Tooth

*Paediatric Dentistry, Division of Child Dental Health, Department of Oral and Dental Science, University of Bristol, Bristol, # Medical Statistician, Unit of Paediatric and Perinatal Epidemiology, Tyndall Avenue, Bristol, UK

Introduction

Materials and methods

Local anaesthesia is used routinely in dental surgery; it is effective in both pain control and - through the vasoconstrictors often contained within it - the reduction of bleeding. The extraction of deciduous teeth under general anaesthesia is often carried out without these local effects. There are no previous studies to investigate the combined effect of local anaesthesia with general anaesthesia on blood loss and pain control. A randomised, controlled clinical trial was carried out with one hundred children aged 3-5 years. Ethical approval and informed consent were obtained. Surface anaesthetic cream (EMLA) was placed on the hand into which the intravenous access was to be placed. One to two ml of blood was taken at the time of induction as a baseline of the patient’s level of haematin pigment. Children in the experimental group were given one quarter of a cartridge (0.5 ml) of local anaesthetic containing epinephrine (1:80,000) in each quadrant before tooth extraction; all blood in swabs, suction equipment and disposables was collected and digested with NaOH. The children were observed for 11 minutes post-operatively for any signs of distress. Total blood loss was calculated by comparison of the baseline sample and the shed blood digests. This study showed that using local anaesthesia for dental extractions under general anaesthesia was associated with decreased blood loss (p = 0.001). The second finding - which has not been reported before - was that this use of local anaesthesia was shown to cause distress to this age group of children upon recovery from the general anaesthetic (p <0.0001). The use of local anaesthetic in this situation provided a useful reduction in post-operative bleeding. However, its use was associated with greater post-operative distress.

Tooth removal is an unpleasant experience for the child, with implications of pain, blood loss and distress. General anaesthesia is often used for tooth removal in childhood in the United Kingdom and all of these procedures carry risks in terms of morbidity or even mortality.

Amongst the risks of morbidity are bleeding, post-operative pain and distress leading to subsequent aversion to dental or medical care.¹

Henderson et al (1997) quantified the bleeding that might be expected following tooth-loss under general anaesthesia.2 Various authors have devised methods to attempt to score the level of pain or distress experienced by children recovering from surgical procedures. ^3-5

Although the use of local analgesia administered during general anaesthesia for post-operative pain control is a widespread procedure and has been investigated as a haemostatic adjunct in third molar surgery, there would seem to be no previous study to investigate either its use as a post-operative analgesic, or its role in the control of post-extraction bleeding in children.⁶

The study employed the method previously utilised by Henderson et al (1997), to assess blood loss and the Toddler-Pre-schooler Postoperative Pain Score (TPPPS).⁵ Ethical approval was sought and obtained from the local Research Ethics Committee.

Following discussion and extensive consultation, prior agreement of the six staff operators and Anaesthetists (Consultants) was obtained. One hundred children aged 3-5 years who were deemed to be without significant medical history and who were attending the General Anaesthetic Department of the Dental Hospital for the removal of primary teeth were included in the study. The purpose and details of the study were explained in detail and informed parental consent was obtained, following the issue and discussion of an information sheet, in each case. An additional five parents refused for their children to be entered into the study, one where the child had already had a number of other general anaesthetics and the remainder because of parental apprehension, which could not be allayed.

Children were randomly allocated to either the control or the trial (local analgesia) group. Explanation was made to the child of the sensations to be expected post-operatively either with or without local analgesia.

For each child, topical surface analgesic cream (EMLA) was placed at the expected site of intended intra-venous access. At the time of induction, 1-2 ml of venous blood was drawn from this access before the administration of any saline or anaesthetic agent. Where intravenous access was not straightforward, the canula was placed once anaesthesia had been gained and was then flushed through with saline. The first aliquot of blood drawn was discarded and a second, uncontaminated sample taken. General anaesthesia followed standard practice with full monitoring of the unconscious child.

For the trial group, 0.5 ml of lignocaine 2% with 1:80,000 epinephrine was administered by local infiltration in each quadrant requiring extractions. The extractions were performed soon afterwards and immediate post-operative swabs placed as routine. All swabs and aspirated secretions were collected once each patient had fully recovered and clinical haemostasis had been obtained. The identity of teeth extracted was recorded. Cases requiring muco-gingival surgery, suturing, or which otherwise deviated from the standard procedure were excluded from the study.

A record was made of the identity of the principal (staff) operator for each patient.

During recovery, each child was observed over a period of 11 minutes (at one minute, 5-6 minutes and 10-11 minutes) by one researcher (S A-B) following repeated pilot runs in the presence of experienced recovery nurses to agree scoring.

Assessment of pain and distress was made using the TPPPS system. The TPPPS ‘distress score’, as described by Tarbell et al (1992), observes seven features of expressed distress under three major headings - vocal pain expression, facial pain expression and body pain expression. Each of the seven features is either present (score 1) or absent (score 0). As described, it requires observation over a 30-minute period. This was impracticable in the context in which the present study was carried out so, after a series of pilot investigations, the observation period was reduced to 11 minutes. This interval was chosen because no greater discrimination between groups could be determined after this period of time.

The pre-operative blood sample and the swabs and aspirations were converted to alkaline haematin and the blood loss calculated using the method previously described. ^2,7 This was then adjusted for the ‘root score’ (number of roots - arising from the tooth types extracted) to give a standardised value.⁸

All data were analysed in SPSS for Windows (v9.0.0). Total blood loss per root was approximately normally distributed and so independent t-tests were used to test for differences in total blood loss per root between experimental and control groups. To test for an operator effect on total blood loss per root, One Way Analysis Of Variance (ANOVA) models were used.

