Ghani F and colleages²⁰ did a study on 50 denture wearers and 50 non denture wearers assessing candida activity through recording pH changes in candida selective medium. Results showed pathological candida activity was significantly higher in denture wearers.

While in a study by Yilmaz HH⁷⁸ 27 patients with denture stomatitis and 23 patients without clinical signs of denture stomatitis were compared. They found that there was a relationship between poor denture hygiene and denture stomatitis and the relationship between denture stomatitis and candidal hyphae was not significant. Therefore proper hygiene is important to prevent denture stomatitis and antifungal drugs should not be prescribed without mycological investigation.

Opportunistic growth of pathogenic yeasts such as candida is promoted by constant denture wearing which maintains anaerobic and low pH conditions between the denture and mucosa.^18. It was revealed in different studies that nearly one third of the patients evaluated slept with their dentures ^19,22,89.

Similarly other studies have found significant association between denture related stomatitis with denture age and continuous denture wearing⁸⁸ moreover candida albicans hyphae and lactobacillus was also found in the saliva and palate of denture stomatitis patients⁸⁹

SURFACE TEXTURE AND PERMEABILITY OF DENTURE BASE:

Highly polished surfaces are important not only for aesthetics and patient’s comfort but also for low plaque adherence, oral hygiene and denture longevity⁸⁴.

In an in vitro study Van Reenen⁷⁹ demonstrated that penetration of the unpolished surface which is in contact with the mucosa with candida albicans was greater than that of polished surface. It was confirmed further with the use of fluorescent dye.

Another study¹⁸ confirmed that surface roughness and cracks facilitate development of biofilm and adherence of plaque.

The authors also noted that prolonged brushing of acrylic denture with toothbrush and abrasive dentrifices create scratches that can enhance bacterial attachment and biofilm growth²².

DENTURE LINING MATERIALS AND ADHESIVES:

In a study by Sato Y and colleagues⁹⁰ it was found that denture adhesives enhance retention and stability of both ill fitting and well fitting dentures.

AL et al ⁹¹ suggested that denture adhesives contribute to mucosal inflammation in denture wearers as they are commonly used throughout the day.

While in an assessment of 24 denture wearing patients Oliveira and colleagues⁹² evaluated the number of colony forming units(CFUs) and Candida species in saliva samples which were collected at denture placement, 7 day and 14 day intervals from patients using an adhesive denture strip. 12 patients using the adhesive were compared with 12 patients not using the adhesive. There was no statistical difference between the groups at the 2 weeks analysis.

MANAGEMENT OF DENTURE STOMATITIS:

Placebo-controlled studies reported that treatment with either oral fluconazole (50mg/day for 2 weeks) or topical miconazole (2% gel applied to fitting surface of the denture 3 times daily for 2 weeks) significantly reduced the presence of candida on oral mucosa and decreased inflammation in denture stomatitis⁹³ .

Cross LJ et al⁹⁴ reported capsule and liquid formulations of itraconazole ( 100 mg 4 times a day for 15 days), fluconazole alone ( 50 mg orally for 14 days) or in combination with chlorhexidine applied to fitting surface of the denture 2 times

a day for 2 weeks and amphotericin ( 40mg oral dissolving lozenges 4 times daily and topical cream applied to fitting surface of denture) all to be effective in the treatment of denture stomatitis.

In a study by Mililla L et al⁹⁵ amorophiline antifungal varnish was applied once or twice a week for 6 months in patients affected by nystatin resistant denture stomatitis. Results showed significant decrease in candidal count and improvement in symptoms of denture stomatitis.

In a study photodynamic therapy was found to be an effective method for resolving candida spp. on dentures⁹⁶

In a study by Webb et al⁹⁷ nursing home patients with denture stomatitis were randomized to maintain their usual hygiene procedures or had their dentures cleaned daily with overnight soaking in sodium hypochlorite and microwaving. Relative to control group both cleaning techniques showed 100% reduction in candida colonization and clinical improvement in denture stomatitis.

In another study 10% vinegar solution was used for the immersion of dentures and was found to be effective in decreasing the quantity of candida spp in saliva and the presence of denture stomatitis ⁹⁸ .

Cryosurgery is the treatment of choice in patients with Type III denture stomatitis along with prosthesis substitution^34.

