Chapter 14 Provisional restorations
During the time period between tooth preparation and fit of an indirect restoration it is important in most situations to provide a patient with a high-quality provisional restoration. Failure to do so could lead to the early demise of the definitive restoration for reasons which will be outlined in this chapter. This comes at great expense to both patient and dentist, in terms of both monetary and biological cost, and professional relationship and trust.
Some may argue, why waste precious time crafting a bespoke provisional restoration only for it to be replaced within weeks? Moreover, the cynic would argue that acceptance of the definitive restoration can be problematic if the dental aesthetic and function of the provisional restoration is comparable to that of the final restoration. To the contrary, when the dentist appreciates the relationship between form and function of a provisional restoration and its relationship to the immediate and long-term health of the teeth, supporting structures and the definitive restoration, its importance is unquestioning; the dentist/health care professional now only has to acquire the knowledge and skills to construct one.
Oral health care and treatment planning for advanced operative procedures follows a logical sequence as outlined in the earlier chapters of this textbook: initially stabilizing (including preventing further) dental diseases, evidence of oral health and then the possible reconstruction of teeth. The success of each stage of management depends upon the success of the preceding stage. The same is true when providing laboratory-fabricated indirect restorations. It is unacceptable to provide a laboratory-fabricated restoration without the prior placement of a provisional restoration. Whilst it is true that a less than ideal provisional restoration might not always influence long-term outcome of the definitive restoration, it may result in a lengthy ‘fit appointment’. A health care professional would not be discharging their responsibility if any aspect of their treatment is substandard, including the placement of provisional restorations. The synergy between an empowered patient, dentist and dental technician can and should provide a seamless continuum of dental care and provisional restorations are a part of this.
With respect to terminology, there is a facile debate as to whether or not such restorations should be called provisional or temporary. The debate is perhaps academic and in this section they will be referred to as provisional restorations.
When considering provisional restorations it is most logical to consider features that must be achieved and then other ‘value-added’ functions of the restoration. Before exploring these, at the centre of every carer’s ethic is ‘Primum nil nocere’ (First, do no harm). Preparing a tooth for a laboratory-fabricated restoration will, however, by necessity:
A provisional restoration should therefore restore the characteristics that have been lost and additionally allow optimum home care. ‘First, do no harm’ also applies to something seemingly as trivial as providing a provisional restoration. Consider the provisional crowns provided in Figures 14.1 and 14.2. The provisional restoration in Figure 14.1 demonstrates an adequate fit cervically and home care should therefore not be compromised. In contrast, the provisional restoration that has been placed on the molar tooth in Figure 14.2 had overhanging margins and during the short time in situ adequate oral hygiene has not been possible and gingival inflammation has ensued.
Figure 14.2 A poorly fitting provisional crown has been removed from the upper left first molar tooth. The overhanging margins mesially and palatally have prevented adequate home care with resultant plaque accumulation and gingival inflammation.
Provisional restorations can be either custom-formed to each individual situation or preformed by manufacturers in standard shapes and sizes and adjusted to fit at the chairside. The custom-formed temporaries are preferred, but are perhaps a more demanding technique to master.
The most appropriate material to be used for a custom-formed resin replica provisional restoration is a chemically cured bis-acrylic composite resin, for example Protemp Plus Temporisation Material (3M ESPE) or Integrity TempGrip Temporary Crown and Bridge Material (Dentsply). The merit of using this as a provisional restorative material is that it can be customized so that its internal aspect custom fits the preparation and its external surface reproduces accurate contact points and occlusion with the opposing arch.
It is important that the provisional restoration is made before the impression is taken. This is because the provisional restoration can be used to affirm that the tooth preparation characteristics are satisfactory. These include whether sufficient tooth/core has been prepared to accommodate the definitive restoration (Figure 14.3) and other preparation characteristics such as whether the preparation is undercut or not (Figures 14.4 and 14.5). If deficiencies in the preparation are found these can be remedied and the temporary can be relined or remade. An impression of the preparation can now be made with reassurance that the preparation is satisfactory.
Figure 14.3 An Iwanson gauge can be used to measure the thickness of the provisional restoration in relation to the buccal cusp occlusal reduction, for example. If it is shown that there is insufficient tooth reduction, further preparation is carried out and the provisional restoration is relined.
Figure 14.4 Bis-acrylic composite provisional restoration, affirming a satisfactory preparation for a gold overlay. This provisional restoration shows mesial and distal gingival bevels to the proximal box preparation.
Firstly a sectional impression of the tooth to be prepared is made. A full arch impression is unnecessary for this and would make it more difficult to relocate on the teeth. This can be done in a number of materials: