• Journal of Periodontal and Implant Science
• /
• 제31권1호
• /
• pp.41-57
• /
• 2001

It is well known that the apposition of bone at implant surface would be influenced by the microstructure of titanium implants. The purpose of this study was to compare bone healing around the screw-shaped titanium implant with three different surface topographies in the canine mandibles by histological and biomechanical evaluation. All mandibular premolars of six mongrel dogs were extracted and implants were placed one month later. The pure titanium implants had different surface topographies: smooth and machined ($Steri-OSS^{(R)}$: Group II); sandblasted and acid-etched ($ITI^{(R)}$, SLA: Group III) surface. The fluorescent dyes were injected on the 2nd (calcein), 4th (oxytetracycline HCI) and 12th (alizarin red) weeks of healing. Dogs were sacrificed at 4 and 12 weeks after implantation. The decalcified and undecalcified specimens were prepared for histological and histo-metrical evaluation of implant-bone contact. Some specimens at 12 weeks after implantation were used for removal torque testing. Histologically, direct bone apposition to implant surface was found in all of the treated groups. More mature and dense bone was observed at the implant-bone interface at 12 weeks than that at 4 weeks after implantation. Under the fluorescent microscope, thick regular green fluorescent lines which mean early bone apposition were observed at the implant-bone interface in Group III, while yellow and red fluorescent areas were found at the implant-bone interface in Group I and II. The average implant-bone contact ratios at 4 weeks of healing were 54.3% in Group I, 57.7% in Group II and 66.2% in Group III. In Group I, implant-bone contact ratio was significantly lower than Group II and III(p<0.05). The average implant-to-bone contact ratios at 12 weeks after implantation were 64.3% in Group I, 66.7% in Group II and 71.2% in Group III. There was no significant difference among the three groups. In Group I and II, the implant-bone contact ratio at 12 weeks increased significantly in comparison to ratio at 4 weeks(p<0.05). The removal torque values at 12 weeks after implantation were 90.9 Ncm in Group I, 81.6 Ncm in Group II and 77.1 Ncm in Group III, which were significantly different(p<0.05). These results suggest that bone healing begin earlier and be better around the surface-treated implants compared to the smooth surface implants. The sandblasted and acid-etched implants showed the most favorable bone response among the three groups during the early healing stage and could reduce the waiting period prior to implant loading.

• 대한치과의사협회지
• /
• 제47권11호
• /
• pp.758-768
• /
• 2009

Purpose : Schulte introduced immediate implant cases in 1970s, since then many patients have been treated by immediate implants. The aim of this study was to evaluate the cumulative survival rate of immediate implant and to analyze various factors associated with survival of immediate implant in a 8-year period retrospectively. Materials and methods : From May, 2000 to October, 2007, 77 implants were placed in 63 patients immediately after tooth extraction at Department of Periodontology, Yonsei University Hospital. The implant survival rate was analyzed using a life-table analysis. After delivery of prosthesis, along 1 year of observation period, all implants were evaluated clinically and radiographically. Results : Among 77 implants, 59 were placed in maxilla and 18 in mandible. The most common site of the implantation was Mx anterior (65%). The overall survival rate was 94.8% over a mean follow-up period of $44.2{\pm}21$ months and the 8-year cumulative survival rate was 94.6%. Failure occurred in 4 implants, all of which were due to early failures. None of the following factors were significantly associated with the survival of immediate implants: advanced surgical technique including bone graft and guided bone regeneration, the types of implants, causes of tooth loss, and types of prosthesis. Conclusion : On the basis of 8-year life time analysis, immediate implant placement can be considered a safe and predictable treatment mordality.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제34권3호
• /
• pp.285-292
• /
• 2008

