RDA Preventive Dentistry and Patient Education

Question 1

Coronal polishing with a rubber cup and prophy paste is intended to remove:

Accepted Answer

Extrinsic stains and soft deposits (plaque biofilm)

Answer

Coronal polishing removes extrinsic (surface) stains and soft deposits such as plaque biofilm from the clinical crowns of teeth. It does NOT remove calculus (tartar), which requires scaling instruments used by the hygienist or dentist. Intrinsic stains are within the tooth structure and cannot be removed by polishing.

Question 2

Which type of fluoride application requires the patient to refrain from eating or drinking for 30 minutes after application?

Accepted Answer

Acidulated phosphate fluoride (APF) gel in trays

Answer

APF gel applied in trays requires a post-treatment waiting period of 30 minutes to allow fluoride uptake into enamel before food or drink dilutes or removes it. Fluoride varnish, by contrast, can be applied and the patient may eat soft foods almost immediately because the varnish adheres to the tooth surface.

Question 3

A pit-and-fissure sealant is placed on posterior teeth primarily to:

Accepted Answer

Seal the deep occlusal grooves that trap plaque and are prone to decay

Answer

Sealants physically block the deep pits and fissures on occlusal surfaces of molars and premolars where toothbrush bristles cannot reach. This prevents bacteria and food from accumulating in these high-risk sites. Sealants complement, but do not replace, fluoride therapy.

Question 4

When instructing a patient on the Bass toothbrushing technique, the dental assistant should direct the patient to angle the brush bristles at approximately:

Accepted Answer

45 degrees toward the gingival margin

Answer

The Bass technique places the bristles at a 45-degree angle to the gingival margin so they penetrate slightly into the gingival sulcus and disrupt subgingival plaque. This makes it effective for patients with gingivitis or periodontal disease. The bristles are then vibrated with short back-and-forth strokes.

Question 5

Which dietary carbohydrate is considered the most cariogenic (decay-causing) because oral bacteria ferment it most readily?

Accepted Answer

Sucrose (table sugar)

Answer

Sucrose is the most cariogenic carbohydrate. Streptococcus mutans uses sucrose to produce both lactic acid (which demineralizes enamel) and the glucan matrix that helps biofilm adhere to teeth. Sugar alcohols like sorbitol are not fermented by cariogenic bacteria and are considered non-cariogenic.

(RDA) Registered Dental Assistant Practice Test

(RDA) Registered Dental Assistant Practice Test

RDA Preventive Dentistry and Patient Education