BDS4 Past Papers Flashcards
(152 cards)
1
Q
Name the three components of an RPI system?
A
- mesial rest
- I-bar clasp
- proximal guide plate
2
Q
The RPI system is designed to allow vertical rotation of a distal-extension saddle into the denture-bearing mucosa without damaging the periodontium of the abutment tooth. Briefly describe how this is achieved:
A
Mesial rest = situated mesially to provide support to saddle without allowing tipping/tilting of abutment tooth
I-bar clasp = When vertical forces are applied during mastication or functional movements, the I-bar transfers these forces to the denture base, preventing excessive stress on the abutment tooth
Proximal guide plate = serves as a minor connector to transmit forces to the major connector to relieve stress from abutment periodontium
3
Q
State two reasons for choosing to use a lingual bar in a lower RPD design:
A
- adequate space available (8mm)
- more comfortable for pt due to less mucosal coverage
- better for OH purposes as doesn’t cover lingual of lower incisors
3
Q
What material is a lingual bar typically made from?
A
CoCr (cobalt chromium)
4
Q
Give two fixed restorative treatment options a patient may wish to consider as an alternative to RPD?
A
- implants
- bridges
5
Q
What three criteria must be fulfilled before obturation can take place on an endodontically treated tooth?
A
- continuously tapering funnel shape
- maintain apical foramen in original position
- keep apical opening as small as possible
6
Q
You decide to use cold lateral compaction with gutta-percha. Give three constituents of gutta-percha cones, in addition to gutta-percha:
A
- zinc oxide (65%)
- radiopacifiers (10%)
- plasticisers (5%)
7
Q
What is the function of a sealer when used with gutta percha cones?
A
Helps to prevent voids within the root canal system
8
Q
Give three generic sealers that are used in root canal treatment?
A
- Glass Ionomer
- Zinc oxide eugenol sealers
- Resin based sealers
9
Q
A patient requests implants, but which two alternative treatment options might you also advise?
A
- bridges
- RPD
10
Q
What is the incidence of (i) temporary and (ii) permanent loss of sensation following wisdom teeth removal?
A
(i) 10-20%
(ii) <1%
11
Q
Aside from nerve damage, list four further post-operative complications of removing wisdom teeth:
A
- dry socket
- pain
- bruising
- swelling
- trismus/limited mouth opening
12
Q
What two things do you need to know about an enamel-dentine-pulp injury before you can decide on whether or not a direct pulp cap or a pulpotomy is the most appropriate treatment?
A
- size of exposure (>1mm pulpotomy)
- time since exposure (pulp cap within 24hr window)
13
Q
You have decided to provide a pulp cap for tooth 11. You have anaesthetised the patient who is now comfortable- explain the stages of the procedure you now carry out.
A
- trauma sticker & radiographic assessment
- LA & rubber dam
- clean area with water & disinfect with sodium hypochlorite 2.5%
- apply calcium hydroxide (dycal) or MTA white to pulp exposure
- restore tooth with composite & review
14
Q
You have decided to provide a pulpotomy for tooth 11. You have anaesthetised the patient who is now comfortable - explain the stages of the procedure you now carry out:
A
- trauma sticker & radiographic assessment
- LA & rubber dam
- clean with saline then disinfect with sodium hypochlorite 2.5%
- remove 2mm of pulp with highspeed round diamond bur
- place saline soaked CW pellet over exposure until haemostasis achieved (if unable remove all coronal pulp)
- apply CaOH then GI then restore with composite
15
Q
The pulp has remained vital after a pulpotomy, what favourable signs would you expect to see on the radiograph?
A
- continued root lengthening
- continued dentine formation along canal
16
Q
What is stage 1 of oral transport?
A
- moving food material from front of mouth/oral cavity to level of posterior teeth
- tongue retracts to pull material posteriorly (pull-back process)
- retraction of hyoid bone & narrowing of oropharynx
17
Q
What is stage 2 of oral transport?
A
- mastication of food to break it down & mix it with saliva (via molars & premolars)
- soft foods squashed against hard palate via tongue
18
Q
Name two biological factors that can affect masticatory performance of a human being:
A
- dental occlusion
- number & condition of teeth
19
Q
What is meant by the term ‘shortened dental arch’?
