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Year : 2021  |  Volume : 32  |  Issue : 3  |  Page : 380-384
Estimation of IZOD impact strength between different concentrations of chitosan-reinforced denture base resins

1 Department of Prosthodontics, Sri Ramaswami Memorial Dental College, Ramapuram, Chennai, Tamil Nadu, India
2 Department of General Surgery, Sri Ramaswami Memorial Dental College, Ramapuram, Chennai, Tamil Nadu, India

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Date of Submission24-Jan-2021
Date of Decision23-Jun-2021
Date of Acceptance09-Aug-2021
Date of Web Publication23-Feb-2022


Background: Poly-methyl methacrylate (PMMA) is an universally acceptable denture base material. Efforts are made to increase the applications with the addition of new constituents. Chitosan has established antifungal properties. The mechanical properties of Chitosan–denture base composite is less evaluated in the literature. This study estimates the differences in impact strength of material for different concentrations of chitosan-reinforced denture base resins. Aim: The study estimated the differences in IZOD impact strength of denture base resin reinforced with 0%, 5%, 10% and 15% of chitosan by weight. Materials and Methods: The acrylic samples were fabricated in according to ISO 180 regulations. The study had four test groups (n = 10). ACh0 was the control group with no reinforcements. ACh5, ACh10 and ACh15 had chitosan reinforcement of 5%, 10% and 15% by weight. The samples were processed by conventional heat polymerization cycle and tested in IZOD impact testing machine. The data were recorded and statistically analyzed with Kruskal–Wallis test. Results: The mean impact strength was high in ACh5 (4.25 ± 1.05 kJ/m2) compared to ACh0 (2.88 ± 0.60 kJ/m2), ACh10 (3.63 ± 0.40 kJ/m2), ACh15 (3.38±0.60 KJ/m2). Statistically significant differences between the test groups was determined by Kruskal–Wallis and post hoc Bonferroni test (Chi-square = 12.843, P = .005, df = 3). Conclusion: The impact strength of denture base resin increased with 5% chitosan compared with other percentage of chitosan. No statistical significant relationship was observed between the groups.

Keywords: Chitosan, chitosan-reinforced denture base, denture base resin, heat cure acrylic resin, impact strength

How to cite this article:
Chander N G, Jayaraman V. Estimation of IZOD impact strength between different concentrations of chitosan-reinforced denture base resins. Indian J Dent Res 2021;32:380-4

How to cite this URL:
Chander N G, Jayaraman V. Estimation of IZOD impact strength between different concentrations of chitosan-reinforced denture base resins. Indian J Dent Res [serial online] 2021 [cited 2022 Aug 16];32:380-4. Available from:

   Introduction Top

Poly-methyl methacrylate (PMMA) is a widely used denture base material. It is a versatile material and possesses superior properties compared to other denture base materials.[1],[2] Denture base fracture was anticipated in adverse clinical situations.[3],[4] Research was done to improve the mechanical, physical and biological properties.[5],[6],[7] Various fillers, nanomaterials, antimicrobials and antifungal agents were added but lacunae exist in finding the ideal materials with advanced properties.[8],[9],[10] Among the superior properties, the antifungal function is significant for elderly as it aids in controlling candidiasis.

Chitosan is a natural polysaccharide obtained from sea shell. It exhibits significant physical, mechanical and biological properties.[11] The biocompatibility, biodegradability, antimicrobial and bioactive properties aid in extensive medical and dental applications.[12] It is widely used in tissue engineering, wound healing, drug delivery, remineralization of teeth, bone regeneration and improving the properties of various dental materials.[11],[12],[13] The most significant application of chitsoan was antifungal action that can be effectively used in prosthodontics. The studies have established the antifungal properties of chitosan with PMMA.[14],[15] Less studies were done to estimate the mechanical properties.

The fracture of denture occurs due to impact forces in adverse clinical situations.[16],[17] The evaluation of impact strength of denture base materials is essential to avoid impact failure. Impact strength is the capacity of the material to withstand the sudden applied load. Clinically, it can lead to failure due to dropping of denture. The influence of chitosan-reinforced denture base material on impact strength is critical and is estimated. The null hypothesis of the study is that there is no difference in the impact strength between the various concentrations of chitosan-reinforced denture base resins.

   Materials and Methods Top

The study was approved by institutional review board. The study followed the ISO 180 guidelines. The master brass dye for the test samples was CAD milled in accordance to ISO dimension of 80 mm × 10 mm × 4 mm. The brass dye was duplicated with additional silicone impression material from which 40 wax patterns were made.

