Dahl effect

The Dahl effect or Dahl concept is a concept used in dentistry where changes are planned in the occlusion of the dentition. Dahl first described this phenomenon: a Dahl appliance uses an anterior bite plane to increase the available interocclusal space available for restorations.

It is of great interest to the dentist when an increase in the interocclusal space is required together with an increase in occlusal vertical dimension is required; for example when restoring a case of severe anterior tooth surface loss. Typically, restoring the worn anterior teeth with dental composite to the original proportions will result in an increase in OVD, with the posterior dentition held apart out of the occlusion.

Adaptation occurs over a period of some months: compensatory eruption of the posterior teeth will occur, together with some intrusion of the anterior teeth and potential growth of the alveolar bone. This will allow the posterior occlusion to reestablish at the new increased OVD, stabilizing the increased interocclusal space.

The advantages of this approach are: minimal removal of tooth substance is required to create the interocclusal space, lost OVD can be restored, minimising facial aging, it is a safe, relatively simple, relatively cheap approach in selected patients.

Risks of this approach to tooth surface loss cases are the risk that the patients tolerance and adaptive capacity might be exceeded. Planned occlusal changes can be tested using a removable appliance prior to permanent treatment. Dental composite based approaches to tooth surface loss allow for easy adjustment or removal if required.

References

• Smith BGN (1998). Planning and making crowns and bridges (3rd ed.). London: Routledge. p. 71. ISBN 978-0-203-41955-7. OCLC 60311365. 
• Poyser NJ, Porter RW, Briggs PF, Chana HS, Kelleher MG (June 2005). "The Dahl Concept: past, present and future". British Dental Journal 198 (11): 669–76; quiz 720. doi:10.1038/sj.bdj.4812371. PMID 15951771.