The incidental detection of asymptomatic apical periodontitis raises the question of whether or not this lesion should be treated. Arguments favoring treatment are that the inflammation may cause pain in the future, may enlarge, or may negatively affect the host's resistance. Reasons for not treating may be that treatment weakens the tooth, may cause iatrogenic damage, and that treatment is expensive and burdensome for the patient and does not lead to complete recovery in all cases. Scientific evidence supporting either choice, whether treating the lesion or not, is lacking. Therefore, in making such decisions, the personal judgements of the patient and the dentist concerning the impact on the quality of life of the patient play an important role.