What is the Dahl concept?
The Dahl concept is a method of treating the localised wear of anterior teeth, without having to treat the back teeth. This conservative method can be used to control incisal guidance and gain palatal space for restorative material. It is also a non-invasive, preventative treatment that can help eliminate the risk of full-mouth wear and the resulting need for rehabilitation.
The history of the Dahl concept
The concept was originally introduced in 1975 by Dahl, to create space in the treatment of anterior localised tooth wear. It involved the patient wearing a removable, chrome-cobalt appliance with an anterior bite plate to separate the back teeth.
Initially, the back teeth were discluded and, rather than using restorative methods to re-establish the posterior occlusion, it was allowed to re-establish itself over time.
According to Dahl, this was caused by a combination of the intrusion of the anterior teeth and the eruption of the posterior teeth. This process usually occurred over 4 to 6 months.
As updated techniques and materials become available, the concept was adapted to provide a useful tool for restorative dentistry. By increasing the Vertical Dimension of Occlusion (VDO), the incisal guidance angle can be reduced, creating a more favourable biomechanical situation.
When is the Dahl concept used?
The Dahl concept is traditionally associated with the management of worn teeth, with main applications being for localised anterior wear, resulting from factors such as bulimia and gastroesophageal reflux disease (GERD), which can result in severe dental erosion. This erosion often leaves insufficient interocclusal space to carry out adequate restoration.
However, it is worth noting that, today the principle can also be successfully applied in a range of clinical situations, helping to preserve tooth tissue in the long term.
Without the Dhal concept, the dentist would be required to reduce the occlusal height of the worn teeth further. However, this is not a favoured approach as it results in a lack of axial height, leading to insufficient retention and resistance for conventional extra-coronal restorations. Ultimately, this can risk damage to the tooth pulp, leaving limited options for future restoration replacement.
How does a Dahl appliance work?
The Dahl appliance is used to create space between the upper jaw and lower jaw.
Originally, the Dahl appliance was a removable metal bite platform, crafted from cobalt chromium. Today, many different materials and techniques can be used. Placing a Dahl composite resin appliance on worn down front teeth can help to separate and stimulate the eruption of the back teeth. Then, once the back teeth make contact, restorations can be carried out on the front teeth, without the need to remove significant amounts of tooth structure to accommodate them.
The benefits of the Dahl approach
The Dahl concept offers a range of benefits, including:
- Low cost
- Effective when used on any age group
- Reversible
- Safe
- Any lost occlusal vertical dimension (OVD) can be restored
- Limited destruction of tooth material
The success of the Dahl concept
According to literature on the subject, the Dahl concept achieves its objectives in the vast majority of cases, typically 94-100%. Unlike some other techniques, success is not impacted by the age or sex of the patient.
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