Effect of different hydroxyapatite : β-tricalcium phosphate ratios on the osteoconductivity and dimensional stability of biphasic calcium phosphate in the rabbit sinus model

치과대학/박사Objective: The present study compared the osteoconductivity and the volume stability of biphasic calcium phosphate (BCP) with a high versus a low ratio of beta tricalcium phosphate (β-TCP) relative to hydroxyapatite (HA; i.e., 70:30 vs. 30:70) in the rabbit sinus model. Material and Methods: Experiement1-short and middle term evaluation; Bilateral sinus windows were created in eight adult New Zealand white rabbits (2.5-3.5 kg); each sinus in each rabbit was assigned to one of two experimental BCP groups according to the HA:β-TCP ratio. One sinus was grafted with BCP with a high ratio of β-TCP (i.e., 70:30; TCP70) and the contralateral sinus was grafted with BCP with a low ratio of β-TCP (i.e., 30:70; TCP30). The animals were sacrificed after 2 (n=4) or 8 weeks (n=4) of healing. Biopsy specimens were harvested and evaluated histologically, histomorphometrically, and with microcomputed tomography (micro-CT). Experiement2- late term evaluation; Experimental protocol was followed expertment1. In five rabbits, sinus augmentation was performed. Calcein green was injected five days before euthanizing. The animals were euthanized 16 weeks postsurgery. Results: Experiement1; The total augmented volume (TV) in micro-CT, and the area of new bone (NA) and bone-to-material contact (%NPC) in histologic section did not differ significantly between the two groups at 2 and 8 weeks of healing. The augmented volume did not show significant decrease between 2 and 8 weeks. The residual material was significantly more resorbed in the TCP70 group than in the TCP30 group at both 2 and 8 weeks. Larger amount of multinucleated giant cell was observed in the TCP70 group at both weeks. Experiement2; Micro-CT analysis revealed that TV and new bone volume (NV) did not show statistical difference between both groups, but the resorption of materials was statistically higher in the TCP70 group than the TCP30 group. Histomorphometrically, TA, NA and the area of residual material (RA), and %NPC did not differ significantly. Trabecular thickness, number and separation were not statistically significant between both groups. Fluorescence with calcein green showed no notable difference between both groups. Conclusion: Within limitation of this study, the BCPs with HA: β-TCP = 3:7 and 7:3 were demonstrated to be comparably effective in maintaining volume stability and bone formation.ope

Oral signs of acute leukemia for early detection.

PURPOSE: Systemic disease can manifest oral signs at an early phase, which may be crucial for the diagnosis and timing of treatment. This report describes two patients who presented with gingival enlargement as an early sign of acute leukemia. METHODS: Two patients presented with oral symptoms including severe gingival enlargement. The progress of their symptoms was associated with underlying systemic disease. RESULTS: The patients were transferred to the Department of Hematology and diagnosed with acute myelomonocytic leukemia. They received appropriate treatment and survived. CONCLUSIONS: Gingival enlargement can be caused by underlying systemic diseases. Accurate diagnosis and timely referral are important for preventing a fatal situation. It must be emphasized that some oral signs and symptoms may be closely correlated with systemic diseases.ope

좁은 직경 임플란트에 관한 장기간의 후향적 연구 결과

Purpose: The aim of this study was to retrospectively investigate (investigate retrospectively may be better) the survival rate and the influencing factors of narrow implants less than 3.5 mm in diameter. Materials and Methods: Included this study were the patients who received the implantation from January 1995 to December 2011 and visited the Department of Periodontology, Dental Hospital of Yonsei University after over 12 months from the time of their implantation. The cumulative survival rate was calculated and various factors affecting the rate were investigated according to the implant system, gender, age, implant position, length, and splinting. The causes of failed implants were also analyzed. Results: The overall survival rate was 98.6% and 11 implants were removed. There was no statistically significant differences among the survival rate according to the implant system, gender, position, length and the existence of splinting. The most frequent/common reason for failure was infection, which was responsible for 8 out of 11 failed implants. Conclusion: In conclusion, the present study suggests that the use of narrow diameter implants can be a predictable treatment option.ope

Development of Scaffold for Cell Attachment and Evaluation of Tissue Regeneration Using Stem Cells Seeded Scaffold

