Golden Nuggets with Eileen Johnston

I remember as a young newly qualified dentist always checking my day list in practice and having that heart-sinking moment when I realised I was treating a young child with caries in his or her primary dentition.

How do you prepare yourself for the potential onslaught of anxieties, tears and every other emotion a young child can throw at you when faced with a dental visit, coupled with the parents’ fears and your own questioning conscience of how you’re going to restore that carious primary molar to the best of your ability? All of this whilst providing the child with a good experience and a one-off, predictable and durable restoration to allow natural exfoliation at the correct time!

When I was an undergraduate we were taught conventional restorative techniques using local anaesthetic, caries removal and restoration with amalgam, composite (if you were skilled enough to achieve isolation in a wriggling 5-year-old with limited access), and the conventional preformed metal crown (PMC) preparation.

These restorations absolutely have their successes—especially in the ideal cooperative child—but unfortunately a significant proportion of young children do not have that level of cooperation. Many have anxieties over the use of local anaesthetic, drills or suction, and so it was with the advent of the ‘Hall Technique’ that my own anxieties began to diminish. I could now see a way to treat a child, anxious or not. Utilising this simplistic yet skilled, noninvasive technique, I could achieve a predictable, durable result and have a happy child at the end of the visit.

The ‘Hall Technique’ was named after a general dental practitioner (GDP) Dr Norma Hall from Scotland, who simplified restoring a carious lesion on a primary molar by cementing a PMC without prior use of local anaesthesia, caries removal or tooth preparation.¹

The Hall Technique is described as a biological restoration—one that works by denying the bacteria in the carious cavity nutrients from the oral environment by sealing them into the tooth. This eliminates the ability of the carious lesion to progress toward the pulp.^2,3

Randomised controlled trials have found the Hall Technique as good as or better than comparable treatments with success rates of 97% over 5 years.⁴

As Evans and Innes state in their user manual,⁵ the Hall Technique is a useful and effective tool to have in our armamentarium for management of a carious primary molar. However, it is still underutilised in general practice despite being time-efficient and providing a greater remuneration in comparison to other conventional primary restorations.

To establish which carious primary molars are suitable for this technique, a full history, clinical examination and appropriate investigations including radiography (ideally bitewings) should be performed. Table 1 outlines the indications and contraindications for suitable case selection for the Hall Technique. Medically compromised children who are immunosuppressed or at risk of bacterial endocarditis should be referred for management by a consultant or specialist. The precooperative child who could challenge any skilled clinician at maintaining a safe patent airway may not be a candidate for this technique.

Appendix Table 1: indications and contraindications for using the Hall Technique

At the treatment planning stage and when discussing the various options available to manage a carious primary molar, the dentist should be prepared to ‘sell’ the technique. Don't be afraid to show the child the PMC; most children don’t mind the concept of a silver crown as they can see it either as their very own princess crown or Iron Man helmet and once you have the child on board, convincing the parent becomes easier. Like any dental procedure for a child, the dentist should explain it from beginning to end to prepare them for what’s going to happen. For children who require more information, you can show them the equipment and demonstrate the process on a tooth model.

The user manual⁵ advises that Hall crowns can be successfully placed to primary molars in contact with adjacent teeth as the periodontal ligament can absorb the displacement necessary to fit the crown. However, this depends upon the cooperation of the child to bite it into place, and often a young or anxious patient is not keen to get that involved. In such cases where there is no natural spacing, orthodontic separators can be used to provide space between the primary molars (Fig. 1). This allows easier placement of a PMC with greater precision for the dentist and a more comfortable experience for the child. The placement of separators takes no more than a few minutes and can either be placed using an orthodontic separator plier or two lengths of floss threaded through the separator (Figs. 2 and 3). This is then pulled taut and flossed through the contact point, leaving the superior half of the band above the contact point with the inferior half below (Fig. 1). The user manual5 advises they are left in situ for 3–5 days for the ideal amount of spacing to occur, but sufficient space has been noted 2–3 hours after placement.

Always check to ensure separators are in situ at the following visit or if the patient or parent is aware they've fallen out; occasionally they can work their way under a contact point. They can then be removed with either a straight probe or tweezers. With the space created, visual assessment of the shape and size of the tooth is easier. Before sizing a crown, the patient should be placed in a more upright position, with airway protection throughout to prevent inadvertent swallowing or inhalation. If marginal breakdown has occurred or teeth have migrated, you may have to adjust the tooth or the crown itself with orthodontic band forming pliers. In most cases, minimal adjustment is required due to the precontoured, pretrimmed and crimped PMCs available. Select the smallest crown that provides cuspal coverage and approaches the contact points with a slight spring-back.⁵ This is of particular importance for the second primary molars, especially in the maxilla before the eruption of the first permanent molar. It’s important to monitor their eruption to ensure there’s no impaction against the crown margin. Refrain from fully seating the crown before cementation because it can be difficult to remove and require the use of an excavator or a high-speed turbine. Once you've chosen the best fit, dry and fill with an appropriate luting cement such as glass ionomer and fully seat the crown over the tooth by applying finger pressure or by getting the child to bite the crown into place, with a cotton wool roll placed over the crown. Excess cement should then be removed with either cotton wool or gauze, and the child should then again bite upon the crown until the cement is fully set to avoid spring back, which could potentially create a breach in the seal.⁵ Remove any further excess and floss between the contacts. For some patients taste can be an issue and therefore toothpaste can be used after placement as a distraction.

