Cumhuriyet Dental Journal 5g_Zgd[kWf 6W`fS^ <agd`S^ Volume 17 Issue 3 doi:10.7126/cdj.58140.5000016784 9ROXPH1XPEHU H,661 available at http://dergipark.ulakbim.gov.tr/cumudj/ 2IILFLDO3XEOLFDWLRQRI&XPKXUL\HW8QLYHUVLW\)DFXOW\RI'HQWLVWU\ RESEARCH ArticLE The effects of disinfectant solutions on the viscoelastic properties of acrylic resins Perihan Oyar, DDS, PhD,a Gulsen Can, DDS, PhDb aDental Prosthetics Technology, School of Health Service, Hacettepe University, Ankara, Turkey bDepartment of Prosthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey ARTICLE INFO ABSTRACT Article history: Objectives: The aim of this paper was to analysis the effects of disinfectant solutions on Received 09 May 2014 polyoxymethylene viscoelastic properties in comparison with polymethyl methacrylate. Accepted 25 June 2014 Materials and Methods: Polymethyl methacrylate and polyoxymethylene acrylic and 200 mL 5% chlorhexidine gluconate, 2% sodium hypochlorite and one Corega Tabs dissolved in 200 mL water at 40°C were used. The storage modulus, loss modulus, Tanδ and glass transition temperatures of the disinfected acrylic resins were observed with the Thermal Dynamic Keywords: Acrylic resins Mechanical Analyzer. Disinfectant solutions Results: Lower storage modulus values were observed in the disinfectant solutions at Dynamic mechanical thermal analysis polymethyl methacrylate specimens. The storage modulus showed lower values than the Viscoelastic properties control group at chlorhexidine gluconate, higher values at sodium hypochlorite in the disinfectant solutions at polyoxymethylene specimens. While the glass transition temperatures of polymethyl methacrylate in the disinfectant solutions showed proximal values, the glass transition temperatures of polyoxymethylene in the chlorhexidine gluconate showed lower temperatures (approximately 11%). Conclusions: The storage modulus, loss modulus, Tanδ values of polyoxymethylene were lower than those of Polymethyl methacrylate. The Corega Tabs did not affect the viscoelastic properties of polyoxymethylene. Chlorhexidine gluconate and sodium hypochlorite did not affect the viscoelastic properties of polymethyl methacrylate. INTRODUCTION originating from free acetal resin monomers.1 Acetal resin is a polycrystalline structure and an Ethylene-derived thermoplastic acetal resins 2 have recently come into use as alternatives injection-molded resin. Acetal resin has been to metal substructures for removable shown to have good physical and mechanical partial dentures. These resins are a type properties. The material has been also shown of polyoxymethylene (POM) that have a to have good biocompatibility that’s why branchless, linear chain structure formed it was considered as a framework material by the polymerization of formaldehyde for removable partial dentures for patients Corresponding author at: Peihan OYAR, Dental Prosthetics Technology, School of Health Service, Hacettepe University, 06100 Sıhhıye, Ankara, Turkey. Tel.: +90-312-305 15 87/111, Fax.: +90-312-3102730. E-mail: [email protected] 205 Oyar and Can: The effect of disinfectant solutions on acrylic resins with allergic reactions to metal alloys. to cause undesirable changes in the These properties make it an appropriate physical properties of the acrylic base.17-19 material for removable partial dentures, Depending on the type and length of complete dentures, provisional bridges, contact, disinfection agents may cause occlusal splints, orthodontic and sleep structural changes in the inner matrix apnea appliances.3-6 Prolonged use requires of the polymer.20,21 Chau et al.22 reported that these materials exhibit chemical and that 1% sodium hypochlorite eliminated mechanical resistance in their surrounding microorganisms from the denture, and environments over time. Numerous factors another study found immersion in affect the mechanical properties of resins, 1% sodium hypochlorite, 4% chlorhexidine including polymer molecular weight; ratio gluconate, or 3.78% sodium perborate for of residual monomers, plasticizers and 10 minutes produced no change in the cross-linking agents; internal porosity of transverse strength of heat-polymerized the polymer matrix; material thickness; polymethyl methacrylate. Similarly, finishing techniques; contact with chemical Angelillo et al.23 stated that glutaraldehyde- agents; and patient-related factors. Resin based disinfectants provided effective properties may also be affected by loss of disinfection without causing degradation soluble components or water sorption, in plastic and rubber materials. Ayaz tension and temperature changes related et al.24 al stated that the effervescent to hot and cold food intake during clinical denture cleaners (sodium perborate, use.7-10 sodium bicarbonate) may