Oral Pathology and Oral Microbiology
Oral Pathology and Oral Microbiology tests the diagnosis of cysts, odontogenic tumors, mucosal lesions, and salivary disease, plus the microbial ecology of caries and periodontal disease.
Core rules
- Dentigerous cyst encloses the crown of an impacted tooth and attaches at the cementoenamel junction.
- Odontogenic keratocyst has a parakeratinized lining, palisaded basal cells, and a high recurrence rate.
- Ameloblastoma is locally aggressive, often multilocular in the posterior mandible, and shows reverse polarity and stellate reticulum-like areas.
- Leukoplakia is a clinical term, not a histologic diagnosis; biopsy is required.
- Streptococcus mutans is associated with caries initiation; Lactobacillus with progression.
Worked example
A 22-year-old has a well-defined unilocular radiolucency around the crown of an impacted mandibular third molar. The diagnosis is a dentigerous cyst. The key reasoning is the attachment at the CEJ and enclosure of an unerupted crown. An odontogenic keratocyst may also occur in the posterior mandible but often grows along the bone with less expansion and does not characteristically surround a crown in this way.
Traps
- Do not call every white patch leukoplakia; candidiasis and lichen planus can mimic it.
- Ameloblastoma and OKC both recur, but OKC is more likely multiple in nevoid basal cell carcinoma syndrome.
- Radicular cyst is inflammatory and associated with a nonvital tooth.
- Candida albicans is normal flora but becomes pathogenic with denture stomatitis or xerostomia.