The antimicrobial effects of zinc oxide-calcium hydroxide mixture fillers: determining the ideal mixture ratio

  • Ali Nozari Department of Pediatric Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
  • Ali Karimkhani Department of Pediatric Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
  • Mohammad Motamedifar Department of Bacteriology and Virology, Shiraz HIV/AIDS Research Center, Institute of Health, Shiraz School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
  • Payam Arasteh Department of Foreign Languages and Linguistics, Shiraz University, Shiraz, Iran
Zinc oxide, Calcium hydroxide, Antimicrobial, Primary teeth, Root canal filling material


Background and Objectives: Although zinc oxide (ZO)-calcium hydroxide (CaOH) mixtures have been successful regarding their absorption rate compatibility with dissolving primary teeth, no study has been conducted on the appropriate mixture ratio to obtain effective antibacterial properties. In this study, we compared antibacterial activity of CaOH-ZO pastes using different mixture ratios sagainst Enterococcus faecalis as an important bacterium in root canal treatment failure.

Materials and Methods: Seven types of pastes were prepared in our laboratory. The first group included one gram of ZO+eugenol, second group included one gram of CaOH+distilled water, third group included 0.5gram ZO+0.5gram CaOH+distilled water (1:1), forth group included 0.75gramCaOH+0.25gramZO+distilled water (3:1), the fifth group included 0.33gram of CaOH+0.66gram of ZO+distilled water (1:2), the sixth group included 0.75gram of ZO+0.25 CaOH+distilled water (3:1), the seventh group included 0.66 gram CaOH+0.33 gram ZO+distilled water (2:1), and the final group included one gram of gelatin+distilled water (as the control group). These pastes were compared regarding their antibacterial effects against Enterococcus faecalis using agar diffusion and microdilution methods.

Results: Except for the control group, all prepared pastes showed antibacterial properties. Order of minimum inhibitory concentration for pastes were as followed: CaOH-ZO (1:3)=CaOH-ZO (1:2)>CaOH-ZO (1:1)>CaOH-ZO (3:1)=CaOH-ZO (2:1)>CaOH=ZO-eugenol. Order of minimum bactericidal concentration, which shows a weaker bactericidal effect, according to type of paste, were as followed: CaOH-ZO (1:3)>CaOH-ZO mixture (1:2)>CaOH-ZO mixture (1:1)>CaOH-ZO mixture (3:1)=CaOH-ZO (2:1)>CaOH=ZO-eugenol. Only CaOH-ZO (1:3) and CaOH-ZO (1:2), showed significantly weaker MICs and MBCs (p < 0.001).

Conclusion: Considering the limitations of an in-vitro study, in terms of anti-bacterial effects against Enterococcus faecalis, CaOH-ZO mixture (2:1) is equivalent to ZO-eugenol as the most commonly used material in polypectomy of primary teeth.


Bindra AS. Dental caries in the laboratory: developing a standard testing method for future research in caries prevention: Boston University; 2018.

Bertassoni LE, Orgel JP, Antipova O, Swain MV. The dentin organic matrix - limitations of restorative dentistry hidden on the nanometer scale. Acta biomaterialia. 2012;8(7):2419-33.

de Paz LEC. Aetiology of Persistent Endodontic Infections in Root-Filled Teeth. Apical Periodontitis in Root-Filled Teeth: Springer; 2018. p. 21-32.

Chow LC, Takagi S. Dental and endodontic filing materials and methods. Google Patents; 2018.

Praveen P, Anantharaj A, Venkataraghavan K, Rani P, Sudhir R, Jaya A. A review of obturating materials for primary teeth. SRM Journal of Research in Dental Sciences. 2011;2(1):42.

Pilownic KJ, Gomes APN, Wang ZJ, Almeida LHS, Romano AR, Shen Y, et al. Physicochemical and Biological Evaluation of Endodontic Filling Materials for Primary Teeth. Brazilian dental journal. 2017;28(5):578-86.

