Progressive Systemic Sclerosis

Progressive systemic sclerosis (SSc) is a chronic, systemic autoimmune connective tissue disease characterized by a pathogenic triad of microvasculopathy, immune dysregulation, and progressive fibrosis of the skin and internal organs.[1][2] The etiology remains unknown, though the disease process involves endothelial dysfunction, autoantibody production (anticentromere, anti-topoisomerase I, anti-RNA polymerase III), and excessive extracellular matrix deposition by dysregulated myofibroblasts.[1][3] In the jaws, SSc produces a characteristic constellation of radiographic findings dominated by uniform widening of the periodontal ligament (PDL) space and resorptive changes of the mandible, particularly at muscle attachment sites.[4][5] Management is multidisciplinary, centered on systemic disease-modifying therapy coordinated with preventive oral care and rehabilitation of limited mouth opening.[6]

• Systemic sclerosis (SSc) is the current preferred term in the 2013 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria.[7]
• Scleroderma remains widely used in clinical practice and is acceptable as a synonym; however, it can cause confusion with localized scleroderma (morphea), which is a distinct entity without systemic involvement.[2][8]
• Progressive systemic sclerosis is an older designation that emphasizes the progressive nature of the disease; it is still encountered in oral radiology literature but has been largely supplanted by "systemic sclerosis".[2]
• Two principal subtypes are recognized based on extent of skin fibrosis: limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc). The acronym CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) describes a clinical pattern most often associated with lcSSc.[7]
• SSc sine scleroderma is a rare subtype with visceral and vascular involvement but no clinically detectable skin fibrosis.[7]

• Sex and age: SSc predominantly affects women (female-to-male ratio approximately 4–6:1), with peak onset between ages 30 and 50.[7][9]
• Incidence and prevalence: Annual incidence is approximately 1–4 per 100,000 person-years, with global prevalence ranging from approximately 1 to 38 per 100,000, showing marked geographic heterogeneity.[7][9]
• Racial disparities: Incidence is approximately 2.5 times higher in Black patients, who also experience more severe pulmonary involvement and worse prognosis.[7][9]
• Oral involvement: Orofacial manifestations occur in more than two-thirds of SSc patients. PDL widening has been reported in 38–80% of patients depending on the study and imaging method used. Mandibular resorption is reported in approximately 7–47% of patients across series.[4][5][10][11]

Orofacial soft tissue findings

• Microstomia is one of the most functionally debilitating oral manifestations, resulting from progressive fibrosis of the perioral skin, facial muscles, lips, and cheeks.
• The perioral skin develops characteristic radial furrowing, and the lips become constricted ("fish mouth" appearance).[13]
• Xerostomia is common, resulting from fibrotic changes in salivary glands and, in approximately 20–33% of patients, secondary Sjögren syndrome. Reduced salivary flow increases susceptibility to dental caries and candidiasis.[14][15]
• The tongue may become stiff and narrowed ("chicken tongue" or scleroglossus), and the sublingual frenulum thickens.[13][15]
• Firm whitish or yellowish fibrotic mucosal plaques and bands may be seen in the buccal mucosa and vestibular sulci.[13]
• Facial telangiectasias are common, particularly in lcSSc.[14]

Periodontal and dental findings

• Periodontal disease is frequent, with attachment loss, reduced bleeding on probing, and accelerated tissue breakdown attributed to vascular insufficiency and impaired oral hygiene.[12][14]
• Increased caries prevalence and higher numbers of missing teeth are observed.[16]

Temporomandibular joint symptoms

• TMJ dysfunction (pain, joint sounds, restricted mandibular movements) is reported in 20–93% of SSc patients and correlates with disease activity and extent of skin fibrosis.[17][18]

Systemic context

• Oropharyngeal dysphagia occurs in up to 25% of patients. Visceral fibrosis—particularly interstitial lung disease and pulmonary arterial hypertension—drives the majority of SSc-related mortality.[1][7][15]
• An increased risk of tongue carcinoma has been reported in the diffuse cutaneous subset.[6][15]

Location and distribution

• Radiographic changes in SSc affect the mandible almost exclusively among the jaws. The maxilla is generally spared.[5]
• PDL widening tends to involve posterior teeth preferentially, though it may be generalized. It can affect any tooth and is often bilateral and symmetric.[4][11][16]
• Mandibular resorptive changes follow a characteristic distribution corresponding to sites of masticatory muscle attachment: the gonial angles (most common), condylar heads, coronoid processes, and posterior border of the ramus.[5]

