• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.4
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• pp.235-243
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• 2019

Osseointegration has been reported to be a dynamic process in which the alveolar bone comes in direct contact with the implant. Various methods were tried to evaluate degree of osseointegration and the measurement of bone-implant contact (BIC) have been commonly used among them. To properly assess the BIC, only histologic analysis is available. However, few studies evaluated BIC of successfully osseointegrated implants in humans. Thus, this is a unique opportunity when implants should be explanted due to inappropriate positioning of implant, presence of pain or sensory disturbance, or broken screw or fixture. This report presents a case of the implant underwent 3-year functional load and a histologic analysis after the fixture fracture. The histomorphometric analysis revealed 53.1% of BIC measured along the whole implant and 70.9% measured only in subcrestal area, respectively. In the present study, although the implant was fractured, a high degree of BIC was observed.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.214-221
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• 2011

Purpose: To date most of finite element analysis assumed the presence of 100% contact between bone and implant, which is inconsistent with clinical reality. In human retrieval study bone-implant contact (BIC) ratio ranged from 20 to 80%. The objective of this study was to explore the influence of bone-implant contact pattern on bone of the interface using nonlinear 3-dimensional finite element analysis. Materials and methods: A computer tomography-based finite element models with two types of implant (Mark III Br${\aa}$nemark$^{(R)}$, Inplant$^{(R)}$) which placed in the maxillary 2nd premolar area were constructed. Two different degrees of bone-implant contact ratio (40, 70%) each implant design were simulated. 5 finite element models were constructed each bone-implant contact ratio and implant design, and sum of models was 40. The position of bone-implant contact was determined according to random shuffle method. Elements of bone-implant contact in group W (wholly randomized osseointegration) was randomly selected in terms of total implant length including cortical and cancellous bone, while ones in group S (segmentally randomized osseointegration) was randomly selected each 0.75 mm vertically and horizontally. Results: Maximum von Mises strain between group W and group S was not significantly different regardless of bone-implant contact ratio and implant design (P=.939). Peak von Mises strain of 40% BIC was significantly lower than one of 70% BIC (P=.007). There was no significant difference between Mark III Br${\aa}$nemark$^{(R)}$ and Inplant$^{(R)}$ in 40% BIC, while average of peak von Mises strain for Inplant$^{(R)}$ was significantly lower ($4886{\pm}1034\;{\mu}m/m$) compared with MK III Br${\aa}$nemark$^{(R)}$ ($7134{\pm}1232\;{\mu}m/m$) in BIC 70% (P<.0001). Conclusion: Assuming bone-implant contact in finite element method, whether the contact elements in bone were wholly randomly or segmentally randomly selected using random shuffle method, both methods could be effective to be no significant difference regardless of sample size.

• Journal of Periodontal and Implant Science
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• v.36 no.4
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• pp.913-923
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• 2006

목적 : 최근 발치 후 즉시 임플란트 식립은 널리 사용되는 수술 방식이다. 이 연구의 목적은 임플란트 주위 골결손시 Ca-P으로 표면 처리된 이종골을 사용하여 골재생을 평가하기 위함이다. 재료와 방법 : 두 마리의 개 모델에서 하악 소구치와 제일 대구치를 발치하였다. 발치 6주 후 trephine bur를 이용하여 7.5 mm 지름과 5 mm 깊이를 가진 결손부를 형성하였다. 이 후 이 결손부의 중앙에 3.5 mm 지름과 15mm 길이의 fixture(GS II)를 식립하였다. 결과적으로 임플란트와 주변을 둘러싸고 있는 골 사이에는 2.0 mm정도의 gap이 만들어진다. 준비된 결손부 내로 자기골 또는 $Biocera^{(R)}$를 채웠다. 각각 4주, 8주 후 조직 절편을 제작하였다. 조직학적 평가를 위해 Block biopsy를 시행하였다. 결과 : 두 집단 모두 임상적으로 골이 완전히 채워졌다. 자가골이 이식된 부위(control)의 평균 골-임플란트 접촉(BIC)은 각각 4주째 $28.2{\pm}19%$였고, 8주째 $44.9{\pm}9%$였다. $Biocera^{(R)}$가 이식된 부위(test)의 평균 BIC는 각각 4주째 $34.6{\pm}27%$였고, 8주째 $27.6{\pm}23%$였다. 자가골이 이식된 부위(control)의 평균 골밀도는 각각 4주째 $32.7{\pm}25%$, 8주째 $37.4{\pm}17%$였다. 골-임플란트 접촉(BIC)과 골밀도의 평균 비율(%)은 비슷하였다. 조직학적으로 자가골과 이종골 이식 부위 모두 주변골과 잘 조화를 이루었고 유사한 치유 양상이 관찰되었다. 자가골과 이종골 이식 부위간 유의한 차이는 없었다.(P>0.05) 결론 : 임플란트 주위 2 mm의 골 결손부위에 자가골 또는 이종골로 채운 경우 유사한 결과를 얻었다. 이 결과 임플란트 fixture 주위의 골 결손부 해소를 위해 자가골을 대체할 수 있는 재료로 $Biocera^{(R)}$를 사용할 수 있음을 보여준다.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.3
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• pp.209-214
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• 2010

