Basima F.doc J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 15 Effect of addition ZrO2-Al2O3 nanoparticles mixture on some properties and denture base adaptation of heat cured acrylic resin denture base material Ali MA Aljafery, B.D.S. (1) Basima MAH, B.D.S., M.Sc., Ph.D. (2) ABSTRACT Background: The PMMA polymer denture base materials are low mechanical properties, adaptation of the denture base to underlying tissue is important for retention and stability of denture. The aim of the study was toevaluate the effect of mixtureZrO2-Al2O3 nanoparticles on impact strength, transverse strength, hardness, roughness, denture base adaptation of heat cured acrylic resin denture base material. Materials and methods: One hundred (100) specimens were prepared, the specimens were divided into five groups (20 specimens to each) according to the test type, each group was subdivided in to two subgroups (control and experimental) each subgroup consist of 10 specimens, the experimental group included mixture of 2% (ZrO2- Al2O3ratio2:1) by weight. Theimpact strength was measured by Charpy's impact testing machine, the transverse strength was measured by Instron testing machine while the hardness was measured byshore D durometer and roughness was measured by Profilometer. Denture base adaptation was measured by digital microscope and evaluated by computerized tomography (CT). Results: Highly significant increaseofimpact and transverse strength, non-significant increase ofhardness, significant increase ofroughness andreduction of denture base adaptation (measured at 3 point A, B and C) occurred in experimental groupwhen compared to control group. CT evaluation, gap between the denture base and master cast (control and experimental groups) increased from the anterior to posterior side of palate and from the alveolar ridge to the mid palatal line. Conclusion: The polymer nanocomposites had mechanical properties higher than neat PMMA at same time less denture base adaptation. Keywords: Acrylic denture base, nano fillers, mechanical properties, denture base adaptation. (J Bagh Coll Dentistry 2015; 27(3):15-21). INTRODUCTION Acrylic resin polymethyl methacrylate (PMMA) is the most extensively used material in fabrication of dentures. Although it is very popular, this material is still insufficient in fulfilling the ideal mechanical requirements of such appliances (1). Clinicians still encounter fracture of this material due to low resistance to impact, flexural, or fatigue stresses (2). In order to prevent fracture of the dentures, the thickness of acrylic resin in susceptible regions, such as the palatal midline, and the mandibular lingual and labial frenal attachments has been increased(3). In addition, improvement on mechanical properties of denture base materials were tried to be achieved either by adding a polyfunctional cross-linking agent such as polyethylene glycol dimethacrylate (4) or by incorporating a rubber phase (5), metal oxides, metal wire (6,7) or fiber (8). The reinforcement of polymers used in dentistry with metal-composite systems has been a prime interest. Addition various amounts of powdered Cu, Ag and Al into the PMMA resin and reported increased compressive strength but decreased tensile strength (9). (1)M.Sc. Student. Department of Prosthodontics, College of Dentistry, University of Baghdad. (2)Assistant Professor. Department of Prosthodontics, College of Dentistry, University of Baghdad. Evaluation the changes in the mechanical properties of PMMA, polyethyl methacrylate (PEMA) and poly isobutyl methacrylate (PIMA) resin matrices by reinforcingwith oxides of Al, Mg, Zr and pulverized E-glass particles (10). They suggested that 2% admixtures by volume in PMMA resin matrix resulted in better mechanical properties. Much attention has been directed toward the incorporation inorganic nanoparticles in to PMMA to improve its properties. The properties of polymer nanocomposites depend on the type of incorporating nanoparticles, their size and shape, as well as the concentration and interaction with the polymer matrix (11). Nanoparticles were undergone surface treatment