Jung S, Sielker S, Hanisch MR, Libricht V, Schäfer E, Dammaschke T. Cytotoxic effects of four different root canal sealers on human osteoblasts. PloS one. 2018;13(3):e0194467.

Garg N, Garg A, Kang R, Mann J, Manchanda SK, Ahuja B. A Comparison of Apical Seal Produced By Zinc Oxide Eugenol, Metapex, Ketac Endo and AH Plus Root Canal Sealers. Endodontology. 2014;26(2):252-8.

Jindal P, Khurana NS, Juneja R, Sharma H, Kumar V. Atypical Response of Gingival Tissue to Extruded Metapex. Journal of clinical and diagnostic research: JCDR. 2016;10(6):ZJ09.

Queiroz AMd, Assed S, Consolaro A, Nelson-Filho P, Leonardo MR, Silva RAB, et al. Subcutaneous connective tissue response to primary root canal filling materials. Brazilian Dental Journal. 2011;22(3):203-11.

Queiroz AMd, Nelson Filho P, Silva LABd, Assed S, Silva RABd, Ito IY. Antibacterial activity of root canal filling materials for primary teeth: zinc oxide and eugenol cement, Calen paste thickened with zinc oxide, Sealapex and EndoREZ. Brazilian dental journal. 2009;20(4):290-6.

Pinto DN, de Sousa DL, Araújo RBR, Moreira‐Neto JJS. Eighteen‐month clinical and radiographic evaluation of two root canal‐filling materials in primary teeth with pulp necrosis secondary to trauma. Dental Traumatology. 2011;27(3):221-4.

Al-Shwaimi E. Evaluation of antimicrobial effect of root canal sealers. Pakistan Oral & Dental Journal. 2011;31(2).

Segato RAB, Pucinelli CM, Ferreira DCA, Daldegan ADR, Silva RSd, Nelson-Filho P, et al. Physicochemical properties of root canal filling materials for primary teeth. Brazilian dental journal. 2016;27(2):196-201.

Smaïl‐Faugeron V, Courson F, Durieux P, Muller‐Bolla M, Glenny AM, Fron Chabouis H. Pulp treatment for extensive decay in primary teeth. The Cochrane Library. 2014.

Sapna H, Priti Kamlesh L, Dinesh Rao B, Shubha A. An in vitro evaluation of antimicrobial efficacy of primary root canal filling materials. Journal of Clinical Pediatric Dentistry. 2012;37(1):59-64.

Chawla H, Mani S, Tewari A, Goyal A. Calcium hydroxide as a root canal filling material in primary teeth--a pilot study. Journal of the Indian Society of Pedodontics and Preventive Dentistry. 1998;16(3):90-2.

Reddy S, Ramakrishna Y. Evaluation of antimicrobial efficacy of various root canal filling materials used in primary teeth: a microbiological study. Journal of Clinical Pediatric Dentistry. 2007;31(3):193-8.

Almaroof A, Niazi S, Rojo L, Mannocci F, Deb S. Influence of a polymerizable eugenol derivative on the antibacterial activity and wettability of a resin composite for intracanal post cementation and core build-up restoration. Dental Materials. 2016;32(7):929-39.

Desai S, Chandler N. Calcium hydroxide–based root canal sealers: a review. Journal of endodontics. 2009;35(4):475-80.

Barja-Fidalgo F, Moutinho-Ribeiro M, Oliveira MAA, Oliveira BHd. A systematic review of root canal filling materials for deciduous teeth: is there an alternative for zinc oxide-eugenol? ISRN dentistry. 2010;2011.

How to Cite
Nozari A, Karimkhani A, Motamedifar M, Arasteh P. The antimicrobial effects of zinc oxide-calcium hydroxide mixture fillers: determining the ideal mixture ratio. Iran J Microbiol. 11(3):239-245.
Original Article(s)