Medical Emergencies · patient case with 2 questions
Blood pressure rise after local anaesthetic
Patient: Male, 41 years old
Chief Complaint: “The outside of my back tooth broke.”
Background: No systemic disease, no medications, no allergies. Reports being anxious about injections.
Vital Signs: On seating BP 105/65 mmHg · HR 72 bpm. Five minutes after infiltration with 2% lidocaine with 1:100,000 epinephrine: BP 138/86 mmHg · HR 96 bpm. Patient is alert, comfortable, no chest pain, no shortness of breath, no palpitations reported.
Findings: Fractured buccal cusp of tooth #4 with the fracture line above the gingival margin. No pulp exposure. Tooth vital.
Question 1
What is the appropriate next step?
Show answer and explanation
Correct answer: A. Continue with the planned treatment, monitoring the blood pressure
- A. CORRECT. A rise from 105/65 to 138/86 in a healthy, anxious patient after an injection is a NORMAL physiological response — endogenous catecholamine release from anxiety, with a small contribution from the injected epinephrine. The reading remains within normal limits, the patient is asymptomatic, and the anaesthesia itself REDUCES stress once it takes effect. Proceed and monitor.
- B. Prescribing an antihypertensive to treat a transient, normal-range reading is dangerous and outside the dentist's scope. A dose of an ACE inhibitor in a normotensive patient risks symptomatic hypotension.
- C. EMS activation is for genuine emergencies — chest pain, neurological signs, airway compromise, or a hypertensive crisis at or above 180/120 with symptoms. None applies.
- D. Cancelling teaches the anxious patient that anxiety ends appointments, and abandons a treatable tooth for a reading that is not abnormal.
Note: The thresholds that matter: proceed with routine care below 160/100 and refer for evaluation; use caution and limit elective care between 160/100 and 179/109; DEFER elective treatment at 180/110 and above and arrange urgent assessment. A single elevated reading is repeated after five minutes of rest before any decision is made on it.
Question 2
How many roots and pulp horns does tooth #4 typically have?
Show answer and explanation
Correct answer: C. One root and two pulp horns
- A. One pulp horn would imply a single cusp. Premolars are bicuspid by definition, and each cusp is underlain by a pulp horn.
- B. Two roots with one pulp horn is not a configuration seen in any premolar.
- C. CORRECT. Tooth #4 is the maxillary right SECOND premolar. It typically has a SINGLE root with a single canal — in contrast to the maxillary FIRST premolar, which usually has two roots and two canals — and TWO pulp horns, buccal and palatal, corresponding to its two cusps. The buccal horn is the more prominent, which is exactly what matters when a buccal cusp fractures.
- D. Two roots and two pulp horns describes the maxillary FIRST premolar (#5 and #12), the premolar most commonly bifurcated. Second premolars are usually single-rooted.
Note: Carry the pulp-horn count into every deep preparation: it tells you where the pulp is closest to the surface. Maxillary first premolar — two roots, two canals, two horns. Maxillary second premolar — one root, usually one canal, two horns. Mandibular first premolar — one root, one canal, a large buccal horn and a very small lingual one. Mandibular second premolar — one root, one canal, two or three horns depending on the cusp form.