Periodontal ligament space

• Uniform widening of the PDL space is the most common and characteristic dental radiographic finding of SSc. It is typically generalized, involving multiple teeth, and appears as a symmetric broadening of the radiolucent PDL space around the roots.[4][10][16]
• The widened PDL is believed to reflect excessive collagen deposition within the periodontal ligament rather than inflammatory periodontal disease. Importantly, the lamina dura usually remains intact, and angular bone defects and tooth mobility are typically absent—distinguishing this finding from periodontitis or occlusal trauma.[5][10][16]
• PDL widening may be one of the earliest radiographic signs of SSc and has been correlated with disease severity, skin score, and anti-topoisomerase I antibody positivity.[5][10][11]
• Unawareness of this SSc-specific finding can lead to misdiagnosis as endodontic or periodontal pathology and unwarranted tooth extraction.[5]

Lamina dura changes

• Thickening of the lamina dura is a common finding, reported in approximately 45% of patients in one panoramic study. This is an unusual radiographic pattern, as most systemic conditions that widen the PDL space (e.g., hyperparathyroidism) tend to cause loss rather than thickening of the lamina dura.[4]

Mandibular cortical bone

• Radiomorphometric analysis on panoramic radiographs demonstrates significantly reduced mandibular cortical indices (mental index, panoramic mandibular index, mandibular cortical index) in SSc patients compared with controls, indicating cortical thinning and increased porosity of the inferior mandibular cortex.[4]

Mandibular resorption

• Osteolytic resorption of the mandible occurs at characteristic sites that coincide with muscle attachment zones:[5]
  • Gonial angle (masseter insertion): most frequently affected
  • Condylar head (lateral pterygoid insertion): second most common; bilateral condylysis is occasionally observed
  • Coronoid process (temporalis insertion)
  • Posterior ramus border
• Resorption is attributed to a multifactorial process combining microvasculopathy, pressure ischemia from fibrotic and atrophic muscles, and skin hardening. Resorption may occur at any point during the disease course and does not consistently correlate with disease severity.[5]
• Severe resorption can rarely predispose to pathological fracture, osteomyelitis, or trigeminal neuropathy from compression of the inferior alveolar nerve.[5][15]
• Zygomatic arch resorption has been reported occasionally.[19]

Effects on teeth and adjacent structures

• Teeth themselves are not directly affected by SSc; root resorption is not a feature.
• Increased caries and tooth loss are secondary consequences of xerostomia and impaired oral hygiene rather than direct bony or dental pathology.[12][14]

Soft tissue calcifications

• Dystrophic calcinosis (calcium hydroxyapatite deposition) is a recognized systemic feature of SSc, occurring in approximately 25% of patients overall. In the orofacial region, soft tissue calcifications may occasionally be visible on panoramic or cross-sectional imaging, though they are far more common in the hands and periarticular tissues of the extremities.[20][21][22]

Volumetric imaging observations

• Cross-sectional imaging confirms and better delineates the extent of PDL widening, particularly in posterior teeth, and allows three-dimensional assessment of condylar and ramus erosions. It is also superior for detecting early or subtle cortical erosions at muscle attachment sites and for evaluating TMJ osseous changes including condylar flattening, erosion, and diminished joint space.[11][17]

MRI of the temporomandibular joint

• MRI demonstrates a higher prevalence of disk displacement, articular surface irregularities, and osseous changes (condylar erosion, flattening) in SSc patients compared with healthy controls. These findings correlate with clinical TMJ dysfunction and may guide decisions regarding conservative versus surgical management of condylar disease.[5][17]

Ultrasound for calcinosis

• Ultrasound offers high sensitivity (approximately 89%) for detecting calcinosis and acroosteolysis in the hands and can characterize surrounding soft tissue inflammation. While primarily applied to the extremities, ultrasound may occasionally be useful for evaluating perioral or cervicofacial soft tissue calcifications.[23]

Medical CT for calcinosis quantification

• Conventional CT and dual-energy CT provide superior anatomic detail and quantification of calcinotic deposits compared with plain radiography, and may be used for disease burden assessment and monitoring.[21][22]

The combination of uniform PDL widening with intact lamina dura, mandibular resorption at muscle attachment sites, and cortical thinning in a patient with known or suspected connective tissue disease is highly suggestive of SSc. However, individual radiographic features—particularly PDL widening or mandibular osteolysis—overlap with several other conditions.

