|Year : 2017 | Volume
| Issue : 2 | Page : 34-38
Evaluation of a modified two-stage inferior alveolar nerve block technique: A preliminary investigation
Ashwin Rao1, Deepti Thakkar1, Arathi Rao1, YM Karuna1, N Srikant2
1 Department of Paedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India
2 Department of Oral Pathology, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India
|Date of Web Publication||11-May-2017|
Department of Paedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: The two-stage technique of inferior alveolar nerve block (IANB) administration does not address the pain associated with “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the injection. This study evaluated a “modified two stage technique” to the reaction of children during “needle insertion” and “local anesthetic solution deposition” during the “first stage” and compared it to the “first phase” of the IANB administered with the standard one-stage technique. Materials and Methods: This was a parallel, single-blinded comparative study. A total of 34 children (between 6 and 10 years of age) were randomly divided into two groups to receive an IANB either through the modified two-stage technique (MTST) (Group A; 15 children) or the standard one-stage technique (SOST) (Group B; 19 children). The evaluation was done using the Face Legs Activity Cry Consolability (FLACC; which is an objective scale based on the expressions of the child) scale. The obtained data was analyzed using Fishers Exact test with the P value set at <0.05 as level of significance. Results: 73.7% of children in Group B indicated moderate pain during the “first phase” of SOST and no children indicated such in the “first stage” of group A. Group A had 33.3% children who scored “0” indicating relaxed/comfortable children compared to 0% in Group B. In Group A, 66.7% of children scored between 1–3 indicating mild discomfort compared to 26.3% in group B. The difference in the scores between the two groups in each category (relaxed/comfortable, mild discomfort, moderate pain) was highly significant (P < 0.001). Conclusion: Reaction of children in Group A during “needle insertion” and “local anesthetic solution deposition” in the “first stage” of MTST was significantly lower than that of Group B during the “first phase” of the SOST.
Keywords: Inferior alveolar nerve, injection, nerve block
|How to cite this article:|
Rao A, Thakkar D, Rao A, Karuna Y M, Srikant N. Evaluation of a modified two-stage inferior alveolar nerve block technique: A preliminary investigation. Dent Hypotheses 2017;8:34-8
|How to cite this URL:|
Rao A, Thakkar D, Rao A, Karuna Y M, Srikant N. Evaluation of a modified two-stage inferior alveolar nerve block technique: A preliminary investigation. Dent Hypotheses [serial online] 2017 [cited 2019 Jul 17];8:34-8. Available from: http://www.dentalhypotheses.com/text.asp?2017/8/2/34/206098
| Introduction|| |
Local anesthetic administration in young children is a challenging procedure. When given gently and carefully, it lays the foundation for a cooperative child. But if administered carelessly, it can result in severe child anxiety. Thus, every possible effort should be made to administer painless local anesthetic injections in children. This might necessitate modification of the existing conventional techniques depending on the skill, confidence, and personality of the clinician., However, while the available scientific evidence has generally focused on sedation and general anesthesia as primary pharmacologic modes for alleviating dental anxiety of children, the techniques of painless local anesthetic administration specific to children have not received sufficient attention.
