Tips for the H&H Cordless Impression Technique

Hydraulic & Hydrophobic (H&H)
Impression Technique with PerfectIM Systems

By Jeffrey C. Hoos, DMD, FAGD
As appeared in J. Morita's News & Views

PerfectIM Systems Vinyl Polysiloxane Impression Material offers accurate final impressions of subgingival margins without use of retraction cord, gingival excision or application of hemostatic agents. These materials are cartridge dispensed, radiopaque, hydrophobic, tasteless, odorless and most are thixotropic. A range of working/setting times is available for any impression procedure. Below are tips on how to use this material for the unique, H&H Cordless Impression Technique.

1. Use FREE ACCESS II cheek and lip retractor to better visualize the field.
   
   
2. Apply 30 SECOND BLUE VELVET on mandibular occlusal table. Due to the thixotropic characteristics, the material can be stacked as much as necessary.
   
   
3. With the cheek retractor remaining in place, ask the patient to close. This will aid the patient to close in centric occlusion.
   
   
4. While closed in centric, remove the cheek retractor and the patient's tongue and cheek will now form the flanges of a facsimile tray. This method is for single tooth impressions.
   
   
5. Hold the maxillary portion of the impression in place and ask the patient to open. Keep the impression on the opposite arch of the prepared tooth. For example, if a mandibular impression is being taken, leave the impression to rest in place on the maxilla.
   
   
6. Without changing the position of the maxillary impression, air dry both the mandibular impression and the preparation, then place a small amount of 30 SECOND FLEXI-VELVET OR 30 SECOND SNOWHITE directly into the preparation of the primary impression. Do not apply it to the prepared tooth.
   
   
7. Now ask the patient to close firmly, make sure they are fully closed. To ensure the patient bites during the setting process, hold the mandible with light pressure.
   
   
8. Remove the impression after one (1) minute. A sideless triple tray should be used for multiple tooth impressions. Apply the BLUE VELVET (2 working/setting times available) on the mandibular and fix the tray in place. Check for possible interference due to the tray then apply the material on top of the tray. Ask the patient to close. Now follow the procedure as stated above with the FLEXI-VELVET OR SNOWHITE of your choice. One of the differences with this technique is that the material is positioned with full vision, as opposed to a loaded tray with no vision.

Flexi-Velvet Impression

SnoWhite Impression

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