Whether you are a dentist, a dental hygienist, a dental assistant, or a patient, taking dental impressions is probably one of your least favorite activities.
Someday, every dental office will use nothing but digital impressions. But for many offices, that day is far in the future. Until then, taking accurate impressions using conventional materials, such as alginates and polyvinyl siloxane, will continue to be the standard of care in most offices for many more years.
Why Dental Impressions Matter
Taking accurate impressions of a patient’s teeth and adjacent structures is important for all aspects of dentistry–from diagnostic casts, to dentures, to crowns and bridges, to implants. This skill represents ground zero for many restorative and diagnostic services.
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Without accurate impressions, neither the lab technician, dentist, nor auxiliary staff can produce functional restorations.
The Challenges
Taking impressions is not a simple task. Problems caused by the patient’s oral anatomy, gag reflex, properties of the material, and even the room temperature can negatively affect the outcome.
The following tips can help you avoid retakes and ensure that your impressions are accurate every time.
Choose the best impression tray
Your first decision is whether to use a stock or custom tray. Custom trays produce great impressions and are comfortable for patients. Metal or plastic stock trays are inexpensive, but you must take care to block undercuts and choose the size carefully to avoid patient discomfort.
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Try the tray in prior to loading the material to ensure that it fits over the full arch. Allow the patient to experience how the empty tray feels coming in and out of the mouth.
Minimize the patient’s gag reflex
For patients with a strong gag reflex, use the smallest amount of material possible, while still capturing all the necessary details. Adjust the chair so the patient is sitting upright and leaning slightly forward. Next, ask the patient to concentrate on slowly breathing in and out through his or her nose.
Distraction works well for some patients. Consider asking the patient to slowly raise and lower one foot off the chair as a diversion from the tendency to gag. Give verbal updates on what you are doing, the amount of time left, or how the material is setting up.
Provide the patient with a paper towel to dry the chin in case drooling occurs.
Care for margins
Air dry the prep paying special attention to the margins. Drying keeps them clear of blood, saliva, and debris that could cause distortion. Use hemostasis agents along with retraction products to ensure precise reproduction of the margins.
Prevent voids
One common issue with impressions are voids on the margins. This might be caused by the inadvertent introduction of air when filling the syringe.
Avoid articulation problems caused by voids on the occlusal surfaces by carefully drying any moisture from those areas before inserting the tray.
Watch expiration dates
Always check the manufacturer’s expiration date. Using outdated materials can cause impressions to be warped or inaccurate, resulting in expensive or uncomfortable retakes.
Take your time
Never rush an impression. Carefully pack the retraction cord and allow enough time for the tissue to respond. Removing the tray before the material is completely set results in tearing and rough surfaces and might cause the restoration to be tight or short.
Follow directions
Impression materials vary widely between manufacturers. Slight differences in water or air temperature can alter the outcome. Even after you are comfortable with your favorite brand, continue to measure carefully, using only the measuring devices that come with the material.
Additionally, consider using a timer to keep track of mixing and set-up time.
Conclusion
Until digital impressions become the standard of care, dentists and staff members must continue to improve their techniques using conventional materials. Time-tested products, such as polyvinyl siloxane and alginate, continue to be the most common materials for impressions. Because this is a service that dentists often delegate to their auxiliary staff, effective training must be provided, and ongoing quality controls must be maintained to avoid costly remakes and patient discomfort.
Simple steps like choosing the tray, controlling gag reflexes, paying attention to margins, following directions, watching expiration dates, preventing voids, and conducting the procedure carefully and methodically will help ensure an incredible impression every time.
The lab technicians here at First Choice Dental Lab® can answer your questions regarding best practices for taking impressions.
Also, make sure to check out our dental resources page HERE for everything from impression troubleshooting to step-by-step instructions on implant scanning!
If you’re ready to give your patients a reason to smile, we’re here to help. Contact us to today to get a fee schedule, or send us your scans
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About First Choice Dental Lab®
We’re a full service dental lab with locations in Downers Grove & Downtown Chicago, IL. We manufacture & customize quality dental restorations for general dentists. From in-house work to outsourcing, we create smiles based on your needs and budget. We’re here to help you give your people a reason to smile!
Bibliography
http://www.dentalproductsreport.com/dental/article/10-golden-rules-taking-impressions
https://www.dentistryiq.com/front-office/article/16357203/7-tips-for-taking-accurate-impressions
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813082/
https://www.dentalhygiene411.com/oral-health/alginate-impression/
https://www.researchgate.net/publication/320046633_Dental_Impression_Materials_and_Techniques
https://www.ncbi.nlm.nih.gov/pubmed/28886768
Cervino, Gabriele, et al. “Alginate Materials and Dental Impression Technique: A Current State of the Art and Application to Dental Practice.” Marine Drugs, vol. 17, no. 1, Dec. 2018. EBSCOhost, doi:10.3390/md17010018.