Question 1

The size, shape, and porosity of the gypsum particle determine the amount of water required to mix the product, particles that are large and vary in shape require the least amount of water when mixing.

A) The first statement is true, and the second statement is false.
B) The first statement is false, and the second statement is true.
C) Both statements are true.
D) Both statements are false.

Accepted Answer

Size, shape, and porosity of the gypsum particles determine the amount of water required to mix the product. Particles that are large and irregular require the most water when mixing.

Question 2

Increasing the amount of water used to mix stone will result in:&#10;A) decreases in setting time.&#10;B) dies that can be used in constructing crowns.&#10;C) a weaker model.&#10;D) a grainy cast.

Accepted Answer

Too much water increases setting time and decreases strength. Dies used in constructing crowns need the most strength. Too little water results in a cast with a grainy appearance.

Question 3

may lose water due to imbibition.&#10;A) 1, 2, 3, 4&#10;B) 1, 2, 4&#10;C) 1, 2&#10;D) 1

Accepted Answer

Because hydrocolloid is in a water suspension, the product is hydrophilic, meaning "loves water." These materials absorb water after their final set and are beneficial in impression taking because they are compatible with saliva and blood. Hydrophilic materials do not need a dry environment; they are well suited for a wet field. The correct term for loss of water is syneresis.

Question 4

Silicone alginate-alternative impression materials are especially helpful when:&#10;A) setting time is a concern.&#10;B) elasticity is a concern.&#10;C) dimensional stability is a concern.&#10;D) multiple molds may be needed.&#10;E) Both c and d are correct.

Accepted Answer

Silicone alginate-alternative impression materials have the dimensional stability of polysiloxane impression materials enabling re-pouring of models. Setting time is not a concern. Elasticity is the same as alginate.

Question 5

The dental hygienist suggested a preliminary diagnosis of night-time clenching/grinding. This diagnosis was based on all of the following factors except one. Which is the one exception?&#10;A) Pain in her jaw upon waking&#10;B) Significant bilateral linea alba&#10;C) Wear facets&#10;D) Anterior crowding

Accepted Answer

Anterior crowding was not a factor that contributed to the diagnosis. Pain in the patient's jaw upon waking, significant bilateral linea alba, and wear facets were factors in the diagnosis.

Question 6

Disinfecting of impressions:&#10;A) protects the patient from surface bacteria.&#10;B) must be completed after the impression is poured.&#10;C) is done only with impressions for patients with known infectious diseases.&#10;D) is completed after the impression is rinsed with water.

Accepted Answer

Impressions should be rinsed first with water to remove saliva, blood, and debris. Impressions are contaminated with the client's bacteria. Impressions are disinfected before pouring to prevent contamination of the cast. Dental impressions are considered contaminated and must be disinfected before handing in the office laboratory or sent to a commercial laboratory.

Question 7

A rope of utility or beading wax may be placed on the periphery of the stock tray to:&#10;A) lengthen the tray.&#10;B) help direct the impression materials into a high palatal vault.&#10;C) prevent material from flowing out of the tray.&#10;D) do all of the above.

Accepted Answer

If necessary, adapt the tray borders with utility (beading) wax to extend into the depth of the vestibule or extend the posterior length of the tray. To help prevent material from flowing out of the tray, place a wax dam on the posterior border of the maxillary tray to help contain the material.

Question 8

All of the following are techniques used to minimize the gag reflex during impression taking except one. Which is the one exception?&#10;A) Seat the client upright.&#10;B) Use as small a tray as possible.&#10;C) Seat the tray from the posterior to the anterior.&#10;D) Instruct the client to breathe through their nose.

Accepted Answer

Avoid using too small a tray, the material will flow out of the confines of a tray that is too small to accommodate the needs of the arch. Seat client upright. During insertion of a tray, instruct the client to bend their head forward with the chin tilting down. Seat maxillary tray from posterior to anterior to direct the flow of the impression material anteriorly away from the soft palate. Instruct clients to breathe slowly and deeply through the nose, to point toes, and/or to pinch the skin between the index finger and thumb.

Question 9

From each symptom select the most closely linked appropriate custom-made oral appliance.&#10;A) Snore guard&#10;B) Oral surgical stent&#10;C) Periodontal splint&#10;D) Aligners&#10;E) Night guard&#10;F) Mouthguard&#10;G) Whitening tray&#10;1. Tooth whitening&#10;2) Protection from health risks&#10;3) Bruxism&#10;4) Stabilization of mobile teeth&#10;5) Treatment of sleep apnea&#10;6) Orthodontic treatment&#10;7) Implant placement

Accepted Answer

The answer of From each symptom select the most closely...

Question 10

The setting time of a mix of dental stone ends when the:&#10;A) exothermic reaction is complete.&#10;B) stone no longer flows.&#10;C) model can be separated from the impression.&#10;D) material is the consistency of sour cream.

Accepted Answer

Final setting time occurs after the exothermic reaction (a chemical change accompanied by the liberation of heat) and the final product can no longer be manipulated without fracture. Working time ends when the stone no longer flows. If the model is separated from the impression before the final set, the final product may be fractured. When the material is properly mixed it is the consistency of sour cream.

Question 11

Preliminary impressions were taken of Patty's arches and study casts constructed. These study casts may be used for:&#10;A) documenting the client's dental arches as part of her permanent record.&#10;B) enhancing the client's education as a visual aid.&#10;C) constructing necessary custom-made oral appliances.&#10;D) all of the above.

Accepted Answer

The answer of Preliminary impressions were taken of Patty's arches...

Question 12

Orthodontic aligners were recommended to remedy her:&#10;A) parafunctional occlusal forces.&#10;B) orthodontic relapse.&#10;C) moderate BOP.&#10;D) recession.

Accepted Answer

The answer of Orthodontic aligners were recommended to remedy her:&#10;A)...

Question 13

Alginate impression materials may be separated from the stone casts after:&#10;A) the material no longer flows.&#10;B) 45 to 60 minutes.&#10;C) the material is in a semihard mass.&#10;D) the initial set.

Accepted Answer

The answer of Alginate impression materials may be separated from...

Question 14

Removable oral appliances are trays or devices used for a variety of dental procedures; these appliances are used for the delivery of materials and protection and movement of the teeth.&#10;A) The first statement is true, and the second statement is false.&#10;B) The first statement is false, and the second statement is true.&#10;C) Both statements are true.&#10;D) Both statements are false.

Accepted Answer

The answer of Removable oral appliances are trays or devices...

Question 15

A nightguard was recommended to mediate her:&#10;A) parafunctional occlusal forces.&#10;B) orthodontic relapse.&#10;C) moderate BOP.&#10;D) recession.

Accepted Answer

The answer of A nightguard was recommended to mediate her:&#10;A)...

Question 16

The best factor in controlling the setting time of alginate impression materials is the:&#10;A) temperature of the water.&#10;B) water-powder ratio.&#10;C) length of spatulation.&#10;D) All of the above are factors.

Accepted Answer

The answer of The best factor in controlling the setting...

Deck 37: Impressions, Study Casts, and Oral Appliances