2020 Flashcards
problems that can occur when instrumenting a tooth with curved roots using only stainless stell ISO hand files
and reasons for each of the problems
6
- perforation - due to root curvature and pressure of instrumentation
- fracture of instrument - due to cyclic fatigue and torsional stress
- failure of reach CWL - due to curved canal
- blockage of canal - due to not being able to flush/irrgate effectively due to curvature of apex
- instrument can be locked in canal if use too large an instrument for canal to be shaped
- zipping - over preparation of the outer curvature and under preparation of the inner curvature of the canal
Describe the process of canal shaping and cleansing (not obturation) using ProTaper Universal instrumentation of root canals.
Your apical finishing size should be 0.25mm.
straight line access achieved; WL determined with size10 StSteel file
ISO file 15 to 2/3rd estimated working length using balanced force technique (90 degrees clockwise with apical pressure, Continue apical pressure and turn file 180 degrees counter clockwise)
* Irrigation with NaOCL in leur lock syringe (with rubber stop and use index finger), recapitulation with ISO10 file re-irrigate
Protaper S1 to 2/3 estimated working length – shapes coronal 1/3rd of the canal
* You can take a radiograph +/- apex locator to get the correct working length then -1mm from it (size 10 for locater and size 15 radiograph)
ISO 10 and then ISO 15 to Correct working length
Protaper S1 to correct working length – shapes coronal 1/3rd of the canal
Protaper S2 to CWL – shapes mid 1/3rd of the canal
Protaper F1 to CWL – shapes apical 1/3rd of the canal (to ISO20)
Protaper F2 to CWL– shapes apical 1/3rd of the canal (to ISO 25)
* Ensure F2 is passive until it reaches apical 1/3 (tug back) and ISO25 binds coronally and mid root (tug back)
Irrigation protocol (30ml or 10mins NaOCl, then dry thoroughly penultimate 1min rinse EDTA then dry again and then final rinse NaOCl – cannot make them mix as brown precipitate)
Dry the canals with paper points moving onto master GP cone selection.
Between each stage:
* Clean files 🡪 Irrigation with NaOCL in leur lock syringe (with rubber stop) 🡪 recapitulation 🡪 re-irrigate
adv of non-γ2 amalgam
4
more corrosion resistant
less creep
higher mechanical strength earlier
inc durability of margins
how does manufacturers reduce γ2 from the structure of amalgam
high copper content - more than 6%
originally, why was it necessary to add zinc to amalgam alloy
scavenger - so it preferentially oxidises rather than its constituents
what effect could occur in a freshly placed amalgam restoration due to presence of zinc in amalgam alloy
expansion
explain the mechanism of expanion in fresh placed zinc containing amalgam alloy
interaction of unreacted zinc with saliva/blood -
Zn + H2O -> ZnO + H2
bubbles of H2 formed within amalgam
pressure build up causes expansion
* downward pressure cause pulpal pain
* upward - restoration sitting proud of surface
main symptom experienced in zinc expansion of amalgam
pulpal pain
33-year-old patient presents with a discoloured upper left central incisor tooth
no caries or restorations of any kind in any teeth and is fit and healthy.
The discolouration, first noticed two years ago, has been getting steadily worse.
no symptoms, and the patient is concerned with the appearance.
