Influence of dental cleansers on the color stability and surface roughness of three types of denture bases

Transcription

1 Influence of dental cleansers on the color stability and surface roughness of three types of denture bases Hussam M aied B.D., M.c. (1) ABTRACT Background: This study is concerned with color stability and surface roughness of three types of denture base materials when immersed into three types of denture cleansers. Materials & method: Forty five specimens were prepared, fifteen of each type were immersed into distilled water for 48hours which regarded as control and then each five specimens were immersed into one of three different denture cleansers for twelve hours then undergone testing for color stability and surface roughness,the results were analyzed by paired t-test and ANOVA test. Results: In color stability the hot cure acrylic give non significant difference p>0.05 with denture cleansers, the soft base give (H) high significant difference which is greatly affected by denture cleansers while the nylon denture was significantly affected by bleach rather than the other two cleansers was non significant. The ANOVA test show smooth effect of fitty dent (N)on both nylon and soft base. The surface roughness test it was significantly affected by denture cleansers by t-test while ANOVA the smooth effect of both fitty and lacalut dent on denture bases with non significant difference. Conclusion: Denture cleansers can cause whitening or color fainting or even bleaching. The surface texture affected by cleansers in deferent level according to time of immersion, concentration and type of active component that lead to increase of roughness or wear of denture outer surface. The effect of fitty dent was safer in its action and smoother than bleach and lacalut. Key words: Denture base, dental cleaners, surface roughness. (J Bagh Coll Dentistry 2011;23(3): 17-22). INTRODUCTION Almost all complete dentures are fabricated by using an acrylic resin, low cost material that requires relatively ease manipulation and construction methods. How ever its not the ideal material in every aspects. Discoloration of acrylic resin results in esthetic problems and the denture base polymers should have a good esthetic and smooth glassy surface and should be capable of matching the natural appearance of the soft tissue (1) Color and translucency should be maintained during processing and the resin should not be stained or change color during clinical use. Color stability is an important factor for many dental materials. (2) These dentures should be accurate and fit inside patient mouth which is an important rule. (3) How ever the process of alveolar resorption is irreversible and may lead to in adequate fit of the prosthesis (4), the use of resilient lining materials is useful in removable prosthdontics because of their capability of restoring health to inflame ed mucosa (5,6), leading to more equal distribution of functional load on the denture functional area (7,8) (1) Assistant lecturer/prosthodotic department collage of dentistry/baghdad University In recent years,nylon polymer has been attracting attention as a denture base material because of multiple advantages like favorable esthetic outcome, toxological safety to patient allergic to conventional metals and resin monomers (9,10), higher elasticity than conventional heat polymerized resins and sufficient strength for use as a denture base material (11) As well as the use of heat modeling instead of chemical polymerization to ease conventional challenges such as deformation during the polymerization process and the presence of non polymerized residual monomer (12,13) Due to exposure of these denture bases to different food and drink colorants that lead to denture staining, these color changes give the demand for the denture cleansers which are commercially available with different types (14,15) Denture cleansers remove the outer staining and widely used to prevent plaque formation and bacterial colonization (14) However, denture cleansers can cause significant deterioration because they can cause loss of soluble components and plasticizers and/or absorption of water and other salivary component by the resilient denture base material that lead to more surface roughness and color change (17,18) The purpose of this study is to determine the influence of denture cleansers on the color stability of three different types of denture base materials. Restorative Dentistry 17

2 MATERIAL AND METHOD Three types of denture base materials were chosen to be tested in this study which are mostly used now a days for denture construction which are hard hot cure acrylic (Major Dent, Italy), hot cure soft base silicon (Vertex, Nethrlands) and Nylon or flexite supreme denture base rapid injection system (Menniola NY) (19). These are selected to evaluate the effect of deferent denture cleansers o n color stability and surface roughness of denture bases made from them. The denture cleansers that has been used in this study were three types with different ingredients one of them was commercially available and (Bleach), while the two other types supplied as tablets give their effect when socked into water (denture cleansing tablets) as shown in the table 1. Fifteen specimens for each material were constructed as a disc of 50mm in diameter & 1mm thickness according to ADA specification (20). These are firstly constructed by using flexible nylon sheet that was prepared for inter occlusal appliance for teeth whitening by biostar which had thickness of 1mm,these were cut as discs of 50mm diameter,then poured into metal flask one disc for each flask,when stone was completely set,the flexible disc was removed by sharp clamp, then after that separating media was applied. Both the hard and soft base acrylic were packed and processed according to manufacture procedure manual. While the nylon was under gone heating and injection by special thermal press device to construct the final discs.these specimens were smoothed and polished by Lathe cut polishing machine. all specimens were washed and kept into distilled water for 48 hours at 37C for several days and then under gone testing. Evaluation of surface roughness A five specimens were selected randomly to be undergone the surface roughness test as a control before the cleansers application. The surface roughness test was done by measuring the average surface roughness (Ra) using Analyzing surface roughness tester (TR220 portable roughness tester, Beijing, Time high technology. Ltd, China) device. According to managing protocol the tester take a distance 8mm on the surface of the tested material which crossed by sensible needle,this area of examination was selected and marked by the operator which should be smooth and encircled in away to check the same area before and after cleansers application (21,22) Color evaluation Color measurements were done for each specimen by using an ultra violet visible light recording spectrophotometer model UV-160A, himadzu,kyoto,japan) wave length nm (23,24) Denture cleansers application Five specimens of each material were immersed in each denture cleansers for 12 hours at 25 C, washed thoroughly with tab water and then immersed in distilled water for 12 hours at 37 C, then applied these specimens were subjected for color change measurements (25) REULT AND DICUION The null hypothesis that there would be no effect of denture cleansers on the color stability of denture base acrylic resin was rejected. However the influence of denture cleansers on the color stability of denture base material was different according to difference in the types of these bases & cleansers active components Longevity of denture base materials is significant problem in prosthodontics. The color stability of a prosthesis may be the most important factor for determining the patient acceptance (26-28) The color changes of all acrylic resins increases as immersion time increases,it has been reported that denture cleansers can cause whitening or color fainting or even bleaching, loss of soluble components, water absorption in acrylic resin materials this is in agreement with arac D 2007 and Purnaveja 1982 (28,29) The mean values obtained were different from each other according to difference in denture base materials, the higher the value,the more is the consistency of the material with less translucency of it, so it will absorb more light before it can pass through it. For the hot cure acrylic when immersed into denture cleansers,the mean value was not greatly affected which documented by t-test that there was (N) no significant difference p 0.05 with control group and this was explained by the great Restorative Dentistry 18

