• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.34 no.5
• /
• pp.571-577
• /
• 2008

Introduction: Possible etiologic factors associated with bone loss around implants after implantation are surgical trauma, occlusal overload, periimplantitis, presence of micro gap and the formation of biologic distances. Tarnow et al. observed that the crestal bone loss was greater when the distance between the implants was <3mm than when the implants were ${\geq}\;3mm$ apart. The aim of this study was to evaluate the influence of different interimplant distance on marginal bone and crestal bone resorption in the beagle dogs. Materials and methods: The mandibular premolars of 5 dogs were extracted bilaterally. After 12 weeks of healing, each dog received 7 implants. On each side, implants were separated by 2mm (Group 1) and by 5mm (Group 2). After 16 weeks of healing, the dogs were sacrificed. Marginal bone loss was determined through linear measurements made between the implant-abutment junctions and the most coronal portions of the bone in contact with the implant surface. A line was drawn uniting the implant-abutment junctions of the adjacent implants, and a linear measurement was made at the midpoint in the direction of the most coronal peak of the interimplant bone crest to determine the crestal bone loss. Both of them was measured radiologically and histologically. Result and conclusion: In radiological analysis, the mean of marginal bone loss was $1.26{\pm}0.14mm$ for group 1 and $1.23{\pm}0.34mm$ for group 2, the mean of crestal bone loss was $1.10{\pm}0.14mm$ for group 1 and $1.02{\pm}0.30mm$ for group 2. The results were not statistically significant between 2 groups. In histological analysis, the mean of marginal bone loss was $1.63{\pm}0.48mm$ for group 1 and $1.62{\pm}0.50mm$ for group 2, the mean of crestal bone loss was $1.23{\pm}0.35mm$ for group 1 and $1.15{\pm}0.39mm$ for group 2. The differences were also not statistically significant. The clinical significance of this result is that the increase in the crestal bone loss results in the increase in the distance between the base of the interproximal contact of the crowns and the bone crest, and this determines if papilla will be present or absent between implants. Considering this fact, keeping up sufficient interimplant distance is important to minimize crestal bone loss.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.6
• /
• pp.579-585
• /
• 2006

Introduction: The fibular free flap is now considered as the first choice for long mandibular discontinuity defect. In spite of its good bone quality for implant installation, its diameter is too narrow to rehabilitate the masticatory function with implant installation. In this report, distraction osteogenesis was used for the augmentation of bone to install the dental implant in the mandible which was reconstructed with a vascularized fibular free flap. Patients and Methods: Three patients undertook the vertical augmentation of grafted fibular bone and dental implants were installed. On the day 8 post-surgery, the activation of the distractor was started at the rate of 1 mm twice a day. The total amount of distraction was 15 mm in two patients and 12.5 mm in one patient. Twelve implants were installed in three patients. Dental implants were simultaneously installed during removal of the distraction device in two patients. In one patient, the implant installation was delayed after device had been removed. All three patients showed the symptoms of mild to severe postoperative infection during the activation and consolidation. However, the distracted site showed undisturbed bone regeneration. Conclusion: The distraction osteogenesis showed the reliable results for the vertical augmentation of fibular bone which was used for the mandibular reconstruction. However, the great tendency of postoperative infection must be considered and clinically controlled.

• Journal of Yeungnam Medical Science
• /
• v.13 no.1
• /
• pp.22-31
• /
• 1996

It is difficult to get a satisfactory result for the correction of malunited fracture of zygoma. Triple osteotomy and reposition of malunited zygoma is accepted as the better surgical method than camouflage surgery by means of onlays, if the orbital floor is to be reconstructed. The surgical approach can be divided into bicoronal, periorbital, intraoral and old scar. In 7 patients with malunited fracture of zygoma, the authors used a limited approach through extension of periorbital incision and intraoral incision instead of wide exposure including bicoronal incision. And we performed triple osteotomy and advancement of zygoma complex. The patients were followed for 4.5 months with acceptable result, and this approach was an effective method for the relatively simple tripod type-malunited fracture of zygoma. The authors obtained following conclusions: 1. Preoperative evaluation through thorough measurement of X-rays, investigation of photographs and detail communication with the patients was an important process. 2. Through lateral extension of subciliary incision, lateral eyebrow and intraoral incision, we could obtain adequate exposure for triple osteotomy and advancement of zygoma. 3. The zygoma should be reduced and fixed in an overcorrected superior and medial direction. 4. Return of zygoma to its anatomical position was possible only when it is completely freed from the surrounding soft tissue including masseter. 5. We could not find any different results between autogenous calvareal bone graft and $Medpor^{(R)}$ insertion on the floor of orbit.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.23 no.4
• /
• pp.324-331
• /
• 2001

