- Email: [email protected]
The use of patient-controlled transcutaneous electronic nerve stimulation (TENS) to decrease the discomfort of regional anaesthesia in dentistry: a randomised controlled clinical trial
Journal of Dentistry Journalof Dentistry
26 (1998)
417-420
The use of patient-controlled transc-utaneous electronic nerve stimulation (TENS) to decrease the discomfort of regional anaesthesia in dentistry: a randomised controlled clinical trial J.G. Meechana3*, A.J. Gowans”, R.R. Welburyb “Department of Oral and Maxillofacial Surgery, The Dental School and Hospital, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK bDepartment of Child Dental Health, The Dental School and Hospital, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK
Received2 July 1997;accepted4 November 1997
Abstract Objective: To compare the use of topical anaesthesia and transcutaneous electronic nerve stimulation (TENS) as means of reducing the discomfort of inferior dental block injections. Methods: One hundred adult dental patients received 2% lignocaine with 1:80000 adrenaline for long buccal and inferior dental block anaesthesia.The long buccal injections were given first with no prior mucosal preparation. Patients received inferior dental blocks after one of the following mucosal preparations: (1) no pretreatment; (2) a 2 min application of 20% benzocaine topical anaesthetic; (3) application of patient-controlled TENS at the injection site. Patients scored injection discomfort after each administration on a 100 mm visual analoguescale. Results: The discomfort of the long buccal injection did not differ between the three groups of patients (F2,g7= 1.O). There were significant differences in the pain scores for the inferior dental block injections (F 2,97= 5.3; p < 0.01). Injection discomfort following TENS was less than that following no pretreatment (p < 0.01) and after topical anaesthetic application (p < 0.05). The use of topical anaesthesia did not produce a significant change in injection discomfort compared with no pretreatment. Conclusion: The use of TENS reduces injection discomfort during inferior dental block anaesthesia.0 1998 Elsevier Science Ltd. All rights reserved. Keywords:
TENS; Local; Anaesthesia; Dental; Topical; Intra-oral
1. Introduction The administration of pain-free local anaesthesia is the aim of all caring practitioners. A number of techniques are available which are reputed to decrease the discomfort of local anaesthetic injections. These include the application of topical anaesthetics [l] and the use of transcutaneous electronic nerve stimulation (TENS) [2]. Topical anaesthetics for intra-oral use have a limited ability to penetrate deep into the submucosal tissues and are therefore of most value when needle penetration is only a few millimetres. In theory TENS should mask even deep tissue penetration. It was the purpose of the present investigation to compare an intra-oral topical anaesthetic and patient-controlled TENS as means of reducing the discomfort of intra-oral injections involving deep tissue penetration. The injection * Correspondingauthor.Tel.: [email protected]
0191 2228292;
fax: 0191 2226137;
e-mail:
O300-5712/98/$19.00Q 1998Elsevier Science Ltd. All rights reserved PII
SO300-5712(97)00062-6
studied was the inferior dental block (with lingual block) which involves penetration of the needle to a depth of approximately 25 mm.
2. Materials
and methods
Ethical approval was obtained and 100 adult patients requiring the extraction of a lower tooth which necessitated the administration of long buccal and inferior dental (including lingual) block anaesthesia gave informed written consent and participated in the study. Patients with convulsive disorders, cardiac pacemakers, conditions affecting the central nervous system and pregnant women were excluded. Patients were randomly assigned to one of three groups (see below). The local anaesthetic solution used was 2% lignocaine with 1:80 000 adrenaline in every case. All injections were administered by the same operator. The initial injection for each patient was the long buccal block which was administered without mucosal preparation. A
418
J.G. Meechan
et al./Journal
of Dentistry
26 (1998)
417-420
Table 1 Pooled VAS scores for each treatment IDB pretreatment
Number
LB pain score (mm) mean ? SD
IDB pain score (mm) mean I SD
None Benzocaine TENS
34 32 34
27.3 2 19.5 31.4 I 25.1 34.8 2 21.3
39.8 I! 27.7 32.8 i 20.8 22.2 t- 17.4
LB = long buccal block injection, IDB = inferior dental and lingual
Fig. 1. The injection-assist TENS machine. The leads are shown at the bottom of the picture and the patient control dial is on the lower lefthand comer of the machine.
