Question 41 (part 2) · LDEK · Irrigation and intracanal medicaments
Calcium hydroxide dissociates to Ca2+ and OH-ions after mixing it with water, which causes the permanent increase of alkaline reaction of non-hardening paste applied to the canal. Indicate true statements regarding the mechanism of action of such paste in the canal:
1) immediately after applying, saturation of the dentine with OH-groups and destroying of microorganisms present in dentin tubules occurs;
2) mechanism of OH-groups action consists in damaging the bacteria cell walls and destroying its protein structures;
3) Ca(OH)2 pastes are significantly inactivated by organic residues;
4) immediately after applying OH-ions do not infiltrate deep into the dentin, due to the dentine’s hydroxyapatites, which possess buffering capacity;
5) organic residue in the canal are easier to remove after Ca(OH)2 application, not only by rinsing solutions, but also hand instruments.
Correct answer is:
2) mechanism of OH-groups action consists in damaging the bacteria cell walls and destroying its protein structures;
3) Ca(OH)2 pastes are significantly inactivated by organic residues;
4) immediately after applying OH-ions do not infiltrate deep into the dentin, due to the dentine’s hydroxyapatites, which possess buffering capacity;
5) organic residue in the canal are easier to remove after Ca(OH)2 application, not only by rinsing solutions, but also hand instruments.
Correct answer is:
- A. 1,2,4.
- B. 2,3.
- C. 2,4.
- D. 3,5.
- E. 2,4,5.
Hint
Think about how fast hydroxyl ions actually diffuse through dentin and what dentin hydroxyapatite does to them.
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