MINISTRY of PUBLICHEALTH ofUKRAINE
VINNITSYANATIONALMEDICALUNIVERSITY
by N.I.Pirogov
It is "confirmed"
on a methodical meeting of
department of pediatric dentistry
head-chair
doc. Filimonov Yu.V.______
"______"______in 20
Methodical recommendation for 2d year students
of dental faculty
Educational discipline / Propedeutics of pediatric dentistryModule ¹ / 1
Rich in content module ¹ / 1
Topic / Dentistry cements. The technique of carious cavity filling of deciduous and permanent teeth.
Course / 2
Faculty / Dental
Vinnitsya 2010
- Actuality of theme: A specific of terms is cavities of mouth, stopping functions in which, the anatomicfeatures of temporal and permanent teeth explain absence to this time of material which would answer all of requirements. For achievement of optimum clinical effect at stopping of teeth for children and for adults it is very important to have material which next to all owned other properties and aesthetically beautiful peculiarities a doctor. In addition had sufficient durability and beautiful operating properties.
- Concrete aims: to learn classification, composition basic properties of Dentistry cements. To learn to differentiate the systems of different generations, know their composition, properties and method of the use.To know instruments and materials for eventual treatment of stoppings.
Names of previous disciplines / Skills are got
Normal anatomy / Able defirintiation temporal and permanent teeth. To know the anatomic features of temporal teeth depending on the stage of development of tooth.
Therapeutic stomatology / To know basic methods and principles of preparing of teeth in grown man age. Oriented in the choice of instruments for realization of that or other manipulation. Able to pick up stopping material depending on a situation.
Orthopaedic stomatology / Oriented in materials which are utillized in the clinic of orthopaedic stomatology.
3. Base knowledges, abilities, habits which are necessary for study the topic.
- To know instruments for preparation of stopping material and auxiliary facilities for stopping of carious cavities.
- To know instruments and materials for eventual treatment of stoppings.
- To write classification of Dentistry cements.
- To transfer basic positive and negative properties of Dentistry cements of the chemical and light hardening.
- To write the stages ofstopping ofcarious cavityDentistry cementsof the chemical.
4.1. List of basic terms, parameters, descriptions which a student must learn at preparation to lesson:
Term / DeterminationDentistry cements / Contemporary filling materials, which have high physic-chemical and esthetic properties
Chemical polimerization / Material polimerization is provided as result of catalic system, which is present in composite composition
Light curing polimerizetion). / Polimerizetion is provided under the influence of light with wave length 450 nm
4.2. Theoretical questions for lesson:
1.To transfer and describe the types dentistry cements.
2.To know the types of dental handpieces, their structure and function.
3.To know the types of dental drills and others dental instruments for filling.
4.Toknow the types of dental accessories for filling.
4.3.Practical taskswhich are executed on the lesson:
1. To know the classification of cements.
2.To classify dental handpieces depending dental drills which are evidently demonstrated teachers?
3. To know the stage filling of dentistry cements.
5. Plan and organizational structure of lesson from discipline.
¹ / Stages / Distributing of time / Types of control / Facilities of education1. / Preparatory stage / 15 min / practical tasks, situatioonal tasks, verbal questioning, are after the standardized lists of questions. / textbooks, manuals, methodical recommendations.
1.11.1 / OtТhe Organizational questions.
1.2 / Forming of motivation.
1.3 / Control
initial level of knoweledge .
2. / Basic stage. / 55 min
3. / Final stage / 20 min / tests tasks
3.1. / Control of final level of preparation.
3.2. / General estimation of educational activity of student.
3.3 / Informing of students is about the topic of next lesson.
Content of topic:
Cements are generally hard, brittle materials that are formed when a powdered oxide or glass is mixed with a liquid. When mixed to a cementing consistency, dental cements are used to retain restorations such as metal or ceramic crowns and esthetic inlays, onlays, and veneers. When mixed to a thicker consistency, some cements are used as temporary filling materials or to provide thermal insulation and mechanical support to teeth restored with other materials, such as amalgam, composites.
The classification of cements:
I) Mineral cements (on the basis of a phosphoric acid):
1. Zinc phosphate;
2. Silicate;
3. Silico-phospate.
II) Polymeric cements (on the basis of polyacrylic or other organic acid):
1. Polycarboxylate
2. Glass Ionomer.
I. The mineral cements are one of oldest filling material. Structure of powder of all these cements includes oxide of Zincum, magnesium, calcium, silicon, aluminium in different correlation. The liquid is a mix of ortho - para- and metaphosphoric acids with zinc phosphates, magnesium, aluminium. Depending on an elemental composition the mineral cements divide on Zinc- phosphate, Silicate and Silico-phosphate.
