From Volume 46, Issue 5, May 2019 | Pages 450-461
Systemic sclerosis, although a rare disease, has numerous direct and indirect effects on the oral cavity. This article aims to inform clinicians of the signs and symptoms they may see in patients with the disease and the impact it can have on dental management. The main effect, microstomia, is not just limited to systemic sclerosis, thus the clinical and laboratory techniques described may be helpful when managing other patients with limited mouth opening.
Systemic sclerosis (SSc) is a rare autoimmune disease of unknown aetiology, characterized by excessive deposition of collagen in the skin and multiple internal organs, fibrosis of blood vessels and numerous immunologic abnormalities.1 Its prevalence is estimated at 20 cases per 1 million population, with a predominance in females.2 Also known as scleroderma, the disease can present with a wide clinical picture that varies greatly in severity and prognosis. Clinical forms range from limited cutaneous systemic sclerosis, where there is skin involvement only, to forms where there is severe and often progressive involvement of multiple internal organs, known as diffuse cutaneous systemic sclerosis, and occasionally a fulminant course (fulminant systemic sclerosis).3
CREST syndrome (Calcinosis, Raynaud's disease, oEsophageal dysmotility, Sclerodactyly and Telangiectasia) is an older term used to describe limited cutaneous systemic sclerosis with involvement of the face and neck. Diffuse cutaneous systemic sclerosis refers to skin thickening proximal to the knees and elbows as well as distally, as in limited cutaneous systemic sclerosis, and involvement of the face. Internal organs that are most commonly involved are the gastrointestinal tract, respiratory, renal, cardiovascular, musculoskeletal, endocrine and genito-urinary systems3 (Table 1).
| System | Symptoms |
|---|---|
| Skin |
|
| Vascular |
|
| GI |
|
| Respiratory |
|
| Musculoskeletal |
|
| Cardiovascular |
|
| Renal |
|
| GU |
|
Cutaneous involvement of the orofacial region causes microstomia (small oral orifice), observed in 70–80% of patients, with characteristic peri-oral furrow lines. Deposition of the collagen fibres in the peri-oral tissues results in loss of elasticity and thickening of the skin, ultimately resulting in microstomia. A mask-like appearance is often seen due to the lips becoming thin and rigid. Mouth opening can also be impaired by remodelling of the TMJ capsule.4,5 Limited mouth opening complicates self-performed plaque control, dental treatment and prosthetic rehabilitation, and can also lead to difficulty with mastication. The effects of SSc on the oral and facial musculature may cause difficulty with speech, facial expressions, mastication, and saliva control. Fibrosis of the tongue and/or lingual fraenum may have a further negative effect on speech, mastication, bolus manipulation and saliva control.5
The mucous membranes also undergo collagenous changes and, in addition to poor nutritional intake and vitamin deficiencies, atrophy and ulceration may occur. Ulceration could also be an adverse effect of some of the pharmacological agents used to manage SSc, such as methotrexate, azathioprine and cyclophosphamide. Mucous membranes and extra-oral cutaneous tissue may show telangiectasia (vascular malformations thought to occur secondary to disordered neoangiogenesis).5
Xerostomia is commonly seen in SSc patients, with significant effects, and may be due to fibrosis of the salivary glands themselves or due to Sjögren's syndrome. The detrimental effects of xerostomia on the dentition are well known.5 Combined with reduced oral opening and compromised manual dexterity from fibrosis of the fingers, SSc patients are at particularly high risk of dental caries and periodontal disease (Table 2).
| Orofacial Manifestation | Clinical Features |
|---|---|
| Microstomia |
|
| Mask-like facial appearance |
|
| Mucosal atrophy |
|
| Xerostomia |
|
Prosthetic rehabilitation of a patient with SSc is challenging in its own right but becomes further complicated when Sjögren's Syndrome (SS) is also present.
