Pain and Safety of Microneedles in Oral Cavity

A randomized, crossover, double-blind, placebo-controlled, one-session clinical trial with 30 male volunteers was performed to access pain and safety of microneedle topical application in different regions of the oral cavity.

A randomized, crossover, double-blind, placebo-controlled, one-session clinical trial with 30 male volunteers was performed by applying a microneedle patch in the following regions of the oral cavity: lip (inner lower), buccal (cheek: 1 cm behind the month angle), tongue (dorsal surface), hard palate (anterior region), and attached gingiva (between central and lateral upper incisors). A 30 gauge hypodermic needle and an identical patch but without microneedles sticking out, were used as positive and negative controls, respectively. The application force was standardized to 10N by an applicator composed of a 5 mL syringe and a spring. Insertions were performed with a gap of 30 seconds. Pain and discomfort associated to the procedure was evaluated with a Visual Analogue Scale (VAS), by a blinded-dentist. The safety associated to microneedle application was verified immediately after the application (0h) and after the next day (24h). The different application sites were inspected visually for bleeding, ulceration, bruising, redness or swelling.

Application of microneedle patch, 30G hypodermic needle (positive control) and flat patch (negative control) in the lip, buccal, tongue, palatal and gingival mucosa for pain and safety assessment

A microneedle patch (no drug) was applied in the following oral cavity sites: lip, buccal, tongue, palatal and gingival mucosa to access pain, discomfort and safety.

30 gauge hypodermic needle was inserted in the following oral cavity sites: lip, buccal, tongue, palatal and gingival mucosa.

A flat patch was applied in the following oral cavity sites: lip, buccal, tongue, palatal and gingival mucosa.

Pain sensitivity assessment by Visual Analogue Scale after microneedle application in the oral cavity

Pain was evaluated after microneedles, hypodermic needle or negative control topical application application in different oral cavity sites

Number of participants with treatment-related adverse events as assessed by visual inspection of ecchymosis, ulceration, redness, swelling or bleeding after microneedles use in the oral cavity

Any sign of ecchymosis, ulceration, redness, swelling or bleeding right after and 24 h later applications of the devices in different oral cavity sites

Mucosal perforation after microneedles application was confirmed by applying gentian violet to stain the sites of microneedle insertion

Inclusion Criteria: - Healthy male Exclusion Criteria: - Volunteers were free from cardiac, hepatic, renal, pulmonary, neurological, gastrointestinal and haematological diseases, psychiatric disorders, smokers or alcoholic.