35 mm 27 gauge needle was used. Following this injection the patient was asked to “score” the injection discomfort on a 100 mm visual analog (VAS) scale with end points “no pain’ ’ and ‘ ‘unbearable pain’ ’ . The second injection was the inferior dental and lingual block. This was administered using the direct technique [3] with a 27 gauge 35 mm needle. Prior to the second injection one of the following pretreatments (which determined group allocation) was performed: 1. no mucosal preparation but a delay of two minutes following completion of the long buccal injection pain score; 2. application of 20% benzocaine topical anaesthetic (Septodont, Saint-Maur, France) for 2 min at the needle penetration point; 3. application of the leads of an injection-assist TENS machine (3M, St Paul, Minnesota, USA) (Fig. 1) on the thumb of the operator’s glove with positioning of the leads either side of the needle puncture point
on the operators
glove
at the
block injection.
(Fig. 2). This thumb position is that which is normally used during the injection. The injection-assist machine had the rate and width of the signal pulse preset by the operator. The patient adjusted the amplitude of the TENS signal until a comfortable warm vibration was felt. The needle was inserted between the electrodes and the level of stimulation was maintained throughout the injection. The TENS stimulation was slowly switched off once the needle was removed. The discomfort produced by the second injection was assessed by the patient using the VAS immediately at the end of administration. The results were analysed using ANOVA, Student’s t-test and Chi square.
3. Results The results are shown in Tables 1 and 2. Thirty-four patients had no mucosal treatment prior to the inferior dental block, 32 were treated with benzocaine and 34 received TENS. The discomfort produced by the long buccal injection did not differ between the three groups of patients (F2,g7 = 1.O); however, there were significant differences in the pain experienced during the inferior dental and lingual block administrations (F2,97 = 5.3; p < 0.01). TENS pretreatment produced less discomfort than no pretreatment (t = 3.14; p < 0.01) and when compared with topical anaesthetic application (t = 2.24; p < 0.05). The use of the topical anaesthetic did not affect the pain experience during the Table 2 Comparison
Fig 2. The electrode of the TENS machine injection site for an inferior dental block.
group for each injection
of injection
discomfort
between
injections
IDB pretreatment
No. reporting IDB more painful”
No. reporting LB more painful”
None Benzocaine TENS
23 18 10
10 12 24
a 3 patientsreported no difference in discomfort between LB = long buccal block injection. IDB = inferior dental and lingual block injection.
injections.
J.G. Meechan
et al./Journal
inferior dental block injection when compared with no pretreatment (t = 1.17). Ninety-seven of the 100 patients found one injection more uncomfortable than the other. Those patients who received no pretreatment or topical application were more likely to “score” the inferior dental block injection more uncomfortable than the long buccal block compared with the converse for patients who received TENS (x2 = 11.6; p < 0.01) (Table 2).
4. Discussion This investigation attempted to study the effects of different pretreatments on the discomfort of intra-oral regional block anaesthesia on a patient population. The design of the study was such that it incorporated a component which assessed each treatment group’s pain perception of an intra-oral injection. This component was the administration of the long buccal block injection without mucosal pretreatment. This in a sense allowed a “base-line” comparison across treatments. The fact that the three groups of patients did not differ in their pooled pain recordings for the long buccal injection suggests they had the same “global” pain tolerance and offers a measure of confidence that any difference in the pain experienced during the inferior dental block injections was due to the mucosal pretreatment. Such a difference was noted in this study. TENS reduced injection discomfort compared with no pretreatment and when compared with a 2 min application of 20% benzocaine. Conventional intra-oral topical anaesthetics have a limited ability to penetrate deep into tissue. Although they may mask the discomfort of surface penetration, it would be surprising if they were effective at the depths of penetration required for deep regional block injections such as the inferior dental block administration where the needle is inserted to a depth of around 25 mm. Their use for such injections can be questioned. Nevertheless, some practitioners apply topical anaesthetics before regional block injections. The inclusion of a topical application was considered essential in this investigation to provide a second “active’ ’ treatment for comparison to TENS. There are various topical anaesthetic preparations available for intraoral use and they are equally effective at anaesthetising nonkeratinised oral mucosa [l]. In the present study 20% benzocaine was used as it has a pleasant flavouring.The results show that a 2 min application of topical anaesthetic to the site of needle penetration did not affect the pain experienced during inferior dental block administration when compared with no mucosal preparation. TENS has been used in dentistry for a number of years to treat both chronic and acute pain conditions [2]. Leads may be placed extra- or intra-orally, When used to treat chronic conditions such as temporomandibular joint pain [4,5], TENS probably achieves success by two mechanisms. Firstly, TENS flushes out the products of tissue destruction
of Dentistry
26 (1998)
417-420
419
by the dual mechanisms of an increase in tissue perfUSiOn and stimulation of musclecontraction. Secondly, prolonged use of TENS promotesthe releaseof endogenouspain control mediators such as endorphins [6]. When used to treat acute pain during dental operative treatment [5,7] or as a means of reducing injection discomfort, TENS activates large diameter nerve fibres which have a lower threshold of response to electrical activity than smaller diameter fibres. This closes the central gating mechanismto small diameter nerve (that is pain) transmission [8]. The depth of needle penetration should not influence the efficacy of TENS if the method of action is closing the gate to peripheral pain perception by stimulation of larger diameter nerve fibres. Despite the theoretical basisfor the efficacy of TENS, its value in reducing the discomfort of intra-oral injections is debatable. An investigation of 101 injections (infiltrations and regional blocks) given by seven operators in association with the injection-assist system reported a reduction in injection discomfort in 74% of cases [9]. Another study [lo], using a different TENS machine, showed that when needle penetration was superficial, TENS was not as effective as sometopical anaestheticsin reducing injection discomfort. The TENS device usedin the present study was more effective than topical anaesthesia during regional block injections. These conflicting results could be due to the use of different TENS machines.Alternatively, the use of different surface preparationsto reduce discomfort during different types of injection may be warranted (for example topical application prior to infiltration anaesthesiaand TENS before deeperregional blocks). Although injection discomfort was significantly reduced by the use of TENS in the present study it was not completely eliminated. Although TENS is a potentially useful part of the dentist’s pain-control armamentarium,it is not suitable for use in all patient groups. It should be avoided in patients with demand-type pace-makers, in those with convulsive conditions and in individuals with any neurological disorder of the head and neck (such as trigeminal neuralgia). The safety of TENS in pregnancy has not been established. In conclusion, patient-controlled TENS reduced but did not eliminate the discomfort experienced during inferior dental and lingual block injections when compared with the use of 20% benzocaine topical anaesthetic.The use of the topical anaesthetic prior to inferior dental block anaesthesiadid not affect discomfort when compared with no mucosalpreparation.
References 111Rosivack
RG, Koenigsberg SR, Maxwell KC An analysis of the effectiveness of two topical anaesthetics. Anesth. Prog., 1990;37:290-292. [21 Quarnstrom F Electronic dental anesthesia. Anesth. Prog.,
1992;39:162-177. [31 Roberts DH, Sowray JH, Local analgesia in dentistry, Wright,
1987: 116-17.
3rd ed. Bristol:
420
J.G. Meechan
et alJJourm1
[4] Geissler PR, McPhee PM Electrostimulation in the treatment of pain in the mandibular dysfunction syndrome. J. Dent., 1986;14: 62-64. [5] Clark MS, Silverstone LM, Lindenmuth J et al. An evaluation of the clinical analgesia/anesthesia efficacy on acute pain using the high frequency neural modulator in various dental settings. Oral Surg., 1987;63:501-505. [6] Malamed SF, Handbook of local anesthesia, 4th ed. St Louis: Mosby, 1997: 292-3. [7] Donaldson D, Quarnstrom F, Jastak JT The combined effect of nitrous
of Dentistry
26 (1998)
417-420
oxide and electrical stimulation during restorative dental treatment. J. Am. Dent. Assoc., 1989;118:733-736. [S] Melzack R, Wall P Pain mechanisms a new theory. Science, 1965;150:971-979. [9] Burke FJT Dentist and patient evaluation of an electronic dental analgesia system for controlling discomfort of injections. Dent. Update, 1997;24:154-157. [lo] Meechan JG, Winter RA A comparison of topical anaesthesia and electronic nerve stimulation for reducing the pain of intra-oral injections. Br. Dent. J., 1996;181:333-335.
