This study aims to compare the pain experienced by patients undergoing orthodontic treatment with Invisalign ® corrective aligners with that of patients undergoing orthodontic treatment with conventional braces. Because the aligners are removable, nearly invisible and don't involve metal that can irritate teeth and gums, we are expecting less pain in the Invisalign Treatment and less affectation of the quality of life.

The aims of the study are to determine:

the presence of pain, the magnitude of pain, the duration of pain, and the location of pain.

The hypotheses of this study are:

• Treatment with Invisalign ® aligners result in less pain than the braces
• Treatment with Invisalign ® aligners result in less irritation to the soft tissues with braces
• Pain should increase each time the aligners are put in the mouse and decrease until disappearing on the third day.
• The quality of life will be most affected by treatment with braces than with Invisalign ®.
• Null Hypothesis: There is no difference at all points between the two treatments.

Inclusion Criteria:

• In permanent dentition;
• Age less than 30 years;
• No medical contraindications or presence of systemic diseases (including nervous system disorders);
• No missing teeth except the third molars;
• Orthodontic treatment without extraction.
• Relationship skeletal cl. I (or slightly cl. II or cl. III)
• Speak and understand French without help.

Exclusion Criteria: lack of compliance with appointments.

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Patients are recruited from the Department of Orthodontics at the University of Montreal.