Article
The prevalence of edentulous patients has decreased in Western society. The Adult Dental Health Survey determined that the level of edentulism reduced from 13% to 6% between 1998 and 2009.1 There appears to be a changing pattern in oral health status as patients are retaining their natural teeth for longer, meaning that dentists are no longer making the same number of complete dentures as our predecessors, and may be becoming deskilled. Therefore, when faced with complex patients requiring complete denture construction, dentists may feel out of their comfort zone and in need of improved knowledge and skills.
Microstomia describes a reduction of oral aperture,2 which may be congenital or acquired. It may be a consequence of conditions including post-surgical and radiotherapy, trismus, cleft lip and palate, trauma, scleroderma, temporomandibular joint disorder, Plummer-Vinson's syndrome, oral submucous fibrosis or damage to the muscles of mastication.3 Microstomia makes all dental treatment more difficult, especially during prosthodontic impression taking, and prosthesis construction may even be rendered impossible. Alternative techniques include modifications to small stock trays by sectioning, or using children's stock trays.4
This report describes the prosthetic management of a patient suffering from extensive post-surgical circumoral stenosis and acquired microstomia which rendered denture construction extremely challenging. An innovative strategy was required for recording primary impressions, when the smallest stock trays available were too large to fit intra-orally. Impression compound was adapted to an articulator bite fork to record a primary upper impression.
Case report
A 75-year-old female attended as a new patient requesting upper and lower complete dentures. Her expectations of treatment were the restoration of function and aesthetics and reduction of saliva drooling.
The patient had an initial diagnosis of a basal cell carcinoma (BCC) at the inner canthus of her right eye 22 years previously. This was surgically removed, eliminating her tear duct. Over the next 20 years she experienced not only a recurrence of the original BCC, but also a further 11 BCCs affecting both right and left temples, lips, neck, back and legs. On each occasion she underwent surgery to remove the BCC. In November 2014, she was diagnosed with 11 BCCs simultaneously, and underwent 7 months of chemotherapy. In August 2015, she underwent further facial surgery. She is a life-long non-smoker, rarely drinks alcohol and had no other relevant medical history or history of excessive sun exposure to account for the numerous BCCs. After further consideration of the patient's unexplained multiple BCCs, perhaps this is a case of Gorlin-Goltz syndrome. Gorlin-Goltz syndrome is also known as Nevoid Basal Cell Carcinoma syndrome and comprises a rare genetic predisposition to BCCs.5
The patient had been edentulous for several decades, with a history of wearing complete dentures. However, she was unable to wear dentures since her initial surgery in 2014 as her microstomia meant she was unable to insert them.
On examination, extra-orally, she had post-surgical oral stenosis, deficient nasal septum and incompetent lips (Figure 1). Intra-orally she was edentulous with acquired microstomia. The maximum vertical mouth opening was measured to be 22 mm (Figure 2), compared to the average maximum mouth opening of 41 mm for females.4Figure 3 shows the patient's atrophic lower alveolar ridge and labial sulcus.
On attempting to record primary impressions, even the smallest stock tray available was too large for her mouth. Impression compound was subsequently adapted around the bite fork of an articulator and was successfully used to record a preliminary impression. Functional extension of the compound was defined in the sulci by gentle border moulding as the soft tissues were very tender. Border moulding was challenging due to severe fibrosis. Impression compound was preferable to alginate due to improved control of flow and ability to make minor adjustments. The impression consisted of multiple placement of compound with selective warming to pick up detail and correct errors. The metal bite fork held heat and consequently the compound remained fluid (malleable) for longer. It needed to be in the mouth for longer to cool and become firm. Also the fork provided a base but no lateral support, so border moulding was more complex than with a stock tray. In terms of inserting the bite fork into the patient's mouth, one arm was placed in, then the other was rotated in to try to avoid lip contact that would cause a distortion in the compound. Figure 4 shows the primary casts that were constructed from the primary impressions.
The laboratory subsequently constructed upper and lower close-fitting special trays and major impressions were recorded using greenstick compound and zinc oxide eugenol. The remainder of treatment followed the usual stages and the patient was fitted with dentures.
Given the patient's post-surgical stenosis, atrophic maxilla and atrophic labial sulcus, a Class III incisor relationship was deemed most appropriate. At try-in, the upper centre-line matched the midline of her nasal philtrum. Given the patient's asymmetrical face, it was felt to be more appropriate to adjust the centre-line to match the LL1–LL2, rather than LL1–LR1, in order to improve the overall aesthetics of the dentures. At the next try-in, the patient expressed high approval with both the fit and aesthetics of these dentures, so the fitting proceeded. After the fit stage, the patient remained very pleased, vocalizing that the dentures had greatly improved her aesthetics. The patient was reviewed after one month and a small part of the lower denture was eased anteriorly coinciding with an area of gingival hyperplasia.
The patient was last reviewed nine months later and reported no problems apart from a recurrence of BCC (Figure 5). Overall, she was very satisfied with the aesthetic and functional result and reported an improved quality of life. However, she also reported that her BCC has returned, and she is awaiting a further course of chemotherapy.
Discussion
This case highlights the difficulties in managing patients with microstomia. Microstomia can cause difficulties during every stage of prosthetic construction. It was decided to use the bite fork compound technique; an alternative technique would have been to use sectional trays to create a preliminary impression. However, this technique poses the challenge involved in relocating the sectional trays outside the mouth.6 In severe cases of microstomia, patients can struggle with the relatively simple tasks of denture insertion and removal. In this case, the patient suffered from transient discomfort when stretching her skin on insertion and removal of impressions, registration blocks and the final dentures.
This was a challenging prosthodontic case, given that the smallest stock impression tray was too large to fit intra-orally. It was eventually decided that the only option, aside from a split tray technique, was to use the bite fork innovatively from an articulator with impression compound to construct a unique preliminary impression tray which was suitable for this patient. This worked well and consideration of this technique is recommended when a similar situation is encountered.
After further consideration of the patient's unexplained multiple BCC, perhaps this is a case of Gorlin-Goltz syndrome.
Conclusion
With the challenges associated with microstomia, it is important to use resources already available innovatively to treat these patients, and ultimately provide satisfactory dentures. This technique is both a practical and inexpensive solution, attractive in modern dentistry as it may improve both quality of patient care and cost-effectiveness. We therefore suggest that, in cases where small stock trays are too large to fit in patients' mouths, this compound and bite fork technique is considered to construct special trays.