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Fungus growth on tissue conditioners and soft denture liners
A study was made to determine whether silicone and methacrylate soft liners and tissue conditioners would sustain the growth of Candida albicans in vitro. Although both of these materials have the potential for supporting growth of C. albicans, tissue conditioners seldom remain in the patient's mouth long enough for yeast organisms to grow. Whereas sufficient amounts of zinc undecylenate eliminate fungal growth, its long-term effectiveness has not yet been tested.
Fungus growth on tissue conditioners and soft denture liners
Rolf G. Gruber, MS, DDS Frank M . Lucatorto, MS, DDS Eugene J. Molnor, DDS, M D , Chicago
Two materials growing in popularity with the practitioners of prosthetic dentistry are tissue con ditioners and soft denture liners. A s a rule, tissue conditioners are allowed to remain in place for a reasonably short time, measured in days, where as soft liners are worn for more extended periods. It has been observed by us that sometimes when patients have been wearing dentures with the soft silicone lining material, small, whitish elevations of fungal growth appear on the surface of this material (Fig. 1 ). On microscopic examin ation, these were found to be primarily Candida albicans. This phenomenon has previously been reported by Gibbons.1 The presence of colonies of C. albicans in the oral cavity cannot be ignored. In adults, infection with C. albicans usually follows a debilitating illness. Chronic oral lesions may last several years. Occasionally, the fungus spreads to the skin and gastrointestinal tract to produce a generalized moniliasis.2
Although C. albicans (Monilia albicans) is con sidered to be the only true pathogenic member of the genus, several cases of mycotic endocarditis have been reported from which Candida parakrusei and Candida guilliermondi have been cultured.3 Prolonged use of antibiotics seems to enhance the growth of the fungus.4 This is a preliminary report of the ability of the silicone and methacrylate Soft liners and the tissue conditioners to sustain the growth of C. albicans in vitro. The evaluated materials and results, using a minimum of four tests, are shown in Table 1 and Table 2.
Procedure Specimens were made according to manu facturers’ directions and stored in distilled water for 72 hours. A ll instruments and containers were aseptically clean, and every effort was made to avoid contamination. The prepared pieces were placed in sterile petri dishes and bathed in nutrient broth (D ifco ). Each of these were then properly inoculated with pure stock cultures of C. albicans and incubated at 2 5 °C. for 5 days. Periodic examination for evi dence of growth on the surface of these pieces revealed growths starting to show on the third day of incubation. Typical whitish C. albicans colonies were attached to the surface and their 641
Fig. i ■ Fungal growth of Candida albicans on surface of silicone soft liner without fungicide
presence substantiated by microscopic examina tion. In an attempt to eliminate fungal growth on the silicone liners, two different fungicides were used. One set of specimens were immersed in a liquid fungicide*5-8 for 72 hours and removed and stored in distilled water for 24 hours. These specimens were then cultured. Second, 0.5 percent and 1.5 percent (by weight) of zinc undecylenate were incorporated into the silicone mass before processing the liners.714. These were also cultured. Zinc undec ylenate, which is one of the commonly used fungicides, was used because of its relative water insolubility, fine particle size, and compatibility with the tissue conditioning and soft liner materials. In addition, two relining materials in sheet form of the type described by Woelfel and others15 were cultured. These are materials that may be purchased in drugstores and supermarkets. These materials were cultured, and, in all in stances, they supported the growth of fungus.
