Clinical review of patients with fixed bridges (2). A study of deviations between observers.

Abstract

Summary (Part 1 and 2)The authors have made a study of observer deviations in the re‐examination of patients with fixed bridges. The material consisted of eighteen patients who have had their bridges for about 2 years. The total number of bridge‐elements was 126, including eighty‐three abutment teeth and forty‐three politics.Nine observers have taken part. Of these, three have been teachers and six post‐clinical students, so that it has been possible to say that the observers had more, and lesser, experience of routine observation.The recorded factors have been: (1) primary contact; (2) the general status of the marginal periodontium; (3) calculus; (4) caries; (5) periapical status; (6) attrition facet; (7) abrasion in the opposing jaw; (8) crown margin excess; (9) crown margin deficit; (10) exposed crown margin; (11) pocket formation; (12) discolouration of gold.The examinations have been carried out in a conventional milieu with the usual instruments for examination and with access to orthopantomograms. The recordings have been made after independent as well as cumulative and simultaneous examination. In the last two cases the observers have been divided into three groups.A very simple account of the results regarding the first five factors is given. It is quite clear, however, that the nine observers record different totals and that positive finds are at the same time seldom reported by all.Each of the seven remaining factors has given rise to a larger number of (positive) recordings, so that a more detailed processing has been meaningful. Within each factor (with a certain exception for abrasion) considerable deviations are found between the nine independent observers in the matter of totals. It has been possible with analysis of variance to confirm, to a great extent, these deviations as significantly systematic. In connection with the change to cumulative and simultaneous observer strategy it has been possible to note certain improvements. It has not, however, been possible to designate the agreement between the three observer groups as appreciable. On the other hand, the number of positive recordings increases most frequently in connection with the changes to (Cum) and still more with the change to (Sim).The nine observers change level in relation to one another on moving from the one factor to the other. Within a certain factor they sometimes vary also between different patients, though a certain logical pattern appears. Through comparisons in pairs and the calculation of the correlation (expressed through the coefficient r) it has been possible to show that the correlation between the recordings of two observers is not always satisfactory. However, the conventional limit + 0.70 is exceeded in the majority of cases.The two groups of observers do not differ characteristically from each other factor by factor, (the factors ‘general status of the periodontium’ and ‘crown margin excess’ constitute exceptions). Both teachers and students change position in an irregular way. Each one of the nine observers may occur alternately as a high and a low recorder.The authors recommend further studies in this field with the aim of throwing light upon the homogenization of observers and becoming better informed concerning the precise significance of utilizing different observer strategies.