Wrong plaster type class used

It is recommended to always use type class IV plaster. Type class I and II plasters have a porous surface and soak up too much of the isolating solution.

Soaking the plaster models in the pressure pot

Soaking in the pressure pot pushes water into the gypsum pores. Models "sweat out" excess water when they are exposed to atmospheric pressure again. This lifts the isolating film from the plaster surface. Always soak models in water without pressure.

Wax removers and / or the duration of the boiling-out process influence the plaster surface

When using automatic boiling-off machines, make sure to use suitable additives and their dosage. Heat models for 5 min, remove wax in its plastic state and under no circumstances wait until it has completely liquefied in the boiling-out unit. Briefly steam off models again after they have been boiled out. Do not expose the plaster surface to thermal stress caused by boiling-off for an unnecessarily long time. Clean boiling-off units regularly!

Wax-on-plaster isolation was used

These materials often contain essential oils that prevent the alginate from isolating the plaster properly. The oil film on the plaster surface prevents the plaster from sealing with the alginate isolution. Thoroughly clean the models.

Contamination of the alginate isolating solution by gypsum particles (calcium ions) in the storage container, in the drip tray, etc.

Always use fresh isolation (disposable method), clean the brush before isolating and do not put the used brush back into the container with the alginate isolating solution.

Acrylic briefly mixed, doughing phase too short

Adhere to the mixing ratio of powder and liquid, mixing time and doughing phase according to the instructions for use.

Incorrect polymerisation pressure

Make sure that the pressure in the polymerisation unit is neither above nor below 2 - 2.5 bar. The precisely set pressure prevents the formation of bubbles at boiling point during the exothermic reaction phase.

With heat-curing acrylics

Incorrect polymerisation control, formation of boiling bubbles due to rapid heating (heat-curing polymers); First heat the heat-curing polymer to 70 °C in a water bath, hold for 20 min. Then raise the water bath to boiling temperature and boil for 30 minutes, then let it cool down slowly in the water bath.

With cold-curing acrylics

Water temperature too high in the water bath; Do not exceed a water bath temperature of 50 °C for cold-curing polymers.

Flask and / or plaster models too hot from boiling-out

Allow to cool to room temperature, plaster model not sufficiently soaked in water; Before applying the acrylic, soak plaster models in clear water at room temperature for at least 10 minutes.

Mixing-ratio not adhered to

Use of measuring aids. Pour the powder loosely into the measuring aid, but do not tap down / compact, if necessary reweigh! Too much monomer leads to greater shrinkage of the acrylic.

Too little acrylic (press process)

Make sure there is enough acrylic and press reservoir.

Acrylic inadequately placed in undercuts (press process) results in trapped air 

When pressing/packing in undercuts, use small amounts of acrylic dough. In the case of heat-cure polymerisation process, “in-between-pressing” is recommended using polyethylene foil.

Pressure drop during polymerisation; If the pressure falls during polymerisation, the boiling point of the monomer falls and boiling bubbles occur.

Check and adhere to the specified polymerisation parameters. Too much monomer used. Use the measuring aids. Too much monomer causes the acrylic to shrink more strongly.

Isolation layer too thick

Apply a thin layer of isolation 1 to a maximum of 2 times. Further layers do not improve the isolation. Carefully rinse off excess under a soft jet of water, there must be no "puddles of isolation". The isolated surface should look "greasy".

Cooling down too fast 

After the heat-curing process, allow the flask to cool down slowly to room temperature to avoid tension in the acrylic.

Too much pressure when polishing

Polish with low pressure using a damp cloth. Otherwise, a thermal load leads to tension, deformation and possibly "burns" on the polished surface.

Incorrect polymerisation pressure

Polymerise cold-curing polymers for 15 - 20 min at 45 °C warm water and 2 - 2.5 bar.

The doughing time of the acryic is not taken into account

Let the acrylic set until it is in a plastic state (can be modeled). Then place it into the pressure pot.

Polymerisation temperature too high for cold-curing polymers

Do not exceed 50 °C water temperature.

Thermal and mechanical stress on the acrylic after polymerisation

Avoid any thermal and mechanical stress as far as possible after curing.

Teeth not sufficiently fixed in the matrix 

Apply a tiny drop of superglue onto the labial surface of teeth and fix in the matrix. Ensure that it is completely removed after polymeriation.