with silane coupling agent and embedded in to PMMA (12). Alumina nanoparticles were treated with trimethoxysilylpropylmethacrylate (TMSPM) to get PMMA/alumina Nano composite with improved properties over pure PMMA (13). Also, using modified ZrO2 with trimethoxysily- lpropylmethacrylate to get PMMA/ ZrO2 Nano composite to improve properties of PMMA (14). Furthermore, studying an experimental investigation of mixture HA/AL2O3 nanoparticles on mechanical properties of restoration materials (15). Also, evaluation of influence of mixture of ZrO2-TiO2 on mechanical and physical properties J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 16 of heat-cured polymethyl methacrylate denture base resins (16).Though the incorporation of fillers like rubber and fibers to heat-cured poly methyl methacrylate resin improves the impact strength and fatigue resistance, it may affect some of the properties of heat-cured poly methyl methacrylate resin such as fitness accuracy (denture adaptation), dimensional stability and the effect of water sorption (17). Various investigators have compared the dimensional changes between different denture base materials (17,18), palatal vault configurations (19), methods of packing (18), modes of polymerization (20) and curing cycles (21). This study was conducted to use inorganic mixture of ZrO2-Al2O3 Nano fillers that were added to heat cure PMMA and test the effect of this addition on the some mechanical properties and denture base adaptation of heat cured acrylic denture base material. MATERIALS AND METHODS Some of the materials used in this study are summarized in table (1). Table 1: List of the materials that were used Material ZrO2 nanofiller Al2O3 nanofiller Trimethoxysilylpropyl methacrylate(TMSPM) Heat-curing acrylic resin Manufacturer HWNANO China NS6130 01-123 Germany 2530-85-8 Germany Vertex Netherlands Test specimens preparation Two different plastic patterns were constructed according to the required test. The pattern that was constructed for impact strength a bar shaped specimen (80mm X 10mm X 4mm) length, width, thickness respectively (22). For transverse strength test: a bar shaped specimen was constructed (65mm X 10mm X 2.5mm) length, width, thickness respectively (23) (Figure 1). Same specimen measurement was used to prepare hardness test and roughness test. For denture base adaptation test: prepare acrylic resin denture bases with their corresponding master casts byconventional denture flasking technique using a Biostar sheet as record base (2mm thickness) without teeth. Figure 1: Plastic patterns; A for transverse strength, B for impact strength Surface modification of nanofillers (ZrO2, Al2O3) The introduction of reactive groups to the fillers surface was achieved by reaction of 3- trimethoxy silylpropyl methacrylate (TMSPM) with zirconium oxide and aluminum oxide Nano fillersthrough salinization procedure (24). For ZrO2, TMSPM was used in 5% wt. of nanofiller, toluene was used as a solvent to ZrO2 (12,14,24), while Al2O3,TMSPM was used in 75% wt. of Al2O3, ethanol was used as a solvent toAl2O3 (13). Mould preparation Addition of fillers This only for experimental groupincluded mixture of 2% (ZrO2-Al2O3 ratio 2:1) by weight, electronic balance (Sartorius, Germany)with sensitivity of (0.0001g)was used to weigh then nanofillers powder weight in 2%wt. of the PMMA powder weight. The filler was added to the monomer of PMMA mixed by the probe sonifier apparatus (DANBURY, U.S.A.) for 3 minutes (13,14) to disperse the nanoparticles in the monomerand reduce the possibility of particle aggregation. Mixing of the acrylic Acrylic materialwas mixed and manipulated according to manufacturer's instructions using a conventional water bath denture flasking technique for both groups (control and experimental). For experimental group the suspension of the monomer with nanofiller was immediately mixed with acrylic powder. Mechanical and denture base adaptation tests 1-Impact strength test. a- All theprepared specimens (20 specimens, 10 for each control and experimental groups) stored in distilled water inside incubator at 37°C for 48 hours