Original article
Evaluation of the Candida albicans removal and mechanical properties of denture acrylics cleaned by a low-cost powered toothbrush

https://doi.org/10.1016/j.jpor.2014.06.002Get rights and content

Abstract

Purpose

To investigate the effects of using a low-cost powered toothbrush for cleaning on dental prostheses made of heat polymerized poly(methyl methacrylate), PMMA.

Methods

Heat cured PMMA specimens beam with the dimensions of 45.0 mm × 6.5 mm × 4.5 mm were fabricated. The specimens were kept in water storage at 37 °C constant temperature for 0, 1, 7, 15, 30 and 60 days and randomly assigned for testing or control. Test specimens underwent brushing by using a powered toothbrush at an applied force of 2.00 N for 22 min with water as medium. Surface roughness measurement (Ra), flexural strength and efficacy of brushing to remove coated Candida albicans biofilm were investigated.

Results

The results of the mean surface roughness value and the flexural strength were analysed by using two-way ANOVA and Tukey post hoc test at 5% significance level. In general, the specimens showed no significant changes in flexural strength after brushing. However, the flexural strength and the surface roughness value were significantly lower in specimens group after 7 days in water storage compared to the control. SEM micrographs of post-brushed specimens revealed satisfactory removal of C. albicans biofilm.

Conclusion

A low-cost powered toothbrush together with a liquid medium successfully removed C. albicans biofilm on dental acrylic PMMA-based prostheses, without compromising the mechanical properties.

Introduction

Cleaning of dentures to maintain a good denture hygiene is essential for the prevention of stomatitis related to denture wearing [1], [2]. The old and frail elderly people and their caregivers may be unable to perform the denture hygiene adequately [3]. The reason cited includes diminished manual dexterity, impaired vision, or chronic illnesses [4], [5]. The ability to perform self-care gradually decrease with deteriorating physical condition through advancing age, and the assistance of the caregiver in daily oral care becomes indispensable [4]. However, good and adequate oral and denture hygiene maintenance by caregivers is not always possible because of time constraints, lack of cooperation, the lack of perceived need and the unavailable knowledge to them. This is an undesirable outcome for aged individuals, where the commitment to a healthy life at old age may be half-hearted and the results of oral diseases prevention compromised [6], [7].

Good oral health has been reported as an important component of overall health and quality of life [8]. The various aspects of issues concerning oral health of the elderly are extensively debated in the literature, such as the professional care by dentists, the social economic impacts and the individual patient's needs [9].

Mechanical cleaning of dental prostheses using brushes was reported to be underutilized [8], [10]. The fact remains that oral health care has always been low in priority compared to the medical care, in general. Priority for edentulous patients care which includes prostheses construction and daily denture hygiene maintenance is even lower [11]. The implication of this is that only minimal resources are allocated for denture hygiene practice, be it at the institutional or individual level.

A recent study by Nishi et al. suggested that some assistance was necessary for the elderly to effectively use denture brushes. In addition, they also reported that the quantity of microorganisms was significantly lower among the denture brush users than non-users among the outpatient subjects compared to the nursing home subjects surveyed [12]. It is noteworthy that increasing the brushing efficiency during denture cleaning with brushes should merit a good and thorough investigation.

It was also reported that chemical cleaning method using denture cleansers may allow residual biofilm retention that could lead to regrowth and denture colonization of microorganisms [13]. Thus, the use of hypochlorite soaking solution has been the established and efficacious method to eliminate Candida albicans biofilms from the surfaces of dentures [13], [14]. However, whether the chemical cleaning could completely clean the denture is questionable. Therefore, additional mechanical cleaning methods are required to disrupt and remove biofilms attached to surfaces of dentures. Nevertheless, the mechanical cleaning might give an unknown opportunity to increase the surface roughness, which might lead to mechanical properties change and would lead to increased denture plaque retention and microorganism accumulation on the denture surfaces [15], as well as to promote the initial adhesion of microorganisms [16].

In light of this, in the current study, the use of a simple design unidirectional rotating head battery powered toothbrush that is relative affordable in cost, might be a small step forward in oral disease prevention among the aged population. The resultant effects of brushing produced by powered toothbrush consisted of surface roughness, flexural strength and C. albicans biofilm removal were investigated in current experiment. The removal effectiveness of biofilm was intuitively observed through SEM. The hypothesis was that water storage has no effect on cleaning of the PMMA material.

Section snippets

Materials and methods

Poly(methyl methacrylate), PMMA of the brand Trevalon C (DENTSPLY, De Tray Division, Weybridge, UK) in a liquid monomer and powder polymer form (heat polymerization type) was used for fabrication of the specimen beam. A total of 244 specimen beams were prepared for this experiment. Specimens with the dimension of 45.0 mm × 6.5 mm × 4.5 mm were fabricated in stainless steel moulds. The PMMA used was mixed at the powder to liquid ratio of 2.4:1.0 and processed according to manufacturer's instruction and

Surface roughness

The mean ± standard deviation of the Ra value of surfaces of PMMA specimens before brushing was 0.29 ± 0.06 μm. After brushing it was 0.27 ± 0.06 μm which was significantly smaller than for brushing (p = .022). Among the specimen groups, the number of days in water storage affected the Ra before and after brushing differently (p = .006), with the lowest Ra recorded from specimen groups after 7 days in water storage, compared to the group with no water storage.

A two-way ANOVA (Table 1) was conducted to

Discussion

Surface roughness is associated with the surface finishing of a dental prosthesis. The highly polished surface of PMMA dental prosthesis has a low surface roughness value Ra compared to a coarse finish surface. In the current experiment the specimens of PMMA were not subjected to post fabrication finishing and polishing. Thus, there was an observation of surfaces of PMMA specimens after brushing protocol that showed a decrease in the surface roughness value. This might have been due to the

Conclusions

These experiments in this laboratory pilot study have led us to the following conclusions:

  • 1.

    A battery powered toothbrush with a compact head design and a simple unidirectional rotating movement might be a suitable device for hygiene maintenance of acrylic resin dental prostheses.

  • 2.

    Surfaces of the PMMA specimens after brushing with a powered toothbrush demonstrated no adverse effect in flexural strength and no increase in surface roughness value (Ra) when water was used as medium.

  • 3.

    C. albicans biofilm

Conflict of interest statement

The authors would like to certify that there is no conflict of interest with any financial organization regarding the material discussed in this manuscript.

Acknowledgements

This work was done in partial fulfilment of the requirements of the degree of MSc(DMS) for Dr Chow-Ming Tan at the Faculty of Dentistry, The University of Hong Kong. Part of the results of this paper has been presented at the 2013 IADR-Asia Pacific Region Session, Bangkok, Thailand.

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