For the partially dentate or edentulous patient, the stages of denture construction, beginning with impression taking and culminating in delivery of the final prosthesis, represent a challenge. Clinicians must carefully consider their ability to insert and remove impression trays from patients' mouths. Furthermore, the design of the prosthesis must allow patients to overcome issues with access.6 If there is limited jaw movement due to changes in the TMJ, accuracy of recording a reproducible jaw relationship may be compromised.5
Once the final prosthesis is delivered, the residual ridges and border extension areas are constantly changing, therefore dentures for these patients may require continual adjustments or rebasing.7 Lack of muscular control of the cheeks, lips and tongue may make dentures difficult to control and denture fixative may be needed, depending on how dry the oral mucosa is. Sclerosis of the digits may compromise manual dexterity, complicating the ability of the patient to insert and remove the prosthesis.5,6
The following case describes an alternative technique for the fabrication of sectional maxillary and mandibular complete dentures for a patient with systemic sclerosis and Sjögren’s syndrome.
A 69-year-old female patient was referred to the Charles Clifford Dental Hospital Department of Restorative Dentistry for prosthetic rehabilitation. The referring general dental practitioner (GDP) considered that specialist input was needed due to the effect that the patient's severe microstomia and xerostomia would have on the ability to make successful prostheses.
The patient's medical history revealed systemic sclerosis affecting the upper gastrointestinal tract, lower respiratory tract and musculoskeletal system, secondary Sjögren's syndrome, rheumatoid arthritis, systemic lupus erythematosus, fibromyalgia, osteoporosis, osteoarthritis and spinal spondylosis.
The patient's chief complaint was difficulty eating; she had recently become edentulous and had no complete dentures but had worn partial dentures in the past. Her eating difficulties were worsened by her extremely dry mouth; she was using artificial saliva sprays and gels but did not find them particularly helpful.
Extra-oral examination revealed a restricted oral aperture with maximum opening of 20 mm. The facial skin was taught and had the classic ‘mask-like’ appearance seen in SSc (Figures 1–3). The patient's hand movements were restricted by deformity of the fingers (Figure 4).
Intra-oral examination revealed extremely dry mucosa and retained roots at the UR3, UL3 and UL5 sites (Figure 5). The remaining alveolar ridge in the maxilla was small with shallow sulcus depths but the ridge was fairly broad. The mandibular arch exhibited considerably more resorption than the maxillary arch; the residual ridge was narrow and fairly flat, and there was limited depth to both the buccal and lingual sulci (Figure 6).
Given the severely reduced oral opening, it was decided that sectional upper and lower complete dentures should be fabricated to rehabilitate the patient, and that the retained roots should be kept as overdenture abutments as they were helpful in maintaining the alveolar bone width and height.8
The primary impressions were made in an irreversible hydrocolloid (Alginate Plus, Henry Schein, New York, USA) using the smallest available stock trays further modified to fit the patient's mouth. The primary casts were fabricated in dental stone.
Sectional custom impression trays for both arches were fabricated from light-cured acrylic resin (Kemdent, Swindon, UK). The two halves of the maxillary tray were made with interdigitating components in the palatal region and in the tray handle. Once located together, a 3 mm thick metal locking bolt featuring a 90° handle that passed through the tray handle was used to lock the two halves together (Figure 7). The mandibular tray was fabricated in a similar fashion (Figure 8). Both trays were constructed with tissue stops to ensure stability of the tray in the mouth as well as uniformity of impression material and pressure.
At the master impressions clinical stage, each half of the maxillary and mandibular trays were border moulded using green compound (Kerr, California, USA) (Figure 9). The impressions were made with medium bodied addition silicone (Aquasil Ultra Monophase, Dentsply, Pennsylvania, USA) in two halves as follows. One half of the sectional tray was loaded with impression material, inserted into the mouth and the impression was made (Figure 10). It was then removed and inspected and any excess material that had flown into the interdigitating parts was removed. This half was then re-seated in the mouth whilst the second half of the tray was loaded and inserted into the mouth, ensuring the interdigitating components fully engaged. The two halves of the tray were then locked together with the metal pin inside the mouth until the material had fully set. The pin was removed to allow each half to be removed from the mouth separately. After inspection, the pin was reinserted to lock both halves together again for disinfection and pouring of the master cast (Figure 11).
The master casts were poured using refractory die stone (Figure 12). Sectional temporary record bases were fabricated on these casts using light-cured acrylic resin (Kemdent, Swindon, UK). Wax registration blocks were fabricated on these bases that were located with interlocking components similar to those used in the custom trays. The presence of wax rims made it impractical to incorporate metal locking bolts at this stage (Figure 13).