26 (1998)
417-420
The use of patient-controlled transc-utaneous electronic nerve stimulation (TENS) to decrease the discomfort of regional anaesthesia in dentistry: a randomised controlled clinical trial J.G. Meechana3*, A.J. Gowans”, R.R. Welburyb “Department of Oral and Maxillofacial Surgery, The Dental School and Hospital, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK bDepartment of Child Dental Health, The Dental School and Hospital, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK
Received2 July 1997;accepted4 November 1997
Abstract Objective: To compare the use of topical anaesthesia and transcutaneous electronic nerve stimulation (TENS) as means of reducing the discomfort of inferior dental block injections. Methods: One hundred adult dental patients received 2% lignocaine with 1:80000 adrenaline for long buccal and inferior dental block anaesthesia.The long buccal injections were given first with no prior mucosal preparation. Patients received inferior dental blocks after one of the following mucosal preparations: (1) no pretreatment; (2) a 2 min application of 20% benzocaine topical anaesthetic; (3) application of patient-controlled TENS at the injection site. Patients scored injection discomfort after each administration on a 100 mm visual analoguescale. Results: The discomfort of the long buccal injection did not differ between the three groups of patients (F2,g7= 1.O). There were significant differences in the pain scores for the inferior dental block injections (F 2,97= 5.3; p < 0.01). Injection discomfort following TENS was less than that following no pretreatment (p < 0.01) and after topical anaesthetic application (p < 0.05). The use of topical anaesthesia did not produce a significant change in injection discomfort compared with no pretreatment. Conclusion: The use of TENS reduces injection discomfort during inferior dental block anaesthesia.0 1998 Elsevier Science Ltd. All rights reserved. Keywords:
TENS; Local; Anaesthesia; Dental; Topical; Intra-oral
1. Introduction The administration of pain-free local anaesthesia is the aim of all caring practitioners. A number of techniques are available which are reputed to decrease the discomfort of local anaesthetic injections. These include the application of topical anaesthetics [l] and the use of transcutaneous electronic nerve stimulation (TENS) [2]. Topical anaesthetics for intra-oral use have a limited ability to penetrate deep into the submucosal tissues and are therefore of most value when needle penetration is only a few millimetres. In theory TENS should mask even deep tissue penetration. It was the purpose of the present investigation to compare an intra-oral topical anaesthetic and patient-controlled TENS as means of reducing the discomfort of intra-oral injections involving deep tissue penetration. The injection * Correspondingauthor.Tel.: [email protected]
0191 2228292;
fax: 0191 2226137;
e-mail:
O300-5712/98/$19.00Q 1998Elsevier Science Ltd. All rights reserved PII
SO300-5712(97)00062-6
studied was the inferior dental block (with lingual block) which involves penetration of the needle to a depth of approximately 25 mm.
2. Materials
and methods
Ethical approval was obtained and 100 adult patients requiring the extraction of a lower tooth which necessitated the administration of long buccal and inferior dental (including lingual) block anaesthesia gave informed written consent and participated in the study. Patients with convulsive disorders, cardiac pacemakers, conditions affecting the central nervous system and pregnant women were excluded. Patients were randomly assigned to one of three groups (see below). The local anaesthetic solution used was 2% lignocaine with 1:80 000 adrenaline in every case. All injections were administered by the same operator. The initial injection for each patient was the long buccal block which was administered without mucosal preparation. A
418
J.G. Meechan
et al./Journal
of Dentistry
26 (1998)
417-420
Table 1 Pooled VAS scores for each treatment IDB pretreatment
Number
LB pain score (mm) mean ? SD
IDB pain score (mm) mean I SD
None Benzocaine TENS
34 32 34
27.3 2 19.5 31.4 I 25.1 34.8 2 21.3
39.8 I! 27.7 32.8 i 20.8 22.2 t- 17.4
LB = long buccal block injection, IDB = inferior dental and lingual
Fig. 1. The injection-assist TENS machine. The leads are shown at the bottom of the picture and the patient control dial is on the lower lefthand comer of the machine.
