restorative dentistry Flashcards
- You decide that this image, whilst not perfect, is adequate as it is diagnostically acceptable. Describe how this collimation error has occurred.
collimation = cone cutting
incorrect alignment between x-ray tube and receptor holder
or incorrect orientation of the rectangular collimator
- What fault can be observed in the amalgam restoration in tooth 16? (1 mark)
overhang mesially
- What faults in the placement of the restoration are likely to have led to this problem?
(2 marks)
matrix band placement - nit adequately adapted
amalgam not condensed in
- What problems could this give rise to, in the short and long term? (4 marks)
plaque trap
gingiva
pain when chewing
increased attachment loss
secondary caries
difficulty cleaning
- List TWO ways to correct this situation. (2 marks)
remove all overhang
re do restoration
- The diagram below represents Posselt’s envelope of mandibular movement in the sagittal plane.
RCP
retruded contact position (RCP)
mandible to maxilla when the mandibular condyles are in their most superior and anterior position, independent of tooth contact
- What name is given to the position of the mandible at point 1?
(1 mark)
ICP
intercuspal position (ICP)
“best fit” between upper and lower teeth
- Point 7 may be referred to as the mandibular rest position. Clinically the distance between point 7 and point 1 is referred to by what term? (1 mark)
freeway space
space between the upper and lower dental arches when the mandible (lower jaw) is in its relaxed, or resting, position and the teeth are not in contact (intercuspal position).
In a relaxed upright patient what is the average distance in millimetres between points 7 and 1?
(1 mark)
2-4 mm
- The mandible is said to be on its “retruded axis” when it occupies any position between points: (underline, circle or make bold the correct answer)
1 and 2
5 and 6
2 and 6
3 and 4
5 and 4
(1 mark)
5 and 6
- The retruded axis is said to be a border position of the mandible. What is a border position? (1 mark)
represents most retruded or posteriorly located position of the mandible
- Why is the retruded axis important in clinical dentistry? (1 mark)
reference point for mounting casts
occlusal analysis
stable and reproducible
treatment planning
diagnosis of TMJ disorders
- What TWO records are required for mounting casts on a semi adjustable or average value articulator? (2 marks)
centric relation (CR) record = relationship between maxilla and mandible when condyles are most retruded
face-bow transfer = maxillary arch to TMJ
Herbert Schilder described in 1974 the concept of chemomechanical disinfection. In his paper he outlines design principles that should be applied during root canal shaping.
1. Name the design principles outlined by Herbert Schilder. (3 marks)
- create a continuously tapering funnel shape
- maintain apical foramen in original position
- keep apical opening as small as possible
Based upon anatomical studies by authors such as Vertucci, it is apparent that root canal anatomy can be very complex (image below). It is because of this that mechanical debridement alone cannot achieve disinfection of the root canal space. In order to support mechanical debridement irrigants are used to achieve disinfection.
- Besides disinfection of the root canal space name TWO other objectives of irrigant use in root canal treatment? (2 marks)
removal of debris
dentin smear layer removal by acting on organic components
enhancement of biofilm disruption
dissolve pulp remnant
- What is the ideal primary endodontic irrigant AND at what concentration range is it most effective? (2 marks)
sodium hypochlorite (NaOCl)
used between 1-6% = parcan in GDH - 3%
- Name THREE factors important for the function of this primary endodontic irrigant? (3 marks)
antimicrobial efficacy
tissue dissolution ability
biocompability = minimise inflammation and irritation
concentration, volume and contact and mechanical agitation, exchange
- name problems with NaOCl (3 marks)
possible effect on dentine properties - dissolves collagen fibres in dentine
inability to remove smear layer by itself = use EDTA 17% with NaOCl
effect on organic material - dissolution of mineral components = becomes weaker
- name 4 irritant complications
fabric discolouration
ophthalmic injuries due to eye contact
apical extrusion leading to tissue necrosis
allergic reactions
He is complaining of symptoms from the left side of the mandible.
He reports pain when eating and also when drinking hot or cold fluids. The pain on hot or cold only lasts for seconds. He is unsure which tooth is causing which symptom. You have taken a periapical radiograph of the teeth.
