Effect of modern techniques of sterilization on the surface by pptfiles

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									Comparison of the surface characteristics of dental implant after sterilization by gamma radiation as compared to other sterilization techniques By

Dr AbdelAziz Al-Khorif Assistant professor and head of the dental Department, College of Applied medical science, King Saud University Prof. Khaled M. El-Sayed Professor Oral & Maxillofacial Surgery, College of Dentistry, King Saud University Dr. Mohamed I. Hashim Assistant professor, Dental Department, College of Applied medical science, King Saud University

Introduction:
Since Branemark et al. described the osseointegration effect [1] almost four decades ago, several biomedical and materials researchers have tried to design the ideal surface for ensuring long-lasting anchorage of implants. Besides implant shape (macro-scale), surface properties on micro and nanometric scale can affect the formation of adjacent bones. However, the surface properties (composition, energy and topography) are interrelated [2], and consequently, it is very difficult to determine how coatings or surface modifications, or both, individually affect osseointegration. Thus, manufacturers have continuously developed new implants involving macrodesign and surface treatment using clinical trials. These implants are usually evaluated by in vivo tests using rabbits or dogs [3] and [4]. The effect of sterilization on the bulk and surface properties of biomaterials has been under investigation by many researchers [5,6, 7, 8 and 9] because sterilization, the last step of the processing of any implant material, may have an important clinical impact. However, the question of how the surface modifications may influence mineralization of biomaterials used as implant devices for substitution of bone tissue was scarcely addressed. There are many sterilization technique that has been used for a long time in dentistry and surgery. The most commonly used sterilization processes for implant materials are steam autoclaving and γ-irradiation which are considered to be safe with respect to chemical contamination of the surface, in contrast with, e.g. sterilization with ethylene oxide or with aqueous glutaraldehyde solution used for sterilizing medical tools. Another promising sterilization method that is now receiving attention from the biomaterials community is glow plasma discharge. The modification of Ti surfaces induced by steam autoclaving was reported by Vezeau et al. [10] The thickness of the TiO2 surface layer as well as the level of organic contamination were found to increase after the treatment. Aronsson et al. [5] presented a detailed study on the effect of plasma treatment of metallic biomaterials. For titanium samples covered with the native oxide, they found that cleaning with a low energy Ar plasma led to the reduction of the total amount of surface contaminants, but did not affect significantly the oxide thickness. The effect of γ-radiation on passivated titanium was studied by Schulze et al. [11]. These authors simulated the γ-radiation by UV-laser and found that the amorphous titanium oxide that covered the original passivated surface was transformed in a two-layer system: a recrystallized anatase layer with an amorphous layer on top.

Recently two other modalities of sterilization techniques have been introduced to our specialty. These include laser and ultraviolet light sterilization.Schwartz et al. [12] studied the effect of re-using cover screws for dental implants (Brånemark) and the influence of re-use on clinical outcome. Nine patients, each receiving 3 implants in either the maxilla or the mandible, received 1 new cover screw, 1 re-used coverscrew, and a third coverscrew that had been used multiple times. In all cases, the

re-used cover screws had been washed, mechanically cleaned, and steamsterilized prior to re-implantation. Clinical outcome was assessed by X-ray analysis of the mandible/maxilla and light microscopy of histologically prepared sections of the overlying tissue. The surfaces of the cover screws were characterized by profilometry, scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and atomic force microscopy (AFM). They found that There was no difference in clinical outcome whether the cover screws were new or re-used multiple times. Histological evaluation showed no influence of re-use on the overlying epithelial and connective tissues at the time the cover screw was removed. Surface topography and roughness changed with increasing number of uses, but surface chemistry was virtually unchanged. SEM and AFM analyses revealed the presence of machining marks, as well as deep scratches, across the surface of the re-used cover screws. This study shows that cover screws can be cleaned and re-used without any apparent adverse affect on clinical outcome Vezeau et al. [10]evaluated the surface changes and effects on invitro cell attachment and spreading brought about on prepared commercially pure titanium by multiple exposures to common sterilization methods. Samples underwent sterilization by exposure to ultraviolet light; ethylene oxide sterilization (1, 5, or 10 cycles); or by steam autoclaving (1, 5, or 10 cycles). They reported that Ultraviolet (UV) sterilized surfaces showed no changes from the unsterilized state macroscopically or under SEM. UV surfaces showed cell attachment levels similar to control surfaces at all intervals, and a chronologic progression of cell spreading. Ethylene oxide-sterilized surfaces showed occasional bluish discoloration and a microscopic particulate contaminant, resulting in modest decreases in cell attachment levels without strong correlation to numbers of sterilization cycles. Autoclaved surfaces generally showed the greatest discoloration and heaviest particulate contamination. Cell attachment levels were lower, and cell spreading was diminished compared with the ethyleneoxide-treated group Furthermore the effect of sterilization on mineralization of titanium implant had been studied by Serro and Saramago.[13] Titanium samples were submitted to the following sterilization processes used for implant materials: steam autoclaving, glow discharge Ar plasma treatment and gamma-irradiation. They observed that the most significant modifications were detected on the wettability: while the samples treated with Ar plasma became highly hydrophilic (water contact angle approximately 0 degrees), gamma-irradiation and steam sterilization induced an increase in the hydrophobicity

