How does syphilis affect the teeth?

When syphilis is contracted in the womb (congenital syphilis), it can affect the development of teeth. 

With the rise of syphilis cases in the U.S., cases of congenital syphilis are also on the rise. According to the CDC Chief Medical Officer Debra Houry, M.D., M.P.H., “The congenital syphilis crisis in the United States has skyrocketed at a heartbreaking rate,”. In 2022, 3,771 infants tested positive for syphilis, a shocking 10-fold increase since 2012.

Good prenatal care and maternal screening for STIs including syphilis during pregnancy can prevent congenital syphilis and its adverse effects on children. Syphilis is treatable and curable using penicillin.

What is congenital syphilis?

Congenital syphilis is the syphilitic infection that a fetus acquires in the womb from an infected mother. Syphilis is a sexually transmitted bacterial infection that cannot be cleared out by the body’s immune system but needs antibiotics for cure, usually penicillin. If a pregnant woman has untreated syphilis during her pregnancy, the infection can pass on to the baby and cause congenital syphilis.

Congenital syphilis causes birth defects in the fetus. Some manifestations of congenital syphilis may be immediately apparent, while others show up after the child is about five years of age.

Symptoms of congenital syphilis

Early manifestations of congenital syphilis include rhinitis (“snuffles”), skin rash with peeling skin, hepatosplenomegaly (enlarged liver and spleen), eye problems (such as glaucoma, cataracts, inflammation of choroid or retina, and fluid leaking under the retina), long bone defects, anemia, and low platelet count. Some infants may have syphilis but not show symptoms.

If infants remain untreated for syphilis, as children they develop symptoms of late congenital syphilis. These include saddle nose formation, bone and joint problems, eye problems such as interstitial keratitis (inflammation of the corneal stroma) and optic atrophy (damage to the optic nerve that carries signals from the eye to the brain), neurologic deafness, developmental delays, and abnormal teeth development.

Abnormal teeth are a part of a triad of symptoms of congenital syphilis called Hutchinson’s triad which also includes interstitial keratitis and 8th nerve deafness.

How congenital syphilis affects teeth

Dental defects due to syphilis can begin within a few weeks of birth, but they are only seen when the first molars come out or the first permanent incisors come out. This usually happens after the child is over 5 years of age, usually around ages 6-7. The defects are not seen in children’s first teeth (primary teeth, also called milk teeth).

Treponema pallidum, the pathogen that causes syphilis invades the cells that will make the future teeth and inhibits ameloblasts, cells that make tooth enamel.

There are three main defects in teeth caused by congenital syphilis.

• Hutchinson’s incisors. The incisors are short, narrow, and have a “screwdriver shape” or a peg shape. The teeth have a crescent-shaped notch in the middle, which becomes more apparent when the full secondary tooth emerges. The teeth are more translucent than the typical ivory color of healthy teeth. This dental issue was first described in 1861 by Sir Jonathan Hutchinson, Assistant Surgeon at The London Hospital, England.
• Moon’s molars or bud molars. The permanent first molars are small and dome-shaped. The crowns are wider at the base and narrowest at the cusps, and the surface of the cusp is smooth, unlike the cusps of normal molars. This defect was first described by Dr. Henry Moon, a Dental Surgeon at Guy’s Hospital in 1877.
• Fournier’s molars or mulberry molars. This is another defect in the molars caused by congenital syphilis. First described by Dr. Alfred Fournier in 1884, these molars appear as if smaller teeth are growing out of them. Also called mulberry molars, these teeth look very different from Moon’s molars, possibly because of variation in the time at which the dental area got infected by the syphilis pathogen.

Other dental defects that occur due to congenital syphilis include premature loss of primary teeth and palatal perforation (perforation in the bone between oral and nasal cavities).

Treatment of teeth affected by congenital syphilis

Dental procedures such as crowns, fillings, and implants can help repair the teeth that were deformed by congenital syphilis. However, treating and curing the underlying syphilis infection is critical to remove the infection and stop further damage to the child’s health. Syphilis is readily curable by antibiotics. The CDC’s recommended antibiotics regimen is different for infants and children based on their age. Both treatments use a course of penicillin that lasts at least 10 days with repeated testing over time to ensure that the infection is gone.