Basic Medical Sciences Relevant to Dentistry
What this domain tests
This domain checks whether you can apply foundational mechanisms to clinical dentistry rather than recall isolated facts. Expect integrated items on cell injury, inflammation, acid-base balance, pharmacokinetics, microbial virulence, and metabolic pathways that explain drug effects and disease risk.
Core rules and concepts
- Cell injury becomes irreversible when mitochondrial ATP production fails and membrane integrity is lost. Necrosis provokes inflammation; apoptosis is energy-dependent and generally non-inflammatory.
- Acute inflammation features vasodilation, increased vascular permeability, and neutrophil recruitment. Chronic inflammation features lymphocytes, plasma cells, macrophages, and fibrosis.
- The anion gap is Na minus (Cl plus HCO3), normally about 8 to 12 mmol/L. Metabolic acidosis with a high gap suggests ketoacidosis, lactic acidosis, renal failure, or toxins.
- First-order drug elimination removes a constant fraction per unit time; zero-order elimination removes a constant amount per unit time, as with ethanol and phenytoin at high doses.
- Glycolysis yields a net 2 ATP per glucose. Vitamin C is required for collagen proline and lysine hydroxylation, so deficiency impairs wound healing and periodontal integrity.
- Biofilm communities show reduced antibiotic susceptibility partly because of restricted diffusion and altered bacterial metabolism.
Worked example
A patient taking warfarin develops bleeding after a course of metronidazole. The reasoning is that metronidazole inhibits CYP2C9, reducing warfarin metabolism and raising the INR. This is a pharmacokinetic interaction, not a change in vitamin K intake. The safe response is to avoid the combination or monitor INR closely and adjust the warfarin dose; vitamin K is reserved for significant bleeding or a markedly elevated INR.
Traps that cost marks
Do not equate apoptosis with necrosis. Do not assume all antibiotics increase warfarin effect. Keep the compensation directions for respiratory and metabolic acid-base disorders distinct. Remember that zero-order drugs eliminate a fixed amount per time, not a fixed fraction. Finally, distinguish drug concentration from drug effect when protein binding or active metabolites are involved.