before testing (23). b- Testing procedure: The impact strength test was carried out following the procedure recommended by the ISO 179 usingimpact testing device (Tmi, testing machine Inc. Amity Ville, New York, USA) (22) (Figure 2).The specimen was supported horizontally at each end and strucked by free swinging pendulum of 2 Joules. A B J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 17 The scale readings give the impact energy in Joules. The charpy impact strength of un-notched specimen was calculated in Kilo-joules per square meter using the following formula: Impact strength (kj/m2) 103 where E: The impact energy in Joules, b: Is the width of the specimens in millimeters, d: Is the depth of the specimens in millimeters. 2-Transverse strength test. a. All the prepared specimens (20 specimens, 10 for each control and experimental groups) stored in distilled water inside incubator at 37°C for 48 hours before being tested (23). b. Testing procedure: The test was performed using Instron universal testing machine (WDW- 200 E, UK) (Figure 3), each specimen was positioned on the bending fixture which consist of two parallel supports (50 mm apart). The load was applied by a rod placed centrally between the supports with across head speed of 1mm/min applied making deflection until fracture occurs. The transverse strength was calculated using the following formula: Transverse strength (N/mm2) Where P: is the peak load, L: is the span length, b: is the sample width, d: is the sample thickness (25). Figure 2: Impact strength testing device Figure 3: Instron testing device 3- Measuring hardness property a- All the prepared specimens (20 specimens, 10 for each control and experimental groups) stored in distilled water inside incubator at 37°C for 48 hours before being tested (23). b- Testing procedure: Test was performed using durometer hardness tester (shore D hardness, TH210, Italy)which is suitable for acrylic material (23). The instrument consists of a blunt pointed indenter (0.8 mm in diameter) that present in a cylinder (1.6mm in diameter) .The indenter was attached to a digital scale that is graduated from 0 to 100 unit. The usual method was to press down firmlyand quickly on the indenter, a measurements were taken directly from the digital scale reading. Five measurementswere recorded on different areas of each specimen and an average of these five readings was recorded. 4-Measuring surface roughness. a- All the prepared specimens (20 specimens, 10 for each control and experimental groups) stored in distilled water inside incubator at 37°C for 48 hours before being tested (23). b- Testing procedure: The Profilometer device surface roughness tester (TH 210, China) was used to test the micro geometryof the surface for experimental and control group.The device has surface analyzer (sharp stylus made from diamond) to trace the profile of the surface irregularities. It moves for maximum distance of 11 mm. The Profilometer records by its scale all the peaks and recesses which characterized the surface of the specimen under testing. The analyzer pass along the specimen surface for 11 mm distance. Three locations were selected in every specimen making 3 readings then the mean of these readings were recorded as a surface roughness value for each specimen. 5- Denture base adaptation testing a- Microscopic measurement:The cast- denture base sets (20 specimens, 10 for each control and experimental groups)was sectionedto a horizontal line 5 mm away from theposterior end of the cast using a cutting saw device under water cooling (26,27). Three points were marked on the cast on transverse line at the posterior border of the cast specimens (deepest point of the left vestibule, left ridge crest andmidline point which is marked according to the line bisecting the incisive papilla and extending posterior on the cast) as (A, B and C) respectively (figure 4) (26). Figure 4: Denture base with its castshow position of 3 points: (1) point A, (2) point B and (3) point C 2 1 3 J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 18 The gap between the cast and the denture base margin at