Periodontics · patient case question
Which best describes the microbiology of established periodontitis?
Patient case: Deep pockets and a rising HbA1c
demo: 49-year-old female
chief: Bleeding gums and bad taste; she has noticed her front teeth are drifting.
history: Type 2 diabetes for eight years, most recent HbA1c 8.9 percent. Smokes half a pack a day. An implant placed at site 30 two years ago has recently begun to feel tender.
meds: Metformin, estradiol.
findings: Generalised probing depths of 5 to 6 mm with bleeding on probing at 62 percent of sites and no acute symptoms. Radiographs show generalised horizontal bone loss and saucer-shaped bone loss around the implant at 30 with bleeding and suppuration on probing.
Show answer and explanation
Correct answer: C. Predominantly anaerobic gram-negative rods
- A. Facultative gram-positive rods such as Actinomyces belong to early colonisation, before the anaerobic shift occurs.
- B. Aerobic gram-positive cocci such as streptococci dominate healthy supragingival plaque, which is the opposite end of the ecological shift.
- C. Correct. The deepened pocket is an anaerobic, protein-rich niche that selects for gram-negative rods. The red complex of Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola, along with Prevotella and Fusobacterium, are all gram-negative and largely rod or spirochaete in form.
- D. Veillonella is an anaerobic gram-negative coccus present in plaque, but cocci are not the dominant morphotype of the periodontitis flora.