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
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- 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
* 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
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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 - mesial 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 – occlusal 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
identify anatomical landmarks
- A = incisive papilla
- B = maxillary tuberosity
- C = palatine fovea
complete dentures
stability
- resistance to vertical forces towards the mucosa
complete dentures
retention
resistence to verical displaced forces (away from gum)
how to achieve adequate retention in conventional complete upper denture
peripheral border seal
post dam
extentsion into depth of sulcus and posterioly hamular notch
terms of biometric principles where are denture teeth located on upper denture
buccal to ridge
terms of biometric principles where are denture teeth located on lower denture
on the ridge
fit and healthy 32 year-old patient requires surgical removal of his LL8
very anxious and has opted to have the tx under IV sedation
Why is written consent required in advance of the treatment day in sedation?
To give them time to review their decision and IV sedation drug has amnesia as a side effect so will not remember the consent on the day
drug would a UK-trained dentist select to sedate the patient via an intravenous route (1 mark)? What preparation of this drug should be used
(1 mark)?
Midazolam 5mg/5ml - 2mg bolus titrated in 1mg increments every minute after that
vital signs to record before/during/after IV sedation
heart rate
blood pressure
oxygen saturation
in the event of over seadtion what drug to use to reverse this
flumanzenil
instructions to pt post IV sedation for min 12hours after discharged from care
- Do not make any important decisions – signing legal documents, buying things, etc
- Do not drive/operate any heavy machinery
- Rest
patient has sustained a displaced fracture of the right body of the mandible.
other than pain, bruising and swelling name other clinical signs/symptoms commonly seen in this injury
occlusal step deformity
bleeding
AOB
mobile teeth
altered occlusion
trismus/limited opening/function
numbness to lower lip
facial asymmetry
two most appropriate standard radiographic views that may help in establishing the diagnosis of a mandibular fracture
- OPT
- PA manidble
other options -
a. Occlusal
b. Lateral oblique
c. Town’s view (subcondylar)
d. SMV
e. CT scans – mainly now or CBCT (3D images best)
3 factors that can cause displacement of fracture
opposing muscle attachments
direction of fracture line and force of impact
opposing occlusion
3 tx options for a fractured mandible
leave and monitor
Open reduction and internal fixation ORIF
intermaxillary fixation
35-year-old male presents with pain, swelling and pus discharge around a partially erupted lower right wisdom tooth.
feels slightly unwell and has some mild facial swelling.
six features you would specifically consider, relating to the patient’s history, extraoral examination or investigations
Full medical history ( DIABETIC/IMMUNOSUPPRESED, Medications - anticoag or platelet, allergy - antibiotics
pain history - SOCRATES
* Have they had this pain before? If so when and how many times
* When did it start?
* Has the swelling increased since then?
* Pain severity during this period
* When did you start to feel unwell – coincide or later/early
* Pain relief – do they help
E/O
* asymmetry,
* assess structures nearby – is it a airway risk and swelling across midline or FOM involved
Investigations
* right side OPT
two main nerve branches at risk of damage during removal of lower wisdom teeth and which structures would be affected in the event of such damage?
lingual nerve
inferior alveolar nerve
appropriate immediate management of
35-year-old male presents with pain, swelling and pus discharge around a partially erupted lower right wisdom tooth.
feels slightly unwell and has some mild facial swelling.
LA
Incise and drain abscess
Antibiotics – as systemic involvement
* Phenoxymethylpenicillin 250mg tablets 2 tablets 4xday for 5days
Post op instructions and follow up – review in 1 week with discussion to extract
* If swelling crosses midline or eye involvement or airway obstructed advise to go to A&E
patient presents with an exophytic, slow growing lesion on the right labial commissure.
differential dx (2)
verrucous carcinoma
squamous cell carcinoma
suspected that the lesion is malignant,
name three histological features that need to be identified in the biopsy
pleomorphism
hyperchromatism
cellular atypia/atopic mitotic bodies
different clinical presentations of oral squamous cell carcinoma.
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raised rolled border
indurated
ulceration
non-homogenous
bleeding/erythematous
pathology report comes back stating that the lesion is benign.
What do you think may have caused this growth to appear?
Herpes papilloma virus Infection / Immunocompromised
How would you confirm the presence of the aetiological agent
Biopsy – send to lab for histology and definitive diagnosis
??
