Dental impressions are molds of a patient’s teeth and gums used to create custom-fitted dental appliances. These detailed replicas are used to fabricate items such as crowns, bridges, clear aligners, retainers, and dentures. The time spent with the material in your mouth is relatively brief. For a standard impression, the actual chair time for the molding is typically between 5 and 15 minutes.
The Time Breakdown for Traditional Impressions
The traditional method uses a viscous material placed in a U-shaped tray. This process requires a specific sequence of steps that contributes to the total chair time. The first step is selecting the correct size of the impression tray, which must fit the patient’s arch without impinging on the soft tissues. This preparation and fitting takes approximately 3 to 5 minutes.
Once the tray is selected, the impression material must be mixed and loaded, a swift process taking about 1 to 2 minutes. Materials like alginate or Vinyl Polysiloxane (PVS) are commonly used, and they begin to set quickly. The timing is precise because the material must be loaded and seated in the mouth before the chemical reaction progresses too far.
After the tray is seated over the dental arch, the patient must remain still while the material sets completely. This is the most time-sensitive part of the process. For PVS materials, the setting time can range from 2 to 5 minutes, depending on the material’s formulation. Alginate sets quickly, but the time in the mouth is managed to ensure a full capture of all necessary anatomical details.
The final step is the careful removal of the tray and the assessment of the finished mold. The entire physical process—from mixing to removal—typically falls into the 10 to 15-minute range for a single arch. While the material setting time is short, the preparation and assessment steps slightly extend the overall procedure in the dental chair.
Variables That Affect Impression Time
While 10 to 15 minutes represents the ideal time for a traditional impression, several factors can cause the appointment to take longer. Patient physiology, such as a strong gag reflex, is a common issue that can complicate the procedure. The physical presence of the tray and the impression material can trigger this reflex, requiring the clinician to pause, reposition, or even restart the process.
Excessive saliva production is another factor, as moisture can compromise the accuracy of certain impression materials like alginate. The dental team may need to spend extra time managing the saliva flow to ensure the material captures a clean, dry surface, which adds minutes to the total appointment time. If the mold is not perfectly clean, the entire procedure may need to be repeated.
Technical difficulties frequently lead to retakes, extending the time far beyond the initial estimate. Errors such as air bubbles, incomplete margins around the tooth preparation, or tears in the material require a full re-do of the impression. The complexity of the case also plays a role; a full-arch impression for a denture takes more time than a partial impression for a single crown. These variables mean an appointment should allow for unexpected delays, potentially pushing the total chair time to 20 minutes or more if a retake is necessary.
Digital Impressions A Faster Alternative
Digital impressions utilize intraoral scanners, offering a faster alternative to the traditional tray method. This technology uses a small wand to capture thousands of images per second, creating a three-dimensional model of the teeth and gums. The process eliminates the need for physical impression materials, mixing, and setting time.
A full-arch digital scan can often be completed in a fraction of the time required for a conventional impression. Depending on the specific scanner and the experience of the operator, scanning the entire mouth may take as little as 60 seconds, with many full-arch scans falling in the 3 to 7-minute range. This efficiency drastically reduces the patient’s time in the chair compared to the traditional process.
The primary advantage of the digital approach is the immediate visual feedback and quality assurance provided by the computer screen. The clinician can instantly assess the captured data for completeness and accuracy, identifying any missing information in real-time. This capability significantly reduces the chance of lengthy retakes common with physical molds.