pH Changes in Human Dental Plaque from Lactose and Milk before and after Adaptation

Abstract

pH changes in human dental plaque in vivo from lactose and milk have been studied in four separate mouthrinse experiments. (1) pH was measured in plaque samples of 12 subjects before and after 6 weeks of frequent daily mouth-rinsing with 10% lactose. The pH decreases were significantly more pronounced after the adaptation period than before (p < 0.001), 4 of the 12 subjects showing about the same low plaque pH from lactose as from glucose. (2) Similar to the previous experiment, frequent daily mouthrinsing with low-fat bovine milk in 10 subjects resulted in more pronounced pH decreases in plaque after an adaptation period of 4 weeks (p < 0.001). (3) Single mouthrinses, without any prior adaptation, with bovine standard milk, human breast milk, lactose-hydrolysed bovine standard milk, 5% lactose and 5% sucrose were compared regarding the effect on plaque pH in 7 subjects. All solutions resulted in pH falls. The most pronounced were found with sucrose, followed by the lactose-hydrolysed milk. (4) Bovine standard milk, 5% lactose and 10% sucrose were compared after a single mouthrinse in 5 subjects using interdental plaque pH wire telemetry. Lactose and milk were fermented more slowly than sucrose. In a separate study, acid production from lactose was also measured in two oral strains each of Streptococcus mutans, Streptococcus salivarius and Streptococcus sanguis. The results from these experiments indicated that at least part of the lactose transport and catabolism in all studied streptococcus strains seems to be regulated by inducible enzymes.

Breastfeeding and early childhood caries: a critical review

“…Além disso, os estreptococos somente são capazes de aumentar a fermentação da lactose após o contato freqüente com o leite, podendo ser esta, segundo esses autores, uma das razões para o desenvolvimento de cárie em dentes decí-duos pelo aleitamento materno prolongado em livre demanda. Entretanto, para os mesmos autores, o potencial cariogênico do leite, sob condições normais, carece de importância clínica, exceto quando da diminuição dos fatores de defesa salivares, tal como ocorre durante o sono e na presença de xerostomia 57 .…”

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“…However, for the same authors, the cariogenic potential of milk under normal conditions does not have clinical relevance, except when salivary protective factors are reduced, as occurs during sleep and in the presence of xerostomia. 57 …”

Macronutrients and type 1 diabetes (revision number 6)

“…The acids that induce demineralisation at this level are produced by the fermentation of dietary sugars (including sugars produced by hydrolysis of starch in mouth), particularly sucrose, by acidogenic bacteria from the oral microbiota. Lactose is fermented more slowly than sucrose (Birkhed et al, 1993). Demineralisation from bacterially-derived acids (predominantly lactic acid) occurs during virtually every meal as natural sugars are present in virtually all foods.…”