Advices and Curiosities

  • Curiosities
    Did you know that?
    • Natural teeth (mainly between young people) have a very active fluorescence? Such fluorescence is more noticeable in environments with intentional ultraviolet light (black light).
    • In the beginning of television broadcasting, it was normal to see a "pretty girl" with a dental flaw"?  It occurred due to the incident spotlights with a dose of ultraviolet light. And due to prosthesis without fluorescent pigment, it was "extinguished". Nowadays this does not happen anymore, since all resins intended to artificial teeth or crowns and bridges have fluorescent pigment already.
    • An exothermic reaction of a fast resin achieves more than 100º Celsius? Due this fact, bubbles appear if they are not repressed by pressure or heat dispersion. Have you ever imagined palate burning in a direct rebasing?
  • A lesson about acrylics
    A lesson about acrylics

    In this lesson, we will use a common language to the prosthodontist class.

    We will talk about "liquid" and "powder" acrylic, which are materials that are used by you so much, and its origin and manufacturing not all of you know about.

     

    ACRYLIC LIQUID (methyl methacrylate monomer): is a product comprised of acetone, hydrocyanic acid, and methyl alcohol. It looks simple, doesn´t it?  It exists since before World War II, but its production only started in Brazil after 1973, in Aratu (Bahia), in the petrochemical complex of Metacril.  

    Such liquid, when exposed to heat and light, tends to harden (polymerize). In order to prevent such polymerization and to be able to store it, an inhibitor, such as hydroquinone, hydroquinone methyl ether, or topanol is added. 

    In order to prevent light and heat effect, such liquid must be packed in amber colored vials and stored in ventilated area. This product is flammable, therefore, it must be packed far from the flames!

    If the inhibitor is eliminated and a catalyst is added, the liquid "will harden" more quickly and thus obtain blocks or plates with good translucence.

    In the odontological field, there are several applications and, for each one, there is a different preparation. In order to use it with "slow" resin for prosthesis, it must contain certain inhibitor percentage therein. When

    in case of more resistance, a Cross-Linker agent is put as "additive", which improves the resistance to solvents and something regarding to wear (unfortunately, we chew more than drink solvents, don't we?)

    In order to use it as fast resin (auto polymerizing), a reagent is added. 

     

    ACRYLIC POWDER (methyl methacrylate polymer), or acrylic resin: is "acrylic liquid" changed into "powder" by a suspension polymerization process.

    Such change happens with a reactor support, wherein the previously prepared "acrylic liquid" is placed - by shaking and heating, it is polymerized.  Separated by an auxiliary centrifuge, the "powder" is dried in incubators and sifted into suitable granulations for several applications, for which it is intended to.

    There is a wide variety of acrylic liquid preparations to obtain acrylic resins with different characteristics: 

    When only one type of monomer is polymerized, one homopolymer is obtained. When two or more monomers are polymerized, copolymers are obtained.

    The polymer is dimensionally stable.

    By varying the components it is possible to develop various types of polymers.

    Our polymerizable term (slow): CLÁSSICO, ONDA-CRYL AND POLICOR.

    Our self polymerizable (fast): JET COLORS, CLAS-MOLD, ORTOCLAS, COP CLAS, DENCÔR AND DENCÔR LAY.

    Each manufacturer keeps "in secret" the product used in its resins and the way to produce them, attributing to them this or that advantage. The good quality of an acrylic resin is, however, in the quality of monomer used, in the polymerization control, and in the suitable additive and pigment usage.

    Resin coloration can be made "integrated" (polymerization within a reactor) or by posterior addition. The use of a good pigment keeps the original color of the pieces.

     

    POWDER and LIQUID: We have already seen that powder arises from liquid. Now, both powder and liquid must work together, in suitable dosages for each application.

     

    CAUTIONS: Use clean measuring cups, mixers, and spatulas (they are found in our Kit-Pieces), as well as your hands. Nicotine stains in your fingers also stain the resins; as you can see, smoking is bad for everything.