The present study was aimed to investigate the effects of latency period on alveolar ridge distraction using the intraoral distraction device. Nine adult mongrel dogs of either sex, weighing about 15kg, were used. They were divided into 3-day, 5-day, and 7-day groups according to the latency period. The left upper and lower premolars and first molars were extracted. Twelve weeks after the extraction, an osteotomy was performed and the distraction device was applied. After the latency period, the distraction was applied at a rate of 1.2mm for 8 days. The distraction device was left in place for 2 weeks to allow consolidation and was then removed. The animals were sacrified at 8 weeks after completion of distraction and were examined macroscopically, radiographically, and histologically. After completion of the distraction, the alveolar crest protruded prominently, showing the vertical augmentation of the alveolar bone. Soft tissues were broken down after the 6th day of distraction in 3-day latency group, and premature union occurred on the 7th day of distraction in the 7-day latency group. The average distance was $9.40{\pm}0.3mm$ in 3-day latency group, $9.35{\pm}0.1mm$ in 5-day latency group, and $8.85{\pm}0.1mm$ in 7-day latency group. In the radiograph taken at 8 weeks after distraction, there was slight bone resorption around the medial and distal edges of the alveolar bone segment, and a new bone deposition was observed in the neighboring alveolar crest area in all groups. Fibrous tissues were present in a part of the buccal cortical bone area of the distraction gap, and the woven and lamellar bones were observed in the distracted gap. There were bony bridges in the distraction gap in all animals examined. These results suggest that optimal time of latency period on alveolar ridge distraction using the intraoral distraction device is about 5 days in dogs, and about 7days in human beings.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.23 no.1
• /
• pp.87-94
• /
• 2001

The present study was performed to investigate the effect of $HTR^{(R)}$ (Hard Tissue Replacement) on osteogenesis in the mandibular bone defects. Eight adult male white rabbits weighing 2.5 to 3.0kg were used. Four bone defects (8mm in diameter and 4mm in depth) were made at the both mandibular body. In the control group, the right mesial bone defect was filled with blood clot and spontaneously healed. In the DFDB group, the right distal bone defect was filled with xenogenic demineralized freeze-dried bone. In the $HTR^{(R)}$ group, the left mesial bone defect was filled with $HTR^{(R)}$. In the $HTR^{(R)}-membrane$ group, the left distal bone defect was filled with $HTR^{(R)}$ and covered with BioMesh membrane. The rabbits were sacrified at 2,4,6 and 9 weeks after the operation and microscopic examination was performed. Results obtained were as follows: In the control and DFDB groups, inflammatory cells and the fibrous connective tissue existed and the bone growth was slower than $HTR^{(R)}$ group by 6 week, and there was intervention of the soft tissue at 9 week. In the $HTR^{(R)}$ group, bone trabeculi extended between the $HTR^{(R)}$ particles without intervention of inflammatory cells and the connective tissue at 4 and 6 weeks. In addition, extensive osseous ingrowth into the $HTR^{(R)}$ particles was observed at 9 week. Bone formation was more active in the $HTR^{(R)}$ group than the control and DFDB groups. There was not obvious difference in the bone healing rate between the $HTR^{(R)}$ and the $HTR^{(R)}-membrane$ group. These results suggest that the $HTR^{(R)}$ promotes osteogenesis in the bone defects and the $HTR^{(R)}$ group has no difference in comparison with the $HTR^{(R)}-BioMesh^{(R)}$ membrane group in bone healing.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.2
• /
• pp.111-117
• /
• 2006

