Transient acid-impairment of growth ability of oral Streptococcus, Actinomyces, and Lactobacillus: a possible ecological determinant in dental plaque.

Introduction: Dental plaque pH decreases to about 4 through bacterial fermentation of carbohydrates and this low pH is maintained for from several minutes to about an hour. Repeated acidification causes demineralization of the tooth surface, resulting in caries formation. The acidification also influences plaque bacteria.

Effects of alpha-amylase and its inhibitors on acid production from cooked starch by oral streptococci.

This study evaluated acid production from cooked starch by Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus mitis, and the effects of alpha-amylase inhibitors (maltotriitol and acarbose) and xylitol on acid production. Streptococcal cell suspensions were anaerobically incubated with various carbohydrates that included cooked potato starch in the presence or absence of alpha-amylase. Subsequently, the fall in pH and the acid production rate at pH 7.

Multiple lesions of intracoronal resorption of permanent teeth in the developing dentition: a case report.

The purpose of this case report is to describe an unusual presentation of multiple lesions of intracoronal resorption in the permanent teeth in a healthy boy. Longitudinal radiographs demonstrated that all 3 lesions were acquired after the crowns were completely formed. Unlike previous reports in which intracoronal radiolucencies have been found in unerupted teeth or in newly erupting teeth, one lesion in this case developed in a fully erupted tooth, which was differentiated from internal resorption and invasive cervical resorption of the root.

The MMP activity in developing rat molar roots and incisors demonstrated by in situ zymography.

Matrix metalloproteinases (MMPs) have been expressed during root development and periodontal tissue formation, whereas it is not known if these MMP molecules are enzymatically active to degrade the extracellular matrices (ECMs). The present study was designed to investigate the gelatinolytic and collagenolytic activity in rat molar root and incisor development. Three-week old rat mandibles were frozen and cut without fixation or decalcification and processed for in situ zymography using substrates gelatin and collagen.

Distinct spatiotemporal expression of EFA6D, a guanine nucleotide exchange factor for ARF6, among the EFA6 family in mouse brain.

The EFA6 family is a member of guanine nucleotide exchange factors (GEFs) that can activate ARF6 specifically in vitro. In this study, we determined the complete primary sequence of mouse EFA6D encoding a protein of 1004 amino acids with a calculated molecular weight of 111,207 Da. In ARF pull-down assay, EFA6D showed a preferential GEF activity toward ARF6.