Читать книгу Removable Prosthodontics at a Glance - James Field - Страница 11
Оглавление5 Edentulous ridge presentations
The photographs opposite show a range of edentulous ridge presentations. Whilst the range shown is by no means exhaustive, each photograph presents a number of interesting points for consideration when planning a removable prosthesis.
Upper edentulous ridges
Photograph 1
Intraoral access here is good and the full denture-bearing area (DBA) can be palpated without any pain or gagging. The mucosa looks moist and there are no signs clinically of a dry mouth. The ridge is well formed with high and rounded ridges – and this would be classified as Class III (Cawood and Howell). A retained root has recently been extracted from the UL5 and this presents as a crestal defect. The prominent incisive papilla is erythematous and this is a sign that it may need a degree of relief in order to prevent recurrent trauma. There is a slight buccal defect to the ridge on the left-hand side and the muscle attachment here inserts into the base of the sulcus. Paradoxically it can be easier to account for high muscle insertions than lower ones – and so this area would receive particular attention during the working impression. It is possible to see the posterior extent of the existing denture, which is short of the fovea palatini by at least 10 mm. It is also possible to see the limited degree to which the denture base wraps around the tuberosity on the right-hand side – and this can be improved during the working impression with a border moulding material to ensure that its full anatomy is captured.
Photograph 2
Intraoral access here is slightly restricted. The full DBA can be palpated without pain or gagging. The mucosa looks shiny and dry, and clinically there are signs of a dry mouth; the mirrors stick to the mucosa, and food debris accumulates at the denture borders. It may be necessary for the patient to consider a saliva substitute in order to promote effective adhesion and cohesion, and a border seal. The ridge is well defined and rounded (Class III), but the sulcal depth reduces significantly towards the posterior aspects. The palate is relatively shallow and broad – shallow ridges and a shallow palate mean that the denture may have a compromised stability. The muscle attachments insert onto the crest of the ridge – this is the other extreme of how attachments may present. The challenge here is ensuring they are accommodated for, without compromising the border seal. The labial portion of the anterior ridge presents with a significant undercut and it is worth considering at the assessment stage whether a defined path of insertion is possible, or whether the permanent base should be modified with permanent soft liner to allow the ridge to be atraumatically engaged.
Photograph 3
Intraoral access here is excellent. Palpation of the DBA in the palate beyond the posterior border of the existing prosthesis results in a gag reflex. There is no pain on palpation. The ridge is well formed (Class III) but lacks some definition in the premolar regions, where it presents with a knife edge (Class IV). Once again, muscle attachments are situated near the base of the sulcus, so attention to detail during the working impression will be important. It is possible to see the posterior extent of the existing denture, which is short by at least 15 mm. It is also possible to see the limited degree to which the denture base wraps around the tuberosities. Both of these features will significantly compromise the stability and retention, and perpetuate the gag reflex. A thin band of tissue exists along the crest of the ridge from incisor to premolar on the patient's right-hand side, and this should be accounted for in the working impression; in order to avoid the denture ‘nipping’ the tissues, the impression should be taken in zinc oxide eugenol, and the borders of the thin tissue ridge should be filleted away with a scalpel. Once again, the labial portion of the anterior ridge presents with a significant undercut and it is worth considering at the assessment stage whether a defined path of insertion is possible, or whether the permanent base should be modified with permanent soft liner to allow the ridge to be atraumatically engaged.
Lower edentulous ridges
Photograph 4
The full DBA can be palpated without any pain, although contact with the posterior lateral borders of the tongue elicits a gag reflex. The ridge is atrophic with a knife edge presentation (Class IV). A thin fibrous band of tissue runs along the entire crest of the ridge – and this should be accounted for in the working impression; in order to avoid the denture ‘nipping’ the tissues, the impression should be taken in zinc oxide eugenol, and the borders of the thin tissue ridge should be filleted away with a scalpel. Muscle attachments are low and there is only a moderate sulcal depth anteriorly when the lip is retracted. The tray will need to be carefully adjusted here to ensure it is not overextended.
Photograph 5
The full DBA can be palpated here without eliciting pain or a gag reflex. The tissues are fibrous anteriorly, and it is possible to see the folds of tissue in the photograph. The ridge is atrophic (Class V) but presents with an identifiable fibrous crest. This is thicker than in photograph 4, and so is unlikely to fold over when the denture is seated. No special interventions are required in that regard. There is little identifiable sulcus anteriorly and so the tray will need to be carefully adjusted here – and it may even be the case that a purposefully mucostatic or mucocompressive impression (depending on the assessment) is taken to account for the anterior fibrous tissue. Ulceration is visible in the buccal and labial sulci, and it is important to ensure that this is resolved prior to working impressions.
Photograph 6
The full DBA can be palpated without pain or gagging. The ridge is firm, well formed and generally rounded at the crest – although there are undercut aspects around the buccal aspect. This would be graded as Class IV. Muscle attachments are relatively low and there appears to be a reasonable depth to the labial sulcus. Avoid thinking that these cases are straightforward to treat – it is sometimes the case with well-formed ridges that they pose problems in terms of ridge pain after fitting of the dentures.
