Burning mouth syndrome (BMS) is a chronic orofacial pain disorder characterized by the symptom triad of burning sensation, xerostomia, and taste disturbance, all in the absence of specific mucosal lesions or laboratory findings [1,2]. It predominantly affects middle-aged and elderly women, with a prevalence of 1.73 % in the general population and 7.72 % in clinical settings of dental practice [3]. Patients with BMS often experience chronic discomfort that can escalate from a burning sensation to severe pain [4]. This condition can lead to emotional disturbances (e.g., anxiety and depression) [5,6], sleep disorders (e.g., insomnia and poor sleep quality) [7], cognitive impairments (e.g., declines in attention, working memory, and executive functions) [8], and a poorer oral health-related quality of life compared to controls [9]. Thus, investigating long-term effective pain management approaches remains a central goal in BMS clinical practice.

The chronicity of pain and the sustained long-term effects of pain interventions have become critical challenges in BMS management. A recent systematic review has suggested that the sustainability of pain reduction or remission in BMS has not been adequately evaluated, probably due to the short follow-up periods—often less than a year—in most studies [10]. Previous studies indicated that complete spontaneous remission was observed in only 3∼5 % of patients within 3∼5 years after the onset of BMS, and <50 % of patients showed improvement in symptoms with treatments [11]. The long wait for spontaneous remission is often unrealistic and can lead to the chronicity of pain, posing a major therapeutic challenge. Current studies provide low-quality evidence for the short-term efficacy of drug therapy (DT), such as clonazepam, alpha-lipoic acid, pregabalin, gabapentin (Neurontin), pramipexole, carbamazepine, amitriptyline, duloxetine, and mecobalamin [12]. Additionally, non-pharmacological management strategies, including physical therapy (e.g., photobiomodulation [PBM] and oral cryotherapy [OCT]) and psychological interventions (e.g., cognitive behavioral therapy), are also included [13,14]. Physical therapy modalities represent essential innovations in pain management, offering the advantages of non-invasiveness, fewer side effects, and good patient tolerance [15]. Our previous clinical trial demonstrated that the combination of PBM and OCT significantly alleviated oral mucosa pain and anxiety symptoms in BMS patients within 7 weeks of intervention [16]. While physical therapy modalities have shown short-term benefits in pain management, their long-term efficacy remains uncertain, particularly given the chronic nature of pain in BMS patients.

Meanwhile, existing studies remain insufficient in investigating the factors contributing to pain recurrence after physical therapy in BMS. Kim et al. [17] identified associations between xerostomia/dysgeusia and symptom recurrence in BMS patients receiving long-term drug therapy (≥3 months; e.g., clonazepam, alpha-lipoic acid, nortriptyline, or gabapentin), suggesting the importance of physiological contributors. In addition, Zhang et al. [18] revealed that psychological factors (e.g., anxiety, depression, and fear of cancer) significantly influence pain prognosis and medication efficacy. However, the long-term efficacy of physical therapy—including temporal patterns of recurrence and maintenance treatment requirements—has not been well explored. To address it, this study aims to quantify pain recurrence and remission patterns under different treatment modalities (PBM, OCT, DT) and investigate the factors contributing to recurrence. We hypothesize that PBM may exhibit sustained long-term efficacy in alleviating pain symptoms in BMS patients, while pain recurrence may be associated with physiological or psychological factors.