POST INSERTION INSTRUCTIONS REGARDING MAINTENANCE OF THE PROSTHESIS:

To decrease the levels of biofilm and harmful micro organisms , patients who wear dentures must do the following:

• Dentures must be immersed and brushed with an effective and non abrasive denture cleanser everyday^18.
• Denture cleanser must only be used to clean dentures outside the mouth⁶².
• Dentures must be rinsed thoroughly after immersion and brushing with denture cleansing solution before reinsertion in the oral cavity¹⁶.
• Dentures should be cleaned annually by a dentist using ultrasonic cleanser to minimize biofilm coverage overtime²⁷.
• Dentures must never be placed in boiling water⁷⁷.
• Dentures must never be soaked in sodium hypochlorite bleach for periods greater than 10 minutes because it may damage the dentures²⁸.
• Dentures should be immersed in water after cleaning, when not inserted in oral cavity to avoid warping^16.

MECHANICAL METHODS OF DENTURE CLEANING:

Brushing with tooth brush, denture brush and pastes:

Scanning electron microscopic images and microbiologic essays have demonstrated that cleaning the dentures with water and tooth brushes is ineffective at removing microorganisms^62.

While in a study by Nishi Y and colleagues ²⁵ it was found that the quantity of micro organisms was significantly reduced in the outpatients who used a denture brush for cleaning the prosthesis.

Salles AES and Macedo LD⁹⁹ found in a study that brushing with a denture paste|(Corega Brite) was the most effective method of disinfecting dentures followed by brushing with neutral soap and brushing with water only was the least effective method.

It was found by Lira AF et al¹⁰⁰ that tooth brushing promoted higher levels of surface roughness when compared to chemical disinfection while boiled resins were found to be more prone to surface roughness and biofilm accumulation than microwaved resins.

Pisani MX and Bruhn JP et al¹⁰¹ analyzed surface roughness and weight loss in acrylic caused by dentrifices. They found that the conventional dentrifice containing sodium bicarbonate produced greatest weight loss and surface roughness while dentrifices containing chloramine T and fluorosurfactant produced less weight loss and surface roughness.

While in another study it was found that dentrifices containing 1% chloramine T and 0.01% fluorosurfactant decreased biofilm coverage but were ineffective against candida^102.

Ultrasonic cleaning:

Ultrasonic devices are helpful in removing the plaque adhering to dentures by producing microscopic cavities that grow and burst creating voids that result in localized areas of suction ^16.

Gwinnet et al¹⁰³ showed in different ways effective disinfection of inoculated dentures using ultrasonic treatment in a water bath as well as in various baths of antiseptic and detergent agents.

In another study it was found that ultrasonic cleaning when combined with immersion in a peroxide based cleanser solution effectively reduces the quantity of micro organisms surviving on dentures²⁵. Hence may be a suitable method for elderly who find brushing their dentures difficult.

Studies have found that ultrasonic cleaning is not completely bactericidal but improves the killing of bacteria^16.

Chemical Methods:

Soaking in household solution:

Sodium hypochlorite diluted 1:10 in tap water is adequate for killing adherent micro organisms but is ineffective against calculus buildup and stains. Metallic elements in the denture acquire a black stain after soaking in bleach for greater than 10 minutes daily⁶²

In a study done by Dr. Roshan Khan 5.25% sodium hypochlorite was more effective in disinfecting dentures as compared to 0.2% chlorhexidine at a 5 minute immersion period^28.

Surface roughness was evaluated by Paranhos HDO et al⁶⁴ and they found that immersing the acrylic resin denture in 0.5% sodium hypochlorite solution every night for more than a year and a half resulted in increased surface roughness while no effect was noted regarding the flexural strength of the acrylic.

A major issue in immuno compromised and hospitalized patients is the emergence of methicillin resistant staphylococcus aureus(MRSA) which increases mortality rates significantly ^16.

Lee and colleagues¹⁰⁴ showed that MRSA can be killed effectively with sodium hypochlorite.

The use of vinegar (acetic acid) was evaluated by Basson et al¹⁰⁵ and they found it effective at killing adherent micro organisms albeit less effective than sodium hypochlorite. Vinegar has an advantage over bleach and it is that inadequate rinsing after soaking in vinegar does not result in mucosal damage.

In another study vinegar alone is found to be least effective at removing denture plaque but when used in combination with brushing its results were comparable with those of denture cleansers²⁴

Soaking in a commercial solution:

Immersing the dentures in denture cleansers reduces the micro organisms and plaque and is found to be a suitable method for denture cleansing specially for geriatric patients^106.

