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156 rev port estomatol med dent cir maxilofac. 2019;60(4):155-162

Propriedades de superfície após envelhecimento químico de sistemas
de libertação de clorexidina à base de resina acrílica

r e s u m o

Palavras-chave: Objetivos: Avaliar o efeito da incorporação de clorexidina na energia de superfície e resistên-
Resinas acrílicas cia adesiva à microtração de três resinas acrílicas de rebasamento, após envelhecimento
Clorexidina químico.
Estomatite protética Métodos: Para cada um dos estudos foram criados 6 grupos experimentais de acordo com
Tensão superficial resina de rebasamento e incorporação de clorexidina (Kooliner – 0% vs. 2,5%; Ufi Gel Hard e
Resistência à tração Probase Cold – 0% vs. 5%). Os espécimes foram submetidos a um processo de envelhecimen-
to químico durante 4 semanas (variações de pH em saliva artificial, com ciclos de 6 horas
em pH=3 e 18 horas em pH=7). Para o primeiro estudo foram preparados 42 espécimes (n=7)
e após envelhecimento químico foi calculada a energia de superfície. Para determinação
da resistência adesiva, foram preparados 36 cubos de Probase Hot e sobre estes aplicada a
resina de rebasamento de acordo com o grupo experimental (n=6). Obtidos 5 palitos (secção
1×1 mm) de cada espécime, foram sujeitos a envelhecimento químico, seguido de teste de
microtração (1 kN; 1 mm/min). Os dados foram avaliados estatisticamente com testes
não-paramétricos segundo Kruskal-Wallis e Mann-Whitney (α=0,05).
Resultados: Observaram-se diferenças (p<0,05) entre as resinas, tanto na energia de superfí-
cie como na resistência adesiva. A energia de superfície de nenhuma das resinas foi afetada
pela incorporação de clorexidina, que também não afetou a resistência adesiva de Kooliner
e de Ufi Gel Hard (p>0,05). Incorporar 5% de clorexidina reduziu significativamente (p=0,004)
a resistência adesiva de Probase Cold.
Conclusões: Após envelhecimento químico, a incorporação de clorexidina apenas afetou
negativamente a resistência adesiva de Probase Cold. (Rev Port Estomatol Med Dent Cir Ma-
xilofac. 2019;60(4):155-162)
© 2019 Sociedade Portuguesa de Estomatologia e Medicina Dentária.
Published by SPEMD. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).

of the therapeutic dosage of the drugs is very dependent on
Introduction
complex regimes of patient compliance. Also, antifungal ther-
The physiologic progression of a residual ridge resorption can apy does not provide the complete eradication of the microor-
affect the adaptation and retention of a denture base and lead ganisms from the dentures surface. 16-19 Chlorhexidine (CHX),
to loss of masticatory efficiency and comfort, as well as possi- an antimicrobial agent that acts against a wide range of mi-
ble trauma of the underlying tissues. In order to avoid den- croorganisms, including Candida species, is another possible
1,2
ture rejection, periodic examination of the denture and under- therapy. 14-17 However, its efficiency in topical solutions de-
lying support tissues is advised to detect these changes and, if pends on the turnover of saliva and the cleansing action of the
necessary, a relining procedure should be performed. 3,4 oral musculature. 14,20 In order to increase the availability of the
Denture stomatitis is a highly prevalent chronic condition, agent in the target area at a therapeutic dosage, loading reline
usually asymptomatic, that manifests as a diffuse inflamma- acrylic resins with CHX has been proposed as a therapeutic
tion of the mucosa in contact with the denture. 5-8 Despite the approach for denture stomatitis, to allow a slow and sustained
evidence of fungal etiology, several factors have been suggest- releasing for at least 28 days, with a more effective antifungal
9
ed in a multifactorial etiology. Even though other Candida spe- activity than other drugs. 14-18,21,22
cies may contribute to this disease, Candida albicans is the main Reline acrylic resins may have different chemical compo-
causative agent, and its adherence to the oral mucosa and the sitions and structural arrangements. Kooliner and Ufi Gel Hard,
denture surface is considered the first step in the pathogene- a non-crosslinking and a crosslinking relining material, respec-
sis of denture stomatitis. 9 tively, are both poly(ethyl methacrylate)-based resins and are
Treatment usually involves topical or systemic antifungal used in a direct technique, being polymerized in the mouth. On
therapy, good oral hygiene, denture cleaning procedures, ad- the other hand, Probase Cold, which is a poly(methyl methac-
justment of denture failures, discontinuation of night-time rylate)-based reline material, is used in an indirect technique,
denture wear, nutritional restitution and relining or replacing being polymerized under laboratory conditions. 23,24
of the denture. 7,10-17 Topical and systemic antifungal therapy The incorporation of CHX into polymeric materials may af-
is commonly applied, in spite of contributing to highly fre- fect their mechanical and surface properties. A CHX concentra-
25
quent relapse episodes of the disease, since the maintenance tion of 2.5% for Kooliner and 5% for both Ufi Gel Hard and Probase