Consideraciones de la reproducibilidad de posición natural de la cabeza utilizando diferentes métodos

The aim of this study was to investigate the reproducibility of Natural Head Position (NHP) in photographic and radiographic records. In a random sample of 51 subjects NHP was radiographic and photographic recorded. It was drawn “variable 1a”; angle between true vertical an E Line to evaluate NHP reproducibility and method agreement. Results showed good reproducibility of NHP (SD 2,60 or less) for all photographic methods. It was observed a good method agreement between the mirror and the operator corrected method, showing this last method better results of reproducibility (SD 2,23). Method agreement between photographic and radiographic records in NHP was good (SD 1,67). Despite the good reproducibility results using Dahlberg coefficient (1,83 or less), up to the 17% of the sample showed difference in head position greater than 5° in some moments. Dahlberg coefficient (1,83) used commonly to assess reproducibility only provides a 52% interval which is not wide enough for clinical assessment of the method evaluated, however reproducibility coefficient (4,55 or less) provides a 95% interval which coincides with two typical deviation of a normal distribution and represents better the clinical evaluation of the investigated method.