• Journal of Periodontal and Implant Science
• /
• v.38 no.3
• /
• pp.429-436
• /
• 2008

Purpose: The goal of periodontal regenerative therapy is to replace bone, cementum, and periodontal ligament on a previously diseased root surface, which has suffered the loss of these supporting structures. To accomplish the regeneration, a number of surgical procedures have been advocated throughout the years. There seems to be a potential for some spontaneous periodontal tissue regeneration in the bottom of periodontal defect following open flap debridement alone. The aim of this study was to analyse the radiographic bone changes over 2-year after flap operation. Material and Methods: Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients had clinical and radiographic evidence of infrabony defect(s). forty two sites of 33 patients aged 26 to 65 (mean age 45.5) were treated by flap operation with or without osseous surgery. Baseline and over 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, gender, defect depth, defect angle) using the paired t-test were examined. Result: We observed 0.74 mm of bone fill, 0.66 mm of crestal resorption, 1.40 mm of defect resolution, and 27% of percentage of defect resolution. Mandible, women, deeper initial defect depth, narrower initial defect angle showed greater bone fill, defect resolution, and % of defect resolution. Conclusion: The results of this study suggest that the use of flap operation did enhance the outcome in terms of radiographically detectable bone fill. Both treatment resulted in some loss of crestal bone height.

• Journal of Periodontal and Implant Science
• /
• v.39 no.1
• /
• pp.71-76
• /
• 2009

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 3mm 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 $2.45{\pm}2.35\;mm$ in experimental group and $4.49{\pm}3.10\;mm$ 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.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.4
• /
• pp.630-635
• /
• 2004

The etiology of mesiodens is unknown but the most widely accepted theory is the hyperactivity of the dental lamina. Complications of mesiodens are delayed or prevented eruption of maxillary central incisors, displacement or rotation of permanent teeth, crowding of affected region, abnormal diastema or permanent space closure, dilaceration or abnormal root development of permanent teeth, primordial or follicular cyst formation, root resorption of adjacent teeth, eruption into nasal cavity. If mesiodens rotate the maxillary central incisors, space deficiency is not common and relapse is very common. So overcorrection is needed. To prevent the rotational relapse, early treatment, overcorrection, long retention period, properly formed proximal surface, use of coupled force, and surgical techniques have been suggested. The authors present two cases, whose chief complain were severely rotated maxillary incisors by mesiodens, treated by orthodontic and surgical technique and showed good results.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.45 no.3
• /
• pp.123-128
• /
• 2019

Demineralized dentin matrix (DDM) has been used as a recombinant human bone morphogenetic protein-2 (rhBMP-2) carrier in many clinical trials. To optimize the clinical safety and efficacy of rhBMP-2 with DDM, efforts have been made to improve the delivery of rhBMP-2 by 1) lowering the administered dose, 2) localizing the protein, and 3) prolonging its retention time at the action site as well as the bone forming capacity of the carrier itself. The release profile of rhBMP-2 that is associated with endogenous BMP in dentin has been postulated according to the type of incorporation, which is attributed to the loosened interfibrillar space and nanoporous dentinal tubule pores. Physically adsorbed and modified, physically entrapped rhBMP-2 is sequentially released from the DDM surface during the early stage of implantation. As DDM degradation progresses, the loosened interfibrillar space and enlarged dentinal tubules release the entrapped rhBMP-2. Finally, the endogenous BMP in dentin is released with osteoclastic dentin resorption. According to the postulated release profile, DDM can therefore be used in a controlled manner as a sequential delivery scaffold for rhBMP-2, thus sustaining the rhBMP-2 concentration for a prolonged period due to localization. In addition, we attempted to determine how to lower the rhBMP-2 concentration to 0.2 mg/mL, which is lower than the approved 1.5 mg/mL.