Purpose: The present study was performed to evaluate the effect of surface treatment of the cervical area of implant on bone regeneration in fresh extraction socket following implant installation. Materials and methods: The four minipigs, 18 months old and 30 kg weighted, were used. Four premolars of the left side of both the mandible and maxilla were extracted. ${\phi}$3.3 mm and 11.5 mm long US II plus implants (Osstem Implant co., Korea) with resorbable blasting media (RBM) treated surface and US II implants (Osstem Implant co., Korea) with machined surface at the top and RBM surface at lower portion were installed in the socket. Stability of the implant was measured with $Osstell^{TM}$ (Model 6 Resonance Frequency Analyser: Integration Diagnostics Ltd., Sweden). After 2 months of healing, the procedures and measurement of implant stability were repeated in the right side by same method of left side. At four months after first experiment, the animals were sacrificed after measurement of stability of all implants, and biopsies were obtained. Results: Well healed soft tissue and no mobility of the implants were observed in both groups. Histologically satisfactory osseointegration of implants was observed with RBM surface, and no foreign body reaction as well as inflammatory infiltration around implant were found. Furthermore, substantial bone formation and high degree of osseointegration were exhibited at the marginal defects around the cervical area of US II plus implants. However, healing of US II implants was characterized by the incomplete bone substitution and the presence of the connective tissue zone between the implant and newly formed bone. The distance between the implant platform (P) and the most coronal level of bone-to-implant contact (B) after 2 months of healing was $2.66{\pm}0.11$ mm at US II implants group and $1.80{\pm}0.13$mm at US II plus implant group. The P-B distance after 4 months of healing was $2.29{\pm}0.13$mm at US II implants group and $1.25{\pm}0.10$mm at US II plus implants group. The difference between both groups regarding the length of P-B distance was statistically significant(p<0.05). Concerning the resonance frequency analysis (RFA) value, the stability of US II plus implants group showed relatively higher RFA value than US II implants group. Conclusion: The current results suggest that implants with rough surface at the cervical area have an advantage in process of bone regeneration on defect around implant placed in a fresh extraction socket.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제32권6호
• /
• pp.511-520
• /
• 2010

Purpose: This study was conducted in order to compare the efficacy of osseointegration of three different calcium metaphosphate (CMP) coated implants in the rabbit's femur. Materials and Methods: Twenty four rabbits and three different type of CMP coated implants and RBM implants were used in this study. The animals were divided into 4 groups on the basis of implant surface characteristics. Two implants were installed into the condyle of femur of each rabbits. The animals were sacrificed at 2 and 4 weeks after installation. The undecalcified specimens were prepared for histological, radiological examination and histomorphometric analysis of implant-bone contact ratios (BIC) and bone area ratio (BA). Results: Two implants were failed to osseointegrate and implant success rate was 95.2%. There were not any significant inflammatory response in all groups. Fluorescent image at 4 weeks shows that remodeling is slower in RBM group than CMP group. CMP III showed more active remodeling than CMP I, II. In histomorphologic analysis, BIC ratio at 2 weeks was lower than 4 weeks. Conclusion: The results suggest that the ratios of CMP coated implants were higher than that of RBM control group but there is no significantly difference between RBM group and CMP group. In conclusion, CMP coated implant had more clinical availability than RBM implants.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제28권6호
• /
• 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.

• 구강회복응용과학지
• /
• 제19권1호
• /
• pp.17-25
• /
• 2003

Treatment with implants of single tooth missing cases is both functional and esthetic. Although the success rate of single-tooth implant treatments is increasing, sometimes it makes some problems. Problems with single-tooth implant treatments include soft tissue complications, abutment screw fracture, and most commonly, abutment screw loosening, and these involve the instability of the dental implant-superstructure interface. This study investigated and compared dental implant screw joint micromotion of various implant system with external connection or internal connection when tested under simulated clinical loading, Six groups (N=5) were assessed: (1) Branemark AurAdapt (Nobel Biocare, Goteborg, Sweden), (2) Branemark EsthetiCone (Nobel Biocare, Goteborg, Sweden), (3) Neoplant Conical (Neobiotec, Korea), (4) Neoplant UCLA (Neobiotec, Korea), (5) Neoplant 5.5mm Solid (Neobiotec, Korea), and (6) ITI SynOcta (Institute Straumann, Waldenburg, Switzerland). Six identical frameworks were fabricated. Abutment screws were tightened to 32-35 Ncm and occlusal screw were tightened to 15-20 Ncm with an electronic torque controller. A mechanical testing machine applied a compressive cyclic load of 20kg at 10Hz to a contact point on each implant crown. Strain gauge recorded the micromotion of the screw joint interface once a second. Data were selected at 1, 500, 5,000, 10,000, 20,000, 30,000, 40,000 and 50,000 cycle and 2-way ANOVA test was performed to assess the statistical significance. The results of this study were as follows; The micromotion of the implant-superstructure in the interface increased gradually through 50,000 cycles for all implant systems. In the case of the micromotion according to cycle increase, Neoplant Conical and Neoplant UCLA system exhibited significantly increasing micromotion at the implant-superstructure interface (p<0.05), but others not significant. In the case of the micromotion of the implant-superstructure interface at 50,000 cycle, the largest micromotion were recorded in the Branemark EsthetiCone, sequently followed by Neoplant Conical, Neoplant UCLA, Branemark AurAdapt, ITI SynOcta and Neplant Solid. Internal connection system showed smaller micromotion than external connection system. Specially, Neoplant Solid with internal connection system exhibited significantly smaller micromotion than other implant systems except ITI SynOcta with same internal connection system (p<0.05). In the case of external connection, Branemark EsthetiCone and Neoplant Conical system with abutment showed significantly larger micromotion than Branemark AurAdapt without abutment (p<0.05).

