a clinical audit into the success rate of inferior alveolar nerve block analgesia in general dental...

7/29/2019 A Clinical Audit Into the Success Rate of Inferior Alveolar Nerve Block Analgesia in General Dental Practice

1/4

Introduction

The purpose of this study was to produce some

observational evidence of the success rate of inferior

alveolar nerve block (IDB) analgesia that is achieved

in general dental practice.

A recent article in the British Dental Journal1

referred to IDB analgesia and described how failures

could be minimised. Heasman and Beynon2 also

described failure of IDB analgesia citing the following

as some of the reasons for failure:

Intravascular injection.

Unusual local anatomy.

Idiosyncratic local analgesic resistant patients.

Accessory innervation to the teeth.

A study by Simon et al3 concluded that administration

of anaesthetic injections is a rarely discussed but sig-

nificant contributor to the overall professional stress for

many dentists. However the quoted success rates for

dental local analgesic administrations are enormously

variable with the range beginning as low as 80%.4-6

Until more evidence of the expected norms of failure

are quantified it will be difficult for dentists to assess

their own standards of technique in this important area

of pain control.

There are a number of potential neurological com-

plications of local anaesthetics used in dentistry.

These include facial nerve palsy, transient amaurosis,

transient paraesthesia and, rarely, transient unilateral

deafness.7 The continuous review of technique by

practitioners will help to minimise the risks involved.

With the advent of clinical governance in the UK it is

now essential that practitioners audit some of theirclinical procedures. Publication of results is clearly

needed to give some idea of the standards to be

expected.

LOCAL ANALGESIA AND PRIMARY DENTAL CARE

A Clinical Audit into the Success Rate ofInferior Alveolar Nerve Block Analgesia

in General Dental PracticeAndrew Keetley and David R Moles

KEY WORDS: CLINICAL AUDIT, INFERIORALVEOLAR NERVE BLOCKANALGESIA, FACIAL NERVE PALSY, GENERAL DENTAL PRACTICE PRIMARY DENTALCARE 2001;8(4):139-142

Aims and objectives:The aim of this

study was to produce some observa-

tional evidence of the success rate of

inferior alveolar nerve block (IDB)

analgesia that is achieved in general

dental practice. The objective was

to help provide some measure ofexpected failure rates and help dental

practitioners in their self-appraisal of

this crucial basic skill.

Method: Up to 100 consecutive IDB

analgesia procedures for four dentists

were recorded. In a subdivision of this

study 200 consecutive IDBs for a fifth

dentist were recorded.This dentist had

the greatest experience of giving IDB

analgesia of the dentists in this study.

In this part of the study the dentist

made a note if he anticipated that the

procedure would fail. The reason for

this was that it was felt that ex-

perienced dental practitioners could

predict when failure was about to

occur. The level of facial nerve palsy

was also recorded.

Results: Overall, 533 of 580 (91.9%)local anaesthetic administrations were

deemed to be successful. The only

factor that significantly affected the

likelihood of success was the practi-

tioner administering the local anaes-

thetic, and this was only borderline

statistically significant. In order to be

certain that the other factors did not

affect the outcome, the data were

re-analysed using the technique of

Poisson regression. This technique in-

vestigated the effects of each of the

factors in turn while controlling for

the differences in success that can be

attributed to the different practition-

ers. The regression analyses also did

not detect any differences in success

that could be attributed to any of the

other recorded factors. The incidenceof facial palsy was 0.3%.

Conclusion: This paper gives an

insight into the possible success rates

to be encountered by general dental

practitioners when they administer

IDB analgesia. The only recorded fac-

tor that could be shown to affect the

chance of a successful local analgesic

was the operator. The incidence of

facial nerve palsy at 0.3% may be

more common than has previously

been considered.

PRIMARY DENTAL CARE OCTOBER 2001 139

DA Keetley BDS, DGDP(UK), DPDS.

General Dental Practitioner, KirkhallamDental Practice,

Ilkeston, Derbyshire.

DR Moles MSc, BDS, DDPH.

Clinical Lecturer and MRC Special Fellow in Health Services

Research, Oral Pathology Unit, Eastman Dental Institute for

Oral Health Care Science,London.


