Glass ionomer cements (GIC) consist of two components - glass powder and copolymer acids. The powder of glass ionomer cement is thin crushed fluoro-aluminosilicate glass with the big maintenance of calcium and fluorine, and also with insignificant quantity of sodium and phosphates. It’s main components are silicon oxide (SiO2), aluminium oxide (Al2O3) and fluoride of calcium (CaF2). The structure of glass in small quantities includes also fluorides of sodium and aluminium, phosphates of calcium or aluminium. As polymer combinations nonsaturated polycarbonate acids are used: acrylic, itaconic and maleic. The liquid glass ionomer cement is 47,5 % (40-55 %) a water solution of copolymer of acrilyc and itaconic or acrilyc and maleic acids.
Forms of glass ionomer cements: water systems, waterless systems, hemihydrate systems.
Classification of glass ionomer cements: by applicability glass ionomer cements are divided into the following types: the I-st type - fixing (for fixing orthopedic designs); the 2-nd type - restorative for filling carious cavities; the 3-d type - lining (for liners).
By physico-mechanical properties: traditional, strengthened, hybrid. By the type of hardening: with the traditional mechanism of hardening (acid-basic reaction); the traditional and light mechanism of hardening; the traditional, light and chemical mechanism of hardening. By the chemical compound: traditional, argentiferous, hybrid, glass ionomers on the basis of strontium.
Positive properties: chemical adhesion to the tooth’s hard tissue; high biocompatibility (nontoxicity); anticariesgenic effect, radioopacity; appliance of thermal expansion coefficient of tooth’s hard tissue; low thermal conductivity; chemical adhesion to the majority of materials; rather low solubility in oral liquid.
Negative properties: crumbling; low stability to abrasion; insufficient aesthetic properties.
Indications for usage traditional glass ionomer cements: filling carious cavities of the I-st and III-d classes and caries of roots in permanent teeth, filling carious cavities of the I-st class that are not located in occlusal field: pits in permanents molars; filling carious cavities of the I-st and V-th classes in temporary teeth; treatment of caries of temporary teeth by an ART-technique; imposing liners in temporary and permanent teeth; extended temporary filling of permanent teeth; filling noncarious impairments of teeth hard tissue.
The amalgam is an alloy of mercury with one or several metals. Types of an amalgam: silver, copper, gold. The silver amalgam consists of an alloy of silver (65 %), tin (up to 29 %), copper (2-6 %) and zinc (up to 1 %), that mix up with mercury. Classification of amalgam: by the size and the form of particles of an alloy: the I-st type - particles have needle-like form (sawdust) and do not exceed 160 microns in the sizes; the II-nd type – finely dispersed particles of the spherical form in the sizes from 4 up to 40 microns; the III-d type - mixed, is formed by mixing powder of two previous types. The amalgam which has hardened, will consist from the following basic phases: particles of an alloy of silver and tin (Ag3Sn) - a gamma-phase; connections of silver and mercury (Ag2Hg3) - gamma - 1; connections of tin and mercury (Sn8Hg) - gamma - 2.
The positive properties of amalgam: high mechanical durability; plasticity; stability to oral liquid; ability for polishing.
Negative properties: high thermal conductivity; absence of adhesion; discrepancy of thermal expansion coefficient of tooth hard tissue; change of color of a tooth.
Indications for application of amalgam in practice of pediatric dentistry: filling carious cavities of the I-st and II-nd classes in permanent teeth; filling carious cavities of the V-th class in permanents molars; filling carious cavities of the I-st and II-nd classes in temporary teeth.
Algorithm of developing a professional technique “Filling of class I-V cavities with glass-ionomer cements” (on phantom)
| № | Sequence of actions | Criteria of correct performance |
| 1. | Apply the conditioner to the cavity walls for 10-30 sec., if included in the set. | Conditioner covers the cavity walls and floor. |
| 2. | Rinse with water for 10-20 sec. | No conditioner left in the cavity. |
| 3. | Dry the cavity for 10-20 sec. | Cavity is slightly wet. |
| Put the glass plate (smooth surface up) or a paper pad for mixing of the material on the table. | Glass plate is dry. | |
| 5. | Apply necessary amount of liquid on the pad. Hold the bottle high for the liquid to drop freely. | Consult the manual about the powder-liquid ratio, follow the instructions. |
| 6. | Shake the bottle with powder before opening. Use the measuring spoon (included) to measure the necessary amount of powder. Put the powder on the pad. | For restorative GIC powder: liquid ration is 3:1. |
| 7. | Divide the measured powder into 2 equal parts. | |
| 8. | First half quickly mix with the liquid for 10-20 sec. | Mass is homogenous. |
| 9. | Add the second half of the powder to the homogenous mass and mix for 20 sec. General mixing time is 30-40 sec. | Mass is homogenous, shiny, does not follow the spatula. |
| 10. | Introduce the material into the cavity in a whole. Condense it. Modeling of the filling should not exceed 1 min. | Filling material fills the whole cavity and is adjunct to the cavity walls. |
| 11. | Primary correction of the filling is done after the setting time (4-5 min.) with carborundum stones and flexible abrasive discs. | Surface of the filling is smooth, restores the anatomical shape of the tooth (occlusal or vestibular surface in the cervical region). |
| 12. | If the isolating varnish is included in the set, apply it to the filling and blow with air | Filling is glossy. |
| Finishing and polishing is done with diamond heads, flexible disks, rubber cups with polishing paste on the next visit (after 24 hours) after the final setting of the filling. | Filling is smooth. | |
| Coat the filling with a varnish for a second time, blow with air. | Filling is glossy. |
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. |
| 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. | |
| 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. | |
| First portion of amalgam is rubbed into cavity walls and floor with the rotating motions of special plugger. | ||
| 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. |
| 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. |
Control questions:
1. To understand techniques of filling on phantoms carious cavities of the I-st and V-th classes in temporary and permanent teeth with dental cements: glass-ionomer, zinc-phosphatic and polycarboxylate.
2. To understand fillings techniques of carious cavities of the I-st and V-th classes in temporary and permanent teeth with amalgam on phantoms.
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