• Journal of Periodontal and Implant Science
• /
• v.54 no.3
• /
• pp.177-188
• /
• 2024

Purpose: Placing dental implants in areas with low bone density or in conditions where bone healing is suppressed is challenging for clinicians. An experiment using a rodent model was performed with the aim of determining the efficacy of host modulation by increasing the systemic level of cholesterol sulfate (CS) using Irosustat in the context of the bone healing process around dental implants. Methods: In 16 ovariectomised female Sprague-Dawley rats, 2 implant fixtures were placed in the tibial bones (1 fixture on each side). At 1 week after surgery, the high-CS group (n=8) received Irosustat-mixed feed, while the control group (n=8) was fed conventionally. Block specimens were obtained at 5 weeks post-surgery for histologic analysis and the data were evaluated statistically (P<0.05). Results: Unlike the high-CS group, half of the specimens in the control group demonstrated severe bone resorption along with a periosteal reaction in the cortex. The mean percentages of bone-to-implant contact (21.5%) and bone density (28.1%) near the implant surface were significantly higher in the high-CS group than in the control group (P<0.05), as was the number of Haversian canals (by 5.3). Conclusions: Host modulation by increasing the CS level may enhance the osseointegration of dental implants placed under conditions of impaired bone healing.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.4
• /
• pp.424-434
• /
• 2009

Statement of problem: Problems such as loosening and fractures of retained screws and fracture of implant fixture have been frequently reported in implant prosthesis. Purpose: Implant has weak mechanical properties against lateral loading compared to vertical occlusal loading, and therefore, stress analysis of implant fixture depending on its material and geometric features is needed. Material and methods: Total 28 of external hexed implants were divided into 7 of 4 groups; Group A (3i, FULL $OSSEOTITE^{(R)}$Implant), Group B (Nobelbiocare, $Br{\aa}nemark$ $System^{(R)}$Mk III Groovy RP), Group C (Neobiotec, $SinusQuick^{TM}$ EB), Group D (Osstem, US-II). The type III gold alloy prostheses were fabricated using adequate UCLA gold abutments. Fixture, abutment screw, and abutment were connected and cross-sectioned vertically. Hardness test was conducted using MXT-$\alpha$. For fatigue fracture test, with MTS 810, the specimens were loaded to the extent of 60-600 N until fracture occurred. The fracture pattern of abutment screw and fixture was observed under scanning electron microscope. A comparative study of stress distribution and fracture area of abutment screw and fixture was carried out through finite element analysis Results: 1. In Vicker's hardness test of abutment screw, the highest value was measured in group A and lowest value was measured in group D. 2. In all implant groups, implant fixture fractures occurred mainly at the 3-4th fixture thread valley where tensile stress was concentrated. When the fatigue life was compared, significant difference was found between the group A, B, C and D (P<.05). 3. The fracture patterns of group B and group D showed complex failure type, a fracture behavior including transverse and longitudinal failure patterns in both fixture and abutment screw. In Group A and C, however, the transverse failure of fixture was only observed. 4. The finite element analysis infers that a fatigue crack started at the fixture surface. Conclusion: The maximum tensile stress was found in the implant fixture at the level of cortical bone. The fatigue fracture occurred when the dead space of implant fixture coincides with jig surface where the maximum tensile stress was generated. To increase implant durability, prevention of surrounding bone resorption is important. However, if the bone resorption progresses to the level of dead space, the frequency of implant fracture would increase. Thus, proper management is needed.

• Journal of Korean Neurosurgical Society
• /
• v.57 no.4
• /
• pp.242-249
• /
• 2015

