Optimum bitewing examination recall intervals assessed by computer simulation

To assess the effect of altering bitewing examination recall intervals on health gain from dental restorative treatment and to determine optimum recall intervals under varying clinical conditions.

A computer simulation of the caries process in posterior approximal tooth surfaces. The effect of superimposing restorative treatment, based on diagnoses from bitewing radiological examinations carried out at differing time intervals, was incorporated. Input data included caries attack rates, median survival times of restorations, and sensitivity (Sn) and specificity (Sp) of treatment decision making by a high (A) and a low (B) performing dentist.

A hypothetical population, initially 14-15 years old.

Class II amalgam restorations.

Health gain in utility based units (UBUs) was assessed relative to interim end point UBUs pertaining under 'do nothing scenarios'.

One thousand approximal surfaces, designated initially as 920 sound, 51 carious and 29 filled were followed in the model over 10 years. The greatest health gain (39.33 UBUs) was from dentist A (Sn = 0.23, Sp = 0.99, restoration median survival time = 20 years, caries rate = 4.4% per annum, optimal recall interval between bitewing radiological examinations = 7 months). The least was from dentist B (Sn = 0.52, Sp = 0.88, median survival time = 5 years. caries rate = 0.0% per annum, optimal recall interval between bitewing radiological examinations > 120 months) representing a loss of 16.79 UBUs compared with 'do nothing'.

In the best interests of their patients, it would seem that dentists need to exercise considerable caution in making positive decisions to restore approximal tooth surfaces on the basis of bitewing radiographic evidence and that for some dentists current guidelines for bitewing examination intervals would appear to be too permissive.