Dental-implant-supported reconstructions provide comfort and improvements in prosthetic function, adaptation, and stability over conventional treatment options. The objective of this study was to evaluate the effect of different denture cleansing solutions and their influence on the deterioration and loss of retention of overdenture attachments in a 12-month clinical-use simulation. In this way, ten specimens each of different brands of retentive caps made of Teflon (OT Equator[®] (Rhein83, Bologna, Italy), Locator[®] (Zest Anchors, Escondido, CA, USA), Kerator[®] (KJ Meditech, Gwangiu, Republic of Korea), and Locator R-Tx[®] (Zest Anchors, Escondido, CA, USA)) were immersed in five different cleaning solutions (Kukident[®] (P&G Tech, Oxford Parkway, UK), Benfix[®] (Laboratorios URGO S.L., Guipúzcoa, Spain), Corega[®] (Stafford Miller, Waterford, Ireland), and Protefix[®] (Neuhofer Weiche, Parchim, Germany)), and tap water was used as the control group, in a simulation that lasted 12 months. Data were analyzed using two-way ANOVA and a Tukey HSD. Furthermore, a Levene Test and Shapiro-Wilk tests were performed to assess the validation of the ANOVA assumptions. The statistical analysis was performed using R version 4.2.2 software with the significance level set to p < 0.05. There were significant statistical differences between the different manufacturers regarding the retention forces of the attachment's retentive caps (F = 322.066, p < 0.001). For the cleaning solution groups, different statistical results between Kukident[®] (P&G Tech, Oxford Parkway, UK) (p < 0.05) and Benfix[®] (Laboratorios URGO S.L., Guipúzcoa, Spain) (p < 0.05) were observed. There were no significant statistical differences between Corega[®] (Stafford Miller, Ireland), Protefix[®] (Neuhofer Weiche, Parchim, Germany), and tap water, even though the retention forces decreased in all of them.