Objective : The timing of cranioplasty and method of bone flap storage are known risk factors of non-union and resorption of bone flaps. In this animal experimental study, we evaluated the efficacy of cranioplasty using frozen autologous bone flap, and examined whether the timing of cranioplasty after craniectomy affects bone fusion and new bone formation. Methods : Total 8 rabbits (male, older than 16 weeks) were divided into two groups of early cranioplasty group (EG, 4 rabbits) and delayed cranioplasty group (DG, 4 rabbits). The rabbits of each group were performed cranioplasty via frozen autologous bone flaps 4 weeks (EG) and 8 weeks (DG) after craniectomy. In order to obtain control data, the cranioplasty immediate after craniectomy were made on the contralateral cranial bone of the rabbits (control group, CG). The bone fusion and new bone formation were evaluated by micro-CT scan and histological examination 8 weeks after cranioplasty on both groups. Results : In the micro-CT scans, the mean values of the volume and the surface of new bone were $50.13{\pm}7.18mm^3$ and $706.23{\pm}77.26mm^2$ in EG, $53.78{\pm}10.86mm^3$ and $726.60{\pm}170.99mm^2$ in DG, and $31.51{\pm}12.84mm^3$ and $436.65{\pm}132.24mm^2$ in CG. In the statistical results, significant differences were shown between EG and CG and between DG and CG (volume : p=0.028 and surface : p=0.008). The histological results confirmed new bone formation in all rabbits. Conclusion : We observed new bone formation on all the frozen autologous bone flaps that was stored within 8 weeks. The timing of cranioplasty may showed no difference of degree of new bone formation. Not only the healing period after cranioplasty but the time interval from craniectomy to cranioplasty could affect the new bone formation.

• The korean journal of orthodontics
• /
• v.18 no.2
• /
• pp.311-327
• /
• 1988

Vascular changes in the periodontal ligament of the rat incisors following application of experimental orthodontic forces were examined by the India ink perfusion method. 57 rats were used for this experiment. The rats were divided into experimental group (54 rats) and control group (3 rats). 54 experimental rats were divided into group I (27 rats) and group II (27 rats). The right and left upper incisors of group. I and group II rats were separated distally with forces of 20gm, 70gm respectively. The vascular changes of periodontal ligament were observed histologically by means of light microscope after 1, 2 and 3 days of tooth movement and 1,3,5,8,14, and 21 days after removal of orthodontic force. The results were as follows; 1. After one day of tooth movement, occlusion of blood vessels, hyalinization of periodontal ligament and resorption of alveolar bone adjacent to the alveolar crest on pressure side were observed. Above the tissue changes on the pressure side of group II were more severe than those of group I. Especially, septal bone of group II was separated after 2 days of tooth movement. 2. In tension zones, periodontal space was widened and periodontal fibers were orientated in the direction of puil. The blood vessels of periodontal ligament were distended. New bone deposition was seen along the inner surface of the alveolus after 2 days of tooth movement. 3. After 3 days of tooth movement, deposition of new bone was seen along the periosteal surface of alveolar bone on pressure side, progressing with increasing after removal of orthodontic force. Remodelling of the new bone was occurred 5 days after removal of orthodontic force. 4. 3 days after removal of orthodontic force, invasion of blood vessels into the marginal periodontal ligament on pressure side was observed clearly and the vessels below the epithelial attachment were increased. 5. After removal of orthodontic force, hyalinized structures disappeared concomittantly with an invasion of blood vessels from the neighboring periodontal ligament. 14 days after removal of orthodontic force, the vessels in the periodontal ligament of group I were finished the vascular rearrangement. 21 days after removal of orthodontic force, the vessels in the periodontal ligament of group II were finished the vascular rearrangement.

• Restorative Dentistry and Endodontics
• /
• v.22 no.1
• /
• pp.111-131
• /
• 1997

