca2(H2PO4)2. Na2O and K2O were added to CMP. The change of weight of pure CMP, Na2O-CMP, and K2O-CMP in Tris-buffer solution and simulated body fluid for 30 days was measured. Twenty four Newzealand white rabbits were used in negative control, positive control(Bio-Oss), pure CMP group, 5% Na2-CMP group, 10% Na2O-CMP goup, and 5% K2O-CMP group. In each group, graft materials were placed in right and left parietal bone defects(diameter 10mm) of rabbit. The animals were sacrificed at 3 months and 6 months after implantation of the graft materials. Degree of biodegradability of K2O or Na2O added CMP was greater than that of pure CMP in experimental condition. All experimental sites were healed with no clinical evidence of inflammatory response to all CMP implants. Histologic observations revealed that all CMP grafts were very biocompatible and osseous conductive, and that in K2O-CMP or Na2O-CMP implanted sites, there was biodegradable pattern, and that in site of new bone formation, there was no significant difference between all CMP group and DPBB(Bio-Oss) group. From this result, it was suggested that all experimental CMP group graft materials were able to use as an available bone substitution.

Histologic evaluation of Regenafil(TM) on defects of extraction socket / 대한치주과학회지

The purpose of this study is to evaluate histologic result of bone substituting material on defects followed tooth extraction. We compare the histologic findings control, DFDBA, Bio-Oss(R), and Regenafil(TM), Briefly, mandibular premolar teeth were extracted available for bone filling. All alveolar sites were checked after extraction and thoroughly debrided with a dental curet to remove the periodontal ligament. Extraction sites were prepared dehiscence on buccal side 7mm height from alveolar crest. The graft materials were filled into the extraction socket and dehiscenc defects. The animals were sacrificed 12 weeks after implantation. Both treated and control mandibular sites were histologically evaluated with light microscopy. Histologic observation at 12 weeks revealed that control and experimental sites were healed uneventfully and directly apposed to new bone without any adverse tissue reaction. DFDBA and Bio-Oss(R) sites maintain width of alveolar crest but were not fully resorbed. Regenafil(TM) sites also maintain width and particles were resorbed more than other graft materials. From this results, it was suggested that Regenafil(TM) is promising boen substituting materials maintaining the width of alveolar crest and height follewed tooth extraction.

Effects of enamel matrix derivative and titanium on the proliferation and differentiation of osteoblasts / 대한치주과학회지

Among objectives of periodontal therapy, the principal one is the morphological and functional reconstruction of lost periodontal supporting tissues. This includes de novo formation of connective tissue attachment and the regrowth of alveolar bone. The use of enamel matrix derivative(EMD) may be a suitable means of regeneration new periodontal attachment in the infrabony defects. Implant used to replace lost tooth but, implantitis occurred after installation. The purpose of this study was to investigate the effects of EMD on differentiation and growth of osteoblast in titanium disc. Twentyfive millimeter diameter and 1mm thick Ti disc which was coated 25, 50, 100, 200microgram/ml of EMD(Emdogain(R)) used as experimental group, 25, 50, 100, 200ng/ml of rhBMP-2 as positive control group, and no coat as negative control group. A human osteosarcoma cell line Saos-2 was cultured in Ti disc and cell proliferation and Alkaline phosphatase (ALP) activity were measured at 1 and 6 days. PCR was performed at 2 and 8 hours. Semi-quantitative RT-PCR for mRNA expressions of various osteoblastic differentiation markers - type I collagen, ALP, osteopontin, and bone sialoprotein - were performed at appropriate concentrations based upon the results of MTT and ALP assay. Cultured cell-disc complexes were prepared for scanning electron microscopy (SEM) at 2 hour. Data were analyzed using Mann-Whitney and repeated- measures 1-way analysis of variance(SPSS software version 10,SPSS, Chicago, IL). After culture, there was more osteoblast in EMD100microgram/ml than in EMD50, 200microgram/ml on day 6. There was significant difference in experimental and positive control group compared control group, as times go by(1 and 6 days). Alkaline phosphatase activity was different significantly in EMD100, 200microgram/ml and BMP100, 200ng/ml on day 6. The results of reverse transcriptase-polymerase chain reaction (RT-PCR) showed that expression of mRNA for ALPase, collagen type I, osteopontin, bone sialoprotein and BMP-2 was detected at 2 hour and 8 hour in EMD200microgram/ml subgroup and BMP100ng/ml subgroup. The results of this study suggest that application of enamel matrix derivative on osteoblast attached to titanium surface facilitate the expression of bone specific protein and the differentiation and growth of osteoblast.

Pleomorphic Xanthoastrocytoma: Report of 3 Cases

Pleomorphic xanthoastrocytoma(PXA) is a rare neoplasm with favorable prognosis despite of its aggressive histological features. The authors report three cases of pleomorphic xanthoastrocytomas. The masses were in the temporal or parietal lobe of children or adolscence and presented as complex partial seizures. Total removal of mass was performed in all three cases and the seizure was abscent postoperatively. It is important to differentiate of pleomorphic xanthoastrocytoma from other malignant brain tumors and identify this type of glioma as a distinct entity.