Lab Techniques for Flexible Partial Dentures Valplast Presentation - Peterson Airforce Base

Introduction to Flexible Partials Simple solution to provide a removable restoration No tooth preparation needed No metal frame needed Finished partial with one trip through the laboratory Injection Technique Valplast Partials are repairable and relinable Guaranteed not to break Valplast Presentation - Peterson Airforce Base

Type of Material Valplast is a type of Nylon Thermoplastic Injection Molded Denser than acrylic Lower Water Absorption than PMMA Flexural modulus around 470MPa at body temperature (making it both flexible and sturdy) In use since 1953

Lab Procedure - Overview Design, block and relieve master model Duplicate stone model Try-in (if required) or Set-up on Master Transfer set-up to duplicate model Wax with prefabricated patterns Invest, Sprue, Wax Elimination Process with Manual Injector Finish and Polish

Visually Survey Model Visualize design Aesthetics Path of Insertion Comfort Accuracy of Model Remove Discrepancies

Wrap-Around Clasp Most Common Clasp Hugs Tissue Minimal Coverage of Tooth Stability against vertical and rotational movement Design is made with Red Pencil

Split Wrap-Around Clasp Separated from Flange Similar to “Roach” Clasp Flexibility along Horizontal and Vertical Axes

Spur

Anchor

Maxillary Wax Relief Relief Wax placed along Buccal Periphery Necessary on All Maxillary Cases Use Hot Wax for Relief

Mandibular Wax Relief Junction of clasp with saddle is more rigid area. Undercut toward periphery must be relieved

Blocking and Relieving Lingual Undercuts Relieved Interproximal Spaces Closed Obstructive Undercuts Removed

Final Preparation Beading Post Dam Etching Design

Duplication Soak Model Prepare Flask Pour Gel Let set 15 minutes in air… …and 15 minutes in water

Waxing After Setup Use of Prefabricated Forms is Recommended to Insure Proper Thickness and Uniformity

Palatal Waxing Soften Palate Press to Position Seal all Borders

Buccal Waxing Using Prefabricated Form: Cut Form to Size Press to Model Seal all Borders

Bottom Half Investing

Spruing

Top Half Investing

Top Half Investing

Teeth Prepared for Retention

Processing

Melting - 11 Minutes

Injecting

Let’s See That Again...

After Processing

Pre-Finishing Econo-Cutter Trimmer Dark Grinding Wheels

Fitting and Rubberizing Vulcanite Burs Fitting and Rubberizing Brown Rubber Wheels

Polishing

Polishing Motion is Important

Advising Clinician on Insertion and Adjustment Partial must be placed in very hot water (150°F or more) for a minute prior to insertion and allowed to cool to a tolerable temperature. This process makes the partial as flexible as it would be at body temperature. This minimizes adjustments

Adjustments Minor clasp tightening or loosening can be done by heating the clasp again in very hot water and bending it severely in the needed direction. This will purposely warp the area enough to change its position Grinding should be done as a last resort. Use a Standard Green Mounted Stone (used usually for porcelain) to adjust Valplast. 20K to 30K rotation and constant motion

Small Additions - Welding Using hot air welder and welding rod, build up a boxing in the addition site to secure a new tooth Select a matching acrylic tooth. Break a porcelain tooth to obtain pins Heat each of two pins in flame to cherry red and embed in the partial half way (pin head protruding) Cure scooped stock tooth over pins using tooth-shade or pink acrylic.

Large Additions – Injection Wax new section on duplicate model to original partial Invest, Sprue, Wash out wax Prepare bonding site with acid etch solution (Val-Fuse Repair Liquid) Inject, finish, and polish

Relines Take Putty Matrix to record tooth position Strip teeth from partial (in blocks) while duplicating the model. Rewax new base using matrix to position teeth Invest and process using repair technique to bond top-half exposed Valplast to new base. Finish and Polish

Clinical Prep for Tooth Addition Clinician should take overall alginate impression to lift out case Counter-model for bite Before pouring the model, any deposits or adhesives should be removed from surface or the process will lead to an unintended reline.

Clinical Prep for Reline Closed-mouth rubber-base reline impression. Pick-up overall alginate impression. Counter not necessary