NZ Dental Technician REX common mistakes
NZ Dental Technician REX · Understand the traps and how to avoid them.
When asked to identify a tooth from a written description, the candidate names the tooth from memory of its shape alone and ignores the stated arch, quadrant and proximal surfaces, so a mesial-surface description of an upper first molar is answered as a lower molar or as the wrong tooth number.
Candidates learn 'picture-book' tooth morphology (number of cusps, root count) but do not rehearse the FDI two-digit system and the direction-specific use of mesial/distal/buccal/lingual. Under time pressure they pattern-match on a single feature (e.g. 'three roots = upper molar') and skip the systematic check.
What to do instead
Before answering, write out the FDI number from the arch and quadrant given, then verify each stated feature against that tooth: crown outline, cusp number and relative size, root number and curvature, and which surface carries which groove. Practise by covering the tooth name in a morphology table and reconstructing it from the FDI number alone until the mapping is automatic.
The candidate describes the muscles of mastication or the TMJ without linking each muscle to its origin, insertion and the specific mandibular movement it produces, so questions asking which muscle protrudes the mandible or which is the primary retrusor are answered with a plausible-sounding but wrong muscle.
Anatomy is memorised as lists of names rather than as functional chains. Candidates rarely rehearse the movement-by-movement breakdown (elevation, depression, protrusion, retrusion, lateral excursion) and confuse the lateral pterygoid's two heads or the role of the suprahyoid group.
What to do instead
Build a one-page movement table: for each mandibular movement, list the agonist, the antagonist and the joint action (hinge versus translation). Then test yourself by naming the movement from the muscle rather than the muscle from the movement. Rehearse the lateral pterygoid explicitly: inferior head protrudes, superior head retrudes and stabilises the disc.
When a question gives a material property (e.g. a flexural strength, a setting expansion or a thermal expansion coefficient) the candidate selects the material by name recognition of the brand or category rather than by comparing the stated numeric value against the known range for that class of material.
Materials are studied as product descriptions ('addition silicone is accurate') without the numeric anchors. Candidates do not hold working ranges in memory, so any number looks compatible with any material and the 'most likely' answer becomes a guess.
What to do instead
Maintain a numeric reference sheet for each material class: setting expansion of dental stone versus die stone, polymerisation shrinkage of acrylic versus composite, thermal expansion of porcelain versus metal, elastic modulus ranking. When a value is given, first bracket it (low, medium, high) and only then match to the class that occupies that bracket. Rehearse with values deliberately placed just outside the normal range so the boundary is learned.
In a complete-denture scenario the candidate answers about border moulding, posterior palatal seal or occlusal plane without first establishing the record stage (primary impression, secondary impression, jaw relation, try-in, processing) that the question describes, so the correct technique for the wrong stage is chosen.
Denture construction is learned as a list of steps but not as a decision tree keyed to the stage. Candidates skim the stem for a keyword ('border') and answer the border-moulding question even when the stem describes a try-in.
What to do instead
For every removable question, first write the stage in the margin, then ask what is physically present at that stage (which impression material, which record base, which teeth). Only then choose the technique. Drill with stems that describe the same procedure at two different stages and require different answers.
The candidate describes preparation design or die preparation for a crown or bridge without stating the minimum reduction for the chosen material, the finish-line configuration, or the need for a path of insertion, and answers 'adequate reduction' or 'chamfer' generically.
Fixed prosthodontics is studied from pictures of preparations rather than from the specifications that drive them. Candidates do not connect material (metal-ceramic, all-ceramic, zirconia) to its required thickness and margin design, so the answer cannot be specific.
What to do instead
Build a material-to-design matrix: for each restorative material record occlusal reduction, axial reduction, finish-line type and minimum connector cross-section. Answer fixed-prosthodontics questions by naming the material first, then quoting its numbers. Practise by converting every 'adequate' answer into a millimetre figure before selecting.
