# RDA exam practice questions: Treatment preparation Five original RDA exam practice questions on treatment preparation, each answered on this page with a rationale and a source. Last updated: 2026-07-25. ## Question 1 One week after a Class II amalgam, the patient's floss shreds at the gingival margin, and a ledge of material is visible below the contact. Which preparation step most likely failed? - A. The etchant was left on the preparation for too long. - B. The liner was placed too thickly across the pulpal floor. - C. The curing light was held too far from the restoration. - D. The wedge was omitted, undersized, or misplaced. **Answer D:** The wedge was omitted, undersized, or misplaced. The wedge adapts the band against the gingival margin, seals that edge against extruded material, and separates the teeth so the contact closes when the band is removed; a gingival ledge that shreds floss is the signature of a wedge failure. **Common trap:** distractors blame the etchant, liner, or curing light — answer with the preparation step whose job description matches the damage. Source: Bird DL, Robinson DS. Modern Dental Assisting. Current edition, Elsevier — the standard clinical dental-assisting reference used for Areas 1–3… ## Question 2 During a restorative appointment the dentist steps into the adjacent operatory in the same office and asks the RDA to place the liner and base she ordered. The RDA thinks the preparation looks shallow and decides on her own to skip the base. What is the problem? - A. The dentist was not physically in this operatory, so the delegation of the base was unlawful. - B. Deciding a preparation does not need a base substitutes her judgment for the dentist's. - C. Nothing — an experienced assistant may adjust the material sequence at the chair herself. - D. Bases and liners may be placed only by an RDAEF under direct supervision. **Answer B:** Deciding a preparation does not need a base substitutes her judgment for the dentist's. Placing bases and liners is an authorized RDA duty under BPC §1752.4(a)(7), which subdivision (a) authorizes under general supervision (marked G on the Board's table) — but deciding whether a preparation needs a base is diagnosis and treatment planning, excluded from every assisting category under BPC §1750.1(d). **Common trap:** the location distractor fails twice over — the dentist in the adjacent operatory would satisfy direct supervision anyway ("physically present in the treatment facility" means the building), and no direct-supervision requirement applies here absent a §1752.4(d) determination or the narrower 16 CCR §1086(d)(4) row for bases and liners on sound dentin. The violation is the clinical decision, not the location or the supervision level. Source: [California Business & Professions Code §1752.4 — RDA duties and supervision levels. Subdivision (a) lists the RDA's duties, performed "under general…](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1752.4.&lawCode=BPC) ## Question 3 A patient walks into a Fresno general practice with a swollen left cheek and a throbbing lower molar. The dentist's examination also documents six carious lesions, a missing first molar, and generalized gingivitis, and the dentist writes a full treatment plan. Which phase of that plan does the RDA prepare the operatory for at this visit? - A. The definitive or corrective phase — begin the fixed bridge that will replace the missing first molar. - B. The emergency or urgent phase — relieve the pain and infection in the symptomatic molar first. - C. The maintenance phase — schedule and set up a series of three-month recall visits before any operative care. - D. The disease-control phase — restore all six carious lesions in one long appointment today. **Answer B:** The emergency or urgent phase — relieve the pain and infection in the symptomatic molar first. Standard references sequence a treatment plan as an emergency or urgent phase that relieves pain and infection, then a disease-control phase that arrests active caries and periodontal disease, then a definitive or corrective phase that rebuilds function and appearance, then a maintenance phase of recall visits. The acute swelling and pain place this visit squarely in the first phase, and the setup follows the phase the dentist has ordered. The assistant never selects the phase independently, because diagnosis and treatment planning belong to the dentist alone and are excluded from every assistant category by statute. **Common trap:** Choice A is tempting because the missing molar is the most visible problem and the patient may be asking about it, but definitive prosthetic care follows pain control and disease control. Choice D confuses "disease control" with "do everything at once." Any option in which the assistant decides which phase comes first also hands the dentist's treatment-planning role to the assistant, which is always wrong. Source: [California Business & Professions Code §1750.1 — basic supportive dental procedures delegable to unlicensed dental assistants (general- vs…](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1750.1.&lawCode=BPC) ## Question 4 An RDA in a Sacramento office is laying out a preset tray for a Class II amalgam restoration. How should the instruments be arranged on the tray? - A. Grouped by material — all metal instruments together, all plastic and disposable items together. - B. Left to right in the sequence they will be used, with the examination instruments (mouth mirror, explorer, cotton pliers) placed first. - C. Right to left in the sequence they will be used, with the carving instruments first because they are in the dentist's hand the longest. - D. In whatever order they came out of the sterilization pouch, since the dentist names each instrument when it is needed. **Answer B:** Left to right in the sequence they will be used, with the examination instruments (mouth mirror, explorer, cotton pliers) placed first. The house rule for arranging a tray is sequence of use: instruments are laid out left to right in the order the procedure will call for them, with the basic examination setup — mouth mirror, explorer, cotton pliers — first. Arranging by sequence of use is what makes instrument transfer flow without hunting, and preset trays or tubs organized by procedure, often color-coded, standardize that arrangement across the office. **Common trap:** Choices A and D describe habits that exist in real offices but are not the tested standard; the exam treats the preset, sequence-of-use system, not the assistant's memory or the dentist's verbal requests, as the correct way an office prevents missing-instrument delays. Choice C reverses the direction and puts a late-procedure instrument group at the front. Source: Bird DL, Robinson DS. Modern Dental Assisting. Current edition, Elsevier. (Standard clinical reference for chairside technique where no statute… ## Question 5 An RDA carries a wrapped instrument cassette to the chairside for a restorative appointment in a San Diego practice. The external process indicator on the wrap has changed color, but the RDA notices a small tear along one edge and a damp spot on the underside of the package. What is the correct action? - A. Use the instruments, because the color change on the external process indicator confirms the load was sterilized. - B. Wipe the outside of the package with a surface disinfectant, then open it at the point of use as originally planned. - C. Treat the contents as not sterile and return the package to the processing area for cleaning, repackaging, and re-sterilization. - D. Open the package now and let the damp instruments air dry on the tray before the patient is seated in the chair. **Answer C:** Treat the contents as not sterile and return the package to the processing area for cleaning, repackaging, and re-sterilization. The California Minimum Standards for Infection Control require sterilized items to be packaged and stored in a way that maintains sterility until the point of use, which makes packaging-and-storage discipline a regulatory duty rather than an office preference. A package that is torn, punctured, or wet has lost sterility no matter what the indicator shows or how recently the load was run, and the contents must be reprocessed. Sterile packages are also opened at the point of use, in front of the procedure they serve, after the assistant checks both the indicator and the package's integrity. **Common trap:** Choice A treats a process indicator as proof of maintained sterility; an indicator shows only that the package was exposed to the sterilization process, not that the barrier survived intact. Choice B is the classic "wiped off is good enough" shortcut, which 16 CCR §1005 does not allow. Choice D compounds the error by opening a compromised package early. Source: [16 CCR §1005 — Minimum Standards for Infection Control (Dental Board of California): standard precautions, critical/semi-critical/noncritical items,…](https://govt.westlaw.com/calregs/) ## Next step [Take the free 15-question practice test](https://dentovio.com/rda/free-practice-test) Official reference: [Dental Board of California RDA Combined Written and Law and Ethics Examination Outline](https://www.dbc.ca.gov/formspubs/rda_exam_outline.pdf). Original exam-style questions written for study, never recalled exam content. Independent educational preparation, not legal or clinical advice, and not affiliated with or endorsed by the Dental Board of California or PSI. Confirm current requirements with the Dental Board of California.