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4th year > 2020 F > Flashcards

2020 F Flashcards

1
Q

A 25-year-old male patient attends with irreversible pulpitis involving tooth 36 and requires root canal treatment. The patient is healthy and not on any medication. Radiographic findings reveal root canal curvature of the mesial roots of about 20 degrees.
List four problems that can occur when instrumenting a tooth with curved roots using only stainless steel ISO hand files. Give reasons for each of the problems. (4 marks)

A
  • Ledges - lack of coronal
  • Perforation - loss of working length &
  • Zipping - over preparation of the outer and under preparation of the inner curvature of the canal. Stainless steel wants to return to straight shape.
  • Blockage of the canal – dentine becomes extremely hard increasing the risk of the apex being transported. instrument seperation causing blockage.
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2
Q

Describe the process of canal shaping and cleansing (not obturation) using ProTaper Universal instrumentation of root canals. Assume that straight line access has been achieved and working length has been determined with a size 10 stainless steel hand file. Your apical finishing size should be 0.25mm. (6 marks)

A

(Assuming LA, DAM is also applied and an EWL has been obtained)
- ISO file 15 to 2/3rd estimated working length using watch winding
o Irrigation with NaOCL in leur lock syringe (with rubber stop) 🡪 recapitulation with ISO10 file 🡪 re-irrigate
- Protaper S1 to 2/3 estimated working length – shapes coronal 1/3rd of the canal watch winding
o You can take a radiograph +/- apex locator to get the correct working length at this stage then -1mm from it
- ISO 10 🡪 ISO 15 to Correct working length
- Protaper S1 to correct working length – shapes coronal 1/3rd of the canal balanced force
- Protaper S2 to CWL – shapes mid 1/3rd of the canal balanced force
- Protaper F1 to CWL – shapes apical 1/3rd of the canal (to ISO20) balanced forced
- Protaper F2 to CWL– shapes apical 1/3rd of the canal (to ISO 25) balanced force
o Ensure F2 is passive until it reaches apical 1/3 (tug back) and ISO25 binds coronally and mid root (tug back)
- Dry the canals with paper points moving onto master GP cone selection.
- Between each stage:
o Clean files 🡪 Irrigation with NaOCL in leur lock syringe (with rubber stop) 🡪 recapitulation 🡪 re-irrigate

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3
Q

Dental amalgam is a widely used restorative material. Several different amalgam products are available. With regards to “Non-γ2 amalgam”:

(a) Give two advantages, in terms of performance, of a non-γ2 amalgam.
(2 marks)

A
  • More corrosion resistant
  • Less creep
  • Higher mechanical strength
  • Better marginal seal
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4
Q

How does the manufacturer reduce γ2 from the structure of amalgam? (2 marks)

A
  • Addition of copper, above 6%, which reacts preferentially with tin meaning less is available to produce γ2.
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5
Q

With regards to “Zinc-free amalgam”:

(a)	Originally, why was it necessary for manufacturers to add zinc to amalgam alloy?							      (1 mark)
A
  • Scavenger, so it preferentially oxidises rather than the other constituents. prolonging the life of the material.
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6
Q

What effect could occur in a freshly placed amalgam restoration as a result of the presence of zinc in the amalgam alloy? (1 mark)

A

• Upwards and downwards expansion/pressure causing restoration to feel “high”

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7
Q

Explain the mechanism of zincs effect in amalgam restorations (3)

A
  • Zn + H2O 🡪 ZnO + H2 (Zinc can react with saliva/blood to form ZnO (slag) + Hydrogen gas)
  • H2 increases pressure which could cause the restoration to lift/raise this means it is less supported in these areas and more occlusal force is applied leading to a higher chance of deformation and fracture of the restoration
  • And/or the pressure causes trauma to the pulp leading to pulpitis.
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8
Q

What is the main symptom that the patient could experience if zinc is present in their amalgam restoration?

A

pain

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9
Q

Name two different patterns of bone loss (1)

A

Vertical & horizontal

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10
Q

How can inter-proximal bone defects be classified in general?