Aim of the study
The aim of the present work is to compare the surface characteristics of commercially available titanium implants after sterilization by gamma radiation; steam autoclaving; ethylene oxide; ultraviolet light and laser

Material and methods

Commercially available titanium dental implant will be used as a test material. Six untreated implant will be used as a control representing group C. The experimental group ( EG) will be divided into 5groups. In all experimental groups the implant will be unpacked and immersed in simulated body fluid to contaminate it. According to the method of sterilization the implants will be divided into 5 groups each group will contain 18 implant. Each group will be subdivided into three subgroups according to the number of sterilization cycles 1, 5, 10 cycle. EG 1. sterilization EG 2. sterilization EG 3. sterilization EG 4. sterilization EG 5. sterilization by exposure by exposure by exposure by exposure by exposure to steam autoclaving ethylene oxide ultraviolet light Laser Gamma radiation

Representative surfaces from these sterilization groups will be examined using a series of surface analytical techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and contact angle measurements. Cell attachment assays using murine fibroblasts will be performed on titanium surfaces from each sterilization group and on tissue culture plastic controls. Mean percent cell attachment values for each group will be obtained for periods of up to 1 hour. The data will be collected and analysed

References 1. Branemark, R. Adell, U. Breine, B.O. Hansson, J. Lindstrom and A. Ohlsson, Intraosseous anchorage of dental prostheses. I. Experimental studies, Scand J Plast Reconstr Surg 3 (1969), pp. 81–100. 2.. Jones F.H. Teeth and bones: applications of surface science to dental materials and related biomaterials, Surf Sci Rep 42 (2001), pp. 75–205. 3. Barewal RM,. Oates T.W,. Meredith N and Cochran D.L. Resonance frequency measurement of implant stability in vivo on implants with sandblast and acid-etched surface, Int J Oral Maxillofac Implants 18 (2003), pp. 641–651. 4. Cooper L.F. A role for surface topography in creating and maintaining bone at titanium endosseous implants, J Prosthet Dent 84 (2000), pp. 522–534. 5.. Aronsson O, Lausmaa J.and. Kasemo B. Glow discharge plasma treatment for surface cleaning and modification of metallic biomaterials. J Biomed Mater Res 35 (1997), pp. 49–73. 6. Kipaldi D.V, Raikar G.N., Liu J, Lemons J.E,. Vohra Y and Gregory J.C. Effect of surface treatment on unalloyed titanium implants: spectroscopic analyses. J Biomed Mater Res 40 (1997), pp. 646–659. 7.. Kasemo B and. Lausmaa J. Biomaterial and implant surfaces: on the role of cleanliness, contamination and preparation procedures. J Biomed Mater Res 22 (1988), pp. 145–158. 8. Thierry B., Tabrizian M., Savadogo O.and Yahia L’.H. Effects of sterilization processes on NiTi alloy: surface characterization. J Biomed Mater Res 49 (2000), pp. 88–98. 9. Kawahara D., Ong J.L.,. Raikar G.N,. Lucas L.C, Lemons J. and. Nakamura M. Surface characterization of radio-frequency glow discharged and autoclaved titanium surfaces. Int J Oral Maxillofac Implants 11 (1996), pp. 435–442. 10. Vezeau P.J, G.F. Koorbush, R.A. Draughn and J.C. Keller, Effects of multiple sterilization on surface characteristics and in vitro biologic responses to titanium. J Oral Maxillofac Surg 54 (1996), pp. 738–746.

11. Michaelis A., Kudelka S.and Schulze J.W. Effect of γ-radiation on the passive layers of Ti and TiO·2Pd container materials for high-level waste disposal. Electrochim Acta 43 (1998), pp. 119–130.

12. Schwartz Z, Lohmann CH, Blau G, Blanchard CR, Soskolne AW, Liu Y, Cochran DL, Dean DD, Boyan BD. Re-use of implant cover screws changes their surface properties but not clinical. Clin Oral Implants Res. 2000 Jun;11(3):183-94. 13. Serro AP, Saramago B. Influence of sterilization on the mineralization of titanium implants induced by incubation in various biological model fluids. Biomaterials. 2003 Nov;24(26):4749-60.