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제31권2호
• /
• pp.136-142
• /
• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• 구강회복응용과학지
• /
• 제17권4호
• /
• pp.283-305
• /
• 2001

The purpose of this study was to analyze the stress distribution of condylar regions and edentulous mandible with implant-supported cantilever prostheses on the certain conditions, such as amount of load, location of load, direction of load, fixation or non-fixation on the condylar regions. Three dimensional finite element analysis was used for this study. FEM model was created by using commercial software, ANSYS(Swanson, Inc., U.S.A.). Fixed model which was fixed on the condylar regions was modeled with 74323 elements and 15387 nodes and spring model which was sprung on the condylar regions was modeled with 75020 elements and 15887 nodes. Six Br${\aa}$nemark implants with 3.75 mm diameter and 13 mm length were incorporated in the models. The placement was 4.4 mm from the midline for the first implant; the other two in each quardrant were 6.5 mm apart. The stress distribution on each model through the designed mandible was evaluated under 500N vertical load, 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. The load points were at 0 mm, 10 mm, 20 mm along the cantilever prostheses from the center of the distal fixture. The results were as follows; 1. The stress distribution of condylar regions between two models showed conspicuous differences. Fixed model showed conspicuous stress concentration on the condylar regions than spring model under vertical load only. On the other hand, spring model showed conspicuous stress concentration on the condylar regions than fixed model under 250N horizontal load linguobuccally, buccal 20 degree 250N oblique load and buccal 45 degree 250N oblique load. 2. Fixed model showed stress concentration on the posterior and mesial side of working and balancing condylar necks but spring model showed stress concentration on the posterior and mesial side of working condylar neck and the posterior and lateral side of balancing condylar neck under vertical load. 3. Fixed model showed stress concentration on the posterior and lateral side of working condylar neck and the anterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior sides of working and balancing condylar necks under horizontal load linguobuccally. 4. Fixed model showed stress concentration on the posterior side of working condylar neck and the posterior and lateral side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 20 degree oblique load. 5. Fixed model showed stress concentration on the anterior and lateral side of working condylar neck and the posterior and mesial side of balancing condylar neck but spring model showed stress concentration on the anterior side of working condylar neck and the anterior and lateral side of balancing condylar neck under buccal 45 degree oblique load.. 6. The stress distribution of bone around implants between two models revealed difference slightly. In general, magnitude of Von Mises stress was the greatest at the bone around the most distal implant and the progressive decrease more and more mesially. Under vertical load, the stress values were similar between implant neck and superstructure vertically, besides the greatest on the distal side horizontally. 7. Under horizontal load linguobuccally, buccal 20 degree oblique load and buccal 45 degree oblique load, the stress values were the greatest on the implant neck vertically, and great on the labial and lingual sides horizontally. After all, it was considered that spring model was an indispensable condition for the comprehension of the stress distributions of condylar regions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제36권5호
• /
• pp.417-422
• /
• 2010

