Effectivenessof electronic dental anesthesia for restorativecare in children Shiu-yinCho, BDS, FRACDS Bernadette K. Drummond, BDS,MS, PhD, FRACDS MichaelH. Anderson,BSc, MBChB, DipObs, Dip AV Med, Dip IH, MRNZCGPSheila Williams BSc(Hons) Abstract mission. The gate control theory states that activity Theeffectiveness of electronic dental anesthesia(EDA) generated by myelinated primary afferent fibers (the A fibers) inhibits the transmission of activity in the for pain control duringrestorative procedureswas compared with local anestheticinjection (LA) in 32 children aged small unmyelinatedprimary afferent fibers (the C fi- bers),6 acting via inhibitory circuits in the dorsal horn. to 12years. Eachchild selected had two antimereprimary In addition to activating local inhibitory circuits, one or permanentmolars requiring similar-sized Class I or Class II restorations.The pain levels duringrestorative treatment possible explanation for the effectiveness of TENSis that the electrical stimulationcauses release of pituitary wereassessed using a visual analoguescale. Heartrates and and hypothalamic opioid peptides into the systemic behaviorwere also recorded.A crossoverdesign was used with circulation or into the cerebrospinal fluid. 7 Another eachchild actingas his/her owncontrol. Theresults showed theory is that serotonin, dopamine,and nor-adrenalin, that overall, EDAwas less effective thanLA for cavity prepa- which may have roles in the effects of electrically ration. Thereported pain scores for EDAwere higher in per- produced analgesia, are produced.8 Drugs affecting manentteeth for the deepercavities, and with one of the these neurotransmitters have been shown to alter operators.The pre- or post-treatmentanxiety scores were not analgesia produced by stimulation or opioids. The foundto differ significantly betweenthe two restorativeap- exact mechanismof TENSremains unknownand may pointments.However, children with the highestpretreatment be a combinationof one or moreof the theories. Woolf scoreswere more likely to reporthigherpain scores with EDA. and Thompson6 believe that the most likely mecha- Despite this, 63%of the children preferred EDAto LA. nismis the activation of segmentalinhibitory circuits Dentalanxiety, cavity depth, the tooth beingtreated, and in the spinal cord supplementedby descendinginhibi- operatorattitude mayalso be importantfactors in determin- tory pathways. ing the success of EDA.(Pediatr Dent20:2 105-111, 1998) Effectivenessofelectronic anesthesia indentistry ain control is an important part of pediatric TENSdevices have been used to control the pain dentistry. Althoughmost children can cope with of trigeminal neuralgia or atypical facial pain, and to p local anesthetic injections, a few children are relieve* musclespasms in myofascialpain dysfunction. Resultsof clinical studies are limited and extremelyvar- needle-phobic, and giving them an injection presents x’ a challenge to the dentist. For other children, the ied. 2 In the mid-1980s,several devices weredeveloped paresthesia which may linger for hours after the for dentistry. These were TENSunits modified for 9 completion of the dental procedure is more intraoral use. Malamedet al. used the term electronic objectionable than the injection. In the past decade, dental anesthesia (EDA)when referring to the appli- there has been renewedinterest in the applications of cation of TENSto dentistry. In their study, they electronic pain control in dentistry and several elec- reported a success rate of morethan 80%for shallow tronic dental anesthesia machinesare currently being and moderatelydeep restorations. The success rate for advertised and used. deep restorations was 60%. The EDAdevice is a modified TENSunit which uses lower currents and Mechanismofaction of transcutaneous higher frequencies. electricalnerve stimulation Onereported indication for EDAis for needle-pho- In 1967, Shealy4’ 5 first introducedthe use of trans- bic children even thoughonly a few studies have tested cutaneous electrical nerve stimulation (TENS)to help its effectiveness in children. In a double-blindstudy of control chronic pain. The explanation of the mecha- the effect of EDAin 30 children using electric pulp testing and rubber dam clamp application as the nism by which TENSproduces anesthesia is based on 1° several theories describing mechanismsof pain trans- stimuli, Abdulhameedet al. found a significant rise Pediatric Dentistry-20.’2, 1998 AmericanAcademy of Pediatric Dentistry 105 in the pain threshold when EDAwas used. The sub- Dunedin, NewZealand. After obtaining approval from jective pain scores of the children and the assessment the Southern Regional Health Authority Ethics Com- of the children’s pain levels by the investigator werenot mittee, 32 healthy