Summery Osteointegraction of dental implant dependd largely on the surface characteristics of the implant. Because sterilization, the last step of the processing of any implant material, may have an important clinical impact. However, the question of how different technique s of sterilization induce the surface modifications that may influence mineralization of biomaterials used as implant devices for substitution of bone tissue. There are many sterilization technique that has been used for a long time in dentistry and surgery. The most commonly used sterilization processes for implant materials are steam autoclaving and γ-irradiation which are considered to be safe with respect to chemical contamination of the surface. in contrast with, e.g. sterilization with ethylene oxide or with aqueous glutaraldehyde solution used for sterilizing medical tools. Another promising sterilization method that is now receiving attention from the biomaterials community is glow plasma discharge The aim of the present work is to assess the effect different techniques of sterilization on the surface characteristics of commercially available titanium implants. Commercially available titanium dental implant will be used as a test material. Six untreated implant will be used as a control representing group C. The experimental group ( EG) will be divided into 5groups. In all experimental groups the implant will be unpacked and immersed in simulated body fluid to contaminate it. According to the method of sterilization the implants will be divided into 5 groups each group will contain 18 implant. Each group will be subdivided into three subgroups according to the number of sterilization cycles 1, 5, 10 cycle. EG 1. sterilization EG 2. sterilization EG 3. sterilization EG 4. sterilization EG 5. sterilization by exposure by exposure by exposure by exposure by exposure to steam autoclaving ethylene oxide ultraviolet light Laser Gamma radiation

Representative surfaces from these sterilization groups will be examined using a series of surface analytical techniques including scanning electron microscopy (SEM),

‫‪X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and‬‬ ‫‪contact angle measurements. Cell attachment assays using murine fibroblasts will be‬‬ ‫‪performed on titanium surfaces from each sterilization group and on tissue culture‬‬ ‫‪plastic controls. Mean percent cell attachment values for each group will be obtained‬‬ ‫‪for periods of up to 1 hour. The data will be collected and analysed‬‬

‫ٍيخص ببىيغت اىؼشبٞت :‬ ‫تؼتَذ ػَيٞت اىتئبً ػظبً اىفل ح٘ه غشسبث األسْبُ بذسخت مبٞشة ػيٚ اىخصبئص‬ ‫اىسطحٞت ىغشسبث اىَستخذٍت0 ٗ بَب اُ ػَيٞت اىتؼقٌٞ ٕٜ آخش ٍشحيت ٍِ ٍشاحو اىتصْٞغ‬ ‫ه‬ ‫ىيغشسبث اىتٚ تستخذً فٜ اىفنِٞ فٖزٓ ٍشحيت ٍَٖت ىيتأثٞش اىٌببشش ػيٚ أسطح‬ ‫اىغشسبث0 ٗػيٚ رىل فْٖبك سؤاه ٌٍٖ إىٚ أٛ ٍذٙ تؤثش ػَيٞت اىتؼقٌٞ ػيٚ أسطح اىغشسبث ؟‬ ‫ٗأٝضب أٛ ّ٘ع ٍِ تقْٞبث اىتؼقٌٞ اىحذٝثت ىٔ تأثٞش سيبٜ أمثش ٍِ األخش ػيٚ أسطح اىغشسبث؟‬ ‫ٗببإل خببت ػيٚ ٕزٓ األسئيت ّستطٞغ أُ ّستخذً أفضو ٕزٓ اىتقْٞبث ٍالئَت إلّتبج أسطح قببئ‬ ‫ىَْ٘ اىؼظبً ػيٖٞب بطشٝقت سيَٞت. ٗػيٚ رىل سٞتٌ إخشاء ٕزا اىبحث بتأثٞش تقْٞبث حذٝثت ىيتؼقٌٞ‬ ‫ػيٚ أسطح غشسبث األسْبُ .‬ ‫ٗس٘ف تقسٌ اىغشسبث إىٚ خَس ٍدَ٘ػبث ٗٝتٌ تؼقٌٞ مو ٍدَ٘ػت بْ٘ع ٍختيف ٍِ اىطشق‬ ‫اىحذٝثت ىيتؼقٌٞ ٗس٘ف ٝتٌ فحص اىْتبئح ببستخداً أخٖزة ٍتط٘سة ٗتقْٞبث حذٝثت ىَقبسّت‬ ‫أسطح اىغشسبث بؼذ اىتؼقٌٞ ٗ ُحيو اىْتبئح إحصبئًٞ.‬ ‫ب‬ ‫ت‬


								
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