# California RDA Exam Area 2B: Direct and Indirect Restorations

What Area 2B of the California RDA exam tests: temporary fillings, etching, bonding and provisionals, with the RDA duty limits and common traps.

Area 2B · 10% of the California RDA exam. Last updated 2026-09-23.

Direct and Indirect Restorations (Area 2B) makes up 10% of the California RDA Combined Written and Law and Ethics Examination. This section tests the restorative core of chairside assisting, including temporary fillings, etching, bonding, provisional fabrication, cement removal, and assisting with nitrous oxide. Mastering this area matters because it blends standard clinical technique with strict legal boundaries, requiring you to know exactly which procedures belong to the RDA and what level of supervision the law demands for each task.

## At a glance

| Detail | What the sources establish |
| --- | --- |
| **Exam weight** | Area 2B is 10% of the exam, roughly 10 of the 100 scored items. [^B1] |
| **Provisional vs. permanent** | RDAs place, adjust, and finish direct provisionals and fabricate, cement, and remove indirect provisionals. [^A8] Placing, finishing, and adjusting permanent restorations belongs to the dentist or an RDAEF licensed on or after January 1, 2010, not to an RDA. [^A9] |
| **Supervision baseline** | Etch, bond, provisionals, and hand-instrument cement removal are authorized under general supervision by default. [^A8] |
| **Dentist's discretion** | The supervising dentist may determine case-by-case that a general-supervision restorative duty requires direct supervision. [^A8] |
| **Cement removal** | An RDA removes excess cement using a hand instrument; ultrasonic removal for orthodontic patients requires completion of a Board-approved course. [^A8] |
| **Nitrous oxide** | Adjusting the flow requires the dentist's direction and presence in the operatory; starting the flow is excluded from assistant duties. [^A4] |

## What the exam expects you to know

### T14 — Place temporary filling materials

A temporary filling seals and protects a prepared or broken tooth between appointments. The main families of temporary materials are zinc oxide–eugenol (ZOE), premixed provisional materials, and glass ionomer. ZOE is the classic choice because eugenol has a soothing, sedative effect on an irritated pulp. Premixed materials set on contact with moisture, making them a fast seal for endodontic access openings. Glass ionomer releases fluoride and chemically bonds to the tooth structure. [^C1] 

The choice of material matters clinically and legally. Eugenol interferes with the setting of resin materials. If the final restoration will be a bonded composite, you must use a eugenol-free temporary material. [^C1] Legally, placing a direct provisional restoration is authorized under general supervision, marked "G" on the Board's table, though the supervising dentist may require direct supervision for a specific procedure. [^A8] [^B5]

### T15 and T16 — Apply etchant and bonding agents

Etchant is a mild acid, typically 30 to 40 percent phosphoric acid, that microscopically roughens enamel and dentin so bonded materials can grip the tooth. You must apply the etchant only to the surfaces being bonded for the exact time the manufacturer specifies. Over-etching damages dentin and weakens the bond. After rinsing and drying, properly etched enamel looks frosty and chalky white, while dentin should be left slightly moist rather than completely desiccated. [^C1] 

The bonding agent is the thin resin adhesive layer that links the etched tooth to the restorative material. It is applied in a thin coat, gently air-thinned to evaporate the solvent, and light-cured. If saliva or blood touches the etched or bonded surface at any point, the surface is contaminated and you must re-isolate and re-etch. [^C1] Applying etchant and bonding agents are both duties native to the general-supervision list, subject to the dentist's case-by-case discretion to require direct supervision. [^A8]

### T17, T18, and T19 — Fabricate, adjust, and cement indirect provisionals

An indirect provisional is a custom provisional crown or bridge, as opposed to a direct provisional filling. It is typically formed from acrylic resin or bis-acryl composite in a matrix, either on the prepared tooth or on a model, and finished outside the mouth. The standard sequence involves capturing the tooth's shape with a matrix before the dentist prepares the tooth. After preparation, the matrix is loaded with provisional material and seated. The critical timing step is removing the provisional while the material is still rubbery and elastic so it does not lock into undercuts. It then finishes setting outside the mouth. [^C1]