these 3 points was measured with the use of digital microscope (Dino- Lite, Taiwan) of magnification 200x capability and accuracy of 0.001 mm. Two measurements were made, first one made immediately after deflasking and sectioning for all the samples. Second measurement was done after incubation in distilled water at 37°C for 14 daysfor all the samples (27), then each denture base was seated on its corresponding cast and measurement of the gab was done while a weight of 1kg was placed over the denture base to ensure a proper seating of the denture base over the cast (26). b- To observe the overall gap formation of the denture base, All denture bases placed on theirrespective master cast for each group was scanned by computerized tomography(Light Speed, Philips, Netherland), (figure 5). The frontally-sectioned images of the denture-cast set and sagittal images obtained at the palatal midline were taken from the CT data (27). A B Figure 5: A- computerized tomography device, B- The casts with their corresponding denture bases under scanning RESULTS Mean values, standard deviation, t-test, p- value and Significances of mechanical properties presented in table (2). Table 2: Descriptive and statistics of mechanical properties Property Tested groups N Mean S.D. T-test P. value Sig. Impact strength (Kj/m2) Control group 10 7.94 0.25 -16.02 0.000 HS Experimental group 10 9.63 0.22 Transverse strength (N/mm2) Control group 10 88.50 0.77 -11.85 0.000 HS Experimental group 10 93.48 1.08 Surface hardness Control group 10 84.64 1.12 -1.316 0.205 NS Experimental group 10 85.35 1.27 Surface roughness (μm) Control group 10 1.29 0.08 -2.309 0.033 S Experimental group 10 1.37 0.07 Mean values, standard deviation, t-test, p-value and Significances of the gap at three selected points (A, B and C) to measure denture base adaptation presented in table (3). Table 2: Descriptive and statistics of the gap(mm)at three point point Time Tested groups N Mean S.D. T-test P-value Sig. Point A Immediately After deflsking Control group 10 0.122 0.018 -2.160 0.045 S Experimental group 10 0.160 0.054 After incubation 14 day Control group 10 0.143 0.038 -2.266 0.036 S Experimental group 10 0.195 0.063 Point B Immediately After deflsking Control group 10 0.065 0.016 -2.61 0.018 S Experimental group 10 0.081 0.013 After incubation 14 day Control group 10 0.088 0.035 -1.64 0.111 NS Experimental group 10 0.113 0.036 Point C Immediately After deflsking Control group 10 0.244 0.040 -0.711 0.486 NS Experimental group 10 0.257 0.033 After incubation 14 day Control group 10 0.284 0.053 -0.524 0.607 NS Experimental group 10 0.301 0.087 J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 19 Evaluation of denture base adaptation made by CT images (Figure 6) was at the mid sagittal line of denture bases on the respective master cast for all tested specimen (control and experimental groups), gap formation between the tissue surface of the denture base and master cast increased from the anterior to posterior side of palate and also from the alveolar ridge to the mid palatal line. However, the gap distance or volume could not be measured from the CT images due to the low resolution. A B Figure 6: Computerized tomography images for denture-cast sets: A. control group, B. experimental group DISCUSSION The present study was conducted to evaluate and compare the effect of addition (ZrO2:Al2O3nano-fillers mixture) to PMMA on some mechanical properties and denture base adaptation of heat cured acrylic denture base.The introduction of nanofillers into PMMA produced highly significant increase in the value of impact strengthwhen compared with control group. The increase in the impact strength could be due to thehigh interfacial shear strength between nanofiller and matrix resulted from the formation of cross-links or supra molecular bonding which cover or shield the Nano fillers which in turn prevent propagation of cracks. Also the crack propagation may be changed by good bonding between nanofiller and resin matrixresulted from interaction between the functional groups introduced by salinization process (28). The small size and