The standard procedure in complete denture fabrication for adjusting the maxillary and mandibular wax rims for the prescription of the tooth set up and vertical dimension was followed and the jaw relationship was recorded in centric relation using a bite registration addition silicone (VPS-Hydro Bite, Henry Schein, New York, USA).
Transfer of the recorded jaw relationship to an average value articulator, set up of teeth and try-in of the prosthesis were carried out in the conventional manner (Figure 14).
Fabrication of the maxillary prosthesis began with casting of a cobalt chrome (Sheralit Cylindra, Shera Werkstoff Technologie, Lemförde Germany) framework with retention mesh on the right-hand side and plate contacting tissue on the left. The left side of this framework incorporated the implant replicas which were attached via acrylic resin. The implant replicas have a modified connecting system with Locator™ abutments (Zest Dental Solutions, California, USA) attached; this allows them to be replaced in the future if needed (Figure 15). From a silicone putty index of the trial denture, the right-hand section of the denture carrying UR6 to UL2 teeth (Natura Denture Teeth, Shottlander, Letchworth, UK) and the acrylic polished surfaces and flanges were added. A pourable cold-curing methyl methacrylate (Palapress®, Heraeus Kulzer, Hanau, Germany) was used. To process the left section of the denture, thin tin foil relief was placed over the left side of the framework to prevent bonding of the acrylic to the metal. This part of the denture carried UL3 to UL6. The Locator™ Denture Processing Caps (Zest Dental Solutions, California, USA) were added in following this with cold cure acrylic (Figures 15, 16).
The lower prosthesis was fabricated in a similar fashion.
At the delivery stage the dentures were first tried into the mouth to assess fit, occlusion and aesthetics, which were all satisfactory. The patient then had the opportunity to practise insertion and removal whilst in the dental chair. She quickly adapted to the technique of assembling and disassembling the prostheses intra-orally. Note that no coloured Locator™ Males were placed in the processing cap as it would have been too difficult to unlock the two sections in the mouth due to their strength. On account of the dry mouth, the use of a saliva substitute (Biotène OralBalance, GSK, Brentford, UK) and denture fixative (Fixodent®, P&G, Ohio, USA) was used. The patient was also advised to moisten her mouth with water prior to inserting the dentures, and use the artificial saliva substitute throughout the day. Denture care and oral hygiene instructions were given to the patient by an Oral Health Educator and follow up appointments were scheduled one week, two weeks, four weeks and eight weeks post-delivery.
The patient has adjusted well to the dentures with marked improvement in her masticatory efficiency and self-confidence. With the exception of minor pressure areas that required the denture to be relieved, no significant changes have needed to be made thus far (Figure 17).
Patients with microstomia presenting for prosthetic rehabilitation pose a challenge to the clinician and laboratory technician, however, they can be managed conservatively by modification to the conventional clinical and laboratory procedures already in place.
Fully or partially dentate patients with SSc often present with dental caries and/or periodontal disease. Maintenance of good oral hygiene can be physically challenging due to restricted access to the oral cavity and reduced manual dexterity, which can compromise the ability to use toothbrushes and interdental cleaning aids.9,10 Microvascular abnormalities within the gingival tissues have been observed which may subsequently have a negative effect on the periodontium and contribute to the development of periodontal disease.11 Higher levels of vascular endothelial growth factors have been observed in gingival biopsies of patients with SSc compared to healthy controls.12 Prevention and management of dental caries and periodontal disease does not differ from that of the general population. Diet advice to limit sugar intake, prescription of high fluoride toothpastes or mouthwashes, education on oral hygiene techniques and adapted dental appliances will be of value.13
However, as SSc progresses, access to the oral cavity becomes increasingly difficult for the GDP who eventually may be unable to provide treatment for the patient.
