Toothbrushes are generally sold according to three leverls of bristly stiffness. " hard medium and soft."
Everyone has own preference but my dentist always recomnend the patient choosing the "soft" toothbrush and replacing it every three month for do the best job. Hard and medium toothbrush can cause damage of healthy and expediting gum. Make sure you brush your teeth correcetly , hold your toothbrush face to your teeth and rotate your wrist extend at a 45 degree angle , must rinse your mouth after brushing your teeth.