Alveolar ridge preservation (ARP) reduces dimensional changes following tooth extraction. We evaluated the changes in alveolar ridge dimensions after ARP using bone substitutes and collagen membranes. Objectives included the tomographic evaluation of sites prior to extraction and six months after ARP and the assessment of the extent ARP preserved the ridge and reduced the need for additional augmentation at the time of implant placement. A total of 12 participants who underwent ARP in the Postgraduate Periodontics Clinic (Faculty of Dentistry) were included. Cone beam computed tomography images were used to retrospectively assess 17 sites prior to and six months after dental extraction. Alveolar ridge changes were recorded and analysed using reproducible reference points. The alveolar ridge height was measured at buccal and palatal/lingual aspects, whilst width was measured at crestal level, 2 mm, 4 mm and 6 mm below the crest. Statistically significant changes were found in alveolar ridge width at all four heights, with mean reduction differences ranging from 1.16 mm to 2.84 mm. Likewise, significant changes in the palatal/lingual alveolar ridge height (1.28 mm) were observed. However, changes of 0.79 mm in buccal alveolar ridge height were not significant (p = 0.077). Although ARP reduced dimensional changes following a tooth extraction, some degree of alveolar ridge collapse could not be avoided. The amount of resorption on the buccal aspect of the ridge was less compared to the palatal/lingual after ARP. This indicated that the use of bone substitutes and collagen membranes was effective in reducing changes in the buccal alveolar ridge height.