be degradation in polymer structure of acrylic resins and The porous structure of acrylic resin change color of acrylic resin teeth. as well as the presence of any surface scratches or pits allow microorganisms In contrast, other studies have reported to easily attach themselves to an acrylic- changes in the flexural strength of resin resin denture. Thus, in addition to long- immersed in sodium hypochlorite and, term contact with oral tissue, saliva, with heat application, alkaline peroxide.17,25 blood and water in the oral environment, Shenet et al.20 reported softening of resin an acrylic-resin denture also requires surfaces exposed to glutaraldehyde alkaline immersion in a cleaning solution for long disinfection with phenolic buffer for periods of time. Disinfection is necessary 2 hours, with the affect increasing with in order to minimize cross-contamination further exposure, and Peracini et al.18 found between the patient, dental personnel that Corega Tabs caused a considerable and the denture.11-13 McCabe et al.14 reduction in the flexural strength of acrylic stress the need for proper disinfection resin as well as a color change. of all prostheses. This may be achieved DMA is a method used to analyze the using various chemicals, including viscoelastic properties of polymeric materials glutaraldehyde, chlorhexidine gluconate, through the application and measurement alkaline peroxides, alkaline hypochlorites, of controlled sinusoidal stress.26-29 The null diluted acids and enzymes.15 In addition, hypothesis was that different disinfectant Gronitskey et al.16 have suggested that solutions would affect the viscoelastic sodium perborate products (Corega Tabs) properties of POM and polymethyl may have an antimicrobial effect. methacrylate acrylic resin (PMMA). In order The disinfection process is expected to better understand the effects of hygienic to have no negative effect on denture procedures on the viscoelastic properties of materials; however, a number of studies acrylic resin prosthetics, this study analyzed have reported some disinfectant solutions and compared the effects of 3 different 206 Oyar and Can: The effect of disinfectant solutions on acrylic resins disinfectant solutions on the viscoelastic N2 atmosphere and temperatures ranging properties of POM and PMMA acrylic resin from -60 to +250°C with heating rate of using DMA. 10°C/min. (POM specimens could not be observed above +160°C because of the melting point of the material). MATERIALS AND METHODS DMA measurements are sensitive Two different types of acrylic resin to micro-level structural changes and [PMMA(QC-20 resin; De trey, Dentsplay, are capable of thoroughly analysing the England) and POM (Dental D;Quatrotti, viscoelastic behaviour of polymers with RovelloPoro, Italy)] and 3 different types of relatively few samples. Because of the disinfectants [5% chlorhexidine gluconate small number of samples in the present (Dental D, Quatrotti, RovelloPoro, Italy); study, a detailed statistical analysis was not 2% sodium hypochlorite (Miyako do Brazil performed. Similar recent studies of the Id e Com; Guarrulhos, Brazil); CoregaTabs viscoelastic properties of dental materials (Stafford Miller; Dungarvan Co, Waterford, have also been conducted without Ireland)] were used in this study. performing statistical analysis.30-34 Acrylic specimens (20 mm × 10 mm × 4 mm) were prepared according to the RESULTS manufacturers’ instructions and divided into the following groups: E’ values are shown in Figure 1-3. Among Aa (n=1) : PMMA/chlorhexidine gluconate PMMA specimens, E’ values of specimens Ab (n=1) : PMMA/sodium hypochlorite immersed in chlorhexidine gluconate (Aa) Ac (n=1) : PMMA/Corega Tabs (Fig. 1) were similar to those of the control Ba (n=1) : POM/chlorhexidine gluconate group (Ad), whereas E’ values of specimens Bb (n=1) : POM/sodium hypochlorite immersed in sodium hypochlorite (Ab) Bc (n=1) : POM/Corega Tabs (Fig. 2) and in Corega Tabs (Ac) (Fig. 3) were Ad (n=1) : PMMA/200 mL distilled water lower than those of the control group. Among (control) POM specimens, E’ values of specimens Bd (n=1) : POM/200 mL distilled water immersed in chlorhexidine gluconate (Ba) (control) (Fig. 1) were lower than those of the control group (Bd), whereas E’ values of specimens Disinfectants were dissolved in 200 mL immersed in sodium hypochlorite (Bb) distilled water at 40°C and thermocycled (Fig. 2) were higher than those of the control (MSCT-3 plus; Marcelo Nucci-ME, Sao group and E’ values of specimens immersed Carlos, Brazil) at 5°-55°C with a 60-second in Corega Tabs (Bc)(Fig. 3) were similar to dwell time. Each specimen was immersed those of the control group.z for 10 minutes in one of the solutions, removed and rinsed for 2 minutes in E’’ values are shown