The possibility of a dental impression dislodging a tooth is a common concern, but for a healthy, stable tooth, the risk is negligible. A dental impression is essentially a negative mold of your teeth and the surrounding soft tissues, used to create a positive replica for fabricating custom restorations or appliances. The dislodgement of a tooth during this routine procedure is extremely rare and occurs almost exclusively when a tooth is already compromised or unstable.
How Dental Impressions Work
Physical impressions use a putty-like material, such as alginate or a vinyl polysiloxane (VPS) silicone, placed within a tray and seated over the dental arch. This material is designed to flow into every crevice and detail before setting into a firm, yet slightly flexible, mold. The material must capture the fine contours of the teeth, including the undercuts, which are the slight inward slopes near the gumline.
This necessity to capture detail means the material mechanically locks around the teeth. Once the material sets, the dentist must apply a quick, firm force to break this mechanical lock and remove the tray. This pulling force, combined with the material’s grip, generates the potential for dislodgement. For a tooth secured firmly by healthy bone and gum tissue, this force is not enough to cause movement or extraction.
Teeth Most Vulnerable to Dislodgement
Impressions do not pull out teeth that are fully integrated into the jawbone; rather, they reveal pre-existing instability. These compromised teeth are essentially hanging on by a thread, and the impression material’s grip is the final force that separates them from the mouth.
Primary Teeth
One of the most common categories of vulnerable teeth is primary, or “baby,” teeth that are in the final stages of exfoliation. These teeth have naturally lost most of their root structure as the permanent tooth pushes upward and are easily removed by the sticky impression material.
Periodontal Disease
Another major risk factor is advanced periodontal disease, often called gum disease, which causes significant bone loss around the root of the tooth. Mobile teeth with a high degree of movement, sometimes categorized as Grade III mobility, are particularly susceptible to being pulled out because their structural support is severely diminished.
Temporary Restorations
Temporary dental restorations, such as temporary crowns or bridges, also present a heightened risk of removal. These provisional devices are deliberately held in place with a temporary cement that is weaker than the permanent version. The impression material, especially high-viscosity putties, can lock tightly around the restoration’s margins, pulling it off the prepared tooth when the tray is removed.
Minimizing Risk and Patient Preparation
Preventative measures and open communication minimize the risk of unexpected dislodgement during the procedure. Patients should inform their dentist of any known issues, such as loose teeth, toothaches, or the presence of temporary crowns or bridges, before the impression is taken. This disclosure allows the dental team to adjust their technique accordingly.
The dental professional will assess the mobility of any questionable teeth before proceeding. Techniques to reduce the material’s grip include applying a thin layer of a release agent, such as petroleum jelly, to the teeth and temporary restorations. Dentists also carefully select impression materials; some, like flexible alginates, are less likely to grip an unstable tooth than stiffer materials. When removing the impression, a swift, practiced technique ensures the force is applied correctly and smoothly to break the mechanical lock without undue strain on the teeth.