• The korean journal of orthodontics
• /
• v.44 no.5
• /
• pp.246-253
• /
• 2014

Objective: To evaluate the bioactivity, and the biomechanical and bone-regenerative properties of Ti6Al4V miniscrews subjected to anodization, cyclic precalcification, and heat treatment (APH treatment) and their potential clinical use. Methods: The surfaces of Ti6Al4V alloys were modified by APH treatment. Bioactivity was assessed after immersion in simulated body fluid for 3 days. The hydrophilicity and the roughness of APH-treated surfaces were compared with those of untreated (UT) and anodized and heat-treated (AH) samples. For in vivo tests, 32 miniscrews (16 UT and 16 APH) were inserted into 16 Wistar rats, one UT and one APH-treated miniscrew in either tibia. The miniscrews were extracted after 3 and 6 weeks and their osseointegration (n = 8 for each time point and group) was investigated by surface and histological analyses and removal torque measurements. Results: APH treatment formed a dense surface array of nanotubular TiO2 layer covered with a compact apatite-like film. APH-treated samples showed better bioactivity and biocompatibility compared with UT and AH samples. In vivo, APH-treated miniscrews showed higher removal torque and bone-to-implant contact than did UT miniscrews, after both 3 and 6 weeks (p < 0.05). Also, early deposition of densely mineralized bone around APH-treated miniscrews was observed, implying good bonding to the treated surface. Conclusions: APH treatment enhanced the bioactivity, and the biomechanical and bone regenerative properties of the Ti6Al4V alloy miniscrews. The enhanced initial stability afforded should be valuable in orthodontic applications.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.2
• /
• pp.178-183
• /
• 2001

Since the introduction of the concept of osseointegration, the success rate of dental implant has increased dramatically. So, the uses of dental implant in the treatment of partially or fully edentulous patients have played an important role in dental rehabilitation. Regardless of high success rate of dental implant, some amounts of fixtures cannot help failing. We can classify dental implant failure according to timing, causative factor, etc. This study is focused on dental implant fixture failure, occurring during preprosthetic stage. There are various reasons that cause implant failure on this periods, such as improper patient selection, poor bone quality, and periimplantitis, etc. We investigate the survival rate of 1058 fixtures, which installed in 306 patients in our clinic from January 1997 to December 1999, according to type, sex, location, fixture length and width, using Kaplan-Meier product-limit method and to compare each other with log-rank test. Overall survival rate was 96.80%, and 33 implants failed over the preprosthetic stage. Our survey data identified posterior location of mandible as being associated with implant failure(P<0.05).

• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.1
• /
• pp.101-127
• /
• 1993

The purpose of this study was to observe the effects of early loading on the surrounding bone tissue of the implants. 12 ITI HS implants (8 mm) were inserted on the mandible at 3 mongrel dogs. The implants were divided into two groups; the functional group was functioned with crown, and nonfunctional group was functioned without crown. After 3 and 5 months animals were sacrificed and specimens were examined using radiography, light microscopy, scanning electron microscopy. The following results were obtained. 1. On light microscopic and scanning electron microscopic examination, the difference in the amounts of bone attachment between 3 months loaded and unloaded implants were a little. Sometimes more bone attachment were observed in loaded implants. 2. Many osteoids surrounded the fibrous connective tissues indicating of bone remodeling were observed along the outer surface of the implants. 3. On clinical, radiographic, microscopic examination, epithelial downgrowths were not observed and bone attachments to the outer surface of the implants were observed in 3 months loaded and unloaded implants with good oral hygiene. 4. Epithelial downgrowths and crater-like bone resorptions were observed on 5 months loaded and unloaded implants with poor oral hygiene. 5. Many inflammatory cells in the epithelial tissue were packed in the hollow on 5 months loaded implants.

• Journal of Periodontal and Implant Science
• /
• v.33 no.4
• /
• pp.717-728
• /
• 2003

