ORIGINAL RESEARCH Year : 2022  |  Volume : 13  |  Issue : 4  |  Page : 142-144

A Comparison of Solubility Among Zinc Oxide Eucalyptus and Zinc Oxide Eugenol: An In Vitro Study

Hella Thamer Zedan, Zainab Juma Jafar
Department of Pedodontic and Preventive Dentistry, College of Dentistry, University of Baghdad, Baghdad, Iraq

Date of Submission21-Sep-2022Date of Decision25-Oct-2022Date of Acceptance26-Oct-2022Date of Web Publication12-Dec-2022

Correspondence Address:
Hella Thamer Zedan
Department of Pedodontic and Preventive Dentistry, College of Dentistry, University of Baghdad, Baghdad
Iraq

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/denthyp.denthyp_116_22

Introduction: We aimed to compare solubility between zinc oxide eugenol and zinc oxide eucalyptus. Methods: One hundred and twenty standardized plastic ring molds were constructed and filled with zinc oxide eugenol and zinc oxide eucalyptus. The specimens were allowed to dry for 24 hours and then weighed to the nearest 0.0001 g. Then divided randomly into three groups and immersed in distilled water for 1, 7, and 21 days. Then samples were removed from the solution and allowed to dry for 24 hours. Then they were weighed again, the percentage of weight loss was then determined as solubility. Data analyzed by two-way repeated measures ANOVA and the Tukey’s post-hoc test using MedCalc 20.104. Results: Zinc oxide eucalyptus solubility is more than zinc oxide eugenol. All tests of between-subjects effects and within-subjects effects showed statistically significant differences (P < 0.001). Conclusion: The 1st day results showed solubility of not more than 3% following storage in distilled water which meet the requirements of ISO 6876, where both zinc oxide-eugenol (ZOE) (0.05%) and zinc oxide eucalyptus (0.15%) satisfied these criteria.

Keywords: Obturation material, water solubility, zinc oxide eugenol, zinc oxide eucalyptus

How to cite this article:
Zedan HT, Jafar ZJ. A Comparison of Solubility Among Zinc Oxide Eucalyptus and Zinc Oxide Eugenol: An In Vitro Study. Dent Hypotheses 2022;13:142-4
  Introduction 

It is well-known that the solubility of the root canal filling materials is undesirable, because the process of dissolution may result in gaps and voids along. These spaces would provide an environment for bacterial colonization and passage of microorganisms and their products into the periapical tissues.[1] Moreover, soluble components leaching from the root canal filling may have undesirable biological effects on the surrounding healthy tissues.[2]

Since the 1890s the zinc oxide-eugenol (ZOE) cement has been widely used as the main endodontic filling for primary teeth, due to easy handling, excellent cavity sealing ability, bactericidal properties, and a sedative effect on sensitive teeth.[3] But known by its flaws like its cytotoxicity[4],[5] due to eugenol ions as demonstrated in human osteoblastic cells to decrease dehydrogenase enzyme activity in dose-related manner.[6] So there is a need to replace eugenol oil by another oil, which seen to be better replaced by natural oils.[7] It is widely believed that antioxidant activities of natural herbal medicines are also effective in reducing the toxicities of toxic agents or other drugs.[8]

As today, various endodontic filling materials are available in the marked that compete for more accuracy and prosperities such as the mineral trioxide aggregate (MTA). However, their cost is still a major concern. Cost–benefit considerations make ZOE material as the most widely used in clinical dentistry, especially in developing countries.[3] As an attempt to improve the qualities of such valued material and as a continue of a previous research[9] where it was introduced the zinc oxide eucalyptus which it had a better antimicrobial activity, in this study we aimed to assess the solubility of zinc oxide eucalyptus.

  Material and Methods 

The study protocol approved by the Central Ethical Committee in the College of Dentistry/University of Baghdad (Approval number: 280, Date: March 31, 2021).

Sample size was determined using G power software 3.1.9.7 (http://www.gpower.hhu.de/) with 95% power, effect size of 0.7, significance level at 0.05, and 10% dropout ratio, a sample size of 40 is required. However, 120 samples for each material were divided randomly (using https://www.random.org/) into three groups (1, 7, and 21 days). Each sample was intended for single immersion for more accuracy.[10]

Before and after weighing of the specimens has been used for stating the best indicator of the amount of the solubility.[10]

The solubility of the materials was calculated by using the following formula:

Solubility = W0–Wt/W0 ×100%

W0: is the weight of the sample before immersion.

