Abstract Introduction The purpose of this study was to evaluate if agenesis of one or more third molars would delay the development of the remaining third molars (1-3), and if the agenesis influence the dental age estimation. Lastly, we wished to explore if the present methods are accurate. Methods Dental panoramic radiographs from 2008-2015 of 210 patients, who turned 18 years the calendar year the OPGs were taken at The Faculty of Dentistry in Oslo, were divided into two groups consisting of one control group (105 individuals), where none had agenesis, and one test group (105 individuals), where the individuals showed agenesis of one or more wisdom teeth. Scoring systems of tooth development by Moorrees, Fanning et al. (1963), and Demirijan et al. (1973) were used on the third molar present, and converted to age assessment by tables published by Haavikko (1970), Liversidge (2008), and Mincer et al. (1993). Results The majority of the test group had agenesis of two teeth (55%), 40% had agenesis of one tooth and only 5% had agenesis of three teeth. The test group was not subdivided. When comparing the two groups according to both Demiirjan et al. and Morrees and Fanning et al., the distribution in dental development is delayed in the test group. Examination of wisdom teeth in this group resulted in several teeth in early root development stages, whilst in the control group they were in late root developmental stages. The majority of examined tooth in this group were teeth with fully closed apex or in the final root development stage. Conclusion Agenesis of third molars results in delayed mineralization of the remaining third molars, and there were no difference using tables by Liversidge or Mincer to estimate age.