From which part of the orofacial structures is it most common to take a salivary gland biopsy as part of the investigation of suspected Sjögren’s syndrome?
labial gland
two features on the histological examination of this sample that would be compatible with Sjögren’s syndrome as a clinical diagnosis
- Lymphocyte concentration – 50+ per mm2
- Acini atrophy
Focal swelling in the major salivary glands is usually associated with salivary malignancy. What feature in relation to a parotid gland lump may suggest a malignant rather than a benign tumour?
Numbness in part of your face, lymphandenopathy and fixed persistent hard lump
most common salivary gland tumour in parotid gland
pleomorphic adenoma
most comon salivary gland tumour of upper lip
- Acinic cell adenocarcinoma
- adenoid cystic carcinomas
pleomorphic adenoma
most comon salivary gland tumour of upper lip
- Acinic cell adenocarcinoma
- adenoid cystic carcinomas
pleomorphic adenoma
most common salivary gland tumour of soft palate
mucoepidermoid carcinoma
pleomorphic adenoma
two ways that the skeletal base relationship may be assessed clinically in the anteroposterior plane
- Visually
- Clinically Palpate skeletal bases
describe class 1 skeletal base.
mandible is 2-3mm posterior to maxilla
Cephalometric analysis reveals that a patient has an ANB angle of 8 degrees. What does this suggest about their skeletal pattern?
Class 2 – maxillary incisors are anterior to mandibular incisors
2-4 class I
>4 class 2
Below 2 is class 3 - Below 0 severe class 3
120/80 for max inc Ui/Li
two ways that the skeletal pattern can be assessed clinically in the vertical plane.
- Use Frankfort Mandibular Plane Angle
- Upper Anterior Face Height :Lower Anterior Face Height
describe class III incisor relationship
mandibular incisors lie anterior to the cingulum plateau of the maxillary incisors
What is a balancing extraction and why might you consider a balancing extraction?
hen the same tooth on the opposite side of the arch (contralateral) is also extracted
Used to prevent a shift in the midline e.g. primary canines
child presents with the upper left permanent central incisor in crossbite.
ideal time to tx this malocclusion
as soon as problem has been detected
3 features of upper left permanent central incisor in crossbite that make it favouravke for tx with removable appliance
- Single tooth so anchorage ok
- adjusted via tipping movement alone (so no bodily movement require)
- due to anterior cross bite, can use posterior bite plane needed to create AOB to tip tooth forward which can be done by URA
design URA for
upper left permanent central incisor in crossbite.
Aim - please construct URA to correct 21 crossbite
Active component
* Z-spring 0.5mm H.S.S.W (Hard stainless steel wire) palatal on 21
Retentive components
Adams clasps in:
* 0.7mm H.S.S.W on 16, 26
* 0.6mm H.S.S.W on 54, 64 (URD, ULD)
Anchorage considerations
* Present
Baseplate modifications
* Self-cured PMMA with Flat Posterior Bite Plane
alt active component for ant crossbite
z spring
T spring
13-year-old female patient with discoloured upper incisors is very upset by the appearance of these teeth - affecting her at school and she won’t smile.
Apart from the discolouration she is clinically symptom free and the teeth are vital.
What baseline information and/or special tests would you undertake pre-treatment?
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- SHADE assessment –draw out the teeth and areas of discolouration on them and shade of different areas of the teeth and lesions.
- Take photographs
- sensibility scores
- Record in notes and get patient/parent/guardian (legally) to sign this off saying they agree with the current shade the teeth are.
Assuming this has been done:
- Full history (C/O, HPC, M/H with medications and allergies, D/H, S/H, F/H, E/O and I/O)
- PGI, BPE (if necessary 6PPC), charting
- Radiographs – Periapicals of upper incisors
stages of microabrasion
- PPE for operators and patient
- Clean with plain pumice teeth
- Vaseline applied to the gingiva
- Dental dam – wedjets ensure whole tooth is visible
- Sodium bicarbonate guard placed around the margin of the area the dam and tooth meet
- Mix pumice with hydrogen chloride acid (18%) and Place on slow speed (special rubber cup slowly rotating) Apply to tooth rubbing in for 5seconds, Wash off, dry and assess colour
- reapply sodium bicarbonate guard (1cycle) and Repeat for max of 10 cycles
- Once finished, remove dental dam and apply fluoride toothpaste.
- Use the finest soft flex disc to remove the prism free the layer at top
% of hydrochloric acid for microabrasion
18%
pt information for after microabrasion
- Post op instructions – warn patient not to eat or drink highly coloured substances as they can stain the teeth for first 24hrs as teeth are dehydrated (poss up to 1 week)
- Warn re sensitivity – Sensodyne toothpaste
- Review appointment roughly 6-8 weeks to assess difference