RPD surveying: in 10 mins - RPD ( Removable Partial Denture) online Course

Summary

This video provides an in-depth explanation of surveying in removable partial denture (RPD) design. It covers key concepts like retentive undercuts, guide planes, and rest seats. Using a Nay surveyor, the video demonstrates how to determine the path of insertion and undercut depth, crucial for designing an RPD. It also explains the importance of drawing survey lines and tripoding to maintain cast positioning. The video concludes by introducing software solutions for easier, more precise surveying and cast design.

Takeaways

• 🦷 Retentive undercuts are areas below the height of contour where clasps engage, aiding in retention for an RPD (Removable Partial Denture).
• 🛠️ Guide planes are flat surfaces on abutment teeth next to edentulous spaces that help guide the insertion and removal of partial dentures.
• 🔧 Rest seats are prepared areas on the teeth that accommodate the occlusal rest of an RPD framework.
• 🧭 A surveyor, such as a Nay surveyor, helps determine the path of insertion for an RPD and the location and depth of undercuts.
• 📐 The mandrel of the surveyor represents the path of draw, and the table's angle relative to the mandrel determines the angle of guide planes during tooth preparation.
• ⚖️ In cases with tipped teeth, divide tooth preparation between adjacent teeth to avoid excessive damage to either tooth.
• ✏️ The survey line, drawn using a lead marker on a cast, represents the height of contour, and different undercut gauges measure the depth of undercuts.
• 📊 Different clasps require different undercut depths, and it's essential to locate and measure undercuts for proper RPD design.
• 💡 Classification systems for survey lines help determine the location of undercuts in relation to the edentulous space (Class 1, Class 2, and Class 3).
• 🗺️ Tripoding is the final step in surveying, marking three points on the cast to allow for re-positioning after changing the table's tilt.

Q & A

What is the purpose of retentive undercuts in an RPD?

Retentive undercuts are areas below the height of contour of the tooth where retentive clasps engage, helping the RPD stay in place, providing retention.

What are guide planes and why are they important in RPD design?

Guide planes are flat areas on the surface of abutment teeth next to the edentulous space. They provide guidance for the insertion and removal of a partial denture and are essential for controlling the path of draw.

What is the function of rest seats in an RPD?

Rest seats are areas prepared on the tooth surface to accommodate an occlusal rest on the RPD framework, providing support and stability to the partial denture.

What tool is used to determine the path of draw for an RPD?

A Ney surveyor is used to determine the path of insertion and removal of an RPD, as well as to locate and measure the depth of undercuts.

How does the Ney surveyor help in guide plane preparation?

The Ney surveyor helps in determining the angle for the guide planes by positioning the cast at the correct angle relative to the mandrel, which represents the planned path of draw.

How do you survey teeth with different angles, such as a tipped premolar and molar?

When teeth are tipped in opposite directions, it’s important to divide tooth preparation between both teeth, avoiding excessive reduction of one tooth and ensuring both follow the correct path of draw.

What is the purpose of drawing a survey line?

The survey line represents the height of contour on a tooth. Below this line are undercuts where clasps engage. Drawing the survey line helps identify these areas for proper clasp placement.

How do you measure the depth of an undercut on a surveyed cast?

To measure the undercut, an undercut gauge is used. The shank of the gauge touches the height of contour while the disc measures the undercut depth, typically 0.01 or 0.02 inches.

Why do different clasps require different undercut depths?

Different clasps require different undercut depths because the amount of retention needed varies. Reciprocal elements, like reciprocal clasps, must stay above the survey line to function properly.

What is tripoding, and why is it important after surveying a cast?

Tripoding is the process of marking three fixed points on a cast to ensure it can be repositioned in the same tilt during future adjustments. This helps maintain consistency in the RPD design process.