Introduction: Bone density is one of the important factors for the long term success of endosseous implants. The bone density varies from site to site and from patient to patient. A preoperative evaluation of the bone density is quite useful to oral surgeons for planning dental implantation. More accurate information on the bone density will help surgeons identify suitable implant sites, thereby increase the success rate of dental implantation. This study examined the correlation between the bone density measured preoperatively by computed tomography (CT) and the implant primary stability measured by resonance frequency analysis. Furthermore, the effects of the implant sites, gender, age and generalized systemic disorder patients on the bone density and primary implant stability were examined. Materials and Methods: One hundred and fourteen patients were selected. None of the patients had undergone a tooth extraction or bone graft history in the previous year. Preoperatively, the patients underwent CT scanning to evaluate the Hounsfield unit (HU), and resonance frequency analysis (RFA) was used to evaluate the implant primary stability at the time of implant installation. All implants were 4.0 mm diameter and 11.5 mm length US II. All patients were recorded and the HU and implant stability quotient (ISQ) value were evaluated according to the sites, gender and age. Results: The highest HU values were found in the mandibular anterior site ($827.6{\pm}151.4$), followed by the mandibular molar site ($797{\pm}135.1$), mandibular premolar site ($753.8{\pm}171.2$), maxillary anterior site ($726.3{\pm}154.4$), maxillary premolar site ($656.7{\pm}173.8$) and maxillary molar site ($621.5{\pm}164.9$). The ISQ value was the highest in the mandibular premolar site ($81.5{\pm}2.4$) followed by the mandibular molar site ($80.0{\pm}5.7$), maxillary anterior site ($77.4{\pm}4.1$), mandibular anterior site ($76.4{\pm}11.9$), maxillary premolar site ($74.2{\pm}14.3$) and maxillary molar site ($73.7{\pm}7.4$). The mean HU and ISQ value were similar in females and males. (HU: P=0.331, ISQ: P=0.595) No significant difference was also found in the age group respectively. However, the correlation coefficients between the variables showed a closed correlation between the HU and ISQ value. Conclusion: These results showed close correlation between the bone density (HU) and primary stability value (ISQ) at the time of implant installation (Correlation coefficients=0.497, P<0.01). These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis.

• 구강회복응용과학지
• /
• 제27권1호
• /
• pp.1-13
• /
• 2011

압축강화형 복합레진($TESCERA^{TM}$ ATL)을 지르코니아 framework에 효과적으로 전장하기 위하여, 표면처리 방법을 여러 가지로 달리한 지르코니아 표면에 압축강화형 복합레진을 전장하여 전단결합강도를 실험적으로 비교하였다. 지르코니아의 표면적 증가를 도모하기 위해 최종소결 전 지름 1.1mm round bur를 사용하여 지르코니아 표면에 pockmark (honey-comb concept)를 형성하였고, 화학적으로는 Primer (Zr-plus primer, Bisco, Inc., Shaumurg, USA)를 도포하여 결합강도 증가를 도모하였다. 지르코니아에 porcelain을 적층하여 대조군으로 삼고 각 군을 5도와 55도 사이에서 10,000회 thermocycling시켜 simulated aging 결과 또한 비교하였다. 전단결합강도를 측정하였고 주사전자현미경을 통해 파절단면을 관찰하였다. Pockmark를 형성한 실험군에 압축강화형 복합레진($TESCERA^{TM}$ ATL) 전장 시 도재 전장과 유사한 전단결합 강도를 발휘하였으며,(p>0.05) 동일 시편을 24시간 수중 보관했을 때에 비해 thermocycling 했을 때의 전단결합강도가 약간 감소하였으나 유의차는 보이지 않았다.(p>0.05) 지르코니아 표면에의 Primer의 도포가 압축강화형 복합레진 ($TESCERA^{TM}$ ATL)과의 결합강도를 증가시키지는 못하였다. 지르코니아 소결 전 표면에 pockmark를 주어 표면적을 증가시키고 요철의 효과를 주는 것은 $TESCERA^{TM}$ ATL과의 결합강도를 증가시켰으며, 이는 임상적으로 지르코니아-포세린의 결합강도에 필적하는 강하고 내구성 있는 결합강도를 가져온다고 판단되었다.