The skewed nature of the distress score for the control group meant that non-parametric statistics had to be used. The Mann-Whitney U test was used to test for differences in distress score between control and experimental groups.

Test group	Number of patients	Mean rank distress score
E (with local anaesthetic)	50	63.93
C (without local anaesthetic)	50	37.07

The figure shows the blood loss per root for each of the patients. Two outlier results are seen at 6.16 and 3.96. Once these were removed (see discussion) the findings were compared using the (unpaired) t-test (n experimental = 48; n control = 50). Mean (s.d.) total blood loss per root in the experimental group was 0.79 (0.06) whereas in the control group this was 1.19 (0.10). This yielded a mean (SE) difference of 0.4 (0.12) (t-value=3.27 on 98 df) with a p-value of 0.001.

To compensate for any possibility of skewed distribution in the data, the results were re-calculated using the Mann-Whitney (non-parametric) test. The results were still significant with p=0.006

The blood loss per root was calculated for each operator. No significant differences were found (total mean blood loss per root 0.9998ml; s.d. 0.63; p=0.470).

The mean rank scores for distress following operation are recorded in the Table. A Mann Whitney U Test revealed that the mean rank distress scores for the experimental (with local anaesthetic) group were significantly higher than those without local anaesthetic (p < 0.0001).

Of the methods used to assess blood loss following tooth extraction, that of Henderson et al (1997), has been shown to provide reliable, reproducible results. The method is straightforward, demanding little laboratory equipment and the shortest of procedures in theatre, adding little to the operating time.

It was the intention of the study to assess the haemostatic effect of the use of lignocaine with adrenaline for the extraction of primary teeth.

The blood loss is presented as blood loss per root.2 This allows for the different number of roots with each tooth type and recognises the effect of wound surface area on the potential for bleeding. Nevertheless, there are some limitations to the technique when used in small children. Most notable was the occasional need to delay venepuncture until after the induction of anaesthesia.

The age group of patients chosen (3-5 years) and the teeth assessed (primary teeth only) was designed to reduce the variability in root size, which would otherwise have arisen from either, as yet, incomplete root formation in a younger group or resorption in an older group.

The results for the blood loss were ostensibly normally distributed with the exception of two outlying points in the experimental group. Further investigation confirmed that these were healthy children with no underlying reason for haemorrhage, nor any note of any surgical difficulty. Chance dictates that there may always be such aberrant points within a sample and statistical advice supported the view that these points should be removed from the calculation. Henderson et al (1997), examining the blood loss following the removal of the primary teeth found this to range from 2.5 to 57 ml. The present study puts blood loss at 2.39 ml for a single two-rooted tooth. The use of lignocaine 2% and adrenaline 1:80,000 reduced this to 1.98 ml which was statistically significant (p=0.001). If this were to be extrapolated to Henderson et al (1997), results then their highest value of 57 ml would be reduced to 47.2 ml, a reduction of 27%.

The range of values for circulating blood volume for children aged 3-5 years has been calculated as lying between 0.892 and 1.505 litres.2 Thus, although the reduction of blood loss of 0.41 ml per root is statistically significant, by comparison with the total blood volume it is physiologically insignificant.

In the present study, only one observer was available to record the distress scores. This made for considerable logistical problems when one child rapidly followed another out of the operating theatre.

These were young children, aged 3-5 years. There was a clear and marked increase in the measures of distress postoperatively in those children who had received local analgesia. Holloway and Swallow (1975) noted the importance of explaining to the child sensations to be expected arising from local analgesia just before their occurrence, in order to allay fears.9 Andlaw and Rock (1996) recorded that local analgesia may present a special problem in the pre-school child because of their unfamiliarity with the sensations and their inability to adjust to them. Although explanation had been made to the children regarding the likely sensations that would occur post-operatively, such advice might well have been forgotten in the period of recovery from anaesthesia. It is frequently observed that conscious children dislike the sensation of local analgesia more than the process itself. A child who is compliant throughout a first visit including local analgesia often proves to be a reluctant patient on subsequent visits.

In summary, whilst the use of local analgesia with vasoconstrictor made a notable reduction in blood loss in this group, there was an associated, significant increase in postoperative distress. This article has demonstrated the surgical usefulness of infiltration local analgesia with epinephrine as a haemostat for dental extractions under general analgesia.

However, its association with increased distress in the recovery period challenges its overall value and there would seem little benefit in continuing with the practice.

We are very grateful to the Nursing, Anaesthetic and Surgical staff of the Bristol Dental Hospital day case theatre for their help and co-operation in this study. We extend our thanks to the patients and parents for their agreement to take part in this study. This study was supported by the Clinical Trials Group, Oral and Dental Science, University of Bristol.

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Copyright date: 3rd May 2001
Correspondence: P.J.M. Crawford, Paediatric Dentistry, Division of Child Dental Health, Department of Oral and Dental Science, University of Bristol, Bristol BS1 2LY, UK

Career advice - the role of appraisal. J.R.Coll.Surg.Edinb. 2001; 46 (4): 213-15

The author’s address should read Member of the Training Advisers’ Group, Stirling Royal Infirmary, Livilands, Stirling UK. Correspondence should be addressed to I Ritchie, Training Advisers’ Group, Royal College of Surgeons of Edinburgh, Nicolson Street, Edinburgh EH8 9DW, UK.