He recalls a blow to the tooth when playing sport a few years previously
how to determine aetiology of discolouration
thorough pt histroy - medical, dental, social, trauma
radiographic assessment (Periapical)
sensibility tests
3 sequelae of dental trauma that may influence you tx planning for this tooth
- pulpal status of tooth - nonvital or necrotic possibility
- periapical pathology present
- mobility of tooth - excessive or ankylosis
2 restorative procedures that can be carried out to improve aesthetics of discoloured tooth post trauma
describe them
external vital bleaching
* bleaching trayma with well for the affected tooth to place hydrogen peroxide or carbamide peroxide in to be used overnight for 2 weeks (initial shade taken prior to compare with at review)
indirect/direct composite veneer
* composite layer on top of minimally prep tooth to mask discolouration
2 patterns of bone loss in this PA
horizontal and vertical
explain the development of the bone loss on the mesial aspect of the lower right second molar
- plaque present in deep pocket mesial to 47, which generates inflammation and zone of destruction causing bone loss but due to distance and thick bone between 47m and 46D a vertical bony defect created as the zone of destruction is narrower than the width of bone/space
- exacerbated due to the morphology of the mesial root – sharp curve/dilaceration and horizontal bone loss
*Thick bone between teeth more likely vertical bony defect (teeth further apart); central bone survives
Thin bone/close teeth more likely horizontal *
how can inter-proximal bone defects be classified in general?
1, 2 or 3 wall defects
Following hygiene phase therapy this patient’s oral hygiene was excellent but pockets of >6mm persisted in the lower right quadrant. Open flap debridement was performed
feature of this patient’s disease, observable on the radiograph, is most likely to limit the success of this treatment and why?
involvement/bone loss to furcation
which is hard to clean and lowers prognosis/longevity of tooth
best possible clinical and radiographic outcomes for open flap debridgement in terms of the healed situation
Plaque = <15%, BOP = <10% and pockets <4mm
2 alternative options for management of 27 other than open flap debridement
- Guided Tissue regeneration
- Furcation - Tunnelling
middle-aged gentleman attended your surgery with the metal ceramic crown from his upper right central incisor in his hand. He has no pain.
The dentine core has fractured off inside the crown.
no history of previous root canal therapy.
4 features of the remaining tooth tissue of the central incisor might indicate whether it can be successfully restored or not
- tissue remaining - ferrule (2mm circumferential dentine)
- quality of remaining tissue (caries)
- fracture extension - if pulpal involvement or root fracture
- mobility
middle-aged gentleman attended your surgery with the metal ceramic crown from his upper right central incisor in his hand. He has no pain.
The dentine core has fractured off inside the crown.
no history of previous root canal therapy.
tooth is restorable - list and briefly describe 3 ways the space can be resotred in the short term
- Splint MCC onto adj teeth – composite and SS passive wire
- Vacuum formed retainer with pontic in place of tooth
- Use of prefabricated temporary crown cemented on
patient has the following missing teeth: 38, 37, 36, 35, 45 and 46.
You decide to provide a definitive removable partial denture. The patient has a well maintained mouth with no active disease and you can assume has suitable survey lines.
supporting components would you use? List the type, tooth (FDI) and surface
34 – RPI – mesial rest seat
43 – cingulum rest
47 - distal rest
patient has the following missing teeth: 38, 37, 36, 35, 45 and 46.
You decide to provide a definitive removable partial denture. The patient has a well maintained mouth with no active disease and you can assume has suitable survey lines.
retentive components that you would use. Indicate component name, what tooth (FDI) and position if appropriate
34 – RPI – gingival I bar clasp
44 – gingival clasp
47 – circumferential ring clasp ( or occlusally approaching self reciprocating)
patient has the following missing teeth: 38, 37, 36, 35, 45 and 46.
You decide to provide a definitive removable partial denture. The patient has a well maintained mouth with no active disease and you can assume has suitable survey lines.
major connector(s) and state the reasons for your choice including the choice of material.
Lingual bar – need 5mm from margin to bar, 2mm for bar, 1mm to FOM
able to clean gingival margin so maintain OH better
Cobalt chrome CoCr
patient has the following missing teeth: 38, 37, 36, 35, 45 and 46.
You decide to provide a definitive removable partial denture. The patient has a well maintained mouth with no active disease and you can assume has suitable survey lines.
feature of design that would provide indirect retention
43 cingulum rest
identify anatomical landmarks
- A = incisive papilla
- B = maxillary tuberosity
- C = palatine fovea