Purpose: The purpose of this study was to investigate whether the re-osseointegration of the implants that had mechanical unscrewing possibly occurred or not. Furthermore, if it happened, the degree of re-osseointegration was evaluated by comparing with previous osseointegration. Materials and methods: The smooth implant (commercial pure titanium 99%) specimens, whose diameter and length was 3.75 mm, 4 mm, respectively were produced. Two implants were inserted into each tibia of 7 New Zealand female white rabbits weighing at least 3.0 kg. The torque removal force for each implant after 6 weeks of implants placement was measured and included in group I. The torque removal forces were assessed after the fixtures were re-screwed to original position and the subjects were allowed to have 4 more weeks for healing and included in group II. One rabbit was sacrificed after first measurement and produced 4 slide specimens in group I, and two rabbits were sacrificed after 2nd measurement, 7 slide specimens, in group II for histomorphologic investigations. All slide specimens were assessed based on the proportion of BIC (bone-implant contact) as well as CBa (Bone area in the cortical passage) value produced by counting the screw threads embedded in the compact bones under the optical microscopic analysis (${\times}20$). Statistical analysis was conducted to evaluate the torque removal force, BIC and CBa between group I and II. Results: As for the torque removal force, the result was $10.8{\pm}3.6$ Ncm for group I and $20.2{\pm}9.7$ Ncm for group II. Furthermore, the torque removal force of group II increased by 98.1% in average compared to group I (P<.05). On the other hand, histomorphologic analysis displayed that there was no statistical significance in BIC and CBa values between group I and the group II (P>.05), and RT/BIC and RT/CBa between group I and group II were statistically significant (P<.05). Conclusion: It is possible to obtain more substantial re-osseointegration within shorter periods than the period needed for the initial osseointegration in case of iatrogenically unscrewed implants.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.3
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• pp.190-198
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• 2013

Purpose: The purposes of this study were to investigate osseointegration around zirconia implants which had machined or alumina sandblasted surface, and to compare the results with titanium implants. Materials and methods: The study was performed on the tibia of 6 pigs. Three types of implants were investigated: group T-titanium implant, group Z-machined zirconia implant, group ZS-alumina sandblasting treated zirconia implant. Zirconia implants were manufactured from yttria-stabilized tetragonal zirconia polycrystalline (Acucera Inc., Pocheon, Korea). A total of 36 implants were installed in pigs' tibias. After 1, 4 and 12 weeks of healing period, the periotest and the histomorphometric analysis were performed. The data were analyzed using one-way ANOVA and significance was assessed by the Scheffe test (${\alpha}=.05$). Results: In the measurement of surface roughness, highest Ra value was measured in group T with significant difference. No significant differences were found among groups regarding Periotest values. After 1 week, in comparison of bone to implant contact (BIC), group Z showed higher value with significant difference. In comparison of bone area (BA), group T and group Z showed higher value with significant difference than group ZS. After 4 weeks, in comparison of BIC, group T showed higher value with significant difference. Comparison of BA showed no significant difference among each implant. After 12 weeks, the highest mean BIC values were found in group T with significant difference. Group ZS showed higher BIC value with significant difference than group Z. In comparison of BA, group T and group ZS showed higher value with significant difference than group Z. Conclusion: Zirconia implant showed low levels of osseointegration in this experiment. Modification of surface structure should be taken into consideration in designing zirconia implants to improve the success rate.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.122-127
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• 2010

Purpose: The objective of this study was to investigate the effects of calcium phosphate coated titanium implant surface on bone response and implant stability at early stage of healing period of 3 weeks and later healing period of 6 weeks. Material and methods: A total of 24 machined, screw-shaped implants (Dentium Co., Ltd., Seoul, Korea) which dimensions were 3.3 mm in diameter and 5.0 mm in length, were used in this research. All implants (n = 24), made of commercially pure (grade IV) titanium, were divided into 2 groups. Twelve implants (n = 12) were machined without any surface modification (control). The test implants (n = 12) were anodized and coated with thin film (150nm) of calcium phosphate by electron-beam deposition. The implants were placed on the proximal surface of the rabbit tibiae. The bone to implant contact (BIC) ratios was evaluated after 3 and 6 weeks of implant insertion. Results: The BIC percentage of calcium phosphate coated implants ($70.8{\pm}18.9%$) was significantly higher than that of machined implants ($44.1{\pm}16.5%$) 3 weeks after implant insertion (P = 0.0264). However, there was no significant difference between the groups after 6 weeks of healing (P > .05). Conclusion: The histomorphometric evaluation of implant surface revealed that; 1. After 3 weeks early healing period, bone to implant contact (BIC) percentage of calcium phosphate coated implants (70.8%) was much greater than that of surface untreated machined implants (44.1%) with P = 0.0264. 2. After 6 weeks healing period, however, BIC percentage of calcium phosphate coated implants group (79.0%) was similar to the machined only implant group (78.6%). There was no statistical difference between two groups (P = 0.8074). 3. We found the significant deference between the control group and experimental group during the early healing period of 3 weeks. But no statistical difference was found between two groups during the later of 6 weeks.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.2
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• pp.77-85
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• 2020