3 resistance of the resin material due to high cross linking between the poly methyl meth acrylate. The soft base liner is more affected by the bleaching with () significant difference p 0.05 with control & this occur due to effectiveness of sodium hypochlorite by dissolving the organic plasticizers,while both Fitty & Lacalut dent give (H) highly significant difference p 0.01 due to the acidic ingredients of these cleanser which were highly affecting of dissolving the plasticizers. While the nylon flex is slightly affected by the bleaching which give significant difference in the test, otherwise both Fitty & Lacalut dent although their acidic bases but they give no effect on it, so (N) no significant difference were detected, the nylon flex is more compact & its co polymer can be more resistance to dissolve or react with acidic materials. F-test describe the effect of the three materials, the action of bleaching give highly significant difference (H) p 0.01 due to great difference in the chemical composition of them& less cross linking between molecules. The poly methyl methacrylate denture base resin were hydrophilic that attract more water soluble materials on the surface that absorption is undoubtedly due primarily to the polar properties of resin molecules. However, it has been proven that the mechanism is diffusion of water molecules that penetrate according to diffusion law, but still the high bond due to cross linking agent give its resistance (24) In table (3) which describe the surface roughness tests, from the mean values & t-test that reveled there were a() p 0.05 in the effect of the whole cleansers in comparison with control group.the hot cure acrylic had a dropping in the mean values after immersing in cleansers which mean that the surface will be smoother & this explain why see a smear layer on the specimen surface which had been undergone slight dissolving of the surface particles,longitudinally this effect was not accepted because the material wear by time which affect on the functional properties of the denture, these observation come (14,15) in agreement with Nikawa et al. who observed that the high peroxide content and level of oxygenation in the strongly alkaline solution is a damaging factor for the denture base materials. ome authors reported that some denture cleansers can cause a loss of soluble components or absorption of water or saliva by denture base material (28,29) Peroxide denture cleansers include an effervescent component such as sodium perborate or sodium bicarbonate, when these tablets dissolve in water, sodium perborate decomposes to form an alkaline peroxide solution. This peroxide solution subsequently release oxygen and loosen debris by mechanical means (14,28) Therefore use of these denture cleansers may cause hydrolysis and decomposition of the polymerized acrylic resin itself, this observation may explain why these cleansers had a greater influence on color stability of denture base. The soft base liner with bleach had increase in the mean values after bleaching with the increase of roughness and this may be related to dissolving of some large molecules & plasticizers,although there was an increase in the surface roughness but statistically has on benefit which give (N).otherwise both fitty & lacalut dent by t-test had () in which the effect of the materials will drop the mean value make it with slight smoother surface,also the same effect found on nylon flex in a () difference by the cleansers action when compared with control group immersed in distilled water. ANOVA describe the effect of these cleansers on different denture base materials, both bleach and fitty dent had (H) difference in their effect on these denture bases, while the lacalut has mild effect which give (). By the LD test both bleach & fitty dent has (H) in their effect on the hot cure & soft base liner while the lacalut give ().as well as the same results of these cleansers when compared the hot cure & nylon flex,this may be explained by the difference in the chemical composition & physical properties between the denture base materials. While for both soft base liner &nylon flex has a() difference find by the effect of bleach, but this was not find by the effect of both fitty & lacalut dent which smoother effect on the surface on the above denture base, so (N) were obtained REFERENCE 1. hotwell JL,Razzog ME, Koran A. Color stability of long term soft denture liners. J Prosthet Dent 1992; 68: Lee YK, Lim B, Kim CW. 