Resetting denture teeth

 Today I had the worst denture try in that I've ever had. The situation was the construction of a full over partial denture. The patient has a current full denture which he doesn't like the aesthetics of feeling the teeth aren't visible enough. He is a person who is a bit past a mid life crisis and spends his days chasing after women half his age. But to be fair, the incisal display was inadequate and unless he had a very wide smile, he looked edentulous and unsupported lip-wise. Naturally I took my jaw registration intending to increase the incisal display and ordered the A1 teeth to be set. 

I don't know how it was so wrong but the midline was off by about 5mm and the incisal edge was down by about 5mm. I have never seen a sight more horrible. To my annoyance, the wax rims I had sent up were still sitting in the lab box meaning the technician had supposedly used them to mount the case and then set the teeth up without it. They can make an index over the lower cast to record the desired position of the incisal edges and set the upper teeth without the rim however I think they just eyeballed it and just matched the upper incisal edge with the lower natural teeth. I suspect this as well because there were no markings on the cast at all to note the midline. This is how I explained the midline shift but to their credit, the bite was reproducibly spot on which means at the very least they used the bite registration I had given to mount the case and hadn't changed the pin position on the articulator otherwise the bite would be off. This means that it was my fault that the teeth were set so horribly long.

When the aesthetics of the case is off, I remedy the situation by resetting the 6 anterior teeth, knocking off the posterior teeth, remaking the rim on the posterior and retaking the bite. Usually with minor corrections I can eyeball it e.g move the incisors 1mm upwards or labially but with such a large discrepancy I found it useful to use a pencil to mark the new desired incisal edge and midline. This is the starting point of any aesthetic rehabilitation. I marked these lines and put the denture back in to see if it worked with his lip position and smile. Once this was confirmed, I marked the midline position on the cast land area with a pencil and on the gingival wax with a lecron. I knocked off the tooth that was crossing the midline and set in in the right position according to the pencil line across the teeth marking the incisal edge and the vertical line denoting the midline. I tried this back in as a proof of concept and on seeing it was in a good position I knocked off the lateral, canine and premolar on the same side and set them according to the curvature of the arch. I then tried this back in the check the incisal plane was correct then did the same to the other side. Once the patient and I were happy with the aesthetics, I knocked off the posterior teeth and retook the bite. To remake the rim, I used a heated wax knife to flatten the "papillae", then heated and rolled a sheet of wax, cut 2 rolls placing them on the posteirior areas then sealed them to the rim with a heated wax knife. I then retook the bite at the closed vertical dimension. 

Due to the limited time frame of the case, I took to the lab and set the rest of the posterior teeth. I noted that the lab had also not set the lower posterior teeth over the ridge (a common error). These were set buccal to the ridge which meant that if the upper molars were set to the normal overbite and overjet they would be even further buccal to the ridge which would tend to tip the dentures. What I most commonly see as a solution and what annoys me to no end is that they get around this by setting the upper teeth in palatal crossbite. In this case the small error of them overtrimming the cast and completely removing the lower land area meant that they couldn't mark the line to indicate the position of the ridge which meant that they set the teeth buccal to the ridge and the upper teeth were set in cross bite. This series of compounding errors serves to highlight how important each step in the prosthodontic series is and how little errors, short cuts or mistakes will result in a substandard outcome in the final product. I ended up setting the lower posterior teeth lingually and so could set the upper posterior teeth in a good relationship. I aimed for a lingualised occlusion but discovered that the appropriately designed teeth need to be used because if the upper teeth were set tilted to the buccal to allow the palatal cusp tip to hang down, the buccal surface will appear too flared out with anatomic teeth. Also, with anatomic lower teeth, you have to be very particular as to where the contact of the upper cusp sits because there are so many inclined planes not only in the buccolingual aspect but the mesiodistal aspect as well. Using non anatomic or semianatomic teeth allows setting of upper palatal cusps against lower teeth in any position in a mesiodistal direction as long as it is placed along the central fissure. I also discovered that it is more difficult to handle wax and set teeth than I thought. It is difficult to see the finer details of occlusion and setting teeth especially when you are almost finished and there are all the tooth contacts to consider at once. The best way to manage this is to make sure the occlusion is correct after each tooth is set i.e is the contact over the lower central fissure, is the tooth in the correct aesthetic orientation and is the pin still touching. If so then move onto the next tooth. Once all the teeth were set, I scooped wax onto the palatal aspect to tack the teeth still, used a heated lecron to melt the buccal wax, remove bubbles and provide more support for the teeth on the buccal aspect. When this had cooled I went and melted the wax on the palatal to remove bubbles. I carved the gignival margins and used a blowtowrch to smooth the wax. 

I will wait for the patient's next appointment to see how my set up turns out. I might find that it is more difficult to achieve a good result that I think.