Other tools that can be used for diagnostic purposes include the physiological and hormonal measures. Several investigations have measured children?s physiological reactions to dental settings^20,28,32. These indirect measures of dental fear assesses heart rate, pulse rate, skin conductance, muscles tension, blood pressure, palmer sweating and decreased salivary secretion^33,34. Meyers et al³⁵ reported an increase in heart rate prior to and during injections. There are phases in dental treatments when increased anxiety would be expected and this does not necessarily translate to the fear of the situation.

A limitation to the use of these tests includes the fact that such techniques are restricted to specific test situations and requires special equipments. This in itself could affect results because the equipment could provoke anxiety³⁰. Bastawi et al³⁶ observed that a non-fearful child might be disturbed only by procedures perceived as overtly threatening. These changes in body physiological parameters at such times do not make the patient a dentally anxious patient. Also, the dentist must have some experience in using and interpreting results from the specialized equipments not used in the normal remit of practice³⁷. It is also a time consuming method.

The measurement of free cortisol in saliva has been found to be a reliable method of measuring stress and fear in children. Stress activates the production of adrenal hormones^38-40 and the amount of salivary cortisol is equal to free cortisol in serum^39,40. Thus the measurement of free salivary cortisol offers a convenient way to monitor the systemic adrenocortisol response to stimuli.

Studies have found a significant correlation was found between fear and salivary cortisol^41-43. Although this technique is non-invasive, it requires special equipments and studies can only be done on few selected patient samples. However, the influences of variables like age and sex on the results have not been evaluated.

Projection techniques are of special interest as they suggest a way of revealing unconscious or hidden emotions. They enable information to be obtained about a child?s feelings and thoughts about dental care³⁰ which may be hard to obtain through other methods. The technique includes, for example, the child?s interpretation of picture stories, the child?s drawing of a person, the child being asked to tell a story about something or someone. These measures are used commonly in clinical child psychology⁴⁴.

The frequent form of use of this technique has been letting a child draw a picture of a person^31,44-46 and the interpretation of pictures in stories. In 1986, Nelson and Cholera⁴⁷ published the report of a study done on this form of diagnosis of dental fear in children. The assessment showed comparable results with the observed behaviour of children in the dental chair as well as with self reports of dental anxiety. Unfortunately, no data was presented on the reliability and validity of this method of assessing dental fear¹⁷.

Klingberg and Hwang¹⁷ also developed The Child Dental Fear Picture Test as a projective technique for measuring dental fear. A study done by Klingberg et al⁴⁸ ascertained the validity of this instrument and it showed high values of sensitivity and specificity for the measurement of dental fear.

The projection technique however, suffers from questionable reliability and validity due to difficulties in the interpretation of stories and the standardization of scoring³⁷. At best, a statistically significant weak correlation between drawing a picture and age, physiological response and behaviour ratings was establish by Sonnenberg and Venham²¹. Its use is also limited because an expert is required to carry out the interview and score the tests.

Psychometric questionnaires directly measuring dental fear and designed to be filled out by parents helped to overcome some of the problems identified with the tools discussed above. A short schedule would be more appropriate for use in the clinic. However, the choice of schedule to use would depend on the objective of the assessment. The DFSS-SF may be helpful while the CFSS-DS would help give a more detailed perspective of the causes of dental fear in the child.