As the dentition fails, extraction often becomes the treatment of choice due to the technical challenges in restoring the natural dentition, but subsequent rehabilitation with prostheses is also complicated. There is often reduced support for dentures and constructing a well-fitting, well-adapted prosthesis is challenging due to the difficulties presented by microstomia. Many patients with SSc also have xerostomia, either due to gland fibrosis or the acinar cell destruction of Sjögren's syndrome. Dryness of the oral mucosa further complicates the clinical stages of denture construction and compromises retention due to absence of adhesive and cohesive forces of saliva.14
Several methods have been described for constructing sectional impression trays and dentures in the literature. The use of sectional impressions, which may be recorded in two or more parts, and then relocated outside the mouth, is a useful technique. Custom trays with dovetail locks, pins, press studs, stepped or butt joints have been described. In this particular case, a combination of pins and stepped joints were used to ensure accurate and reproducible relocation of the trays, intra- and extra-orally. The use of flexible plastic stock trays has also been reported in the literature but these need to be reinforced prior to casting to ensure dimensional stability and accuracy of the resultant cast.15,16,17
Other designs for sectional, collapsible or flexible complete dentures have been described in various case reports. A foldable, single piece denture connected by hinges in the midline was described in a case report by Cura et al.18 The bulk of the hinge, however, had the adverse effect of limiting tongue space. Another case report by Arora et al described the use of press studs as used in the textile industry to connect two parts of a sectional denture.19 The technique presented, using implant Locator™ abutments (Zest Dental Solutions, California, USA), is an adapted version of this design. One advantage of using implant Locator™ abutments and processing caps is that all the parts are attached to the base of the denture by acrylic resin and therefore are retrievable should they need to be changed. The strength of the locking mechanism can also be altered, depending on how the sectional prosthesis functions and the ability of the patient to unlock the two parts, by changing the coloured Locator™ Males (Zest Dental Solutions, California, USA) that are seated in the processing cap.
Colvenkar reported the use of button magnets as the locking mechanism for a sectional complete denture.20 The difficulty with using magnets, however, is that the denture must also have some interlocking component built into it to prevent the two halves from sliding over each other during function. The magnets must also be very strong and maintain their strength over time. The effects of using magnets in dental prostheses in patients who are fitted with cardiac pacemakers is not widely known but may pose a risk to these patients.
Where the reduction in mouth opening is less severe, rotational paths of insertion and reduction in occlusal vertical dimension may be enough to facilitate conventional complete dentures.
The use of osseo-integrated dental implants presents a significant opportunity to improve quality of life for these patients. However, these patients are often unsuitable due to insufficient bone volume, and restricted access for surgical procedures, maintenance and self-performed plaque control, as was true in this particular case. Often patients with SSc have other comorbidities, such as osteoporosis, and may be taking antiresorptive drugs. The risk of medication-related osteonecrosis of the jaws (MRONJ) when undergoing surgical procedures is well established, particularly in patients receiving intravenous bisphosphonates, but the evidence for this complication when dealing with dental implants is conflicting and less well recognized. Two systematic reviews, however, conclude that dental implant success rates are not reduced in patients receiving bisphosphonates, although risk evaluation must be carried out on a case-by-case basis to prevent serious complications.21,22
Dental implant outcomes in patients with SSc are not well documented, so the potential effect of any microvascular changes in the jaw bones on osseo-integration is unknown.23 Placement of implants in the anterior region to stabilize a removable prosthesis should be favoured over posterior implants due to increasing difficulties with access as the microstomia worsens over time.24
If identified early, a number of facial exercises and microstomia orthoses can be used to help improve mouth opening. Early intervention is important given the progressive nature of sclerosis. These exercises and devices, such as the TheraBite® (Atos Medical, Malmö, Sweden), are used for prevention or for stretching of the contracted tissue.25 Pizzo et al reported on the efficacy of muscle elongation exercises on improving mouth opening in patients with severe limitation (inter-incisal distance <30 mm). An average increase in mouth opening of 10.7 +/− 2.06 mm was found, with no significant difference between patients with and without teeth.26
Surgical procedures, such as unilateral or bilateral commissurotomy, have also been described as adjuncts to increasing mouth opening. However, given the diminished soft tissue reparative processes associated with SSc, poor wound healing and scarring may occur. Generally, conservative management with daily exercises is preferred.27
The report describes a novel technique for clinical and technical stages in fabricating sectional upper and lower complete dentures, by simple modification of conventional techniques. Through careful planning and design, alongside a good working relationship and close communication with the lab technician, many of the seemingly difficult issues can be overcome. This report and brief review of the literature may help to direct and plan treatment for patients with microstomia, not just related to systemic sclerosis.