35 mm 27 gauge needle was used. Following this injection the patient was asked to “score” the injection discomfort on a 100 mm visual analog (VAS) scale with end points “no pain’ ’ and ‘ ‘unbearable pain’ ’ . The second injection was the inferior dental and lingual block. This was administered using the direct technique [3] with a 27 gauge 35 mm needle. Prior to the second injection one of the following pretreatments (which determined group allocation) was performed: 1. no mucosal preparation but a delay of two minutes following completion of the long buccal injection pain score; 2. application of 20% benzocaine topical anaesthetic (Septodont, Saint-Maur, France) for 2 min at the needle penetration point; 3. application of the leads of an injection-assist TENS machine (3M, St Paul, Minnesota, USA) (Fig. 1) on the thumb of the operator’s glove with positioning of the leads either side of the needle puncture point
on the operators
glove
at the
block injection.
(Fig. 2). This thumb position is that which is normally used during the injection. The injection-assist machine had the rate and width of the signal pulse preset by the operator. The patient adjusted the amplitude of the TENS signal until a comfortable warm vibration was felt. The needle was inserted between the electrodes and the level of stimulation was maintained throughout the injection. The TENS stimulation was slowly switched off once the needle was removed. The discomfort produced by the second injection was assessed by the patient using the VAS immediately at the end of administration. The results were analysed using ANOVA, Student’s t-test and Chi square.
3. Results The results are shown in Tables 1 and 2. Thirty-four patients had no mucosal treatment prior to the inferior dental block, 32 were treated with benzocaine and 34 received TENS. The discomfort produced by the long buccal injection did not differ between the three groups of patients (F2,g7 = 1.O); however, there were significant differences in the pain experienced during the inferior dental and lingual block administrations (F2,97 = 5.3; p < 0.01). TENS pretreatment produced less discomfort than no pretreatment (t = 3.14; p < 0.01) and when compared with topical anaesthetic application (t = 2.24; p < 0.05). The use of the topical anaesthetic did not affect the pain experience during the Table 2 Comparison
Fig 2. The electrode of the TENS machine injection site for an inferior dental block.
group for each injection
of injection
discomfort
between
injections
IDB pretreatment
No. reporting IDB more painful”
No. reporting LB more painful”
None Benzocaine TENS
23 18 10
10 12 24
a 3 patientsreported no difference in discomfort between LB = long buccal block injection. IDB = inferior dental and lingual block injection.
injections.
J.G. Meechan
et al./Journal
inferior dental block injection when compared with no pretreatment (t = 1.17). Ninety-seven of the 100 patients found one injection more uncomfortable than the other. Those patients who received no pretreatment or topical application were more likely to “score” the inferior dental block injection more uncomfortable than the long buccal block compared with the converse for patients who received TENS (x2 = 11.6; p < 0.01) (Table 2).
4. Discussion This investigation attempted to study the effects of different pretreatments on the discomfort of intra-oral regional block anaesthesia on a patient population. The design of the study was such that it incorporated a component which assessed each treatment group’s pain perception of an intra-oral injection. This component was the administration of the long buccal block injection without mucosal pretreatment. This in a sense allowed a “base-line” comparison across treatments. The fact that the three groups of patients did not differ in their pooled pain recordings for the long buccal injection suggests they had the same “global” pain tolerance and offers a measure of confidence that any difference in the pain experienced during the inferior dental block injections was due to the mucosal pretreatment. Such a difference was noted in this study. TENS reduced injection discomfort compared with no pretreatment and when compared with a 2 min application of 20% benzocaine. Conventional intra-oral topical anaesthetics have a limited ability to penetrate deep into tissue. Although they may mask the discomfort of surface penetration, it would be surprising if they were effective at the depths of penetration required for deep regional block injections such as the inferior dental block administration where the needle is inserted to a depth of around 25 mm. Their use for such injections can be questioned. Nevertheless, some practitioners apply topical anaesthetics before regional block injections. The inclusion of a topical application was considered essential in this investigation to provide a second “active’ ’ treatment for comparison to TENS. There are various topical anaesthetic preparations available for intraoral use and they are equally effective at anaesthetising nonkeratinised oral mucosa [l]. In the present study 20% benzocaine was used as it has a pleasant flavouring.The results show that a 2 min application of topical anaesthetic to the site of needle penetration did not affect the pain experienced during inferior dental block administration when compared with no mucosal preparation. TENS has been used in dentistry for a number of years to treat both chronic and acute pain conditions [2]. Leads may be placed extra- or intra-orally, When used to treat chronic conditions such as temporomandibular joint pain [4,5], TENS probably achieves success by two mechanisms. Firstly, TENS flushes out the products of tissue destruction
of Dentistry
26 (1998)
417-420
419
by the dual mechanisms of an increase in tissue perfUSiOn and stimulation of musclecontraction. Secondly, prolonged use of TENS promotesthe releaseof endogenouspain control mediators such as endorphins [6]. When used to treat acute pain during dental operative treatment [5,7] or as a means of reducing injection discomfort, TENS activates large diameter nerve fibres which have a lower threshold of response to electrical activity than smaller diameter fibres. This closes the central gating mechanismto small diameter nerve (that is pain) transmission [8]. The depth of needle penetration should not influence the efficacy of TENS if the method of action is closing the gate to peripheral pain perception by stimulation of larger diameter nerve fibres. Despite the theoretical basisfor the efficacy of TENS, its value in reducing the discomfort of intra-oral injections is debatable. An investigation of 101 injections (infiltrations and regional blocks) given by seven operators in association with the injection-assist system reported a reduction in injection discomfort in 74% of cases [9]. Another study [lo], using a different TENS machine, showed that when needle penetration was superficial, TENS was not as effective as sometopical anaestheticsin reducing injection discomfort. The TENS device usedin the present study was more effective than topical anaesthesia during regional block injections. These conflicting results could be due to the use of different TENS machines.Alternatively, the use of different surface preparationsto reduce discomfort during different types of injection may be warranted (for example topical application prior to infiltration anaesthesiaand TENS before deeperregional blocks). Although injection discomfort was significantly reduced by the use of TENS in the present study it was not completely eliminated. Although TENS is a potentially useful part of the dentist’s pain-control armamentarium,it is not suitable for use in all patient groups. It should be avoided in patients with demand-type pace-makers, in those with convulsive conditions and in individuals with any neurological disorder of the head and neck (such as trigeminal neuralgia). The safety of TENS in pregnancy has not been established. In conclusion, patient-controlled TENS reduced but did not eliminate the discomfort experienced during inferior dental and lingual block injections when compared with the use of 20% benzocaine topical anaesthetic.The use of the topical anaesthetic prior to inferior dental block anaesthesiadid not affect discomfort when compared with no mucosalpreparation.
References 111Rosivack
RG, Koenigsberg SR, Maxwell KC An analysis of the effectiveness of two topical anaesthetics. Anesth. Prog., 1990;37:290-292. [21 Quarnstrom F Electronic dental anesthesia. Anesth. Prog.,
1992;39:162-177. [31 Roberts DH, Sowray JH, Local analgesia in dentistry, Wright,
1987: 116-17.
3rd ed. Bristol:
420
J.G. Meechan
et alJJourm1
[4] Geissler PR, McPhee PM Electrostimulation in the treatment of pain in the mandibular dysfunction syndrome. J. Dent., 1986;14: 62-64. [5] Clark MS, Silverstone LM, Lindenmuth J et al. An evaluation of the clinical analgesia/anesthesia efficacy on acute pain using the high frequency neural modulator in various dental settings. Oral Surg., 1987;63:501-505. [6] Malamed SF, Handbook of local anesthesia, 4th ed. St Louis: Mosby, 1997: 292-3. [7] Donaldson D, Quarnstrom F, Jastak JT The combined effect of nitrous
of Dentistry
26 (1998)
417-420
oxide and electrical stimulation during restorative dental treatment. J. Am. Dent. Assoc., 1989;118:733-736. [S] Melzack R, Wall P Pain mechanisms a new theory. Science, 1965;150:971-979. [9] Burke FJT Dentist and patient evaluation of an electronic dental analgesia system for controlling discomfort of injections. Dent. Update, 1997;24:154-157. [lo] Meechan JG, Winter RA A comparison of topical anaesthesia and electronic nerve stimulation for reducing the pain of intra-oral injections. Br. Dent. J., 1996;181:333-335.