high surface area and relatively low concentration may helped in a good distribution of these fillers that may cause a restricted motion of macromolecule chains and enhance mechanical properties (29), that means the PMMA nanocomposite has mechanical stability more than neat PMMA. Also, the transverse strength test result showed highly significant increase with nanocomposite when compared with control group.This increase in transverse strength may be explained on the basis of transformation toughening, when sufficient stress develops and crack begins to propagate, a transformation of ZrO2 and Al2O3 which depletes the energy of crack propagation, also, in this process expansion of ZrO2 and Al2O3 crystals occurs and places the crack under a state of compressive stress and crack propagation is arrested (25). Increase in transverse strength also could be due to transfer of stress from more flexible polymer to the higher modulus, more rigid and stiffer filler particles (25). The addition of nanofillers at 2wt.% to PMMA led to increase of surface hardness beyond that of pure PMMA, statistically was not-significant,this could be due to the relatively low concentration of the nanofillers used in the study, although, this improvement may be attributed to the inherent characteristics of the nanoparticles. Nanoparticles possess strong ionic interatomic bonding, giving rise to its desirable material characteristics, that is, hardness and strength. On these bases it may be expected when nanoparticles disperse in a matrix, they increase its hardness and strength (30). The surface roughness of modified PMMA with nanofiller was significantly increased when compared with control group.This is may be due to the differencein roughness of Nano particles and acrylic denture base matrix and also probably attributed to the difference in micro structural characteristics of the materials and the form of the particles (31). With regard to this study, the significantly increase insurface roughness can be considered uninfluential since microorganism colonization occurs when the roughness more than 0.2µm (32).The gap between denture base and cast was measured at 3 point (A, B, C) in two time to J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 20 evaluate denture base adaptation, where it mostly depend on polymerization shrinkage and water sorption of PMMA (33,34). So, in first measurement made immediately after deflasking showed a significant increase of gap in experimental groupwhen compared to control groupat point A and B, and non- significant increase of gap in experimental group at point C. This increase explained may be due to addition of nanoparticle lead to increase in thermal conductivity of acrylic resin (13,30), and degree of polymerization effected considerably by heat dissipation and thermal conductivity (35), lead to contraction of denture base due to further polymerization shrinkage that occur due to exposure to high temperature with reduction in the spaces between the chain of the polymer this result in agreement with Ogawaand and Hasegawa (36). In second time after incubation 14 day showed in a significant increase of gap in experimental group when compared to control groupat point A, and non-significant increase of gap in experimental group at point B and C. This result may be due to that the addition of nanoparticles to PMMA may decreased in water sorption when compared with unmodified PMMA (13,16), So decrease expansion of acrylic denture base which considered antagonist effect to polymerization shrinkage that occur in experimental group more than control group as discussed previously (37). The CT images of denture base-cast sets did show this tendency of gap formation in medial- lateral and anterior-posterior areas (Figure 6). These findings are also predictable with the results reported by Consani et al. (38), who compared the posterior border gap of the denture base-cast sets sectioned transversally at each area of the canine, molar and posterior ends. Moreover, the magnitude of the posterior border gap generally increased medially along the palatal vault reaching a maximum at the midline of the palate (39,40). REFERENCES 1. Darbar UR, Huggett R, Harrison A. Denture fracture-a survey. Br Dent J 1994; 176: 342-5. 