Working length
Working length
• Distance between referential point on
tooth crown an apical constriction
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Apical morphology
1. X-ray apex
2. Apical foramen
3. Apical constriction
4. Periodontal ligament
5. Root cementum
6. Dentin
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Apical constriction
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Why RTC terminates in apical
constriction?
• Small apical communication
• Less risk of damage pof periodontium
• Prevention of overfilling
• Prevention of apical transport of infected metarial
• Possibility of good removal of debris
• Good compaction of guttapercha
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X-ray apex
Skutečnost
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Principle of apexlocators
• Endometrie
mearurement of impedance
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X- ray method
X-ray with root canal instrument (ISO 15 no smaller because of x ray contrast)
Introduced to the safe length – this length have been measured on many teeth,
we know this length for each tooth)
Take x- ray using the rubber stop at the referential point.
If there difference no more than 2 mm we can measure the working length, if more –
new x ray with instrument thai is introduced deeper.
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