R e s u lt s
Fig. 2 ■ Absence of growth of Candida albicans on surface of silicone soft liner with 1.5 percent (by weight) of zinc undecylenate
As indicated in Table 1, in the absence of a fungicide of sufficient concentration, all of the silicone liners were able to support growth of C. albicans (specimen 1, 2, and 4 ). Conversely, the silicone liner did not support fungal growth when zinc undecylenate of sufficient concentration was introduced into the mass of the the material (specimen 3, Fig. 2 ). The concentration of zinc undecylenate of less than 1.5 percent (by weight and soaking the material in a liquid fungicide (M icrocide-B) were both ineffective in preventing growth of fungus (specimens 2, 4 ). Both the heat-cured and the cold-cured liners Table 1 ■ Presence of Candida albicans growth on soft re liners Specimen
1 2 3
Fig. 3 ■ Fungal growth of Candida albicans on surface of tissue conditioner without fungicide
642 ■ JAD A, Vol. 73, Sept. 1966
4 5 6 7
Material Silicone liner (as supplied by manufacturer) Silicone liner (with 0 .5 % zinc undecyienate) Silicone liner (with 1.5% zinc undecylenate) Silicone liner (with Microcide B) Heat-cured methacrylate liner Cold-cured methacrylate liner Heat-cured denture resin (control)
^Growth = + ; no growth = 0.
Growth*
+ + 0
+ Ö 0 0
Table 2 ■ Presence of Candida albicans growth on tis sue conditioners
1 2 3 4
Growth*
Material
Specimen
Tissue conditioner (A) (with 1.0% zinc undecylenate as supplied by manufacturer) Tissue conditioner (A) f Tissue conditioner (B) (as supplied by manufacturer) Tissue conditioner (C) (as supplied by manufactured)
0
tion, the effectiveness of other fungicides, such as derivatives of caprylic and propionic acid, when used in conjunction with these lining materials, will be investigated.
+ + +
^Growth = + ; no growth = 0. fCompounded without zinc undecylenate (not commercially available).
containing methacrylate monomers did not sup port fungal growth in vitro. In no instance did the heat-cured acrylic denture resin that was used as a control show evidence of growth. As shown in Table 2, all of the tissue condi tioners were able to support fungal growth in the absence of a fungicide.
Discussion It seems evident that both tissue conditioners and the silicone soft lining material have the potential for supporting growth of C. albicans. One might speculate that the reason there are no clinical reports of this occurring with the tissue conditioners is that, as a rule, they are not allowed to remain in the patient’s mouth for a sufficiently long period. This is not the situation with the soft silicone liners, and such Clinical reports have been presented. This in vitro study also indicates that the in corporation of sufficient amounts of zinc undecyleiiate effectively eliminates the potential of these materials to support the growth of these yeast organisms. Other than the fact that materials that contain monomeric methyl methacrylate as one of the com ponents of the liquid do not sustain fungal growth, no explanation is given for this phenomenon, investigation of this problem however, is being initiated. In light of the fact that these materials are used either as long-term reliners or a shorter-term treatment material, it seems desirable for the practitioners, or preferably the manufacturers, to introduce an effective, nontoxic fungicide into the materials. Further study is indicated to evaluate the long term effectiveness of zinc undecylenate. In addi
