Purpose The main purpose was to study young patients’ self-reports on dental fear over a 5-year period, prospectively. Also, to compare these to professionals’ proxy reports for dental fear during invasive and non-invasive dental visits. The research question was, to what extent the self-reports and dental professionals’ proxy reports are congruent, and if there were patient age-dependent differences. Methods 3134 patients from 11 public dental clinics, representing urban and rural areas, were invited. Four age cohorts were formed: 3, 7, 11, and 15 years of age and followed between the years 2008 and 2012. Dental examinations (non-invasive) and restorative treatments + extractions (invasive) were registered. During the treatments, self-reports regarding fear and professional proxy reports were registered: Not afraid at all = 0, little nervous = 1, quite afraid = 2, very scared = 3, terrified = 4. Results 2363 patients completed the cohort periods (51% girls and 49% boys). In all, 9708 dental examinations, restorations and extractions were performed. The fear prevalence increased with the invasiveness of the dental procedure; 7–56%. For dental examinations and restorations, fear declined with ascending age. The highest fear prevalence was reported for dental extractions. Younger children reported fear more frequently than older children, p < 0.001. Frequent inconsistencies between self-reports and proxy reports were observed among the younger children (16%) compared to the older children (8%), p < 0.001. Conclusion Non-congruence was observed for self-reports and proxy reports regarding all age cohorts.