It was found that soaking in alkaline peroxide every night for more than a year resulted in color alteration of the resin^64.

In a study it was found that the combination of brushing and peroxide cleansers was the most efficacious method to remove denture plaque^24.

It was found in a study by de Andrade IM and colleagues¹⁰⁷ that the effervescent tablets are effective in reducing streptococci mutans and total aerobes from denture biofilm. However, they were not as effective against C. albicans

Mc Cabe and colleagues¹⁰⁸ reported that effects of alkaline peroxide solution were enhanced using water at a temperature of 50 centigrade.

In a study done to investigate the relationship between the frequency of use of denture cleanser and the quantity of micro organisms adhering to dentures it was found that patients who used denture cleansers daily or 3-4 times a week had significantly lower amount of micro organisms than the patients who used the denture cleanser once or less per month^25.

While in a study by Jose A and colleagues²³ it was concluded that denture cleansers were effective against Candida albicans activity both in terms of removal and disinfection but residual biofilm retention that could lead to re growth and denture colonization was seen. Hence alternate mechanical cleaning methods are required to enhance biofilm removal.^.

New materials for denture immersion contain silicon polymer that provides a protective coating on denture as a final step in cleaning process. Coating helps to minimize adhesion of debris throughout the day until the next cleaning^27.

MICROWAVE RADIATION

Effectiveness of microwaving depends on solution in which the dentures are immersed, the time of exposure, the level of power of microwave oven and the types of micro organisms adhering the denture¹⁰⁹.

Senno P and colleagues¹¹⁰ found that putting the dentures in denture cleanser and then microwaving was efficient in disinfecting dentures with lower irradiation time and temperature than the use of microwave irradiation alone therefore avoiding denture distortion. While in another study it was concluded that immersing the denture in a cup of water to transfer heat uniformly during microwave sterilization was more effective¹¹¹.

While Kaskin et al¹¹² showed that independent of solution used irradiation for 15 minutes at 500 watt achieved complete sterilization of acrylic resin base materials contaminated by Staphylococcus aureus, Escherichia coli, candida albicans and streptococcus mutans.

It was concluded by Brondani MA et al¹⁰⁹ that irradiation time above 15minutes and voltage greater than 850 watts may cause distortion and surface roughness of the denture while not affecting the hardness of the material.

While in another study 50 seconds of exposure at 850 watt seemed to be sufficient to disinfect the acrylic denture without any adverse effect on the material^113.

ALTERNATE DENTURE CLEANSING METHODS:

Chlorhexidine destroys bacteria by breaking their membranes and inducing cytoplasmic precipitation^114.

In a study by de Andrade IM and colleagues ¹⁰⁷ 60 CD wearers participated in a trial for 21 days after getting brushing instructions. They found that the biofilm coverage area after treatment with immersion in 2% chlorhexidine for 5 minutes was the lowest when compared to immersion in water and in 0.12% chlorhexdine for 20 minutes.

While in a study by Uludamar A and colleagues²⁶ it was found that patients whose upper dentures were sprayed with mouthwashes on palatal surface showed decreased candida count when compared to patients who used effervescent type denture cleansers for soaking and cleaning. It can be concluded that mouthwashes can be used as effective denture disinfectants.

Tissue cleansing and massage is often neglected part of complete denture care. Brushing the tongue and residual ridges will improve the circulation and remove plaque and debris that may cause irritation of soft tissue and offensive odors ^115. In a study by Marchini L¹¹⁶ it was found that 68% of the complete denture wearers didn’t clean their tongue.

PERIODIC RECALL FOR ORAL EXAMINATION:

Patient recall must be a tool to help prevention, allow early intervention and ensure long term dental health¹¹⁷. In a study by Peracini A 51`% of the patients interviewed were not informed about their recall visits.¹¹⁸ An evidence based, patient centered approach taking into account multiple risk categories must be implemented in designing recall visits.¹¹⁹

The American College of Prosthodontists recommends that patients wearing complete dentures must be checked every year for assessment of oral health status, denture fit and function and for evaluation of bone loss as well as oral lesions such as denture stomatitis ¹⁶. This recommendation is based on the evidence regarding the relationship between proper complete denture oral hygiene and overall systemic health particularly in dependant elderly^45.