Will a machine that takes dental x-rays break down after charging it for a long time?

No. A machine for dental films will go into trickle charge mode when fully charged, a long trickle charge will not cause damage to the machine itself, but overcharging can have some potential effects on the charger or battery. A dental film machine is a dental device, also known as an oral CT, which is a device that digitally generates three-dimensional images of the teeth and mouth.