RDA (Other exams) common mistakes
RDA · Understand the traps and how to avoid them.
Answering the phone, typing on the keyboard, or pulling a chart out of the drawer while still wearing the gloves used on the patient, then returning to the patient without changing gloves.
Candidates treat gloves as personal protection ('my hands stay clean') instead of a patient-to-surface barrier, so they never build the habit of separating 'clean touch' tasks from 'contaminated touch' tasks.
What to do instead
Before the exam, drill the rule 'gloves on = patient only, gloves off = everything else.' Practise the sequence out loud: remove gloves, perform hand hygiene, touch the chart/phone/computer, don new gloves before re-entering the patient's field. On scenario items, look for the option that breaks the chain at the touch point rather than one that just says 'wash hands.'
Assigning an item to the wrong reprocessing category - for example, sending a handpiece, ultrasonic scaler tip, or extraction forceps to low-level disinfection, or heat-sterilizing a plastic item that only needs wiping.
Candidates memorise a list of 'things we sterilize' without the underlying Spaulding logic, so any unfamiliar instrument on the exam becomes a guess.
What to do instead
Anchor everything to the three categories: critical (penetrates tissue/bone or contacts blood - must be sterile), semicritical (contacts intact mucosa - sterilization preferred, high-level disinfection acceptable), noncritical (contacts intact skin only - low-level disinfection). Classify each instrument in your head as 'would blood touch it, would it enter tissue, or would it only touch skin?' before reading the answer choices.
Explaining that increasing the mA will change image contrast, or that increasing kVp will increase the number of x-rays produced without affecting penetration, and choosing these as the answer to 'how do you reduce patient dose' or 'how do you darken a light film.'
The four exposure variables (mA, kVp, time, distance) get memorised as a list rather than as two separate dimensions - quantity of photons versus quality/penetrating power - so they get swapped under time pressure.
What to do instead
Fix the pairing in memory: mA × time = quantity (number of photons, controls density/darkness); kVp = quality (penetrating power, controls contrast and also multiplies dose). Then attach the safety rules: reduce dose by increasing collimation, increasing filtration, using the faster film/sensor, and using a longer PID - not by lowering kVp blindly. Write the pair out from scratch each study session until it is automatic.
Approving or choosing an answer where the patient or the operator holds the image receptor in place, or where the operator stands in line with the primary beam 'as long as they are behind the barrier.'
Candidates conflate 'as low as reasonably achievable' with 'as convenient as possible' and underestimate how much of a dose question is about the primary beam specifically rather than distance in general.
What to do instead
Memorise the absolute rules: never let a patient or a staff member hold the receptor; the operator stands at least 6 feet from the source at an angle of 90–135 degrees to the primary beam, behind a barrier if available; only the patient may be in the room. Any exam option containing 'patient holds' or 'operator holds' is wrong regardless of how protective the rest of the sentence sounds.
Passing an instrument by the handle with the working end pointed toward the operator's palm or across the patient's face and chest, and transferring a sharp before the operator has acknowledged it.
Candidates focus on memorising the names of the transfer motions and forget that the entire rationale is sharps safety and patient comfort, so they pick whichever transfer position 'sounds technical.'
What to do instead
Practise the physical motions with a pen until they are muscle memory: the instrument is delivered with the handle toward the receiving hand, working end directed away from the patient, in the same zone near the mouth - never over the face. Confirm the operator has gripped it before releasing. If a question asks about transfer position, the answer is the one that keeps the working end low, pointed away, and inside the transfer zone.
Holding the high-volume evacuator far from the tooth or resting it on the floor of the mouth, and answering isolation questions by choosing a rubber dam or suction device without matching it to the procedure described.
Candidates treat evacuation as a comfort item rather than a clinical control, so they never consider proximity, tissue retraction, or which procedures actually require a dry field (sealants, composites, endodontics).
What to do instead
Learn the principle 'tip as close to the operative site as possible, bevel toward the tooth, and use the same instrument to retract the cheek and tongue.' Then build a matching list: rubber dam for endodontics, sealant placement, and any adhesive bonding; cotton rolls plus HVE for shorter restorative work; dry-angle or similar for isolated quadrants. Match the isolation answer to the moisture sensitivity of the material, not to what is quickest.
Scooping alginate powder by eye or 'fluffing' the powder in the can, then pouring the impression hours later or soaking it in water, and stating the impression can be stored indefinitely.
Candidates learn the mixing steps but not the material's dimensional behaviour, so any question framed around impression accuracy after storage reads as a memory item rather than a reason-to-effect question.
What to do instead
Attach three facts to irreversible hydrocolloid: it must be proportioned by weight or the supplied scoop and water measure (not by eye, and fluffed to avoid packing), it loses water by syneresis if left dry and gains water by imbibition if soaked, and it should be poured promptly (within roughly the working window, or stored damp for a limited time only). On exam items, the answer is almost always 'pour immediately' or 'store in a sealed bag with a damp paper towel until pouring.'
Mixing zinc phosphate cement on a warm or un-cooled glass slab, or choosing a cement for an indication based on 'cement means it sticks' rather than on the material's specific properties (film thickness, pulp irritancy, moisture tolerance, fluoride release).
Candidates memorise brand-level steps without the property that drives the step, so they cannot answer 'why is the slab cooled' or 'which cement for a high-strength metal restoration.'
What to do instead
Learn cements by property triangle: zinc phosphate (strong, acidic, exothermic - work on a cooled slab to slow the reaction and extend working time), glass ionomer (fluoride release, bonds to tooth, moisture-sensitive), resin-based (no acid, adhesive, used for bonding), polycarboxylate (adheres to tooth and metal, gentle on the pulp). Cool the slab, spatulate in small increments over a large area, and let it reach a glossy/string stage before seating.
Correcting an entry by writing over it, using white-out, or back-dating a late entry as though it was written at the time of the appointment; or recording 'no known allergies' when the question was never actually asked.
Candidates treat the chart as a note-taking pad rather than a legal document, so they select whatever makes the record look tidy instead of what preserves accuracy and accountability.
What to do instead
Apply the legal-record rules to every charting question: entries are contemporaneous, dated, timed, and signed or initialled; corrections are a single line through the error with 'error' or the correction, plus initials and date - never obliteration or erasure; late entries are marked as late additions with the actual date of entry. Never write a negative finding that was not verified. If an option makes the record look cleaner but less true, it is wrong.
On ethics and administrative scenarios, disclosing or discussing patient information in a hallway, at the front desk, or on a personal phone, and acting on a treatment decision that belongs to the dentist or hygienist's scope rather than recognising it as outside the assistant's role.
Candidates study confidentiality and scope of practice as abstract vocabulary, so on a scenario item they choose the option that is most helpful or efficient rather than the one that is permissible.
What to do instead
For every scenario, run two questions before selecting: (1) 'does this share more than the minimum necessary, and who is entitled to know it?' and (2) 'is this decision assigned to my scope, or must it be referred to the dentist?' Confidentiality questions resolve to the least-disclosing option that still accomplishes the task; scope questions resolve to the option that assists and prepares but does not independently diagnose, prescribe, or treat. When two answers both seem right, discard the one that expands the assistant's authority or the circle of people with access.