Purpose: The purpose of this study was to review the outcomes of a series of studies on tissue regeneration conducted in multiple institutions including the Department of Periodontology, College of Dentistry, Yonsei University. Materials and Methods: Studies were performed divided into the following three subjects; 1) Development of three-dimensional nano-hydroxyapatite (n-HA) scaffold for facilitating drug release and cell adhesion. 2) Synergistic effects of bone marrow-derived mesenchymal stem cells (BMMSC) application simultaneously with platelet-rich plasma (PRP) on HA scaffolds. 3) The efficacy of silk scaffolds coated with n-HA. Also, all results were analyzed by subjects. Results: Hollow hydroxyapatite spherical granules were found to be a useful tool for the drug release and avidin-biotin binding system for cell attachment. Also, BMMSC simultaneously with PRP applied in an animal bone defect model was seen to be more synergistic than in the control group. But, the efficacy of periodontal ligament cells and dental pulp cells with silk scaffolds could not be confirmed in the initial phase of bone healing. Conclusion: The ideal combination of three elements of tissue engineering−scaffolds, cells and signaling molecules could be substantiated due to further investigations with the potentials and limitations of the suggested list of studies.ope

Biocompatibility and Resorption Pattern of Newly Developed Hyaluronic Acid Hydrogel Reinforced Three-layer Poly(Lactide-co-glycolide) Membrane: histologic observation in rabbit calvarial defect model

BACKGROUND: The aim of this study was to evaluate the biocompatibility and resorption pattern in three-layer poly (lactide-co-glycolide) (PLGA) membrane according to the concentrations of hyaluronic acid (HA) hydrogel in rabbit calvarial defect model. Four standardized circular defects with 8 mm diameter were created on the four rabbit calvarium. Three-layer PLGA membranes (5% and 10% HA gel) were used as the test groups, both collagen membrane and monolayer PLGA membrane as the control groups. RESULTS: After sacrificing the animals after 4 and 8 weeks, block sections were harvested and histological observation was performed. Pus formation was observed in a site on the three-layer PLGA membranes (with 10% HA gel) of 4 weeks group and initial inflammatory responses were observed on the three-layer PLGA membrane group. However, when compared to both the monolayer PLGA membrane group and collagen membrane group, the HA gel-reinforced three-layer PLGA membrane showed improved cell occlusion and retention period, showing the formation of the capsule-like structure. There was no definite difference between the results of the membranes fabricated with either 5% or 10% HA hydrogel. CONCLUSION: The HA reinforced three-layer PGLA membrane was retained longer than control group and showed good property in cell occlusion. Future study is under process to improve the inflammatory response of the three layer PLGA membranes, which were observed in this study.ope

Resective osseous surgery for multiple bony exostoses of the periodontal patient: A case report

Bony exostosis, one of the osseous deformities, could act as a contributing factor of periodontal disease since it makes proper tooth brushing difficult and causes traumatic ulcer. The purpose of this case report is to show improvement of periodontal health by removal of bony exostoses and creation of physiologic osseous form. A 58 year-old female patient with recurrent ulcer and pain on bony exostoses located on left maxillary palatal area and both mandibular buccal areas was treated. Exostoses were removed and physiologically positive osseous form was created following vertical grooving, radicular blending, flattening interproximal bone and gradualizing marginal bone. The patient showed no further recurring traumatic ulcer and bone exposure. Moreover, periodontal pocket was eliminated and food impaction was decreased. In conclusion, periodontal health could be achieved through removal of multiple bony exostoses and development of ideal osseous form.ope

Paracrine effect of the bone morphogeneticprotein-2 at the experimental site on healing of the adjacent control site: a study in the rabbit calvarial defect model

PURPOSE: The aim of this study was to assess the possible paracrine effect of bone morphogeneticprotein-2 (BMP-2) at the experimental site on the adjacent control site for validating a rabbit calvarial defect model as a means of verifying the effect of BMP-2. METHODS: Sixteen rabbits were divided into two groups (n=8 in each) according to whether or not BMP-2 would be used. Two circular defects (8 mm in diameter) were created side by side, 2 mm apart, in the calvarium of all of the rabbits. In each animal, one of the defects was grafted with either BMP-2-loaded carrier or carrier material alone. The control defects adjacent to these grafted defects, designated CB (the nongrafted defect adjacent BMP-2-loaded carrier-grafted defect) and CC (the nongrafted defect adjacent to carrier only-grafted defect), respectively, were the focus of this study, and were filled only with a blood clot in all of the animals. Histologic observation and histomorphometric analysis were performed at 2 and 8 weeks (n=4 animals per point in time) after surgery. RESULTS: There was no noteworthy difference in the healing pattern, and no statistically significant differences in histomorphometric parameters such as the defect closure, new bone area, or total augmented area between the CC and CB groups. CONCLUSIONS: The results of this study suggest that rabbit calvarial defects separated by a distance of 2 mm are suitable for evaluating the effects of BMP-2 and the control defect can be regarded not to be affected by BMP-2 applied defect.ope