children aged 6-12 years who had significantly different from measurements when an two primary or permanentantimere molars with simi- inactive machinewas used. Harveyand Elliot ~ evalu- larly sized carious lesions wereselected. Theteeth had ated pain perception in 20 children during Class I no recorded history of trauma or pulpitis. Informed amalgampreparations on permanent mandibular first written consent wasgiven by the parents and the chil- molars. They reported a significant decrease in pain dren were invited to take part and give their assent. perception with EDAcompared with a placebo inac- Dental treatment was provided by three dental thera- tive machine. Reported pain with EDAincreased when pists (school dental nurses) trained by the principal deeper cavity excavation was necessary. investigator to use the 3MDental Electronic Anesthe- teDuits et al. 12 comparedthe effectiveness of EDA sia System8670. with conventional local anesthesia for restorative pro- A crossover study design was used. The antimere cedures in 27 6- to 12-year-old children. Theyfound teeth were restored in two separate visits with random no significant differences betweenthe effectiveness of selection of use of EDAor LA. The principal investi- EDAand local anesthesia. The dental procedures were gator was present at each appointment to ensure the rubber damapplication and preventive resin restora- set procedures were followed and to record the obser- tions, which maybe painless without anesthesia. In vations and measurements. For the control visits, another study, Jedrychowskiand Duperon~3 tested the anesthesia wasgiven by infiltration for the maxillary effectiveness of EDAin restorative procedures on 40 teeth and inferior nerve block for the mandibularteeth. children. Only two children reported moderate dis- Throughoutthe study, local anesthesia was referred to comfort requiring injection of local anesthesia to as sleepy juice ("shot" is not a term knownby these completetreatment. These two children still reported children). Cavity preparation beganafter 5 min. Injec- discomfortafter local anesthesia. tions wererepeated if the anesthesia wasnot effective. Recently, the 3M company introduced an EDA EDAwas referred to as using the "funny stickers" device whichuses extraoral electrodes (3MDental Elec- throughout the study. Whenusing EDAfor mandibu- tronic Anesthesia System 8670). The extraoral lar primary teeth, the electrodes wereplaced over each electrodes eliminate the inconveniences of intraoral mental foramen and for mandibular permanent mo- electrodes such as difficulty in application, obstructed lars, they were placed over the apices of the last molar field of operation, and easy detachment. Croll and and over the mental foramenipsilaterally, with at least Simonsen~4 reported use of the system in 45 children 0.5 in in between. For maxillary primary molars, the aged 3 to 13 years. Thirty-seven children having pro- electrodes were placed over the apices of the primary cedures including extraction of primary teeth with molars just below each zygoma and for permanent resorbing roots or Class II restorations were success- maxillary molars the electrodes were placed over the fully treated with EDAalone. No control group was apices of the last molar and just belowthe ipsilateral used. Morerecently, Segura et al. 15 investigated the zygoma,with at least 0.5 in in between. effectiveness of EDAfor "moderate" procedures (14 The EDAmachine was set to the maximumfre- Class II restorations and one stainless-steel crown)in quency (140 Hz) and pulse width (2501~s) primary molars of 15 children aged 7 to 12 years. The recommendedby the manufacturer. A pilot study car- children’s past experiences with restorative procedures ried out prior to the main study established that under local anesthesia were used as the control. Mini- acceptance was greatly improved when the children mal pain was reported in most procedures and 14 of were allowed to control their owncurrent output. The the 15 children said they preferred EDAto local anes- children were asked to increase the output from the thesia. Sasa and Donly~6 comparedthe effectiveness of EDAuntil they felt significant tingling. The amplitude EDAto local anesthesia in 17 children aged 6 to 14 was reduced slightly for 20 s with the principal years. Theprocedures included Class II restorations or investigator’s guidance and then gradually increased stainless-steel crowns with and without pulpotomies. again until there were signs of involur~tary muscle Sixty percent, of the patients stated that they preferred movementsnear the electrodes. The amplitude was LAto EDA,which was only abandonedin four cases. kept at this level if the child reported they were com- Of the children who preferred LA, 70%received re-