NDAEB - National Dental Assisting Examination Board Clinical Support Procedures 2 — Questions and Answers
Question 1: A dental assistant is preparing alginate for a mandibular full-arch impression. The mixed alginate appears grainy and sets faster than expected. Which error in technique is most likely responsible?
- Too much water was added to the alginate powder
- The water temperature was too warm, accelerating the set (Correct answer)
- The tray was loaded too slowly after mixing
- The powder was measured with a slightly heaping scoop
Correct answer: The water temperature was too warm, accelerating the set
Alginate is highly temperature-sensitive. Warm water accelerates the chemical reaction, shortening working time and producing a grainy, fast-setting mix. Cold water is used to extend working time when needed. Powder/water ratio errors affect consistency but not typically the speed of set in this way.
Question 2: A bitewing radiograph shows overlapping of the posterior interproximal contacts, making it impossible to assess for proximal caries. Which positioning error caused this?
- Excessive positive vertical angulation of the X-ray beam
- Insufficient negative vertical angulation of the X-ray beam
- Incorrect horizontal angulation — the beam was not directed through the contact points (Correct answer)
- The receptor was placed too far anteriorly in the patient's mouth
Correct answer: Incorrect horizontal angulation — the beam was not directed through the contact points
Overlapping of interproximal contacts is caused by incorrect horizontal angulation. The X-ray beam must pass through the contact points at a precise 90-degree angle in the horizontal plane. Vertical angulation errors cause elongation or foreshortening, not overlapping.
Question 3: When placing a rubber dam, the dental assistant notices the dam is beginning to tear at the punched hole around the anchor clamp on tooth 3.6. What is the most appropriate immediate action?
- Reinforce the area with a small piece of dental dam material and continue
- Stop the procedure immediately, remove the dam, and replace it with a new one (Correct answer)
- Apply petroleum jelly around the clamp to reduce tension on the dam
- Proceed carefully and monitor the tear throughout the procedure
Correct answer: Stop the procedure immediately, remove the dam, and replace it with a new one
A torn rubber dam must be replaced immediately. It no longer provides adequate isolation, compromising the sterile field and the quality of the procedure. More critically, fragments of a torn dam can be aspirated or swallowed by the patient, creating a safety hazard.
Question 4: During a posterior composite restoration, the dental assistant is positioning the high-volume evacuator (HVE). Which placement technique provides the best visibility and evacuation efficiency?
- Hold the HVE tip directly above the handpiece, pointed downward into the preparation
- Place the HVE tip parallel to the tooth being treated, approximately 1–2 mm away on the opposite side from the handpiece bevel (Correct answer)
- Position the HVE tip at the corner of the mouth on the opposite side of the arch
- Rest the HVE tip on the occlusal surface of the tooth being prepared
Correct answer: Place the HVE tip parallel to the tooth being treated, approximately 1–2 mm away on the opposite side from the handpiece bevel
The HVE tip should be placed parallel to the long axis of the tooth and approximately 1–2 mm from the site, on the side opposite the handpiece bevel. This position intercepts water and debris at the source, keeps the operative field clear, and avoids obstructing the operator's line of sight.
Question 5: A patient with a known history of asthma begins wheezing and reports chest tightness during a routine appointment. The procedure has been stopped and the patient is sitting upright. What is the dental team's first clinical action?
- Administer oxygen at 6 L/min via nasal cannula
- Call 911 immediately
- Assist the patient in using their own bronchodilator (rescue) inhaler (Correct answer)
- Have the patient breathe slowly into a paper bag to restore COâ‚‚ levels
Correct answer: Assist the patient in using their own bronchodilator (rescue) inhaler
For a conscious asthma patient experiencing bronchospasm, the first action is to assist them in using their own prescribed bronchodilator inhaler, which rapidly relaxes bronchial smooth muscle. Oxygen and emergency services are indicated if the inhaler provides no relief or the patient deteriorates. A paper bag is used for hyperventilation, not bronchospasm.
Question 6: After seating a full-coverage porcelain-fused-to-metal crown, the dentist asks the dental assistant to help evaluate the occlusion. The patient bites on articulating paper and reports the crown feels 'high.' Which instrument should the dental assistant have ready for the dentist to use next?
- A flame-shaped finishing bur in the high-speed handpiece
- A round carbide bur in the slow-speed handpiece
- A fine diamond or finishing bur in the high-speed handpiece to selectively adjust the marked contact (Correct answer)
- A rubber polishing cup with pumice to polish the marked area
Correct answer: A fine diamond or finishing bur in the high-speed handpiece to selectively adjust the marked contact
High spots on ceramic or PFM restorations are adjusted using a fine diamond or finishing bur in the high-speed handpiece on the exact area marked by the articulating paper. This allows precise, selective reduction. A coarse or round bur would remove too much material indiscriminately, and polishing would not reduce occlusal height.
NDAEB - National Dental Assisting Examination Board Clinical Support Procedures 2
A dental assistant is preparing alginate for a mandibular full-arch impression.
The mixed alginate appears grainy and sets faster than expected.
Which error in technique is most likely responsible?