An infraoccluded ankylosed premolar will generally cause a midline shift toward which side?

When an ankylosed premolar becomes infraoccluded, it means that the tooth has fused with the surrounding alveolar bone and is unable to erupt normally. This condition often results in a loss of vertical dimension for the affected tooth, leading to changes in the occlusion and overall bite relationship.

As the ankylosed premolar remains below the adjacent teeth, it creates an imbalance in the dental arch. The upper teeth typically continue to develop and erupt normally, while the affected tooth does not rise to maintain the proper occlusal relationships. This leads to a shift in the midline of the dental arch toward the affected side because the neighboring teeth will start to drift toward the infraoccluded tooth. The shifting occurs as a compensatory mechanism to maintain function and occlusion, resulting in a noticeable shift toward the side of the ankylosed tooth.

This shift is significant, impacting both aesthetics and function, and may require orthodontic intervention to correct the alignment and overall dental arch relationship.