When asked about an orthodontic appliance the candidate describes the appliance's appearance but not its mode of action, the force level it delivers, or the biological response it depends on, so a question about which appliance produces bodily movement versus tipping is answered by appliance name alone.
Appliances are memorised as objects (Hawley, twin block, aligner) rather than as force systems. Candidates do not rehearse the relationship between force magnitude, centre of resistance and the resulting tooth movement.
What to do instead
For each appliance write three lines: active component, force level and direction, and expected tooth movement (tipping, bodily, intrusion, rotation). Then answer orthodontic questions by identifying the force system before naming the appliance. Rehearse the removable-versus-fixed functional appliance distinction with the same three-line template.
The candidate applies a general 'clean everything with disinfectant' rule and fails to distinguish instrument reprocessing steps (cleaning, disinfection, sterilisation, storage), the correct use of an autoclave indicator, or the difference between single-use and reusable items, so questions on reprocessing cycles or on handpiece sterilisation are answered with the wrong step.
Infection control is learned as a list of products rather than as a sequence with validated endpoints. Candidates do not rehearse what each step removes (bioburden versus viable organisms) or what a class B versus class N autoclave can process.
What to do instead
Draw the reprocessing chain as a numbered flow and annotate each step with its purpose, its monitoring method and its failure mode. Answer infection-control questions by locating the item in that chain before choosing an action. Rehearse the specific case of handpieces and of porous loads, which are the usual discriminators.
The candidate treats laboratory safety as generic workplace safety and does not distinguish the specific hazards of the dental laboratory: silica and PMMA dust, monomer vapour, acid and etchant exposure, and the correct control for each, so a question on ventilation or on respiratory protection for dust is answered with the wrong control hierarchy step.
Safety is studied from general workplace material rather than from the laboratory's own hazard inventory. Candidates do not rehearse the hierarchy of controls (elimination, substitution, engineering, administrative, PPE) and so cannot place a given control in the right rank.
What to do instead
List the laboratory's five main hazard classes and, for each, the engineering control (local exhaust ventilation, enclosed mixing, acid-resistant bench), the administrative control (exposure monitoring, training) and the PPE. Answer safety questions by naming the hazard class and then the highest-ranked control that applies. Rehearse why PPE is the last line of defence, not the first.
The candidate answers a scenario about consent, scope of practice, referral or cultural safety by applying a general 'be professional and communicate well' principle, without identifying the specific legal duty (informed consent, privacy of health information, mandatory reporting, competence boundary) or the relevant NZ framework, and without considering the patient's cultural context or whānau involvement.
Professional and legal content is studied as attitudes rather than as duties with defined triggers. Candidates do not rehearse the New Zealand frameworks (the Code of Health and Disability Services Consumers' Rights, the Privacy Act, the Health and Disability Commissioner process, cultural safety and Te Tiriti-based practice) and so cannot name the duty that the scenario actually tests.
What to do instead
Build a scenario-to-duty map: for each common scenario (a patient asks about a technician's role, a prescription is incomplete, a patient wants information shared with family), name the specific right or duty engaged, the required action and the escalation route. Rehearse cultural safety as a practical behaviour (asking about whānau involvement, using correct pronunciation, recognising power imbalance) rather than as a slogan, and practise naming the framework explicitly in the answer.
The candidate describes digital workflows as file formats and equipment names without linking each step to its quality-control checkpoint, so a question about scan accuracy, design approval, nesting, milling or 3D-printing validation is answered by naming the device rather than the verification step that must occur before the next stage.
Digital workflows are learned as a sequence of software and hardware, not as a chain of verifiable handoffs. Candidates do not rehearse where errors enter (scan stitching, die spacer, intaglio relief, print orientation, post-processing) or what evidence confirms the step succeeded.
What to do instead
Draw the digital chain from intraoral or model scan to fit and annotate each handoff with its QC check (scan completeness, margin capture, design approval against prescription, nesting and support placement, post-cure and fit verification). Answer digital questions by locating the stage and naming its check. Rehearse the printed-versus-milled distinction and the specific post-processing steps each requires.