The Hall Technique is a relatively new approach to managing carious lesions in the primary dentition. Developed and used by Dr.Norna Hall until her retirement in 2006, the use of preformed metal crowns on primary teeth has become increasingly commonplace since favourable outcomes from retrospective analysis.
This article is a summary of the clinical procedure adpated from “The Hall Technique: A minimal intervention and child friendly approach to managing the carious primary molar; A Users Manual.” written by Nicola Innes and Dafydd Evans of the University of Dundee. The full PDF file is available for download.
The premise of the Hall Technique is based upon being able to change the cariogenicity of plaque by changing its environment. In a sheltered, non-favourable environment, cariogenic bacteria will fail to flourish. A well sealed Stainless Steel Crown is one method of affecting that change in environment for primary molar teeth.
Advantages of this technique include:
- No caries removal,
- No local anaesthesia,
- No Tooth Preparation.
To achieve success; case selection, clinical skill and excellent patient management are paramount. The Hall Technique should not be adopted as a “quick fix” and should always be part of an effective preventative treatment plan. The following are a summary of the indications and contraindications for this procedure.
- Proximal (Class II) lesions, cavitated or non-cavitated
- Occlusal (Class I) lesions, non cavitated if the patient is unable to accept a fissure sealant, partial caries removal or conventional restoration.
- Occlusal (class I lesions, cavitated if the patient is unable to accept partial caries removal technique or a conventional restoration.
- Signs or symptoms of irreversible pulpitis, or dental sepsis
- Clinical or radiographic signs of pulpal involvement, or periradicular pathology
- Crowns that are so broken down they would be considered unrestorable with conventional techniques
- Where a patient is at risk from bacterial endocarditis, or who is immunocompromised
It may be necessary to fit orthodontic separators at the mesial and distal contact points of the tooth to be crowned. This would provide the necessary space to fit the crown if the contacts are too tight. The patient will need to be seen within the week for crown fit.
Important to note:The separator should be “half-visible” occlusally,(see picture above) meaning only one part of the band is flossed through the contact point. This prevents the separator from becoming submerged in the gingivae, and also prevents losing the separator through the interproximal space.
Protecting the Airway
It is important to protect the child’s airway, especially when sizing the crown before cementation. This can be done with a square of gauze between the tooth and the tongue, extending to the palate and behind the fauces, to prevent any accidents. Note: If you are not confident of controlling the crown at all stages up until cementation, do not use this technique
Fitting the Crown
Try on crowns until one is seen to cover the occlusal table of the tooth but not impinge on the teeth on either side and there is a feeling of “spring back”.
The glass ionomer is mixed to the consistency of a regular crown luting cement (a thick paste). Load crown generously (it should be almost full with cement). Take care fill the crown from the base upwards and ensure that there is cement around the walls. Be careful to avoid air blows
3. Locate and seat
Some glass ionomer may be wiped on the tooth or placed in any cavitation to improve the seal. The crown is placed evenly over the tooth and engaged in the approximal contact points using finger pressure to secure its position. The child then bites down on the crown. Some operators find biting on a cotton wool roll helps the process.Care is taken to ensure the crown seats evenly over the tooth.
As soon as the crown is fitted, the child should be asked to open to allow the crown position to be checked and excess glass ionomer can be wiped away.
5. Seat further
When you are satisfied that the crown is in the optimal position, and whilst the cement is still soft, the child should be instructed to bite down again on the crown or cotton wool. It is likely that some more glass ionomer will be extruded. The child should keep pressure on until the cement has set, this prevents the crown from rising back up.
6. Check and clean
The fit of the crown should be checked. Excess cement can be wiped away whilst wet or a hand excavator used when dry. Dental floss should be used to clear the contacts of any
excess. Blanching usually disappears within minute. The occlusal discrepancy should resolve in a few weeks.
If the crown does not seat sufficiently, then remove it using the excavator before the cement sets. If the cement has set, a high speed handpiece can be used to section the crown through the buccal and occlusal surface, following which it can easily be peeled off and remaining cement trimmed as necessary.
Crowns will try to follow the path of least resistance, and so may tilt towards the
“easier” of the contacts, making it almost impossible then to ease the crown through
the tight contact. Concentrate on seating the crown through the tight contact, and the
easy one should take care of itself.
Reassure the parent and patient that it should normally feel normal again after 24 hours. There will be even contacts again within weeks. Note: You should allow 3 months for occlusal equilibration before fitting opposing teeth with Hall Crowns.
Patients should be reviewed on a normal recall schedule, and the Hall Technique
should be used in conjunction with a full preventive programme.
If fitting crowns to Es, particularly maxillary Es, before the 6s are erupted, keep an eye out for the 6s becoming impacted against the crown margin as they erupt. This can occur even if crowns
haven’t been fitted, and there is no evidence that there is an increased risk of this. Nevertheless, if
it does occur, it can often be managed with orthodontic separators if detected early.
If a molar fitted with Hall crown becomes non-vital, a pulpotomy can be carried out through the crown without needing to remove it.
Illustrations and text adapted from “The Hall Technique: A minimal intervention and child friendly approach to managing the carious primary molar; A Users Manual.” written by Nicola Innes and Dafydd Evans of the University of Dundee. Full text available to download here