The highest-risk diagnostic pitfall is misinterpreting the generalized PDL widening of SSc as inflammatory periodontal or endodontic disease, which can lead to unnecessary extractions in a patient population already at risk for accelerated tooth loss.[5] When PDL widening is an incidental finding in a patient without a known SSc diagnosis, referral for rheumatologic evaluation (including autoantibody screening and capillaroscopy) is appropriate.[7][8]

Skin and soft tissue

• The histopathological hallmark of SSc is excessive deposition of dense, hyalinized collagen in the dermis, with replacement of subcutaneous adipose tissue. Early lesions show perivascular mononuclear inflammatory infiltrates and edema; established lesions demonstrate compact, homogeneous collagen bundles with reduced cellularity.[26][27][28][29]
• Myofibroblasts (α-SMA–positive) are prominent in active fibrotic skin and correlate with clinical skin scores. Endothelial-to-mesenchymal transition has been identified as a contributor to the fibrotic process.[26][28][30]
• Small vessel changes include intimal proliferation, luminal narrowing, and capillary loss.[1][28]

Oral and periodontal tissues

• Gingival biopsies in SSc patients show more intense inflammatory infiltrates compared with controls, with altered vascular endothelial growth factor expression reflecting the characteristic defective vascularization.[5]
• Elevated levels of IL-6, MMP-9, and CXCL-4 have been measured in gingival crevicular fluid of SSc patients, indicating active local inflammation and tissue remodeling at the periodontal interface.[16]
• The PDL widening is attributed to increased collagen deposition within the ligament space rather than to inflammatory destruction, which explains the preservation of the lamina dura.[10][16]

Radiologic-pathologic correlation

• The generalized PDL widening reflects the same fibrotic overproduction of collagen that characterizes skin and visceral involvement. Mandibular resorption corresponds histologically to ischemic osteolysis at sites of vascular compromise and mechanical stress from fibrotic muscles. Calcinotic deposits consist of calcium hydroxyapatite within dystrophic soft tissues.[5][10][22]

Systemic disease management

• SSc management is directed by rheumatology and is individualized based on disease subtype and organ involvement. Disease-modifying therapies target fibrosis (e.g., mycophenolate, nintedanib for interstitial lung disease), vasculopathy (e.g., calcium channel blockers, endothelin receptor antagonists for pulmonary arterial hypertension), and immune dysregulation.[1][7]
• Pulmonary involvement (ILD and PAH) accounts for more than 50% of SSc-related deaths.[7]

Oral and dental management

• Preventive care is the cornerstone of oral management:[5][6]
  • Patient education on adapted oral hygiene techniques (electric toothbrushes, ergonomic handles for patients with impaired manual dexterity)
  • Regular periodontal maintenance, topical fluoride applications, and management of xerostomia (saliva substitutes, sialogogues)
  • Treatment of gastroesophageal reflux to maintain oral pH
  • Tobacco cessation is strongly recommended given worsened mucosal involvement and increased malignant transformation risk[5][6]
• Systematic panoramic radiography is recommended for early detection of caries, PDL changes, and mandibular resorption.[6]

Microstomia rehabilitation

• Flexible sectional dentures and splint therapy may be indicated for prosthetic rehabilitation.[6]

Dental implants

• Dental implants are a consideration for tooth replacement but require careful patient selection accounting for disease severity, bone quality, xerostomia, bisphosphonate use, and healing capacity.[6][12]

Mandibular resorption

• Mandibular resorption is usually asymptomatic and discovered incidentally on routine radiographs; regular radiographic follow-up is warranted given the risk of pathological fracture.[5]
• Management of condylar resorption ranges from conservative approaches (functional appliances) to surgical intervention (osteotomy, condylar resection, costochondral graft reconstruction) depending on severity and functional impairment.[5]

Prognosis

• Oral manifestations are chronic and progressive, paralleling systemic disease course. Early multidisciplinary intervention improves oral health outcomes and quality of life. Overall SSc prognosis depends primarily on the extent of visceral involvement; 10-year survival varies substantially by subtype and organ complications.[1][5][9][12]

Autoantibody-specific oral correlations

• Anti-topoisomerase I (Scl-70) antibody positivity and diffuse cutaneous disease subset are associated with a greater number of teeth exhibiting PDL widening and with more severe mandibular erosions. Autoantibody profiling may therefore help predict the likelihood and severity of oral radiographic manifestations.[10][11]

Overlap syndromes

• Up to 20% of SSc patients have features overlapping with other connective tissue diseases (lupus, myositis, Sjögren syndrome). Secondary Sjögren syndrome in particular compounds xerostomia and caries risk, requiring intensified preventive dental care.[8][14][15]

Tongue carcinoma risk

• An increased incidence of tongue squamous cell carcinoma has been reported in patients with diffuse cutaneous SSc. Clinicians should maintain a low threshold for biopsy of suspicious oral mucosal lesions in this population.[6][15]