Wt: is the weight of the sample after immersion period.

After mixing and blending of the tested materials (one scoop [0.2 g] zinc oxide powder [Produits Dentaires SA , Vevey, Switzerland] and seven drops [0.07 cm3] eugenol oil [Produits Dentaires SA , Vevey, Switzerland] or eucalyptus oil [prepared in agriculture school of Baghdad University]),[11] each material was molded to fit plastic ring molds having an internal diameter of (20.0 ± 1 mm) and a height of (1.5 ± 0.5 mm), pressing them by metal forming and two glass plates (600 mg). All molds were covered by glass plates to avoid air entrapment and left to set at 37°C for 24 hours for complete setting prior immersion.

After cleaning all molds, a copper wire was fixed at each mold to hang the specimens in a plastic dish that the specimens did not touch and the sealers remained undisturbed in the dish.

Prior to the immersion of the samples, the whole molds were numbered and weighed thrice prior to use (accuracy ± 0.0001 g) using calibrated electronic micro-balance (Sartorius, Goettingen, Germany) thrice and the average reading was calculated.

Each one of the samples was kept separately each in glass bottle containing 50 mL of distilled water at 37°C in such a way that both surfaces of each sample were freely accessible to the liquid.

After 24 hours group 1 was removed from the distilled water using tweezers, grasping merely the plastic part, dehydrate for 1 hour at 37°C. After that, each disc was weighed to the microgram level.[10] This was repeated after 7 days for group 2 and then after 21 days for group 3.

During the testing time, the water in the bottles was not be altered or added to. At 1 day, 7 days, and 21 days, the desiccation and weighing operation was carried out.

Data analyzed by two-way repeated measures ANOVA and the Tukey’s post-hoc test using MedCalc 20.104 (MedCalc Software Ltd., Ostend, Belgium).

  Results 

Results of the present study showed that the solubility of zinc oxide eucalyptus is higher than zinc oxide eugenol [Figure 1]. All tests of between-subjects effects and within-subjects effects showed statistically significant differences (P < 0.001).

Figure 1 Bar plot showed mean and standard deviation of solubility percentage among different study groups and timelines. To better understand the differences in 1st day, the results also showed with logarithmic scale.

Click here to view

  Discussion 

The results present in vitro study, showed that zinc oxide eucalyptus had more solubility than ZOE in each tested period, and the solubility increased over time.

According the International Standard (ISO) 6876 for root canal sealing materials and the ANSI/ADA Specifications No. 57 and No. 30, the solubility of a sealer will not go beyond 3% mass fraction after immersion in water for 24 hours.[12],[13],[14]

The 1st day results showed solubility of not more than 3% following storage in distilled water which meet the requirements of ISO 6876, where both ZOE (0.05%) and zinc oxide eucalyptus (0.15%) satisfied these criteria.

This agreed with findings from earlier investigations.[15],[16],[17] Also, the results of this study coincide with the results from other in vivo studies, in which ZOE sealer proved to possess good sealing ability.[1],[18]

The 7th day results showed the solubility rate of ZOE remains within the acceptable level even after 7 days (2.43%), which indicates good resistance to solubility. The results of this study disagree with the findings of Schäfer and Zandbiglari,[18] in which the ZOE showed a consistent continuous and marked weight loss over 21 days but it agrees with zinc oxide eucalyptus (3.13%) that go beyond the accepted rate of 3%.

Advantages and limitation

For more accurate measurements, each sample was immersed for one time, eliminating the risk of inadvertent weight loss of the specimens owing to repeated drying and immersion. Following immersion, the samples were rinsed with distilled water removing any loose decomposition debris, for not recording any potential excess weight.

With respect to the limitations of in vitro studies, there is no absolute relationship between in vivo testing of the disintegration of the cement and the test in vitro, because of the different root canal environment and the influence of fluids and chemicals which often occur intraorally. In vivo studies as with saliva, crevicular, and body fluids on animal models recommended.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 

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  [Figure 1]