2. Jagger DC, Harrison A, Jandt KD. Review: The reinforcement of dentures. J Oral Rehabil 1999; 26:185-94. 3. Meng TR Jr, Latta MA. Physical properties of four acrylic denture base resins. J Contemp Dent Pract 2005; 6: 93-100. 4. Kanie T, Fujii K, Arikawa H, Inoue K. Flexural properties and impact strength of denture base polymer reinforced with woven glass fibers. Dental Materials 2000; 16: 150–8. 5. Knott NJ. The durability of acrylic complete denture bases in practice. Quintessence Int 1989; 20: 341-3. 6. Ruffino AR. Effect of steel strengtheners on fracture resistance of the acrylic resin complete denture base. J Prosthet Dent 1985; 54: 75-8. 7. Teraoka F, Nakagawa M, Takahashi J. Adaptation of acrylic dentures reinforced with metal wire. J Oral Rehabil 2001 28; 937-42. 8. Goldberg AJ, Burstone CJ. The use of continuous fiber reinforcement in dentistry. Dent Mater 1992; 8: 197-202. 9. Sehajpal SB, Sood VK. Effect of metal fillers on some physical properties of acrylic resin. J Prosthet Dent 1989; 61: 746-51. 10. Zuccari AG, Oshida Y, Moore BK. Reinforcement of acrylic resins for provisional fixed restorations. Part I: Mechanical properties. Biomed Mater Eng 1997; 7: 327-43. 11. Jordan J, Jacob KL, Tannenbaum R, Shart MA, Jasiuk I. Experimental trends in polymer Nan composites-A review. Mater Sci Eng 2005; 393(1) 1-11. 12. Shi J, Bao Y, Huang Z, Weng Z. Preparation of PMMA-Nanomater calcium carbonate composites by in-situ emulsion polymerization. J Zhejiang University Sci 2004; 5(6) 709-13. 13. Jasim BS. The effect of silanized alumina Nano - fillers addition on some physical and mechanical properties of heat cured polymethyl methacrylate denture base material. M.Sc. Thesis, College of dentistry/University of Baghdad, 2013. 14. Safi IN. Evaluation the effect of modified Nano filler addition on some properties of the heat cure acrylic risen denture base material. M.Sc. thesis, College of Dentistry, University of Baghdad, 2011. 15. Majid S, Nabi MK, Abbas R. An experimental investigation of HA/AL2O3 nanoparticles on mechanical properties of restoration materials. Engineering Solid Mechanics 2014; 2:173-82. 16. Asar NV, Hamdi A, Turan K, Ilser T. Influence of various metal oxides on mechanical and physical properties of heat-cured polymethylmethacrylate denture base resins. J Adv Prosthodont 2013; 5: 241-7. 17. Becker CM, Smith DE, Nicholls J. The comparisons of denture –base processing technique. II. Dimensional changes due to processing. J Prosthet Dent 1977; 37: 450-90. 18. Anusavice KJ. Philip's science of dental material.10th ed. Philadelphia: W.B, Saunders Co.; 1996. p. 211, 220, 235, 237-271. 19. Craig RG, O'Brien WJ, Powers JM. Dental-materials properties and manipulation. 4th ed. St. Louis: CV Mosby Co.; 1990. p. 272-96. 20. Anderson GC, Schulte JK, Arnold TG. Dimensional stability of injection and conventional processing of denture base acrylic resin. J Prosthet Dent 1988; 60(3): 394-8. 21. Chen JC, Lacefield WR and Castleberry DJ. Effect of denture thickness and curing cycle on the dimensional stability of acrylic resin denture bases. Dent Mater J 1988; 4: 20-4. 22. ISO 179-1 International organization for standardization. Determination of Charpy impact properties: Part 1, 2000. 23. American Dental Association Specification No.12. Guide to dental materials and devices. 10th ed. Chicago, 1999; p: 32. 24. Ayad NM, Badawi M, Abdou A Fatah. Effect of reinforcement of high-impact acrylic resin with J Bagh College Dentistry Vol. 27(3), September 2015 Effect of addition Restorative Dentistry 21 zirconia on some physical and mechanical properties. Rev Clinical Dental 2008; 4(3): 145-51. 25. Anusavice KJ. Philips science of dental material. 11th ed. Middle East and African ed., Ch7, Ch22, 2008; p: 143-166,721-756. 26. Hussein YA. Influence of different pH of saliva and thermal cycling on the adaptation of different denture base materials. M.Sc. Thesis, College of Dentistry/ University of Baghdad, 2012. 