CLINICAL AND LABORATORY PROCEDURES
- Dental preparation and temporalization.
- Taking of definitive impression.
- Elaboration of work models cast type IV-V plaster. mounting.
- Preparation of the wax pattern.
- Coating of the wax pattern.
- Tests of only metal structures, only ceramics, metal-ceramics. Cementing of the restoration, follow-up.
ODONTOLOGICAL USE WAXES
Natural and synthetic waxes.
- Fatty acids.
- Natural and synthetic resins.
- Pigments of various types.
CLASSIFICATION OF WAXES
According to its origin:
- Natural and synthetic.
According to its chemical composition:
- Hydrocarbons and esters.
According to its use:
- Casting waxes.
- Prefabricated shapes.
- Base waxes.
- Processing waxes.
- Waxes for prints and records.
CLASSIFICATION OF WAXES BY THEIR ORIGIN
NATURALS : Complex combinations of relatively high molecular weight organic compounds.
- MINERAL ORIGIN:
- Main hydrocarbon component of 17 to 44 carbon atoms.
- Odd or even chains.
- Paraffin, Microcrystalline, Cerezina, Montana, Ozoquerita, Barnsdahl.
- VEGETAL ORIGIN:
- They have hydrocarbons which are saturated alkanes with 19 to 31 carbon atoms always in odd numbers.
- Carnauba, candelilla, Japanese wax, uricuri, cocoa butter.
- ANIMAL ORIGIN:
- Beeswax, spermaceti
- Beeswax esters plus saturated and unsaturated hydrocarbons and organic acids of high molecular weight.
- Modifies the properties of paraffin.
- Main component of sticky wax.
- Vegetable and animal waxes contain a considerable amount of esters, also acids, alcohols, hydrocarbons and resins.
|PARAFFIN||40 – 70 ºC|
|MICROCRYSTALLINE||60 – 91 ºC|
|MONTANA||72 – 92 ºC|
|BARNSDAHL||70 – 74 ºC|
|CARNAUBA||84 – 91 ºC|
|URICURI||79 – 84 ºC|
|CANDELILLA||68 – 74 ºC|
|BEE WAX||63 – 70 ºC|
USE OF NATURAL WAXES
- INCREASE INTERVAL OF MELTING TEMPERATURE
- Montana, ceresin, carnauba, uricuri, barnsdahl, candelilla.
- Carnauba, Montana, Uricuri, Barnsdahl.
- Japan wax, cocoa butter are fats.
- Japan wax + paraffin = Improves adhesiveness.
- Cocoa Butter = Hydrate soft tissues.
- Complex organic compounds of diverse chemical composition.
- They are very refined.
- They do not contain the frequent contamination of natural waxes.
- They melt between 100ºC-105ºC
- Polyethylene waxes, polyoxyethylene glycol
- Hydrogenated, halogenated hydrocarbon waxes.
- They work as plasticizers.
OTHER WAX COMPOUNDS
- GUM: Viscous and amorphous exudates of plants and animals.
- They contain Carbohydrates.
- When mixed with water they form sticky and viscous liquids.
- Tragacanth and arabic gum.
- RESINS: They are complex and amorphous mixtures of organic substances.
- Danmar, colofonia, Kaurí.
- GREASES: Tasteless, odorless and colorless in pure form.
- Composed by Glycerides.
- Glycerides of stearic acid or tristearate are in sebum..
- Oleic, palmitic and butyric acids in butter.
- Silicone oils to facilitate the polishing of waxes.
CLASSIFICATION OF WAXES BY THEIR USE IN DENTISTRY
- TYPE I: Preparation of patterns directly in the mouth.
- TYPE II: Preparation of patterns with indirect technique.
- CALIBRATED WAX. PPR
- PREFABRICATED SHAPES. PPR
- Type I : Soft.
- Type II : Regular.
- Type III : Hard (hot climates)
- Total prothesis, patterns for orthodontic appliances.
- Partial prothesis, check the articular relationships in the mouth.
