Encourages a straight back
Improves interarch visibility for assessing occlusal relationships, facial aesthetics and speech
Control of the prostheses and trays
It is very important that you take control of inserting and removing impression trays, and the patient's prostheses. When you insert and remove prostheses, you are able to look closely at the way in which the extensions and fitting surface engage with the tissues, and check paths of insertion. You are also able to apply appropriate pressure to certain areas in order to check stability or painful trigger points. If the patient continually removes and inserts their prostheses, then they often take the opportunity to displace them in fairly imaginative ways – and it is these parafunctional habits that you will spend much of your time counselling them against. Further, in relation to impressions – never leave an impression in the patient's mouth without being in full control. This means not letting go and performing another task – and handles are critically important in ensuring control, tray orientation and efficient and effective removal.
Other considerations
Restricted access might mean that you need to use a syringe to deliver material onto the denture-bearing anatomy and then insert the tray as the carrier. When rotating trays into the mouth, it is useful to ask the patient to ‘half close’ – and applying Vaseline to the corners of the mouth can avoid trauma to friable tissues.
9 Pre-prosthetic treatment
When embarking upon the provision of removable prostheses, it is important to assess the patient's oral environment comprehensively. Achieving a stable foundation is the bedrock upon which successful rehabilitation will be built. Castles cannot be built on sand. Pre-prosthetic treatment involves the care that is delivered prior to the planning and delivery of prostheses (Figure 9.1). This may involve:
Management of acute pain/sepsis
Stabilisation of any active oral disease including periodontal disease, caries, soft tissue conditions and neoplasia
Surgical modification of hard and soft tissues to facilitate retention and/or stability of the prosthesis
Extraoral assessment
A careful extraoral assessment can reveal the following features, which may impact on how and when you provide prosthetic rehabilitation:
Facial asymmetries
Skeletal class
Restrictions or trismus
Hypertrophy of muscles of mastication
Degree of mobility and dexterity
Edentulous patients
Where the fully edentulous patient is concerned, the condition of the soft tissues should be assessed and the architecture of the bony hard and overlying soft tissues noted. This was discussed in Chapter 4 – however, it is important to note that significant undercuts, tori, or fibrous tissue may benefit from pre-prosthetic surgery. It may also be the case that muscle attachments may need repositioning, vestibules surgically deepened, sharp ridges smoothed, keratinised tissues augmented and previous surgical sites debulked. The latter are often carried out in conjunction with oral surgeons – and any pre-prosthetic surgery will need to be consented and planned appropriately, with a suitable period of healing prior to provision of the definitive prosthesis. Consideration should be given for how the patient will manage in the interim, either without a prosthesis in place, or by making modifications to existing ones.
Partially dentate patients
Where the partially dentate patient is concerned, additional observations must be made around the condition of the remaining dentition including:
Active dental disease (plaque control, caries and periodontal health)
Type of occlusion including any evidence of bruxism or parafunction
Limitations caused by drifted, overerupted and tilted teeth
Endodontic status of teeth
Status of any existing direct or indirect restorations
Periodontal disease and caries
Where teeth have been lost because of periodontal disease, a thorough assessment of periodontal health including a basic periodontal examination (BPE) should be carried out. When a code 3 or 4 presents, a personalised prevention programme should be instigated and suitably demonstrated by the clinician. If a code 4 persists (pocketing above 5.5 mm after plaque control has been optimised and superficial inflammation resolved), then full mouth 6-point pocket charting should be completed. For persistent deep and bleeding pockets, a course of non-surgical management should be undertaken, supported by regular full mouth disclosed plaque and bleeding scores. Subgingival instrumentation should utilise local anaesthesia to comfortably treat deeper and inflamed periodontal pockets, or where tooth sensitivity causes patient distress. Ultrasonic debridement is recommended for this as an effective and efficient method, whilst preventing excessive cementum removal. The 6-point pocket charting should be reassessed 2–3 months following treatment. Generally, periodontal health may be assumed when bleeding is at fewer than 10% of sites and pocket probing depths are no greater than 4 mm, with no bleeding at the 4 mm deep sites.
During periodontal stabilisation treatment, the patient may need to have teeth extracted that are deemed of hopeless prognosis, especially if they present as lone standing and grade III mobile, have bone loss progressing towards the tooth apex (or a true perio-endo lesion), or have been unresponsive to periodontal treatment. During this stabilisation phase a temporary acrylic denture may need to be provided to restore aesthetics and masticatory function, and to reduce occlusal trauma on remaining tooth units. The prosthesis is likely to be entirely mucosa borne, and so care should be taken with the design to ensure that trauma at the gingival margins because of denture displacement is avoided. The contact points between the saddles and abutment teeth should be cleansable, and the patient should be counselled with respect to plaque control on the denture and on the abutment teeth. Even a well-polished acrylic denture acts as a bacterial reservoir and it is for this reason that in short span rehabilitations, resin-bonded bridgework should be considered as an alternative in order to minimise plaque retention; this clearly depends on the quality of the abutment teeth.
Appropriate prevention with diet counselling, hygiene and fluoride therapy should be instigated where the caries risk is raised. Where conservation work is required, this can also allow for construction of restorations which aid the support and retention of the final removable partial denture. Restorations (both direct and indirect) can be fabricated with rest seats, guide planes, adequate bulbosities and precision elements to aid the success of the denture. Accurate primary impressions and mounted study models are essential planning aids for the prosthetic rehabilitation. Aesthetics can also be assessed and