Mucopolysaccharidosis type I (Hurler syndrome): oral and radiographic findings and ultrastructural/chemical features of enamel and dentin.

Mucopolysaccharidosis type I (Hurler syndrome, MPS I-H) is an autosomal recessive inborn error of metabolism due to deficient alpha-L-iduronidase enzyme activity and is characterized by accumulation of incompletely degraded glycosaminoglycans that generally lead to impairment of organ and body functions. This report presents oral, dental, and radiographic findings in a boy who presented with MPS I-H. Nine of the patient's primary teeth were extracted and investigated using scanning electron microscopy, x-ray diffraction analysis, and Fourier transform infrared spectroscopy. Compared with the teeth of otherwise healthy patients, MPS I-H-affected dentin was characterized by extremely narrow dentinal tubules, whose direction followed an irregular wave-like pattern. The enamel-dentin junction was defective, as evidenced by microgaps, and the enamel displayed irregular arrangement of prisms. The additional novel observation was made that the protein structure of enamel and dentin changed in MPS I-H-affected teeth. Also, an increase was observed in the relative mineral/matrix ratio of MPS I-H-affected dentin, indicating that its protein content had decreased in comparison with normal dentin.