1. A dentist may decide to extract the tooth to prevent recurrent trouble.
2. The security zone was set up to prevent guerrilla infiltrations.
3. Smear Vaseline on to your baby's skin to prevent soreness.
4. The security forces had to intervene to prevent the situation worsening.
5. Police are out in force to prevent a recurrence of the violence.
6. Lemon juice can help to prevent economy-class syndrome by improving blood circulation.