Indications for use:

• Isolating lining for pulp protection in deciduous and permanent teeth;

• permanent fillings in deciduous teeth at stage of root resorption;

• long-lasting temporary fillings (1-2 months).

Mixing:

Artificial dentine (zinc-sulfate cement)

Composition:

• powder – dehydrated zinc sulfate (24%), kaolin (10%), zinc oxide (66%);

• liquid – distilled water.

Mixing is performed at rough surface of glass plate with metal spatula. Powder is added to water until complete absorption of water by powder and mixed. Mixed mass must be introduced into the cavity with smoother and condensed. It hardens during 2-3 minutes.

Amalgam

Typers of amalgam:

• silver amalgam;

• gold amalgam;

• copper amalgam.

• with spherical particles;

• with needle-like particles.

Composition of silver amalgam:

It is an alloy of several metals (silver - 65%, tin - 29%, copper – 6-20%, zinc – up to 1%) mixed with mercury.

Properties of amalgams depend on metals in an alloy. Silver cause mechanical strength, antimicrobial effect, amalgam expansion at hardening. Tin cause shrinkage, decreases strength, slows down process of amalgam hardening. Addition of copper to amalgam raises mechanical strength. Zinc is added into the structure of amalgam for protection from oxidation.

Advantages:

• high mechanical strength;

• stabile in oral fluids;

• can be polished.

Disadvantages:

• high heat conductivity;

• has no adhesion;

• factor of thermal expansion exceeds those of hard dental;

• shrinkage during hardening

• changes colour of a tooth;

• mercury vapor is toxic for medical personnel.

Indications for use:

• filling of classes I and II caries cavities in permanent teeth;

• filling of class V caries cavity in permanent molar;

• filling of classes I and II caries cavities in deciduous teeth.

Considerable influence on properties of an amalgam is rendered a way of manufacturing, the size of particles and their form. The amalgam that has small particles is stronger, gives smaller shrinkage, has homogeneous structure. Particles can have needle-like and spherical form. During amalgam creation 2 processes take place simultaneously - alloy dissolution in mercury and creation of new phases. Amalgam sawdust consists of two components: inter-metal combination Ag₃Sn (gamma - phase) and fusible mix - Ag₃Sn + Sn. More silver is in an alloy - more content Ag₃Sn, that is gamma - phase. In the course of creation of a firm amalgam, parts of Ag₃Sn and tin react with mercury, and the part of initial gamma - phase remains. Thus two new phases are created: gamma –1 and gamma –2 [Ag₂Hg₃ (gamma-1), Sn₈Hg (gamma-2)].

The matrix of hard amalgam is gamma - 1 (Ag₂Hg₃), and parts of gamma-phase Ag₃Sn interspersed in a matrix (filler). Other connections of gamma-2 phase (Cu₃Hg₄, Sn₇Hg₁₅) are placed in the matrix. Strength of amalgam increases, when the quantity of gamma-phases increases. Process of amalgam's hardening can be accompanied with shrinkage, and creation of new phases (gamma-1 and gamma-2).

Amalgams of new generation have no gamma-2 phase. Gamma–2 phase reduces hardness of filling and increase corrosion. Non-gamma-2 amalgam has bigger content of copper (up to 20%) that compete with tin for mercury.

Algorithm of developing a professional technique in vitro “Filling of class I-V cavities with amalgam” (on phantom)

№	Sequence of actions	Criteria of correct performance
1.	Put the isolating cavity liner of ZnP, GIC or ZnPCC.	Isolating layer covers cavity floor and walls up to the enamel-dentinal junction.
2.	Put the capsule with silver powder and mercury 1:1 into amalgamator. Mixing time is 15-60 sec. depending on the type of amalgam.	For mixing time check manufacturer’s instructions. Ready to use amalgam “crepitates” and does not crack when squeezed in fingers. Use gauze or rubber gloves to squeeze amalgam.
3.	Introduce the first portion of amalgam into the cavity with amalgam tregger right after it was mixed.	Filling process started in within a minute after the mixing. Amalgam is introduced with a little portion.
4.	First portion of amalgam is rubbed into cavity walls and floor with the rotating motions of special plugger.
5.	Fill the cavity in little portions. Thoroughly condense every portion with a special plugger. Start condensation from the center and move to the cavity walls.	Every portion is no more than 3-5 mm. Amalgam filling slightly overfills the cavity.
6.	Do the rough finishing of the supple amalgam. Form the occlusal surface of the filling. Take away the thin layer of amalgam that coats the enamel with an excavator.	Filling restores the anatomical shape of the tooth: occlusal and vestibular surface in cervical region. Thin layer of amalgam overlaps the enamel at the edge of the filling.
7.	Finishing and polishing of the filling is performed in the next visit (in 24 hours). Finishing is done with carborundum heads, abrasive disks and finires, polishing – with polires, polishing heads, soft brushes with polishing paste.	Constant water cooling of the filling during the finishing and polishing. The surface of the filling is smooth, mirror-shiny.