Development and psychometric evaluation of the Index of Dental Anxiety and Fear (IDAF-4C+).

The measurement of dental fear is important due to its high prevalence and appreciable individual, clinical, and public health consequences. However, existing measures of dental anxiety and fear (DAF) have theoretical or practical limitations. This study describes the development and subsequent assessment of the reliability and validity of test scores of a new DAF scale for adults. The Index of Dental Anxiety and Fear (IDAF-4C+) contains 3 modules that measure DAF, dental phobia, and feared dental stimuli. The final 8-item DAF module (IDAF-4C) assesses emotional, behavioral, physiological, and cognitive components of the anxiety and fear response. The proposed scale dimensionality received support from exploratory factor analysis. IDAF-4C items showed good internal consistency (Cronbach's alpha = .94) and test-retest reliability at 4 months (r = .82), and the scale was strongly associated with other dental fear scales as well as with dental visiting patterns, avoidance of the dentist, and dental phobia diagnosis. The convergent and predictive validity of the IDAF-4C compared positively to Corah's (1969; Corah, Gale, & Illig, 1978) Dental Anxiety Scale and a single-item measure of dental fear, and the scale predicted future dental visiting and visit perceptions. Both phobia and stimulus modules showed strong and statistically significant associations with DAF ratings. In all, sufficient evidence is provided to demonstrate that the new scale would be a useful tool to assess DAF in an adult population. The IDAF-4C+ is based on strong theoretical underpinnings, yet the scale is practical enough for application across a variety of potential uses.