Introduction

Parry-Romberg Syndrome (PRS) is a rare condition that causes gradual shrinking (atrophy) of soft tissues, fat, muscle and often bone on one side of the face.¹ This condition was named after the scientist Parry, who described it in 1825, and Romberg in 1846.² It usually starts in childhood or early teenage years. It is estimated to affect 1 in 700,000 people.⁸

This condition progresses over timeand stops at an age.⁷ There is no defined treatment for this disease. After the progression stops, reconstruction surgery can be considered. This condition affects not only how the face looks but also how the mouth works, how teeth erupt and how comfortable chewing and speaking are.¹ We will explain these oral and dental changes in simple terms. 

Pathophysiology in brief

Doctors do not yet know why PRS happens. Several theories exist, including autoimmunity, nerves, trauma or problems with blood supply. This condition looks most similar to linear scleroderma en coup de sabre (LSCS).⁷ The key difference is that PRS usually does not cause hardening of the skin or scarring hair loss. In LSCS, the scalp often becomes thick and firm, with dark patches and loss of scalp hair or eyebrows.⁷

PRS usually progresses slowly over a few years, then tends to stabilise. Because tissue is lost on one side of the face, that side’s bones, muscles and skin shrink or fail to grow as much as the other side. This creates asymmetry (uneven face appearance). 

Oral and dental manifestations

Here are the things that people with PRS often have in the mouth, teeth, jaw and related areas. Not everyone has all of these. Severity depends on age, how fast the disease progresses, and how early treatment happens.

Soft tissues

• The tongue on the affected side may shrink (atrophy).⁶ This can make it look uneven.
• Some of the muscles used for chewing (the masseter and thepterygoid muscles) may waste or weaken on that side⁶
• The lips, the soft palate or the angle of the mouth may be altered; the lips may be pulled or shifted and soft tissues become thinner⁷

Tooth eruption and development

• Teeth on the affected side may erupt from the gums later than normal¹ 
• Sometimes teeth may be missing
• Tooth roots may be underdeveloped or show root atrophy or resorption⁶

Jaw and bone structure

• One jaw (upper or lower) may be smaller on the affected side. This can make the face look uneven
• The vertical height of part of the lower jaw (the ramus) may be reduced²
• Bone loss or thinning of the jaw or facial bones (the mandible, the maxilla and the zygomatic arch) can happen⁶

Bite, occlusion and alignment

• Because jaws and teeth are uneven, an open bite or crossbite often appears (teeth don’t meet properly when biting)⁶
• The mouth may deviate. Thejaw may shift when opening or closing⁶

Functional issues

• Chewing may be more difficult on the affected side
• Speech may be affected if tongue or palate involvement is significant
• Maintaining oral hygiene (clean teeth and gums) can be difficult due to asymmetry, delayed tooth eruption or root problems. This can lead to more decay or gum issues

Diagnostic considerations

A dentist or doctor will check for facial asymmetry (one side looking smaller) and other visible signs. such as changes in the lips, the tongue or the cheeks. X-rays or other imaging, like panoramic radiographs, CT or MRI, help to see how bones, the jaws, and the roots of teeth are affected.¹ Sometimes, PRS is confused with other conditions (like scleroderma or localised skin disorders). Correct diagnosis allows for proper treatment. 

Management strategies

Treatment for the oral and dental manifestations needs specialists from various fields. These include dentists, orthodontists, surgeons, dermatologists and rheumatologists. The orthodontist can do the teeth alignment that can help with an uneven bite. The facial deformities can be corrected with reconstructive surgery or cosmetic treatment to improve the facial features.⁷ This can be done only when the disease progression is stabilised. Regular dental checkups are important. This may involve teeth cleaning, dental filling and monitoring teeth development.

Case study example

A 10-year-old boy had PRS on the left side.¹ On examining his mouth:

• The tongue was uneven because the left side was thinner (atrophied)
• Some teeth (first and second premolars) on the left did not erupt fully
• The roots of these teeth were shorter and the pulp chambers (the insides of the teeth) looked narrower
• The ramus of the lower jaw was slightly shorter on the affected side
• There was an open bite on the left side (the teeth do not touch when biting)

This case shows many common oral and dental changes in PRS.

Another report described a 15-year-old boy who developed PRS after a sports injury.²
Two years after a kabaddi accident, his family noticed a slow shrinking of the right side of his face.
He had no major medical problems and normal speech and hearing.

Clinical features:

• Visible facial asymmetry with a scar-like mark near the right cheekbone
• Atrophy of facial muscles and smaller frontal and maxillary sinuses on scans
• Normal teeth and bite, though the right side of the jaw looked smaller

Blood tests were normal except for low vitamin D. He was given methotrexate and prednisolone for two months, with vitamin D and topical cream. After follow-up, disease progression stopped. Reconstructive surgery with fat grafts was planned once his growth stopped.

The role of dentists in early detection

Dentists play a key role in noticing PRS early. Here’s what can help:

• During regular dental checkups, dentists should look for facial symmetry and deformations
• Dental examination should include teeth eruption in chronological order
• Tongue examinations should be done to check if there is asymmetry
• The buccal side of soft tissues must be examined to check if there is any thinning on one side
• Radiological findings must be carefully evaluated to rule out bone, jaw and tooth deformities
• Regular dental checkups should include extraoral examinations that must include facial deformities
• Refer to specialists early if these signs are seen: early management leads to better outcomes

Why these changes matter

• Oral changes affect chewing, speaking and swallowing; they reduce comfort and function
• Delayed or uneven tooth growth can lead to a painful or difficult bite
• Appearance changes (including facial asymmetry or uneven teeth or tongue) can affect self-esteem and mental health, especially in children or teens
• Poor oral hygiene or delayed care can lead to decay or gum disease

What patients can do

• Follow regular dental appointments, at least once every 6 months
• Inform your dentist if you find any facial changes, teeth malalignment, delayed tooth eruption or if your tongue feels less full
• Proper oral hygiene should be maintained by brushing twice daily and regularly flossing
• If you find any abnormality, ask your dentist for an X-ray so that they can diagnose any internal deformities
• Refer to specialists for opinions regarding teeth misalignment and changes if you feel any difficulty in eating, speaking or changing financial appearance

Summary

Parry-Romberg Syndrome is rare, but its effects go beyond skin and facial appearance. The mouth, teeth, jaw and tongue can all be affected. Oral and dental changes can give early clues. The exact cause is unknown, but autoimmune and nerve factors are suspected. Regular dental check-ups, imaging and team care are vital for diagnosis and management. Treatment focuses on slowing the disease and restoring appearance once the condition stabilises. 

Detecting changes early helps reduce problems with function and appearance. A team-based approach, including dental care, orthodontics and possibly surgery, tends to give the best results. If you or a family member notices facial or dental asymmetry, asking a dentist to check further could make a big difference.