Effect of photobiomodulation on pain perception during local anesthesia in children: a systematic review and...

Pain associated with anesthetic injections is a significant concern in pediatric dentistry and is often linked to dental fear and anxiety. Photobiomodulation (PBMT) may reduce pain symptoms in children during local anesthesia administration. This systematic review aimed to evaluate the current scientific evidence on the effectiveness of PBMT in reducing pain during local anesthesia administration in children. Data search was conducted in PubMed, Web of Science, Scopus, Cochrane CENTRAL, Embase, and BVS-MedLine/LILACS up to January 2025, without restrictions on language or year of publication. Two independent reviewers performed the data extraction and assessed the risk of bias (ROB-2 tool). A meta-analysis was performed, and the mean difference (MD), standardized mean difference (SMD), and 95% confidence interval (CI) were calculated. The strength of the evidence was also assessed. The electronic search identified 9,852 records, of which 10 studies met the eligibility criteria and were included in the qualitative synthesis. The analyzed studies employed different PBMT parameters, varying in wavelengths and energy densities. The meta-analysis included studies with placebo or topical anesthetic gel as control groups, and measured pain outcomes using the WBFPRS and FLACC scales. All included studies measured pain at the moment of needle insertion. Three studies comparing PBMT with a placebo, which contributed 14 comparisons. These studies demonstrated a moderate reduction in pain in favor of PBMT (SMD = -0.44; 95% CI: -0.59 to -0.29; I² = 0%), indicating a moderate effect favoring the intervention with consistent results across all scales. A sensitivity analysis confirmed the stability of the findings. A second meta-analysis of two split-mouth studies comparing PBMT with topical anesthetic gel demonstrated a large and significant reduction in pain with PBMT (MD = -3.30; 95% CI: -3.98 to -2.62, I² = 0%). PBMT may be beneficial in reducing pain during local anesthesia in children, although the current evidence remains limited. Further well-designed trials with standardized protocols are needed to strengthen the evidence and better inform its clinical applications. The review protocol was registered in PROSPERO under CRD42024539486.