Which of the following is a preventive orthodontic measure?

The selection of proper use of space maintainers in the primary dentition as a preventive orthodontic measure underscores the importance of maintaining space in the dental arch for the permanent teeth. Space maintainers are devices designed to hold the space left by a prematurely lost primary tooth until the permanent tooth is ready to erupt. The early loss of primary teeth can lead to neighboring teeth drifting into the empty space, which can result in misalignments and crowding when permanent teeth begin to erupt. By effectively using space maintainers, the likelihood of orthodontic issues in the future can be significantly reduced, promoting a more favorable alignment of the permanent dentition.

In contrast, the other options do not primarily serve as preventive orthodontic measures. The placement of fixed bridges is more restorative and addresses function and aesthetics rather than preventing future orthodontic problems. Sound restorative dentistry to retain primary teeth is important but does not directly prevent orthodontic issues as space loss can still occur if primary teeth are lost before the proper time. Extraction of unerupted teeth typically addresses existing space problems or issues but does not prevent future orthodontic complications. Therefore, the focus on utilizing space maintainers effectively highlights its role in preventing potential alignment issues in forthcoming permanent dentition.