Lower second primary molars are the easiest to begin with due to their singular contact point (i.e., before the eruption of the first permanent molar), direct vision and the ability for good isolation and airway management.

Two crowns can be fitted at the same appointment, but these must be on either side of the same arch (Fig. 4) or diagonally opposite in different arches. It is recommended not to fit crowns on opposing teeth at the same time because the temporary occlusal interference is exacerbated and it is usually difficult to fit two Hall crowns in the same quadrant.⁵

Finally, check the degree of occlusal discrepancy; most children will accommodate some change without symptoms and the occlusal equilibrium will re-establish within a few weeks.

Despite reviews demonstrating that the Hall Technique is well-tolerated by children, some children are still anxious regarding this treatment modality and therefore behavioural management and distraction are often required. Cognitive behavioural therapy techniques like desensitisation work well. For example, you can demonstrate the whole process on a tooth model or floss the separator between two fingers, let them feel the cement on their hand or squish it between their fingers—you can even let them taste the cement before its use so they know what to expect. Including children in the decision-making process also helps; ask them to see what friends have crowns and how they found the treatment. Let them be interactive throughout the treatment session by assisting you—holding the cotton wool roll, guessing the size of the crown, etc. Younger children may like to name their crown to make it more personal to them. The use of topical anaesthetic placed on the surrounding gingivae of the carious molar allows placement of the PMC with limited discomfort upon finger pressure or biting into place. Distraction by a favourite TV programme or video on a parents’ phone whilst your working produces a cooperative child who is no longer fixated on the dental treatment but getting to do something that they enjoy. Finally, for any dentist trained in hypnosis, the magic glove technique works exceptionally well.

It is appreciated that many parents are not keen on the aesthetics of a PMC and the use of aesthetic white crowns for children's teeth is of growing interest, but they are not commonly used yet because they are not available on the NHS. The Cochrane review⁶

advises that it is unlikely for a white crown to be able to be placed using the noninvasive Hall Technique. This is due to their rigid properties, with no ability for distortion upon pushing over the bulbosity of a primary molar. During current times the only way to provide an aesthetically pleasing result would be to carry out a traditional crown preparation with local anaesthetic to accommodate the thickness of composite facing material or allow a passive fit to avoid adjustments.^{3, 7}

As GDPs we are all faced with the technical demands of children’s dentistry—their limited access with small and challenging morphology of their primary dentition often coupled with anxieties. In my opinion, the Hall technique has revolutionised children’s dentistry not only for children but also for parents and clinicians. It allows teeth to be restored in a more simplistic, biological manner with a predictable restoration which the child readily accepts. Randomised clinical trials demonstrate that PMCs outperform other restorative techniques, providing a durable solution less likely to develop problems or cause pain in the long term.

I would urge any GDP to try the technique with a carefully selected number of cases in cooperative children who require their primary molars to be restored. As with any new skill, a little bit of practice will allow you to gain experience in the correct sizing of PMCs and your technique will continually refine with each crown placed.

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References
1. Innes NPT, Evans DJP Modern approaches to caries management of the primary dentition. Br Dent J 2013; 214, 559-556
2. Welbury RR, The Hall technique 10 years on: Its effect and influence. Br Dent J 2017; 222, 421-422
3. Innes NPT et al The Hall technique 10 years on: Questions and answers. Br Dent J 2017; 222, 478-483
4. Innes NP, Evans DJ, Stirrups DR Sealing caries in primary molars: a randomised control trial, 5-years results J Dent Res 2011; 90:1405-1410
5. The Hall Technique. A minimal intervention, child centred approach to managing the carious primary molar. A Users Manual. (Edition 3) 11.11.10. University of Dundee. D.Evans & N.Innes. https://dentistry.dundee.ac.uk/files/3M_93C%20HallTechGuide2191110.pdf (accessed 14/4/17)
6. Innes NPT, et al Preformed crowns for decayed primary molar teeth Cochrane Database Syst Review 2015;12: CD005512
7. A.C. O'Connell, E. Kratunova Prefrabicated crowns for primary molars. http://sdmag.co.uk/2016/02/01/prefabricated-crowns-for-primary-molars (accessed 14/4/17)

Eileen Johnston BSc (Hons), BDS, MFDS RCSEd qualified from Glasgow University dental school in 2004 and has worked within general practice and the Public Dental Service (PDS) in both the Lothian and Greater Glasgow areas. She is currently working as a PDS Dental Officer within the paediatric service of Greater Glasgow and Clyde. She has special interests in paediatric dentistry and anxiety management. She has completed her training in cognitive behavioural techniques for treatment of dental fear at Kings College London and the Medical and Dental hypnotherapy training with BSMDH Scotland.