In the education of endodontics at the Subfaculty of Dentistry in Groningen mechanical cleaning of the root canal was supported by the use of medicaments containing formaldehyde, to fixate and eliminate inaccessable organic material. This thesis comprises a comparative study of the effects of formaldehyde and of glutardialdehyde on dentine and periapical tissue. Glutardialdehyde proved to be non-irritant and advantageous in fixation, mechanical cleaning and closing off the root canal. The thesis was followed-up on by research on the inhibiting properties of glutardialdehyde on dentine.