• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.1-9
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• 2018

Purpose: The purpose of this study is to investigate the effect of the titanium implant soaked in saline after RBM and acid etched surface treatment on the initial osseointegration by comparing the removal torque and the surface analysis compared to the titanium implant with only RBM and acid etched surface treatment. Materials and Methods: The control group was RBM and acid etched surface treated implants (RBM + HCl), and the test group was implants soaked in saline for 2 weeks after RBM and acid etched surface treatment (RBM + HCl + Sal). The control and test group implants were placed in the left and right tibiae of 10 rabbits, respectively, and at the same time, the insertion torque (ITQ) was measured. After 10 days, the removal torque (RTQ) was measured by exposing the implant site. FE-SEM, EDS, Surface roughness and Raman spectroscopy were performed for the surface analysis of the new implant specimens used in the experiments. Results: There was significant difference in insertion torque and removal torque between control group and experimental group (P = 0.014 < 0.05). Surface roughness of experimental group is higher than control group. Conclusion: Saline soaking after RBM and acid etched surface treatment of titanium implants were positively affect the initial osseointegration as compared to titanium implants with only RBM and acid etched surface treatment.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.6
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• pp.269-273
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• 2013

Objectives: This study is designed to evaluate the mechanical stability of orthodontic mini-implants with vertical grooves in rabbits. Materials and Methods: This study was done from March 2011 to February 2012 in Dental Research Institute of Seoul National University. Thirty-two mini-implants in the control group and 32 in the rotation bump (RB) group were inserted in the tibias of 16 rabbits and were removed after two weeks and four weeks, respectively. The maximum insertion torque (MIT), maximum removal torque (MRT), torque ratio (TR) of MRT to MIT and removal angular momentum (RAM) were all measured at the time of removal. Results: There were no significant differences between the two groups in MIT and MRT at two weeks or four weeks. However, TR and RAM at four weeks in the RB group were significantly higher than in the control group (P<0.05). TR of the RB group was significantly increased at four weeks (P<0.05). In both groups, RAM at four weeks was significantly higher than at two weeks (P<0.05). Conclusion: These results suggest that RB of the mini-implant could provide resistance to the removal rotation, although it did not increase the MRT.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.136-142
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• 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.

• The korean journal of orthodontics
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• v.40 no.3
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• pp.167-175
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• 2010

Objective: The aim of this study was to validate the Periotest values for the prediction of orthodontic mini-implants' stability. Methods: Sixty orthodontic mini-implants (7.0 mm $\times$ $\emptyset1.45$ mm; ACR, Biomaterials Korea, Seoul, Korea) were inserted into the buccal alveolar bone of 5 twelve month-old beagle dogs. Insertion torque (IT) and Periotest values (PTV) were measured at the installation procedure, and removal torque (RT) and PTV were recorded after 12 weeks of orthodontic loading. To correlate PTV with variables, the cortical bone thickness (mm) and bone mineral density (BMD) within the cortical bone and total bone area were calculated with the help of CT scanning. Results: The BMD and cortical bone thickness in mandibular alveolus were significantly higher than those of the maxilla (p < 0.05). The PTV values ranged from -3.2 to 4.8 for 12 weeks of loading showing clinically stable mini-implants. PTV at insertion was significantly correlated with IT (-0.51), bone density (-0.48), cortical bone thickness (-0.42) (p < 0.05) in the mandible, but showed no correlation in the maxilla. PTV before removal was significantly correlated with RT (-0.66) (p < 0.01) in the mandible. Conclusions: These results show that the periotest is a useful method for the evaluation of mini-implant stability, but it can only be applied to limited areas with thick cortical and high density bone such as the mandible.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.701-702
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• 2008

An adaptive response surface method with Latin Hypercube sampling strategy is employed to optimize a magnet pole shape of large scale BLDC motor to minimize the cogging torque. The proposed algorithm consists of the multi-objective Pareto optimization and (1+${\lambda}$) evolution strategy to find the global optimal points with relatively fewer sampling data. In the adaptive RSM, an adaptive sampling point insertion method is developed utilizing the design sensitivities computed by using finite element method to get a reasonable response surface with a relatively small number of sampling points. The developed algorithm is applied to the shape optimization of PM poles for 6 MW BLDC motor, and the cogging torque is reduced to 19% of the initial one.

• The korean journal of orthodontics
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• v.46 no.6
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• pp.386-394
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• 2016

Objective: The objective of the study was to evaluate the practicality and the validity of different surface treatments of self-drilling orthodontic mini-implants (OMIs) by comparing bone cutting capacity and osseointegration. Methods: Self-drilling OMIs were surface-treated in three ways: Acid etched (Etched), resorbable blasting media (RBM), partially resorbabla balsting media (Hybrid). We compared the bone cutting capacity by measuring insertion depths into artificial bone (polyurethane foam). To compare osseointegration, OMIs were placed in the tibia of 25 rabbits and the removal torque value was measured at 1, 2, 4, and 8 weeks after placement. The specimens were analyzed by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Results: The bone cutting capacity of the etched and hybrid group was lower than the machined (control) group, and was most inhibited in the RBM group (p < 0.05). At 4 weeks, the removal torque in the machined group was significantly decreased (p < 0.05), but was increased in the etched group (p < 0.05). In the hybrid group, the removal torque significantly increased at 2 weeks, and was the highest among all measured values at 8 weeks (p < 0.05). The infiltration of bone-like tissue surface was evaluated by SEM, and calcium and phosphorus were detected via EDS only in the hybrid group. Conclusions: Partial RBM surface treatment (hybrid type in this study) produced the most stable self-drilling OMIs, without a corresponding reduction in bone cutting capacity.

