Gardner syndrome has head and neck manifestations that may be recognized during dental visits. Features such as multiple gnathic osteomas, impacted supernumerary teeth, and multiple foci of idiopathic osteosclerosis can be easily identified on dental radiographs, prompting the clinician to refer the patient for further investigation. A dental examination and routine radiographs play a vital role in revealing the extracolonic presentation of Gardner syndrome, which facilitates timely screening and detection of colorectal cancer and other malignancies associated with this condition. This report discusses the case of a 50-year-old Caucasian man who presented with a hard swelling of the left angle of the mandible and was diagnosed with Gardner syndrome based on abnormal findings from an oral examination, dental imaging, and medical and family history.