The study samples were divided into four groups in accordance to the percentage of chitosan-reinforced denture base resins. ACh0 was the control group with no chitosan in denture base resin. ACh5, ACh10, ACh15 contained 5%, 10% and 15% chitosan by weight reinforced denture base resins. The chitosan (Sigma Aldrich, Product number 448869, CAS: 9012-76-4, MDL: MFCD00161512) was added to denture base resin polymer (Dental Products of India, product no: 11811) and ball milled (PM 100 CM, Retsch GmbH) for 10 minutes at 300 RPM for homogenized mixture. The reinforced samples were heat cure processed by compression moulding technique. The wax patterns made by duplicating the dye was flasked, dewaxed and heat cure processed in accordance to test samples groups following conventional long heat polymerization cycle. The fabricated samples were finished and polished conventionally with different grits of sandpaper and pumice polishing. The specimen was rechecked for dimensions, porosity and deformities. The finished samples were stored in water for 48 hours earlier to testing.

The samples were tested in IZOD impact testing machine (Frank Bacon machinery sales company, Warren, MI). The samples were notched to the dimension of 8 mm. The acrylic samples were clamped vertically to the impact testing machine with the notched side facing the hammering pendulum [Figure 1]a and [Figure 1]1b. The pendulum hammered horizontally at a speed of 5 J. The data was recorded in KJ/m2 and analyzed by Kruskal–Wallis test using, Statistical Package for the Social Sciences software (SPSS 25 -2017, IBM SPSS Statistics). One sample from each group was evaluated with scanning electron microscope (FEI Quanta FEG 200). The fracture area, matrix and distribution of particles were observed [Figure 2], [Figure 3], [Figure 4], [Figure 5].
Figure 1: (a) – IZOD impact testing machine. (b) – Testing of samples

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Figure 2: SEM image of control group

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Figure 3: SEM Image of ACh5

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Figure 4: SEM image of ACh10

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Figure 5: SEM image of ACh15

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   Results Top

The descriptive statistics of the study is listed in [Table 1]. The mean impact strength of control group was 2.88 ± 0.60 kJ/m2. The higher impact strength was observed in ACh5 (4.25 ± 1.05 kJ/m2). The impact strength decreased with higher concentration of chitosan ACh10 (3.63±0.40 kJ/m2) and ACh15 (3.38±0.0.60 kJ/m2). Kruskal–Wallis test estimated the differences on impact strength between different groups [Table 2] and [Table 3]. Statistically significant differences between the test groups was found (Chi-square = 12.843, P > 0.05, df = 3) with a mean rank impact strength score of 12.10 for ACh0, 28.70 for ACh5, 22.30 for ACh10 and 18.90 for ACh15. (P > 0.05). The post hoc test [Table 4] revealed more significant difference between ACh0 and ACh5 than other groups that were statistically insignificant.
Table 1: Descriptive statistics of test specimen

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Table 2: Kruskal–Wallis test ranks

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Table 3: Kruskal–Wallis test statistics

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Table 4: Post hoc test with Bonferroni corrections

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   Discussion Top

The study rejected the null hypothesis that there were no differences in the impact strength between various concentrations of chitosan-reinforced denture base samples. The fracture of denture occurs in both intra and extra oral environment. The fracture in intraoral environment is mostly due to fatigue fracture and in extra oral environment it is due to impact forces.[16],[17] Majority of the studies determine flexural strength for the intraoral fracture of the material. In most clinical situations, the denture fracture happens due to adverse impact forces.[18] Many studies were done on impact strength of various denture base reinforcement materials.[19],[20],[21],[22],[23],[24],[25] Fewer studies were done to evaluate the impact strength of chitosan reinforcement on denture base resin. The presence of antimicrobial and antifungal constituents in the denture base material can support elderly individuals due to the compromised immunity. Candidiasis is one of the commonest infection found in elderly due to poor intraoral environment. The antifungal properties of chitosan was established in the literature and can be vital in controlling the fungal infection in elderly.[14],[15]

The study established higher impact strength at 5% concentration of chitosan by weight. The impact strength decreased with higher concentrations, but the strength was greater than the control group. The higher strength in ACh5 (4.25 ± 1.05 kJ/m2) can be attributed to better distribution of particles. The SEM images established equal distribution of particles [Figure 2], [Figure 3], [Figure 4], [Figure 5]. The particle occupying the pore spaces of acrylic to obtain the improved strength. Studies with various filler particles have proven the theory of crosslinking, improved copolymerization, surface hydrophobicity and decreased particle agglomerations.[19],[20],[21],[22],[23] These theories were applicable for improved strength. The concepts are generalized for chitosan–acrylic composite reinforcement. Additionally, the availability of increased materials at the grain boundary and the compaction displayed improved impact strength. The molecular interaction for bonding is better in 5% compared to the other test groups. However, the mechanism of interactions is unclear. Lesser studies have evaluated the organic molecular interaction. More studies are required to establish the molecular interaction.

