Thirty percent of conventional impressions received by laboratories are inadequate, according to respondents to LMT's State of the Industry 2010 Survey. Here, manufacturers offer impression-taking tips to share with your dentist-clients.
Seat impression tray with a slow, steady, vertical seating motion to allow for blending of tray/wash materials. ~ 3M ESPE
To reduce voids, use a stirring motion while syringing and keep the syringe tip immersed to avoid trapping air. ~ 3M ESPE
To avoid tearing at the margin and insufficient retraction, displace tissue to allow the impression material to better access the prepared area. Also use an impression material that ensures sufficient tear resistance, such as Impregum. ~ 3M ESPE
To ensure dimensional stability, the impression must be placed in a Ziploc® bag no more than 120 hours after washing, rinsing and removing excess water. ~ American Tooth Industries
If it's necessary to delay the pouring of the model, wrap a wet towel around the impression and store it in a plastic or sealed container. ~ Bosworth Co.
Always keep the material in front of and ahead of the syringe tip, and only push the material forward. Don't lift or pick up the tip while pushing the material around the margin. ~ GC America
Make sure the tray is adequate enough to allow 2mm. of impression material between the tray walls and the teeth. ~ GC America
Use passive pressure to hold the tray in position until completely set. ~ GC America
Don't allow the material to slump or drip into the oral cavity. ~ Kettenbach LP
Wash material should be syringed 360° around the preparation. ~ Kettenbach LP
To avoid pulls and voids, submerse the intraoral tip into the material until you finish syringing around the preparation. ~ Kettenbach LP
Use the correct type of double-bite impression trays to prevent distortion. ~ L.A.K. Enterprises, Inc.
Use a dual-phase technique for better accuracy. ~ L.A.K. Enterprises, Inc.
Use a double cord retraction technique to obtain a better impression. ~ L.A.K. Enterprises, Inc.
If your impression material fails to set around the prep, check to see if the retraction cord contains sulfates (ferric subsulfate or aluminum sulfate); both inhibit the set of PVS materials. ~ Parkell, Inc.
If you're using wash and tray materials from different manufacturers for single-step impressions, check the set times of both and leave the impression in the mouth as long as is needed for the slower-setting material to fully set. ~ Parkell, Inc.
When taking a second-wash impression inside a previously taken impression, relieve the contact areas of the first impression prior to taking the wash impression. This minimizes the possibility of tight contacts in your final restoration. ~ Parkell, Inc.