Estabilidade do pH de soluções anestésicas locais armazenadas em tubetes de polímero sintético e sólido amorfo sob diferentes condições: estudo laboratorial

Abstract

This laboratory experimental study aimed to evaluate the pH variation of the most commonly used local anesthetic solutions in Dentistry, comparing plastic (synthetic polymer) and glass (amorphous solid) cartridges under different storage conditions. The research analyzed the influence of temperature and storage time on the pH stability of 2% lidocaine hydrochloride with 1:100,000 epinephrine, 3% mepivacaine hydrochloride without vasoconstrictor, 2% mepivacaine hydrochloride with 1:100,000 epinephrine, and 3% prilocaine hydrochloride with 0.03 UI/mL felypressin. Measurements were performed using a digital benchtop pH meter, and the data were subjected to statistical analyses, including Shapiro-Wilk, ANOVA, Tukey, and TOST tests to verify equivalence with literature and manufacturer reference limits. The results demonstrated that the 3% mepivacaine hydrochloride without vasoconstrictor solution maintained the highest stability and mean pH values across all evaluated conditions. Regarding the storage method, refrigeration proved to be the most effective environment for pH preservation, while storage in an incubator accelerated the acidification process of the samples. Concerning the packaging material, synthetic polymer cartridges presented slightly higher and more stable pH values in most formulations, except for prilocaine hydrochloride with felypressin, which demonstrated better stability in amorphous solid (glass) cartridges. It is concluded that temperature and cartridge material are determining factors for the chemical integrity of local anesthetics. It is recommended that dental surgeons prioritize refrigerated storage and that the logistics chain improves thermal control to ensure quality and clinical comfort during drug administration.