An area of current research is investigating the app1ication of human mesenchymal stem cells or hMSCs as a cell-based regenerative therapy. In order to achieve effective bone regeneration, appropriate matrices functioning as cell-carriers must be identified and optimized in terms of function, efficacy and biocompatibility. Two methods of approaching optimization of matrices are to facilitate adhesion of the donor hMSCs and furthermore to facilitate recruitment of host progenitor cells to osteoblastic differentiation. Pleiotrophin is an extracellular matrix protein that was first identified in developing rat brains and believed to be associated with developing neuronal pathways. A recent publication by Imai and colleagues demonstrated that transgenic mice with upregulated pleiotrophin expression developed a greater volume of cortical as well as cancellous bone. The proposed mechanism of action of pleiotrophin is demonstrated here. Through either environmental stresses and/or intracellular regulation, there is an increase in pleiotrophin production. The pleiotrophin is released extracellularly into areas requiring bone deposition. A receptor-mediated process recruits host osteoprogenitor cells into these areas. Therefore, the aim of our study was to investigate the osteoconductive properties of pleiotrophin. We wanted to determine if pleiotrophin coating facilitates cellular adhesion and furthermore if this has any effect on hMSCs derived bone formation in an animal model. The results showed a dose dependent response of cellular adhesion in fibronectin samples, and cellular adhesion was facilitated with increasing pleiotrophin concentrations. Histologic findings taken after 5 weeks implantation in SCID mouse showed no presence of bone formation with only a dense fibrous connective tissue. Possible explanations for the results of the osteogenesis assay include inappropriate cell loading.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.2
• /
• pp.154-165
• /
• 2006

Objectives : It is difficult to place implants at a severely atrophied edentulous mandible because of vertical and horizontal alveolar defect. The autogenous and allogenic bone graft and guided bone regeneration are useful, but there are some limitations such as the resorption and infection of the grafted bone, and insufficiency of soft tissue. Distraction osteogenesis has recently evolved a challenging technique to overcome major draws of conventional augmentation procedures, we, therefore, report the four applications of implant placement after vertical alveolar distraction osteogenesis. Patients and Methods : Four patients(all female, mean age: $60{\pm}6$ years) with severe alveolar ridge deficiencies at their anterior mandible were treated with vertical alveolar distraction osteogenesis by intraoral device(Track 1.5, 15 mm model, KLS Martin, Tuttlingen, Germany) and placement of implants (Branemark MK III, TiUnite). After the latency periods of 5, 7, 8 days, distraction rhythm and rate were $0.5\;mm{\times}2\;times/day$ in the case of good bone quality, and $0.25\;mm{\times}3\;times/day$ in the case of poor bone quality. After consolidation periods of mean fifteen weeks, five implants for each patients were placed at the interforaminal area. Results : On average, a vertical gain of $11.38{\pm}1.38\;mm$ was obtained by distraction. And all distraction zone showed complete ossification by panoramic radiography. There were no postoperative complications other than numbness of lower lip in one case. Total twenty implants in four patients were placed and their outcomes were satisfactory. Conclusion : It is a useful method to place five implants after vertical distraction osteogenesis of the severely atrophied mandible for the implant-supported fixed prosthesis.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.32 no.4
• /
• pp.306-312
• /
• 2010

Purpose: The purpose of this experiment was to evaluate the clinical effect of cultured autoglogous osteoblasts as a way to treat the defect of mandible in rabbits. Materials and Methods: Twelve rabbits were used to determine the rate of osteogenesis. The osteoblasts were obtained from the iliac crest of rabbits using aspiration. They were then cultured in Dulbecco's Modified Eagles's Medium (DMEM) with beta-glycerophosophatate, L-ascorbicacid, and dexamethasone to proliferate and differentiate osteoprogenitor cells. The expression of osteogenic markers were detected by reverse transcription-polymerase chain reaction (RT-PCR) and silver nitrate staining techniques. Five, 10-mm holes were placed in each rabbit mandible to simulate defective regions with the use of a low speed trephine bur. In the experimental group, the previously cited defects were grafted with both activated osteoblastic and autogenous bone. The control group, however, was only grafted with autogenous bone. Both groups were then analyzed at 2, 4, and 8-week intervals using bone histomorphometric analysis. Results: According to histomorphologic analysis, the rates of new bone formation at the 2, 4, and 8-week intervals were 36%, 51%, and 23% for the control group, respectively; 52%, 39%, and 28%, for the experimental group, respectively. The experimental group showed higher rates of new bone formation compared to the control group at both the 2-week and 8-week interval. Conclusion: Bone marrow-derived osteoblasts seems to be a promising bone graft material.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.32 no.4
• /
• pp.313-323
• /
• 2010

