MDCN Dental Assessment common mistakes
MDCN Dental Assessment · Understand the traps and how to avoid them.
Reading the entire clinical scenario once and then answering from recall of a similar past case, without extracting the specific values given (age, probing depths, bleeding score, radiograph findings, drug history) into a short list before choosing an option.
Under time pressure candidates pattern-match to a familiar vignette and import assumptions the stem does not support; the exam deliberately varies one or two variables from the classic picture, so the recalled answer is often the distractor.
What to do instead
Adopt a fixed 20-second stem protocol: underline every numeric value and qualifier (uncontrolled diabetic, smoker, on warfarin, pregnant, immunocompromised), restate the actual question in your own words, then eliminate options that are true in general but not true for these values. Practise on 10 vignettes and check whether your first instinct matched the data.
Choosing an antibiotic or analgesic for an odontogenic infection without first deciding whether the collection is drainable and whether the airway or fascial spaces are involved, treating antibiotics as the primary treatment.
Textbook lists of drug choices are easier to memorise than the decision rule that antibiotics are adjunctive to removal of the cause and drainage; candidates also under-weight trismus, floor-of-mouth elevation and dysphagia because they are described briefly in the stem.
What to do instead
Build a one-page decision tree: is there airway risk or a spreading fascial space infection (admit, IV, drainage) versus a localised fluctuant swelling (incision and drainage plus extraction or pulpectomy, oral antibiotics only if systemic signs). Rehearse identifying the red-flag words in the stem before looking at options.
Extracting a tooth or planning surgery in a patient on anticoagulants or with a bleeding disorder by stopping the drug or by proceeding with no documented plan, rather than checking the indication, INR or current agent and planning local haemostatic measures.
Candidates conflate 'bleeding risk' with 'must stop the drug' and are unfamiliar with which agents (warfarin versus direct oral anticoagulants) need which checks; the stem often includes the INR or drug name but candidates ignore it.
What to do instead
Learn the rule that most dental extractions are managed without interrupting anticoagulation, using local measures (atraumatic technique, sutures, haemostatic agents, tranexamic acid mouthwash), and that INR and renal function guide liaison with the prescriber for DOACs. Practise writing the referral question you would send.
Answering restorative questions on the basis of the material or technique the candidate uses in practice rather than the evidence-based indication stated in the stem, for example choosing a composite for a large load-bearing posterior restoration or a crown when the stem describes a cracked cusp.
Habitual clinical practice and personal training bias feel authoritative, and candidates do not separate 'what I do' from 'what the evidence and the stem's clinical findings support'.
What to do instead
For each restorative option, write the indication and the contraindication in one line before choosing; if the stem's findings map to the contraindication column, eliminate it. Revise outcome data on posterior composites versus amalgam and on cuspal coverage so the choice is anchored to evidence rather than habit.
Missing the diagnosis of cracked tooth, occlusal trauma or non-carious cervical lesion because the candidate accepts the referral diagnosis in the stem and proceeds straight to treatment planning, without testing the diagnosis against the described symptoms (sharp pain on release of biting, localised probing depth, vitality response).
Stems are long and the diagnosis is often embedded early; candidates treat it as settled and spend their remaining time on the options, so a deliberately inconsistent detail goes unnoticed.
What to do instead
Always run a 15-second diagnostic audit: does the described pain pattern, vitality test and radiograph actually support the named diagnosis? If one finding contradicts it, the question is probably testing the alternative diagnosis. Practise listing the discriminating test for each common cause of tooth pain.
Interpreting a screening or epidemiological figure without checking the denominator, the age standardisation or the measure being reported, for example reading a prevalence as an incidence or comparing crude rates between two populations with different age structures.
Prevalence, incidence, DMFT and caries-free proportions are learned as vocabulary rather than as distinct measures, and candidates answer from the number that 'looks right' rather than from the definition.
What to do instead
Before answering any data question, state in one line what the numerator and denominator are and whether the measure is a count, a proportion or a rate. Practise converting between crude and age-standardised comparisons using a simple worked example until the distinction is automatic.
Designing or critiquing a community programme without specifying the target population, the setting, the outcome measure and the evaluation design, offering a list of activities (fluoride varnish, supervised brushing) as if activities were a plan.
Candidates memorise interventions but not programme logic, and exam stems asking for 'the most appropriate approach' reward the option that names who, where and how it will be measured.
What to do instead
Use a fixed template for every programme question: population and setting, evidence-based intervention, delivery agent, outcome indicator and evaluation method. Eliminate options that lack a measurable outcome or that target the wrong risk group.
Ignoring the medical history, pregnancy status or age-specific considerations when planning radiographs or prescribing, for example requesting a radiograph set that is not justified by the clinical indication or prescribing a tetracycline or NSAID without checking the contraindication in the stem.
Radiology and pharmacology are revised as separate lists, so the candidate does not connect the patient factors in the stem to the justification or contraindication being tested.
What to do instead
Make a one-page grid of common drugs against contraindications (pregnancy, asthma, renal impairment, peptic ulcer, anticoagulation) and a second on radiographic selection criteria by clinical presentation. Before answering, scan the stem for the one patient factor that changes the safe option.
Selecting the most invasive or most comprehensive treatment option when the stem describes a patient with limited prognosis, poor plaque control, uncontrolled diabetes or high caries risk, instead of addressing the risk factors first.
Candidates equate thoroughness with complexity and want to demonstrate knowledge of advanced treatment, missing that the question tests sequencing and risk-based planning.
What to do instead
Apply the sequence: stabilise and control disease, reassess, then restore or replace. If plaque control, glycaemic control or smoking is unresolved in the stem, the correct option is almost always the one that defers definitive complex work. Write the sequence out for three sample patients.
Managing time badly by spending disproportionate minutes on early difficult items and then guessing on later items, or by leaving multi-part clinical scenarios unanswered rather than making a reasoned choice.
Clinical vignettes feel solvable with more thought, so candidates over-invest; without a per-item time budget the final third of the paper is rushed, and unanswered items score zero where a reasoned elimination would have a chance.
What to do instead
Set a per-item time cap from the total items and total time, flag and move on when the cap is reached, and reserve the last minutes to return to flagged items and to ensure every item has an answer. Simulate this under timed conditions at least twice before the exam.