A
- most posterior teeth (molars usually) are missing
- satisfactory oral function with remaining teeth
- 3-5 occlusal units remaining
- at least 20 teeth remaining
20
Q
Identify three aspects of oral function that are regarded by proponents of the shortened dental arch as acceptable in older patients:
A
- SDA provides sufficient occlusal stability
- SDA provides satisfactory comfort & appearance
- SDA provides sufficient masticatory function
- Speech is okay
21
Q
To which group of chemicals does chlorhexidine digluconate belong?
A
Bisbiguanide antiseptic
22
Q
Describe the mechanism of action of chlorhexidine digluconate:
A
- disruption of cell membrane
- interference with protein synthesis
23
Q
The activity of an oral antiseptic depends on its substantivity. How is substantivity defined and provide two examples of factors that may influence the substantivity of chlorhexidine in the oral cavity?
A
Substantivity = ability of antiseptic to persist and remain active in oral cavity over period of time after initial application
- chlorhexidine adheres to oral surfaces (teeth etc) and spends longer in cavity
- chlorhexidine can form oral reservoirs and slowly release antiseptic over time
24
Give four indications for the use of chlorhexidine mouthwash?
- oral ulceration
- gingivitis/periodontal care
- recurrent pericoronitis of 8s
- post OS
25
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.
- ledging (in curved canals the hand files may catch on curved areas causing ledging)
- perforation (hand instruments can only bend so far, therefor they may penetrate through the canal wall)
- inadequate cleaning and shaping
- broken instruments
26
What are Non-γ2 amalgams sometimes known as?
High copper amalgams
27
Give two advantages, in terms of performance, of a non-γ2 amalgam:
High copper content leads to:
- increased strength (more durable)
- minimised corrosion (less susceptible) which reduces chance of marginal breakdown
28
Originally, why was it necessary for manufacturers to add zinc to
amalgam alloy?
- improved handling characteristics
- control of expansion during setting
29
What effect could occur in a freshly placed amalgam restoration as a
result of the presence of zinc in the amalgam alloy?
Explain the mechanism of this effect.
What is the main symptom that the patient could experience should
this occur?
Expansion of amalgam
- interaction of Zinc with saliva/blood
- bubbles of H2 formed within amalgam
- pressure build up causes expansion
Patient could experience pain (due to pressure on pulp)
30
A 33-year-old patient presents with a discoloured upper left central incisor tooth.
The patient has 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. There are no symptoms, and the patient is concerned with the
appearance. He recalls a blow to the tooth when playing sport a few years
previously.
Indicate how you might determine the aetiology of the discolouration.
- look at the colour of the tooth
- radiographic examination
- vitality testing (ethyl chloride or EPT)
- percussion of tooth
- history
31
State three sequelae of dental trauma that may influence your treatment
planning for a tooth:
- pulpal necrosis
- external root resorption
- pulp canal obliteration
32
A pt attends your clinic with a fractured off MCC, the dentine core has fractured off inside the crown.
What four features of the remaining tooth tissue of the central incisor might indicate whether it can be successfully restored or not?
- Extent of remaining tooth structure (ferrule present)
- Periodontal health and stability (bone levels)
- Vitality and apical health of tooth
- Presence of caries or decay
33
The illustration is of an upper edentulous ridge. Please identify the anatomical landmarks indicated.
(a) incisive papilla
(b) tuberosity
(c) fovea palatinae
34
In terms of complete dentures what is meant by the following terms;
(a) stability
(b) retention
(a) resistance of denture to occlusally directed load
(b) resistance of denture to vertical displacement away from underlying tissues
35
How do you achieve adequate retention in a conventional complete upper denture?
- adequate border extension and peripheral seal (should be 2mm in front of fovea palatinae)
- adequate extension into soft tissue undercuts
- adequate palatal mucosal coverage to allow for adhesion/cohesion with saliva
36
Why is written consent required in advance of the treatment day in sedation dentistry?
Gives the patient time to think about their decision between appts
37
What drug would a UK-trained dentist select to sedate a patient via IV route? what preparation of this drug would be used?
IV Midazolam (5mg/5ml ... start with 1mg)
38
What vital signs should you monitor and record before, during and after
sedation?
- HR pulse
- BP
- Blood oxygen levels
39
In the event of over sedation, which drug should you use to reverse this patient?
