Experimental study about the bony healing of hydroxyapatite coating implants

INTRODUCTION: Hydroxyapatite(HA) coating implant can accelerate osseointegration, however, there are many controversies. MATERIALS AND METHODS: This study examined the early osseointegration of two types of hydroxyapatite coated implants. Twelve adult male miniature pigs (Medi Kinetics Micropigs, Medi Kinetics Co., Ltd., Busan, Korea) were used in this study. In the implants placed in the mandible, a histomorphometric evaluation was performed to evaluate the bone-implant contact (BIC) ratio. RESULTS: The BIC ratio increased with time. TS III HA and Zimmer HA were not significantly different (P>0.05). At 8 weeks, the BIC of Zimmer HA was higher than TS III HA, but there was no significant difference (P>0.05). CONCLUSION: HA coated implants will accelerate early osseointegration.

Histomorphometric study of machined titanium implants and calcium phosphate coated titanium implants / 대한치과보철학회지

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 (150 nm) 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 +/- 18.9%) was significantly higher than that of machined implants (44.1 +/- 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.

Comparative Study on Osseointegration of Calcium Metaphosphate (CMP) Coated Implant to RBM Implant in the Femur of Rabbits

The Effects of Citric Acid on HA coated Implant Surface / 대한치주과학회지

The present study was performed to evaluate the effect of citric acid on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, and HA coated surface were utilized. Pure titanium machined surface and HA coated surface were rubbed with pH 1 citric acid for 30s., 45s., 60s., 90s., and 120s. respectively. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. The specimens showed a few shallow grooves and ridges in pure titanium machined surface implants. The roughness of surfaces conditioned with pH 1 citric acid was slightly increased. 2. In HA-coated surfaces, round particles were deposited irregularly. The specimens were not significant differences within 45s. But, began to be changed from 60s. The roughness of surfaces was lessened and the surface dissolution was increased relative to the application time. In conclusion, pure titanium machined surface implants and HA coated surface implants can be treated with pH 1 citric acid for peri-implantitis treatment if the detoxification of these surfaces could be evaluated.

The evaluation of the removal torque and the histomorphometry of the Ca-P coating surface in rabbit tibia / 대한치과보철학회지

STATEMENT OF PROBLEM: Surface texture of the implant is one of the important factors of the implant success, especially in the immediate implant loading. Many methods of the surface treatment of implant have developed and introduced. PURPOSE: This study was to evaluate the effects of the Ca-P coating implant crystallized the hydroxyapatite on the surface by the removal torque test and the histomorphometric analysis in vivo. Material and methods: 135 screw type implants, 4.0mm in length and 3.75mm in diameter were used in this study. Implants were divided into 3 groups and treated in the different methods. Group I was not treated, Group II was treated in the SLA method, and Group III was treated in the Ca-P coating with the anodizing method and the hydroxyapatite was crystallized on the surface with the hydrothermal treatment. Firstly, the surface roughness of each group was measured. 45 rabbits were used in this experiment. Two implants were inserted on right tibial metaphysis and one implant was inserted on left side with the alternating order. After the healing periods of 3, 5, and 12 weeks, the rabbits were sacrificed to evaluate the osseointergration by the removal torque test and the histomorphometric analysis. RESULTS: 1. In the analysis for the surface roughness, Group II showed the highest roughness. And Group III showed higher secondly. There was a significant difference one another statistically. 2. In the removal torque test, Group III and II were significantly higher than Group I. There was no statistical difference between Group III and Group II. 3. For all Groups, the removal torque values at 12th week were significantly higher than at 3rd and 5th week. 4. In histomorphometric analysis, the bone implant contact rates of Group III and II were higher than that of Group I at 3rd and 5th week. There was a significant difference at 5th week. 5. In histomorphometric analysis, the bone implant contact rate of Group III and II increased from 3rd week to 5th week, but decreased at 12th week. In Group I, the contact rate at 12th week was significantly higher than at 3rd week and 5th week.

The Biological Effects of Calcium Phosphate Coated Implant for Osseointegration in Beagle Dogs / 대한치주과학회지

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.

Healing of the Bone around Hydroxyapatite-Coated Implants without Primary Bone Contact / 대한치주과학회지

