Guidelines for a Good Impression

Making an accurate and detailed impression is the first and most important step in creating superior restorations for you patients. A good impression will have the following:

• Uniform, homogenous mix of material
• Tray is sufficiently filled with impression material
• Thoroughly applied tray adhesive
• No voids or pulls on margin detail
• Detailed margins with no tears or rough surfaces
• No tray show-through of the impression material
• Good blend between heavy body and light body materials
• Strong bond between impression material and tray
• No tooth contact with the tray

Bite Registration


Issue

• Difficulty in establishing vertical and horizontal relationships of the dental arches to the mounted stone casts

• Excessive occlusal adjustment


Cause

• Bite registration no provided



• Poor interocclusal record

Solution

• Provide a rigid and dimensionally stable bite registration with each case


• Excessive occlusal adjustment
• Use dimensionally stable bite registration material
• Ensure that the patient does not move during the procedure


Guidelines for Taking a Shade

• Take the shade and any photographs at the beginning of the appointment, this avoids eye fatigue
• Turn off the dental exam light
• Use colour corrected fluorescent lights in treatment rooms
• Use a neutral patient towel, blue or grey, never yellow
• Set the chair at 45° and view the patient at eye level and at arm’s length
• Be sure there are no shadows present
• Position the shade tab in the same plane as the teeth
• Squint eyes to use the cones of the eye, as the cones are better for value and colour than the rods that are being utilized more when not squinting
• After 10 seconds, look at grey or blue before trying another shade

Bite Registration


Issue

• Tight Crowns






• Short Crowns


Cause

• Early mouth removal
• Seating partially set impression material
• Poor bond of material to tray
• Insufficient tray support



• Teeth in contact with tray, not adequately relieving pre-set impression material
• Insufficient die trimming

Solution

•Closely follow product recommendation for oral setting time
• Closely follow product recommendation for oral working time
• Always use a VPS adhesive and allow to dry as per product instructions

• Use custom or inflexible (metal) stock trays
• Avoid contact of teeth with tray
• Consult with dental laboratory