Before cementation, the provisional must pass three checks. You evaluate margins with an explorer to ensure there are no gaps or overhangs. You test proximal contacts with dental floss, looking for a slight snap. You check occlusion with articulating paper to ensure the bite is even and not high. [^C1] Provisionals are seated with temporary cements, such as ZOE or eugenol-free zinc oxide cements, designed for moderate retention and easy removal. Fabricating, adjusting, and cementing indirect provisionals are listed at general supervision in §1752.4(a), subject to the dentist's determination. [^A8] The Board's table also lists narrower 16 CCR §1086 rows, such as fabricating temporary crowns intraorally and sizing stainless steel crowns, at direct supervision. [^A22] [^B5]

### T20 and T21 — Place, adjust, and finish direct provisionals

A direct provisional is formed directly on or in the prepared tooth in the patient's mouth. It requires the exact same evaluation triad as an indirect provisional: an explorer for margins, floss for contacts, and articulating paper for occlusion. [^C1] 

Finishing turns an adjusted provisional into a smooth, cleansable surface. You work from coarser to finer abrasives, using finishing burs, abrasive discs, and polishing points. Improper finishing is a clinical failure. A rough surface accumulates plaque and inflames the gingiva; open margins allow leakage and sensitivity; and a high spot in occlusion causes biting pain and can fracture the provisional. [^C1] Placing, adjusting, and finishing direct provisionals are general-supervision duties, subject to the dentist's discretion. [^A8]

### T22 — Remove excess cement

After any cementation, leftover cement must be removed from the teeth and the gumline. For an RDA, the authorized tool for removing excess cement is a hand instrument, such as a scaler, followed by an explorer to check the margins and knotted floss to clear the interproximal contacts. [^C1] 

Retained cement acts like a permanent piece of debris. The adjacent gingiva becomes red, swollen, and tender, and it will bleed when brushed. If a patient returns days after cementation with localized gingival inflammation, residual cement is the likely cause. [^C1] Legally, removing excess cement with a hand instrument is a general-supervision duty. Removing excess cement with an ultrasonic scaler from supragingival surfaces of teeth undergoing orthodontic treatment is an additional RDA duty that requires completion of a Board-approved course. [^A8]

### T23 — Assist with nitrous oxide and oxygen

The assistant's role with nitrous oxide is to assist. An assistant may adjust the flow of nitrous oxide and oxygen gases only if the supervising dentist deems it necessary and directs it, and the dentist must be present in the operatory directly supervising the adjustment. Starting the flow of nitrous oxide and oxygen is on the statutory list of procedures excluded from dental assistant duties, and it is not among an RDA's listed duties. [^A4] [^A8]

During administration, you must watch for signs of oversedation, which include nausea, vomiting, sweating, dizziness, sluggish responses, or an inability to keep the mouth open. If these occur, you must alert the dentist immediately. At the end of the procedure, the patient must breathe pure oxygen for several minutes to wash out the nitrous oxide; skipping this step risks diffusion hypoxia, which leaves the patient lightheaded or nauseated. [^C1]

## Common traps

*   **Assuming restorative duties are categorically direct supervision.** Tempting, but incorrect. Bases, liners, etch, bond, provisionals, and hand-instrument cement removal are native to BPC §1752.4(a), where general supervision is the statutory starting point. The dentist may require direct supervision under subdivision (d), and the Board's table lists narrower 16 CCR §1086 rows, such as intraoral temporary-crown fabrication and sizing stainless steel crowns, at direct supervision. [^A8] [^A22] [^B5]
*   **Finishing a permanent composite because the motion is the same.** The category of the restoration dictates the scope, not the hand movement. Placing, finishing, or removing permanent restorations is excluded for dental assistants and RDAs, with a narrow exception letting RDAEFs licensed on or after January 1, 2010 place, contour, finish, and adjust direct restorations. [^A4] [^A9] [^A22]
*   **Using ZOE temporary cement under a planned bonded restoration.** Eugenol interferes with the polymerization of resin materials. If the treatment plan calls for a bonded resin restoration next, the interim materials must be eugenol-free. [^C1]
*   **Over-drying dentin to get a better bond.** "Longer and drier is better" is a clinical error. Desiccated dentin bonds poorly. Properly etched enamel is frosty and chalky white, but dentin must be left slightly moist. [^C1]
*   **Using an ultrasonic scaler for routine cement removal.** The RDA's restorative cement removal authorization is strictly limited to using a hand instrument. Ultrasonic cement removal for teeth undergoing orthodontic treatment is an additional RDA duty requiring completion of a Board-approved course. [^A8]
*   **Starting the nitrous oxide flow because the dentist is in the room.** A dentist's presence or a hallway order does not change the law. Starting the flow of nitrous oxide and oxygen is excluded from dental assistant duties, and an adjustment requires the dentist in the operatory. [^A4]

## Check yourself

Answer the original practice item, then take the free 15-question practice test to see every area.

