BDS4 Past Papers Flashcards
Name the three components of an RPI system?
- mesial rest
- I-bar clasp
- proximal guide plate
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:
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
State two reasons for choosing to use a lingual bar in a lower RPD design:
- 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
What material is a lingual bar typically made from?
CoCr (cobalt chromium)
Give two fixed restorative treatment options a patient may wish to consider as an alternative to RPD?
- implants
- bridges
What three criteria must be fulfilled before obturation can take place on an endodontically treated tooth?
- continuously tapering funnel shape
- maintain apical foramen in original position
- keep apical opening as small as possible
You decide to use cold lateral compaction with gutta-percha. Give three constituents of gutta-percha cones, in addition to gutta-percha:
- zinc oxide (65%)
- radiopacifiers (10%)
- plasticisers (5%)
What is the function of a sealer when used with gutta percha cones?
Helps to prevent voids within the root canal system
Give three generic sealers that are used in root canal treatment?
- Glass Ionomer
- Zinc oxide eugenol sealers
- Resin based sealers
A patient requests implants, but which two alternative treatment options might you also advise?
- bridges
- RPD
What is the incidence of (i) temporary and (ii) permanent loss of sensation following wisdom teeth removal?
(i) 10-20%
(ii) <1%
Aside from nerve damage, list four further post-operative complications of removing wisdom teeth:
- dry socket
- pain
- bruising
- swelling
- trismus/limited mouth opening
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?
- size of exposure (>1mm pulpotomy)
- time since exposure (pulp cap within 24hr window)
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.
- 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
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:
- 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
The pulp has remained vital after a pulpotomy, what favourable signs would you expect to see on the radiograph?
- continued root lengthening
- continued dentine formation along canal
What is stage 1 of oral transport?
- 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
What is stage 2 of oral transport?
- mastication of food to break it down & mix it with saliva (via molars & premolars)
- soft foods squashed against hard palate via tongue
Name two biological factors that can affect masticatory performance of a human being:
- dental occlusion
- number & condition of teeth
What is meant by the term ‘shortened dental arch’?
- most posterior teeth (molars usually) are missing
- satisfactory oral function with remaining teeth
- 3-5 occlusal units remaining
- at least 20 teeth remaining
Identify three aspects of oral function that are regarded by proponents of the shortened dental arch as acceptable in older patients:
- SDA provides sufficient occlusal stability
- SDA provides satisfactory comfort & appearance
- SDA provides sufficient masticatory function
- Speech is okay
To which group of chemicals does chlorhexidine digluconate belong?
Bisbiguanide antiseptic
Describe the mechanism of action of chlorhexidine digluconate:
- disruption of cell membrane
- interference with protein synthesis
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 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
Give four indications for the use of chlorhexidine mouthwash?
- oral ulceration
- gingivitis/periodontal care
- recurrent pericoronitis of 8s
- post OS
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
What are Non-γ2 amalgams sometimes known as?
High copper amalgams
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
Originally, why was it necessary for manufacturers to add zinc to
amalgam alloy?
- improved handling characteristics
- control of expansion during setting
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)
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
State three sequelae of dental trauma that may influence your treatment
planning for a tooth:
- pulpal necrosis
- external root resorption
- pulp canal obliteration
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
The illustration is of an upper edentulous ridge. Please identify the anatomical landmarks indicated.
(a) incisive papilla
(b) tuberosity
(c) fovea palatinae
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
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
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
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)
What vital signs should you monitor and record before, during and after
sedation?
- HR pulse
- BP
- Blood oxygen levels
In the event of over sedation, which drug should you use to reverse this patient?
Flumazenil
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
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
What is the criteria for consent to be considered valid?
Consent must be:
- voluntary
- informed
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
How much space between teeth is required for implant placement?
7mm
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
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
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
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
What material might be used to treat these abrasion cavities & why?
RMGIC
- due to poor moisture control at the cervical region, composite unsuitable
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
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
What information is needed from a patient for the technician to make a bridge?
- proposed bridge design
- master impression
- bite registration
- shade of teeth
What patient factors can affect the periodontal prognosis of teeth?
- smoking
- systemic disease = diabetes, immunosuppression, pregnancy
- drug history
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
What are some causes of acutely loose fitting dentures?
- weight loss
- poor muscle control due to parkinsons
- ridge resorption after tooth extraction
- tumour growth
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
What skeletal classes are contraindicated for SDA and why?
Severe class II or III
- lack of sufficient occlusal contact between teeth
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
Give some contraindications for a SDA:
- Active periodontal disease
- Poor prognosis of remaining teeth
- Pre-existing TMD
- Any signs of pathological tooth wear
