Studies utilizing clinical or cast model measurements have shown that the reduction in ridge dimensions is three-dimensional, but it is greater along the buccal surface than along the lingual or palatal surfaces. Changes in bone height are usually moderate. For example, Schropp and colleagues observed that, after 12 months of healing, the height of the buccal bone plate was 1.2 mm apical to its lingual or palatal counterpart. On the contrary, the width of the alveolar ridge in single-rooted teeth will be decreased approximately by 50%, and two-thirds of this reduction will occur within the first 3 months after tooth extraction.