Research progress on ossification by titanium nanotube implant modification / 口腔疾病防治

@#Surface modification of titanium implants is a hot topic for improving osteointegration and includes physical, chemical, bioactive and anodization methods. Among these methods, anodization methods can form TiO2 nanotube structures with a uniform and stable structure, and TiO2 nanotubes and substrates have high binding strengths and osteogenic properties and represent an excellent method for implant modification. TiO2 nanotube osteogenesis is closely related to its morphology, diameter and physicochemical characteristics. Therefore, the structure of TiO2 nanotubes with optimal osteogenic performance can be prepared by regulating these factors. At present, research on TiO2 nanotubes is mostly focused on composite treatments with TiO2 nanotubes, namely, the combination of other implant modification methods (physical method, chemical method, biological method) and TiO2 nanotubes to form a composite structure to work synergistically to treat osteogenesis. TiO2 nanotube composite treatment is a good prospective application for the further preparation of TiO2 nanotube-modified structures with strong osteogenic properties.

A Biocompatibility Evaluation of Hydroxyapaite·Titania Surface for Dental Implant / 치위생과학회지

The objective of this study was to fabricate hydroxyapatite (HA) containing titania layer by HA blasting and anodization method to obtain advantages of both methods and evaluated biocompatibility. To fabricate the HA containing titania layer on titanium, HA blasting treatment was performed followed by microarc oxidation (MAO) using the electrolyte solution of 0.04 M β-glycerol phosphate disodium salt n-hydrate and 0.4 M calcium acetate n-hydrate on the condition of various applied voltages (100, 150, 200, 250 V) for 3 minutes. The experimental group was divided according to the surface treatment procedure: SM (simple machined polishing treatment), HA, MAO, HA+MAO 100, HA+MAO 150, HA+MAO 200, HA+ MAO 250. The wettability of surface was observed by contact angle measurement. Biocompatibility was evaluated by cell adhesion, and cell differentiation including alkaline phosphatase activity and calcium concentration with MC3T3-E1 cells. The porous titanium oxide containing HA was formed at 150 and 200 V. These surfaces had a more hydrophilic characteristic. Biocompatibility was demonstrated that HA·titania composite layer on titanium showed enhanced cell adhesion, and cell differentiation. Therefore, these results suggested that HA containing titania layer on titanium was improved biological properties that could be applied as material for dental implant system.

Effect of surface anodization on stability of orthodontic microimplant / 대한치과교정학회지

OBJECTIVE: To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. METHODS: A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. RESULTS: There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 +/- 1.39 Ncm) than for the machined ones (2.05 +/- 1.07 Ncm) (p < 0.01). The interfacial strengths, converted from PRT, were calculated at 10.6 MPa and 5.74 MPa for the anodized and machined group implants, respectively. CONCLUSIONS: Anodization of orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage.

Wettability and cellular response of UV light irradiated anodized titanium surface

PURPOSE: The object of this study was to investigate the effect of UV irradiation (by a general commercial UV sterilizer) on anodized titanium surface. Surface characteristics and cellular responses were compared between anodized titanium discs and UV irradiated anodized titanium discs. MATERIALS AND METHODS: Titanium discs were anodized and divided into the following groups: Group 1, anodized (control), and Group 2, anodized and UV irradiated for 24 hours. The surface characteristics including contact angle, roughness, phase of oxide layer, and chemical elemental composition were inspected. The osteoblast-like human osteogenic sarcoma (HOS) cells were cultured on control and test group discs. Initial cellular attachment, MTS-based cell proliferation assay, and ALP synthesis level were compared between the two groups for the evaluation of cellular response. RESULTS: After UV irradiation, the contact angle decreased significantly (P<.001). The surface roughness and phase of oxide layer did not show definite changes, but carbon showed a considerable decrease after UV irradiation. Initial cell attachment was increased in test group (P=.004). Cells cultured on test group samples proliferated more actively (P=.009 at day 2, 5, and 7) and the ALP synthesis also increased in cells cultured on the test group (P=.016 at day 3, P=.009 at day 7 and 14). CONCLUSION: UV irradiation induced enhanced wettability, and increased initial cellular responses of HOS cells on anodized titanium surface.

