Use of the 'Hall technique' for management of carious primary molars among Scottish general dental practitioners.
Abstract: AIM: To assess the current awareness, usage and opinion of the Hall technique as a restorative option for primary molars in Scottish general dental practice; and to identify preferences for methods of further training, if desired, for those not currently using the technique. STUDY DESIGN: A postal questionnaire was sent to a random sample of Scottish general dental practitioners (GDPs) (n= 1207). Half of all GDPs within each health board were contacted. All analyses were carried out in Minitab (version 15). The study was primarily descriptive and used frequency distributions and cross-tabulations. Percentages are reported with p5% confidence intervals. Characteristics of the whole sample were reported. However when recording the use of the Hall technique, only those GDP's reporting to treat children, at least sometimes, are considered. RESULTS: Following two mail-shots, the overall response rate was 59% (715/1207). Eighty-six percent (616/715) of respondents were aware of the Hall technique as a method of restoring primary molars and 48 % (n=318) were currently using the Hall technique. Of those GDPs who never used the Hall technique (51% of total respondents; n=340), 46% (n=157) indicated they were either 'very interested' or 'interested' in adopting the Hall technique into their clinical practice. The preferred source for further training was via a section 63 continuing professional development (CPD) course, incorporating a practical element. CONCLUSIONS: Of those GDPs in Scotland who responded to the questionnaire, an unexpectedly high number were already using the Hall technique in their practice, and among those not currently using it, there is a demand for training.

Key words: : Hall technique, preformed metal crowns, caries, primary molars, general dental practitioners.
Article Type: Report
Subject: Dental caries (Care and treatment)
Dentists (Practice)
Molars (Physiological aspects)
Molars (Research)
Authors: Dean, A.A.
Bark, J.E.
Sherriff, A.
Macpherson, L.M.D.
Cairns, A.M.
Pub Date: 06/01/2011
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2011 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: June, 2011 Source Volume: 12 Source Issue: 3
Topic: Event Code: 200 Management dynamics; 310 Science & research
Product: Product Code: 8021000 Dentists NAICS Code: 62121 Offices of Dentists
Geographic: Geographic Scope: Scotland Geographic Code: 4EUUS Scotland
Accession Number: 277106761
Full Text: Introduction and Background

Today, in Scotland, there is still a worryingly high prevalence of dental caries in the primary dentition. According to the most recent statistics available, 42.3% of primary school children in Scotland have obvious dental caries (d3 level), rising to 58% in the most deprived areas [NDIP, 2008]. Conventional and recommended methods of managing childhood caries include restoration with amalgam or composite resin [SIGN, 2000], or where indicated by either clinical or behavioural criteria and extraction under general dental anaesthesia (DGA) [Macpherson et al., 2005]. Scotland, in particular, continues to have the highest rate of DGA in Europe. However, in a recently published Scottish dental clinical effectiveness programme (SDCEP) guideline; 'The prevention and management of dental caries in children' [SDCEP, 2010], detailed methods for sealing in caries are described, the Hall technique being one of these. The Hall technique manages carious primary molars without caries removal or tooth preparation; caries is hermetically sealed within the tooth by a preformed metal crown (PMC) cemented with glass ionomer cement (Fig 1). This process arrests the carious lesion with the intention of preserving the tooth until exfoliation. Its biological principles are very straightforward [Ricketts et al., 2006] and a comprehensive manual on the technique is available online, prepared by paediatric dentists at Dundee dental hospital and school [Innes and Evans, 2006].


The Hall technique is designed to increase patient compliance and operator ease as local anaesthetic is not used. In addition to sealing in caries, it is hoped that a child having a less traumatic experience of dentistry early in life means they are more likely to return for more complex treatment later in life; this is a widely accepted premise [Liddell and Locker, 2000].

In 2007, a randomised controlled trial was undertaken in Tayside, Scotland, to compare the outcome of molars restored using the Hall technique with that of molars restored with conventional restorations [Innes et al., 2007]. The results were significantly in favour of the Hall technique; with better outcomes for pulpal health and longevity of the restoration.

At present there are no data available on GDP's usage of the technique but recent research carried out by the authors would suggest that it is gaining favour amongst Scottish specialists in paediatric dentistry [Bark et al., 2009]. At present it does however remain a controversial technique and letters regarding it have appeared in the British Dental Journal [Roberts and Attari, 2006; Murphy, 2008].

In light of this, the aim of the present study was to assess the current awareness, usage and opinion of the Hall technique as a restorative option for primary molars in Scottish general dental practice; and to identify preferences for methods of further training, if desired, for those not currently using the technique.

Materials and Methods

The study population. A postal questionnaire was sent to half of all Scottish GDPs within each of the health boards (n= 1207). Assuming a response rate of 75%, the study would have 80% precision to estimate prevalence of use of the Hall technique to within +/- 2% [Naing et al., 2006].