A
  • 1, 2, 3, wall defects
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11
Q

Following hygiene phase therapy a patient’s oral hygiene was excellent but pockets of >6mm persisted in the lower right quadrant. Open flap debridement was performed:

(a) Why does furcation involvement limit the success of this treatment? (1 mark)

A
  • Involvement/bone loss of the furcation which is hard to clean and lowers prognosis/ longevity of the tooth
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12
Q

best possible clinical and radiographic outcomes for hygiene phase therapy/open flap debridement in terms of the healed situation. (3 marks)

A
  • Plaque = <15%, BOP = <10% and pockets <4mm
  • no increase in bone loss
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13
Q

(c) Give two alternative options other than open flap debridement for the management of periodontally compromised 47 which has furcation involvement (2)

A
  • Guided Tissue/Bone regeneration
  • Furcation - tunelling
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14
Q

A middle-aged gentleman attended your surgery with the metal ceramic crown from his upper right central incisor in his hand. He has no pain. You notice that the dentine core has fractured off inside the crown. There is no history of previous root canal therapy.

1 What four features of the remaining tooth tissue of the central incisor might indicate whether it can be successfully restored or not? (4 marks)

A
  • Tooth tissue remaining - Ferrule – more than 2mm, crown:root min 1:1
  • Quality of tooth tissue remaining
  • Mobility (more or less than normal)
  • Type of fracture (is the pulp involved and is it still vital)
  • can moisture control be maintained
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15
Q

A middle-aged gentleman attended your surgery with the metal ceramic crown from his upper right central incisor in his hand. He has no pain. You notice that the dentine core has fractured off inside the crown. There is no history of previous root canal therapy.
2 The tooth is restorable; list and briefly describe 3 ways in which the space can be restored in the short term. (6 marks)

A
  • Re-bond the fractured MCC – temporary measure
  • Vacuum formed splint holding the MCC in place – keeps the teeth in place preventing them tipping
  • Overdenture – keep the space by covering the teeth
  • preformed MC
  • Protemp crown made with putty matrix
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16
Q

A 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.
What supporting components would you use? List the type, tooth (FDI) and surface. (3 marks)

A
  • 34 mesial rest seat – RPI
  • 43 cingulum rest seat
  • 47 mesial rest seat
17
Q

A 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.
List the retentive components that you would use. Indicate component name, what tooth (FDI) and position if appropriate. (3 marks)

A
  • 34 and 44 gingivally approaching I-bar
  • 47 circumferential ring clasp
18
Q

A 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.
Name the major connector(s) and state the reasons for your choice including the choice of material. (3 marks)

A
  • Lingual bar – easier to clean gingival margins as they are not covered
  • Cobalt Chromium (CoCr)
19
Q

A 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.
Which feature of your design would provide indirect retention? (1 mark)

A
  • 44 - distal rest
20
Q

In terms of complete dentures what is meant by the following terms; stability

A
  • resistance to occlusal directed forces (towards the gums)
21
Q

In terms of complete dentures what is meant by the following terms; retention

A
  • Resistance to vertical displaced forces (away from the gums)
22
Q

How do you achieve adequate retention in a conventional complete upper denture? (3)

A
  • Peripheral seal
  • Post dam
  • Full extension into buccal sulcus
23
Q

In terms of biometric principles where are denture teeth located on (a) the upper denture?

A
  • Buccally to the ridge
24
Q

In terms of biometric principles where are denture teeth located on (b) the lower denture

A
  • On the ridge
25
Q

Your VT trainer uses a conventional Glass Ionomer as his lining material. It is dispensed as a powder and liquid and hand mixed by his nurse. You want to use the Resin Modified Glass Ionomer Cement (RMGIC) lining material you have used previously in the dental hospital (Vitrebond). You wish to persuade him to change to your preferred material.
1 What are the advantages of the material you want to use? (3 marks)

A
  • RMGIC has resin particles therefore:
    o Higher mechanical strength
    o Lower solubility than GIC
    o Command set via light
26
Q

Why is it wrong to use a glass ionomer filling material as a luting agent?

