Mouth preparation for complete dentures

Denture hyperplasia

The clinical picture of denture-induced hyperplasia can be described as one or more folds of hyperplastic tissue induced by trauma from the border of the denture. Ulceration may be present between the folds. The lesions can originate in a narrow fibrous stem or, alternatively, have a broad base. Denture-induced hyperplasia is present in 3% of the denture-wearing population.¹

In the maxilla, this type of lesion is described as a cauliflower-like tissue that may occur under, or at the edge of the denture (Figure 1). Commonly, it occurs when constructing immediate dentures or in those who have worn dentures for a longer period of time (ie more than 5 years).^1,2 Bone resorption allows a space to form inside the flange of the denture over time, and the ill-fitting denture irritates the soft tissues. This in turn stimulates the soft tissues to grow down into the space inside the denture. Over time, the tissues enlarge and congregate outside the denture flange.²

Treatment would include generously reducing the flange by at least 1 mm free of the lesion. This may be combined with a soft or hard reline of the denture. Alternatively, the patient should be advised to stop wearing the denture until (some) regression of the lesion is noted.^1,2 It is thought that the time required for severely hyperplastic tissues to return to normal is about the same as that required for the lesion to develop. However, some lesions do not resolve and will require surgical removal.^1,2

Mandibular hyperplastic lesions are described as a roll of fibrous tissue (Figure 2). Folds of hyperplastic tissue may be situated inside and outside the denture flange.² They are managed in a similar manner to maxillary hyperplasia.

Denture stomatitis

Denture stomatitis may vary in its clinical presentation and is classified as follows:³

The prevalence of denture stomatitis is estimated to range between 15% and 77.5% of the denture-wearing population and is mainly found in the maxilla.⁴ Most cases would be classified as Newton Type I and II. Its origin is thought to be multi-factorial and could be due to one or a combination of factors (Table 2).⁵ Associations have been made with micro-organisms, with the main focus on Candida albicans; however, Staphylococcus aureus, Pseudomonas aeruginosa, C. glabrata, Prevotella spp, Veillonella spp and others are now considered to be of interest in relation to progression of the condition.⁵ It is accepted that the most common aetiological factor of denture stomatitis is unsatisfactory denture hygiene. One study demonstrated that the incidence of severe inflammation and hyperplasia is 10 times greater among those who sleep with their dentures.^4,5 Despite denture-wearing patients being aware of the potential risks of not removing the dentures at night, a proportion will not comply for reasons of self esteem and social implications.

It would be unwise to start impression taking and denture construction before the denture stomatitis has been treated. Inflammation of the denture-bearing area will inevitably lead to inaccurate master casts and therefore, a suboptimal fit of the dentures.

Not surprisingly, the first line of treatment is to remove the dentures at night and improve overall denture hygiene. The application of coatings such as nanopolymers (eg GC Optiglaze, GC, Europe) or nanosilica to the dentures reduces surface roughness and inhibits biofilm formation.⁵ Once denture stomatitis is established, it is suggested that disinfection of the dentures will be as effective as using antifungals.⁵ A 0.002% sodium hypochlorite solution (available in the UK from local chemists as Milton's solution) used for 15 minutes has been proven to reduce the fungal load on acrylic surfaces. Chlorhexidine 2% would be an alternative; however, disinfection may produce staining with prolonged use.³

For patients with underlying medical conditions and/or where local measures do not resolve the denture stomatitis, antifungal agents may be prescribed. Miconazole oral gel 24 mg/ml applied four times daily is a topical agent for the fit surface of the dentures. Caution should be taken when prescribing for patients on warfarin as there is a well-recognized drug interaction. Fluconazole and nystatin oral suspension are systemic fungal agents that can be considered in more severe cases.³ For a small number of patients, the condition will develop to Newton Type III, and they will present with papillary hyperplasia, which is more challenging to treat. Surgery may be indicated and an oral surgery opinion will be required.⁴

Traumatic ulcerative lesions

They are commonly caused by over-extended or ill-fitting dentures. The dentures could be new dentures or dentures that are several years old. An over-extended denture flange will cut through the mucosa and invade the underlying submucosa and muscle tissue.² When the extension has been corrected, the lesion will heal with formation of scar tissue. Without denture adjustment this could lead to the formation of denture hyperplasia.

Recurrent aphthous stomatitis (RAS)

Recurrent aphthous ulcers are commonly encountered by general dental practitioners. They are recurrent oral ulcers that present in otherwise healthy individuals.⁶

Three forms of RAS exist: minor (>70% of cases), major (10%) and herpetiform (10%). These types differ in their morphology, distribution, severity and prognosis (Table 3).⁶ Treatment usually depends on the severity of the condition. It starts with topical treatments, such as chlorhexidine 0.2% mouthwash, which helps in preventing secondary infections. Temporary relief can be achieved using topical anaesthetic preparations that contain benzydamine hydrochloride or lidocaine.⁶ Topical steroids, such as betamethasone 5 μg soluble tablets as a mouth wash, fluticasone propionate spray or mouthwash, may also be used.⁶ Long-term use of topical steroid preparations carries a risk of oral candidiasis.⁷ For severe cases of RAS, appropriate referral to an oral medicine clinic will be required because systemic medications might be necessary. Systemic treatments include systemic steroids, immunosuppressants, and other types of medication such as dapsone, thalidomide and colchicine.⁷