    The monomers have slow toxicity but they must be used in ventilated areas and be little manipulated.

  • Usage of Thermo Polymerizable resin Clássico
    How to use Thermo Polymerizable resin Clássico

    The ratio between monomer and polymer must be careful, since liquid in excess will cause greater shrinking and bubbles. By using thermo polymerizable resin (Clássico), the ratio must be 1:3 - liquid and powder (exactly as indicated in the dosing cup, which is found in the liquid package). 

    1. Put the liquid (monomer) portion in the mixer and then the powder (polymer) portion;
    2. Stir for few seconds and close the mixer;
    3. When the paste is in plastic phase, i.e., by handling it pulling it in opposite direction it splits without fiber, fill up the cavity pushing with the fingers protected with a plastic sheet;
    4. With such sheet place above the filled up paste, put the closed muffle under a press;
    5. Slowly, make pressure and noticing the excess of paste appearing in the muffle borders. (Excess is always required).
    6. Open the muffle, again, and remove the excess and press, again, without the plastic sheet;
    7. Close the muffle and take it to polymerization.

    Polymerization

    1. It starts with cold water (muffle must not be in touch directly with the vessel).
    2. Simmer it for 1/2 hour;
    3. Turn off the heat for 1/2 hour and light the fire, again, in order to achieve boiling;
    4. Keep the boiling for 1 hour, at least;
    5. Let it to cool slowly, since fast cooling causes voltages that can cause distortions and breakage.
    6. After prosthesis deflasking, finish and mechanically polish it.

    (Note: Chemical polishing is not indicated for final prosthesis). It causes small tiny fissures in the surface, only visible with magnifying glass, which will cause early wear).

  • Using Onda-Cryl
    "Entering in the microwave furnace era"

    "Entering in the microwave furnace era"

    1. Read the your MWF guide, after all you must know it before scheduling;
    2. Power: the guide indicates maximum power of 800, 1000 watts or more. Any one works, but it is important knowing yours;
    3. How MWF operates? It contains an electronic device (magnetron) that changes electrical power in microwaves. They act over any moist substance, causing an ascending shaking of its molecules producing heat;
    4. Warning: Metallic containers must not be used within the microwaves. The microwaves do not penetrate them, going through their surface and becoming accumulated. In certain point such microwaves try to "jump" to the furnace walls, damaging it;
    5. Special muffle: due to the abovementioned reasons, it is required to use suitable muffles for using the furnace. Although they have metallic screws, such screws do not cause mentioned damages due to the way they are placed.
    6. Programming: If you read the furnace guide, you know program it, since it is required;
    7. Risks: There is no risk by using the furnace, since it have many devices that prevent a wave leakage, becoming it safe.

    Preparing muffle(s) for inclusion:

    NOTE: If the furnace has turntable, a total of two muffles can be used (BMF1)  at the same time.

    1. Initially, all inner muffle surfaces and borders must be isolated with viscous vaseline, which prevents the plaster paste to stick.
    2. Put the plaster up to half of the muffle. By putting the wax model, the plaster will raise and fill up to the normal level. Prevent the plaster from exceeding the limits of the model and muffle borders and smooth them down. Prevent the plaster penetration in the screw cavities;
    3. Isolate the plaster with a good insulating: our Isolak is excellent;
    4. Do the capping with a tooth wall protection;
    5. It can be die stone or special silicone die stone;
    6. Put it against the muffle and fill up with common plaster;
    7. Close the muffle and give a medium pressure with the press so that excess appears in the muffle holes and wait until its final fixation. 

    Wax deflasking in the furnace:

    1. Put the closed and screwed muffle on top of a turntable with small water layer, in a MWF of 1000 WTS, for 1' and 30" minutes at power of 100%. Such water will prevent the wax, if it run for any reason, from sticking in the bottom of the furnace turntable;
    2. After removing the plate and muffle, open it and remove softened wax;
    3. With a cotton wet in a home-made solvent, try to eliminate any wax residue;
    4. Put a cotton pellet wet with water, close the muffle without locking it and put in the furnace, again, for 1 minute;
    5. Remove the cotton and check if the plaster is wax-free.

