DentAI – The Alleman-Deliperi Rule and Biobase Impression

The Alleman-Deliperi Rule for the Biobase

• The thickness of the initial layers bonded to the tooth's dentin during the first 5 minutes should not exceed 1.5 mm.
• The layers that form the Biobase, placed during the first 5 minutes and being part of the Biobase, are as follows:
• Immediate Dentin Sealing (IDS)
• Resin Coating (RC) with a thickness of 0.5 mm
• Composite (fiber-reinforced) with a thickness of 1 mm

Impression in the indirect method of making a dental restoration

• Ideal method (recommended):
• Preparation
• IDS and RC
• Impression / scan
• Waiting for the restoration to be fabricated in the laboratory (during this time the hybrid layer matures and, over a long period until delivery, reaches its maximum strength)
• Fabricating the restoration and cementing it
• Advantages: High bond strength and greater durability of the restoration thanks to sufficient maturation of the hybrid layer.

Second method (non-ideal — DDS, or Delayed Dentin Sealing)

• Preparation
• Impression / scan
• Fabricating the restoration
• DDS (applying the bond to the dentin immediately before delivering the restoration)
• Cementing the restoration
• Disadvantages: Lower bond strength due to insufficient maturation of the hybrid layer.

If an impression is taken immediately after building the Biobase, the following are mandatory

• Using glycerin: To prevent the effects of oxygen inhibition.
• Removing residual resin from the enamel margins by performing appropriate finishing.
• Cleaning the Biobase with pumice: To remove contaminants (this step is performed when digital scanning is not used).
• The goal of these measures: To prevent interference between the impression material (especially PVS) and the resin.