What syndrome is characterized by supernumerary teeth and the presence of clavicles?

The presence of supernumerary teeth, which are additional teeth beyond the normal complement, and the presence of clavicles are hallmarks of Gardner's syndrome. This genetic disorder is a type of familial adenomatous polyposis and is associated with multiple extra teeth, along with various other dental anomalies, as well as osteomas (benign bone growths) and soft-tissue tumors.

Gardner's syndrome often presents with symptoms that include problems related to the teeth and dental structure alongside these unique skeletal characteristics, such as irregularities in the clavicles. While the other syndromes mentioned may have their own distinct set of features—ranging from connective tissue issues in Marfan syndrome to developmental and chromosomal characteristics in Down and Turner syndromes—none of them specifically involve the combination of supernumerary teeth and clavicular presence as a defining feature. Hence, Gardner's syndrome is the correct association in this context.