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The purpose of the study was to determine whether adding calcium lactate to chewing gum containing xylitol enhances remineralization of enamel surfaces using an early caries lesion model. Enamel slabs were cut from human extracted sound teeth and artificial subsurface lesions created within each. Half the enamel slabs were used as controls and stored in a humidifier while half were mounted into oral appliances worn by 10 volunteers (22–27 years old, 2 males and 8 females) in a three-leg trial, during which they wore the appliance without chewing gum, chewed gum containing xylitol + calcium lactate or chewed gum containing only xylitol 4 times a day for 2 weeks. Calcium concentrations in the enamel surfaces of control and test slabs were measured by X-ray spectrometry and degrees of remineralization were calculated. The mean degree of remineralization was greater after chewing xylitol-Ca gum (0.46 ± 0.10) than after no gum (0.16 ± 0.14) or after chewing xylitol gum (0.33 ± 0.10) (p < 0.01). In conclusion, chewing gum containing xylitol + calcium lactate could enhance remineralization of enamel surface compared to chewing gum containing only xylitol or no gum chewing.

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In myotome muscle fibers composing the trunk of the lamprey (Lamperrajapomba), parietal muscle fibers and central muscle fibers, which are histochemically and functionally different from each other, formed single compartments which then formed multiple units. Parietal muscle fibers arranged like a chain in the lateralis, were histochemically identified as red muscle fibers, and classified as slow contracting fibers (Type 1). In contrast, central muscle fibers were present in the medialis surrounded by parietal muscle fibers and histochemically were fast contracting white muscle fibers (Type 2). These observations of the architecture of muscle fibers and muscle fiber types suggest that red muscle fibers (parietal muscle fibers) forming the lateralis of the lamprey are involved in trunk architecture because of their continuous tonic contraction, and white muscle fibers (central muscle fibers) located in the medialis function act as a propelling force used in swimming.