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ADEX exam

ADEX Restorative Errors & Fail Points – Mistakes to Avoid

A focused guide to the common preparation and restoration errors that cost marks in the ADEX manikin and OSCE components.

Quick Answers

What are the main restorative fail points in ADEX?

Breaking enamel margins, over-reduction, open contacts, overhanging margins, and pulp or adjacent tooth damage.

What do examiners want from your prep?

Clear margins, adequate but not excessive reduction, proper resistance and retention form, and respect for anatomy.

What occlusal errors lose marks?

High spots, open centric contacts, flat anatomy, or destroying functional cusps unnecessarily.

How can you quickly reduce risk of failure?

Follow a checklist, verify reduction, protect adjacent teeth, and constantly re-check margins before submitting.

Is speed important?

Speed matters less than control. A slower, neat preparation usually scores higher than a rushed one with multiple errors.

1. How examiners look at restorative work in ADEX

In the ADEX manikin and restorative stations, examiners are not trying to trick you. They use a rubric based on margin quality, reduction, contact, contour, and occlusion. Most candidates lose marks because of repeated basic errors, not rare complications.

Your goal is to avoid obvious mistakes and produce a preparation and restoration that looks clean, conservative, and functional.

2. Common preparation errors

High-yield prep errors that cost marks in class II, class III, and crown preparations include:

  • Over-reduction of cusps or axial walls.
  • Undercuts or irregular walls that compromise retention.
  • Unsupported enamel at the margin.
  • Margins on steep inclines instead of gentle planes.
  • Breaking the contact too wide or not breaking contact at all when required.
  • Damaging adjacent teeth during access.

A simple way to avoid these errors is to pause and inspect every wall and margin before moving to the next step.

3. Common restoration errors

After placement of composite or amalgam, ADEX examiners often see:

  • Open contacts or excessively tight contacts.
  • Overhanging margins at the gingival area.
  • Poor marginal adaptation and visible gaps.
  • Flat occlusal anatomy with lost grooves and ridges.
  • High occlusion or non-functional contacts.

Many of these issues can be reduced with careful matrix placement, wedge selection, and checking contact and occlusion early.

4. Fail-point patterns examiners see repeatedly

Across many exams, the same patterns appear:

  • Cutting too deeply into the pulp chamber area during preparation.
  • Over-tapering crown preps and leaving minimal axial wall height.
  • Rough, jagged margins that are difficult to restore.
  • Ignoring proximal contour and leaving food-trap spaces.
  • Submitting work without checking occlusion properly.

In borderline cases, a candidate who shows clear control and conservative choices often passes even with small imperfections.

5. Simple strategies to avoid restorative failure

  • Use a step-by-step mental checklist before and after each preparation.
  • Protect adjacent teeth with matrices or wedges when opening contacts.
  • Measure and confirm reduction, rather than guessing.
  • Refine margins with light pressure and smaller burs instead of aggressive cutting.
  • Check contacts with floss and adjust gently rather than leaving them open or excessively tight.

These strategies reduce panic and let you produce predictable work, even under time pressure.

6. Fast memory points

  • Avoid over-reduction and unsupported enamel at all margins.
  • Protect adjacent teeth and confirm contact quality.
  • Preserve functional cusps and basic occlusal anatomy.
  • Check and refine margins before you call a preparation finished.
  • Control and consistency impress examiners more than speed.

How DentAIstudy helps

With DentAIstudy’s Study builder, you can generate:

  • Lists of common ADEX restorative errors for rapid review.
  • Scenario-based questions on fail points in class II and crown preparations.
  • Checklists to use when mentally reviewing your work on exam day.
  • Flashcards focused on contact, contour, and occlusion criteria.

Try Study Builder →

References

  • CDCA-WREB-CITA restorative grading guidelines and candidate manuals.
  • Standard operative dentistry texts for tooth preparation and restoration criteria.
  • Common clinical checklists used in preclinical restorative courses.