Mucocele is a relatively common oral lesion that presents as a painless, dome-shaped, translucent swelling containing sticky mucin [1]. The main causes include trauma and chronic irritation, and they commonly occur on the lips, floor of the mouth, and tongue [2]. Regarding the site distribution of oral mucoceles, the lower lip is most frequently affected (59.6%), followed by the floor of mouth (21.2%) and tongue (15.4%) [3]. While the cause is clearly identified in most cases, some cases present with unclear etiology. Particularly, mucoceles occurring in the retromolar area or soft palate are relatively rare and may lead to delayed diagnosis [4,5].

This case report describes a 68-year-old male who presented with a painless mass on the lingual side of the left second molar retromolar area for one month, accompanied by gastrointestinal symptoms including dyspepsia and esophagitis of unknown origin. Careful history taking revealed that mouth taping used to prevent mouth breathing during sleep was the cause of the mucocele. As this represents an extremely rare cause that has not been previously reported in the literature, this report presents the clinical characteristics and course of this unusual case.

This study was approved by the Institutional Review Board of Dankook University Dental Hospital (DKUDH IRB 2024-11-004), and the committee waived the requirement for written informed consent.

A 68-year-old male visited our hospital with a chief complaint of a mass-like lesion that had developed on the lingual side of the left mandibular second molar area one month prior (Figure 1). Along with the lesion, the patient experienced symptoms of dyspepsia and esophagitis, but had delayed seeking treatment due to the absence of significant pain, only visiting after noticing an increase in the lesion’s size.

Figure 1. Initial presentation of the lesion on the lingual side of the left mandibular second molar area.

Despite receiving a week of antibiotic and ointment treatment at a local dental clinic, the symptoms did not improve, and multiple areas of induration were noted upon palpation. The patient reported no unusual findings in this area during a dental examination two months prior.

Oral examination revealed a lesion located on the lingual side of the left mandibular second molar area, covered with overlying mucosa and showing induration upon palpation. The lesion was minimally painful to touch. After one week, an additional lesion developed on the buccal mucosa adjacent to the left mandibular premolar area. Following the occurrence of the additional lesion, an environmental factor interview was conducted. The patient had been using oral breathing prevention tape EasySOOM (SPOL Co., Ltd., Korea) during sleep, but had recently switched to Mouth Seal (Doyen, China). Given the suspected association between the lesions and mouth taping, the patient was advised to discontinue its use immediately (Figure 2).

Figure 2. Clinical appearance of the lesion after discontinuing mouth taping.

Panoramic radiographs and previous medical records showed no significant findings in the area. Visual examination revealed a white protruding lesion suggesting a mucocele, but due to its atypical location and induration, additional examination was deemed necessary for definitive diagnosis.

Regarding systemic symptoms, the patient underwent endoscopy and abdominal CT scan to investigate weight loss, but no significant findings were observed. The patient’s appetite subsequently improved, and weight gradually increased.

After discontinuing mouth taping, the lesion appeared to improve initially, but continued to recur in smaller sizes at 2-week intervals. Therefore, surgical excision was performed and the specimen was sent for histopathological examination, which confirmed the diagnosis of mucocele, suggesting that the use of mouth tape may have been the direct cause of the lesion. After surgical excision, no recurrence was observed during the follow-up period (Figure 3).

Figure 3. Final follow-up showing improvement of the lesion.

Mucocele is a common benign lesion in the oral cavity, typically associated with mechanical trauma. It most commonly occurs on the lower lip and usually presents as a solitary lesion with a low recurrence rate. This case report of multiple mucoceles caused by mouth taping has several clinical implications.

First, the mucoceles in this case developed at atypical locations - the lingual and buccal aspects of the molar area - rather than the typical lower lip location. This suggests that the adhesive components of externally applied mouth tape can dissolve in saliva and flow into the oral cavity, causing mucosal irritation. Particularly during sleep, the adhesive components may dissolve due to salivary flow and increased body temperature, leading to increased likelihood of oral penetration, and this chemical irritation can potentially cause mucosal lesions.

Second, a temporal relationship was observed between the lesion development and the change in mouth tape products. The occurrence of lesions after switching to a lower-cost alternative product emphasizes the need for serious consideration of product quality, particularly regarding adhesive safety and its potential effects on oral mucosa.

Third, although the lesions initially showed improvement after discontinuing mouth tape use, they continued to recur cyclically at 2-week intervals, albeit in smaller sizes. Surgical excision was required for complete resolution, after which no recurrence was observed. This case demonstrates that while removing the causative factor may reduce the severity, surgical intervention may be necessary for complete resolution of mucoceles.

This case suggests that various types of interactions between chemicals and the oral mucosa can lead to mucocele formation. According to Davis et al. [6], irritant contact stomatitis can present with diverse signs and symptoms depending on the nature, mode of application of the irritant, and individual susceptibility. The oral lesions initially showing improvement after removing the causative agent but recurring in 2-week intervals aligns with known patterns of oral mucosal responses to irritants.

Chi et al.’s [7] large-scale review of 1,824 mucocele cases found that mucoceles rarely occur in the retromolar area (0.5%), making this case’s presentation in the lingual aspect of the molar area particularly noteworthy. Furthermore, More et al.’s [8] study emphasizes that oral mucoceles predominantly affect younger populations, with maximum prevalence in the second decade of life, making this case in a 68-year-old patient unusual both in terms of age and location.

The recurrent nature of the lesions despite removal of the apparent cause (mouth tape) suggests a complex interaction between mechanical trauma and chemical irritation, potentially involving the mechanisms described by Davis et al. [6] regarding the pathogenesis of chemical and mechanical irritation in oral tissues.

Therefore, when encountering mucoceles in atypical locations, dentists should conduct careful history-taking regarding patients’ habits and products used, particularly focusing on oral adhesive products such as mouth tape. Furthermore, if conservative management is chosen after removing the causative factor, regular follow-up is necessary as these lesions may show a pattern of recurrence. In this case, surgical excision proved to be an effective definitive treatment.

This case represents the first report demonstrating that commonly used mouth tape can cause mucoceles through the penetration of adhesive components into the oral cavity, providing valuable insights for the diagnosis and treatment of similar cases in the future.

This work was supported by the National Research Foundation of Korea (NRF) grant funded by Priority Research Center Program 2019R1A6A1A11034536.

No potential conflict of interest relevant to this article was reported.