Clinical trial for evaluation of Ricinus communis and sodium hypochlorite as denture cleanser

Abstract The development of opportunistic infections due to poor denture hygiene conditions justified the search for effective hygiene protocols for controlling denture biofilm. Objective This study evaluated Ricinus communis and sodium hypochlorite solutions in terms of biofilm removal ability, remission of candidiasis, antimicrobial activity, and participant satisfaction. Material and Methods It was conducted a controlled clinical trial, randomized, double-blind, and crossover. Sixty-four denture wearers with (n=24) and without candidiasis (n=40) were instructed to brush (3 times/day) and immerse their dentures (20 min/day) in different storage solutions (S1 / S2: 0.25% / 0.5% sodium hypochlorite; S3: 10% R. communis; S4: Saline).The trial period for each solution was seven days and a washout period of seven days was used before starting the use of another solution. The variables were analyzed at baseline and after each trial period. The biofilm of inner surfaces of maxillary dentures was disclosed, photographed, and total and dyed areas were measured (Image Tool software). The percentage of biofilm was calculated. Remission of candidiasis was assessed by visual scale and score were attributed. Antimicrobial activity was assessed by the DNA-Checkerboard hybridization method. Patient satisfaction was measured using a questionnaire. Results S1 (4.41±7.98%) and S2 (2.93±5.23%) were more effective then S3 (6.95±10.93%) in biofilm remotion(P<0.0001). All solutions were different from the control (11.07±11.99%). S3 was the most effective solution in remission of candidiasis (50%), followed by S1 (46%). Concerning antimicrobial action, S1/S2 were similar and resulted in the lowest microorganism mean count (P=0.04), followed by S3. No significant differences were found with patient’s satisfaction. Conclusions 10% R. communis and 0.25% sodium hypochlorite were effective in biofilm removal, causing remission of candidiasis and reducing the formation of microbial colonies in denture surfaces. All solutions were approved by patients.

However, these solutions may adversely affect physical and mechanical properties of the denture 4,17 .
In addition, the unpleasant taste and odor of NaClO may cause some discomfort for patients, although there aren't studies that have evaluated the extent acceptance of antiseptic solutions by denture wearers and, therefore, their usage on a regular basis could be lower than shown in short-term trials 29 . Therefore, studies using lower concentrations are needed.
The method chosen for home prosthetic care should be effective in removing organic and inorganic debris, exhibit fungicidal and bactericidal properties, be compatible with the structural material of the prosthesis, be non-toxic to users, have low cost, and be easy to handle. Since most of the current methods used for denture hygiene do not present all these characteristics, numerous studies have protocol 2,4,7,10,16,19,20,[22][23][24]26,27,29 .
The R. communis solution has been studied as a potential denture cleaner, since it acts as a detergent and has antimicrobial properties. Moreover, it does not have toxic effects on oral tissues 2,9,[18][19][20]  which is a vegetable native to the Middle East and the northeastern Africa, but is commonly found in tropical climate areas such as Brazil 11,20 . The presence of a hydroxyl group, a single point of unsaturation and a carboxyl group -three highly reactive functional groups in the ricinoleic acid present in the castor oil composition -give R. communis important oilchemical potential. It may be subjected to various chemical processes to obtain by-products used in the pharmaceutical and cosmetic industry, in the production of lubricants, polymers, biodiesel 11

Candidiasis assessment
The palatal mucosa of the participants with candidiasis was photographed with the camera focused on the mid-palatal raphe region, with adequate visualization of the entire region, which includes the incisive papilla until the right and left tuberosity. Images were obtained at baseline after seven days of each intervention and after washout periods. Images were transferred to a computer and the Prosthodontic Tissue Index 5 was applied following scores: "0"(excellent): normal tissue, pink surface, with normal vascularization and appearance; "1" focal hyperemia, but generally normal appearance; "2"    scores at baseline, washout, and after treatments. A change from score "1" (satisfactory) to "0" (absence) and from score "3" (unsatisfactory) to "2" (regular) was found. Table 2 shows the score movement for each solution. S3 and S1 had the highest percentages of the "improved" and "cured", being equal to 50% and 46%, respectively.
Multinomial logistic regression shows that a observed with S3 and S1. The order and sequence of Patients' satisfaction results are show in Table   4. In question 1, the effects of different solutions  For DNA-Checkerboard hybridization results, no differences were found in the amount of total microorganism count between groups with and without candidiasis (p=0.75; Figure 4) or in the interaction microorganisms counts were similar after use of S1, S2, and S3 solutions and lower than S4 ( Figure 5).      had also the same effect as S2 against P. anaerobius and C. dublinienses; S3 was more effective than S1 and S2 against P. aeruginosa. Against other microorganisms such as C. tropicalis, C. krusei, E. coli, and S. mutans, S3 showed results that were mild, less effective than both concentrations of hypochlorite but more effective than saline. It is noteworthy that no difference between treatments was found in the Patients with and without denture stomatitis participated in this study in order to determine whether the analyzed solutions can be used for cleaning of dentures giving preventive and curative actions against candidiasis.

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Results of the questionnaire showed that S1, S2, and S3 had similar patient approval than saline, rejecting the second null hypothesis. This demonstrates that the use of these solutions did not cause any inconvenience to participants, which would prostheses home care. However, this is in contrast with some studies that emphasize malodor and unpleasant taste of NaClO as one of its disadvantages.
Finally, this study reinforces that 10% R. communis and 0.25% NaClO solutions can be used as denture