Introduction:
The skeletal anchorage has extended the envelope of discrepancy in orthodontic treatment by broadening the possible amounts of tooth movement. Because of this increased tooth movement, the consideration of anatomical limits began to be revisited recently using cone-beam computed tomography (CBCT). In addition, the considerable tooth movement over the anatomical limits can raise clinicians' concerns about complications such as gingival recession, bone dehiscence, or root resorption. Therefore, this presentation will discuss the anatomical limits for tooth movements using CBCT, the dentoalveolar changes after substantial tooth movement through the limiting structures, and their long-term retention.

Discussion:
With the advent of the microimplants, as the possible extent of tooth movement has been crucially increased, clinicians now need to consider the related anatomical limitations further. Recently, the anatomical limit can be accurately investigated using CBCT, and the limiting structures would be the anterior palatal/lingual alveolar cortical plate, posterior wall of the maxillary tuberosity, or posterior lingual cortical plate of the mandibular body. In our current series of CBCT research, the palatal or lingual bone was significantly thinned and the root protruding through the cortex was observed along with radiographic bone dehiscence after maxillary incisor retraction (by 8.0 mm) or mandibular molar distalization (by 2.8 mm) with microimplants. Further, the bone loss significantly recovered with newly formed thin bone loss during the retention period (51.28 กพ 21.64 months). Continuous tooth movement with physiologic force and cautious observation of surrounding tissues during treatment might be critical to obtaining favorable bone recovery and minimizing adverse effects.

Conclusions:
Considerable tooth movement using microimplants can significantly decrease palatal/lingual alveolar bone thickness and height and lead to radiographic bone dehiscence. These were favorably recovered with newly formed bone during retention.