Implant stability is the key to long-term successful outcome for osseointegrated implants. To evaluate the initial healing response of bone around HA-coated implants without primary bone contact. 21 HA-coated thread type implants(STERI-OSS?) were placed in the femurs of 5 mongrel dogs, about 1-year old. Implants, 8 mm in length and 3.8mm(experimental 1group), 5.0mm(experimental 2group) and 6.0mm(control group) in diameter, were inserted after 3 holes of 6.0mm in diameter and 10mm in depth were prepared in the surgical sites each dog. Implants were supported by only non-resorbable membrane(Teflon(R)), in order to prevent the ingrowth of upper soft tissue into the gap between bone and implant, and to maintain each implant to be positioned in the center of the drilled hole. 9 implants with different diameters were inserted in 3 dogs for histologic observation, and 12 implants were inserted in 2 dogs for mobility test and removal torque test. Fluorescent dyes were injected for the observation of new bone formation in order of Terramycin(R), Arizarin Red(R), and Calcein(R) at an interval of 2 weeks. 3 dogs were sacrificed for histologic observation at 4, 8, and 12-week after placement. Light microscopy and confocal laser scanning microscopy were used to qualitatively characterize the bone around HA-coated implant. 2 dogs were sacrificed for mobility test(Periotest(R), Simens AG, Bensheim, Germany) and removal torque test (Autograph(R) AGS-1000D series, Japan) at 8 and 12-week after placement The results were as follows: 1. Histologic observation showed that osseointegration occurred to both control and experimental groups as time lapse, but delayed bone healing was revealed in 3.8mm group (experimental 1group), compared to contrtol group and 5.0mm group (experimental 2group). 2. The mobility test showed that the experimental groups had no distinguishable movement during experimental periods of 8 and 12-week, and there was no difference in mobility depending on the gap between bone and implant, and time lapse. 3. The removal torque forces were increased depended on the gaps decreasing between bone and implant, and time lapse. The results suggest that HA-coated implant without primary bone contact, based on guided bone regeneration could obtain its stability in all experimental groups as time lapse, but bone healing was delayed in experimental group of 3.8mm. And the results suggested that studies on correlationship between mobility test and removal torque test for implant stability would be necessary.

THR with Hydroxyapatite - coated Hip Prosthesis / 대한정형외과학회잡지

Synthetic hydroxyapatite is a safe, nontoxic, biocompatible, and osteoconductive material. Hydroxyapatite-coated implants have the property of achieving a very strong bond with living bone in a relatively short period. From March 1992 to June 1994, 140 hydroxyapatite-coated primary total hip prostheses were implanted. This study included 60 cases that could follow up minimum 3 years. At the time of mean follow up, 45 months after operation, the mean Harris hip score was 92 points. Only two patients complained of thigh pain at last follow up. On radiographic evaluation, radiolucent lines were seen around the uncoated distal part of the stem in 46 percents of the implants. No radiolucent line was observed around the coated area of the prosthesis. Cancellous condensation was seen in 95 per cents of the implants at the Gruen zone 2 and 6 area. Cortical hypertrophy was present in 32 percents. Fourteen cases had the gaps at the bone to acetabular cup interface in the immediate postoperative period. The gaps disappeared in 12 months after operation. Five implants were revised because of polyethylene wear, cup migration and periprosthetic fracture. The clinical outcome was excellent. But this result was obtained in the relatively short-term follow up. Longer-term data will be the only true test of the value of hydroxyapatite coated implant.

Early Postoperative Periprosthetic Radiological Findings in Cementless THRA : Comparison between Porous - coated Implant and Hydroxyapatite - coated Implant / 대한정형외과학회잡지

We compared radiologically two groups of total hip prostheses, 36 porous-coated and 51 hydroxyapatite-coated, which had been implanted in 87 hips of 73 patients with avascular necrosis of the femoral head. Radiographs were taken at postoperative 1 year and 2 year, and used to compare various radiological parameters between the two groups. For the acetabular side radioluscent line and osteolysis were evaluated, and for the femoral side radioluscent line, osteolysis, stress shielding. endosteal new bone formation, subsidence and cortical hypertrophy were evaluated; their location was identified according to the zones described by DeLee and Charnley for the acetabulum and according to those described by Gruen et al for the femur. In both groups there was no subsidence. In terms of osteolysis, stress shielding and cortical hyper-trophy there was no significant difference between the two groups throughout the period. Radioluscent line in the acetabulum was more common around the porous-coated cup, but was focal and not progressive. The rate of radioluscent line in the femur was a little higher around hydroxyapatite-coated stem especially in zone 5. Endosteal new bone formation was excellent in both groups, but was more extensive around hydroxyapatite-coated stem. This study suggests that hydroxyapatite coating play a certain role in terms of bony ingrowth.

Teh Effect of Hydroxyapatite Coating on the Mechanical Strengths and Histologic Profiles of Porous Titanium Implants in Dogs / 대한정형외과학회잡지

The purpose of this study is to investigate the effect of plasma sprayed hydroxyapatite(HA) coating on bone ingrowth into fiber-mesh coated titanium implant. The shear strength of the HA coatings on interface attachment, the degree of osseointegration of HA coated implants and bone ingrowth of fiber-mesh coated titanium implants were evaluated. The implants were placed transcortically in the femora of mature dogs and evaluated after six weeks. The pushout test showed 33.58±10.87 MPa in HA-coated fiber meshed implants and 20.53±4.91 MPa in fiber-mesh coated implants. In histologic observations, similar quantitative results in the amount of bone ingrowth and osseointegration on both systems. The HA coatings showed direct osseointegration and bone ingrowth on its surface and fiber-mesh without fibrous layer, but the fiber-mesh only coatings showed thin fibrous layer between the ingrown bone and titanium surface. In conclusion, HA-coating on fiber-mesh coated implant provided earlier and stronger osseointegration and bone ingrowth than fiber-mesh only coated implant.