• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.348-357
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• 2000

The purpose of this study is to examine the effect of partial osseointegration situation on bone loading patterns around two different free-standing screw shaped implants (Nobel Biocare, Gothenburg, Sweden and Degussa-Huls, Hanau, German). Two dimensional axisymmetric Finite element models of two implants(10mm length and 4mm diameter) were created according to different bone quantity, quality and osseointegration ratio in maxilla and mandible bone. At the same time uni-cortical and hi-cortical fixation were analyzed. Generally, full bond case showed less stress than partial bond case in overall area and mandibular model showed less amount of stress than that of maxilla model. Maximum stress of the Branemark implant is higher than that of ANKYLOS regardless of bonding ratio at crestal and apex region. However, more stress concentration was noted in ANKYLOS implant at screw body area especially in mandible. The effect of bicortical fixation on crestal bone stress reduction is dramatical in mandible however, there was no significant effect in maxillary case. The effect of partial bond on stress distribution was more significant at screw body and apex region than in crestal region. Partial bond cases demonstrated greater stress accumulation in trabecular bone than cortical bone. It is concluded that the more accurate model of implant and bone which affects stress and strain distribution is needed to mimic in vivo behavior of implants.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.806-815
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• 1998

Regular radiographic examination has been considered as an essential diagnostic method for the osseointegrated dental implantation. This study investigated the marginal bone loss through the measurement on the periapical radiograph around 46 endosseous dental implants. Marginal bone loss have been observed for 5 years after delivery of prostheses. The results were as follows : 1. According to the experimental periods, average marginal bone loss in total implant was 1.821mm in the first year, 1.833mm in the second, 1.892mm at third, 1.910mm at forth and 1.957mm at fifth after delivery of prostheses(P<0.05). 2. The average bone loss was 1.832mm in the maxillae and 1.819mm in the mandible in three years but there was no significant difference between the upper and lower jaw(P>0.05). 3. The average bone loss was 1.824mm in males and 1.818mm in females in five years but there was no significant difference according to the sex(P>0.05). These results indicate that the most of the alveolar bone loss occur within the first year after delivery of dental prostheses resulting in the exposure of polished neck positions, and the bone level stabilizes at first thread portion of the implant fixtures.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.4
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• pp.661-678
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• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of endosseous implants. This investigation evaluated the stress patterns in rectangular photoelastic models produced by four different types of dental implants such as $Br\ddot{a}nemark$, screw type of Steri-Oss, blade type of Steri-Oss, IMZ with IMC and resin tooth using the techniques of quasi-three dimensional photoelasticity. All prostheses were casted in the same nonprecious alloy and were cemented or screwed on their respective implants and abutments. 20 kg of vertical load was applied on the central fossa of casted crown and 16 kg of inclined had was applied on the top third of distal surface of casted crown respectively. The results were as follows : 1. Under the vertical load, screw implants of Steri-Oss and $Br\ddot{a}nemark$ showed increasing stress condition between and around the screw threads along the implant lateral surface and cylindrical implant of IMZ showed the less stress condition along the lateral surface with concentration of stress mostly near the root apex. 2. Under the vertical load, the stress of Steri-Oss blade was distributed uniformly at the alveolar bone under the broad blade. 3. Under the inclined load, the stress concentration of Steri-Oss screw and $Br\ddot{a}nemark$ was developed highly around the mesiocervical bone area on the contralateral side to force application. The stress of $Br\ddot{a}nemark$ with flexible gold glod was more concentrated in the cervical bone area than that of Steri-Oss with stiff screw. 4. Under the inclined load, the stress of Steri-Oss blade broadly was distributed around the mesioceivical bone area and the lower and mesial bone area of the blade. 5. Under the Inclined load, IMZ implant showed the gap between c개wn and fixture due ta deformation of the IMC and IMZ was lower in stress concentration developed around the mesiocervical bone area than $Br\ddot{a}nemark$ and Steri-Oss screw. 6. Under the inclined load, the stress magnitude induced in the mesiocervical bone area of implants was in order of $Br\ddot{a}nemark$, Steri-Oss strew, IMZ and Stsri-Oss blade. 7. Tilting forces as compared to axial forces exerted greater magnitude of stress in the cervical bone area of the implant. 8. In respect of stress distribution, Steri-Oss blade was superior than any other implants and in respect of the stability by horizontal lone, IMB and $Br\ddot{a}nemark$ was inferior than any other implants.

