ABSTRACT
CONTEXT: By convention, the posterior palatal seal area is located on the palate between the anterior and posterior vibrating lines. However, there are opposing views on whether the anterior and posterior vibrating lines can be distinguished as two separate lines of flexion. AIMS: The study was carried out to determine whether the anterior and posterior vibrating lines can be distinguished as two separate lines of flexion by unbiased observers. A second part of the study was formulated to evaluate whether the palpatory method correlated with the nose-blowing method in locating the anterior line of flexion. MATERIALS AND METHODS: Twenty-three dental undergraduate clinical students were selected as observers. Twenty-three edentulous patients were randomly selected. The students were asked to record the anterior and posterior vibrating line on one patient each using two differently colored marking pencils. Also, the anterior vibrating line was marked by the palpatory method (using T burnisher) using a third colored marking pencil. The marked lines were then transferred onto the previously made impression of modeling plastic. RESULTS: Of the 23 recorders used in the study, 19 could locate separate anterior and posterior lines of flexion. In 4 cases, the anterior and posterior lines of flexion coincided and were not distinct. In 20 cases, the palpatory method produced a line anterior to the line located by the Valsalva maneuver. CONCLUSIONS: The anterior and posterior vibrating lines could be located by the undergraduate students as two separate lines of flexion when the appropriate action was elicited for each of them; and the palpatory method produced a line slightly anterior to the anterior vibrating line located by the Valsalva maneuver.