Sample selection. All GDPs in Scotland were listed by health board alphabetically and every second GDP was sent a questionnaire. This provided an unbiased selection system which also inevitably gave an accurate representation from each Health Board.

Ethical approval. Communication between NRES (National Research Ethics Service) and the university of Glasgow ethics faculty advisor concluded that formal ethical approval was not required.

The questionnaire. The questionnaire contained 17 questions including requests for demographic data. All questionnaires were sent out with an accompanying cover letter. Addresses for the GDP's were obtained from an internet directory and statistics on GDP numbers per health board from colleagues in dental public health.

The questionnaire was mainly of a 'tick-box' closed question format to minimise any errors and to make it more user-friendly. GDP's were asked to expand on why they had responded yes or no to a particular question. This was of an open question format with space for free text. Space was also made available for additional comments. The questionnaire was piloted on ten visiting GDPs at Glasgow Dental Hospital and School and slight modifications were made following feedback. The questionnaire was designed to answer the following questions:

* What is the current level of awareness and usage of the Hall technique in Scottish general dental practice?

* How often is the technique used and what is the opinion of it amongst GDPs who have used it?

* If it is not used in general dental practice, why not?

* How interested are those not using it in adopting it into their practice?

* Is training in this area desired, and if so, what format would the GDPs like this to be in?

The questionnaires were dispatched along with a pre-paid addressed envelope.

Data input. The data was processed using a minitab database. Anonymous coding allowed for a second mail shot to be sent to all initial non-respondents. All analyses were carried out in minitab (version 15). The study is primarily descriptive and used frequency distributions and cross-tabulations.

Percentages are reported with p=<0.05 confidence intervals. Characteristics of the whole sample were reported. However when reporting the use of the Hall technique, only those GDP's reporting to treat children, at least sometimes, were considered (n=665).


As all respondents did not answer every question, total numbers responding to each question varied.

General and demographic data. The first mail-shot (n=1,207) received a response rate of 45.6% (n= 550). By utilising a blinded coding system, a second mail-shot was sent to all non-responders (n= 657) which achieved a response rate of 25.1% (n= 165). On removal of those respondents who could not be included in the study (GDPs currently not practising e.g. for maternity leave n= 7) the overall response rate (both mailings) was 59.6% (n=715). The characteristics of the study sample are displayed in Table 1.

Use of Hall technique. A high proportion of respondents who treated children (86%, n=665) stated they had heard of the Hall technique, with 48% indicating that they currently use the technique (n=318). As indicated in Figure 2 the frequency of use varied from 'never' (n=340) to 'very frequently' (n=25).


Opinion of Hall technique. Of the GDPs who stated they very occasionally used the Hall technique (18.8% of respondents who treat children, n= 125), the greatest proportion (44.7% n= 55) indicated they sometimes found the technique effective. The majority of GDPs using the technique 'sometimes' or 'frequently' (35.8% (n=114) and 15.9% (n=53) of total respondents respectively) found the technique frequently effective (50.9% (n= 58) and 60.4% (n=32) respectively). Of those who used the technique 'very frequently' (7.9% n=25); the vast majority (88% n= 22) found it very frequently effective. This trend indicated that the more a GDP used the technique the more effective they consider it to be.

Previous training. Of the respondents 93.3% (n=665) were aware of the existence of the Hall technique and that most of this knowledge had been obtained post-qualification, 77% (n=550). Most of this knowledge had been obtained via dental journals, 53% (n=379) or word of mouth, 5% (n=38) although others had attended postgraduate courses, 18.6% (n=133). Some dentists had undergraduate training in the technique, but only 16% (n=115).

Barriers against use of Hall technique. For those GDPs who indicated they never used the Hall technique, a lack of confidence and/or knowledge was clearly the main barrier against its use (26%). Lack of stock materials (8%) and a preference for alternative treatment (8%) followed as other barriers.

Interest in Hall technique and further training preferences. Of those GDPs who stated they never used the Hall technique, 52.9% (n=176) indicated they were either 'very interested' or 'interested' in introducing the Hall technique into their clinical practice, and 10.2% (n=34) were 'not interested at all'.

All of the GDPs were asked how they would like to increase their knowledge or training in the Hall technique if desired. GDPs tended to indicate more than one choice, however it was clear that practical-based government funded continuing education courses were a preferred option (299 GDPs indicated this); followed by a DVD training program (172 GDPs) and a hard copy of the manual sent to them (132 GDPs). Other options included an online training manual (88 GDPs) or a lecture-based postgraduate course (84 GDPs).

