Comparison of Patient’s Comfort in the Anterior Palatal Anaesthesia Between Topical Anaesthetic Gel and Cryo-Anaesthesia Using Ice – A Split Mouth Randomized Controlled Trial.

Palatal injections continue to be one of the most painful injections, despite the advent of modern injection techniques. A wide array of techniques has been tried and tested to ease the pain using injections from time to time. This split-mouth study evaluated the efficacy of benzocaine gel and cryoanesthesia in reducing pain during palatal injection. This study was conducted for bilateral therapeutic maxillary premolar extractions and 40 patients were randomly selected for a split-mouth study with a total of 80 maxillary tooth extractions. In order to avoid any bias, a split-mouth technique was designed. It was found that cryoanesthesia was successful and had better patient compliance.

Keywords: Therapeutic premolar extraction, Palatal injection, Topical anaesthetic gel, Cryoanesthesia

Pain and anxiety during any injection are inevitable. Physicians have administered refrigerants as pre-injection anaesthetics for intramuscular and subcutaneous injections, vaccinations, establishing intravenous lines, and venipuncture. [1,2]

Local anaesthetics is the back bone for dental practitioners. Local anaesthesia is required in all dental practices including extraction, Trans alveolar extraction, Incision and drainage and many other minor surgical procedures. The main aim of the local anaesthesia is to prevent and to relieve pain. Injection of local anaesthesia is naturally causing pain and it is the main reason for anxiety amongst dental patients.[3] This pain gets further aggravated due to fear which is caused by the sight of needles and has been referred to as needle phobia or belonephobia. Topical anaesthetic agent before injection is widely advocated to minimize the pain of injecting local anaesthesia.[4]

The tissues in the palatal part are being tightly bound to the hard palate without tissue space present between it and the periosteum.[5] This induces the pain in the palatal part when the local anaesthetic is injected. Due to these reasons topical anaesthetic is applied on the palatal part before injection. Applying topical anaesthetics, pain is reduced while injecting which was followed from the 1980s. [6]

All Dental surgeons are considering ways to lessen the pain of palatal injection by various methods such as topical anaesthetic gel application,[7] cryo anaesthesia of the palate, [8] computerized injection systems,[9] pressure administration and transcutaneous electronic nerve stimulation (TENS). [10,11,12]. In this study we compared cryo-anaesthesia and topical gel (Benzocaine gel). Benzocaine is commonly used as a topical anaesthetic due to its prolonged action. [13,14,15] Cryo-anaesthesia is simply but it is application of ice in the localized region to block the nerve conduction of painful impulses in localized region.

The aim of this study is to compare patient comfort in the anterior palatal anaesthesia between topical anaesthetic gel and cryo anaesthesia using ice.

The study was conducted in the Department of Oral and Maxillofacial surgery, Adhiparaskathi Dental college and hospital, Melmaruvathur, India. After getting approval from the Ethical Committee and Review Board of the Institute. A total 40 patients requiring therapeutic extraction of first premolar for undergoing orthodontic management were selected and taken in the study. Split mouth study was done to eliminate bias. As anxiety and pain experience may vary for patients undergoing removal of tooth for the first time. The procedure was explained to the patient and informed consent was collected.

40 participants were included in the study (16 males and 24 females). Inclusion Criteria for the study are Age limit between 12 to 35 years. Patients who are referred for extraction of tooth (Therapeutic Extraction) in the anterior maxilla undergoing orthodontic treatment. Exclusion criteria for the study are Patients allergic to local anaesthesia Pregnant and lactating female, patients with systemic diseases, mentally or physically affected individuals, patients with drug addiction and patients who are not co-operative for the entire study. Patients with underlying medical conditions.

Study was conducted into two groups 

Group I (Benzocaine gel group): 40 tooth extractions, with topical Benzocaine gel administered on the palatal aspect for a period of 1 minute. Then 2% lidocaine with adrenaline was injected in the palatal aspect. VAS and Wong Baker Facial Pain score was analysed immediately after administration of Local Anaesthetic.

Fig: 1. Application of Topical gel in Right side

Group II (Cryoanesthesia group): 40 tooth extractions, with topical Cryo anaesthesia (Ice pack made with syringe) was administered to the same patient on the opposite quadrant on the palatal aspect for a period of 1 minute. Then Lidocaine with 2% adrenaline was injected in the Palatal aspect. Pain was assessed by Visual Analog Scale (VAS) from 0 – 10.

