Treating the totally edentulous patient has been neglected by many dentists because of the difficulties in techniques and approaches. Competent care of the edentulous patient is needed, and this need will continue for decades.
Although, most denture failures are associated with underextended denture bases and occlusal disharmony, some patients still have problems with well-done conventional approached complete dentures. Clinical dilemma occurs when patient with severely resorbed mandibular edentulous ridge come with a bag full of dentures and the chief complaint is “it just doesn’t fit.”. An alternative way to approach the case besides the conventional techniques should be considered.
The techniques presented incorporate the neutral zone concept to the conventional techniques by modifying the techniques of occlusion rims fabrication and denture teeth set up. The original neutral zone concept was first presented by Sir Wilfred Fish in 1931. Since then, several other authors have promoted the development of the concept. However, the techniques are different from the conventional way and are not familiar to most dentists. With the original neutral zone approach to complete dentures, the procedure is reversed. The advantages of the neutral zone concept are the occlusal rims and then the denture teeth were placed in the area so called “neutral zone” that the forces from lips, tongue and cheeks were neutralized during function. The result is the stable denture with good fit, comfort and that always stay in place which causes better patient’s acceptance. The complete denture fabricated on severely resorbed mandibular edentulous ridge always has the problems about stability, fit and retention. The modified neutral zone approach offers an alternative way to the dentists to get better results, and the techniques are not much different from the conventional way of approaches.
The purpose of this article is to present an alternative approach to complete denture over the severely resorbed mandibular edentulous ridge to overcome the stability and fit problems.
1. The techniques to obtain study casts, and master casts are the same as the conventional approaches.
2. The baseplates may incorporate wire loops to provide better retention to the compound occlusion rims, or sticky wax can be use for this purpose.
3. The baseplates must be very carefully examined and adjusted intraorally to be sure that they are not overextended and that they are stable during opening, swallowing and speaking.
4. The upper occlusion rim was fabricated with pink baseplate wax. The contour and occlusal plane were corrected following the conventional guideline.
5. Modeling compound was softened in a water bath, then kneaded, rolled and adapted on the lower baseplate.
6. The baseplate with softened compound occlusion rim was carefully rotated into the patient’s mouth. Fingers were placed on both sides of the base to help stable the baseplate at the beginning of the neutral zone molding. The patient then was instructed to suck and swallow while molding the compound. The compound occlusion rim was roughly reduced the height occlusally, then was softened and molded repeatedly until minor changes on compound was noticed. The green stick compound was used to correct the void and defect of the compound occlusion rim.
7. The occlusal height and plane of the compound occlusion rim then were adjusted following the conventional guideline, from the angle of the mouth to the level of two-third of the retromolar pad.
8. The vertical dimension then was verified and the centric relation was registered. Then, the master casts were mounted on the articulator.
9. The buccal and lingual indexes of the lower occlusion rim were made using silicone putty to preserve the outer and inner contour of the compound occlusion rim. Then the compound was removed and the denture teeth were set following the silicone indexes regardless of the position of the alveolar ridge crest.
10. The contour of the wax trial denture must conform to the contour of the silicone indexes both buccally and lingually.
11. The maxillary denture teeth set up and the complete denture occlusion were followed the conventional guideline.
12. After completion of the denture teeth set up, the wax trial dentures were tried in the patient’s mouth and checked for patient acceptance, then the wax trial dentures were flasked and processed. The finished dentures were then delivered to the patient and adjusted conventionally.
The keys to success for this technique involve two factors; creating the stable base and manipulation of the compound. The compound must be very securely attached to the base and must be thoroughly and uniformly softened while molding but the compound must be hard enough to maintain its shape while handling. Manipulation of the compound needs some skills and experiences that could be a problem when trying the technique for the first time. Also, because the occlusion rim has to be fabricated and molded intraorally, there will be more chairside-time consuming. However, these two disadvantages could be diminished when mastering the technique.
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