The GDPs not already using the technique (n=392) were also asked to consider whether an introductory set of preformed metal crowns (PMCs) at a reduced cost would increase their likelihood of trying the technique. Of the GDPs that responded 68.2% (n=208) indicated it would, and 31.8% said it would not (37 did not indicate a choice).


The results were certainly surprising to the investigators, indicating that 48.1% of the Scottish GDP population are currently using the Hall technique. A substantial (93.3%) proportion of the GDPs had heard of the technique. Knowledge of the technique amongst GDPs was gained predominantly through postgraduate education; however journals, recent undergraduate training and word of mouth also proved significant sources of knowledge.

An interesting result was that of those GDP respondents who stated they never used the Hall technique, 52.9% (n=176) indicated they were either 'very interested' or 'interested' in adopting the Hall technique into their clinical practice. In terms of training options, it was clear that a practical-based postgraduate course was the preferred option followed by a DVD training program and a hard copy of the manual sent to them.

The study selected GDPs using a stratified sampling system giving a proportionate representation of dentists from each health board. The respondents varied vastly in years since qualification, which is to be expected: 2.3% of respondents had graduated for less than two years, and 41.7% of respondents had graduated over 20 years ago. Although the representation is small for the newly qualified, a trend between years since qualification and use of the technique can be identified. Of those who had graduated less than 2 years previously 62.5% are using the technique compared to 44.6% of those who had been graduated for over 20 years.

The GDPs who used the technique were asked if they found the technique effective: unsurprisingly, the results clearly displayed that those GDPs who used the technique more frequently found it more effective and vice-versa. The suggestion from this result is that that once the practitioner is confident in the technique through further training or experience, he or she will achieve success more often with the technique; possibly by exercising better patient selection or by improving operator skills. It should however be reported that we did not give the GDPs any criteria with which to measure 'effectiveness' so this was left open to individual interpretation.

For those who stated they never used the technique; it was clear that a lack of confidence and knowledge of the method were the main reasons why they did not use it. Other reasons included availability of stock materials; that they felt another treatment option was more appropriate and also the belief that it is a costly treatment option. The financial aspect as a reason for not choosing this treatment option is interesting, as the Scottish dental regulations [NHS PCC Directorate, 2009] stipulate that a GDP can claim 20.69 [pounds sterling] (24 [euro]) for a PMC restoration, as opposed to 7.87 [pounds sterling] (9 [euro]) for a standard restoration. According to the clinical trial carried out in Tayside [Innes et al., 2007] Hall technique restorations are much less likely to require replacement than conventional restorations and so theoretically should save valuable clinical time in the long-term (in addition to the patient having to spend less time in the dental chair). This re-enforces previous research which has shown conventional PMCs to also have superior longevity than conventional restorations [Randall et al., 2000]. The nature of the technique should also minimise the materials required (e.g. local analgesics, burs etc). The outlay costs, however, are clearly another potential barrier to its use, and when asked if a reduced cost introductory set of PMC would increase likelihood of trying the technique, 68.2% (n=208) indicated it would.

Finally, the dentists were asked for their subjective opinions on the technique. Positively, the technique was praised for its restoration longevity, the little preparation required and also in some cases that procedure time was decreased. Drawbacks frequently included the belief that occlusal complications may arise due to a sudden increase in overall vertical dimension (OVD). However, the initial study of the technique in Tayside [Innes et al., 2007] found that no child or parent reported difficulty with eating or symptoms of temporomandibular joint dysfunction syndrome at one year or at two year recall appointments. They also importantly noted that orthodontists routinely use bite planes which increase the OVD significantly more than the Hall crown would. One GDP mentioned that autistic children may not be suitable due to this change in occlusion and this is an important point which certainly should be addressed at the case selection stage. GDPs also stated that the poor aesthetics were a drawback as parents often refused the treatment purely because of this. Currently there is no available research which addresses this; it is most likely however that the child and parents views on the appearance of the crowns could be very much swayed by the GDPs explanation of the technique and its benefits. Certainly in the authors experience the children are mostly always content with their 'silver tooth'. Some GDPs also believe that the fitting of the crown would prove difficult, and some felt the tooth may still abscess. These are acceptable points however as mentioned before, the clinical trial already undertaken [Innes et al., 2007] showed the Hall technique had more favourable outcomes for pulpal health than for conventional restorations. We should note however that this study had stringent inclusion criteria which may not have been as rigorously adopted by the GDP population.


An unexpectedly high number of GDP's are already using the Hall Technique in their practice, and in those not currently using it there is a significant demand for training.


Bark JE, Dean AA, Cairns AM. Opinion and usage of the 'Hall technique' amongst paediatric dental specialists in Scotland. Int J Paediatr Dent 2009;19(Suppl. 2);11.

