Challenges in Evaluating the Analgesic Effects of Photobiomodulation in Dentistry: A Narrative Review

The purpose of this narrative review is to explore the challenges and limitations in the methodologies for evaluating the analgesic effects of photobiomodulation in dentistry. The literature published up to April 2025 in the English language was sourced from online databases and reference lists; search engines included Medline, PubMed, Embase, Scopus, and Google Scholar; the relevance of papers was discussed by two reviewers; and a total of 42 publications were included in this narrative review. If there was disagreement between the two reviewers, a third one moderated the selection process. Photobiomodulation has emerged as an alternative to traditional pharmacological analgesia in dentistry. Both lasers and light-emitting diodes can be used to modulate cellular responses, showing promising results for pain reduction in the oral cavity, particularly in the dental pulp and mucosal soft tissues. However, evaluating analgesic effects remains challenging due to variations in light sources, parameters, delivery modes, and target sites. Additionally, inconsistencies in study methodologies such as pain assessments, placebo effects, pain conditioning, and the presence of non-responders further complicate interpretation. Other variables, such as differences between hard and soft tissues, also contribute to variability. Photobiomodulation (PBM) shows promising potential as a non-invasive analgesic approach in dentistry. However, its integration into clinical practice remains uncertain due to variability in study methodologies, inconsistent reporting of treatment parameters, and a lack of standardized outcome measures. Consequently, the clinical significance of PBM results can vary widely, ranging from meaningful analgesic effects in some studies to minimal or non-significant effects in others. The absence of standardized PBM guidelines in dentistry continues to be a major barrier to its consistent implementation.