, Doctor Gruber is associate professor and chairman of the department of dental materials at Loyola University School of Dentistry, 1757 W est Harrison Street^ Chicago, 60$12. Doctor Lucatorto is presently associate clinical professor of oral medicine, University of Southern C ali fornia School of Dentistry, Los Angeles; formerly, associate professor and chairman of the oral diagnosis department, Loyola University School of Dentistry, Chicago. Doctor M olnar is associate professor of dental materials, Loyola University School of Dentistry, Chicago. *Microcide-B. Composition is 5.0 percent para-amino toluine sulfonamide, 0.08 percent nitromethylfurfuryl e th e r. in an aqueous solution, 91.92 percent HaO, and 3.0 percent ethyl alcohol by weight. 1. Gibbons, P. Clinical and bacteriological, findings in patients wearing silastic 390 soft liner. J Mich Dent Assn 47:65 March, 1965. 2. Dubos René Jules (ed .). Bacterial and mycotic infections of man, ed. 2. Philadelphia, J. B. Lippincott Co., 1952, p. 663. 3. Dubos, René Jules (ed .). Bacterial and mycotic infections of man, ed. 2. Philadelphia, J . B. Lippincott Co., 1952, p. 664. 4. M . Lacaisse, and others. Aspects actuels des candidoses. Rev Stomat 64:670 Feb., 1963. 5. Gurney, B. F., and Best, E. J. A new and superior endodontic bactericidal agent. Part I. Oral Surg 12:104 Jan., 1959. 6. Best, E. J.; Gurney, B. F., and Conlin, A. A new and superior endodontic bactericidal. Part II. Oral Surg .12:222 Feb., 1959. 7. M erck Index, ed. 7. Rahway, N. J., M erck and Co., 1960, p. 1079-1080. 8. Keeney, E. L. Sodium caprylate; new and effective treatment for moniliasis of skin and mucous membranes. Bull Hopkins Hosp 78:333 June, 1946. 9. Sulzberger, M . B.; Shaw, H. C., and Kanof, A. Evaluation of measures for use against common fungous infections of skin; screening tests by means of paired com parisons on human subjects. U S N av Med Bull 45:237 Aug., 1945. 10. Shapiro, A. L., and Rothmaf^, S. Undecylenic acid in the treatment of dermatamycosis. Arch Derm 52:166 Sept., 1945. 1 1. Carrick, Lee. Methods of Iqc&I therapy for tinea capitis dué to Microsporon audouini. J A M A 131:1189 Aug. 10, 1946. . 12. Peck, S. M., and Rosenfeld, H. Effects of hydrogen ion concentration, fatty ocids, and vitamin C on growth of fungi.. J Invest Derm 1 :237 Aug., 1938. 13. Lesser, M . A. Newer fungicidal products. Drug Cosmet Industr 69:468 April, 1951. 14. Talice, R. J. Le facteur pH en mycologie; son influence sur la culture de certaines espèces de cham pignons parasites de l'homme. Ann Parasit Hum Comp 8:183 M arch 1, 1930. 15. W oelfel, J. B., and others. Documented reports of bone loss caused by use of a denture reliner. JA D A 71 :23 July, 1965.
Gruber-Lucatorto-Molnar: FU N G U S G R O W T H ON T IS S U E C O N D IT IO N E R S ■ 643
Fungus growth on tissue conditioners and soft denture liners
Rolf G. Gruber, MS, DDS Frank M . Lucatorto, MS, DDS Eugene J. Molnor, DDS, M D , Chicago
Two materials growing in popularity with the practitioners of prosthetic dentistry are tissue con ditioners and soft denture liners. A s a rule, tissue conditioners are allowed to remain in place for a reasonably short time, measured in days, where as soft liners are worn for more extended periods. It has been observed by us that sometimes when patients have been wearing dentures with the soft silicone lining material, small, whitish elevations of fungal growth appear on the surface of this material (Fig. 1 ). On microscopic examin ation, these were found to be primarily Candida albicans. This phenomenon has previously been reported by Gibbons.1 The presence of colonies of C. albicans in the oral cavity cannot be ignored. In adults, infection with C. albicans usually follows a debilitating illness. Chronic oral lesions may last several years. Occasionally, the fungus spreads to the skin and gastrointestinal tract to produce a generalized moniliasis.2
Although C. albicans (Monilia albicans) is con sidered to be the only true pathogenic member of the genus, several cases of mycotic endocarditis have been reported from which Candida parakrusei and Candida guilliermondi have been cultured.3 Prolonged use of antibiotics seems to enhance the growth of the fungus.4 This is a preliminary report of the ability of the silicone and methacrylate Soft liners and the tissue conditioners to sustain the growth of C. albicans in vitro. The evaluated materials and results, using a minimum of four tests, are shown in Table 1 and Table 2.