     

    Isolating the plaster:

    1. Muffle opened, apply the insulating, e.g. Isolak, while it is slightly warm;
    2. Apply it with brush, spreading it and removing the excess;
    3. Await the muffle cooling in order to take the next step.

    Curing:

    In the case of total prosthesis with Muffle BMF1

     

    1. In the vestibular do characterization or press the pink one. Dosing: Using polymer Onda-Cryl in the optimal volume ration 1:3 - liquid and powder (generally, powder 21cc to liquid 7 mL is sufficient for the most of prosthesis) For palate:
    2. With a dosing cup, which follows the package, put a liquid portion in the mixer and, then, the polymer portion;
    3. Stir for few seconds and close the mixer;
    4. Wait the fibrous phase and fill it up (please, take notice that it is different from the conventional method, which indicates the plastic phase to fill up).

     

    Pressing:

    1. Slowly, press the paste coated by a thin plastic sheet;
    2. You should adapt the muffle so that its screws stay free;
    3. Slowly, press for the first time, with a strength about 500 kg. If there is not a  calibrated press, it worth to have experience;
    4. Open the muffle and remove the acrylic excess;
    5. Press again with about 1000 kg;
    6. Keeping the pressure, close the muffle using the screws;
    7. Wait for 30 minutes before taking to the furnace. If the prosthesis is thicker, wait for 1 hour.


    Caution: The screws are used to lock not to give pressure, so you need to give only 1/4 rotation with the suitable key.

     

    Scheduling the MWF in order to use muffle BMF1:

    The following is a programin 3 steps, which will attend to most of prosthesis: If your furnace has power of 800 watts, please follow the example:

    For 3 minutes at power of 40% of the capacity;
    For 4 minutes at power of 0% of the capacity (or minimum);
    For 3 minutes at power of 90 % of the capacity.

    Tips: If your furnace has power more than 800 watts, proportionally reduce the powers in indication 1 and 3. If lower, increase it. If two muffles are put therein, increase 1 minute in step 3.


    Programming for other microwave powers:

    Maximum power in Watts  (W) Step 1 (3 minutes) Step 2 (4 minutes) Step 3 (3 minutes)
    800 to 900 W 40% 0% (minimum) 90%
    1 000 to 1 100 W 40% 0% (minimum) 80%
    1 200 to 1 300 W 30% 0% (minimum) 60%

     

    Cooling: Wait the muffle to cool naturally. Do not put cold water in order to not damage it and so it does not become a fragile prosthesis. Then, finish, polish it etc.

     

    Curing:

    In the case of partial prosthesis with Muffle BMF2

    Dosage: Using Onda-Cryl polymer in optimal ration 3:1 - powder and liquid, in the volume to be calculated as per case. For crowns or veneers, use Clássico polymer, for crowns and bridges with slow polymerization use Dencôr line with Onda-Cryl liquid. 

     

    Pressing:

    1. Press with about 600 kg strength.

    Programming the MWF in order to use muffle BMF2:

    A - For wax deflasking use 40" at power of 100%

    B - For polymerization use the following programming::

    1. For 3 minutes at a power of 30% of the maximum capacity;
    2. For 4 minutes at a power of 0% (pause);
    3. For 3 minutes at a power of 60% of the maximum capacity.

    C - Your furnace can polymerize several prostheses in the small muffles BMF2 at the same time.

    1. For 2 muffles keep the abovementioned scheduling;
    2. For 4 muffles, increase polymerization phases to 40% of the capacity and the last phase to 90% of the maximum capacity of the furnace.


    NOTE: The parameters indicated can be small ranges, depending on the furnace used and the room temperature.

  • Curing of Braces
    Description of the curing methods of braces

    Prepare the model in plaster, since the metallic components are already fixed:

    1. Isolate it with thin insulating layer (Isolak).
    2. Put the base of the model in a container with a water layer at 4 to 5 mm;
    3. Wait hydration, which is carried out by water absorption by the plaster of the model;
    4. When you notice color change in the model surface, consider it adequately hydrated.