• Journal of Periodontal and Implant Science
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• v.39 no.3
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• pp.339-348
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• 2009

Purpose: The purpose of the present study was to analyze the implant stability quotient(ISQ) values for Korean non-submerged type implant and determine the factors that affect implant stability. Methods: A total of 49 Korean non-submerged type implants were installed in 24 patients, and their stability was measured by resonance frequency analysis(RFA) at the time of surgery, and 1, 2, 3, 4, 8, 12 weeks postoperatively. The data for implant site, age, sex, implant length and diameter, graft performing, bone type, and insertion torque were analyzed. Results: The lowest mean stability measurement was at 3 weeks. There was significant difference between implant placement and 12 weeks. There was significant difference between implant placement and 12 weeks in diameters of 4.1 mm and 4.8 mm. Also, there were significant differences between diameters of 4.1 mm and 4.8 mm at implant placement and 12 weeks after surgery. This result suggests that the factor related to implant diameter may affect the level of implant stability. No statistically significant relationship was found between the resonance frequency analysis and the variables of maxilla/mandible, sex, anterior/posterior, implant length, age of patient, graft performing, bone type, insertion torque during initial healing period. Conclusions: These findings suggest that the factor related to implant diameter may affect the variance of implant stability, and ISQ value of implant was stable enough for proved stability level during initial healing period.

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.83-88
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• 2020

PURPOSE. The purpose of this in vitro study was to examine the reliability of the Anycheck device and the effect of the healing abutment diameter on the Anycheck values (implant stability test, IST). MATERIALS AND METHODS. Thirty implants were placed into three artificial bone blocks with 10 Ncm, 15 Ncm, and 35 Ncm insertion torque value (ITV), respectively (n = 10). (1) The implant stability was measured with three different kinds of devices (Periotest M, Osstell ISQ Mentor, and Anycheck). (2) Five different diameters (4.0, 4.5, 4.8, 5.5, and 6.0 mm) of healing abutments of the same height were connected to the implants and the implant stability was measured four times in different directions with Anycheck. The measured mean values were statistically analyzed. RESULTS. The correlation coefficient between the mean implant stability quotient (ISQ) and IST value was 0.981 (P<.01) and the correlation coefficient between the meant periotest value (PTV) and IST value was -0.931 (P<.01). There were no statistically significant differences among the IST values with different healing abutment diameters. CONCLUSION. There was a strong correlation between the Periotest M and Anycheck values and between the ISQ and IST. The diameter of the healing abutment had no effect on the Anycheck values.

• Journal of Korean Dental Science
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• v.4 no.2
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• pp.52-58
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• 2011

Purpose: Modifications of implant design have been related to improving initial stability. The purpose of this study was to investigate their respective effect on initial stability between two tapered implant systems (self-tapping vs. non-self-tapping) in medium density bone using three different analytic methods. Materials and Methods: Self-tapping implant (GS III$^{(R)}$; Osstem Implant Co., Busan, Korea) and non-self-tapping implant (Replace Select$^{(R)}$; Nobel Biocare, G$\H{o}$teborg, Sweden) were investigated. In Solid rigid polyurethane blocks of artificially simulated Quality 2 bone, each of the 5 implants was inserted according to the manufacturer's instructions for medium-bone drilling protocol. Evaluation of initial stability was carried out by recording the maximum insertion torque (IT) and performing the resonance frequency analysis (RFA), and the pull-out test. Results: The IT and RFA values of self-tapping implant were significantly higher than those of non self-tapping implant (P=.009 and P=.047, respectively). In the pull-out values, no significant differences were found in implants between two groups (P=.117). Within each implant system, no statistically significant correlation was found among three different outcome variables. Conclusions: These findings suggest that design characteristics of implant geometry significantly influence the initial stability in medium bone density.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.228-239
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• 2008

Objective: The aim of this study was to evaluate the strain induced in the cortical bone surrounding an orthodontic microimplant during insertion. Methods: A 3D finite element method was used to model the insertion of a microimplant (AbsoAnchor SH1312-7, Dentos Co., Daegu, Korea) Into 1 mm thick cortical bone with a pre-drilled hole of 0.9 mm in diameter. A total of 1,800 analysis steps was used to simulate the 10 turns and 5 mm advancement of the microimplant. A series of remesh in the cortical bone was allowed to accommodate the change in the geometry accompanied by the implant insertion. Results: Bone strains of well higher than 4,000 microstrain, the reported upper limit for normal bone remodeling, was observed in the bone along the whole length of the microimplant. At the bone in the vicinity of the screw tip, strains of higher than 100% was recorded. The insertion torque was calculated at approximately 1.2 Ncm which was slightly lower than those measured from the animal experiment using rabbit tibias. Conclusions: The insertion process of a microimplant was successfully simulated using the 3D finite element method which showed that bone strains from a microimplant insertion might have a negative impact on physiological remodeling of bone.