ADC Practical Exam common mistakes
ADC Practical Exam · Understand the traps and how to avoid them.
Starting a treatment session with the handpiece or instruments already laid out and the unit running before hand hygiene and before patient bib, eyewear and gloves are in place, so the observed sequence is gloves-on-then-arrange.
Candidates rehearse the clinical steps they are graded on but treat set-up as invisible time; under time pressure they touch drawer handles, light switches and the keyboard with gloved hands and then return to the patient, because no one ever taught them a fixed choreography for the first 60 seconds.
What to do instead
Rehearse a scripted opening sequence aloud until it is automatic: hand hygiene, clean barriers and surface wipe, lay out only what the appointment needs, don gloves last, then patient. Practise it in the same order in every mock session so the examiner sees an unbroken chain rather than a scramble.
Removing gloves and then touching the patient record, the radiograph mount, or a drawer without hand hygiene, and reusing a surface barrier that was contaminated earlier in the session.
Gloves feel like a protective layer rather than a contaminated one; candidates think of them as protecting themselves and lose track of the moment they become a transmission route. Fatigue late in a long session also erodes the sequence.
What to do instead
Train a hard rule: gloves come off before any object outside the operatory field is touched, and hand hygiene immediately follows glove removal. Verbally narrate the transition during practice so it becomes a cue rather than a decision.
Preparing a Class II cavity and leaving a proximal box that is not cleared to the contact, or failing to break the contact, then placing a matrix band over an uncleared margin.
Candidates focus on the occlusal outline and caries removal and stop when the cavity 'looks clean' from above; the proximal view is not checked because the operator does not habitually shift position or use a mirror to inspect the box.
What to do instead
Before any matrix placement, deliberately inspect the box from the proximal aspect with a mirror and probe the gingival seat and axial wall. Make breaking the contact an explicit checkpoint you state out loud in practice so it cannot be skipped under time pressure.
Restoring a posterior tooth with a contact that is open or a contour that is flat, then failing to check the occlusion before dismissing the patient.
The matrix is removed and the restoration looks acceptable from above; candidates do not carry floss through the contact or use articulating paper because they are behind schedule and assume the anatomy is adequate.
What to do instead
Build a fixed finishing protocol: floss through every proximal contact, check marginal adaptation with a probe, then mark and adjust in centric and in excursion before the patient leaves the chair. Practise the sequence until it takes under two minutes so time pressure stops being a reason to skip it.
Losing the working length during canal preparation, either by failing to re-measure after coronal flaring or by not confirming patency, then obturating short or long without recognising it.
Candidates take one length measurement at the start and treat it as fixed; they do not account for the reference point changing when the crown is reduced or the rubber dam clamp shifts.
What to do instead
Establish and record a reference point and repeat the length determination after coronal access and flaring is complete, before master cone selection. Confirm the master cone fits to length and is tug-back positive before sealer is mixed.
Using a single straight file in a curved canal with a watch-winding motion and no recapitulation, then continuing to instrument after the file no longer reaches the established length.
Candidates equate effort with progress and keep filing when the file is binding, because stopping to irrigate and recapitulate feels like losing time; they also do not pre-curve the file for the canal curvature.
What to do instead
Adopt a strict rule that any file that will not reach length is removed, the canal irrigated and recapitulated, and a smaller or more curved instrument used. Pre-curve files for curved canals and check the rubber stop against the reference point at every insertion.
Probing with the probe held at a shallow angle and walking it along the tooth without walking the base of the pocket, then recording a chart that does not match the actual attachment loss.
Candidates probe to see whether it bleeds rather than to measure; they also avoid uncomfortable areas and under-record deep pockets because the numbers look alarming and they are unsure what to do next.
What to do instead
Practise probing on a model with the probe parallel to the long axis and the tip walking along the root surface, calling out each site aloud. Record what you measure, not what you expect, and state the site-specific depth and bleeding as you go.
Instrumenting a periodontal site with a curette whose cutting edge is not adapted to the tooth surface, using a vertical stroke and excessive lateral pressure that leaves burnished calculus behind.
Candidates use the instrument they were handed rather than selecting by area and surface; they confuse effort with effectiveness and do not check tactilely whether the surface is smooth after each stroke.
What to do instead
Before starting, identify the area and choose the correct instrument and cutting edge; after each set of strokes, stop and tactilely confirm smoothness with the probe. Use overlapping strokes with light lateral pressure and re-check the surface rather than assuming the deposit is gone.
Taking an impression with the tray not seated fully, or with material that has begun to set, and then pouring and mounting a cast without inspecting the impression for voids and drags.
Candidates are anxious about the patient's gag reflex and rush the seat; they also assume the laboratory will notice defects, so they never inspect the impression critically before it leaves the chair.
What to do instead
Inspect the impression against the prepared teeth before the patient is dismissed, checking margins, voids and tray exposure. If it is defective, repeat it in the same appointment. Practise tray selection and material mixing times so seating is unhurried.
Extracting a tooth with forceps applied high on the crown and a purely buccal force, without a periapical radiograph reviewed beforehand and without checking for root fracture or retained root after removal.
Candidates want the tooth out quickly and skip the pre-operative film review, then do not inspect the socket because the crown came away cleanly and the bleeding stopped.
What to do instead
Review the radiograph before starting and state the root morphology and any proximity to the sinus or nerve aloud. After removal, inspect the tooth for completeness, inspect and gently curette the socket, and confirm haemostasis before dismissing the patient.