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.177-193
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• 2004

Several experimental studies showed that the application of small amounts of electric current to bone stimulated osteogenesis at the site of the cathode and suggested that electrical currents promote osseointegration around dental implants. The purpose of this study was to determine the effect of direct microcurrent to endosseous titanium implants placed in bone defects. The right and left 2nd, 3rd and 4th mandibular premolars in ten mongrel dogs (15Kg of weight) were extracted. One monthe later, Ti-machined screw type implants(3.8 mm diameter x 8.5 mm length, $AVANA^{(R)}$, Ostem) were placed in surgically created circumferential defect area(width 5mm, depth 4mm). The implants were divided into three groups according to the treatment modalities: Control group- implants without electrical stimulation; Experimental group I- implants with allogenic demineralized freeze dried bone grafting; and Experimental group II-implants allogenic demineralized freeze dried bone grafting and electric stimulation. The animals were sacrificed in the 4th and 8th week after implant placement and un-decalcified specimens were prepared for histological and histometrical evaluation of bone-implant contact ratio (BIC) and bone formation area ratio (BFA) in defect area. Some specimens at 8 weeks after implantation were used for removal torque testing. Histologically, there was connective tissue infiltration in the coronal part of defect area in control and the experimental group I, whereas direct bone contact was found in the experimental group II without connective tissue invasion. Average BIC ratios at 4 weeks of healing were 60.1% in the experimental group II, 47.4% in the experimental group I and 42.7% in the control. Average BIC ratios at 8 weeks after implantation were 67.6% in the experimental group II, 55.9% in the experimental group I and 54.6% in the control. The average BFA ratio was 84.0% in the experimental group II, 71.8% in the experimental group I and 58.8% in the control at 4 weeks, and the BFA ratios were 89.6% in the experimental group II, 81.4% in the experimental group I and 70.5% in the control at 8 weeks after implantation. The experimental group II showed also significantly greater BIC and BFA ratios compared to the control and the experimental group I (p<0.05). The removal torque values at 8 weeks after implantation were 56 Ncm in the experimental group II, 49 Ncm in the experimental group I and 43 Ncm in the control. There was a statistically significant difference among 3 groups (p<0.05). These results suggest that electrical stimulation improve and accelerate bone healing around endosseous titanium implants in bone defect.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.4
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• pp.240-247
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• 2009

Purpose: The purpose of this study was to evaluate marginal bone loss to the bone crest functionally loaded for up to eighteen months and also with regard to other variables of interest. Material and Methods: 135 endosseous implants(GS II, Osstem, South Korea) were placed in 35 patients. The design of GS II implant is straight with the microthread. Radiographic examinations were conducted at baseline (implant loading) and 3, 6, 9, 12 and 18 months after loading. Marginal bone level measurement was made from the reference point to the lowest observed point of contact of the marginal bone with the fixture. The reference point of the fixture was the border between the blasted surface and machined surface of the fixture. Results: Implants were on function for a mean 12.7 months(range, 3?18 months). For the 56 maxillary and 79 mandibular implants, mean marginal bone loss was 0.68 mm and 0.70 mm. Implants placed maxillary posterior area displayed more crestal bone loss than the other position. The difference between mesial and distal bone levels was statistically significant (p<0.05) with respective means of 0.51 mm and 0.62 mm. Also, The difference between bone graft group and no-bone graft group was statistically significant(p<0.05) with respective means of 0.38 mm and 0.66 mm. But no statistically significant influence of sex, type of surgery(one or two stage surgery), the implant length was observed(p>0.05). Conclusion: This study indicates the amount of marginal bone loss around implant has maintained a relative stable during follow-up periods.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.121-127
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• 2020

Prosthodontic decision and management should be considered the patient's aesthetic need for anterior teeth in maxillary edentulism. This case report describes 10-year clinical outcome of a maxillary edentulous patient was rehabilitated by means of an implant-supported fixed dental prosthesis (ISFDP) for the anterior region and a distal-extension removable partial denture (RPD) for the posterior region. The ISFDP was designed to splint 4 endosseous implants as one unit and engaged by the RPD. The edentulous mandible was restored by means of an implant-supported overdenture. Over the course, no major adverse event occurred other than wear, discoloration, and breakage of resin veneers and artificial teeth.

• Journal of Periodontal and Implant Science
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• v.36 no.1
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• pp.211-221
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• 2006

The aim of present study was to evaluate the influence of periodontal status of adjacent tooth and loading time to the prevalence of red complex of implant sulcus. In 97 patients, partially edentulous subjects with endosseous root-form implants were selected. All subjects were medically healthy and had not taken systemic antibiotics and professional plaque control 3 months before sampling. The number was as follows: clinically healthy implants:161, clinically unhealthy implants:22, clinically healthy adjacent teeth:73, clinically unhealthy adjacent teeth:38. All teeth and implants of each patient were examined probing depth(PD), modified sulcus bleeding index(mSBI), and modified plaque index(mPI), and samples of subgingival plaque were obtained at each site with sterile curet or fine paper points, then the plaque transferred to PBS. Obtained samples were examined for the presence of P. gingivalis, T. forsythensis, and T. denticola by the polymerase chain reaction (PCR). The relationship among clinical parameters and the colonizations by the 3 bacterial species from adjacent teeth and implants region were analyzed by student t-test (p<0.05). The results of this study were as follows: 1. mPI and mSBI of implant increased with increasing of same indices of adjacent tooth(p=0.03,0.001), but not in the PD . 2. The mPI, mBI, PD of implants was higher when red complex exist. 3. The prevalence of red complex was higher when the periodontal condition is unhealthy. 4. The prevalence of red complex of implants has no significant relation to the probing depth of adjacent tooth. 5. Prevalence of P. gingivalis, T. forsythensis of implants increased with loading time. (p=0.02,0.018) These results shows the importance of oral hygiene and supportive periodontal therapy.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.635-648
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• 2005

