tips and tricks

 Today I attended day 1 of the fixed prosthodontic course. In contrast to the removable prosthodontic course, I'm less keen on fixed pros though I don't mind it too much. He spent quite a while going over the basics of the topic including the theory behind bur design, some material science and advocated "prep design with intent". I sense he advocates against a cook book approach or a matrix within which to make decisions and rather advocates understanding the reasoning and thought process behind WHY we make the choices we do. Using this knowledge we can make treatment decisions individual to each patient and clinical situation. He does advocate crowns over veneers for upper anterior teeth and tends towards onlays for posterior teeth. The reasoning behind this takes into consideration the forces that each restoration is put under and the reason why the restoration is done i.e upper anterior veneers are upt under tensile stress so tend to fracture and debond more than i...

Following up on the difficult impression appointment from a previous post: https://dental-tidbits.blogspot.com/2021/04/difficult-impression-appointment.html The aim of preparation is to convert a difficult task to an easier one. The impression that I sent off that day turned out the be absolute rubbish and completely inappropriate for the final impression.  I could approach the case with a clear head and cleaned the old impression off the tray and placed adhesive long before the appointment. This way there was enough time for the solvent to evaporate and the adhesive to be effective.  I used light body PVS in every single cavity to block it out. I thought this would be difficult to handle but it was quite simple and if excess bled out of the cavity I could push it back in with an instrument. I had to change tips half way through because I was too slow in the placement and the material had early set half way through the blocking out. One thing I would change is to dry the teeth...

 Today I had a difficult impression appointment. The case is for a full upper immediate denture and the patient has almost all of his upper teeth that are badly broken down and carious. The issue with the impressions is that the material kept flowing into the carious areas, locking in and when I tried to remove the tray, the alginate would peel off the tray and tear. I retook the impression 4 times and in the end accepted a compromised result. I don't know how it will come back to bite me down the line but I know it will in some form or another. An important failure of mine here is that I didn't analyse how the first few impressions failed and try to learn from them for the next impression. Some thoughts: -The combination of locking in on the anterior and posterior teeth was enough to overcome the adhesion to the tray. When considering impression debonding it is merely a tug of war between the impression sticking to the tray and the impression sticking to the teeth. I think the...

 I had an endodontic mishap the other day which I am waiting to follow up to see the result of. The case was an extirpation of an upper lateral incisor. Due to the severe caries ring barking the tooth I cleared the decay and restored the tooth before placing a rubber dam. This is to ensure that the rubber dam seals against convex restoration rather than concave caries as well as for restorative ease to clear caries without the risk of catching the rubber dam on the bur and before rubber dam placement causes gingival bleeding. One thing I have done in the past is to avoid opening the pulp chamber before placing the rubber dam to avoid contamination of the pulp but realistically this isn't so much of a big deal if a dry field is kept and likely the root canal space is already infected. Instead, leaving caries to remove after restoration may result in more difficult access and a more difficult procedure. I place cavit over the caries to mark where I have to drill and to make reaccessi...

 Today I spent another day at the prosthodontic practice. It was a pretty packed day with a mixed bag of treatment, some cases just starting, some far along both surgery and fixed prosthodontics. -Bonded gold restorations lower canine buldup: The patient had a history of bruxism and had worn teeth. The anteriors had been restored as veneers in composite resin and the patient requested a gold restoration for the upper right premolar. The preparation was essentially a veneer with a buccal path of insertion. The veneer wrapped around over the buccal cusp with the finish line at the position of the cusp tip. It extended equigingival and mesially and distally between the line angles and the contact point, just far enough to mask tooth structure. In the middle of the facial surface there was a round 0.8mm diameter dent prepared into it for resistance form. The temporary restoration was a shrink wrap bisacryl which was locked into the interproximal undercut. There was an enamel chip on th...

 Today I made a few errors when recording and mounting a facebow record. Each facebow system works on the principle of providing 3 reference points to mount the maxillary cast. The anterior reference point is the occlusal plane of the maxilla and the 2 posterior points are the temperomandibular joints. There is a This approximates the position of the maxilla in relation to the terminal hinge axis but this can be any point in the arc. Due to this, another point is chosen in each facebow system to control where in the arc the model will be mounted. In this case there is a reference point at the infraorbital notch. This position will roughly place the models in the centre of the articulator in a vertical position.  In this case I forgot to use this fourth reference point and had the arm of the earpieces a tad too high. I was sure to make the ear piece bar parallel to the interpupillary line as this will give a realistic appraisal of any anterior occlusal cants on the mounted mode...