Flumazenil
40
List three instructions that the patient should follow post sedation for a minimum of 12 hours after he is discharged from your care:
- rest & avoid strenuous activities
- avoid alcohol
- avoid sedatives
41
Your patient has sustained a displaced fracture of the right body of the mandible.
Other than pain, bruising and swelling, name six clinical signs or symptoms
commonly described in such an injury.
- malocclusion
- restricted jaw movement/trismus
- crepitus
- excess mobility of multiple teeth
- numbness or altered sensation of lower lip, chin or teeth
- visible deformity of mandible
42
What is the criteria for consent to be considered valid?
Consent must be:
- voluntary
- informed
43
Name 6 things that you should tell a patient about treatment in order to gain valid consent?
- options for treatment,
- the risks & potential benefits associated with treatment
- the likely prognosis
- cost of the treatment proposed
- consequences of not having treatment
- your recommended option
44
How much space between teeth is required for implant placement?
7mm
45
Discuss the different BEWE scores:
0 = no erosive weather
1 = initial loss of surface
2 = distinct defect hard tissue loss <50% of surface
3 = hard tissue loss >/= 50% of the surface area
Add up scores for all sextants and then risk assess
- None <2
- Low = 3-8
- Medium = 9-13
- High = >14
46
Give examples of desensitising treatment that can be used for patients experiencing treatment:
- duraphat fluoride varnish
- prime & bond over exposure surfaces
- desensitising agents
- sensodyne toothpaste applied topically
47
You are considering using the Dahl technique to treat a toothwear patient. Give examples of contraindications for use of this technique:
- Pts with active periodontal disease
- Pts with TMD
- Pts taking bisphosphonates
48
Name 4 constituents of composite resins and give an example for each:
- Resin =Bis-GMA
- Glass = Silica or quartz
- Low weight dimethacrylate = TEGDMA
- Light activator = camphorquinone
- Silane coupling agent
49
What material might be used to treat these abrasion cavities & why?
RMGIC
- due to poor moisture control at the cervical region, composite unsuitable
50
How do you determine success of PMPR/perio treatment?
BSP =
- pocket depths <4mm
- plaque scores <15%
- bleeding scores <10%
* not achieveable for all patients so pts with significantly improved OH, reduced BoP & reduction of probing depths
51
A patient is deemed to be suitable for regenerative periodontal surgery. What are the indications for this?
- 2 and 3 wall defects
- grade 2 furcations in mandibular teeth
- grade 2 buccal furcation in maxillary molars
52
What information is needed from a patient for the technician to make a bridge?
- proposed bridge design
- master impression
- bite registration
- shade of teeth
53
What patient factors can affect the periodontal prognosis of teeth?
- smoking
- systemic disease = diabetes, immunosuppression, pregnancy
- drug history
54
What are some causes of denture stomatitis?
- Immunosuppression (diabetes, HIV)
- Poor dental hygiene
- Poor denture hygiene (wearing dentures overnight)
- Xerostomia
- Broad spectrum antibiotic use
- Systemic steroid use
55
What are some causes of acutely loose fitting dentures?
- weight loss
- poor muscle control due to parkinsons
- ridge resorption after tooth extraction
- tumour growth
56
What 2 topical agents can be used for treatment of denture induced stomatitis?
- Miconazole oromucosal gel 50mg/g
- Nystatin oral suspension 100,00 units/ml
57
What skeletal classes are contraindicated for SDA and why?
Severe class II or III
- lack of sufficient occlusal contact between teeth
58
Periodontal disease is a contraindication in SDA, why?
- drifting of periodontally compromised teeth under occlusal load (distal migration due to increase in anterior load)
- loss of alveolar bone leading to compromised denture bearing area in long term
59
Give some contraindications for a SDA:
- Active periodontal disease
- Poor prognosis of remaining teeth
- Pre-existing TMD
- Any signs of pathological tooth wear
60
Why are sub-alveolar fractures of teeth considered poor prognosis?
- lack of coronal tissue to bond to
- poor moisture control
- difficulty cleaning
- inability to take impression for indirect rest
- difficult to establish marginal integrity
61
What faults can occur to cause de-bonding of bridge?
- poor moisture control during cementation
- poor prep of tooth
- unfavourable occlusion
- parafunctional habits
- trauma to face/area
- poor OH
62
What are the different types of toothwear?
- Attrition
- Abrasion
- Erosion
- Abfraction
63
Name three methods of desensitising teeth?
