Dentistry
What this domain tests
Dentistry tests oral anatomy, periodontal disease, dental charting and radiography, professional prophylaxis, extraction technique, and the anesthesia and analgesia that make dental work safe. Triadan numbering, staging, and local blocks are high-yield.
Anatomy and charting
- Dogs have 42 permanent teeth; cats have 30.
- Dog formula: 2 × (I 3/3, C 1/1, P 4/4, M 2/3). Cat formula: 2 × (I 3/3, C 1/1, P 3/2, M 1/1).
- Triadan system: 100s upper right, 200s upper left, 300s lower left, 400s lower right. Canine teeth are 104, 204, 304, and 404.
- Record probing depth, mobility, furcation involvement, gingival recession, fractures, and missing teeth.
- Periodontal disease is staged 0–4 by attachment loss; stage 3 indicates moderate and stage 4 advanced disease.
Prophylaxis and extraction
- Dental work requires general anesthesia with an endotracheal tube and a throat pack.
- Take intraoral radiographs before extraction to identify roots and bone loss.
- Scale supragingivally and subgingivally with ultrasonic and hand instruments, then polish with pumice and irrigate. Polishing smooths the enamel after scaling.
- Use closed extraction for mobile single-rooted teeth; use a flap and section multi-rooted teeth for open extraction.
- Regional blocks-maxillary, infraorbital, mandibular, and mental-improve analgesia and lower anesthetic requirements.
Worked example
A 5 kg cat needs a mandibular block. Using a conservative feline lidocaine ceiling of 2 mg/kg: 5 × 2 = 10 mg. A 2% solution is 20 mg/mL, so 10 ÷ 20 = 0.5 mL maximum. Draw up no more than 0.5 mL, aspirate before injecting, and inject slowly. Reasoning: cats are more sensitive to lidocaine toxicity, and calculating the volume against the concentration prevents an accidental overdose.
Traps that cost marks
- Scaling without polishing leaves a rough surface that collects plaque faster.
- Extracting without radiographs, risking retained roots and a draining tract.
- Holding an ultrasonic scaler tip at the wrong angle and damaging enamel.
- Exceeding local anesthetic ceilings, especially in cats.
- Leaving the throat pack in place or failing to chart pre-existing disease.