Pharmacologic behavior (AAPD QE Prep Dr. Nelson) Exam Questions With Verified Answers

Pharmacologic behavior (AAPD QE Prep Dr. Nelson) Exam Questions With Verified Answers What was the chronology of anesthetic discovery (starting with cocaine till now)? - answer1) Cocaine (1885) 2) Procaine (1904) 3) Lidocaine (1943) 4) Articaine (2000) What Cranial nerve do we block most frequently in dentistry? what are its branches and functions? - answer1) Cranial Nerve (V); Trigeminal Nerve 2) 3 Branches: a) V1: Opthalmic branch b) V2: Maxillary branch (Superior alveolar, etc) c) V3: Mandibular branch (IAN, Lingual, etc) 3) Functions: Sensory and Muscular innervation a) Sensory: Face, sinus, Teeth, etc b) Motor: Muscles of mastication 1) masseter, temporalis, Medial/lateral pterygoid How Does local anesthetic work? How many nodes of ranvier be involved for an effective block? - answer1) LA reversibly blocks sodium channels 2) at LEAST 3 nodes of ranvier need to be blocked for inhibition of nerve depolarization What inherent property of LA is required for it to pass the nerve membrane? - answer1) Non- Polarized 2) Fat soluble Rank these sensations by the amount of block experienced by LA...... warm, cold, touch, pain, pressure. - answer1) Pain 2) Cold 3) Warmth 4) Touch 5) Deep pressure Name the three parts of a Local anesthetic (structure/composition-wise) and there roles. - answer1) Lipophilic (to penetrate anatomic barrier) 2) Intermediate chain (amide or ester, distinguishes area of metabolism) 3) Hydrophilic (ensures that drug will not precipitate in interstitial fluid/space) T or F: Local anesthetics are weak acids with a pKa of 7.5-9.5) - answerFALSE, LA are weak BASES with a pKa of 7.5-9.5) what determines the Non-Ionized (basic) % of anesthetic? - answer1) Tissue pH determines % of un-ionized LA 2) Dissociation Constant (pKa) determines % non-ionized LA T or F: Tissue acts as a buffer to convert cationic LA to its non-ionized base form - answerTRUE; Tissues have bicarbonate that raises the pH and makes LA more readily available in its unionized form what is the pKa of most LA's ? - answer1) the pKa of most LA's is between 7.5-9.5 T or F: Higher pKa means more non-ionized molecules and more effective diffusion - answerFalse; LOW pKa leads to more non-ionized particle and therefore more effective diffusion what is physiologic pH and why? how does this effect LA? - answer1) Physiologic pH is 7.4 2) Bicarbonate is a natural buffer 3) physiologic buffering makes LA MORE effective because it leaves more non-ionized form available What is the pH of a dental cartridge of lidocaine? How much is in non-ionized form at this pH? How then LA effective in these conditions? - answer1) pH 6 (of a lidocaine cartridge) 2) 1% of lidocaine is Non-ionized at this pH 3) Physiologic pH (bicarbonate) will make more non-ionized form readily available at physiologic pH, how much (in %) of non-ionized LA is available? - answer1) physiologic pH 7.4 2) 24% is non-ionized at this pH (due to bicarbonate in tissue) What environmental factors alter the effectiveness of LA and why? - answer1) Rapid Extrusion of LA....it increases volume of LA compared to available bicarbonate (slow extrusion is better!) 2) Infection, significantly lowers pH and therefore the ability to buffer LA, making less non- ionized form available what are the pKa's of Mepivicaine, Articaine, Lidocaine, Bupivicaine? - answer1) Mepivicaine 7.7 2) lidocaine 7.8 3) Articaine 7.8 4) bupivicaine 8.1 Which injection technique is most prone to hematoma formation? - answer1) PSA (infiltration is effective and does not pose the same risk) which anesthetic technique is more of a "pressure" anesthesia? - answer1) intra-pulpal injection What is the gauge of a yellow capped needle? a blue capped needle? which one has the largest diameter? - answer1) Yellow-27 Gauge 2) blue-30 gauge 3) yellow (27 gauge) has a larger diameter What are causes of "injection pain"? (list three) - answer1) Mechanical trauma (needle penetration) 2) Distention of tissue from LA 3) Anesthetic properties (Temperature, pH, etc) T or F: larger gauge needles are more painful? - answerFalse, in studies conducted, no discernible differences were found (LARGER gauge needles are recommended) How/Why is a larger gauge needles recommended for LA delivery? - answer1) Larger gauge needles are: a) Less likely to break b) easier to aspirate c) less likely to deflect (less fragile) what determines level/efficacy of anesthesia? - answer1) LA PROXIMITY to nerve 2) Degree of ionization