The inferior alveolar nerve block (IANB) has been associated with pain and discomfort. To overcome these factors, a two-stage injection has been suggested by various authors.,,, The first phase involves insertion of the needle submucosally followed by deposition of 0.3 to 0.4 ml slowly over 60 seconds. After 4 to 5 minutes, in the second phase the needle is reinserted gently to the adequate depth and about 1–1.5 ml of the solution is deposited. This technique of injecting in two stages helps the clinician make a painless entry into the pre-anesthetised submucosa. While most of the literature describes the two-stage technique in adults, the evidence for its efficacy in children is lacking. Recently, in one study done on children, the authors have reported that, the two-stage technique is a practical alternative to conventional injections in reducing pain for all intra oral injection techniques including the IANB in children. However, the two-stage technique does not address the pain associated with “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the injection. Moderate to severe pain has been reported to range between 14–22% during needle insertion and between 20–40% during the deposition of the anesthetic solution at the target site., To minimize the pain on injection, the use of topical anesthesia, low-pressure injection, narrow sharp needles, a slow injection rate, and solutions that are warmed and buffered have been suggested in the literature. Out of these available options, though the topical anesthesia is widely used, it’s efficacy in reducing pain associated with the intraoral injection of local anesthesia is questionable.,,
It has been suggested in literature that syringes with extra-short, 30-gauge needles are appropriate for infiltration injections. Thus, while using the two-stage IANB technique, insulin syringes with ultrashort 30-gauge needles may be used to infiltrate a small amount of the local anesthetic solution in the first stage before a larger needle is introduced in the second stage.,
No study to our knowledge has evaluated the effectiveness of this technique in children. Hence, the objective of this study was to comparatively evaluate the reaction of children during “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the IANB using a modified two-stage technique with the “first phase” of the standard one-stage technique.
The null hypothesis was set as there will be no difference in the reaction of children during “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the modified two-stage technique compared to the “first phase” of the IANB administered with the standard technique.
| Materials and Methods|| |
The study was initiated after obtaining the Institutional Ethical Committee clearance. The protocol reference number was 12055. Informed consent explaining the rationale of the study was read and signed by the parents of the children selected for the study. The study was conducted in strict adherence to the guidelines by Helsinki Declaration of 1975 (revised in 2000).
This was a parallel group single-blinded comparative in vivo study. The children participating in the trial were blinded to the technique and purpose of the IANB’s administered to them.
Children between 6 and 10 years of age in whom an IANB was indicated for any dental procedure and with no prior experience of an intra-oral injection were included in the study. Children who had significant medical problems [American Society of Anesthesiologists (ASA) III or greater], extremely uncooperative children, and children who had taken CNS depressants or any analgesic medications within 8 hours before the treatment were excluded from the study.  Children who reported with severe pain were also excluded from the study as that could affect the reaction of children.
A total of 34 children who fulfilled the inclusion criteria were randomly divided into groups; group A (modified two-stage IANB technique) and group B (standard one-stage IANB technique) with simple randomization using the coin flip method. Randomization was done using a coin flip by an independent person not involved in the study. At the end of the randomization process, group A comprised 15 children and group B comprised 19 children.
Interim results with 34 children, based on the table of fishers exact test [Table 5], showed the number of children in group A and group B in the relaxed (during the injection process)/comfortable category [of Face Legs Activity Cry Consolability (FLACC) scale, explained later] to be 5 and 0, respectively. Similarly, the number of children in the mild discomfort category in group A and group B were 10 and 5, respectively, and in the moderate pain category were 0 and 14 in group A and group B. Based on this, we arrived at an effect size of 0.7761. A sample size of 34 achieves 99% power to detect an effect size (W) of 0.7761 using 2 degrees of freedom Fishers Exact Chi-Square Test with a significance level (alpha) of 0.05000. Effect Size = ad/bc (odd ratio formula when data is binary). The observer was asked to stand outside the direct vision of the child, but close enough to enable accurate observations. The obtained data was statistically analyzed using Fishers Exact test with the P value set at <0.05 as level of significance.
The recommended injection protocol in children which includes basic behavior management techniques like Tell Show Do, distraction, euphemisms, positive verbal reinforcements were followed for both the groups. A flavored topical anesthetic (Precaine topical anesthetic gel, Pascal international, Inc., Bellevue, USA) was applied to the area of injection for 5 minutes. All the injections were administered by an experienced operator well trained in either of the two techniques, but who was not involved in the study. The allocation sequence was concealed from the operator in sequentially numbered opaque sealed envelopes.
The local anesthetic solution used was 2% lidocaine with 1:200,000 adrenaline (Xylocaine 2%, AstraZeneca Pharma India Ltd., India).