    Curing:

    A - Method of the early polymer monomer mixture

    (Note: if you intend to perform chemical polymer, use liquid Jet instead of liquid OrtoClas).

    1. In a proper container put a ratio 2.5:1.0 - polymer and monomer. Example: powder 10 mL: liquid 4 mL. 
    2. With a spatula 7 distribute the mixture, while it is fluid, first below the clamp and metallic pieces.
    3. After distribution, with spatula always wet in monomer, give the first finishing removing the excess.

    B - Distribution method, by steps, for polymer monomer

    1. With a pipette, wet the model surface with monomer where the polymer will be applied.
    2. Carefully, distribute the polymer in the area, which was wet by monomer, using a dosing cup, or bottle with adosing dispenser. 
    3. Again, over the resin put some monomer drops.
    4. Fill up whole model area like that.
    5. Repeat the operation with a new layer.
    6. Realizing the model is adequately filled up, smooth all surface.

    Polymerization:

    1. Noticing that the resin surface is opaque, immediately take it to the OrtoClas appliance, wherein a hydraulic pressure will be given 125 to 30 pounds. Do not drop the pressure under 25 pounds.
    2. Let it under pressure for about 20 minutes.
    3. After removing the piece out of the Orto Clas appliance, finish and mechanically or chemically polish it.

    Procedures for preventing bubbles:

    1. Do not place the model in the bubble removal equipment with the very hard resin, in an advanced stage of the polymerization, because it will not be sufficient time to react pressure on the resin.
    2. Do not hydrate the model excessively.
    3. If the model is not adequately hydrated when putting it in the Orto Clas appliance with the proper pressure (25 to 30 pounds), it will absorb more water, dropping the pressure and causing bubbles.
    4. When the curing method is performed in the powder/liquid method, it must be done quickly since, if there is delay, by finishing the last layer, the first one is already polymerized and will present bubbles even if it is put in the Orto Clas appliance.
  • Using Clas-Mold resin
    Method of using Clas-Mold resin

    Clas-Mold resin was developed for mold and plate-base confection.

    Its using is simple.

    With the dosing cup, which comes with the package, separate 24 cc of polymer (full dosing cup) and 6 mL of monomer for an individual mold. For a plate-base, separate 21 cc of polymer and 5 mL of monomer.

    1. Perform the dosing and mixture in the mixer;
    2. Wait 1 minute and remove the mixture;
    3. Perform molds or plate-base confection as you always do or use the template in our Kit Pieces.

    Template using method

    1. Cut two thin transparent plastic sheets 15 ? 15 cm and put one of them over the template.
    2. Remove the mixture from the dosing cup and put over the sheet, which is above the template, then, cover the mixture with the remaining sheet.
    3. With a glass plate, press the plastic so that the mixture is distributed and fill up uniformly the template space;
    4. After modeling the mixture, remove only one plastic sheet.
    5. Without the plastic, take the paste over the isolated plaster model and first press the central part over the palate;
    6. Keeping the pressure, turn down the paste over the model borders until the contour limits;
    7. With a Le-Cron, cut the excess and, with it, model a handle for the mold, which will be positioned later; 
    8. Wait the polymerization before detaching from the model in order to finish.

    (Note: if you use colorless Clas-Mold, let it polymerize under pressure in the Orto Class appliance).


    Remarks: approx. time of work 15 minutes with temperature at 23 ºC.

  • A lesson on waxes
    A lesson on dental waxes

    It has as components: paraffin, ceresin, carnauba wax, bee wax. Use aniline for coloring it.

    Pink wax is the most used, in which the components, previously dosed, are melted, put in forms, from where the obtained blocks are laminated.

    Pink wax is numbered as 7 or 9. It aims to have a type of more suitable wax to use in heat (9) or in cold (7). In some countries, it is called WINTER or SUMMER. In Brazil, with its wide territory, it is required to indicate it as 7 and 9, since at the same day there are all the climate seasons.

