Endodontics 4th year Flashcards
What are potential diagnoses of a radiolucent lesion of endodontic origin?
- Apical periodontitis (acute/chronic)
- Periapical cyst (continuous with root canal system)
- Periapical abscess
What are the biological reasons for persistent periapical pathology?
- Microbial causes: persistent or re-introduced infections
- Extraradicular infection: e.g. abscess with large microbial challenge may leave behind residual bacteria which can cause continuous infection
- foreign body reaction: extrusion of medicaments or debris during RCT
- true cystic lesions - cannot be treated with RCT, requires surgical intervention
- periapical scar formation: granulation tissue replaces bone
What are the two types of peri-apical cysts, and what are they caused by and how does treatment differ?
- Periapical cyst (true cyst) - is not associated with the root canal system as it is completely encapsulated. Infection from the root canal system leads to inflammation of the peri-radicular tissues. If there are epithelial cell rests of Malassez present within the periodontal ligament which are stimulated, a cyst can form. Apical surgery is required to remove the cystic lesion, as RCT will not resolve the lesion
- Periapical cyst (Pocket) - is continuous with the root canal system. It will resolve with endodontic therapy with no surgical intervention required. It is caused by the same way as a true periapical cyst.
How to differentiate apical scar from apical periodontitis?
Diagnosis of apical scar:
- asymptomatic (no TTP)
- non-progressing lesion - stays the same size
- is associated with a well-performed RCT and good coronal restoration
Why might someone with a potentially cracked tooth find it difficult to isolate which tooth is causing pain?
The crack may be causing pulpal pain. As the periodontal ligament does not have any inflammation, it will be difficult to isolate the offending tooth due to lack of proprioceptors in the pulp.
Why may it be difficult to anaesthetise a patient that is in pain?
- low tissue pH in infected tissues, preventing basic LA solution to work effectively
- Accessory innervation
- hyperalgesia: patient has low tolerance to pain
- peripheral sensitization: nerves have reduced threshold to fire pain signals
- central sensitisation
- operator error - poor technique or improper nerve block chosen
What are operator factors which may lead to persistent periapical infection?
- poor coronal seal following root canal treatment
- inadequate obturation, allowing bacteria to easily reinfect the canals and peri-radicular tissues
- inadequate chemomechanical prepration - leaving behind biofilm within the canal space
- Missed canals - e.g. MB2 and lateral/accessory canals
Why is episodic pain experienced clinically in patients with pulpitis?
Episodic pain occurs due to a cycle of inflammation and necrosis that occurs in pulpal tissue. Intrapulpal inflammation occurs which leads to reduced blood flow (ischaemia) in the region, causing severe pain followed by necrosis (absence of symptoms).
Absence of symptoms may also occur due to the formation of a sinus tract
How to diagnose a vertical root fracture?
- tooth will be TTP
- likely non-vital tooth
- radiographic evidence of bone loss - can be in periapical region or along the lateral borders of the root
- deep periodontal pocket associated with bone loss
- sinus tract traced with GP point to site of fracture
- symmetrical space between GP and post may indicate a vertical root fracture
What are the possible sequelae of traumatic tooth injuries?
- pulpal necrosis
- bone loss (apical or marginal)
- coronal discolouration
- root canal obliteration
- external inflammatory root resorption
- internal resorption
- replacement resorption
What are the possible healing responses to horizontally fractured teeth?
- calcified union (bone between both segments)
- bone and connective tissue healing
- connective tissue healing
- failure to heal - resorption occurs
How to clinically diagnose craze lines and cracks?
- transillumination
- methylene blue dye for cracks
- superficial cracks can usually be seen visually, especially adjacent to amalgam restorations
How to differentiate craze lines and cracks with transillumination?
- craze lines will allow for complete light to pass through the tooth
- cracks will not allow light to propagate further than the crack line
What medicament is placed in canals for teeth that have been avulsed and why?
Calcium hydroxide - it has been shown to prevent external inflammatory root resorption
What are the management guidelines for an avulsed tooth with an open apex that has an extraoral dry time >60 minutes?
Due to very low chance of revascularisation:
1. take a radiograph of the socket to assess for bone fracture or foreign bodies
2. remove necrotic soft tissue around root with gauze
3. perform extra-oral RCT + apexification
4. administer LA
5. irrigate socket with saline + reposition bony fragment (if present)
6. replant tooth slowly with digital pressure
7. verify correct position of tooth with PA radiograph
8. suture any gingival lacerations
9. flexible splint for 4 weeks, or 6-8 weeks if bone fracture present
10. administer systemic antibiotics - tetracycline (doxycycline) for patient >12 years, amoxicillin for patients <12 years
11. recommend Tetanus booster if was a ‘dirty’ avulsion where tooth was dropped into e.g. soil
12. clinical and radiographic follow up 4 weeks, 3 months, 6 months, 1 year, then every year
HIGH CHANCE OF INFLAMMATORY REPLACEMENT RESORPTION
