Year : 2021 Month : June Volume : 10 Issue : 23 Page : 1751-1755

Assessment of Pain Perception in Paediatric Patients on Application of Cooled and Uncooled Topical Anaesthetic Gel before Infiltration Anaesthesia - A Pilot Study

Prathyusha P.1, Amith Adyanthaya2, Marium Raheema3, Swetha S. Nair4, Aparna Sivaraman5, Risana K6, Nazreen Ayub K7, Reshma Aloysius8

1, 2, 3, 4, 5, 6, 7, 8 Department of Paediatric and Preventive Dentistry, KMCT Dental College, Mukkam, Calicut, Kerala, India.


Dr. Swetha S. Nair, Department of Paediatric and Preventive Dentistry, KMCT Dental College, Mukkam, Calicut, Kerala, India.
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Topical anaesthesia is fundamental in enhancing pain control during the process of dental injections. The study compared the effect of cooled and uncooled topical anaesthetic gel before infiltration anaesthesia in assessing pain perception in paediatric patients undergoing dental treatment procedures.



This is a split-mouth study where 16 children aged between 8 and 10 years who required bilateral local anaesthesia administration for various dental procedures were selected. Before infiltration anaesthesia, topical anaesthetic gel cooled to 40 C was applied on one side in the first visit followed by application of uncooled gel on the contralateral side in the subsequent visit. The patients were asked to individually rate their pain experience on each side using the Wong-Baker Faces Pain Rating Scale (WB-FPRS). Anxiety was assessed using pulse oximeter and FLACC scale (face, legs, activity, cry, and consolability). Data was analysed statistically using the paired ‘t’-test and a P value less than or equal to 0.05 was considered as statistically significant.



Patients reported less pain on Wong-Baker Faces Pain Rating Scale by using cooled topical anaesthetic gel. Discomfort and anxiety levels were also seen to be low when assessed using pulse oximeter and FLACC Scale for the same group (P < 0.05).



Cooling the soft tissue site with anaesthetic gel helped reduce pain perception during infiltration in children and was seen to be a more feasible technique. Hence this technique can be used as a successful adjunct to the local anaesthesia administration prior to dental procedures.



Anaesthesia, Cooling, Topical Gel, Injection, Pain


Paediatric dentistry emphasizes primarily on local anaesthesia (LA) as the front runner to minimize pain perception during dental procedures. Even with continuous development in new techniques for dental injections, this procedure still causes pain and discomfort and is often described as a major reason for dental anxiety. Studies on topical anaesthesia are quite common in dentistry but with varying results of their outcome. Successful behavior management of the child can be achieved by topical treatment of the tissues to perceive minimum pain during injection of LA. Various methods have been employed to minimize pain perception in children like cooling the topical gel, vibrotactile devices such as Vibraject1 and Dental Vibe2 that provide mechanical vibrations to the surrounding tissues and act as counter stimulation. These advanced techniques involve high cost, and the complexity of the equipment might further aggravate the child’s anxiety and fear.

Application of topical gels does not always guarantee pain free injections, and the numbing effect is dependent on several factors such as speed of injection and gauge size of the needle.3 Authors have also stated that anaesthetic gels only relieve pain caused by the needle insertion and not of the actual injection.4 Different types of topical gels (e.g. lidocaine, prilocaine or benzocaine) are used before dental procedures in recent times.

Cooling the tissues has a long standing history in medicine. The technique of local external cooling has been in use for treating musculoskeletal pain, fractures, sports injuries, sprains, etc. Studies on topical cooling of oral tissues are limited in dentistry. Although the concept of cooling the soft tissue prior to injection procedures is established, the literature lacks such kind of application in paediatric dental procedures. A study from 1989 reported how the use of ice for cooling on the palate before and during local infiltration anaesthesia relieved discomfort, but no other method of topical anaesthesia was compared to this cooling effect.5 Another study revealed that cooling was an effective adjunct to conventional topical anaesthesia but the efficacy of ice as the primary anaesthetic agent was not evaluated.6 The mechanism of action for cooling was found to be due to stimulation of myelinated A fibers and in turn activating inhibitory pain pathways.7 Furthermore, it was seen to cause decrease in the activation threshold of tissue nociceptors and conduction velocity of nerve signals conveying pain and thereby causing cold-induced neuropraxia.




  • To introduce a cost-effective method which is less technique - sensitive but clinically very effective and can replace the traditional methods of inducing local anaesthesia.
  • To assess and compare the pain perception on   application of cooled and uncooled topical anaesthetic gel during infiltration anaesthesia.
  • To assess the pain perception of the patient during dental injections using Wong Bakers Faces Pain Rating Scale in both experimental groups.
  • To compare change in Pulse rate and SpO2 levels before and after injections using both cooled and uncooled topical gel.
  • To evaluate patients based on FLACC scale after the injection procedure of application of both cooled and uncooled gel.


This is a cross-sectional observational study which was conducted from February to April 2019. The study was conducted in the Department of Paediatric Dentistry after obtaining ethical clearance (IEC / IRB No: KMCTDC / IEC / 2019 / 12). Parents or guardians of the selected subjects were provided with complete details of the study, who willingly allowed their children to participate in the study after signing the consent form. 16 children aged between 8 and 10 years fulfilling the inclusion criteria were selected for the study.



Inclusion Criteria

  1. Patients requiring local anaesthesia for dental extraction of retained maxillary anterior teeth on either side.
  2. Cooperative patients (Frankel’s behavior rating scale: positive and definitely positive)
  3. Healthy patients (ASA 1) who were aged between 8 and 10 years.



Exclusion Criteria

  1. Medically compromised patients
  2. Patients with history of allergy to anaesthetic agents
  3. Patients with swelling, pain or periapical pathology
  4. Patients with uncooperative behaviour.



All patients, who reported to the Department of Paediatric dentistry and were suitable according to the above mentioned criteria were subjected to the procedure at two visits. Local anaesthesia was administered after application of local anaesthetic gel – Stim Lidayn Oraspot gel (benzocaine 20 %) on the oral mucosa. On the test side of oral mucosa, cooled gel was applied at the first visit prior to the dental injection whereas on the contralateral side anaesthetic gel at room temperature served as the control. All the participating children and their guardians were informed regarding the technique to be performed and consent was obtained. Patients were familiarized with Wong bakers pain rating scale(Figure1), Pulse oximeter (Apex medical systems Hyderabad, India) (Figure 2) and FLACC scale that were used to assess the pain perception after pricking. The tell show do method and communication were used for behavior modification of these children during the procedure. The quadrants were allocated to control and study group according to simple randomization. The soft tissue site was dried with a sterile gauze before application of the anaesthetic gel. The benzocaine 20 % gel was cooled and maintained at 40 C. A pepper-corn sized topical anaesthetic gel (Figure 3, 4) on 1 cm2 area of the tissue was applied using a cotton pellet for 1 minute and needle was then positioned and slowly inserted. The same procedure was followed for uncooled gel, maintained at room temperature. Injection of 1.5 ml of Warren Lignox lignocaine 2 % A with 1:80000 adrenalin using a 24 gauge needle (Dispovan, India) was administered after negative aspiration gradually over 20 ‒ 30 seconds for infiltration. Pain or discomfort was graded by the patient on the Wong bakers pain rating scale by pinpointing a particular face that best described their pain perception. The WB-FPRS consists of six drawn figures indicating a range from ‘no hurt’ to ‘hurts worst’ (Figure 5). The children were assessed by pulse oximeter (index finger of left hand) and Face Legs Activity Cry Consolability scale prior to and also after the injection procedure.