Article
When providing a patient with new complete dentures, the clinician may use a conventional or replica record block (‘copy’1) technique. Particularly with long-serving dentures, the patient will have become accustomed to the shape of the prostheses, and have developed muscular control accordingly. Marked differences in the form of subsequent dentures may lead to difficulties in tolerance and control, which can be minimized by the use of the replica denture technique. This technique has the following well-recognized indications:2
In conventional denture construction, the primary impressions should aim to represent the full denture-bearing area,3 in order to facilitate the later stages of construction adequately. The authors feel that this same principle should apply to the initial stage of replica denture-making. Here, the modification of peripheral extension of a denture is made prior to the first stage of the replica technique, rather than during the later stages.
Clinical technique
An assessment of the existing dentures in relation to the denture-bearing tissues should be made to assess the adequacy of the extension fully and identify areas of deficiency.
The existing dentures can be modified with greenstick (low fusing) compound prior to making an impression of the dentures in silicone putty,2 using a similar technique to the modification of a special tray in impression-making for conventional dentures.
Greenstick compound should be heated gradually to soften it without becoming too flowable. The material can be heated over a Bunsen burner or using a hot-air device, with frequent removal from the heat source to allow the heat to dissipate throughout the material; although the authors use a hot water bath to soften greenstick to a consistency which allows easy manipulation. A thin coating of petroleum jelly on the clinician's gloves prevents the material from sticking to the fingers and allows easier manipulation.
The material may then be added to appropriate areas of the denture prior to insertion into the mouth (Figure 1) for border moulding as for impression-making. The modified denture can be re-heated in the water bath to allow further manipulation of the greenstick, as necessary.
It is useful when modifying the posterior maxillary buccal sulci to ask the patient to close halfway and move their chin from side to side, to record the width of the sulci and prevent interference of the denture flanges with the coronoid processes of the mandible.
Following satisfactory modification of the dentures (Figure 2), the replica impressions of the dentures can be made in silicone putty as normal. The greenstick can then be easily removed prior to returning the denture to the patient.
This technique may also be used where greater modification of the denture base is required; for example, the addition of a flange to an open-faced denture.
The authors have also used this technique in further extension of the maxillary denture base adjacent to a lone molar (Figure 3). This particular case was in the construction of a replica obturator for an elderly patient with cleft palate.
Conclusion
The assessment and modification of the borders of a complete denture with greenstick compound prior to the first stage of a replica technique will facilitate the construction of a well-extended, well-retained final denture.