# RDA exam practice questions: Diagnostic tests and records Five original RDA exam practice questions on diagnostic tests and records, each answered on this page with a rationale and a source. Last updated: 2026-07-25. ## Question 1 During a crown appointment the dentist asks the RDA to capture the intraoral images for a CAD-milled restoration, and later asks her to take the final impression for a laboratory-fabricated bridge. What is the correct scope analysis? - A. Both are RDA duties, because each one captures the geometry of the finished preparation. - B. Neither is an RDA duty; both belong to the treating dentist alone. - C. Both are RDA duties, but each one requires direct supervision rather than general supervision. - D. The CAD imaging is an RDA duty; the final impression is an RDAEF extended function. **Answer D:** The CAD imaging is an RDA duty; the final impression is an RDAEF extended function. BPC §1752.4 expressly authorizes an RDA to obtain intraoral images for CAD-milled restorations under general supervision, while taking final impressions for permanent indirect restorations is an RDAEF extended function under BPC §1753.5. **Common trap:** the exam blurs the two because both capture preparation geometry — the named CAD-imaging duty is the RDA's and nothing more. 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 2 A general practice in Fresno is running a normal Tuesday. The owner dentist leaves at noon for a hospital consult, having given standing instructions for the afternoon's recall patients. The RDA uses an automated laser fluorescence caries detection device on a recall patient's suspect lower molar and records the numeric readings by tooth and surface in the chart. Which statement best describes this? - A. Unlawful, because automated caries detection devices may be used only while the dentist is physically present in the treatment facility. - B. Lawful, because using an automated caries detection device and recording the findings is an RDA duty under general supervision. - C. Lawful only if the assistant holds an RDAEF license, because caries detection devices are an extended function. - D. Unlawful, because detecting caries is a diagnostic act that may never be delegated to any dental auxiliary. **Answer B:** Lawful, because using an automated caries detection device and recording the findings is an RDA duty under general supervision. BPC §1752.4 expressly lists the use of automated caries detection devices and materials, and the recording of those findings, among the duties an RDA may perform under general supervision, and the Board's Table of Permitted Duties effective January 1, 2025 marks that duty G for RDAs. General supervision means the procedure is based on the dentist's instructions and does not require the dentist's physical presence, unlike direct supervision, which does. Running the device and recording numbers is data collection; the dentist still interprets the data. **Common trap:** Option D confuses detecting with diagnosing — the device produces a reading, and only the dentist turns that reading into a diagnosis, so operating the device is delegable while the diagnosis is not. Option A applies the direct-supervision rule to a general-supervision duty, and option C invents an RDAEF requirement the statute does not impose. 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 An RDA is about to take a laser fluorescence reading on the occlusal surface of tooth #30. The fissures hold heavy plaque and brown stain, and the tooth is still wet from the prophylaxis rinse. What should the RDA do first? - A. Take the reading now and add a chart note that heavy plaque and stain were present. - B. Clean and dry the surface, then calibrate the unit per the manufacturer before reading. - C. Apply a caries indicator dye first, because dye readings are unaffected by plaque and moisture. - D. Tell the patient the dark stain means decay, and record a carious lesion on the occlusal of #30. **Answer B:** Clean and dry the surface, then calibrate the unit per the manufacturer before reading. Plaque, calculus, stain, and moisture all produce false readings on a laser fluorescence unit, which will report stain as though it were decay, so the standard procedure is to clean and dry the surface, calibrate or zero the device per the manufacturer, then read systematically and record the values by tooth and surface. An uncalibrated reading on a contaminated surface gives the dentist unreliable data to diagnose from. **Common trap:** Option A is tempting because documenting the confounder feels diligent, but a knowingly unreliable reading is not a usable diagnostic record. Option D goes further and crosses the legal line — telling the patient a finding "means decay" is diagnosis, which no assistant category may perform. 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 4 In a San Jose office, the dentist preps a molar for a chairside-milled crown, gives instructions, and leaves for the day. The RDA obtains intraoral digital scans of both arches and the bite so the restoration can be designed and milled. A coworker insists this was illegal, saying "only an RDAEF can take an impression for a permanent indirect restoration." Who is right? - A. The coworker — a digital scan counts as the final impression for the crown, so state law requires an RDAEF license. - B. The RDA — obtaining intraoral images for computer-aided design (CAD) milled restorations is its own named RDA duty under general supervision. - C. The coworker — the scan is an RDA duty, but only under direct supervision, so the dentist's departure made it unlawful. - D. Neither — no auxiliary of any category may capture an impression or a digital scan of a prepared tooth. **Answer B:** The RDA — obtaining intraoral images for computer-aided design (CAD) milled restorations is its own named RDA duty under general supervision. BPC §1752.4 names "obtaining intraoral images for computer-aided design (CAD), milled restorations" as an RDA duty, and the Board's Table of Permitted Duties effective January 1, 2025 marks it G, so the dentist's physical presence is not required. Final impressions for permanent indirect restorations sit in the RDAEF statute (BPC §1753.5), a different duty with a different license. The exam tests that these are two separately named authorities, not one blurred category. **Common trap:** This is a stale-prep trap. Duty charts and study guides printed before January 1, 2025 misstate assisting scope and supervision levels, and many older materials collapse "scan" and "impression" into a single RDAEF-only line. The Board's 2025 table controls over any older chart. 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 5 During a full-arch intraoral scan, the wand optics fog repeatedly as the RDA moves into the posterior, and the on-screen model shows several holes plus a bulge of cheek tissue modeled along the buccal of the prepared tooth. What is the best explanation and correction? - A. A cold tip in warm breath fogged the optics and thin retraction let the cheek in — warm the tip, retract, and rescan. - B. The operatory light is too dim for the optics; aim the overhead light into the field and rescan the arch. - C. The patient's saliva is unusually thick; dry the arch and apply the scanning powder these systems require. - D. Nothing needs correcting — the design software fills the holes automatically, so the scan can be milled as captured. **Answer A:** A cold tip in warm breath fogged the optics and thin retraction let the cheek in — warm the tip, retract, and rescan. Standard references identify moisture, patient or wand movement, optics fogging from a cold tip, inadequate retraction, a dirty or badly angled tip, missed areas, and strong ambient light as the recurring causes of an unusable digital scan. A poor scan produces a poor-fitting milled restoration, so the model is inspected for voids and distortions on screen and the deficient segment rescanned while the patient is still in the chair. **Common trap:** Option C relies on outdated technique — some older systems required scanning powder, but most current systems are powder-free, so no powder is called for here. Option B inverts the light factor, since strong ambient light washes out a capture rather than improving it, and option D assumes software can invent surface data it never received. Source: Bird DL, Robinson DS. Modern Dental Assisting. Current edition, Elsevier. (Record the exact edition in the source registry when first cited for a… ## 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.