- Duraphat fluoride varnish application
- Dentine desensitising agents or prime and bond
- sensodyne relief toothpaste
64
What is the DAHL technique?
Method of gaining space in localised toothwear
- appliance is placed on anterior teeth to cause posterior disclusion and increase OVD by 2-3mm
- over a period of 3-6 months posterior teeth erupt into propped open occlusion
- creates space anteriorly for TW restoration without further tooth reduction
65
List four contraindicated groups for use of the DAHL technique?
Patients:
- with active periodontal disease
- TMJ disorders
- post orthodontic tx
- taking bisphosphonates
- with dental implants
66
Why is RMGIC not good as a luting cement?
Contains HEMA, which absorbs water causing swelling of materials AND it is cytotoxic to pulp
67
In a periodontal chart, what results would show teeth with worst prognosis?
- Loss of attachment scores
- Mobility scores
- Furcation involvement
68
Explain "ingestion" in relation to oral transport:
- Movement of food from external environment into the mouth accomplished by biting where the lips provide anterior oral seal
- Orbicularis oris & buccinator help to control food bolus & prevent spillage
69
Explain "stage 1 transport" in relation to oral transport:
- moving material from front of mouth to level of posterior teeth
- food gathered on tongue tip, tongue retracts & pulls material to posterior teeth
- associated with retraction of hyoid bone & narrowing of oropharynx
70
Explain "mechanical processing" in relation to oral transport:
- solid food broken and mixed with saliva before swallowing
- bolus squashed by tongue against hard palate
- food chewed with premolars / molars
71
Explain "stage II transport" in relation to oral transport:
- bolus moved anterior to posterior via squeeze back mechanism by tongue & hard palate
- tip of tongue touches behind upper incisors on palate and squeezes back
- solids moved through fauces to pharyngeal surface of tongue
- posterior oral seal holds liquids at pillars of fauces
72
Explain "swallowing" in relation to oral transport:
- involuntary movements push bolus through pharynx to oesophagus
- UOS opens then epiglottis closes to prevent backflow
- peristalsis occurs to move bolus towards stomach
73
What biological factors affect masticatory performance of humans?
- sufficient dentition
- sufficient oral saliva
74
What is the shortened dental arch?
Most posterior teeth missing but still satisfactory oral function without replacement due to occluding anterior teeth
- need 3-5 occlusal units remaining
- priority of maintaining anterior & premolar dentition
75
To which group of chemicals does chlorhexidine digluconate belong?
Bisbiguanide antiseptic
76
Explain the mode of action of chlorhexidine:
Dicationic
- 1 cation adheres to pellicle
- 1 cation disrupts bacterial membrane
- works against gram +ve & -ve bacteria, fungi, viruses and candida
77
What is the substantivity of chlorhexidine digluconate?
12 hours
78
The activity of an oral antiseptic depends on its substantivity. How is substantivity defined and provide two examples of factors that may influence the substantivity of chlorhexidine in the oral cavity?
Substantivity = ability of antiseptic to persist and maintain antimicrobial activity in oral cavity
1. consumption of food and drinks straight after chlorhexidine use can remove it from oral surfaces
2. saliva composition and flow rate (high flow rate will dilute chlorhexidine)
79
Give four indications for the use of chlorhexidine MW?
- mucosal ulceration
- pericoronitis (used to irrigate/relieve symptoms)
- periodontal abscess
- candidal infection
80
What is the physiology of postural hypotension?
- blood pools in legs
- poor venous return
- reduced HR
81
What is the mechanism of action of an RPI system?
Stress relieving clasp system:
- distal proximal plate and I bar clasp disengage during function
- allows for vertical rotation of distal saddle WITHOUT distoaxial torque of last standing tooth
- distal proximal plate and mesial rest prevent tilting
82
A patient presents with loose & old denture that appear to be causing denture induced stomatitis.
What are the causes of denture stomatitis?
- Immunosuppression [diabetes, HIV]
- Poor denture hygiene
- Xerostomia
- Broad spectrum antibiotic use
- High carbohydrate diet
- Systemic steroid use
83
What microbes are involves in denture-induced stomatitis?
- Candida Albicans
- Staph Aureus
84
What would initial tx be for a patient with denture induced stomatitis?
