In order to substantiate biocompatibility of dental materials and techniques and thereby reduce iatrogenesis, tests for pulpal and dentinal responses have been developed. These have shown that: high-speed tooth cutting techniques are superior to low-speed techniques even when both incorporate air and water coolant sprays; pressure when condensing restorative materials intensifies pulpal responses induced by the cutting procedure, and that chemically self-cured resin composites requiring the application of a matrix to enhance adaptation intensify pulpal response as compared to visible light-cured equivalents applied incrementally, fully cured throughout and not requiring the pressure of a matrix. Most cements are irritating to the pulp especially when used as luting agents and when used less than 0.5 mm from it. Conditioning agents utilising weak acids for short periods induce little irritation whilst bonding agents appear to be beneficial by providing protection from subsequently placed restorative materials. Clinicians should make every effort to minimise the development of pulpal responses and reduce iatrogenic effects.