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| Overcoming Complete Denture Pitfalls |
From clinical considerations, to patient's expectations, the complete denture rehabilitation is full of pitfalls. The clinical aspects of complete dentures are notoriously known in modern dentistry as one of the most time consuming and least productive uses of time management. The concept of replacing all of the teeth, lost bone and tissue support from one or both arches has many areas where conflicts can arise.
Over the last thirty years, we have developed and perfected our own technique that has greatly enhanced the success of our clients' complete denture cases. We call it our "Modified Denture Technique". With this technique, we utilize the patient's existing complete dentures as a guide to the fabrication of their new dentures. Most complete denture wearers already have an existing set of dentures that they are wearing and are used to. They have come to acknowledge the tooth shade, shape and positions as being comforting. Any dramatic changes are usually seen as objectionable. It's almost like the feeling of replacing an old pair of shoes. You know it's time for a change as the old ones are worn out and unappealing. It's just that the new ones don't seem quite right. It's not that the new ones aren't better, it's they are just different. The concept of the denture technique stems from creating new dentures that improve fit, function and aesthetics, while at the same time maintaining as many similarit ies to the old set of dentures as possible. The procedure, as an added bonus requires less appointments and provides for a reduced laboratory fee, as the need for custom trays and bite blocks are eliminated.
We start by accessing why the patient requires a new denture i.e. loss of function, fit or aesthetics and determine what it is we are trying to achieve with the new dentures. With this in mind, we are ready to proceed.
The denture bases are assessed and prepared for a typical reline impression. Any gross undercuts on the tissue surface of the acrylic base are removed. If areas of the flanges need to be lengthened to extend the reach of the acrylic into tissue undercuts, border-molding compound needs to be applied. In most cases the flange length has been comfortable to the patient and any lengthening can result in sore areas and discomfort, so try to minimize the lengthening of the flanges if at all possible.
The next step involves taking a wash reline inside the denture . Depending on the amount of space inside the denture, a light or medium bodied impression material should be used to fill the void between the acrylic and the tissues. The original denture acts as the custom tray for all intents and purposes. (Figure 1) Once the impressions are done, it's time to establish the bite and determine if the vertical dimension needs adjusting to allow for the proper amount of freeway space as well as restore any lost facial characteristics.
With the reline impressions now complete, it is time to check the accuracy of the vertical dimension of the existing dentures. With the patient sitting up straight with his oral muscles in a relaxed state, measure the distance between two points on the patient's face; for example, the base of the nose and a mark on the chin, (Figure 2) while the patient is producing a "mmmmm" sound . This will approximate the vertical dimension that the patient requires for adequate freeway space. Now, have the patient occlude with the dentures in place and measure the distance once again. From the differences in these two measurements we can determine if and by how much the new dentures will be required to open the bite. This information can easily be related to the laboratory on the prescription. A centric occlusion bite is now done with a semi-rigid bite material using the closed mouth bite technique . This technique has the patient occlude his teeth together and once the relationship has been confirmed, bite material is injected onto the labial and buccal areas of the teeth. Once the bite material has set, the two dentures and the bite registration material are removed from the mouth in one piece and sent to the laboratory with instructions. (Figure 3)
In the lab, both arch impressions are poured and mounted onto an articulator with an anterior pin. A silicone or wax matrix is made that records the upper anterior tooth position in relation to the lower arch, i.e. midline, overbite, and over jet. Prior to the tooth set-up, any changes that the restorative dentist has noted on the prescription are taken into consideration. This could be in relation to increasing the vertical dimension, changing the shade of the denture teeth, etc. The dentures are removed from the mounting on the articulator and tooth selection is done usually to match a similar mould, size and shade to the patient's existing dentures. The original dentures are cleaned and returned to the dental office, usually on the same day. To enhance the fit of the old dentures while the new dentures are being made, a temporary, chair-side soft liner can be placed. To speed up the process, the patient can bring his impressions to the lab and wait for them to be given back. This is done so the patients don't have to go without their teeth for a long period of time. The in-lab procedures usually only takes a few hours.
In the lab, the teeth are set up in wax and are returned several days later to the office for a try in. Once the set up has been approved, final processing, trimming and polishing is done, and the completed dentures are ready for insertion. (Figure 4)
In most cases, only one try in appointment is needed and patient acceptance is easier to obtain since the new dentures have many similarities to the original pair. Most of the modifications are also easier for the patient to accept, as they will seem only minor, however they will most likely greatly enhance the fit, function and overall aesthetics for the patient. This technique can also be used when replacing only one complete denture in either of the arches, opposing natural dentition or an arch, which has a partial denture, as long as a mould of the opposing arch is also taken and sent to the lab.
Replacing worn, complete dentures does not have to be a complex procedure, providing that we make use of the information provided to us from the patient's original dentures.
i Pound, Earl, DDS. Personalized Denture Procedures: Dentist manual: Anaheim, California, USA: Denar Corp. 1973: pg 67
ii Ivoclar OPA Ruler Guidelines, Ivoclar North America Inc., 1991
iii Heinenberg, Bernd-Jorg. Ivoclar Prosthetic Systems Manual, Ivoclar AG, Shaan/Liechenstein, 1990; pg70
Ron Klausz, R.D.T. is owner of Klausz Dental Laboratories, located in North York, Ontario. A second generation registered dental technologist, he has chosen to follow in his father's footsteps. He keeps with the family traditions of producing advanced, high quality restorations while developing unique client and patient care services. He has modernized a company, whose focus is still based on fulfilling client needs. "Working harder and smarter for your practice!" is their credo.
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