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4 lining materials to denture resin. Dent Mater 1999;15: inobad D, Murphy NM, Huggett R, Brook. Bond strength & rupture properties of some soft denture liners. J Oral Rehabilitation 1992;19: Hargreaves A. Nylon as a denture base material. Dent pract,dent res 1971;22: Yunu N, Rashid AA, Azmil L, Abu Hasan MI. ome flexural properties of a nylon denture base polymer. J Oral Rehabilitation 2005;32: Katumata Y, Hojo, Ino, Hamana N, Watanab T, uzuki y, Ikeya H, Morino T, Toyoda M. Mechanical characterization of flexible nylon denture base material.bull Kenagawa Dent Col 2007;35: Degochi R, Polymide 6. Japan plastics 199-;41: Hart H, Carien LE, Hart DJ. Tithe 10 th ed,baifukan Co,Tokyo2006;pp: Nikawa H, Hamada T, Ymashiro T, Kumagai H. A review of in vitro &in vivo methods to evaluate the efficacy of denture cleansers 1999;12: Nikawa H, Iwang H, Hamada T, Yuhta. Effect of denture cleansers on direct soft denture lining material.1994;72: Nikawa H, Hmada T, Ymamoto T. Effect of salivary or serum pellicles on the candida albicanse growth & bio film formation in soft lining materials in vitro.j Oral Rehabil 1997;24: Braden M, Wrights P. Water absorption & water solubility of the soft lining material for acrylic denture J Dent Res 1983;62: Joes DW, Hull GC, utow EJ, Langman MF, Robertson KN. Chemical & molecular weight analysis of prosthodontic soft polymers. J Dent Res 1991;70: Vedenbrink JP, Wolfaardt JF, Fullkner MG. A comparison of various removable partial denture clasp materials & fabrication procedure for placing clasps on canine & premolar teeth. J Prosthet.Dent 1993;70: American national standard, American Dental Association specification No12 April 23, Evandro A artori, Caroline B hmidt, Rosmary Arashinkai. Effect of microwave disinfection on denture base adaptation & resin surface roughness. Braz Dent J 2006;17(3): Ana Lucia Macado, Carlos E, Vergani, Lusiano E.Perez. Hardness & surface roughness of eline and denture base acrylic resin after repeated disinfection procedure. J Prosthet Dent 2009; 102: Yu-Lin-Lai, Ho-Fu-Lui, hyn-yuan. In vitro color stability stain resistance & water sorption of removable gingival flange materials. J Prosthet Dent 2003;90: Nur Hersik, enay Canany, Gulay Uzun. Faith Yaldis. Color stability of denture base acrylic resins in three food colorants. J Prosthet Dent 1999; 81: Guang Hory, Hiroshi Morata, Yiney AiLi, Taizo Hamada. Influence of denture cleansers on color stability of three types o denture base resin. J Prosthet Dent 2009;101: Polyzois GL, Yanni Kakis A, Zissis AJ. Color change of denture base material after disinfection and sterilization immersion. Int J Prosthod 1997;68: Anil N, Hekimoglu C, ahin. Color stability of heat polymerized and auto polymerized soft denture liners. J Prosthet Dent 1999;81: arac D, arac Y, Kurk M. The effectiveness of denture cleansers on soft denture liners colored by food colorants solution. J Prosthet Dent 2007;16: Puveja, Fletcher AM, Ritchie GM, Amin WM. Color stability of two self cure denture base materials. Biomaterials 1982;3: Table 2: Mean and D of Color stability tests before and after cleanser application control bleach Fitty dent Lacalut dent Hot cure acrylic Mean D oft base lining Mean D Nylon flex Mean D t-test between before with Bleach, Fitty dent, Lacalut dent bleach Fitty dent Lacalut dent t-test P-value t-test P-value t-test P-value Hot cure acrylic ,952 N N N oft base lining H H Nylon flex N N *P<0.05 ignificant **P>0.05 Non significant *** High significant Restorative Dentistry 20

5 ANOVA between groups F-test P-value Bleach H Fitty dent H Lacalut dent H *** High significant LD bleach Hot cure acrylic & oft base lining P-value ig H Hot cure acrylic & Nylon flex P-value ig H oft base lining &Nylon flex P-value ig * P<0.05 ignificant ** High Fitty dent H N Lacalut dent H H Table 3: Mean and D of urface roughness tests before and after cleansers control bleach Fitty dent Lacalut dent Hot cure acrylic Mean D oft base lining Mean D Nylon flex Mean D t-test between before with after, Fitty dent, Lacalut dent Hot cure acrylic oft base lining Nylon flex bleach t-test P-value N Fitty dent t-test P-value *P<0.05 ignificant **P>0.05 Non significant ANOVA between groups F-test P-value bleach H Fitty dent H Lacalut dent *P<0.05 ignificant ** High significant Lacalut dent t-test P-value Restorative Dentistry 21

6 LD bleach Fitty dent Lacalut dent P-value Hot cure acrylic & oft base lining ig H H Hot cure acrylic & Nylon flex P-value ig H H P-value oft base lining &Nylon flex ig N N *P<0.05 ignificant **P>0.05 Non significant Restorative Dentistry 22