Pain and safety of microneedle application in the oral cavity of human volunteers

Author(s)

Stephany Di Carla

• Document type: Master's Dissertation
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2019-03-25

Examining board members

Michelle Franz Montan; Leonardo Rigoldi Bonjardim; Paulo Henrique Ferreira Caria

• Advisor: Michelle Franz Montan

Abstract

The objective of the present study was to develop and evaluate the feasibility of an applicator device; as well as the intensity of pain and safety due to the application of microneedles (MN) in several regions of the oral cavity. For this, an applicator device was developed composed of a 5 mL syringe and a spring positioned inside. The compression of the spring inside the syringe in 2 mm (n = 10 devices) was performed against an analytical balance (n = 10) to evaluate the kg /F induced by spring deformation on two different days in order to confirm if the device was able to induce a homogeneous application force. Afterwards, the application of MN with the device was performed in the following regions of the oral cavity: gingiva, palatine alveolar process, buccal mucosa, dorsum of the tongue and inner portion of the lower lip. The regions were stained with a solution of gentian violet in order to show the microperforations created, and to confirm if the standardized force was able to perforate the different regions. In a randomized, double-blind, crossover study, 30 volunteers were submitted to topical application of a patch of MN, 30G hypodermic needle (NE, positive control) and an identical patch without MN (FL, negative control) for evaluation of pain arising from applications. The safety of the use of the treatments was evaluated visually immediately after (0 h) and the next day (24 h) of the applications to verify the occurrence of ecchymosis, ulceration, redness, swelling or bleeding. Pain scores were compared by means of analysis of variance (ANOVA) with two criteria, followed by the Tukey test. The level of significance was set at 5%. The evaluated device developed a constant force of application of approximately 10 N, with coefficient of variation of 6.96% and was able to perforate uniformly all the sites of the buccal cavity. In all the evaluated sites, the application of the MN promoted less pain when compared to the NE (p<0.05), but the MN promoted more pain when compared to the FL (p <0.05), except in the tongue, where the MN did not differ from the FL (p> 0.05). In addition, NE promoted more pain when compared to FL in all evaluated sites (p <0.001). There were no cases of bruising, ulceration, redness, or swelling. The MN promoted points of bleeding in the gingiva and in the palatine alveolar process immediately after the application and the NE promoted bleeding in all evaluated sites. There was no case of bleeding in the next day. In conclusion, the developed applicator device allowed the development of a homogenous application force capable of perforating the different sites of the oral cavity in a safe and painless manner when compared to the 30G hypodermic needle, offering a promising way to improve the effectiveness of topical formulations applied to the oral cavity (AU)

• FAPESP's process: 16/24057-0 - Evaluation of pain after topical application of microneedles at the oral cavity of healthy volunteers
• Grantee: Stephany di Carla Santos
• Support Opportunities: Scholarships in Brazil - Master