Procedure Specimens were made according to manu facturers’ directions and stored in distilled water for 72 hours. A ll instruments and containers were aseptically clean, and every effort was made to avoid contamination. The prepared pieces were placed in sterile petri dishes and bathed in nutrient broth (D ifco ). Each of these were then properly inoculated with pure stock cultures of C. albicans and incubated at 2 5 °C. for 5 days. Periodic examination for evi dence of growth on the surface of these pieces revealed growths starting to show on the third day of incubation. Typical whitish C. albicans colonies were attached to the surface and their 641
Fig. i ■ Fungal growth of Candida albicans on surface of silicone soft liner without fungicide
presence substantiated by microscopic examina tion. In an attempt to eliminate fungal growth on the silicone liners, two different fungicides were used. One set of specimens were immersed in a liquid fungicide*5-8 for 72 hours and removed and stored in distilled water for 24 hours. These specimens were then cultured. Second, 0.5 percent and 1.5 percent (by weight) of zinc undecylenate were incorporated into the silicone mass before processing the liners.714. These were also cultured. Zinc undec ylenate, which is one of the commonly used fungicides, was used because of its relative water insolubility, fine particle size, and compatibility with the tissue conditioning and soft liner materials. In addition, two relining materials in sheet form of the type described by Woelfel and others15 were cultured. These are materials that may be purchased in drugstores and supermarkets. These materials were cultured, and, in all in stances, they supported the growth of fungus.
R e s u lt s
Fig. 2 ■ Absence of growth of Candida albicans on surface of silicone soft liner with 1.5 percent (by weight) of zinc undecylenate
As indicated in Table 1, in the absence of a fungicide of sufficient concentration, all of the silicone liners were able to support growth of C. albicans (specimen 1, 2, and 4 ). Conversely, the silicone liner did not support fungal growth when zinc undecylenate of sufficient concentration was introduced into the mass of the the material (specimen 3, Fig. 2 ). The concentration of zinc undecylenate of less than 1.5 percent (by weight and soaking the material in a liquid fungicide (M icrocide-B) were both ineffective in preventing growth of fungus (specimens 2, 4 ). Both the heat-cured and the cold-cured liners Table 1 ■ Presence of Candida albicans growth on soft re liners Specimen
1 2 3
Fig. 3 ■ Fungal growth of Candida albicans on surface of tissue conditioner without fungicide
642 ■ JAD A, Vol. 73, Sept. 1966
4 5 6 7
Material Silicone liner (as supplied by manufacturer) Silicone liner (with 0 .5 % zinc undecyienate) Silicone liner (with 1.5% zinc undecylenate) Silicone liner (with Microcide B) Heat-cured methacrylate liner Cold-cured methacrylate liner Heat-cured denture resin (control)
^Growth = + ; no growth = 0.
Growth*
+ + 0
+ Ö 0 0
Table 2 ■ Presence of Candida albicans growth on tis sue conditioners
1 2 3 4
Growth*
Material
Specimen
Tissue conditioner (A) (with 1.0% zinc undecylenate as supplied by manufacturer) Tissue conditioner (A) f Tissue conditioner (B) (as supplied by manufacturer) Tissue conditioner (C) (as supplied by manufactured)
0
tion, the effectiveness of other fungicides, such as derivatives of caprylic and propionic acid, when used in conjunction with these lining materials, will be investigated.
+ + +
^Growth = + ; no growth = 0. fCompounded without zinc undecylenate (not commercially available).
containing methacrylate monomers did not sup port fungal growth in vitro. In no instance did the heat-cured acrylic denture resin that was used as a control show evidence of growth. As shown in Table 2, all of the tissue condi tioners were able to support fungal growth in the absence of a fungicide.