The modified two-stage technique was administered as follows.
Syringes used were a 1-ml insulin syringe, (U-40 insulin syringe, Dispo van, Hindustan syringes and Medical devices Ltd., India) and a 2-ml disposable syringe with a 26 gauge × 1½ inch needle. (Unolok, Hindustan syringes and Medical devices Ltd., India)
In stage one of the injection, the insulin syringe loaded with 0.4 ml of the local anesthetic solution was used. The needle penetration to the injection site was from the same side of the mouth. The bevel of the needle was kept firmly against a taut cheek mucosa. The cheek mucosa was then stretched and pulled over the needle to about 2 mm. No attempt was made to push the needle into the mucosa.
With about 2–3 mm of needle insertion into the mucosa, a very minute quantity of the anesthetic solution, i.e., approximately 0.25 units (the U-40 insulin syringe has 40 units in one ml) was deposited. After a gap of 2–3 seconds, another 0.25 to 0.5 units of local anesthetic was gently deposited. This cycle of injecting small amounts of the anesthetic solution was continued till almost the entire length of the ultrashort needle was into the mucosa and till 0.2 ml of the local anesthetic solution was simultaneously deposited. Now, following aspiration, the remaining solution was deposited slowly. The time taken for the entire first phase of the injection was around 80 to 120 seconds. Three to four minutes to the first phase of the injection, 1 ml of local anesthetic solution was deposited with a 2-ml disposable syringe using the standard IANB technique.
The standard one-stage inferior alveolar nerve block was administered as follows:
A 2-ml disposable syringe (Unolok, Hindustan syringes and Medical devices Ltd, India) with a 26 gauge × 1½ inch needle was used. After initial needle penetration to a depth of 2–3 mm, the same needle was gently advanced to the target site until bone was contacted. After this, 0.4 ml of the local anesthetic solution was gently deposited as the needle was advanced. At the target site, 1 ml of the solution was deposited slowly over one minute time period.
The reaction of the children to IANB was evaluated by an independent calibrated observer who was not aware of the study design or purpose. The observer was not blinded to the injections. Only the “first stage” of the modified two-stage technique was evaluated against the “first phase” of the standard one-stage technique for the reaction of children during “needle insertion” and “local anesthetic solution deposition”. The first phase of the standard one-stage technique was the phase where “the 26-gauge needle was initially inserted to a depth of 2–3 mm and advanced to the target site until bone was contacted and 0.4 ml of the local anesthetic solution was deposited”. Evaluation was done objectively using the Face Legs Activity Cry Consolability (FLACC) scale [Table 1].
| Results|| |
The characteristics of the study groups are shown in [Table 2]. Comparison of the age between the two groups was done using independent student’s t-test [Table 3]. Gender comparison done using chi-square test [Table 4] showed that there is no statistically significant difference in gender between the two groups. Out of the 15 children in group A, 5 children (33.3%) scored 0 in the FLACC scale indicating relaxed/comfortable injection experience. Ten children (66.7%) in group A got a FLACC score of 1 indicating mild discomfort during injection. In group B, out of the 19 children, three children (15.8 %) got an FLACC score of 3 indicating mild discomfort. Nine (47.4%), 5 (26.3%), and 2 (10.5%) children in group B scored 4, 5, and 6, respectively, indicating moderate pain.
Cross tabulations of groups and pain scores done using Fishers Exact test [Table 5] showed that 73.7% in group B scored between 4 and 6, during the “first phase” of the standard one-stage technique indicating moderate pain. In the “first stage” in group A, none of the children indicated moderate pain. Group A had 33.3% children who scored “0” indicating relaxed/comfortable children compared to 0% in group B. A total of 66.7% of children in group A scored between 1 and3, thus indicating mild discomfort compared to the 26.3% in group B. The difference in scores between the two groups in each category (relaxed/comfortable, mild discomfort, moderate pain) was highly significant (P < 0.001).