2/4

Aims and ObjectivesThe aim of this study is to help provide some measure of

expected failure rates and help dental practitioners in

their self-appraisal of this crucial basic skill. It has to beemphasised that if a skill cannot be measured it cannot

be managed. However, armed with some information

regarding expected failure rates, general dental practi-

tioners will be more able to audit their own results.

MethodologyOne hundred consecutive IDB analgesia procedures for

four dentists were recorded. In a subdivision of this

study 200 consecutive IDBs for a fifth dentist were

recorded. This dentist had the greatest experience of giv-

ing IDB analgesia of the dentists in this study. In this partof the study the dentist made a note if he anticipated that

the procedure would fail. The reason for this was that it

was felt that experienced dental practitioners could pre-

dict when failure was about to occur. The incidence of

any facial nerve palsy was recorded.

Anaesthetic technique

A 27 gauge long needle was used. The anaesthetic in all

cases was lignocaine 2%/adrenaline 1:80,000. Self-aspi-

rating syringes were used in all cases. Although there is

evidence to suggest that accidental intra-arterial injection

can be avoided with traditional local anaesthetic car-tridges8 the practice involved in the study had used the

Astra self-aspirating system for many years. The classic

IDB technique was used. This involves injecting into the

pterygomandibular space while the barrel of the syringe

is parallel with the occlusal surfaces of the mandibular

teeth. Figure 1 describes the anatomy of the region. The

aim is detect bone with tactile skill close to the lingula.

No attempt was made to influence dentists as to whether

they used the indirect or direct method of IDB. The alter-

native IDB techniques described by Gow-Gates9 and

Akinosi10

were not employed in this study. It is felt thatthese techniques are not commonly used by general

practitioners.

The criteria for recording a successful IDB procedure

was that the labial attached mucosa between the lower

second incisor and the lower canine tooth, on the

affected side, should be sufficiently anaesthetised to

allow firm probing with a sharp explorer. Only one car-

tridge of anaesthetic was allowed and no buccal infiltra-

tion analgesia used until the test for success had been

made. A further category for failure was that when,

despite this first test showing success, the patient

showed signs of discomfort during dental procedure.The data collected for each local anaesthetic adminis-

tration are listed in Table 1. These data were analysed

using chi-squared and Poisson regression techniques to

determine whether any of the recorded factors influ-

enced the likelihood of obtaining successful analgesia.

ResultsFor up to 100 consecutive IDB analgesia procedures (200

for one dentist) the following information was recorded

for each patient: date of birth, sex, quadrant anaes-

thetised, dental procedure performed. The number ofpatients (458) is fewer that the number of IDBs (580)

because some patients returned on several visits during

their treatment.

The results are displayed in Tables 2, 3 and 4. Five

hundred and eighty inferior alveolar nerve blocks were

administered by the five participating practitioners dur-

ing the course of the audit. The recipient patients varied

in age from 6 to 93 years old, with a mean age of 38.4

years (standard deviation 16.8 years). There were slightly

more female (298, 51.4%) than male patients in the sam-

ple. Half (292, 50.3%) of the patients received the local

anaesthetic as part of conservation treatment. The nextmost common procedure requiring inferior alveolar

nerve block was extraction (138, 23.6%).

Overall, 533 (91.9%) of local anaesthetic administra-

SUCCESS RATE OF IDBS

140 PRIMARY DENTAL CARE OCTOBER 2001

Factor Possible values for factor

Practitioner administering 1-5

the anaesthetic

Sex of patient Male/female

Age of patient 6-93 years

Quadrant Lower left/lower right

Reason for local anaesthetic Conservation, periodontal

(procedure) therapy, endodontics, extraction

Outcome of anaesthetic Success/f ailure

Table 1: Information collected for each local

anaesthetic administration

A

B

E

F

C

D

Figure 1 Diagrammatic description of the inferior alveolar nerve block.

A: Mandibular ramus. B: Masseter. C: Medial pterygoid. D: Buccal fat

pad. E: Superior constrictor of the pharynx F: Buccinator.


