TENS Device Use for Discomfort Relief During Orthodontic Tooth Movement

The goal of this clinical trial is to learn if Transcutaneous Electric Nerve Stimulation (TENS) device works to reduce discomfort during orthodontic treatment, by using orthodontic separators to mimic the discomfort of braces. The main questions it aims to answer are: * Does TENS device lower the participants level of discomfort? * Will TENS device be effective with orthodontic tooth movement? Researchers will place the separators on different sides of upper and lower first molars. TENS device will be applied on each participant on one of both teeth (according to their group), so that the results can be compared within the same person. Participants will: * Visit the clinic after 12 or 24 hours (depends on their group) * Stay on dental chair while TENS device is applied. * Rate the discomfort level on VAS scale before and after TENS device application.

Inclusion Criteria: * Full permanent dentition excluding third molars. * Sound not carious nor endodontic treated contralateral first molars. * Interproximal contact mesial and distal to first molar present on both upper and lower molars. Exclusion Criteria: * Dental pain. * Heart arrhythmias. * History of seizures. * Taking any pain medication during the test period. * Missing tooth excluding third molars. * Endodontic treated or carious first molar. * Spacing mesial or distal to the first molar.