The reaction of children in group A during “needle insertion” and “local anesthetic solution deposition” in the “first stage” of the modified two-stage IANB technique was significantly lower than that of group B during the “first phase” of the standard one-stage IANB technique. Thus, the null hypothesis was disproved.
| Discussion|| |
According to Diana et al., IANB is “less unpleasant” and “children cry less” when a 30-gauge needle is used compared to a 27-gauge needle. Though the reduced reaction seen in our study during “needle insertion” in the first stage can be explained on basis of the fine 30-gauge needle of the insulin syringe, we also felt that the ultra-short 8 mm length of the needle gave better control to the operator during needle insertion. Though questions are often raised on the aspirating ability of the 30-gauge needle, recent guidelines by AAPD on use of local anesthesia for pediatric dental patients states that any 23- through 30-gauge needle may be used for intraoral injections, since blood can be aspirated through all of them.
Also, in the present study, no effort was made to push the needle through the mucosa. The cheek mucosa was stretched and pulled over the needle to about 2 mm. This sudden stretch of the mucosa is believed to lessen the discomfort associated with needle penetration based on the Gates control theory of pain, according to which a sudden stretch or manipulation of the mucosa, activates a greater number of large fibres (touch) that inhibit previously activated small fibres related to pain.
It should also be noted that during the needle insertion with the insulin syringe, the syringe approached the site of needle penetration from the same side of the mouth as opposed to the contralateral approach in the conventional one-stage IANB technique. In the contralateral approach, the tongue pushing the barrel of the syringe during the injection process can be a practical problem in young children. The same side approach overcomes the interference of the tongue during the needle insertion process thus contributing to reduced discomfort observed during needle insertion.
A large amount of local anesthetic solution suddenly injected leads to the discomfort because of the expansion of the subcutaneous tissue. Thus, Quaba et al. recommended using the smallest volume syringe available to obtain greater control and accuracy over the injection rate. Accordingly, the decreased pain perception during deposition of the local anesthetic solution in our study can be attributed to smaller diameter of the 1-ml insulin syringe barrel and plunger that allows deposition of very minute amounts of the local anesthetic solution.
A parallel design was adopted in our study as against the cross over trial design of the study on the two-stage technique in children by Sandeep et al.,  as we felt that a painful injection experience on one side could lead to bias during the second injection due to the subjective fear factor setting into the child. Also, the cross over design of the former study involved the process of blinding the child with a sham injection for the standard one-stage technique, which we felt would be unethical. We used an objective scale (FLACC scale) to evaluate the pain reaction in children as we felt that it could be unreliable if we use subjective scale in children, especially following a stressful procedure like a local anesthetic injection.
However, in the present study, the injections were administered to children of different age groups. Comparison of age using independent student’s t-test between the two groups showed that group B has significantly higher age of 8.8421 with P < 0.001. Though it can be considered as the confounding factor in the study, it has to be noted that the mean age in group A was 6.4 years. This group comprising of younger children showed lesser reaction to needle insertion and deposition of local anesthetic solution compared to children in Group B. Nevertheless, further studies are indicated evaluating the same research question in a specific age group of children. The control in this study was the “first phase” of the standard one-stage technique. In hindsight, we felt that the standard two-stage technique could have been a more valid control and this is another limitation of the study.
| Conclusion|| |
Under the conditions of the study, the reaction of children in group A during the “first stage” of the modified two-stage IANB administration during “needle insertion” and “local anesthetic solution deposition” was significantly lower than that of group B during the “first phase” of the standard one-stage IANB administration.
Local anesthesia is an important component of the “pharmacologic management repertoire” of the pediatric dentist along with sedation and general anesthesia. Methods of painless depositions of local anesthesia in children deserve more attention in literature. A comfortable local anesthetic experience can lay the foundation in any child to “A Positive Attitude towards Dentistry”.
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Conflicts of Interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]