This study was performed to evaluate the difference of the bone-to-implant contact according to the surface roughness of the implants. Two beagles were used in the experiment. Extraction of the all premolars was performed in the mandible. In 3 months of healing, screw-shaped pure titanium machined surface implants (Implantium(R), Dentium Co. Korea), implants blasted with 45${\mu}m$ $TiO_2$ particles, (Implantium(R), Dentium Co. Korea) and implants blasted with 100${\mu}m$ $TiO_2$ particles (Implantium(R), Dentium Co. Korea) in diameter 3.4mm and length 6mm were installed in the edentulous mandible. Each dog was sacrificed at 4, 12 weeks after placement and then nondecalcified specimens were prepared for histologic analysis. The results of this study were as follows. 1. At 4 , 12 weeks after the surgery, bone-to-implant contact in the surface blasted with $TiO_2$ particles was higher than that in the pure titanium machined surface respectively. 2. Osseointegration in the surface blasted with 45${\mu}m$ $TiO_2$ particles was more increased than that in the surface blasted with 100${\mu}m$ $TiO_2$ particles. 3. Bone-to-implant contact was increased with time independent of surface roughness. 4. Bone formation was in the outfolded area more than inside the threads independent of surface roughness. From the above results, we were able t o find the most bone-to-implant contact in 45${\mu}m$ $TiO_2$ blasted implant.

• Journal of Periodontal and Implant Science
• /
• v.33 no.4
• /
• pp.651-671
• /
• 2003

The influence of calcium phosphate (Ca-P) coating on the bone response of titanium implants was investigated two types of titanium implants, i.e. as -machined ,as -machined with Ca-P coating, were prepared. The Ca-P coating produced by OCT Inc technique. These implants were inserted into the left and right femur of beagle dog, After implantation periods of 3 days, 1weeks, weeks, 4weeks, 8weeks, 12weeks. 24weeks, the bone-implant interface was evaluated histologically, histomorphometrically , and removal torque. Histological evaluation revealed no new bone formation around different implant materials after 2weeks of implantation. After 4 weeks, Ca-P coated implants showed a higher amount of bone contact than either of the non coated implants. After 12weeks, bone healing was almost completed. And implant were removed by reverse torque rotation with torque-measuring device. Mean torque values for 4weeks control were 2.375Kgf.cm and experimental were 2.725Kgf.cm. And mean torque values for 8weeks control were 1.25Kgf.cm and experimental were 1.0Kgf.cm On the basis of these findings, we concluded that deposition of a Ca-P coating on an implant has a beneficial effect on the bone response to this implant during the healing phase. Besides implant surface conditions the bone response is also determined by local implant site condition.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.2
• /
• pp.110-115
• /
• 2016

PURPOSE. The purpose of this study was to compare the removal torques of a chemically modified SLActive implant and a blasted, laser-treated (BLT) implant, which were soaked in saline for 2 weeks after their surface modifications. The removal torques of the two implants were measured 4 weeks after their implantation into the bone defect area in rabbit tibias with concentrated growth factor (CGF) application. MATERIALS AND METHODS. To make artificial bone defects in the cortical layers of both tibias, an 8-mm diameter trephine bur was used. Then, prepared CGF was applied to the bony defect of the left tibia, and the bony defect of the right tibia was left unfilled. Four weeks later, the surgical sites of 16 rabbits were re-exposed. For 8 rabbits, the SLActive implants (Straumann, Switzerland) were inserted in the left tibia, and the BLT implants (CSM implant, Daegu, Korea) were inserted in the right tibia. For other rabbits, the BLT implants were inserted in the left tibia, and the SLActive implants were inserted in the right. Four weeks afger the insertion, torque removal was measured from 4 rabbits exterminated via $CO_2$ inhalation. RESULTS. No significant difference was observed between removal torques of the BLT implant and the SLActive implant (P>.05). CONCLUSION. It was found that BLT surface modification exhibited excellent osseointegration. In addition, CGF application did not affect the insertion and removal torque of the implants.

• Journal of Periodontal and Implant Science
• /
• v.38 no.4
• /
• pp.589-594
• /
• 2008

Purpose: Osseointegration of implants in patients with pneumatized maxillary sinuses is difficult to achieve due to the deficiency of available bone in the posterior maxilla after loss of teeth. Maxillary sinus elevation is a method to overcome this problem. In this study, we evaluated the implant survival rate and the relationship between implant survival in patients with sinus elevation by the lateral approach. Materials and Methods: A total of 48 patients were consecutively treated with sinus elevation by the lateral approach between February 2003 & August 2006 at the dental hospital of Chonbuk National university. A total of 113 implants were placed. The mean healing period was 7.1 months and implants were placed after a mean period of 5.6 months. The mean observation period was 21.8 months. Results: Out of the 113 implants placed, fifteen failed, resulting in a survival rate of 86.7%, 18 cases of sinus membrane perforation were observed out of 65 sinuses treated. 33 implants were placed in a perforated site and 10 failed, representing a 60.7% implant survival. 80 implants were placed in a nonperforated site and 5 failed, representing a 92.6% implant survival. Conclusions: Implant placement with sinus elevation is an acceptable treatment for short term results. Sinus membrane perforation and postoperative complications, however, may have an effect on implant failure.

