Restorative - Outcome 8

Question 1

Calcium Hydroxite Liner

Answer 1

A dental liner is a thin layer of material placed at the deepest portion of the cavity preparation, to provide pulpal protection or dentinal regeneration (repair). The purpose is to protect the pulpal tissue from irritation caused by physical, mechanical, chemical, and biologic elements. The health and condition of the tooth being restored determines which liner they may use. As an RDA you may be directed to place the liner by the dentist.

Question 2

Polycarboxylate Base

Answer 2

If a cavity preparation is deep (close to the pulp), the dentist may ask the assistant to prepare and place a cement base onto the floor of the cavity preparation. The base material should resemble a putty-like consistency as it provides a buffer or layer between the pulp and the restoration.

Question 3

The three terms that are associated with the purpose of a base are as follows:

Answer 3

1. Protective Base – prevent post-operative sensitivity
2. Insulating Base – prevent thermal shock
3. Sedative Base – soothes the pulp when the pulp has been traumatized or has been damaged by decay.

Question 4

Glass Ionomer Liner

Answer 4

Glass Ionomer cement is one of the most commonly used types of cement in dentistry. There are three types that are used; Type I, Type II, and Type III. This course will focus on Type III Glass Ionomer, which is used for the purpose of a dental liner in cavity preparation. Its purpose in the cavity preparation is to help prevent post-operative sensitivity by bonding to dentin and creating a seal against microleakage.

Question 5

Different types of Glass Ionomers

Answer 5

Glass Ionomer liners are supplied in ‘self-cured’ and ‘light-cured’ versions. Powder and liquid is the most common method of dispensing. See manufacturer’s instructions for dispensing ratios, as well as for accurate curing times for the light-cured versions.

Question 6

Curing times for glass ionomers

Answer 6

Typical curing times for glass ionomer liners are between 20 and 30 seconds based on manufacturers’ instructions of the brand you are using.

Question 7

Advantages of using glass ionomer as a treatment liner:

Answer 7

Bonds to the tooth structure
Releases fluoride over time and inhibits recurrent caries
Causes less trauma or shock to the pulpal tissue

Question 8

Disadvantages of using glass ionomer as a treatment liner:

Answer 8

May require the additional curing step
Light cured glass ionomers may be difficult to set in hard to reach preparations due to limited access of the curing light

Question 9

Use of a Calcium Hydroxide Liner

Answer 9

If a cavity preparation involves the removal of dentinal decay, the dentist may decide to place calcium hydroxide on the pulpal floor of the cavity preparation to stimulate the growth of secondary dentin. The material will penetrate through the thin layer of dentin and stimulate the pulp to produce reparative dentin, and in turn create a thicker layer of dentin between the floor of the preparation and the pulp. This will assist in preventing sensitivity and/or pulp trauma. It can also protect the pulp from chemical irritation through its sealing ability and is compatible with all types of restorative materials. Liners are supplied either as a two-paste system or as a light-cured material.

Question 10

Two types of Calcium Hydroxide liners

Answer 10

Liners are supplied either as a two-paste system or as a light-cured material. The liner is placed in the deepest dentin surface of the preparation, using a liner applicator. This material is not to be placed on enamel or in retentive grooves of the preparation (Robinson, 2024).

Question 11

Polycarboxylate Base

Answer 11

Polycarboxylate cement is used for multiple purposes. It may be utilized as a luting ( cement) material for cementing appliances and prosthesis to teeth, as a sedative base in deep cavity preparations and for an intermediate restoration. Restorative 1 will focus on the use of polycarboxylate cement in the form of a base.

Question 12

Polycarboxylate types of cement are available in two forms:

Answer 12

Aqueous polycarboxylate cement includes water in its components.
Anhydrous polycarboxylate cement contains no water; it is supplied only as a powder, so distilled water is used for mixing.

Question 13

Advantages of Polycarboxylate Cement

Answer 13

Polycarboxylate cement bonds to tooth structure preventing microleakage from occurring
It is less acidic than zinc phosphate cement and therefore less irritating to the pulp
Stannous fluoride is in the cement, so it has anti-cariogenic properties

Question 14

Disadvantages of Polycarboxylate Cement

Answer 14

Very short working time
The adhesive qualities are lost when mixing time is prolonged