The procedure that enhances osteogenesis and shortens the healing period is required for successful implant therapy. It has been introduced that osteogenesis is enhanced by the generation of electric field. Many researchers have demonstrated that application of electric and electromagnetic field promote bone formation. It also has been shown that electrical stimulation enhances peri-implant bone formation. Recently, several investigators have reported that noninvasive electrical stimulation using negatively charged electret such as polytetrafluoroethylene(PTFE) promotes osteogenesis. Therefore, we were interested in the effect of noninvasive electrical stimulation using negatively charged electret on the periimplant bone healing. After titanium implant were installed in the proximal tibial metaphysis of New Zealand white rabbit, negatively charged PTFE membrane fabricated by corana dischage was inserted into the inner hole of the experimental implant and noncharged membrane was applied into control implant. After 4 weeks of healing, histomorphometric analysis was performed to evaluate peri-implant bone response. The histomorphometric evaluations demonstrated experimental implant tended to have higher values in the total bone-to-implant contact ratio(experimental ; $49.9{\pm}13.52%$ vs control ; $37.5{\pm}19.44%$) , the marrow bone contact ratio(experimental ; $34.94{\pm}13.32%$ vs control ; $24.15{\pm}13.69%$), amount of newly formed bone in the endosteal region(experimental ; $1.00{\pm}0.30mm$ vs control ; $0.61{\pm}0.24mm$) and bone area in the medullary canal(experimental ; $13.55{\pm}4.98%$ vs control ; $9.03{\pm}3.05%$). The mean values of the amount of newly formed bone(endosteal region) and bone area(medullary canal) of the experimental implant demonstrated a statistically significant difference as compared to the control implant(p<0.05). In conclusion, noninvasive electrical stimulation using negatively charged electret effectively promoted peri-implant new bone formation in this study. This method is expected to be used as one of the useful electrical stimulation for enhancing bone healing response in the implant therapy

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.3
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• pp.266-275
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• 2008

Dental endosseous implants require sufficient alveolar bone volume and quality for complete bone coverage and initial stability. But, atrophy or resorption of alveolar bone height and width according to patient's age and period of tooth loss can prevent ideal implant placement. Bone graft procedure has been proposed before or simultaneously with the placement of dental implants in patients with insufficient alveolar bone volume. While allografts, xenografts, and alloplastic bone grafts have been proposed and studied for alveolar ridge augmentation, the use of autogenous bone grafts represents the 'gold standard' for bone augmentation procedures. Conventional bone grafts are usually harvested from distant sites such as the ilium or ribs. Recently there is a growing use of intraoral bone grafts from intraoral donor sites such as mandibular symphysis, mandibular ramus and maxillary tuberosity. We recommend that the mandibular ramus is a safe autogenous bone graft donor site for bone harvesting with low morbidity. We report various effective autogenous bone graft procedures from mandibular ramus for the implant placement on various atrophic alveolar ridges.

• Journal of Yeungnam Medical Science
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• v.20 no.2
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• pp.169-176
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• 2003

Background: Although dental implantation has become widespread and acceptable treatment for dental prosthodontics, maxillary posterior jaw region is often complicated by the pneumatization of the maxillary sinus and physiological resorption of the alveolar bone. When this occurs, the residual bone between the floor of the sinus and the crestal ridge is inadequate for the placement of implants. The sinus elevation procedure provides a way to increase the amount of available bone and to allow the placement of longer implants. Materials & methods: We studied 11 patients requiring the implant placements and the maxillary sinus elevation simultaneously from 1996 to 2003 in our clinic. Nine patients were males and two patients were females, aged from 39 to 72(mean=51.6). Four patients had medical compromised states; angina pectoris, diabetes, hypertension, hepatitis. Patients didn't show any pathologic findings clinically or radiographically. We studied the success and survival rate of implants, factors increasing the osseointegrating capacity of implants. Results: The success rate of osseointegration of implants was 93%. At least 6 months after loading on implants, the survival rate of implants was 78.5%. Autogenous bone graft and adequate residual bone height(>6mm) increased survival rate of implants. Conclusion: Successful implant placement with maxillary sinus elevation mainly depends on sufficient residual bone height, healthy maxillary sinus, autogenous bone graft.