Today AM – Need Ney Surveyor PM - Clinic Get Casts, Typodonts & Marking Sheets at front Presentations and Videos Survey Class I & II Casts (‘TYPO’)(w/o preps) Tripod Casts Get Mannikin Heads & Mounts ready for PM PM - Clinic Prepare guiding planes on Class I & II Typodonts (last sheet Course Sched) Formative Marking sheets

Surveying, Path of Insertion, Guiding Planes

Definitions Height of contour Suprabulge Undercut = Infrabulge

Definitions Height of contour Undercut = Infrabulge Suprabulge

Rule: Retentive tip should usually be designed to be placed in the gingival 1/3

Path of Insertion Path that the prosthesis is Placed/removed Usually a single path

Advantages of a Single Path of Insertion Equalizes retention

Advantages of a Single Path of Insertion Bracing and Cross-arch Stabilization

Advantages of a Single Path of Insertion Minimizes torque on abutments

Advantages of a Single Path of Insertion Allows removal without encountering interferences

Advantages of a Single Path of Insertion Directs forces along long axes of teeth

Advantages of a Single Path of Insertion Provides frictional retention

Selecting a Single Path of Insertion Use a dental surveyor to Select path Prepare guiding planes

Parts of a Surveyor Surveying Movies: Parts of a Surveyor Surveying

Guiding Plane Preparation Where rigid components contact abutments Proximal Plates Bracing Arms Rigid portions of Retentive Arms

Other Uses of a Surveyor Blocking out undesirable undercuts Ensures the framework is not cast in an undercut

Selecting a Path of Insertion Orient cast relatively horizontal Final tilt rarely more than 10° from horizontal

Selecting a Path of Insertion Place analyzing rod against abutments Contact point is Height of Contour Below is infrabulge Above is suprabulge

Selecting a Path of Insertion Tilt cast to obtain maximum parallelism Heights of contour are at relatively same position occluso-gingivally Equal amounts of undercut

Altering Path of Insertion Proximal surfaces similar undercuts Retentive areas similar undercuts

Selecting a Path of Insertion Modify tilt if necessary Soft tissue interferences

Selecting a Path of Insertion Modify tilt if necessary Esthetics

Once Path Selected Instructor: Approves path Demo: Mark heights of contour with carbon marker Tripod

Selecting a Path of Insertion Lock cast position & tripod

Tripoding

Optimal Path of Insertion Retentive undercuts equalized Retentive arm has a different path of escapement than guiding plane, so it must flex during removal

Optimal Path of Insertion Retentive undercuts equalized Ideally, retentive arms should oppose each other on opposite sides of the arch

Optimal Path of Insertion Minimize severe tooth & soft tissue interferences

Optimal Path of Insertion Esthetics Minimize display of clasps, metal components

Optimal Path of Insertion Prepare Guiding Planes Flat surfaces parallel to path of insertion Control & limit movement of RPD Initial contacts for RPD

Guiding Planes Stabilization

Effectiveness of Guideplanes Most effective when: Parallel to each other More than one common axial surface

Effectiveness of Guideplanes Most effective when: Directly opposing each other

Effectiveness of Guideplanes Most effective when: Prepared on several teeth Cover a large surface area

Preparing Guiding Planes Assessing Guide Planes Movies: Preparing Guiding Planes Assessing Guide Planes

Assessing Guiding Planes Proximal View Carbon Markings Facial View

Preparing Guiding Planes Select path of insertion Design Partial Denture * Select number & position of guiding planes Prepare guiding planes

Use Surveyor to Align Bur Intraorally When Preparing Guide Planes Cast should be on Surveyor Close to Operator to Compare Orientation of Analyzing Rod and Bur to the Tooth

FINGER REST!

Burs 8837K-014 Long Cylindrical Carbide or Diamond (8837K 014)

Guiding Plane Dimensions

Axial Surface Already Parallel to Path of Insertion NO Preparation !

Polish Prepared Surfaces Rubber wheels or points

Prepare Guiding Planes First

Effects of Guiding Planes On Retention & Stability Maintains Retention

Effects of Guiding Planes On Retention & Stability Minimizes Need for Retention

Effects of Guiding Planes On Retention & Stability Stabilizing Teeth

Marking Sheets

Other Alterations of Axial Contours Lowering Heights of Contour Rigid elements contacting abutments Improve esthetics Prepare guiding planes - most efficient method to lower

Other Alterations of Axial Contours Raising Heights of Contour Insufficient retention in gingival 1/3 (at least 1mm from gingiva) Prepare undercut Add resin above to create undercut

Preparing Retention Axial surface must be close to parallel the path of insertion

Retentive Preparation Shape Follows the path of designed retentive tip

Creating Undercuts with Bonded Resins Axial surface must be close to parallel the path of insertion

Summary of Abutment Modifications After RPD Designed Guideplanes Lower heights of contour to eliminate interferences & improve esthetics Create undercuts if absolutely necessary (raising heights of contour) Rest seat preparation