Tripoding is a procedure which assist in repositioning the cast on a dental surveyor. It is indexing the cast in a horizontal plane after final tilt of cast is determined on the surveyor.
In Nallaswamy, It has asked that after tripoding in the primary cast we again take 3 reference points (Distal marginal ridge of first premolar, incisal edge of Lateral Incisor, and lingual cusp tip of opposite side premolar) while transferring the tripoding from primary to master cast. My question is, if we are already taking 3 points in the primary cast why do we require to take 3 other points just for transferring to master cast? Also as per this book, it's saying the choice of these points is based on *easy to locate* on the cast. Is there any reason behind the choice of these location? ? Sir please clarify
Purpose of tripoding is to preserve the final tilt of the cast in horizontal plane. Three reference points helps in positioning the cast (primary or master) any number of time in same position.
With tripoding you already scribe marks on cast at particular tilt. Inorder to reorient cast back you again ensure your analysing rod fits into those marks.