- Denture hygiene instruction
- 0.2% CHX, use 2x per day for 1 min
- Smoking cessation advice
- Topical Miconazole 20mg/g 4x daily (send 80g tube)
- Fluconazole 50mg, 1x daily, 7 days
85
Give 2 topical agents that can be used to treat denture stomatitis:
Miconazole 20mg/g (send 80g tube), apply pea sized amount 4x daily
Nystatin 100,000units/ml (send 30 ml, 1ml after food 4x daily for 7 days)
86
What differences can there be between old and new dentures?
- FWS changes (OVD alterations)
- path of insertion changed
- different flange extension
- palatal extension different
- tooth shade/shape/size
87
A patient presents unable to tolerate new dentures having worn the old ones for 20 years, they have become loose over the past 18 months & this is why they were replaced.
What method could be used to make dentures he can tolerate?
Replica denture technique
88
A patient presents unable to tolerate new dentures having worn the old ones for 20 years, they have become loose over the past 18 months & this is why they were replaced.
What 2 methods can dentists use to improve fit of loose dentures?
- Reline
- Rebase
[remake]
89
Identify anatomical features that may make production of a maxillary denture difficult?
- High arched palate
- Tori palatinus
90
Give 5 things that should be checked at the denture try in stage:
- Retention & Stability
- Extensions
- Occlusion [rvd, ovd, fws]
- Speech
- Appearance
91
How many occlusal units are there if a patient has: 1 pair of occluding premolars and 1 pair of occluding molars?
3 units
92
In which skeletal classes is SDA contraindicated?
Severe class II or III malocclusions
93
What can be used to sandblast an adhesive bridge in dentistry during fabrication?
Aluminium Oxide (removes 50 microns)
94
What type of bridges can you get anteriorly?
- Adhesive cantilever bridges (resin bonded bridge)
- Fixed-fixed conventional bridge
- Conventional spring cantilever bridge
95
What are some reasons for debonding of a bridge clinically?
- poor moisture control during cementation
- unfavourable occlusion/heavy contacts
- parafunctional habits
- trauma
- poor abutment health
- over tapered prep
- poor OH
96
Give 4 methods of checking if a bridge has debonded clinically?
- Assess with probe around abutments/wings
- Look visually
- Assess mobility of bridge
- Floss around bridge
97
You decide that a patient would benefit from implant placement. Give 2 general and 2 local things the dentist must check:
General = smoking status, medical history
Local = bone quantity, suitable space for implant placement
98
Why do we obturate teeth after removing the pulp?
- prevent passage of microorganisms
- prevent re-infection
- block apical foramen
- provide apical & coronal seal
99
Give 4 methods of obturation?
- Cold lateral compaction
- Warm vertical compaction
- Continuous wave compaction
- Carrier based obturation
100
Name 3 post materials:
- Fibre (carbon/glass fibre)
- Cast metal (SS, Type IV gold)
- Ceramic (zirconia)
101
Name 3 core materials:
- Composite
- Amalgam
- GI
102
Explain the meaning of Ingestion:
- movement of food from external environment into mouth
- accomplished by biting
- lips form anterior oral seal
- orbicularis oris and buccinator help control bolus & prevent spillage
103
Explain the meaning of Stage 1 oral transport:
- Material is moved from front of mouth to level of posterior teeth
- Food gathered on tongue tip, tongue retracts, material pulled to gather on posterior teeth, hyoid retracts, narrowing of oropharynx
104
Explain the meaning of Mechanical processing (in reference to feeding sequence):
- solid food broken down & mixed with saliva before swallowing
- bolus squashed against hard palate
- food chewed with premolars and molars
105
Explain the meaning of Stage 2 oral transport:
- Bolus moved posteriorly via squeeze back method
- Posterior oral seal holds liquids at level of pillars of fauces
106
Explain the meaning of Swallowing:
- Involuntary movements push bolus through pharynx to oesophagus
107
A patient has an upper complete denture, on the lower arch only the anterior teeth remain.
What would happen to the upper arch if the lower arch was not provided with a lower denture?
- Flabby ridge development
- Forces directed in anterior region, causing displacement of anterior portion of upper denture
- Results in excessive & rapid bone loss of maxillary anterior ridge & replaced by excess fibrous tissue
108
How is combination syndrome and upper flabby ridge development managed?
Take a mucostatic impression so that tissues are recorded at rest
- cut window in impression tray and use a low viscosity silicone material
- ensures that the flabby ridge is not compressed
109
What are the components of composite?