Using the photograph and radiograph provided, answer the following questions. Answers provided must be in FDI notation.
- Which teeth are likely to be responsible for his symptoms?
(2 marks)
36 and 37
- What quality rating would you give this radiograph and why?(1 mark)
diagnostically acceptable
can see right structures - apices of 36 and 37
Give THREE important relevant clinical findings from the clinical photograph.
(3 marks)
Massive carious lesion in the 36 - half of crown is missing, brown and black in colour, lost disto-buccal and disto-lingual cusp
Staining in the pits and fissures of the 37 and the enamel is dark in colour disto-occlusally- suggesting a carious lesion.
The 47 looks to be darker in colour disto-occlusally and stained fissures- perhaps carious too.
darkening of buccal pit
- Give THREE important relevant radiographic findings. (3 marks)
apical radiolucency 36, 37
37 - disto-occlusal caries extended into dentine, appearing close to pulp
unrestorable 36 - large grossly carious lesion d/b/p, extended into the pulp
- Describe TWO further clinical investigations (other than radiography) which you would undertake to assist in your diagnosis.
(2 marks)
electric pulp sensibility testing
cold sensibility test
percussion and palpation
- Looking at the photograph and radiograph, which tooth would you expect to be responsible for each of:
(2 marks)
i. Sensitivity to hot and cold?
AND
ii. painful to pressure when eating?
i) 37
ii) 36
- For the tooth which is painful to pressure on eating what TWO diagnoses can be made?
(2 marks)
symptomatic apical periodontitis
irreversible pulpitis
- What treatment would be the most appropriate for this tooth? (1 mark)
extraction
- For other molar tooth what two diagnoses are appropriate?
normal apical tissues
systematic reversible pulpitis
- what treatment would be most appropriate for this tooth?
RCT with composite
- A patient presents with a 7 mm pocket that is discharging pus, on the mid-buccal aspect of tooth 26. The tooth is non-vital and there is very little pathological periodontal pocketing elsewhere in the patient’s mouth.
i) What is the most likely diagnosis from the above list? (1 mark)
periapical abscess
ii) Give TWO anatomical factors that may be responsible for the location of the discharging pocket? (2 marks)
root canal anatomy
proximity to apical foramen
iii) What treatment would you perform? (3 marks)
RCT
excision and drainage
if systemic health impacted = antibiotics
permanent restoration
- A 35-year-old patient presents complaining of mobility of tooth 34, which he feels is becoming worse. On examination, tooth 34 demonstrates Grade II mobility. There is no attachment loss but there is evidence of moderate toothwear affecting a number of teeth, likely attributable to attrition. Radiographic examination reveals generalised widening of the periodontal ligament space of tooth 34 and the tooth responds positively to sensibility testing
i) What is the most likely diagnosis? (1 mark)
Occlusal trauma
ii) Describe how would you manage this patient?
(3 marks)
occlusal adjustment
temporary splinting for stabilising
overnight splint
OH instructions -> control of plaque induced inflammation
orthodontics
- A 60-year-old patient presents complaining of generalised bleeding gums. There are CPITN scores of 4 in each sextant, with 78% sites showing bleeding on probing. A panoramic radiograph shows generalised horizontal bone loss, with 50% alveolar bone loss at the worst sites. The medical history is clear and the dentition is only lightly restored.
i) What is the most likely diagnosis from the above list?
(1 mark)
generalised periodontitis
ii) Which Stage AND Grade would you attribute to this case?
(1 mark)
stage III grade B
iii) What is the single most important factor to determine from the social history?
(1 mark)
whether the patient is the smoker or not
iv) What further investigations would you carry out? (2 marks)
full mouth 6ppc
radiographic assessment
risk assessment
- A patient presents complaining of a constant throbbing pain from the right side of her mandible. This has kept her awake at night. On examination, you establish that tooth 46 is grossly carious and is tender to percussion.
i) What is the most likely diagnosis from the above list?
(1 mark)
periapical periodontitis
irreversible pulpitis ??
ii) What further investigations might you perform?
(2 marks)
electric pulp test to see if it’s reversible or irreversible
periapical radiograph
iii) What are the best treatment options for relief of the patient’s pain? (2 marks)
depending on radiograph, RCT??