Purpose: The aim of the present study was to investigate the effects of N-acetyl cysteine (NAC) loading on the bone formation surrounding sandblasted, large-grit and acid-etched (SLA) implants. Materials and methods: Implantation of NAC loaded SLA implants (NSI group) and SLA implants (SI group) was performed bilaterally in the mandible of 4 adult beagle dogs (each group, n = 8). The animals were sacrificed after a healing period of 3 and 6 weeks, respectively (n = 2 animal each). Dissected blocks were processed for histomorphometrical analysis. Bone to implant contact percentage (BIC%) and bone volume (BV%) were assessed histomorphometrically. Results: BIC% of NAC loaded SLA implants were about 50% higher than that of SLA implants at 3 weeks of bone healing, but not significantly (51.79 vs 35.43%; P=.185). BV% of NAC loaded SLA implants were significantly higher than that of SLA implants at 3 weeks of bone healing (45.09 vs 37.57 %; P=.044). At 6 weeks of bone healing, BIC% and BV% of two experimental groups were similar (P>.05). Conclusion: Within the limits of the present study, NAC loading have a positive effects on the early bone formation surrounding SLA implants. So, it might be concluded that NAC loading enhance the osseointegration and shorten the healing time after implantation of the SLA implants.

• The korean journal of orthodontics
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• v.38 no.3
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• pp.149-158
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• 2008

Objective: The purpose of this study was to investigate the stability of mini-implants in relation to loading time. Methods: A total of 48 mini-implants (ORLUS, Ortholution, Korea) were placed into the buccal alveolar bone of the mandible in 8 male beagle dogs. Orthodontic force (200-250gm) was applied immediately for the immediate loading group while force application was delayed for 3 weeks in the delayed loading group. For the subsequent loading periods (3, 6, 12 weeks), BIC (bone implant contact) and BV/TV (bone volume/total volume) and mobility test were carried out. Results: The immediate loading group showed no changes in BIC from 3 to 12 weeks, while the delayed loading group showed a significant increase in BIC between 3 and 12 weeks (p<0.05). The BV/TO of the delayed loading group significantly increased from 6 to 12 weeks of loading (p<0.05), while the BV/TV of the immediate loading group decreased from 3 to 12 weeks of loading. However, there was no significant difference in BV/TV between experimental groups. The mobility of the immediate loading group was not significantly different from that of the delayed loading group after 12 weeks of loading (p<0.05). Conclusions: These results showed that immediate loading does not have a negative effect on the stability of mini-implants compared to the early loading method in both the clinical and histomorphometric point of view.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.337-349
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• 2008

Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in delayed loading conditions. A total of 36 solid screw implants (diameter 3.75 mm, length 10mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium Implants served as control. Gold crowns were inserted 3 months. Radiographic assessments and stabilitytests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 1 and 3 months after loading. Histological observations and morphometrical measurements were also performed. Of 36 implants, 32 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels (p=0.413) and RFA values. The mean BIC % in the Mg-implants was $54.4{\pm}20.2%$. The mean BIC % in the turned implant was $48.9{\pm}8.0%$. These differences between the Mg-implant and control implant were not statistically significant (P=0.264). In the limitation of this study, bone-to-implant contact (BIC) and bone area of Mg-incorporated oxidized implant were similar to machine-turned implant. The stability analysis showed no significantly different ISQ values and marginal bone loss between two groups. Considering time-dependent bone responses of Mg-implant, it seems that Mg-implants enhanced bone responses in early loading conditions and osseointegrated similarly to cp Ti implants in delayed loading conditions. However, further investigations are necessary to obtain long-term bone response of the Mg-implant in human.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.125-137
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• 2009

There are many reports that these implant surface treatments may affect to cellular reaction in the surface of implant. This study was done by installing the 8 type implant with the variable surface treatment, used or developed, in the mandible of the mature dog to evaluate how the method of surface treatment of the implant can affect to the bone healing by analyzing histologically and histomorphometrically and find out bone healing appearance periodically after installing implant. By using the 8 type implants which have the different surface treatment, 72 implants were installed on the mandible of 9 mature dogs, and 3 dogs were sacrificed on every 2, 4, 8 weeks. After making bone fragment by cutting and managing, we analyzed histologically, then compared with BIC(Bone to implant contact) for the histomorphometrical analysis. In the result of histological analysis, there was large amount of bone formation in good state on the adjacent area of implant in the 2 weeks testing group. At 4 weeks, although there was general bone formation, the new bone was separated with the basal bone. At 8 weeks, the new bone became matured and connected tightly to the basal bone. There was no difference in the each surface of 8 implants. In the result of histomorphometrical analysis, 2 weeks group had considerably lower value than 4 and 8 weeks group, and there was no difference between 4 and 8 weeks group. There was no difference in the each surface treatment of implants.