Dental crown morphology variations associated with congenital syphilis and their importance in paleopathological diagnosis

Abstract

Background Standardized methods to diagnose syphilis in skeletal remains have been established, however, they are not efficient due to the lack of a full set of skeletal manifestations in many individuals, and changes similar to syphilis, occurring in other infections. Similar issues arise for congenital syphilis. Dental and skeletal manifestations do not occur in all cases, and dental signs also vary. It is well documented that mercury was used to treat congenital syphilis before 1943, however, the effects of mercuric treatments on dental formation have not been considered as diagnostic signs. Thus, individuals who do not demonstrate typical dental stigmata have been dismissed as possible cases of congenital syphilis. This thesis investigates dental malformations in cases of congenital syphilis to determine the range of possible dental signs of congenital syphilis, and mercuric treatments. Determining the effects of mercuric treatments on tooth crown development would establish a method for a diagnosis of congenital syphilis based on a full range of abnormalities. Methods The criteria to determine dental signs of congenital syphilis were based on the standard developed by modern scholars and on own study of 19th century descriptions and illustrations of patients. To determine dental signs of mercuric treatments, descriptions and illustrations of teeth of congenital syphilis patients treated with mercury by 19th century physicians were used. These are the first and only observations made of dental signs attributed to congenital syphilitic treatments. Dental criteria were applied in a survey of remains of 259 individuals from several skeletal collections: the Wellcome Museum of Anatomy and Pathology, London, St Mary’s cemetery, South Australia, Smithsonian Institute, Washington DC, and the Cleveland Museum of Natural History, Cleveland, Ohio. Dental traits attributed to congenital syphilis (Hutchinson’s incisor, Moon’s, and Fournier’s molars, and canines with sharp groove-like hypoplastic defects on the tip) and its treatments were recorded. In cases where it was permitted, levels of mercury were tested for using portable x-ray fluorescence (pXRF). Furthermore, paleopathological cases from the literature with high quality dental images were used. A history of the use of mercury to treat congenital syphilis and syphilis in the United States and Europe was explored based on government reports and the literature. Results Congenital syphilis and mercury affect similar kinds of permanent teeth, (incisors, first molars, and canines) due to tooth development times. However, mercury and congenital syphilis affect odontogenesis and amelogenesis differently resulting in distinct malformations exhibiting individual variation. The range of variation has been established and illustrated. Levels of mercury detected in hard tissues do not prove nor disprove the use of mercury as a form of treatment of congenital syphilis due to mercury turnover in the body. Conclusion Variation beyond the classical models of congenital syphilitic teeth occurs. Dental signs produced by mercury should be considered when making a differential diagnosis of congenital syphilis. This is the first study to consider the use of dental signs associated with congenital syphilitic treatments in a paleopathological context which could help elucidate controversial cases of the disease and shed some light on its origins.