A
  • May absorb moisture
  • Weak mechanically – prone to caries ingression
27
Q

Which luting agent would you use to cement the following restoration: (a) A Metal Post and Core

A
  • GIC
28
Q

Which luting agent would you use to cement the following restoration (b) A Porcelain Veneer

A
  • Resin luting cement with silane coupling agent
29
Q

Which luting agent would you use to cement the following restoration (c) A Fibre Post

A
  • Dual cure composite resin cement
30
Q

A 43-year-old man attends your surgery with severe toothache. He admits that he is not a regular attender and knows he has neglected his teeth. Clinical examination reveals many broken restorations and carious cavities. The pain is associated with his lower left second molar (37) which is tender to percussion.
Specify three questions you would ask this patient that may lead you to a diagnosis of the cause of the pain from tooth 37. (3 marks)

A

Pain history
- Site of pain (localised or not), onset (when did it start/how frequent is the pain)
- Characteristics of pain (how the pain feels, duration and is it keeping them up at night)
- Factors which help relieve/exacerbate the pain (do analgesics help, worse with cold/heat)

31
Q

Give four reasons why non-surgical therapy may fail to eliminate bacteria from periodontal pockets? (2 marks)

A
  • Pockets may be blocked (e.g. healed over or calculus) so unable to remove bacteria
  • Instruments may not reach depth of the pockets as they are too big therefore do not disrupt the biofilm
  • Depend on patient compliance and skill set – patient may not comply with the regime or be able to carry it out adequately
  • Depends on clinicians’ skills – may not carry out non-surgical therapy adequately
32
Q

List three potential problems that limit the usefulness of oral antibiotics in the treatment of periodontitis.

A
  • Antibiotics may be unable to penetrate the biofilm
  • Antibiotics may not reach those sites
  • Chance of developing antibiotic resistance
33
Q

You are seeing a patient with a lateral periodontal abscess in tooth 22, they have accompanying systemic symptoms. The patient is keen to keep the tooth, describe how you should manage it. (5 marks)

A
  • Incise and drain abscess or drain through pocket (LA if needed)
  • Supra and sub gingival scaling slightly short of the base of the pocket
  • HPT: OHI, TBI, Interdental cleaning,
  • Post op instructions – analgesics for pain relief – whatever the patient normally takes (e.g. Ibuprofen)
    o As systemic symptoms can prescribe antibiotics – check if allergic/taking any already
    ▪ Amoxicillin capsules 500mg, to take 3xdaily for 5 days (total 15 capsules)
    o If allergic can take:
    ▪ Metronidazole tablets 200mg, to take 3xdaily for 5 days (total 15 tablets)
  • Assuming I’ve reassured, gained consent and recorded in my notes
34
Q

Other than replacement dentures, state two other treatment methods which can be used by a dentist to improve retention and stability in a loose complete denture in an edentulous patient.
(2 marks)

A
  • Reline
  • Rebase
35
Q

Describe, briefly, three important features of complete dentures that you would check during the try-in stage of complete dentures. (3 marks)

A
  • Extension, retention, stability
  • Tooth position: LIMBO
    o Lip line/level
    o Incisal edge on show
    o Midline
    o Buccal corridor
    o Occlusion – OVD, RFH, FWS
  • Patients thoughts
36
Q

You have just completed surgical removal of tooth 37 which fractured during an attempted forceps extraction. Your patient is a 21-year-old male with poorly controlled asthma. You intend to prescribe analgesia for the patient.
Name a suitable analgesic for this patient that you are allowed to prescribe on an NHS prescription. (1 mark)

A
  • Paracetamol
37
Q

You have just completed surgical removal of tooth 37 which fractured during an attempted forceps extraction. Your patient is a 21-year-old male with poorly controlled asthma. You intend to prescribe analgesia for the patient.
Which group of analgesic drugs would you avoid in this patient?
(1 mark)

A
  • NSAIDs

4th year (4 decks)

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