https://www.canada.ca/en/department-national-defence/corporate/policies-standards/medical-standards-military-occupations/dental-enrolment-standards.html
Chapter 5 - Dental Enrolment Standards and Dental Condition on Enrolment
5. The following conditions may result in rejection of an applicant or deferral of enrolment until the condition is corrected:
a. an unrepaired cleft lip and/or palate;
b. acute or chronic temporomandibular joint dysfunction and severe limitations of jaw opening which require immediate treatment and/or continual follow-up treatment;
c. a malignant lesion that requires long term therapy; and
d. abnormal maxillofacial skeletal relationship which compromises functional ability and interferes with the ability to perform military duties, for example the inability to wear a respirator or retain a diving regulator.
6. The following conditions will result in deferral of enrolment until the condition is corrected:
a. edentulous with no satisfactory denture replacement;
b. any pathological lesion or condition which could be exacerbated while on normal military duty; and
c. the active phase of orthodontic treatment, if such treatment is required to treat an underlying functional disability/medical condition. If orthodontic treatment is not required to treat an underlying functional disability/medical condition, enrolment may proceed if the applicant signs the Statement of Understanding on orthodontic treatment which is found in the Recruiter's Handbook, Annex D to Chapter 2.