## How to study this area

Area 2B is worth 10% of your exam, roughly 10 of the 100 scored items. Because this area blends clinical chairside technique with strict legal boundaries, you cannot rely on office habit alone. You must study the standard textbook procedures alongside the California Dental Practice Act and the Board's Table of Permitted Duties effective January 1, 2025. 

Focus your study time on the exact boundaries of your scope. Expect questions that ask you to recognize when a clinical scenario crosses from a permitted provisional duty into a prohibited permanent duty. 

1.  **Memorize the provisional boundary:** If a stem says "permanent" or "final," the duty belongs to the dentist or a post-2010 RDAEF. 
2.  **Anchor the supervision rules:** Know that native restorative duties start at general supervision, but the dentist holds the power to require direct supervision case-by-case, and a few Board-table 16 CCR §1086 rows are marked direct.
3.  **Master the materials chemistry:** Lock in the rule that eugenol and resin do not mix, and that contamination requires re-etching.
4.  **Learn the evaluation triad:** Always pair the explorer with margins, floss with contacts, and articulating paper with occlusion.

## Questions candidates ask

### Do I need to memorize specific etching times?
You do not need to memorize a universal etching time because one does not exist. The standard rule is that you must apply the etchant for the exact time the manufacturer specifies. Over-etching damages the dentin and weakens the bond, so following the product's specific directions is the only correct clinical answer. [^C1]

### What happens if a provisional is left in the mouth too long during fabrication?
If a matrix loaded with provisional material is left on the prepared tooth past the rubbery stage, the material will fully harden and lock into the tooth's undercuts. This makes it incredibly difficult to remove without damaging the preparation. The provisional must be removed while it is still elastic and allowed to finish setting outside the mouth. [^C1]

### Can I monitor a sedated patient if I have enough chairside experience?
Experience alone is not enough. The sedation-monitoring duties in BPC §1750.5 belong to the dental sedation assistant (DSA) permit, which has its own prerequisites and written examination. An RDA may perform those duties only after completing a Board-approved RDA educational program or Board-approved course in them. [^A6] [^A8]

[^A4]: California Business & Professions Code §1750.1 — basic supportive dental procedures delegable to unlicensed dental assistants and the never-delegable exclusions in subdivision (d). [California Business & Professions Code §1750.1](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1750.1.&lawCode=BPC)
[^A6]: California Business & Professions Code §1750.5 — dental sedation assistant (DSA) permit: permitted sedation-related duties, prerequisites, and the separate written examination. [California Business & Professions Code §1750.5](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1750.5.&lawCode=BPC)
[^A8]: California Business & Professions Code §1752.4 — RDA duties and supervision levels, including the general-supervision baseline for restorative duties and the dentist's discretion under subdivision (d). [California Business & Professions Code §1752.4](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1752.4.&lawCode=BPC)
[^A9]: California Business & Professions Code §§1753–1753.6 — RDAEF licensure and duties, including direct-restoration authority for licensees on or after January 1, 2010. [California Business & Professions Code §§1753–1753.6](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=1753.5.&lawCode=BPC)
[^B1]: Dental Board of California — Registered Dental Assistant Combined Written and Law and Ethics Examination Outline (2023). [Dental Board of California](https://www.dbc.ca.gov/formspubs/rda_exam_outline.pdf)
[^C1]: Bird DL, Robinson DS. Modern Dental Assisting. Current edition, Elsevier. — clinical dental-assisting content for Areas 1–2 where no statute controls.

[^A22]: 16 CCR §§1085–1087 — Dental assisting duty regulations implementing the permitted-duties framework. [16 CCR §§1085–1087](https://govt.westlaw.com/calregs/)

[^B5]: Dental Board of California — Table of Dental Auxiliary Duties Delegable by Supervising Dentist. [Dental Board of California](https://www.dbc.ca.gov/formspubs/pub_permitted_duties.pdf)

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