What is gear undercut?

Undercut – Gear Terminology The undercut of gears is also called deeper cutting and indicates the phenomenon of cutting the root of the gear deeper than the involute tooth curve. This can happen when there is interference between a tooth cutting tool and a gear or between the two meshing gears.

What is soft tissue undercut?

soft tis·sue un·der·cut (sawft tishū ŭndĕr-kŭt) Inward notching at the residual ridge or soft tissue of a dental arch that would influence the form of a removable denture.

How do you block an undercut?

Recently I have started to use Teflon tape for this purpose. I thoroughly dry the embrasure and using a cotton pliers pack the Teflon tape into the space. It sticks to itself and forms a custom shape to the embrasure and is tucked in, so it stays in place.

What is the cause of undercutting in gears?

Undercutting (cutting the tooth narrower closer to its base) is sometimes used to avoid interference but is usually not suitable because the decreased thickness leaves the tooth weaker at its base. In this situation Corrected gears are used. In corrected gears the Cutter rack is shifted upwards or downwards.

When undercutting occurs to avoid undercutting?

Undercut of a gear tooth can be avoided by:

1. decreasing the pressure angle.
2. improving the heat treatment.
3. using smaller rake angle for the cutter.
4. none of the above.

What is freeway space?

The interval between the upper and lower teeth when the mandible is in the physiologic rest position is commonly known as the freeway space. The freeway space is now generally recognized as a normal and necessary feature of normal occlusal function.

What is special tray?

Special Tray A special tray is defined as, “A custom made device prepared for a particular patient which is used to carry, confine and control an impression material while making an impression”.

Why is it important to block out undercuts?

Blocking out undercuts helps to aid the path of insertion. Some undercuts may need to be blocked our as they will interfere with the insertion of the denture e.g. A bony ridge: On insertion, if this wasn’t blocked out trauma will be caused to the overlying gingivae. (note: some undercuts we want to engage).

Why are undercuts blocked out?

With undesirable undercuts, impression material can get locked in the patient’s mouth because the material fills in between the teeth. When the impression hardens, there isn’t enough flex to remove the impression.

What does undercuts mean in dentistry?

Undercuts is a good thing when done to prepare a tooth for restoration that needs mechanical retention. So, this indicates undercut to be an area located on tooth where material is engaged and provide retention. Therefore, this term is mostly used in teeth preparation that place retention points for filling preparation.

What is the difference between a concavity and an undercut?

A Concavity: It is an area in a crown preparation or filling prep that, if you look down the path of draw of the prep, you can not see the tooth structure because it is concave and therefore blocked by the rest of the tooth structure. An area of a tooth: An undercut is the result of preparing a tooth for a restoration.

What does undercut mean in construction?

undercut, retentive, n an area of the abutment surface suitable for the location of a retentive clasp terminal, which in order to escape the undercut would be forced to flex and thus generate retention.

Are undercuts a help or hinderance?

Undercuts…be they natural in the jaw, the shape of a tooth, or the way to help hold in a filling…undercuts are angles that don’t allow for easy displacement or removal of an oral appliance, getting something caught under a bulge of a tooth or helping to keep a filling in place. The can be a help or a hinderance.

https://www.youtube.com/watch?v=hqJw6k74i6k