Evaluating the effect of soft lining materials on the growth of yeast.
BACKGROUND
Soft lining materials continue to have a place in clinical removable prosthodontics. However, there is an increased probability of yeast colonization on soft lining materials.


OBJECTIVE
This study (1) assessed a method of evaluating the effect of long-term soft lining materials on the growth of yeast and (2) investigated the effect five soft lining materials had on the growth of three species of yeast.


METHODS
Coe Supersoft, Novus, and three experimental soft lining materials were investigated together with Candida albicans, Candida tropicalis, and Issatchenkia orientalis (formerly Candida krusei) yeasts. Strips of soft lining material incubated on blood agar plates were examined for inhibition of the growth of yeast. Soft lining materials soaked in sterile trypticase soya broth or water were inoculated with yeast and incubated. The change in colony forming units per milliliter from the initial load of yeast at 3 days was measured. Statistical analysis was performed with an independent paired Student t test.


RESULTS
Inhibition of yeast growth occurred for two soft lining materials. Despite the presence of sufficient viable organisms, differences between the initial load of yeast and the 3-day results were mostly small, both for the test and control groups, suggesting that the material does not support the growth of the tested yeast during this period.


CONCLUSIONS
The often described increased prevalence of yeast associated with soft lining materials in the oral environment is likely related to readily available nutrients in the mouth and the difficulty in maintaining and cleaning these materials.
Wright
P S
PS
Department of Prosthetic Dentistry, St. Bartholomew's and the Royal London School of Medicine and Dentistry, England, United Kingdom.
Young
K A
KA
Riggs
P D
PD
Parker
S
S
Kalachandra
S
S
D000180:Acrylic Resins / Q000737:chemistry; D000327:Adsorption; D000890:Anti-Infective Agents / Q000494:pharmacology; D002175:Candida / Q000145:classification / Q000254:growth & development*; D002176:Candida albicans / Q000254:growth & development; D015169:Colony Count, Microbial; D003822:Denture Liners / Q000382:microbiology*; D005069:Evaluation Studies as Topic; D005500:Follow-Up Studies; D006801:Humans; D008422:Materials Testing; D009055:Mouth / Q000382:microbiology; D009943:Organophosphorus Compounds / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D015995:Prevalence
D000180:Acrylic Resins; D000890:Anti-Infective Agents; D009943:Organophosphorus Compounds; D011108:Polymers; C076789:polyphosphazene fluoroelastomer; C076423:Coe Super-Soft