Delayed intentional replantation of periodontally hopeless teeth: a retrospective study

PURPOSE: The purpose of this study was to retrospectively evaluate the survival of periodontally hopeless teeth that were intentionally extracted and replanted after a delay and to compare the radiographic characteristics of the survival group with those of the failure group. METHODS: The clinical and radiographic data from patients who underwent delayed intentional replantation between March 2000 and July 2010 were reviewed. Twenty-seven periodontally hopeless teeth were extracted and preserved in medium supplemented with antibiotics for 10-14 days. The teeth were then repositioned in the partially healed extraction socket and followed for 3 to 21 months. The radiographic parameters were analyzed using a paired t test and the cumulative survival rate was analyzed using Kaplan-Meier analysis. RESULTS: Seven replanted teeth failed and the overall cumulative survival rate was 66.4%. In the survival group, the amount of bone loss was reduced from 68.45% to 34.66% three months after replantation. There was radiologic and clinical evidence of ankylosis with 5 teeth. However, no root resorption was found throughout the follow-up period. In the failure group, bone formation occurred from the bottom of the socket. However, a remarkable radiolucent line along the root of a replanted tooth existed. The line lengthened and thickened as time passed. Finally, in each case of failure, the tooth was extracted due to signs of inflammation and increased mobility. CONCLUSIONS: Delayed intentional replantation has many advantages compared to immediate intentional replantation and could serve as an alternative treatment for periodontally involved hopeless teeth. However, techniques for maintaining the vitality of periodontal structures on the tooth surface should be developed for improved and predictable results.ope

Enamel Matrix Derivate for Periodontal Regeneration in the Interproximal Periodontal Defect Model

The aim of this study was to evaluate the effect of enamel matrix derivate (EMD) with combination of composite bovine-derivate xenograft on the periodontal regeneration in the interproximal periodontal defect model. The interproximal periodontal defects (IPDs) were surgically prepared between the first and second maxillary premolar, and the second and third maxillary premolar in four beagle dogs. EMD, collagenized bovine hydroxyapatite (CBHA), combination of two material, and sham surgery were allocated for each IPD. After eight weeks, the animals were sacrificed and the defects were analyzed by radiographic, histologic, and histometric methods. Regenerated woven bone was observed and cementoid was created along the adjacent root surfaces with proliferation of cementoblasts in every group. In the combination of EMD and CBHA group, Sharpey’s fiber was observed beyond the crest of new bone and along the newly formed cementum, and apical migration of junctional epithelium appeared to be blocked by new cementum. In the BC and EMD+CBHA groups, the residual bovine hydroxyapatite particles were found in the periodontal defect. No direct contact was observed between residual particles and tooth surfaces. No remarkable difference was found between the histometric results among the groups. Within the limitation of this study, EMD, CBHA, and combination of two materials showed similar periodontal regeneration in the interproximal periodontal defect model. Further investigation on combination with barrier membrane may be required for improvement of the regenerative potential.ope

Retrospective Comparison between Narrow Diameter Implants and Regular Diameter Implants Using Regenerative Procedure in the Atrophic Maxillary Anterior Area

Purpose: The present study was to retrospectively compare narrow diameter implants (NDIs) with regular diameter implants (RDIs) accompanying regenerative procedures in the atrophic maxillary anterior region. Materials and Methods: The subjects were patients with NDIs (diameter ≤3.5 mm) and RDIs (diameter ≥4.0 mm) placed in the atrophic maxillary anterior area from January 1st 2005 to December 31th 2009 at the Department of Periodontology, Dental Hospital of Yonsei University in Seoul, Korea. The cumulative survival rates were calculated. Also, the biologic and mechanical complications were examined as well. Results: The survival rate of NDIs and RDIs were 96.67% and 98.60%, respectively, which did not reach a statistical significance. The rate of membrane exposure in RDIs was 23.94%. Further, no significant mechanical complications were observed in both groups. Conclusion: Narrow diameter implants can be a good alternative for simplifying surgery and is therefore successfully used in the atrophic maxillary anterior region.ope