Every year in the United States, millions of animals including monkey's, rats, mice, rabbits, cats, and dogs suffer experimentation to test the biocompatibility of products before they are used on humans. Some of the most inhumane experimentation is performed on pregnant animals for embryo-toxicity testing. Biocompatibility and embryo-toxicity screening assays evaluate the potential health hazards to humans, and must be performed by companies to ensure that a new biomaterial will not kill or harm patients. All new biomaterials must be evaluated according to biocompatibility screening guidelines 7405 and 10993, formulated and updated in 1997 by the International Organization for Standardization (IOS). The IOS recommended the development of new investigative approaches to serve as an alternative to live animal testing, but none, or few alternatives have been developed so far. The purpose of this project is to develop biocompatibility and embryo-toxicity screening methods that avoid animal experimentation by using tissue and cell cultures as replacements to animals. This will be accomplished in the following specific aims: Specific Aim 1. We will develop the tooth slice tissue culture technique as a biocompatibility test method. Specific Aim 2. We will develop a stem cell culture technique as a embryo-toxicity test method. These techniques have the potential to i) replace many animal experiments for product testing, ii) reduce the number and type of animal experiments necessary to evaluate products, iii) propose changes to the IOS biocompatibility and embryo-toxicity screening guidelines so that all companies, institutions and investigators are responsible for implementing the use of alternative screening methodologies as an alternative to animal experimentation.