• Journal of Periodontal and Implant Science
• /
• v.38 no.4
• /
• pp.595-602
• /
• 2008

Purpose: Ti-6Al-4V alloy is widely used as an implant material because of its good biocompatibility and good mechanical property compared with commercial pure titanium. Otherwise, toxicity of aluminum and vanadium in vivo has been reported. Ti-8Ta-3Nb alloy is recently developed in the R&D Center for Ti and Special Alloys and it was reported that this alloy has high mechanical strength, no cytotoxicity and similar biocompatibility to commercial pure titanium, but many studies are needed for its clinical use. In these experiment, we carried out different surface treatment on each Ti-8Ta-3Nb alloy disks, then cultured cell on it and assessed biological response. Materials and Methods: cpTi, Ti-6Al-4V, Ti-8Ta-3Nb alloy disks were prepared and carried out sandblasting and acid etching (SLA) or alkali-heat treatment (AH) on the Ti-8Ta-3Nb alloy disks. We cultured primary rat calvarial cells on each surface and assessed early cell attachment and proliferation by scanning electron microscopy, cell proliferation, alkaline phosphatase activity. Result: The rates of cell proliferation on the cpTi, Ti-8Ta-3Nb AH disks were higher than others (p<0.05) and alkaline phosphatase activity was significantly enhanced on the Ti-STa-8Nb AH disks(p<0.05). Conclusion: Most favorable cell response was shown on the Ti-8Ta-3Nb AH surfaces. It is supposed that alkali-heat treatment of the Ti-8Ta-3Nb alloy could be induced earlier bone healing and osseointegration than smooth surface.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.20 no.1
• /
• pp.31-41
• /
• 2004

The osseointegration in implant therapy is achieved following general wound healing mechanism. Platelet play a major role in wound healing process. In addition to blood clot formation, they secrete many growth factors which regulate the attachment, proliferation and differentiation of nearly all cell types. The use of these growth factors is now known to be very effective methods to improve the cellular activity. Platelet-rich plasma which is made with the newly developed technique concentrating platelets 3-folds or more is also proven to be very effective method to stimulate and accelerate the healing of bone and soft tissue. Previous study proved that platelet-rich plasma enhanced the cellular attachment by inducing fibronectin, vitronectin from osteoblast. So, this study was aimed to investigate the effect of platelet-rich plasma on the cellular proliferation and differentiation in vitro. The effect on the proliferation was evaluated by MTT assay. To evaluate autocrine and paracrine effect, conditioned medium was made and compared. By measuring alkaline phosphatase activity, the effect on the cellular differentiation was evaluated. The results were as following: The cellular proliferation of osteoblast cell line increased depending on the concentration of platelet-rich plasma and conditioned medium. The alkaline phosphatase activity increased depending on the concentration of platelet-rich plasma and conditioned medium. These findings imply that platelet-rich plasma enhance the cellular proliferation and differentiation and maximize the cellular activity by using the autocrine and paracrine effect.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.23 no.1
• /
• pp.31-42
• /
• 2007

The purpose of this study was to compare the stress distribution according to the splinting condition and non-splinting conditions on the finite element models of the two units implant prostheses. The finite element model was designed with the parallel placement of two fixtures ($4.0mm{\times}11.5mm$) on the mandibular 1st and 2nd molars. A cemented abutment and gold screw were used for superstructures. A FEA models assumed a state of optimal osseointegration, as the bone quality, inner cancellous bone and outer 2 mm compact bone was designed. This concluded that the cortical and trabecular bone were assumed to be perfectly bonded to the implant. Splinting condition had 2 mm contact surface and non-splinting condition had $8{\mu}m$ gap between two implant prosthesis. Two group (Splinting and non-splinting) were loaded with 200 N magnitude in vertical axis direction and were divided with subdivision group. Subdivision group was composed of three loading point; Center of central fossa, the 2 mm and 4 mm buccal offset point from the central fossa. Von Mises stress value were recorded and compared in the fixture-bone interface and bucco-lingual sections. The results were as follows; 1. In the vertical loading condition of central fossa, splinting condition had shown a different von Mises stress pattern compared to the non-splinting condition, while the maximum von Mises stress was similar. 2. Stresses around abutment screw were more concentrated in the splinting condition than the non-splinting condition. As the distance from central fossa increased, the stress concentration increased around abutment screw. 3. The magnitude of the stress in the cortical bone, fixture, abutment and gold screw were greater with the 4 mm buccal offset loading of the vertical axis than with the central loading.