Zinc- phosphatecements. The using of Zinc - phosphate cements today is limited. It is used basically as insulating liner. Such properties, as a poor mechanical strength and dissolubility in a oral liquid make them practically unsuitable for usage as permanent filling materials.
The exceptions may be only in following cases:
- at filling ofdeciduous teeth for 1-1,5 years to their replacement;
- at filling of teeth, which will be covered by crown.
Composition and reaction. The zinc phosphate cement powder is primarily zinc oxide with additions of magnesium oxide and pigments. The liquid is a solution of phosphoric acid in water buffered by aluminium and zinc ions to help slow the setting reaction during mixing. A chemical reaction begins when the cement powder is incorporated into the liquid. The surface of the alkaline powder is dissolved by the acidic liquid, resulting in an exothermic reaction. The cement is mixed in such a way as to minimize the temperature rise from the heat given off. The set cement is essentially a hydrated amorphous network of zinc phosphate that surrounds incompletely dissolved particles of zinc oxide. The cement is very porous.
Setting of zinc phosphate cement is affected by time and temperature. Cooling the mixing slab increases the working time. The cement normally sets in the mouth within 5 to 9 minutes from the start of mixing. Factors such as higher powder-liquid ratio, faster incorporation of powder into the liquid, and a warmer slab cause the cement to set faster than it would. Cementation should be completed promptly after mixing; delays can result in larger film thicknesses and insufficient seating of restorations.
Properties. Some important properties of zinc phosphate cement include fast setting time, good mechanical properties, low film thickness, low solubility, and low acidity of the set cement. The compressive strength ofzinc phosphate cement is similar (tab.1) to that of glass ionomer cement. Properties of elasticity of zinc phosphate cement can be adversely affected by a low powder-to-liquid ratio, improper mixing, and premature exposure to oral fluids (tab.2). The strength develops rapidly, with two thirds of final strength being reached in 1 hour.
The film thickness (25 m maximum) and solubility in water (0,2 % maximum weight loss after 24 hours) are within clinically acceptable limits. The pH of zinc phosphate cement is initially low (pH 4,2) but increases to nearly neutral after 48 hours. The initial acidity may have a deleterious effect on the pulp, particularly on one that is traumatized already. Pulpal protection is recommended. The retention ofzinc phosphate cementis caused by mechanical interlocking with the surfaces of the tooth and restoration.
Manipulation. Shake the bottle of powder gently and swirl the bottle of liquid before dispensing of contents. Dispense the cement powder with a scoop supplied by the manufacturer. Divide the powder in one corner of the glass slab into four to six portions, depending on the product. Dispense the correct amount of liquid, given by drops as directed in the instructions, to an area of the slab away from the powder. Add the powder to the liquid in portions at 15-second intervals for a total mixing time of 60 to 120 seconds, depending on the product. Mix the cement over a large area of the slab with broad strokes of a flexible metal spatula. Test the consistency of the cement before adding the last portion of powder. Only part of that portion of powder may be necessary to reach the desired consistency. The cementing consistency strings about an inch above the slab.
The examples: "Natrii phosphas - cement", "Uniphas", "Adgesor" (Dental Spofa), Poscal (Voco), Tenet (Vіvadent). Cements, that contain in the structure argentum: "Argіl" (Dental Spofa), " Phoscin bactericidal " (Rainbow - Russia). Cements with cuprums: " Harvard Kupferzement " (Harvard), " Kron-Fіx N " (Merz); with the contents of bismuth: "Visphat cement ", "Dioxyvisphat".
Silicatecements. The silicate cements represent a system "powder - liquid". A powder is the finely granulated aluminosilicate glass (silicon oxides, aluminium, calcite, fluorines natrium - up to 15 %). A liquid is a mix of phosphoric acids.
Positive properties:
- satisfactory aesthetic qualities;
- coefficient of thermal expansion such as tissues of teeth;
- a simplicity of usage;
- availability and low-level price;
Negative properties:
- the high toxicity requires insulating of the pulp;
- a poor mechanical strength;
- dissolubility in the oral liquid;
- inadhesion to tissues of teeth;
The examples of silicate cements: "Silicin" (Russia), "Alumodent", "Frіtex" (Dental Spofa), Sіlіcap (Vіvadent).