3/4

tions were deemed to be successful. The success rates

for each of the potential explanatory factors are shown

inTable 3. The only factor that significantly affected the

likelihood of success was the practitioner administering

the local anaesthetic, and this was only borderline statis-

tically significant at the 5% level (chi-squared 4 df=9.56,

p=0.048). In order to be certain that the other factors did

not affect the outcome, the data were re-analysed using

the technique of Poisson regression. This technique

investigated the effects of each of the factors in turn

while controlling for the differences in success that can

be attributed to the different practitioners. The regression

analyses (results not shown) also did not detect any dif-

ferences in success that could be attributed to any of the

other recorded factors.

The percentage failure rates for each dentist are

shown inTable 4 with additional note of the number ofyears since qualification.

Dentist 5 felt that he could identify when failure was

about to occur immediately following the procedure. The

results show that in eight out of 10 failures the prediction

was accurate, unexpected failure occurring only in two

out of a total 179 consecutive IDBs. In only one case did

the dentist predict a failure and the IDB actually achieve

success. This raises the question that if failure is pre-

dictable should dental procedures be postponed at

that point and alternative methods of pain control be

considered?

An incidental finding in the study was that facialnerve palsy occurred in two patients. The dentist was

different in these two cases. This gives the complication

an incidence of 0.3% in this series. This is possibly higher

than some may have expected. Interestingly dentist 5

had wrongly predicted IDB failure in the case that

developed facial nerve palsy. It appears that the proce-

dure was identified as differing from the usual on that

patient at that time.

DiscussionIn this audit of inferior alveolar nerve blocks, the only

recorded factor that could be shown to affect the chance

of a successful local analgesic was the operator. This

reinforces the notion that successful analgesia is tech-

nique-sensitive. The implications of this are that training

should continue through a dentists vocational training

year and beyond. A regular audit of success rates would

help practitioners to determine whether their technique

was improving as they would expect or not.

The greater success rate of IDB by the most ex-

perienced dentist was not unex-

pected. However, it is accepted thatthis is a small study. There is also the

possibility that the greater success of

more experienced dentists is pro-

vided by other confounding vari-

ables. It is said that dentists get to

know their patients and this helps

in, for example, providing successful

IDB analgesia for their patients. This

may be true. An established practi-

tioner may have a large group of

patients who place increased trust in

their dentist, having built a relation-ship over a number of years. There

is potential at least for some degree

of placebo effect on success. How-

ever it is unlikely that this would extend to the patient

continuing with surgery or extractions if analgesia was

not successful.

Perhaps patients get to know their dentist, the point

being that if a dentist provides unsuccessful analgesia on

several occasions the patient is likely to seek treatment

elsewhere. This may lead to a certain amount of self-selec-

tion with more established practitioners treating a group

of patients on whom IDB is successful. If this were truethen there would also be a group of patients who sought

treatment with a new dentist. The least experienced

Number of % Failure

years since rate of IDB

qualification an analgesia

Dentist 1 Less than 1 10.1%

Dentist 2 Less than 1 9.0%

Dentist 3 4.5 years 11.2%

Dentist 4 14.5 years (8.5 years PT) 3.7%

Dentist 5 14.5 years 5.6%

Total 580 IDB procedures 8.1%

Factor Value of factor Administrations Successes (%) P-value

Practitioner 1 179 169 (94.4) 0.048

2 109 105 (96.3)

3 97 84 (86.6)

4 88 80 (90.9)

5 107 95 (88.8)

Sex of patient Male 282 258 (91.5) 0.727

Female 298 275 (92.3)

Quadrant Left 297 277 (93.3) 0.216

Right 283 256 (90.5)

Procedure Conservation 292 268 (91.8) 0.238

Periodontal 66 63 (95.5)Endodontics 85 74 (87.1)

Extraction 137 128 (93.4)

Procedure Frequency (%)

Conservative/restorative procedures 292 (50.3)

Endodontic procedures 85 (14.7)

Periodontal procedures 66 (11.4)

Extractions 137 (23.6)

Total 580 (100.0)

DA KEETLEY, DR MOLES

PRIMARY DENTAL CARE OCTOBER 2001 141

Table 2: Distribution of dental procedure type for

the total sample

Table 4: Percentage failure rates for each dentist

Table 3: Success rates for inferior alveolar nerve blocks by potential

explanatory factors


4/4

dentists in this study were new to the practice and were

treating a higher proportion of patients who were new to

the practice. There is the possibility that some of these

patients were from a different self-selected group,

namely who had found IDB unsuccessful in the past.