To rule out bias to overcome dental anxiety due to first extraction experience split mouth study was designed, patients were allotted in such a way that both groups had patients with first extraction experience in equal numbers.

Fig: 2. Application of cryoanesthesia in Right side

Efficiency of pain is determined by VAS

Evaluation was done to every patient post operatively using Heft-Parker visual analog scale  figure 4

Fig 4: Evaluation of patient after Local anaesthesia

Statistical Analysis

Data was summarized with SPSS Software version 20.0

The study was conducted between 40 participants who came for therapeutic extraction. In that16 participants were male and 24 were female. The age group of the patients were from 17 – 30 years. We analysed pain in the palatal aspect in both the groups. Average lower value is 0.317 and upper value is 1.407. Topical anaesthetic gel has the mean value of 1.475 and for cryo anaesthesia mean value is 0.575. Mean difference was about 0.9.  Compared to benzocaine topical anaesthesia cryo anaesthesia has better outcome in terms of VAS and it was statistically different with P value of <0.001.

Table: 1

Table: 2

Palatal injections make the patient highly uncomfortable due to the thick palatal mucosa which is closely adherent to the underlying palatal bone. Palatal injections continue to remain one of the most painful injections despite the advent of modern injection techniques. As a dental surgeon various methods are used to reduce pain during injection. In this study, we evaluated and compared the patient comfort in the anterior palatal anaesthesia between topical anaesthetic gel and cryo-anaesthesia using Ice. Patients comfort was assessed using the VAS scale. [16,17,18,19]

Table 1 describes the VAS score between the two groups. There was a statistical difference in VAS score between the two groups and cryo-anaesthesia was found to be better.

The advantage of cryo-anaesthesia is that it first acts on all the cells and thereby produces an anaesthetic effect effectively. The time for application of the cryo-anaesthesia was 1 minute.  Though the application of cryo-anaesthesia is very short, this helps to achieve comfort to the patient while penetrating the needle and the patient was comfortable. [20,21,22]

The cryo-anaesthesia has a shorter application time for about less than 1 minute compared to the topical gel which has more than 1 minute (0 – 2 min). Application of the cryo-anaesthesia is made easier compared to the topical gel as it mixes with the saliva intraorally. On the contrary topical gel has an altered taste sensation and patient found it difficult and few patients had discomfort in tolerating anaesthetic gel.

The Lewis hunting reaction, also known as the hunting response, is a cycle of vasoconstriction and vasodilation in exposed extremities. The phenomenon was initially described in 1930 by Thomas Lewis, who gave it the name Lewis reaction. Vasoconstriction first happens in order to stop heat loss, but it also causes a significant cooling of the extremities.[23] The blood arteries in the extremities will abruptly vasodilate five to ten minutes into the cold exposure. This is likely brought on by an abrupt reduction in the neurotransmitter release from the sympathetic neurons to the muscular coat of the arteriovenous anastomoses as a result of the local cold. This vasodilation brought on by the cold raises blood flow, which in turn raises the temperature of the fingers.[24]

Cryo-anaesthesia is found to be more effective in this study when compared to topical benzocaine gel. The use of the cryo-anaesthesia is low cost, easy to prepare, and safe for patient without any chemicals. The pain on delivery of anaesthesia may be numbed due to the effect of cooling of the entire thickness of the palatal tissue unlike in topical anaesthesia which acts only the overlying mucosa and submucosa. [25,26,27] This shortcoming is overcome by cryo-anaesthesia. These simple efforts by the dental surgeon can definitely make the patient more comfortable during palatal injection.

Although topical anaesthetic gel is used commonly, depth of penetration in topical anaesthetic gel ranges from 2 – 3 mm intraorally following application for 30 minutes. [28,29,30] Otherwise only overlying layers of mucosa gets anesthetized resulting in pain while injecting at the desired tissue plane.

Cryoanesthesia is the valuable technique for dental surgeons for reducing pain in the palatal aspect and it is a patient friendly too.  Further studies should be made to evaluate the efficiency of reducing the pain in the palatal aspect.