27. Lee C, Bok S, Bae J, Hae-hyoung Lee. Comparative adaptation accuracy of acrylic denture bases evaluated by two different methods. Dent Mater J 2010; 29(4): 411-7. 28. Sun L, Gibson RF, Gordaninejad F, Suhr J. Energy absorption capability of nanocomposites: a review. Composites Science and Technology 2009; 69(14): 2392-409. 29. Gupta N, Brar BS, Woldesenbet E. Effect of filler addition on the compressive and impact properties of glass fiber reinforced epoxy. Bull Mater Sci 2001; 24:219-23. 30. Ellakwa AE, Morsy MA, El-Sheikh AM.Effect of aluminum oxide addition on the flexural strength and thermal diffusivity of heat-polymerized acrylic resin. J Prosthodont 2008; 17: 439-44. 31. Alnamel HA. The effect of silicon dioxide nano-fillers reinforcement on some properties of heat cure poly methymethacrylate denture base material. M.Sc. thesis, College of Dentistry, University of Baghdad, 2013. 32. Quirynen M, Marechal M, Busscher HJ, Weerkamp AH, Darius PL, Steerberghe D. The influence of surface free energy and surfsce roughness on early plaque formation: an in vivo study in man. J Clin Periodontol 1990; 17:138-44. 33. Wolfoardt J, Cleaton-Jones P, Fatti P. The influence of processing variables on dimensional changes of heat cured poly methyl methacrylate. J Prosth Dent 1986; 55: 518-25. 34. Salim S, Sadamori S, Hamada T. The dimensional accuracy of rectangular acrylic resin specimens cured by three denture base processing methods. J Prosthet Dent 1992; 67: 879-81. 35. Dhuru VB. Contemporary dental materials. Oxford University UK, 2003. 36. Ogawa T, Hasegawa A. Effect of curing environment on mechanical properties and polymerizing behavior of methyl- methacrylate auto polymerizing resin. J Oral Rehabil 2005; 32: 221-6. 37. Andrew J. Polymer chemistry properties and application. Carlverlag publisher, 2006; Ch. 23 p. 339- 45. 38. Consani RL, Domitti SS, Consani S. Effect of a new tension system, used in acrylic resin flasking, on the dimensional stability of denture bases. J Prosthet Dent 2002; 88: 285-9. 39. Laughlin A, David Eick J, Alan G, Leslie Y, Dorsy J. A comparison of palatal adaptation in acrylic denture bases using conventional and anchored polymerization techniques. J Prosthodont 2001; 10(4): 204-11. 40. Takamata T, Setcos JC, Phillips RW, Boone ME. Adaptation of acrylic resin dentures as influenced by the activation mode of polymerization. J Am Dent Assoc 1989; 119: 271- 6. الخالصة البولیمر ذات خواص میكانیكیة منخفضة، وتكیف قاعدة الطقم إلى األنسجة الكامنة مھم الستبقاء )الراتنجاألكریلك(میثاكریلیتلمادة قاعدة الطقم البولیمثی:خلفیة على قوة الصدمة والقوة وكسید االلمنیوم وأوكسید الزركونیوموكان الھدف من ھذه الدراسة ھو تقییم تأثیر خلیط الحبیبات النانویة أل. قرار قاعدة الطقمواست .لمادة قاعده طقم الراتنجاألكریلك الحراريقاعدة الطقم العرضیة، صالبة و خشونة السطح، وتكیف وفقا لنوع االختبار، ومن ثم تم تقسیم كل مجموعة إلى ) عشرونعینة لكل مجموعة(نة، تم تقسیم ھذه العینات إلى خمسمجموعات أعدت مائةعی: المواد والطرق أوكسیدالزركونیوم (٪ وزنا ل2عینات، وتضمنت المجموعة التجریبیة خلیط من ة كل مجموعة فرعیة تتكون من عشر)السیطرة والتجریبیة(مجموعتینفرعیتینھي ، تم قیاس ) Charpy(تم قیاس قوة الصدمة بواسطة آلة اختبار الصدمة). ZrO2:Al2O3 2:1(، وبنسبةمیثاكریلیتلالبولیمثی من مسحوق)اللمنیوموأوكسیدا وتم قیاس خشونة , (ShoreDdurometer) بواسطة مقیاس بینما تم قیاس صالبة السطح INSTRON)(القوة العرضیة بواسطة آلة اختبار انسترون ). CT(بواسطة المجھر الرقمي وتقییمھا من قبل جھاز التصویر المقطعي المحوسب قاعدة الطقم تم قیاس تكیف . Profilometerالسطح من قبل الذي تم قاعدة الطقم صانفیتكیف زیادة كبیرة للغایة في قوة الصدمة والقوة العرضیة، وزیادة غیر كبیرة في الصالبة، وزیادة كبیرة في الخشونة ونق: النتائج أما تقییم جھاز التصویر المقطعي المحوسب ، الفجوة . حصلت في المجموعة التجریبیة مقارنة بالمجموعة السیطرة) Cو A ،B(نقاط ھي)3(قیاسھ عند ثالث ومن قمة عظم الفكنب األمامي إلى الخلفي من سقف الحلق یظھر فیھ زیادة من الجا) السیطرة والتجریبیة(بین قاعدة الطقموالقالب الرئیسي لكال المجموعتین . إلى خط منتصف الحنك وفي نفس الوقت نقصان في تكیف الحراري النقي البولیمر الراتنجاألكریلكلدیھا خواص میكانیكیة أعلى من مادة النانو المركبة على أساس البولیمر:االستنتاج . قاعدة الطقم .قاعدة الطقمم االكریلیك ، حشوة النانو، الخواص المیكانیكیة، وتكیف قاعدة طق: الكلمات الرئیسیة