This is a little tip for ensuring smile designs go right first time, and it involves an accurate impression of the palate at pre-op impression stage... let me explain.
When we do diagnostic wax ups for crowns or veneers we make 2 matrices to help with the preps, one shows buccal reduction and one show incisal reduction. The key point here is that the incisal reduction matrix often only locates on the palate, especially when posteriors are also being included in the smile design.
After you have prepared the veneers/crowns and we come to make the definitive restorations we use this matrix to build the restorations in to, this ensures we position the incisal edges in exactly the right place. Once again this matrix often locates on the palate only, so if the impressions of the palates from the original diagnostic and the definitive preps don't match then we are not always able to transfer this matrix.... possibilities for errors creep in!
So, although the impression of the teeth and preps is vital, for complete reliability and to reduce the chance of uncertainty, we need an accurate impression of the palate on both the original diagnostic and the final prep impressions.
When we do diagnostic wax ups for crowns or veneers we make 2 matrices to help with the preps, one shows buccal reduction and one show incisal reduction. The key point here is that the incisal reduction matrix often only locates on the palate, especially when posteriors are also being included in the smile design.
After you have prepared the veneers/crowns and we come to make the definitive restorations we use this matrix to build the restorations in to, this ensures we position the incisal edges in exactly the right place. Once again this matrix often locates on the palate only, so if the impressions of the palates from the original diagnostic and the definitive preps don't match then we are not always able to transfer this matrix.... possibilities for errors creep in!
So, although the impression of the teeth and preps is vital, for complete reliability and to reduce the chance of uncertainty, we need an accurate impression of the palate on both the original diagnostic and the final prep impressions.
Nice post Mark, I really like the picture blogs! It's great to hear about things from the other side of the dental experience.
ReplyDeleteI had a question. Saw an article about using polethene matrix strips between anterior crown preps so they pick up in the imp. Apparently it makes sectioning the dies easier and safer for the technician. Would be interested to know your point of view.
Keep up the great blog
Chris
Strips work well Chris and they do allow us to separate dies easier.
ReplyDeleteGo ahead and use them please!
Mark