from tkinter import as tk
from tkinter import filedialog

class SampleApp(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.container = tk.Frame(self)
        self.container.pack(side="top", fill="both", expand=True)
        self._frame = PageFour(master=self.container, controller=self)

    def switch_frame(self, frame_class):
        new_frame = frame_class(master=self.container, controller=self)
        self._frame.destroy()
        self._frame = new_frame

root = Tk()
root.geometry('600x600')

theLabel = Label(root, text='Deseja iniciar o Ciclo de Cura do Autoclave?')
theLabel.pack()

x1 = Button(root)
photo = PhotoImage(file=u'C:\Users\Tiago\Desktop\Dudu\Pics\green1.gif')
x1.config(image=photo, width='400', height='400', activebackground='black', bg='black', bd=0,
          command=lambda: controller.switch_frame(PageFive))
x1.pack()

x2 = Button(root)
photo = PhotoImage(file=u'C:\Users\Tiago\Desktop\Dudu\Pics\red.gif')
x2.config(image=photo, width='400', height='400', activebackground='black', bg='black', bd=0)
x2.pack()

class PageFive(tk.Frame):
    def __init__(self, master, controller):
        tk.Frame.__init__(self, master)
        self.controller = controller

        page_2_label = tk.Label(self, text="Página 5")
        page_2_label.pack(side="top", fill="x", pady=10)
        self.pack()


if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

root.mainloop()