BackgroundThe aim of this study was to clarify the mechanism behind the different erosive potential of regular and light cola drinks: pH difference and/or aspartame presence.Material and MethodsSixty bovine enamel blocks were randomly divided into 5 groups: RC - regular cola, RCpH - addition of base to increase regular cola pH, RCAS - addition of aspartame to regular cola, LC - light cola, and LCpH - addition of acid to decrease light cola pH. Two-thirds of the blocks surface was coated with nail varnish for reference. The samples were daily subjected to four erosive challenges for 2 minutes. Between the erosive challenges (2h) and overnight the samples were maintained in artificial saliva. The response variable was the percentage surface hardness change (%SHC) after 1st experimental day and enamel surface loss (µm) measured at the 5th day by profilometry. Data were analyzed by ANOVA and Tukey’s test (p<0.05).ResultsIndependently of the cola modifications, all groups promoted similar hardness change of enamel surface. RC promoted higher enamel loss (6.69±0.71µm) than LC (4.80±0.77µm). The acid addition to light cola (LCpH: 6.60±1.78µm) significantly enhanced its erosive potential, which did not differ from RC. The base addition to regular cola (RCpH-4.00±0.64µm) resulted in similar wear to LC. The addition of aspartame to the regular cola (RCAS 5.44±0.65µm) resulted in similar wear to LC and RC.ConclusionsThe data suggest that the pH alteration has a major impact on the erosive potential of cola drinks, however, the sweetener also has some influence. Key words:Tooth erosion, dental enamel, soft drinks, ph, sweetener.

Objetivo:Comparar o potencial erosivo de bebidas light e zero em relação a sua versão regular sobre o esmalte. Método: Blocos de esmalte bovino foram divididos em 7 grupos (n=10) e submetidos à ciclagem erosiva com a versão regular ou light/zero das seguintes bebidas: Coca-cola ® , Guaraná ® e Sprite ® . Antes da imersão, metade da superfície dos blocos de esmalte foi protegida com esmalte cosmético para referência na análise perfilométrica. As imersões nas bebidas de acordo com os grupos em estudo foram realizadas 4 vezes ao dia durante 2 minutos. Entre os desafios erosivos os blocos foram imersos em saliva artificial por 2 horas. A cada dia, após as 4 ciclagens erosivas os blocos foram armazenados em saliva artificial. Ao final do 5º dia de ciclagem a alteração da superfície do esmalte foi analisada por perfilometria (µm). Os dados foram analisados com ANOVA e teste de Tukey (para as bebidas tipo cola) e teste t não pariado (para as outras bebidas) (p<0.05). Resultados: A cola light (0.52±0.19) provocou um desgaste similar a cola zero (0.54±0.17) e ambas causaram menor desgaste quando comparadas a cola regular (2.15±0.65). A sprite regular (1.17±0.36) provocou menor desgaste do que a versão zero (2.25±0.75). Os guaranás regular (1.03±0.36) e light (1.02±0.26) resultaram em desgaste semelhante no esmalte. Conclusão: O presente estudo in vitro constatou que as colas light e zero apresentaram menor potencial erosivo, o que não foi observado para as versões zero da guaraná e da Sprite, as quais causaram desgaste semelhante e maior que a versão regular, respectivamente. Erosão dentária; Desgaste dos dentes; Refrigerantes; Dieta.Objective: To evaluate the erosive potential of light and zero soft drinks compared with the regular version on dental enamel. Method: Bovine enamel slabs were divided into 7 groups (n=10) and subjected to erosive challenge by immersion in the light, zero and regular versions of the following soft drinks: Coca-cola ® , Guaraná ® and Sprite ® . Before immersion in the beverages, half of slab surface was protected with nail varnish for reference for the profilometry analysis. The enamel slabs were immersed in the beverages for 2 minutes, 4 times a day, at room temperature. Between challenges, the slabs were maintained in artificial saliva for 2 hours. Every day after completion of the four pH-cycles, the samples were stored in artificial saliva overnight. At the end of the 5 th day of erosive challenge, the alterations on enamel surface were measured by profilometry (µm). Data were analyzed by ANOVA and Tukey's test (for cola drinks) and unpaired t test (for the other beverages) (p<0.05). Results