First premolars substituting for maxillary canines—Esthetic, periodontal and functional considerations
There are clinical situations in orthodontics when the treatment results show that the maxillary first premolars have been moved to the position normally occupied by the canines. This may be the case, for example, (1) when space closure is selected as the treatment alternative for missing lateral incisors; (2) in some cases with severely displaced impacted canines, which are extracted rather than orthodontically corrected; and (3) in some transposition situations.
Since the clinical crown length of premolars generally is much shorter than that of the canines, substituting maxillary first premolars for canines may create an esthetic problem, particularly in unilateral cases, This may be a problem particularly in persons with a high lip line, who display much gingival tissue when smiling. Furthermore, the differences in number of roots and in root morphology between maxillary first premolars and canines might be a reason for long-term periodontal and functional problems. What is the currently available evidence-based research and clinical information in these areas?
—Nejat Erverdi, Istanbul, Turkey