XLA
antibiotics if systemic
pain relief
A patient has attended complaining of pain related to tooth 14. Following a complete history and clinical examination you have made a diagnosis of irreversible pulpitis. Having explained the diagnosis to the patient you have obtained consent to perform root canal treatment.
- What number of canals are found, most often, in an upper first premolar?
(1 mark)
two canals
- During instrumentation of the canal where is considered the ideal end point of shaping/obturation?
(2 marks)
the apex //
apical 3rd at least 2 mm away from apex
(the narrowest part of the root canal near the root apex)
- What is the term for maintaining communication between the pulpal space and peri-radicular tissues?
(1 mark)
apical foramen
You have satisfactorily anaesthetised and isolated the tooth. After accessing the pulp chamber of tooth 14, you aim to identify the working length of the canals identified.
- What is a working length in endodontics?
(2 marks)
distance from reference point on tooth surface e.g. buccal cusp
to the point at which the root canal preparation and obturation should terminate, typically at root apex.
- What TWO common intra-operative radiographs can be utilized during endodontic treatment to aid working length determination?
(2 marks)
periapical radiograph
working length radiograph - pa with endo file inserted to estimate working length
- Please state 2 potential causes of a corrected working length changing during the course of endodontic shaping? (2 marks)
apical transportation =
file deviation during prep causes new opening or widening at the root apex
instrument fracture
- Post-core crown:
a. Name 3 materials used for crowns
porcelain
metal
pfm = porcelain fused to metal
b. What is the purpose of a post?
when there is a lot of crown lost = additional retention
support = helps to redistribute chewing forces
reinforcement = RCT teeth are more sucseptible to fracture due to pulp removal and loss of moisture and nutrients
c. Name 3 types of post which can be used?
pre-fabricated posts
custom-cast metal posts
fibre posts
zirconia posts
composite resin posts
d. What name is given to the residual collar of dentine required before placing a post?
ferrule dentine
e. How much gutta percha should be left in the canal space when placing a post?
3-5 mm
f. What is the key purpose of post placement?
provide addition support and retention
g. Describe the width of taper required for the type of crown given in the above clinical photograph. (MCC)
6 to 10 degrees
a. How to decide whether you place conventional vs P&C crown?
amount of tooth structure
location = aesthetics
functional = occlusal forces and bite relationship
patient preference and financial considerations
b. post is too wide : problems?
insufficient retention
root perforation
weakening of tooth structure
compromised seal
difficulty in cementation
c. post is too narrow : problems?
Crown Prep (Incisor)
a. Labial:
a.i. Margin design & reduction? (2)
a.ii. Benefits of that margin design (2)
b. Palatal
b.i. Margin design & reduction? (2)
b.ii. Benefits of that margin design (2)
labial = a chamfer margin with a reduction of about 0.5 to 1 mm
palatal = a shoulder margin with a reduction of about 1 to 1.5 mm
The chamfer margin provides a SMOOTH TRANSITION from the prepared tooth to the restoration, which facilitates accurate impression-taking and ensures a well-fitting crown.
CONSERVATIVE REDUCTION helps preserve more tooth structure, leading to better long-term prognosis and aesthetics.
The shoulder margin provides a CLEAR MARGIN between the prepared tooth and the restoration, aiding in the fabrication process and ensuring a precise fit.
The slightly greater reduction compared to the labial aspect allows for ADEQUATE SPACE for material thickness, improving the STRENGTH and longevity of the restoration.
c. 4 properties of impression material suitable for crown prep.
silicone PVS impression = elastomeric material
- dimensional stability = capture the structures well = setting shrinkage, thermal expansion, storage
- Quality of surface interaction between material & tooth/soft tissue surfaces:
Viscosity - must flow easily
Surface wetting - close contact with teeth/mucosa
Contact angle - how well material envelops the hard/soft tissue surface = record fine details - Accuracy
surface reproduction (ISO)
visco-elasticity / elastic recovery - Dealing with removal and undercuts
Flow under pressure (”shark fin” test)
Rigidity
tear strength = adequate tear strength to withstand removal from undercuts
flowability = should flow easily
biocompability = non-toxic and non-irritating
Full denture
a. Custom tray 3mm spaced: What impression material and why?