The decrease in strength in ACh10 (3.63±0.40 kJ/m2) and ACh15 (3.38±0.0.60 kJ/m2) can be due to decreased chemical bonding and increase in chitosan particles. The decrease in strength can be attributed to poor crosslinking and copolymerization.[24],[25],[26] Moreover, the increase in filler particles can cause microcracks and porosities during polymerization and can lead to decrease in impact strength.[27],[28]

The impact strength of ACh10 and ACh15 were lesser than ACh5, but it is higher compared to control groups. The even distribution of particles can aid in improved strength of the composite materials compared to non-reinforced materials. The ball milling of the composite material aided in even distribution, improved bonding and better material properties compared to the control group. The even distribution of particles was substantiated with SEM images. The earlier studies on chitosan have used hand mixing or low profilic mixing devices. The use of ball milling in this study has additionally improved properties due to improved distribution and chemical interactions.

Extensive studies were done with many inorganic particles' reinforcements to acrylic. Few studies were done with micro and nano-organic particles. The literature has fewer data on the nature of interaction of organic particles with acrylic. Extensive studies are required to obtain the understanding of bonding between chitosan and denture base resin. The differences in the guidelines for estimation can also influence the impact strength. It is essential in future studies that more definitive guidelines have to be established for determining the impact strength of denture base resins and its modifications.

   Conclusion Top

Within the limitations, the study established that the mean impact strength was higher in ACh5% and the impact strength decreased with increase in percentage of chitosan.