Precalcification Treatment of TiO2 Nanotube on Ti-6Al-4V Alloy / 대한치과보철학회지

STATEMENT OF PROBLEM: Recently precalcification treatment has been studied to shorten the period of the implant. Purpose: This study was performed to evaluate the effect of precalcification treatment of TiO2 Nanotube formed on Ti-6Al-4V Alloy. MATERIAL AND METHODS: Specimens of 20 x 10 x 2 mm in dimensions were polished sequentially from #220 to #1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at 50 degrees C for 24 hours. The nanotubular layer was processed by electrochemical anodic oxidation in electrolytes containing 0.5 M Na2SO4 and 1.0 wt percent NaF. Anodization was carried out using a regulated DC power supply (Kwangduck FA, Korea) at a potential of 20 V and current density of 30 mA/cm2 for 2 hours. Specimens were heat-treated at 600 degrees C for 2 hours to crystallize the amorphous TiO2 nanotubes, and precalcified by soaking in Na2HPO4 solution for 24 hours and then in saturated Ca(OH)2 solution for 5 hours. To evaluate the bioactivity of the precalcified TiO2 nanotube layer, hydroxyapatite formation was investigated in a Hanks'balanced salts solution with pH 7.4 at 36.5 degrees C for 2 weeks. RESULTS: Vertically oriented amorphous TiO2 nanotubes of diameters 48.0 - 65.0 nm were fabricated by anodizing treatment at 20 V for 2 hours in an 0.5 M Na2SO4 and 1.0 NaF solution. TiO2 nanotubes were composed with strong anatase peak with presence of rutile peak after heat treatment at 600 degrees C. The surface reactivity of TiO2 nanotubes in SBF solution was enhanced by precalcification treatment in 0.5 M Na2HPO4 solution for 24 hours and then in saturated Ca(OH)2 solution for 5 hours. The immersion in Hank's solution for 2 weeks showed that the intensity of TiO2 rutile peak increased but the surface reactivity decreased by heat treatment at 600 degrees C. CONCLUSION: This study shows that the precalcified treatment of TiO2 Nanotube formed on Ti-6Al-4V Alloy enhances the surface reactivity.

Bone response to a Ca- and P-enriched titanium surface obtained by anodization

This study evaluated bone response to a Ca- and P- enriched titanium (Ti) surface treated by a multiphase anodic spark deposition coating (BSP-AK). Two mongrel dogs received bilateral implantation of 3 Ti cylinders (4.1 x 12 mm) in the humerus, being either BSP-AK treated or untreated (machined - control). At 8 weeks postimplantation, bone fragments containing the implants were harvested and processed for histologic and histomorphometric analyses. Bone formation was observed in cortical area and towards the medullary canal associated to approximately 1/3 of implant extension. In most cases, in the medullary area, collagen fiber bundles were detected adjacent and oriented parallel to Ti surfaces. Such connective tissue formation exhibited focal areas of mineralized matrix lined by active osteoblasts. The mean percentages of bone-to-implant contact were 2.3 (0.0-7.2 range) for BSP-AK and 0.4 (0.0-1.3 range) for control. Although the Mann-Whitney test did not detect statistically significant differences between groups, these results indicate a trend of BSP-AK treated surfaces to support contact osteogenesis in an experimental model that produces low bone-to-implant contact values.

O objetivo desse estudo foi avaliar a resposta do tecido ósseo à superfície de titânio (Ti) enriquecida com Ca e P obtida por anodização (BSP-AK). Três cilindros de Ti (4,1 x 12 mm) BSP-AK ou usinado (controle) foram implantados bilateralmente nos úmeros de dois cães de raça indefinida. Oito semanas após a implantação, os fragmentos ósseos contendo os implantes foram removidos e processados para análises histológica e histomorfométrica. A formação óssea foi observada na região cortical e no canal medular até aproximadamente um terço da extensão do implante. Na maioria dos casos, feixes de fibras colágenas dispostos paralelamente à superfície do implante foram observados na região medular. Nessa região observaram-se também áreas focais de formação de matriz mineralizada e osteoblastos ativos. Os implantes do grupo BSP-AK apresentaram média de contato osso-implante 2,3 por cento, com medidas variando de 0,0 a 7,2 por cento e os do grupo controle tiveram média 0,4 por cento, com medidas variando de 0,0 a 1,3 por cento. Apesar do teste de Mann-Whitney não mostrar diferença estatisticamente significante entre os grupos, nossos resultados indicaram uma tendência para a ocorrência de osteogênese de contato na superfície BSP-AK em um modelo experimental que resulta em baixos valores de contato osso-implante.

The bone formation around anodic oxidized titanium implants in the tinbiae of ovarectomized rats

Anodic spark deposition method(ASD) surface treated titanium implant possesses a considerable osteoconductive potential that promoting a high level of implant osseointegration in normal bone. The purpose of this study was to observe the ASD implant's osseointegration in the osteoporosis-induced animal model. Twenty four rats, 10 weeks of age, were ovarectomized and 5 weeks later divided into two groups : ASD implant group and control implant group. Titanium screw implants (diameter; 2.0 mm, length, 3.5 mm; pitch-height, 0.4 mm) were designed for this study. Experimental implants were ASD treated and no treatment on control implants. ASD implants and control implants were placed in to left tibiae of rats. The rats were sacrificed at different time interval(1, 2, 4 and 8 weeks after implantation) for histopathologic observation and immunohisto -chemistrical observation, with collagen type I, fibronectin, integrin alpha2beta1 and integrin alpha5beta1 antibodies. The results obtained from this study were as follow: 1. Histopathologic findings, overall tissue response and the pattern of bone formation in both groups were similar. In ASD group, more newly formed bone was seen at 1 week and 2weeks than control group. 2. The levels of type I collagen and fibronectin expression were the most abundant at 2weeks and decreased gradually in both groups. Fibronectin and type I collagen expression in ASD group were stronger than control group but no significance. 3. The levels of integrin alpha2beta1 and Integrin alpha5beta1 expression were most abundant at 2 weeks and decreased gradually in both groups. No significant difference was observed in both groups. From this results, anodic oxidized titanium implants were more advantages in early stage of bone formation than control group, but have no significance in tissue responses and late bone formations. It could be stated that although anodic oxidized titanium implant possesses considerable osteoconductive potential but in osteoporotic bone condition dental implant procedure should performed after improving or treating the osteoporotic bone condition.