- Resin = BIS-GMA
- Glass = silica or quartz
- Low weight dimethacrylate = TEGDMA
- Photoinitiator = camphorquinone
- Silane coupling agent
110
What factors can influence localised mobility?
- width & height of PDL
- presence of inflammation
- number/length of roots
- amount of bone
111
A patient attends with Paget's disease, their denture no longer fits properly.
Explain the anatomical changes, pathology and incidence behind the reason why the denture no longer fits.
- Pagets causes increased bone turnover leading to enlarged and weakened bones.
- This would cause the denture to no longer fit.
- Usually affects M>W
112
How do dental extractions affect a patient with Pagets disease?
- Increased bleeding risk
- Increased risk of jaw fracture
- Delayed healing & complications
- Risk of infection heightened due to altered wound healing
113
You decide that a patient with Paget's disease requires a dental extraction, what precautions would you take?
- CHX daily 1 week pre-op
- CHX (1-2mins) immediately before XLA
- Atraumatic XLA technique
- Closure via primary intention (suturing)
- Closely followed-up
114
You are carrying out root canal on an upper right canine under local
anaesthetic. You are irritating the canal with dilute solution of sodium hypochlorite when the patient suddenly feels intense pain. Within minutes you notice a marked facial swelling in the area and profuse bleeding into the root canal from the periradicular tissues.
What is the most likely cause for these signs and symptoms and why?
Tissue necrosis due to:
- extrusion of sodium hypochlorite through apex into surrounding tissues
- caused by excessive pressure, losing CWL, locking syringe in canal, immature tooth with large apical diameter
115
What would be your immediate action after tissue necrosis due to extrusion of sodium hypochlorite through apex?
- Stop irrigation/procedure immediately & reassure pt
- LA for pain relief
- Copious irrigation with saline to remove NaOCl
- Dress tooth with non-setting CaOH
- Consider specialist referral if concerned (30% increase in swelling compared to contralateral)
- Complete Datix & note incident in pt notes
- Follow up
116
What instructions do you give to patient after tissue necrosis occurs:
- Cold compress for next 2-4 days
- Analgesic advice (400-600mg ibuprofen 4x daily)
- Review pt within 24 hours
- Tell pt to keep an eye on systemic symptoms
117
You previously caused tissue necrosis when performing RCT on a patient. They return 4 weeks later & their condition has resolved and they wish to complete the treatment.
How would you prevent the same incidence from happening again?
- Good pre-op radiograph to assess CWL
- Use saline to test that seal has worked around tooth
- Do not wedge needle into canal
- Use light forces (finger never thumb) when irrigating
- Ensure stopper is 1-2mm short of CWL
- Do not rush procedure
118
What concerns do patients commonly have about the use of amalgam?
- poor aesthetics
- mercury poisoning & toxicity
- metal allergies
- discolouration of teeth & surrounding tissues
- environmental impact
- pregnancy concerns
119
What reassurance can you give patients about the safety of amalgam?
- Risk of mercury toxicity is very low
- It has been used for many years with no evidence based problems
- Amalgam on environment is less problematic than consumption of fish & seafood
- Amalgam is disposed of carefully to minimise effect on environment
120
Describe the different distributions of LA:
Infiltration = deposited around the terminal branches of nerves
Block = deposited beside nerve trunk
121
What is the mechanism of action of LA?
- LA binds to a site in the Na channel & blocks it, preventing Na influx
- Blocks the action potential generation and propagation
- Block persists so long as a sufficient number of Na channels are blocked
122
Patient presents with fractured central incisors, fracture extends to the root surface.
What are the options for tooth replacement?
- Provisonal overdenture
- XLA of teeth & denture
- Post crown
- Vaccum formed splint with replacement teeth
123
What are the clinical signs of erosion?
- Enamel surface affected with loss of surface detail
- Surface becomes flat & smooth
- Dentine becomes exposed & presents as a cupping appearance
- Bilateral, concave lesions without chalky appearance
- Shiny appearance
- Translucency of incisal edges
124
What are the causative factors of toothwear?
Loss of tooth surface by a chemical/mechanical process without involvement of bacteria
125
What are the signs and symptoms of reversible pulpitis?