    We work with other wax options: Utility, Articulation, Wax Plan, and Macro Block.

     

  • A lesson on insulating
    An insulating lesson for plaster/resin

    Generally, it has as basic component an alginate acid and a preservative for preventing deterioration and, in some cases, an aniline in order to color it.

    In stainless steel tanks, the dissolution of all components is performed, then, they are packed in vials. That is the way our Isolak is performed. 

    In order to use it, you must separate a required quantity in a bottle and use a brush, which must not be wet within its original package. 

    Isolak is applied over the plaster model and reacts with it, forming a thin insulating film.

  • Naturalization process
    Naturalization methods with Kit Policor-Natura

    Materials:

    1. Kit Policor-Natura contains the collection of pigmented resins, veins, auxiliary pieces, and guide.
    2. A vial of Isolak, insulating for plaster.
    3. A vial of thermo polymerizing liquid,  Onda Cryl, which contains cross-link. With this kit, polymerization can be performed both by traditional and microwave process.
    4. Also, keep a color collection for the slow resin palate Clássico or Onda-Cryl: for types 1 and 2, normal with veins (NV); for type 3, medium with veins (MV), and for type 4, dark with veins (DV). And, if you want, colorless or crystal resin in the palate.

    Method description

    Once the patient physical type is determined, to whom the prosthesis is intended to, and having as parameter the correspondent picture, the process is started after removing wax and perforating the teeth for retention.

    By handling plaster wall, use insulating for plaster and resin (our Isolak is excellent). If it is silicone wall, do not isolate where there is silicone.

     

    Sequence (it is used for the four types)

     

    1st step - Interdental papilla

    Fill up with naturalization resin in the color indicated in the picture between the teeth (battlements). Then, the resin will be wet with monomer by a pipette, always dropping in the resin basis, taking care not to leave liquid in excess.

    In the labial frenulum region and in the posterior part to the canine protuberance, this resin must be "pulled" up to the border. So, the labial frenulum and the canine protuberance are evidenced.

    Remarks: in type 4, for best imitation of the melanin pigmentation, several islets with black pigment must be performed from the place of the inserted gum throughout all the prosthesis body.

     

    2nd step - Inserted gum

    In the place correspondent to it, put resin in an indicated color sufficient to cover the teeth "roots" by vestibular and lingual, which is then wet with monomer.

    If there is intention to put veins, do it right after, pulverizing before a fine layer of body resin, distributing over it, the filaments, red for type 1, 2, or 3, purple and red for type 4. Wet again with monomer.

    In the canine protuberance and labial frenulum, the same resin must be applied up to the border.


    3rd step - Gingival contour

    It separates the inserted gum from the body. The same papilla coloring is used. With resin in the indicated color, a dividing line from the second molar is performed, in both sides, up to the canine protuberance and from there up to the labial frenulum.


    4th step - Body

    Fill up the whole vestibular with body resin, then wet it with monomer. Slowly press it, with the model protected with a thin plastic sheet, checking if there is resin excess. If there is, cut it using an instrument wet with monomer in the tip.


    5th step - Palate

    Put 21cc of palate resin in the dosing cup, in the indicated color for the physical type, mixing at 7 mL of the acrylic liquid. In the fibrous phase, slowly press it using a thin plastic sheet.

    Open it, remove the excess, and press again. Keep the muffle pressed (or locked) for one hour before taking it to polymerization by traditional or furnace process.

     

    Training model - Scale

     

    Attached to Kit, there is a rubber template, in which a half arch can be reproduced.

    Perform the inclusion of this rubber half arch, duly lubricated with vaseline, in a partial muffle, using common plaster.

    After fixation, isolate with Isolak and finish filling up the muffle with common plaster.

     

    After opening the muffle and separating the parts, remove the rubber model without damaging it in order to reuse it.

    In the gap left by the arch, perform your training, following one of the chosen types.


    So, you will able to produce some pieces that will serve as scales.