Discussion It seems evident that both tissue conditioners and the silicone soft lining material have the potential for supporting growth of C. albicans. One might speculate that the reason there are no clinical reports of this occurring with the tissue conditioners is that, as a rule, they are not allowed to remain in the patient’s mouth for a sufficiently long period. This is not the situation with the soft silicone liners, and such Clinical reports have been presented. This in vitro study also indicates that the in corporation of sufficient amounts of zinc undecyleiiate effectively eliminates the potential of these materials to support the growth of these yeast organisms. Other than the fact that materials that contain monomeric methyl methacrylate as one of the com ponents of the liquid do not sustain fungal growth, no explanation is given for this phenomenon, investigation of this problem however, is being initiated. In light of the fact that these materials are used either as long-term reliners or a shorter-term treatment material, it seems desirable for the practitioners, or preferably the manufacturers, to introduce an effective, nontoxic fungicide into the materials. Further study is indicated to evaluate the long term effectiveness of zinc undecylenate. In addi
, Doctor Gruber is associate professor and chairman of the department of dental materials at Loyola University School of Dentistry, 1757 W est Harrison Street^ Chicago, 60$12. Doctor Lucatorto is presently associate clinical professor of oral medicine, University of Southern C ali fornia School of Dentistry, Los Angeles; formerly, associate professor and chairman of the oral diagnosis department, Loyola University School of Dentistry, Chicago. Doctor M olnar is associate professor of dental materials, Loyola University School of Dentistry, Chicago. *Microcide-B. Composition is 5.0 percent para-amino toluine sulfonamide, 0.08 percent nitromethylfurfuryl e th e r. in an aqueous solution, 91.92 percent HaO, and 3.0 percent ethyl alcohol by weight. 1. Gibbons, P. Clinical and bacteriological, findings in patients wearing silastic 390 soft liner. J Mich Dent Assn 47:65 March, 1965. 2. Dubos René Jules (ed .). Bacterial and mycotic infections of man, ed. 2. Philadelphia, J. B. Lippincott Co., 1952, p. 663. 3. Dubos, René Jules (ed .). Bacterial and mycotic infections of man, ed. 2. Philadelphia, J . B. Lippincott Co., 1952, p. 664. 4. M . Lacaisse, and others. Aspects actuels des candidoses. Rev Stomat 64:670 Feb., 1963. 5. Gurney, B. F., and Best, E. J. A new and superior endodontic bactericidal agent. Part I. Oral Surg 12:104 Jan., 1959. 6. Best, E. J.; Gurney, B. F., and Conlin, A. A new and superior endodontic bactericidal. Part II. Oral Surg .12:222 Feb., 1959. 7. M erck Index, ed. 7. Rahway, N. J., M erck and Co., 1960, p. 1079-1080. 8. Keeney, E. L. Sodium caprylate; new and effective treatment for moniliasis of skin and mucous membranes. Bull Hopkins Hosp 78:333 June, 1946. 9. Sulzberger, M . B.; Shaw, H. C., and Kanof, A. Evaluation of measures for use against common fungous infections of skin; screening tests by means of paired com parisons on human subjects. U S N av Med Bull 45:237 Aug., 1945. 10. Shapiro, A. L., and Rothmaf^, S. Undecylenic acid in the treatment of dermatamycosis. Arch Derm 52:166 Sept., 1945. 1 1. Carrick, Lee. Methods of Iqc&I therapy for tinea capitis dué to Microsporon audouini. J A M A 131:1189 Aug. 10, 1946. . 12. Peck, S. M., and Rosenfeld, H. Effects of hydrogen ion concentration, fatty ocids, and vitamin C on growth of fungi.. J Invest Derm 1 :237 Aug., 1938. 13. Lesser, M . A. Newer fungicidal products. Drug Cosmet Industr 69:468 April, 1951. 14. Talice, R. J. Le facteur pH en mycologie; son influence sur la culture de certaines espèces de cham pignons parasites de l'homme. Ann Parasit Hum Comp 8:183 M arch 1, 1930. 15. W oelfel, J. B., and others. Documented reports of bone loss caused by use of a denture reliner. JA D A 71 :23 July, 1965.
Gruber-Lucatorto-Molnar: FU N G U S G R O W T H ON T IS S U E C O N D IT IO N E R S ■ 643