ORE Part 2 Clinical Skills Assessment 2 — Questions and Answers
Question 1: When performing rubber dam isolation for endodontic treatment, which clamp type is most appropriate for a lower first molar?
- Butterfly clamp (W56)
- Wingless clamp such as Ivory 26 or Dentsply Ash 8A (Correct answer)
- Cervical clamp (212)
- No clamp needed, just ligatures
Correct answer: Wingless clamp such as Ivory 26 or Dentsply Ash 8A
Wingless clamps such as the Ivory 26 or Dentsply Ash 8A are designed for molar teeth and provide excellent retention on the lower first molar. The clamp jaws grip below the height of contour of the tooth, and the four-point contact ensures stability during treatment. Butterfly clamps are used for premolars.
Question 2: A patient presents for an OSCE station requiring suturing of a surgical wound. Which suturing technique produces the best wound eversion for intraoral wounds?
- Simple interrupted sutures
- Continuous locking sutures
- Horizontal mattress sutures (Correct answer)
- Subcuticular sutures
Correct answer: Horizontal mattress sutures
Horizontal mattress sutures are excellent for producing wound edge eversion, which promotes healing by primary intention. They distribute tension across a wider area than simple interrupted sutures, reducing the risk of tissue tearing, and are particularly useful for flap closure over extraction sockets.
Question 3: During a clinical skills assessment, what is the correct working length for root canal preparation?
- Exactly at the radiographic apex
- 0.5–1mm short of the radiographic apex
- 2mm beyond the radiographic apex
- At the cemento-dentinal junction, confirmed with an electronic apex locator (Correct answer)
Correct answer: At the cemento-dentinal junction, confirmed with an electronic apex locator
The ideal working length is at the cemento-dentinal junction (CDJ), which is typically 0.5–1mm short of the radiographic apex. Electronic apex locators provide the most accurate determination of the CDJ position. Working beyond this point into the periapical tissues causes unnecessary damage and poor obturation seal.
Question 4: What is the minimum wall thickness of remaining tooth structure recommended before placing a post-retained restoration?
- 0.5mm
- 1mm (Correct answer)
- 2mm
- 3mm
Correct answer: 1mm
A minimum of 1mm of sound dentine should remain circumferentially around a post to reduce the risk of root fracture (the ferrule effect). The ferrule — a 1.5–2mm collar of dentine encircled by the crown margin — provides resistance to rotational and lateral forces and is critical for the long-term success of post-retained restorations.
Question 5: When recording a shade for an anterior composite restoration, at what point during the appointment should shade selection ideally be performed?
- After rubber dam placement
- At the beginning, before the tooth dehydrates (Correct answer)
- After cavity preparation
- Under the operating light at the end of treatment
Correct answer: At the beginning, before the tooth dehydrates
Shade selection should be performed at the beginning of the appointment, before tooth dehydration occurs. Dehydrated teeth appear lighter and more opaque, leading to inaccurate shade matching. The shade tab should be held at the same level as the tooth, in natural daylight or colour-corrected lighting, and the decision made within 5–7 seconds to avoid retinal fatigue.
Question 6: Which rotary file system feature reduces the risk of cyclic fatigue fracture during root canal preparation?
- Increased taper and larger file diameter
- Nickel-titanium alloy with controlled memory (CM wire) (Correct answer)
- Stainless steel composition
- Higher rotational speed
Correct answer: Nickel-titanium alloy with controlled memory (CM wire)
NiTi files made from controlled memory (CM) wire or heat-treated alloys (e.g., Gold, Blue) have significantly improved cyclic fatigue resistance compared to conventional NiTi. The heat treatment changes the crystalline structure, increasing flexibility and the ability to withstand repeated bending cycles in curved canals without fracturing.
ORE Part 2 Clinical Skills Assessment 2
When performing rubber dam isolation for endodontic treatment, which clamp type is most appropriate for a lower first molar?