  • Nanotechnology Research Centre (NRC), SRMIST for extending the research facilities.
  • DST-FIST program no.SR/FST/College-110/2017, Government of India in Easwari Engineering College, Chennai, Tamil Nadu, India for providing the research facilities.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Chander NG. Polymethyl metha acrylate denture base: An overview. J Indian Prosthodont Soc 2018;18:87-8.  Back to cited text no. 1
[PUBMED]  [Full text]  
Zafar MS. Prosthodontic applications of polymethyl methacrylate (PMMA): An update. Polymers (Basel) 2020;12:2299.  Back to cited text no. 2
McCord J, Grant A. Identification of complete denture problems: A summary. Br Dent J 2000;189:128-34.  Back to cited text no. 3
Critchlow SB, Ellis JS, Field JC. Reducing the risk of failure in complete denture patients. Dent Update 2012;39:427-36.  Back to cited text no. 4
Gad MM, Fouda SM, Al-Harbi FA, Näpänkangas R, Raustia A. PMMA denture base material enhancement: A review of fiber, filler, and nanofiller addition. Int J Nanomedicine 2017;12:3801-12.  Back to cited text no. 5
Vikram S, Chander NG. Effect of zinc oxide nanoparticles on the flexural strength of polymethylmethacrylate denture base resin. Eur Oral Res 2020;54:31-5.  Back to cited text no. 6
Chen SY, Liang WM, Yen PS. Reinforcement of acrylic denture base resin by incorporation of various fibers. J Biomed Mater Res 2001;58:203-8.  Back to cited text no. 7
Vallittu PK. A review of fiber-reinforced denture base resins. J Prosthodont 1996;5:270-6.  Back to cited text no. 8
Sivakumar I, Arunachalam KS, Sajjan S, Ramaraju AV, Rao B, Kamaraj B. Incorporation of antimicrobial macromolecules in acrylic denture base resins: A research composition and update. J Prosthodont 2014;23:284-90.  Back to cited text no. 9
Gad MM, Fouda SM. Current perspectives and the future of Candida albicans-associated denture stomatitis treatment. Dent Med Probl 2020;57:95-102.  Back to cited text no. 10
Jarmila V, Vavríková E. Chitosan derivatives with antimicrobial, antitumour and antioxidant activities--a review. Curr Pharm Des 2011;17:3596-607.  Back to cited text no. 11
Muxika A, Etxabide A, Uranga J, Guerrero P, de la Caba K. Chitosan as a bioactive polymer: Processing, properties and applications. Int J Biol Macromol 2017;105:1358-68.  Back to cited text no. 12
Mohebbi S, Nezhad MN, Zarrintaj P, Jafari SH, Gholizadeh SS, Saeb MR, et al. Chitosan in biomedical engineering: A critical review. Curr Stem Cell Res Ther 2019;14:93-116.  Back to cited text no. 13
Song R, Zhong Z, Lin L. Evaluation of chitosan quaternary ammonium salt-modified resin denture base material. Int J Biol Macromol 2016;85:102-10.  Back to cited text no. 14
Gondim BLC, Castellano LRC, de Castro RD, Machado G, Carlo HL, Valença AMG, et al. Effect of chitosan nanoparticles on the inhibition of Candida spp. biofilm on denture base surface. Arch Oral Biol 2018;94:99-107.  Back to cited text no. 15
Al-Harbi FA, Abdel-Halim MS, Gad MM, Fouda SM, Baba NZ, AlRumaih HS, et al. Effect of nanodiamond addition on flexural strength, impact strength, and surface roughness of PMMA denture base. J Prosthodont 2019;28:e417-25.  Back to cited text no. 16
Smith DC. Acrylic denture mechanical evaluation; mid-line fracture. Br Dent J 1961;110:257-67.  Back to cited text no. 17
Choksi RH, Mody PV. Flexural properties and impact strength of denture base resins reinforced with micronized glass flakes. J Indian Prosthodont Soc 2016;16:264-70.  Back to cited text no. 18
[PUBMED]  [Full text]  
Somani MV, Khandelwal M, Punia V, Sharma V. The effect of incorporating various reinforcement materials on flexural strength and impact strength of polymethylmethacrylate: A meta-analysis. J Indian Prosthodont Soc 2019;19:101-12.  Back to cited text no. 19
[PUBMED]  [Full text]  
Gupta A, Tewari RK. Evaluation and comparison of transverse and impact strength of different high strength denture base resins. Indian J Dent Res 2016;27:61-5.  Back to cited text no. 20
[PUBMED]  [Full text]  
Al-Dwairi ZN, Tahboub KY, Baba NZ, Goodacre CJ. A comparison of the flexural and impact strengths and flexural modulus of CAD/CAM and conventional heat-cured polymethyl methacrylate (PMMA). J Prosthodont 2020;29:341-9.  Back to cited text no. 21
Murthy HB, Shaik S, Sachdeva H, Khare S, Haralur SB, Roopa KT. Effect of reinforcement using stainless steel mesh, glass fibers, and polyethylene on the impact strength of heat cure denture base resin – An in vitro study. J Int Oral Health 2015;7:71-9.  Back to cited text no. 22
Kango S, Kalia S, Celli A, Njuguna J, Habibi Y, Kumar R. Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—A review. Prog Polym Sci 2013;38:1232-61.  Back to cited text no. 23
Kanie T, Arikawa H, Fujii K, Ban S. Impact strength of acrylic denture base resin reinforced with woven glass fiber. Dent Mater J 2003;22:30-8.  Back to cited text no. 24
Faot F, Costa MA, Del Bel Cury AA, Rodrigues Garcia RC. Impact strength and fracture morphology of denture acrylic resins. J Prosthet Dent 2006;96:367-73.  Back to cited text no. 25
Kanie T, Fujii K, Arikawa H, Inoue K. Flexural properties and impact strength of denture base polymer reinforced with woven glass fibers. Dent Mater 2000;16:150-8.  Back to cited text no. 26
Praveen B, Babaji HV, Prasanna BG, Rajalbandi SK, Shreeharsha TV, Prashant GM. Comparison of impact strength and fracture morphology of different heat cure denture acrylic resins: An in vitro study. J Int Oral Health 2014;6:12-6.  Back to cited text no. 27
Salman AD, Jani GH, Fatalla AA. Comparative study of the effect of incorporating SiO2 nano-particles on properties of poly methyl methacrylate denture bases. Biomed Pharmacol J 2017;10:1525-35.  Back to cited text no. 28

Correspondence Address:
Dr. N Gopi Chander
Department of Prosthodontics, Sri Ramaswami Memorial Dental College, Ramapuram, Chennai - 600 089, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.ijdr_71_21

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3], [Table 4]


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