Intradermal stimulus and sensitivity response for new kinds of Mg alloy / 中国矫形外科杂志

[Objective] To evaluate the biocompatibility in vivo of Mg alloy AZ91D(AZ0),Mg-Mn-Ce(RE0)and their step anodizational materials(AZ1,AZ2,AZ3,RE1,RE2,RE3)by the experiments of intradermal stimulus and sensitivity response.[Methods]According toGB/T 16886.10-1997 Biological Evaluation of Medical Apparatus and Instrument,compared with normal sodium,pure magnesium and medical Ti-6Al-7Nb,the leaching liquor were injected into cutis to evaluate stimulus response,to evaluate sensitivity response by injection and illinition.[Results]RE2 could not prepare leaching liquor,it's kicked out.Intradermal stimulus response:normal sodium,Ti-6A1-7Nb,AZ1,AZ3 groups inflammation responded as degree I,scored 0.The others inflammation responded as degree Ⅱ,scored 1.Sensitivity response:formaldehyde group inflammation responded as degree IV,erythema and edema were degree IV.Normal sodium group inflammation responded as degree I,erythema and edema were degree 0.Ti-6Al-7Nb,AZ1,AZ3 groups inflammation responded as degree Ⅱ,erythema and edema were degree 1.The others inflammation responses were degree Ⅲ,erythema and edema were degree Ⅱ.[Conclusion]The new kinds of magnesium alloy AZ1,AZ3 possesses good preliminary biocompatibility in vivo,so it is very possible to be a new type of bone surgery implant material.

Biological responses of osteoblast-like cells to different Titanium surface by anodizing modification / 대한치과보철학회지

STATEMENT OF PROBLEM: To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. The surface quality of the implant depends on the chemical, physical, mechanical and topographical properties of the surface. The different properties will interact with each other and a change in thickness of the oxide layer may also result in a change in surface energy, the surface topography and surface, chemical composition. However, there is limited the comprehensive study with regard to changed surface and biologic behavior of osteoblast by anodization. PURPOSE OF STUDY: The aim of this study was to analyze the characteristics of an oxide layer formed and to evaluate the cellular biologic behaviors on titanium by anodic oxidation (anodization) by cellular proliferation, differentiation, ECM formation and gene expression. And the phospholipase activity was measured on the anodized surface as preliminary study to understand how surface properties of Ti implant are transduced into downstream cellular events. METHODS AND MATERIALS: The surface of a commercially pure titanium(Grade 2) was modified by anodic oxidation. The group 1 samples had a machined surface and other three experimental specimens were anodized under a constant voltage of 270 V(Group 2), 350 V(Group 3), and 450 V(Group 4). The specimen characteristics were inspected using the following five categories; the surface morphology, the surface roughness, the thickness of oxide layer, the crystallinity, and the chemical composition of the oxide layer. Cell numbers were taken as a marker for cell proliferation. While the expression of alkaline phosphatase and Runx2 (Cbfa1) was used as early differentiation marker for osteoblast. The type I collagen production was determined, which constitutes the main structural protein of the extracellular matrix. Phospholipase A2 and D activity were detected. Results. (1) The anodized titanium had a porous oxide layer, and there was increase in both the size and number of pores with increasing anodizing voltage. (2) With increasing voltage, the surface roughness and thickness of the oxide film increased significantly (p<0.01), the TiO2 phase changed from anatase to rutile. During the anodic oxidization, Ca and P ions were more incorporated into the oxide layer. (3) The in vitro cell responses of the specimen were also dependant on the oxidation conditions. With increasing voltage, the ALP activity, type I collagen production, and Cbfa 1 gene expression increased significantly (p<0.01), while the cell proliferation decreased. (4) In preliminary study on the relation of surface property and phospholipase, PLD activity was increased but PLA2 activity did not changed according to applied voltage. CONCLUSION: The anodized titanium shows improved surface characteristics than the machined titanium. The surface properties acquired by anodization appear to give rise more mature osteoblast characteristics and might result in increased bone growth, and contribute to the achievement of a tight fixation. The precise mechanism of suface property signaling is not known, may be related to phospholipase D.