APPROACHES TO TREATMENT OPTION THREE
It is hoped that with more effective preventive dentistry and treatment, the need for this approach will decline with the passage of time.
- Advanced untreatable periodontitis.
- Advanced caries, particularly when affecting roots subosseously.
- The above, and untreatable endodontic problems.
- The above, and financial constraints on retreating.
- Extensive failure of an implant prosthesis (either subperiosteal, endosteal or transosteal) leading to insufficient residual bone for a new implant, or to the patient being unwilling to be retreated with implants.
- Severe aesthetic problems necessitating provision of ‘plastic gingivae’.
- No desire (disinterest) by the patient for extensive retreatment.
- As an interim stage, when osseointegrated fixtures are to be used.
- Medical conditions such as:
– Terminal disease, making extensive retreatment untenable.
– Heart defects, making oral infection potentially life-threatening. Particularly if there is a previous history of infective endocarditis.
– Those whose treatment is so debilitating as to make extensive retreatment untenable.
When the Existing Restoration can only be Removed in its Entirety, for Example, a Full Arch Fixed Bridge which if Divided would be Unusable (Fig 30-1a)
- Ensure that the patient understands beyond any doubt that all the teeth are to be extracted.
- Ensure there are no medical contraindications or, if present, that the appropriate medication is given.
- Make upper and lower alginate impressions and pour casts.
1) If CRCP and the IP do not coincide, consider making an occlusal stabilization appliance to establish the madibulo/maxillary relationships before the teeth are extracted. It is easier to establish the relationships with an appliance anchored to a stable base of teeth, than with a complete denture supported by alveolus.
2) Fabricate a special tray (Fig 30-1b) for the palate and edentulous areas and the periphery of the upper arch, together with an overtray to take an elastomeric impression of the remaining teeth and to pick up the first tray. If, however, hydrocolloid is used for the pickup impression, a stock tray is used as the overtray. Prepare similar trays for the lower arch.
3) Modify the periphery of the undertray (Fig 30-1b). Try the tray in the mouth and hold it in place. It is important to have vertical stops against the palate in the upper jaw, or occlusal surfaces in the lower. Manipulate the muscle attachments and cut away any overextended parts of the tray. These are usually directly visible, but when this is not the case, it may require the application of pressure relief cream (Mizzy – Kerr) for identification. Reduce, with an acrylic trimmer, the periphery of the tray by approximately 2 mm. Then extend it with greenstick compound (Fig 30-1b) or peripheral seal (De Trey Co.); of the two, greenstick compound is easier to control, it is used as follows:
The tray is dried and the compound is heated in a hot air heater; it is rotated whilst being heated until just soft. The softened compound is added in ‘a painting manner’ to the periphery on one side and, with the gloved hand lubricated with Vaseline, lightly moulded to adhere to the tray. The compound on the tray is then resoftened in the hot air and the tray dipped in a water bath at 55 °C and placed in the mouth, it is held in place against the vertical stops. The border is moulded and further compound added to the other side to obtain full border moulding. The compound is then chilled in iced water.
Zinc oxide eugenol impression paste (SS White) is mixed and added along the periphery of the special tray and to the palate on the upper and any edentulous areas. The tray is seated and border moulded once again. It is then removed and checked for marginal integrity (Fig 30-1c).
4) A pick-up impression is then made with the overtray or, if hydrocolloid is to be used, with a stock metal tray. When using a stock tray a roll of wax (Moyco Extrahard Beauty Wax) is softened at 55 °C and applied to the centre of the palate of the upper tray and to three strategic places around the lower tray (Fig 30-1d). The tray is seated over the under tray and removed and chilled. These wax stops later assist in stabilizing the under tray during the pick-up procedure. The pickup impression is made (Fig 30-1e).
5) The pick-up impression is trimmed peripherally to expose the periphery of the zinc oxide eugenol impression (Fig 30-1e). The softness of hydrocolloid makes it particularly easy to trim.