- Pain to cold (lasting only a few seconds & resolves after stimulus removed)
- No change in blood flow
- No spontaneous pain
- Usually associated with caries, deep restoration or exposure of dentine
126
How is reversible pulpitis managed?
- Removal of causative stimulus
- Eg. remove caries, replace deep restoration & place liner, desensitising agents
- Follow up to ensure symptoms resolve
127
What is symptomatic irreversible pulpitis?
Inflamed pulp that is incapable of healing, still vital
- XLA or pulpotomy/RCT needed
128
What are the characteristics of an ideal post?
- Parallel sided
- Non-threaded
- Cement retained
129
What are the different types of dentine and how do they bond?
Primary Dentine = laid down during development, open tubules, good for bonding
Secondary Dentine = laid down during function/as we age, adequate for bonding
Tertiary Dentine = laid down in response to threatening stimuli, poor bonding ability due to poorly organised tubules or sclerosed tubules
130
What is the setting reaction of amalgam?
Ag3Sn + Hg --> Ag3Sn + Ag2Hg3 + Sn7Hg9
131
What documentation is required by the practise as proof of legitimate disposal of waste and state the minimum period of time that the document should be retained by the practise:
- Waste transfer note
- 2 years
132
What are the advantages of the crown down technique?
- allows for easier straight line access
- removes bulk of infected tissue to allow for reservoid for irrigant
- keeps reference point for WL
133
If using composite resin cement, what material ensures a good bond to porcelain?
Silane coupling agent
- has a bifuncitional molecule
134
What advantages do ProTaper files have over K files?
- shape memory
- super-elasticity
- decrease lateral pressure so decreased risk of ledging
- increased cutting efficiency
135
Give 3 reasons for why a file may separate in a root canal:
- Flexural stress
- Torsional stress
- Lack of straight line access (curved canal)
136
What is the thickness of articulating paper?
20um
137
Give 4 possible faults during denture base production and explain why they occur:
1. Contraction porosity = too much monomer, insufficient pressure, insufficient excess material
2. Gaseous porosity = monomer boiling in bulkier parts of denture
3. Granularity = not enough monomer
4. Crazing = internal stresses due to fast cooling rate
138
What are the stages of crown prep?
- Occlusal reduction
- Separation
- Buccal reduction (prepare in 2 planes)
- Palatal/lingual reduction
- Shoulder or Chamfer finish
- Check occlusal surface & clearance
139
Give 4 advantages of a CoCr denture base:
- Thinner (more lightweight)
- High strength
- High thermal conductivity
- More hygienic due to lower porosity
140
Give 2 disadvantages of a CoCr denture base:
- More expensive & longer lab time
- Difficult to add teeth on in future
141
What undercuts are required for clasps of SS, Au and CoCr?
SS = 0.75mm
Au = 0.5mm
CoCr = 0.25mm
142
What are the constituents of alginate?
- Salt of alginic acid
- Calcium sulphate
- Sodium alginate
- Trisodium phosphate
- Fillers
- Modifiers, flavourings and chemical indicators
143
Give 3 advantages of elastomeric impression materials over alginate:
- Higher tear strength
- Greater elastic recovery
- Increased reproduction of surface detail compared to alginate
144
How is an upper complete denture retained?
- Good neuromuscular control
- Extension into buccal sulcus
- Good peripheral seal
- Adhesion & cohesion
145
Other than remaking, how can you improve retention of dentures?
- Relining
- Rebasing
- Implant retained
- Add precision attachments if dentate
146
How can you check the retention of an upper complete denture clinically?
Pull vertically on anterior teeth to see if denture comes away easily from pt tissues
147
How can you check stability of a denture clinically?
Place fingers on occlusal surface & try rocking denture
148
What is the biometric guidance for setting upper & lower teeth?
- Maxillary teeth placed bucally to ridge
- Mandibular teeth placed over the ridge (reduces tongue restriction)
149
What is a post dam?
Extension of the denture from hamular notch to hamular notch along the vibrating line
- the junction between the hard & soft palate which is compressible tissue
- 1-2mm anteriorly to palatine fovea
150
What should the distal extension of a lower complete denture be?
2/3rds onto retromolar pads
151
What anatomical features help to set the incisors on an upper denture?
- Midline of face/philtrum of lips helps to set centreline
- Canine line should be in line with outer canthus of eye
- Teeth should be positioned 1cm anterior to incisive papilla