Meecham1 put forward the case for using a blunder-

buss approach for patients who had experienced failed

anaesthesia in the past. The rationale is that it is moredifficult to gain patients trust if they have been hurt in

the past. The blunderbuss approach is to use IDB and

buccal infiltration from the onset with the possible addi-

tion of a second IDB higher up the mandibular ramus.

Dentists in this study achieved successful IDB analge-

sia at the second attempt after failure had occurred. This

may be because it is easier to move the needle painlessly

in tissue and palpate the bony landmarks. Also a higher

needle position was employed on all repeat injections.

Factors identified by dentist 5 that helped predict an

unsuccessful IDB were:

Unable to locate anatomical landmarksespeciallythe pterygomandibular raphe.

Unable to find a bony landmark with the needle.

Unable to direct the needle satisfactorily due to tough

tissue in the pterygomandibular space.

Awkward tongue. Either excessively large or due to

lifting posteriorly. Some patients seem unable to allow

the tongue to rest passively.

Difficult anatomy where posterior teeth have been lost

and alveolar resorption has been excessive.

Needle curved when withdrawn. This is usually a sign

that the dentist has struggled to manipulate the needle

within the tissues.It is interesting that some practitioners seem reticent to

provide IDB analgesia using other techniques whenever

they can. Although dentists cite infiltration analgesia as

more comfortable than IDB analgesia, there is evidence

to show that patients do not perceive any difference.11

Conclusion

Inferior alveolar nerve block analgesia (IDB) is an

important feature of general dental practice. This paper

gives an insight into the possible success rates to be

encountered by general dental practitioners when they

administer IDB analgesia. The only recorded factor that

could be shown to affect the chance of a successful localanalgesic was the operator. The incidence of facial nerve

palsy may be more common than has previously been

considered.

References1. Meechan JG. How to overcome failed local anaesthesia. Br Dent J 1999;186:15-20.

2. Heasman PA, Beynon ADG. Clinical anatomy of regional analgesia: an approach

to failure. Dent Update 1986;Nov/Dec:469-76.

3. Simon JF, Peltier B, Chambers D, Downer J. Dentists troubled by the administra-

tion of anaestheic injections: Long term stresses and effects. Quintessence Int

1994;25:641-6.

4. Evers H, editor. Handbook of Dental Local Anaesthesia. Copenhagen: Schultz

Medical Information, 1981.

5. Rood J.P. Some anatomical and physiological causes of failure to achievemandibular anaesthesia. Br J Oral Surg 1977:15:75-82.

6. Cowan A. Minimum dosage technique in the clinical comparison of representa-

tive modern local anaesthetic agents. J Dent Res 1964:43:1228-9.

7. Crean S, Powis A. Neurological complications of local anaesthetics in dentistry.

Dent Update 1999;Oct:344-9.

8. Meechan JG, Czachur KJ, Blair GS, McCabe JF. The ability of traditional and

self aspirating dental local anaesthetic cartridges to aspirate blood under

simulated arterial conditions Br Dent J 1986;160:239-41.

9. Gow-Gates GAE. Mandibular conduction anesthesia: a new technique using

extra-oral landmarks. Oral Surg 1973;36:321-8.

10. Akinosi JO. A new approach to the mandibular nerve block. Br J Oral Surg

1977;15:83-7.

11. Matthews R, Ball R, Goodley A, Lenton J, Riley C, Sanderson S, et al. The

efficacy of local anaesthetics administered by general dental practitioners.

Br Dent J 1997;182:175-8.

Acknowledgement: Miss G Taylor for help with illustration.

SUCCESS RATE OF IDBS

142 PRIMARY DENTAL CARE OCTOBER 2001

Correspondence: DA Keetley,

The Manor House, Bramcote, Nottingham NG9 3DR.

E-mail: [email protected]

a clinical audit into the success rate of inferior alveolar nerve block analgesia in general dental...

Documents