- Formwork: Baseboards
- Sticky: Making Rigid Keys
- Utility: Add on bucket flanks.
WAXES FOR IMPRESSIONS AND RECORDS
PROPERTIES OF WAX
- MELTING INTERVAL. By having molecules of different molecular weight and different types of molecules.
- THERMAL EXPANSION COEFFICIENT :
- They expand when temperature raises.
- They contract when temperature contraen al decreases.
- The temperature changes experienced by wax patterns after establishing critical dimensional relationships may represent an important factor that generates inaccuracies in the finished restoration.
- Process the waxes in the shortest possible time and with a minimum of ambient temperature changes.
- RIGIDITY: Allows fine grinding work without peeling.
- Plastic deformation on certain temperatures.
- Copy of details.
- It increases as the temperature of the wax increases.
- The waxes with lower melting temperature are more ductile. The same are those with wider melting intervals.
MECHANICAL PROPERTIES OF WAX
- PROPORTIONAL LIMIT.
- ELASTIC MODULE .
- RESISTANCE TO COMPRESSION.
PROPERTIES OF WAX
- CONCENTRATION OF TENSIONS:
- The manipulation, softening and plastification, molding, compression, carving induce tensions that are stored affecting the molecular structure.
- When softening it must acquire uniform plasticity that allows molding.
- When hardening it should be allowed to be carved with metallic instruments, to give shape and to be able to thin it in the edges or margins without fracture.
- It has contrasting color.
- It has dimensional stability.
- When evaporating it does not leave residues of more than 0.10% at 500ºC
- Paraffin 40-60 %
- Carnauba 25%
- It is the precursor of the cast restoration that will be placed in the prepared tooth.
- The procedure is done with the wax loss technique.
- A mold is made in a refractory lining, evaporating the wax in an electric furnace.
- Application of separator in the dies.
- An initial cap is made by introducing the die into a vessel with molten wax. Mantle or wax skin.
- Waxing is recommended step by step.
- The pattern should reproduce the proper anatomy of the patient’s teeth.
- They are flat or slightly concave from the contact to the cement-bonding joint.
- They should not be too concave or under-contoured because the use of silk would be ineffective.
- Over contouring causes difficulties in the maintenance of periodotal health.
- Contacts that are too broad make it difficult to control the plaque, can lead to periodontal disease.
- Small or punctual contacts can be unstable and cause travel.
- Poor contacts can cause impaction of foods that cause discomfort to the patient.
POSTERIOR CONTACT AREAS
- Occlusal third most, but between 1 and 2 upper molar in the middle third.
- Contacts in direction V – L:
- Mandibular teeth and maxillary molars generally in the middle of the occlusal surfaces.
- Between premolars and upper molars towards the buccal surface.
- Similar to adjacent teeth.
- Important: The location of the contour height is located in the gingival third of most teeth.
- In the lower molars usually lingual the contour height is located in the middle third.
- The contours generated by insufficient dental preparations make it difficult to remove plaque.
- The cusps and crests should be shaped in such a way as to allow a homogenous contact with the opposing teeth while stabilizing the teeth and directing the forces longitudinally.
- Point-shaped contacts.
- Non-functional cusps should be vertically and horizontally overlapped to avoid cheek or tongue bites and to keep food on the occlusal table.
HEIGHT AND LOCATION OF CUSPIDES
- The cones must be placed following the antero posterior curve (spee).
- Mandibular cusps that lengthen distally.
- Maxillary cusps are bounded distally.
- Evaluate the eccentric movements in articulator.
- In Wilson’s frontal plane, non-functional cusps shorter than functional cusps.
- Eliminate interference.
- VVertex of the triangle at the end of the cusp and base at the center of the occlusal surface.
- Close articulator every time crests are added.
- Two secondary ridges adjacent to each triangular crest.
- Convex with grooves where the convexities are.
FINISHING THE MARGIN
- The margins re-flow and end immediately before coating the wax pattern.