The aim of this paper was to review in vitro and in situ studies that directly compared the use of bovine teeth as a substitute for human teeth in dental experiments. A PubMed search was conducted for papers published from 1953 to December 30, 2010 using the following keywords: “human bovine enamel” or “human bovine dentin” or “human bovine teeth”. The abstracts of the studies resulting from the keyword search were read, and all papers that compared human and bovine teeth were fully read. Only original articles written in English and directly comparing human and bovine substrates were included in the review. The search was supplemented by manual searches of the reference lists from each identified paper. Out of 76 studies initially selected, 68 fulfilled the selection criteria for inclusion. The studies covered seven categories: dental morphology, chemical composition, physical properties, dental caries, dental erosion/abrasion, bonding/adhesive strength, and marginal microleakage. Inconsistent data exist regarding whether bovine teeth can be considered an appropriate substitute for human teeth in dental research. Morphological, chemical compostion and physical property differences between the two substrates must be considered when interpreting results obtained from any experiment using bovine tooth substrate. (J Oral Sci 53, 273-282, 2011)

Significance: Dental caries remains an unresolved public health problem. The etiology is poorly understood, as the oral cavity harbors diverse communities of microorganisms. Using multiple imaging modalities on human teeth from patients with caries, we discovered a microbial community precisely arranged in a corona-like architecture. Moreover, this organization is mediated by the pathogen Streptococcus mutans through production of an extracellular scaffold that directs positioning of other oral microbes. We developed a methodology to quantify the spatial structure of microbial communities at the micron scale and found a precise spatial patterning of bacteria associated with localized caries onset. These findings are relevant as we approach the post-microbiome era, whereby quantifying the community structural organization may be essential for understanding microbiome function.

The advantages, limitations and potential applications of available methods for studying erosion of enamel and dentine are reviewed. Special emphasis is placed on the influence of histological differences between the dental hard tissue and the stage of the erosive lesion. No method is suitable for all stages of the lesion. Factors determining the applicability of the methods are: surface condition of the specimen, type of the experimental model, nature of the lesion, need for longitudinal measurements and type of outcome. The most suitable and most widely used methods are: chemical analyses of mineral release and enamel surface hardness for early erosion, and surface profilometry and microradiography for advanced erosion. Morphological changes in eroded dental tissue have usually been characterised by scanning electron microscopy. Novel methods have also been used, but little is known of their potential and limitations. Therefore, there is a need for their further development, evaluation, consolidation and, in particular, validation.

Saliva is the most relevant biological factor for the prevention of dental erosion. It starts acting even before the acid attack, with an increase of the salivary flow rate as a response to the acidic stimuli. This creates a more favorable scenario, improving the buffering system of saliva and effectively diluting and clearing acids that come in contact with dental surfaces during the erosive challenge. Saliva plays a role in the formation of the acquired dental pellicle, a perm-selective membrane that prevents the contact of the acid with the tooth surfaces. Due to its mineral content, saliva can prevent demineralization as well as enhance remineralization. These protective properties may become more evident in hyposalivatory patients. Finally, saliva may also represent the biological expression of an individual's risk for developing erosive lesions; therefore, some of the saliva components as well as of the acquired dental pellicle can serve as potential biomarkers for dental erosion.

The acquired dental pellicle helps prevent erosion, but the protection level is unknown. This in situ study tested whether a two-hour pellicle protects against different erosive challenges by orange juice. Subjects wore palatal appliances loaded with either enamel or dentin specimens. Pellicle was allowed to form, or not (control), on the surfaces of the specimens intra-orally for 2 hrs before the erosive challenges of 0 (control), 10, 20, and 30 minutes’ duration. Specimens were randomly removed from the appliances after each challenge. Percentage of surface microhardness change (%SMC) was determined for the enamel specimens, and that of mineral loss and lesion depth for the dentin specimens. Enamel specimens with the pellicle showed a significantly lower %SMC, only after the 10-minute challenge. No protection was found for dentin. It was concluded that the acquired pellicle reduced dental erosion, but that this effect was limited to the less severe erosive challenge on enamel surfaces.