Silico-phosphate cements. The silico-phosphate cements are the mix of a powder of Zinc - phosphate and silicate cement. The powder contains approximately 80 % silicate and 20 % of phosphate cement. A liquid is mix of phosphoric acids.
Positive properties
- the mechanical strength is morethan “Silicin” and Natrii phosphases - cements,
- the irritant influencing on a pulp is smaller, than in “Silicine”, (at the expense of kept in repair oxide of Zincum);
- the adhesion to tissues of teeth is best to compare to silicate cements;
- a simplicity of usage;
- availabilityand low-level price.
Negative properties:
- unsatisfactory aesthetic qualities;
- an inadequate strength;
- poor stability in an oral cavity;
- toxicity for a pulp of teeth (it is necessaryto use insulating of the pulp).
There are some "children" silico-phosphate cements, in which ones the powder consists of 60 % silicate and 40 % of Zinc - phosphate cement. At the expense of heightened kept in repair oxide of Zinc there is a rather fast decontamination of a phosphoric acid, and the irritant influence of the cement on a pulp practically fails. Them will use at sealing deciduous teeth. The examples of “children” cements: “Lactodont” (Russia), "Іnfantіd" (Dental Spofa).
The examples of silico-phosphate cements: "Silidont-2" (Russia), " Unіversal cement " (SPAD), "TransLіt" (Merz), "StaіnZement" (Drala).
II.
Zinc Polycarboxylate Cements.
Composition and reaction. Zinc polycarboxilate cements are supplied usually as a powder and a liquid. The powder is mainly zinc oxide, and the liquid is a viscous solution of polyacrylic acid in water. One product (Tylok Plus) is supplied as a powder to be mixed with tap water. Its powder consists of zinc oxide coated with solid polyacrylic acid.
The zinc oxide and the polyacrylic acid react to form a zinc polyacrylate that surrounds the partially reacted zinc oxide powder particles. The reaction is accelerated by heat.
Properties. The important properties of zinc polycarboxilate cements are moderate viscosity, moderate strength, bonding to enamel, and being mildly acidic. Mixed polycarboxilate cement appears to be too viscous (thick), but it flows readily when applied to the surfaces to be cemented. The compressive strength of polycarboxilate cement is less that of glass ionomer cement.
Zinc polycarboxilate cements are slightly acidic (low pH) when first mixed, but the acid is weakly dissociated.
Manipulation. Shake the powder bottle gently. Dispense the powder with a scoop onto a disposable paper pad or a glass slab, which can be cooled to permit a longer working time. Dispense the viscous liquid from the dropper bottle in uniform drops. Durelon liquid is supplied in calibrated syringe to improve the accuracy of dispencing the liquid.
Add about 90 % of the powder immediately to the liquid and mix for 30 to 60 seconds, depending on the product. Add the remainder of the powder to adjust the consistency. Mix over a small area of the mixing surface with a stiff spatula. The proper consistency is creamy. Use the cement immediately because the working time is short (about 3 minutes after mixing at 220 C). The cement is no longer usable when it loses its luster and becomes stringy or starts to “cobweb”.
The examples ofpolycarboxilate cements: "Carboxylate Cement» (Heraeus/Kulzer), "Durelon" (3 M ESPE), "Carboco" (Voco), Aqualox (Voco).
Materials are for self-control:
1. Which of the composites with the following fillers may be radique?
a) quartz
b) lithium aluminium silicate
c) colloidal silica
*d) barium glass
2. When using dental cements?
1) For obturating root canal
2) For filling caress cavity
3) For temporary restoration
4) For base, liners
5) Sealants
3. Dental cements classified according to the matrix-forming species:
1) Phosphate bonded
2) Phenolate bonded
3) Polycarboxylate bonded
4) Polymethacrylate bonded
5) Eugenolbonded
Literature.
Basic:
1.Lectures which are read on the department of pediatric dentistry.
2. Л. О. Хоменко, О. І. Остапко, О. Ф. Конанович, та ін. Терапевтична стоматологія дитячого віку.- Видавництво "Книга плюс", 2007 р.
3. Pediatric dentistry /Ed. R.R.Welbury.- Oxford, 1997 – 584p.
Additional:
1.Боровський Г.В., Барішева Ю.Д., Максимов К. М. и др. Терапевтическая стоматология. — М.: Медицина, 1997.
2. PinkhamJ.R. Pediatricdentistry. – 2nded.- W.B. Sounders Company. – 1994.- 647 p.