Sir, good measurement is the keystone to the scientific method. It is heartening to see therefore the paper by Shokouhi and Kerr in this Journal reviewing the Indicator of Sedation Need (IOSN).1 We note under the section of 'patient anxiety' that the Corah's dental anxiety scale (CDAS) might be considered as more accurate than the current measure: modified dental anxiety scale (MDAS). The basis of Shokouhi and Kerr's argument is a review of 15 dental anxiety measures by Newton and Buck published 18 years ago.2 We would caution substituting MDAS with CDAS based upon a review that is almost two decades old. The MDAS has now replaced the CDAS in study reports dated this century (88 vs 13 PubMed hits MDAS vs CDAS dental anxiety) and has extensive age/gender UK normative values.3 The recommendation should therefore hold to retain the MDAS as the recognised assessment of dental anxiety in the IOSN. We value the attention to the often neglected subject area of psychometrics in clinical assessment and decision making. It is hoped that this note will have made a useful addition to the continuing development of the IOSN.