Oral lichen planus

Oral lichen planus (OLP) is a chronic mucocutaneous disorder that can affect the skin as well as the oral mucosa (Figure 4). It can also affect the lips, nails, scalp and other mucosal surfaces. Approximately 1–4% of the general population is affected. It is more common in middle-aged women, but rare in children.⁸

Oral lichenoid reactions are usually caused by the use of systemic medications, for example antihypertensives, oral hypoglycaemics and non-steroidal anti-inflammatory drugs. It can also occur in relation to amalgam restorations or other dental materials, such as composites or glass ionomer.⁸

OLP presents clinically as reticular, papular, erosive, plaque-like, ulcerative or bullous lesions.⁸ Treatment depends on the severity of the disease, starting with topical anaesthetic and topical steroid preparations. For more severe cases appropriate referral to an oral medicine clinic is needed to discuss further treatment options, including systemic steroids and steroid-sparing medications.^8,9

Severe OLP could impact on denture success if not treated or managed successfully prior to denture construction. Modification of the treatment plan is frequently indicated.

Traditional removable dentures can be difficult to tolerate for patients with OLP because of the fragility of the oral mucosa. Ill-fitting dentures can lead to trauma, which can exacerbate oral lesions and lead to ulcerations or erosions.¹⁰ Implant-supported prosthetic devices may stabilize prostheses and minimize trauma to the oral mucosa, thus improving denture function and patients' quality of life.¹⁰ Li et al described a case of severe OLP in which implant-retained over dentures were used.¹⁰

Oral cancer

Although oral cancer is a relatively rare condition, it should be highlighted. In the UK, head and neck cancers contribute to 3% of all cancer cases.¹¹ Most are diagnosed as squamous cell carcinomas (Figure 5). Risk factors include tobacco consumption and excessive alcohol consumption.⁶ Oral cancer most commonly presents as a non-healing ulcer, white patches or erythematous lesions. Patients may also present with increased tooth mobility, bleeding, numbness or pain.⁶

Patients with suspicious lesions should be referred urgently as appropriate for an oral medicine or oral surgery opinion.

Excessive large undercuts and bony exostoses

Most bony undercuts will not require any surgical intervention. They may be blocked out by the laboratory before the processing of the denture. Usually, tinfoil relief can be added onto the master cast to ensure there is spacing between the processed denture base and the affected denture-bearing area. This in turn will limit friction during function. Large bony undercuts can often be left on one side and surgically corrected on the opposite side. Dentures can engage some degree of undercut because the hard, bony tissues are covered with a layer of soft tissue that allows for some degree of compression. Undercuts will aid in retention, and might be beneficial for denture-wearing comfort during function. Surgical bony reductions in the anterior segment should only be carried out for extreme undercuts, and it is known that healing after surgery is not always predictable.¹² Patients should be informed that reoccurrence of the bony interference is possible and/or that removal may not always address all problems.

Tori

Tori are bony enlargements that are considered anatomical variations and are not pathological. The aetiology is considered to be multifactorial with genetics and environmental factors playing a role in their formation.¹³ They occur on the midline of the hard palate in the maxilla and often bilaterally on the lingual aspect of the mandible where they are most frequently located in the canine area.¹²

Mandibular tori (Figure 6) are found in up to 64% of different population groups. Tissue covering these tori is often delicate and thin. Frequently tori extend into the region of the lingual functional sulcus depth and therefore may need to be removed.^12,13 Maxillary tori (Figure 7) are found in up to 61.7% of different population groups.^12,13

Palatal tori are only removed if they are excessively undercut or in certain situations where they extend onto the vibrating line. Tinfoil relief or arbitrary removal of acrylic on the denture fitting surface should be undertaken to prevent pain and instability during function. Unadjusted dentures in these areas might lead to fracture lines or complete fractures of the denture.

Enlarged tuberosities

Enlarged fibrous tuberosities are suboptimal in providing support. They also limit the inter-arch clearance and there may only be sufficient space for one denture.¹⁴ If the patient prefers to wear a denture in the upper jaw, it could lead to damage to the lower edentulous ridge. Similarly, if the patient prefers to wear a denture in the opposing jaw, the tuberosities can be traumatized continuously, which may be uncomfortable and distressing for patients. To partially overcome the issues with space, the teeth will need to be set up towards the buccal aspect of the tuberosity. Alternatively, to create space for a denture, the tuberosities may be surgically reduced if the anatomy of the sinus allows for this procedure to be undertaken. Another solution would be to construct a denture under-extended towards the vibrating line (avoiding the tuberosity/tuberosities); however, retention will most likely be suboptimal.

Flabby ridges

Fibrous ridges can be defined as edentulous ridges of a displaceable nature. The bony tissue will have been replaced with tissue of a more fibrous nature, which provides suboptimal support and may lead to problems with retention.

Flabby ridges can be found in up to 24% of patients with an edentulous maxilla, and up to 5% of patients with an edentulous mandible.¹⁴ Several techniques have been suggested to deal with this problem, including the selective pressure impression technique and the minimally displacive technique.^14,15 Surgery has fallen out of favour because many patients who present with this problem are elderly and have complex medical issues where invasive procedures should be minimized. In addition, the excision of these tissues will reduce the ridge height to an extent where little resistance to lateral forces can be expected. Often retention will also adversely be affected.¹⁴