Purpose: This study was conducted to evaluate the effect of beta-tricalcium phosphate (Cerasorb$^{(R)}$, Germany) and deproteinized bovine bone (Bio-Oss$^{(R)}$, Switzerland) grafted to the defect of rat calvaria artificially created and the effect of use of absorbable membrane (BioMesh$^{(R)}$, Korea) on new bone formation. Materials and Methods: Transosseous circular calvarial defects with diameters of 5 mm were prepared in the both parietal bone of 30 rats. In the control group I, no specific treatment was done on the defects. In the control group II, the defects were covered with absorbable membrane. In the experimental group I, deproteinized bovine bone was grafted without absorbable membrane; in the experimental group II, deproteinized bovine bone was grafted with absorbable membrane; in the experimental group III, beta-tricalcium phosphate was grafted without absorbable membrane; in the experimental group IV, beta-tricalcium phosphate was grafted with absorbable membrane. The animals were sacrificed after 3 weeks and 6 weeks respectively, and histologic and histomorphometric evaluations were performed. Results: Compare to the control groups, the experimental groups showed more newly formed bone. Between the experimental groups, beta-tricalcium phosphate showed more resorption than deproteinized bovine bone. Stabilization of grafted material and interception of the soft tissue invasion was observed in the specimen treated with membrane. There was no statistical difference between the experimental group I, III and experimental group II, IV classified by graft material, but statistically significant increase in the amount of newly formed bone was observed in the experimental group I, II and II, IV classified by the use of membrane (P<0.05). Conclusion: Both beta-tricalcium phosphate and deproteinized bovine bone showed similar osteoconductibility, but beta-tricalcium phosphate is thought to be closer to ideal synthetic graft material because it showed higher resorption rate in vivo. Increased new bone formation can be expected in bone graft with use of membrane.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.6
• /
• pp.498-510
• /
• 2001

Distraction osteogenesis refers to the biological process responsible for new bone formation between bone segments by gradual distraction after osteotomy. For the past several years, various inconveniences including a protracted consolidation period that requires patients to wear a distractor frame longer, as well as higher medical costs, have not been remedied by improvements in osteotomy, distraction rate and monitoring system. Furthermore, side effects such as pin tract infections and soft tissue swelling may arise due to the long treatment period. These drawbacks form the rationale of this study which purports to seek a method by which the consolidation period can be reduced. This paper examines how platelet-rich plasma(PRP), known to facilitate osteogenesis, influences bone formation when applied in distracted area. Ten mongrel dogs, which were made to wear external distractor frames after osteotomy in both sides of the mandible, were used as subjects. After a 7day period of latency, distraction was carried out at a rate of 1mm/day for 14 consecutive days. After the onset of distraction, 2ml of PRP and a mixture of calcium gluconate and thrombine were injected into the center of the distracted callus on the left side of the mandible. The left was injected with PRP while the right side was set as the control site without PRP treatment. Execution at the onset of distraction and in 2 weeks, 4 weeks and 8 weeks after the consolidation period, clinical and radiographic tests, bone mineral density examination, histological examination and histomorphometric analysis were conducted to compare both sides. The results are summarized as follows: 1. Based on the clinical examination at two weeks, more remarkable cortical bone formation was found on the buccal and lingual side of the distracted area in the PRP treatment site than in the control site. No visual difference was found between the PRP treatment site and the control site at four eight weeks. 2. Based on the radiological examination, a distinct increase in the radiopaque appearance of the PRP treatment site was revealed at two weeks, but this increase appeared to slow down at four and eight weeks. 3. Examination of bone mineral density revealed a significant difference at two weeks with the PRP treatment site yielding density two times higher than the control site. This difference lessened after four weeks, and disappeared at eight weeks. 4. The histomorphometric examination revealed that about 20% more bony trabeculae area(20%, higher) was formed in the PRP treatment site than in the control site. In conclusion, it can be said that PRPs effect on stimulating bone formation in the PRP treatment site manifest as early as two weeks. Trabeculae formation likewise increased throughout the whole period. If this result can be applied to humans, the consolidation period can be reduced by injecting PRP into the distracted area.