The outflow of orthodontists through retirement is an important factor in the estimation of the required training capacity for this group of professionals. From 2002 through 2018, studies of the professional activity and retirement plans of orthodontists age 55 and older have been conducted fairly frequently, the most recent one dating from 2018. Based on the findings of these surveys, 3 estimations were obtained of the outflow through retirement. These were based on answers in earlier editions, the answers of their contemporaries and on the basis of the legal retirement age in the Netherlands. The number of active orthodontists in 2018 age 55 or older is estimated respectively to be 117, 116 and 102; according to all estimations, they will have retired in 2030. The estimations predict, respectively 56, 57 and 30 orthodontists will retire before 2023. According to 2 of the estimations, the outflow of orthodontists from the field will exceed the inflow from the universities in the coming years. The present training capacity in the Netherlands is not sufficient to compensate for the outflow of the first 2 estimations.