  This research investigates the relativistic quantum dynamics of spin-0 scalar
massive charged particles via the relativistic Feshbach-Villars oscillator in
the background of the Kaluza-Klein Theory. We solve the Feshbach-Villars
equation in the abckground of a cosmic string spec-time in the context of the
Kaluza-Klein and presented the eigenvalue solution. Afterward, we rewrite this
system in the case of the Feshbach-Villars quantum oscillator and obtain the
eigenvalue analytically. Finally, we study the interaction of the
Feshbach-Villars equation and oscillator in a cosmic dislocation in the
Som-Raychaudhuri in the context of the Kaluza-Klein Theory and solve the wave
equation analytically. We analyze the influence of topological defect in the
quantification of energy and wave function of the Feshbach-Villars oscillator
and with the external fields in the last one