Innes N, Evans DJP. The Hall technique: A Users Manual 2006 (Version 2--December 2009). Access at

Innes NPT, Evans DJP, Stirrups DR. The Hall technique; a randomised controlled clinical trial of a novel method of managing carious primary molars in general dental practice: acceptability of the technique and outcomes at 23 months. BMC Oral Health 2007;7:18.

Liddell A, Locker D. Changes in levels of dental anxiety as a function of dental experience. Behav Modif 2000;24:57.

Macpherson LM, Pine CM, Tochel C et al. Factors influencing referral of children for dental extractions under general and local anaesthesia. Community Dent Health 2005; 22:282-288.

Murphy JP. Letters: The Hall technique. Brit Dent J 2008; 204:476.

Naing L, Winn T, Rusli BN. Practical issues in calculating the sample size for prevalence studies. Arch Orofacial Sci 2006;1:9-14.

NDIP, 2008. Scottish National Dental Inspection Programme.

NHS Primary and Community Care Directorate, 2009. Statement of Dental Renumeration. Access at

Randall RC, Vrijhoef MA, Wilson NHF. Efficacy of preformed metal crowns vs amalgam restorations in primary molars; a systematic review. J Am Dent Assoc 2000;31:337-343.

Ricketts DN , Kidd EA, Innes N et al. Complete or ultraconservative removal of decayed tissue in unfilled teeth. Cochrane Database Syst Rev 2006;3:CD003808.

Roberts JF, Attari N. Letters: The wide gulf. Brit Dent J 2006;200: 600-601

Scottish Dental Clinical Effectiveness Programme 2010. The prevention and management of dental caries in children. Access at www.scottishdental. org/cep.

Scottish Intercollegiate Guidelines Network, 2000. Publication No. 47: Preventing dental caries in children at high caries risk: Targeted prevention of dental caries in the permanent teeth of 6-16 year olds presenting for dental care.

A.A. Dean, J.E. Bark, A. Sherriff, L.M.D. Macpherson, A.M. Cairns

Department of Paediatric Dentistry, University of Glasgow Dental School, Glasgow, Scotland

Postal address: Dr A.M. Cairns Dept Paediatric Dentistry, Glasgow Dental Hospital and School. 378 Sauchiehall Street, Glasgow, G2 3JZ.

Table 1. Characteristics of Study Sample

Respondents       Ayrshire & Arran 6.4%   Borders 1.8% of
per Health        of respondents (n=45)   respondents (n=13)
Board             Total number GDPs in    Total number GDPs in
                  HB=173 therefore 26%    HB=47 therefore 28%
                  response from board     response from board

                  Dumfries and            Fife 7.6% of
                  Galloway 3.0% of        respondents (n=54)
                  respondents(n=21)       Total number GDPs in
                  Total number GDPs in    HB=184 (29%)
                  HB=65 (32%)

                  Forth Valley 4.5% of    Grampian 9.2% of
                  respondents (n=32)      respondents (n=65)
                  Total number GDPs in    Total number GDPs in
                  HB=131 (24%)            HB=212 (31%)

                  Greater Glasgow and     Highland 6.6% of
                  Clyde of respondents    respondents (n=47)
                  25.4% (n=180)           Total number GDPs in
                  Total number GDPs in    HB=139 (34%)
                  HB=732 (25%)

                  Lanarkshire 9.6% of     Lothian 15.1% of
                  respondents (n=68)      respondents (n=107)
                  Total number GDPs in    Total number GDPs in
                  HB=237 (29%)            HB=459 (23%)

                  Orkney 0.6% of          Shetland 0.6% of
                  respondents (n=4)       respondents (n=4)
                  Total number GDPs in    Total number GDPs in
                  HB=26 (15%)             HB=21 (19%)

                  Tayside 8.8% of         Western Isles 0.9% of
                  respondents (n=62)      respondents (n=6)
                  Total number GDPs in    Total number GDPs in
                  HB=225 (28%)            HB=16 (38%)

                  Not specified n=7

Working           Independent NHS GDP     84.0% (n=589)
                  Salaried NHS GDP        15.0% (n=103)

                  Other                   1.0% (n=7)

                  Not specified           n=14

Years Qualified   < 2 years               2.3% (n=16)

                  2- <5                   13.3% (n=94)

                  5- <10                  16.1% (n=114)

                  10- <20                 26.7% (n=189)

                  20+                     41.7% (n=295)

                  Not specified           n=7

Treat Children?   Never                   0.7% (n=5)

                  Very Occasionally       6.4% (n=45)

                  Sometimes               17.2% (n=122)

                  Frequently              52.9% (n=375)

                  Very Frequently         22.9% (n=162)

                  Not specified           n=6
Gale Copyright: Copyright 2011 Gale, Cengage Learning. All rights reserved.