Eighty two of extracted bovine mandibular incisors were sectioned transversely through the cementoenamel junction(CEJ) and instrumented to a size minimum-# 110 file at the working length by 5.25 % NaOCl irrigation. The roots in group 1 were received a final irrigation with 10ml of 17% EDTA followed by 10ml of 5.25% NaOCl, group 2, 10ml of 40% citric acid followed by 10ml of 5.25% NaOCl, group 3, 20ml of 5.25% NaOCl, and control group, 20ml distilled water. Canal walls of four roots in each group and control group were examined by SEM(x3000). Calcium hydroxide was placed into all experimental roots except control group. Each root was placed in nalgen bottle containing unbuffered distilled water. The pH level of the medium surrounding tooth was recorded at 0, one hour, and daily for 1week, then 14days, 21days, and 28days using pH electrode. At 1, 3, 7, 14, 21days, and 28days, four roots from each group were split longitudinally and the ratio change was recorded using spectroiluorometer. The results were followings : 1. The smear layer was totally removed from canal walls in group 1 and 2, but was observed in group 3 and control group. 2. The hydroxyl ion diffused more rapidly through radicular dentin when smear layer was removed from canal walls. 3. The hydroxyl ion derived from calcium hydroxide began to diffuse from the root canal to the exterior surface of the root at 1day, and continued to 1-2weeks. 4. The pH level of dentin near the CEJ was not different in all experimental group regardless of presence of smear layer. It is clinically advisable to place calcium hydroxide into root canal for 1-2weeks for the purpose of expectation of diffusion of hydroxyl ion. But, after the placement of calcium hydroxide into root canal, the consequent pH level of external root surface will be futher studied with respect to it's effect on the root and periodontium.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.3
• /
• pp.325-341
• /
• 2003

Statement of problem: In cases where bony defects were present, guided bone regenerations have been performed to aid the placement of implants. Nowadays, the accepted concept is to isolate bone from soft tissue by using barrier membranes to allow room for generation of new bone. Nonresorbable membranes have been used extensively since the 1980's. However, this material has exhibited major shortcomings. To overcome these faults, efforts were made to develop resorbable membranes. Guided bone regenerations utilizing resorbable membranes were tried by a number of clinicians. $Bio-Gide^{(R)}$ is such a bioresorbable collagen that is easy to use and has shown fine clinical results. Purpose: The aim of this study was to evaluate the histological results of guided bone regenerations performed using resorbable collagen membrane($Bio-Gide^{(R)}$) with autogenous bone, bovine drived xenograft and combination of the two. Surface morphology and chemical composition was analyzed to understand the physical and chemical characteristics of bioresorbable collagen membrane and their effects on guided bone regeneration. Material and methods: Bioresorbable collagen membrane ($Bio-Gide^{(R)}$), Xenograft Bone(Bio-Oss), Two healthy, adult mongrel dogs were used. Results : 1. Bioresorbable collagen membrane is pure collagen containing large amounts of Glysine, Alanine, Proline and Hydroxyproline. 2. Bioresorbable collagen membrane is a membrane with collagen fibers arranged more loosely and porously compared to the inner surface of canine mucosa: This allows for easier attachment by bone-forming cells. Blood can seep into these spaces between fibers and form clots that help stabilize the membrane. The result is improved healing. 3. Bioresorbable collagen membrane has a bilayered structure: The side to come in contact with soft tissue is smooth and compact. This prevents soft tissue penetration into bony defects. As the side in contact with bone is rough and porous, it serves as a stabilizing structure for bone regeneration by allowing attachment of bone-forming cells. 4. Regardless of whether a membrane had been used or not, the group with autogenous bone and $Bio-Oss^{(R)}$ filling showed the greatest amount of bone fill inside a hole, followed by the group with autogenous bone filling, the group with blood and the group with $Bio-Oss^{(R)}$ Filling in order. 5. When a membrane was inserted, regardless of the type of bone substitute used, a lesser amount of resorption occurred compared to when a membrane was not inserted. 6. The border between bone substitute and surrounding bone was the most indistinct with the group with autogenous bone filling, followed by the group with autogenous bone and $Bio-Oss^{(R)}$ filling, the group with blood, and the group with $Bio-Oss^{(R)}$ filling. 7. Three months after surgery, $Bio-Gide^{(R)}$ and $Bio-Oss^{(R)}$ were distinguishable. Conclusion: The best results were obtained with the group with autogenous bone and $Bio-Oss^{(R)}$ filling used in conjunction with a membrane.