Auxilary Materials

Question 1

DENTURE ADHESIVES

Answer 1

To enhance:
•Stability
•Bite force
•Sense of security, especially for musicians and
public speakers

To provide retention:
•For those with dry mouth
•For those taking cold medications
•For those with neurological disabilities including strokes
•For the elderly

Question 2

CONTRAINDICATIONS FOR DENTURE ADHESIVES

Answer 2

ill-fitting or poorly constructed dentures
•Loose feeling dentures
•Discomfort due to sores
•When the frequency and amount of adhesive increase
•Allergy to the adhesive’s ingredients

Question 3

SURFACE BONDING

Answer 3

If a fluid travels across a solid surface then adhesion is present at the interface.
•Surface wettability may be measured by a number of techniques and various behaviours may be observed.
•The success with which the surface is wetted by a particular agent is measured by the CONTACT ANGLE
•A contact angle of 0 degrees implies complete wetting, termed “spreading”.

Question 4

SURFACE PRIMING

Answer 4

•Treatment of a surface which increases its critical surface energy
•Without considering the addition of bulk material to a surface (ie effectively replacing one surface with another)
•two general approaches are possible in dentistry:

1. Physical/Physico-chemical priming
2. Chemical priming

Question 5

CHEMICAL PRIMER

Answer 5

•Some may be chemically reactive towards the bonding agent
•the use of a particular surface priming technique may also introduce micro-mechanical features into the substrate (eg acid-etching of dental enamel).
• Descriptions such as ‘conditioner’, ‘primer’ and ‘coupling agent’ are found in the dental literature.

Question 6

GRIT-BLASTING

Answer 6

Abrasion of bonding surfaces with a bur is clearly arbitrary and non-consistent.
A treatment technique that have relevance to a number of surfaces is air abrasion or grit-blasting.
e.g dental casting alloys, composite resins, ceramics and dental hard tissue.

Question 7

ULTRASONIC CLEANSING

Answer 7

Ultrasonic cleansing involves a liquid or solution medium which is exposed to a suitable
vibratory regime.
•energy generated within the liquid, or solution, generates cavitational action which assists in the removal of surface contaminants.
• Inter alia, the method has been applied to the pre-cleaning of endodontic instruments, implant devices and contaminant removal from the surfaces of complete dentures.

Question 8

ELECTROCHEMICAL ETCHING

Answer 8

Electrochemical preparation of a polycrystalline dental casting is possible using
electrochemical etching and a suitable current density.

The effect is the preferential dissolution of inter - dendritic material, where the grains feature a cored microstructure, and micromechanical retention can be achieved by this mechanism

Question 9

GLOW-DISCHARGE TREATMENT

Answer 9

Glow-discharge treatment (GDT) functions through the removal of surface material by the
kinetic action of high-velocity gaseous ions (usually Ar) in an electric field.

Main interest has been the cleansing of metal implant surfaces but, as low temperatures can be utilised, other materials may also be treated, including dielectrics.

Question 10

LASER & ELECTRON-BEAM TREATMENT

Answer 10

Laser and electron-beam thermal treatments involve surface localised heating & quenching,
which may invoke interesting microstructural changes in the case of metals.
Ion implantation is a technique relevant to the microelectronics industry for the implantation of
charge carriers into semi-conductor materials. The ‘dopant’ ions may implanted into the
surface to a depth of about 5 microns

Question 11

SILANE COATING

Answer 11

Silane treatment, or ‘Silicoating’ results in the generation of a SiOx layer on the metal
surface
- improved wettability
- and the possibility of chemical bonding with a
luting resin via a silane coupling agent.

Question 12

CHEMICAL PRIMING

Answer 12

involve attempts at surface cleansing, or degreasing
(sometimes referred to as ‘conditioning’), but more usually involves treating the surface
with a chemical protocol

Question 13

TYPES OF DENTAL CEMENT

Answer 13

Dental cements are classified by the type of matrix present in the set material, rather than application like the adhesives, thus:

1. Phenolate
2. Phosphate
3. Polyacrylate-type
4. Resin (ie polymeric)

Question 14

LUTING CEMENT

Answer 14

Applied as a thin (ca 25 micron) layer to bond a
restoration to the tooth or to another restorative
Material.

Question 15

CAVITY LINING MATERIAL

Answer 15

Apply in a thin layer to seal the surface of dentine, in some cases to promote bonding between the tooth material & the filling.
usually volatile solutions which set to a thin layer through the loss of solvent
(eg ether, ethanol, methylene chloride).

0

Question 16

PHENOLATE CEMENTS

Answer 16

Two types of material have traditionally been used under certain filling materials
- CALCIUM HYDROXIDE
forms an anti-bacterial environment and suitable conditions for the formation of secondary dentine,
- ZINC OXIDE/EUGENOL (ZOE)
features eugenol which is an obtundent (a drug which lessens pain).

Question 17

ZINC OXIDE/EUGENOL (ZOE

Answer 17

EUGENOL is a very weak organic acid, of the phenol type
•It has an OBTUNDENT (desensitising) effect on dentine
•The material is a colourless liquid when pure, but thickens and yellows on exposure to air.
•Recent research has shown that eugenol can complex with serum albumin and lipids in the dentinal tubules this mechanism probably explains the relevant therapeutic action.

Question 18

CALCIUM HYDROXIDE

Answer 18

A slurry of calcium hydroxide, in sterile water, sealed in a carious lesion
•established anti-bacterial effect
•may promote some re-mineralisation of the affected dentine
•a useful agent in circumstances where all of the carious dentine cannot be removed prior to the insertion of a filling.
•in favourable cases, the resultant formation of secondary dentine may close a penetration.

Question 19

ZINC PHOSPHATE CEMENT

Answer 19

developed from the acid- base reaction of ZnO with a suitably formulated aqueous solution of phosphoric acid.
•The cement incorporates unreacted ZnO in a matrix of amorphous reaction products
•Has a high compressive strength
•the use of phosphoric acid allows the acid-etching of enamel and, possibly, of the restoration itself to enhance mechanical retention.

Question 20

POLYCARBOXYLATE CEMENTS

Answer 20

A new cement was claimed to feature
• compressive strength of the zinc phosphate materials.
•adhesion both to enamel and dentine,
•reduced marginal leakage
•the material was also envisaged as a cavity sealing agent and as an anti-cariogenic coating for enamel.
•material adhered to metals or alloys which featured a stable oxide layer on the surface (eg stainless steel).

Question 21

GLASS-IONOMER CEMENTS (POLYALKENOATE CEMENTS)

Answer 21

Appropriately formulated glass-ionomer materials are now used for a variety of applications, and a general classification is:

●Type 1: Luting materials
●Type 2: Restorative materials
●Type 3: Fast-setting cavity lining & fissure sealing materials