For decades, the molecular and cellular mechanisms that govern tooth development have been extensively investigated. However, most of the studies are based on mice, whose teeth are quite different from human teeth in morphological and developmental aspects. Mice are not the ideal model for understanding the development of permanent teeth as they have only one set of dentition. Thus, using of diphyodont mammals is a better model to study the deciduous and permanent tooth development and to understand the process of tooth replacement. Several diphyodont mammal models have been established including minipig, ferret, house shrew and rabbit. Studies based on the diphyodont mammals have characterized the morphological changes involved in tooth replacement and molecular mechanisms of tooth replacement. However, few developmental stages were studied on ferret due to the presence of seasonal estrus and the difficulty to obtain ferret embryos at the correct stage. The house shrew is limited as a model because their deciduous tooth germs become vestigial in the embryonic period. The main disadvantage of the rabbit is an incomplete dentition with the lack of canines. Compared to the above mentioned animal models, the miniature pig has proven to be a valuable animal model for diphyodont development due to its dentition similarities, including the morphology, number and size of teeth, to human′s, and particularly its heterodont dentition consisting of incisors, canines, premolars and molars. The present article reviews the current knowledge on the development of the primary and successional teeth in minipig modle and briefly summarizes the studies based on other diphyodont mammal models.

In recent years, the bloodstream infection rate of Gram-negative bacilli has continued to increase. Among them, drug-resistant bacteria have a higher mortality rate and longer hospital stay, especially the bloodstream infection of carbapenem-resistant Acinetobacter baumannii (CRAB). Polymyxin began to be used clinically in the 1950s and has antibacterial activity against multidrug resistant and poly drug-resistant Gram-negative bacilli. It can also be used as an effective permeation agent for the cell envelope of Gram-negative bacilli. Polymyxin is reserved for microbiologically clear drug-resistant Gram-negative bacilli infections. The World Health Organization classifies polymyxin as an antimicrobial drug with clinical significance for human infections and can be used to treat drug-resistant Acinetobacter baumannii infection. This article reviews the clinical treatment of polymyxin in bloodstream infections of drug-resistant Acinetobacter baumannii, to provide reference for clinical medication.