Tooth Sign

Asymptomatic, vaguely dentate ossifications that are perpendicular to the patellar surface seen on an axial—‘skyline’—view of the patello-femoral joint which, while associated with degenerative changes, are of themselves of no clinical significance
DiffDx Paget’s disease of bone, reactive sclerosis due to chronic osteomyelitis
References in periodicals archive ?
There are classic imaging findings in Joubert syndrome, including the molar tooth sign and a bat-wing configuration of the fourth ventricle seen on axial MRI or CT.
Traditionally, all patients with the molar tooth sign on axial imaging were given the diagnosis of Joubert syndrome.
The molar tooth sign is a distinguishing characteristic on axial imaging studies of the posterior fossa in children with Joubert syndrome.
Molar tooth sign in Joubert syndrome: Clinical, radiologic, and pathologic significance.
Molar tooth sign of the midbrain-hindbrain junction: Occurrence in multiple distinct syndromes.
The molar tooth sign was initially identified in Joubert syndrome, named after Marie Joubert who first described it in 1968 as a rare autosomal recessive disorder characterised by the neuroradiological hallmark of the molar tooth sign caused by cerebellar vermian hypoplasia.
The molar tooth sign refers to the characteristic appearance on axial CT or MRI of enlarged and horizontally directed columnar structures on each side of the midline flanking a deep interpeduncular fossa.
Once the molar tooth sign is identified, the brain MRI scan should be reviewed for other associated abnormalities including abnormal configuration and malrotation of the hippocampi, callosal dysgenesis, malformations of cortical development and cephaloceles, which have been described in a sizeable number of patients with JSRDs.
Knowledge of the newer classification system and the subtypes is important as it helps to direct and interpret imaging studies based on clinical signs to avoid delay in diagnosis of the hepatic, oculorenal and renal subtypes of JSRDs in patients in whom the molar tooth sign is identified on brain MRI.
Molar tooth sign in fetal brain magnetic resonance imaging leading to the prenatal diagnosis of Joubert syndrome and related disorders.