Title Larger 25-Gauge Needles Do Not Cause Increased Inferior Alveolar Nerve Block Injection Pain as Compared to Smaller 27- or 30-Gauge Needles
Clinical Question In patients requiring inferior alveolar nerve block, does a larger gauge needle cause increased injection pain as compared to smaller gauge needles?
Clinical Bottom Line Larger gauge needles do not cause increased injection pain for inferior alveolar nerve blocks (IANBs) as compared to smaller size needles. This was supported by two blinded, randomized controlled trials with a total of 1,068 injections to 948 patients requiring anesthesia for dental treatment. Flanagan et al. evaluated IANB and infiltration injections in adults, whereas Brownbill et al. evaluated only IANBs in children. This conclusion is important because many dentists may believe a smaller needle would produce less injection pain and therefore choose a smaller size; however, smaller dental needles may be more prone to breakage which is a rare but very serious complication.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
17511363Flanagan/2007810 adultsRandomized Controlled Trial
Key resultsThe patients in this study were randomly assigned and blinded to a 25- or 27-gauge needle used for inferior alveolar nerve block, maxillary infiltration, or palatal infiltration. After injection, the rated their pain experience using a visual analog scale (VAS). The frequencies of pain level (0-10) were compared between groups. Additionally, no difference was noted between injection side, injection location, gender, treating dentist, injection side, or overall. Chi-squared statistic was used to compare pain level frequencies among the groups.
3481519Brownbill/1987138 childrenRandomized Controlled Trial
Key resultsThe patients in this study were randomly assigned and blinded to 25- or 30-gauge needle used for inferior alveolar nerve block. They immediately reported their pain experience on a visual analog scale (VAS). There was no difference in pain between the groups per the Wilcoxon rank sum test (W = 4088, z = 0.95, p = 0.34). Additionally, there was no difference based on age, sex, effectiveness of anesthesia, or rate of positive aspiration.
Evidence Search ("inferior alveolar" OR "inferior dental") AND (needles OR needle) AND gauge AND pain
Comments on
The Evidence
Although both RCTs blinded the patients, it is impossible to completely blind the operator since different needle gauges may have a different feel during soft tissue penetration or during injection. All subjects were randomized to the treatment group, although neither study described how this was done. Also, each patient only received one injection versus an ideal split-mouth design which would permit direct comparison. Neither study comprehensively described demographic factors of each group except their biologic sex and age. A topical anesthetic was used (Brownbill/1987) which may have masked any difference between the two groups, although this is common in clinical practice. And finally, neither study mentioned pre-operative pain nor considered pre-operative pain conditions as an exclusion criterion.
Applicability Since IANBs are commonplace in general dentistry, this evidence is applicable to any specialty performing local anesthesia for children or adults. Cost is not a significant factor because there is not a significant cost difference between different needle gauge sizes. Since larger dental needles offer some advantages (more “feel” during injection, low risk of breakage, least amount of deflection) and do not result in increased injection pain, this may be an attractive choice over the smaller gauge choices.
Specialty (Endodontics) (General Dentistry) (Oral Surgery) (Pediatric Dentistry) (Periodontics) (Prosthodontics) (Restorative Dentistry)
Keywords Dental injection, pain, needle size, needle gauge
ID# 3506
Date of submission 11/26/2022
E-mail phares@livemail.uthscsa.edu
Author Bradley J. Phares, DDS
Co-author(s) Mary Namy, DDS
Co-author(s) e-mail namy@livemail.uthscsa.edu
Faculty mentor Asma Khan, PhD, BDS
Faculty mentor e-mail khana2@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available