b. Why not silicone?
a) heavy-body polyvinyl siloxane (PVS)
helps to accurately capture details pf the edentulous ridge and surrounding tissues
also has high viscosity
_____________
alginate - easy to use, cost-effective, acceptable accuracy, quick setting time, patient comfort
b) ilicone materials, especially light-body types, may not adequately flow into the space between the custom tray and the tissues, resulting in incomplete impression capture. Additionally, silicone materials may lack the necessary viscosity to maintain dimensional stability and prevent distortion during removal from the mouth, which can compromise the accuracy of the final denture fit.
c. 2 areas of primary support on maxilla arch
palatal vault - behind anteriors and extending towards soft palate
posterior palatal seal - slightly beyond the vibrating line
d.i. 1 area of primary support on mandibular arch
d.ii. What muscle lies adjacent to this?
d.i. residual ridge
d.ii. mylohyoid muscle
e. What part of mandible might interfere with maxillary impression within
tuberosity regions during lateral excursion while taking a functional impression?
maxillary tuberosity distally to maxillary molars
internal surface of the mandibular ramus, particularly the area near the mandibular coronoid process
happens during lateral movements such as chewing and speaking
a) another name for master impressions (1 mark)
2nd impressions
b) 2 factors that affect physical retention full dentures (2marks)
fit (base shape) = require full coverage of the denture bearing area
post dam seal
and adaptation to oral tissues such as mucosa
use of undercuts
muscle function and oral anatomy = relation to edentulous ridge, tongue and oral muscles
c) 2 anatomical features for position of posterior border of upper denture (2 marks)
palatal vault
hamular notches
d) 3 anatomical features to include on mandibular ( 3 marks)
residual ridge
mylohyoid ridge
mental foramen
e) 2 materials can use for masters on lowers (2 marks)
Polyvinyl Siloxane (PVS) Impression Material
Zinc Oxide Eugenol (ZOE) Impression Paste
g.) Part of mandible that interferes during maxillary working impression (1 mark)
retromolar pad
how to attain stability in full dentures (2 marks)
ensure proper fitting
consider adhesive use
endo -
a) non setting calcium hydroxide - why is it an ideal inter appointment
medicament (2 marks)
biocompatible
antibacterial properties
b) reasons for obturating (3 marks)
to seal the canal
prevent the passage of microorganisms and fluid along the root canal and to fill the whole canal system to prevent the bacterial recontamination
support and reinforcement = prevents fracture of the tooth by restoring strength and integrity
c) components of GP other than rubber (2 marks)
zinc oxide
radiopacifiers
metallic salts
d) reasons for sealer when using cold lateral compaction (3 marks)
sealing microscopic gaps
enhancing fluid tight seal
cementation and stability
bleaching - a) percentage affected by sensitivity ( 1mark)
60%
b) 3 predisposing factors likely to cause sensitivity (3 marks)
pre-existing sensitivity
high conc of bleaching agent
frequency of change
method
gingival recession
c) external cervical resorption method of action ( 2marks)
demineralisation
inflammatory response
d) root resorption causes ( 2marks)
ortho
trauma
pulpitis / periapical lesions
idiopathic
e) how to prevent root resorption (2 marks)
regular checkups and xray
ortho monitoring
maintain good OH
avoid pressure - bruxism
EDP# and exposed RCT
List 5 functions of a provisional crown in this scenario (5 marks)
To improve aesthetics and provide the patient with realistic expectations
To improve functions of mastication and speech
To resolve gingival inflammation and provide adequate gingival health prior to fitting the definitive
restoration? – to achieve a satisfactory emergence profile for the definitive restoration
To improve occlusion
To act as a marker for the dentist for tooth preparation and errors
Prevents sensitivity
Preserves tooth vitality
Used as isolation for RCT
b) Name 3 types of prefabricated crowns (3 marks)
Polycarbonate Crowns
Clear plastic
?Metal – (aluminium/stainless steel)
c) List 2 disadvantage of a prefabricated crown (2 marks)
inaccuracy - less precise fit
limited aesthetics options
large bank of crowns needed to fit different sizes and shapes
poor marginal integrity