Flash when using the flask technique

Due to the system, a flash remains between the flask halves when the press process is used. This causes a bite raise of 0.5 to max. 1.0 mm and can be corrected in the articulator by targeted grinding of the occlusal surfaces. If the flash is unusually thick, it must be checked whether the press pressure on the hydraulic press is sufficient; if necessary, check the pressure with a special pressure gauge. Also check the flask bracket for stability. Check the consistency of the doughed acrylic, doughing time exceeded (see instructions for use), avoid drying out of the acrylic dough by covering the mixing pot.

Press process with cold-curing polymers, the acrylic was processed too slowly in the starting polymerisation phase

If a cold-curing polymer is processed in the pressing process when polymerisation begins, the acrylic solidifies too quickly during the press process. In this case, the flask can no longer be closed exactly. The result is a raised bite. A close observation of the acrylic during the doughing phase can help. Exact “timing” for the correct processing time is crucial and may require some practice when handling cold-curing polymers. If necessary, store the monomer in a cool place, this will extend the processing time.

Trimmed undercut models are used for gel investment in the pouring process

Always trim models at right angles (90°), otherwise they cannot be repositioned correctly and the gel will deform in the process.

Shrinkage of the base due to high monomer content (casting process)

When using the PremEco Line casting flask, this can be redressed by placing a foil of 0.1 mm thickness between the model and the base of the flask in the dorsal area.

Acrylic on the teeth. Insufficient fixation in investment or the matrix

Apply a tiny drop of superglue on the labial surface of the teeth and fix. Ensure that it is completely removed after polymerisation. Before investing, make sure that there is no more wax on the teeth. In the case of gel investment, free the cavities of residual water before repositioning the teeth so that the teeth can be safely positioned again and are not pushed up by residual water.

Water content in the gel too low due to evaporation (casting process)

If necessary, add some water when melting.

Gel was heated too much, severe water loss (casting process)

Store dublicating gel in a closed container after use. Add sufficient water to the gel when remelting. When using gel machines, ensure precise temperature control during the heating phase. The gel must not boil, as this would destroy its structure. It is advisable to occasionally check the temperature of the gel both during the melting phase and during the preparation with an external thermometer. The temperature set for the device can sometimes differ significantly from the required temperature (see instructions for use). If the gel is only required occasionally, it can be heated in portions in a microwave (see instructions for use).

Insufficient impression

When checking the impression, ensure that the retromolar tuberosity and / or trigonum are precisely registered.

Significant shrinkage of the denture base due to the use of too much monomer

Adhere to the mixing-ratio of powder and liquid, mixing time and doughing phase according to the instructions for use. Determine the powder-to-liquid ratio by using measuring aids or by weighing.

If the doughing phase of the acrylic is too short, so-called suction shrinkage occurs, especially in thick areas of the denture base

Adhere to the mixing-ration of powder and liquid, mixing time and doughing phase according to the instructions for use. Determine the powder-liquid ratio by using a measuring aid or by weighing.

Dosage not adhered to, monomer content too high during mixing

Note the mixing-ratio, use a measuring aid. To reduce the residual monomer content, store the polymerised dental restoration in the finished (sanded) but not polished state for approx. 48 hours at room temperature in water, if possible before fitting.

Pressure points from malocclusion or inaccuracies of fit

Re-articulate and grind bite raised areas after polishing, especially in dentures made by using the press process.

Rough basal surfaces

Note plaster processing. Disinfect and neutralise the impression according to the manufacturer's instructions. Avoid excessive thermal effects, keep evaporation and boiling-out to a minimum. Apply a maximum of 2 thin layers of isolating solution. Further layers do not improve the isolation, carefully rinse off excess under a soft jet of water, there must be no "puddles of isolation". The isolated surface should look "greasy". Always use fresh and clean isolating solution, always use clean brushes for application. Protect isolating solution from contamination. Rinse the brush carefully with clean water after use.

Possible hypersensitivity

Clarify whether the patient has an allergy record, otherwise clarify which dental restoration materials have been used so far. If information is not available, a doctor should be consulted.

If the patient is known to be sensitive to denture acrylics, we recommend further reducing the residual monomer content:

• Storing the polymerised dentures in the finished (sanded) and not highly polished state in water for up to 48 hours before delivery/incorporation
• It is essential to observe the mixing ratio and the processing instructions in the instructions for use
• If necessary, switch from the pouring to the injection method (Swiss Jet or similar)
• If necessary, switch from cold-curing to heat-curing acrylics (Promloux^®, Promolux^® High Impact)

These notes apply to:

• The cold-curing denture acrylics (Weropress^®, Combipress, PremEco^® Line)
• artConcept PLUS