Making an accurate and detailed impression is the first and most important step in creating superior prosthetic restorations for your patients. The main reason clinicians encounter crowns not seating, high/low occlusion or inadequate inter-proximal contacts is due to poor impressions. Success in Dentistry is mainly dependent on doing the fundamentals well. Here are a number of guides and tips on how to avoid common problems. The following list shows some of the most frequent occurring impression-taking issues, their possible causes, and tips to avoid them. Use these tips to avoid costly remakes or adjustments to your restorations.
Prep Design: Always start with the end goal in mind. If a patient shows heavy Bruxism prepping conservatively and requesting an Empress Crown for example might not be the best idea. Think of the final outcome before a bur touches the tooth and prep accordingly. Ask your Viva Dental Lab Technician/Representative for prepping protocols for different materials available in the market.
Soft Tissue Management: You need Hemostats and Retraction. You must be careful not to induce irreversible damage to tooth ligaments but retracting tissue is the only way to ensure margins are captured and visible on a model from its impression. According to most experienced clinicians, double cord retraction technique is the best way to displace tissue for an adequate impression. As secondary means of retraction, you can also use retraction paste and lasers but they are no match to double-cord technique. When heavy bleeding occurs, you might have to combine techniqu
es for proper hemostasis and retraction.
Impression Trays: Full arch trays are always preferred as the laboratory can manipulate models for lateral movements and avoid interferences better than using quadrant models. Triple trays are acceptable when doing single tooth cases but we advice against them on free end situations and cases over two units.
Impression Materials: Always use materials that have not exceeded their expiration dates and have been stored under the right temperature and humidity. Never mix fast set and regular set materials, and always use timers. PVS materials are preferred, as they remain stable for long periods of time. Key elements that your impression material should have include: dimensional accuracy, high reproduction of detail, wettability, and good resistance to deformation, high tear strength and adequate dimensional stability.