American Board of Orthodontics (ABO) Practice Exam

To determine the space gain from the exfoliation of primary teeth c (central incisor), d (lateral incisor), and e (canine) to their permanent successors, it is essential to understand the typical width of primary teeth compared to their permanent counterparts.

Primary teeth are generally smaller than permanent teeth, leading to an increase in arch length and overall space when the primary teeth are replaced by their successors. The average sizes of the primary teeth in question, combined with the expected dimensions of the corresponding permanent teeth, provide a basis for calculating the space gain.

Research indicates that the difference in mesiodistal width from the primary to permanent dentition for these specific teeth tends to culminate in a space gain that aligns with the reported figures. In the case of primary teeth c, d, and e, their replacement by the permanent dentition typically results in a total space gain around 4.8 mm. This value is derived from clinical studies that average the mesiodistal widths of both primary and permanent teeth adequately.

Utilizing established orthodontic norms for tooth development and eruption patterns ultimately leads to the conclusion that the space gain from the exfoliation of teeth c, d, and e to their permanent successors is accurately represented as 4