Introduction:
Teeth are extracted for a variety of reasons, including severe decay, endodontic problems, severe periodontal destruction, inadequate residual crown structure, root resorption, iatrogenic factors such as perforations, injuries due to trauma, and cosmetic problems. Aim of the research: To compare different sizes of Iranian bone allograft particles (CenoBone) in preserving grafted socket dimensions.

Material and methods:
It was an experimental study. Twenty healthy patients who had 25 unpreserved single-rooted teeth were included in the study. Patients were randomly divided into two equal groups. In the first group, allograft particles with a size of 150–500 µm and in the second group, particles with a size of 1000–2000 µm were placed in the socket. Then, Iranian resorbable membrane (CenoBone) was placed on the socket openings and buccal wall and was initially closed by a coronalizing buccal flap. Buccal wall height and ridge width in the two groups were compared immediately after surgery and 4 months after surgery with radiological evaluation (cone-beam computed tomography – CBCT) of the region.

Results:
In both groups the horizontal dimension was significantly different after treatment (p < 0.002). In both groups the vertical height was significantly different after treatment (first group: p < 0.001, second group: p < 0.003).

Conclusions:
Use of CenoBone to fill bone socket is essential to preservation alveolar bone dimensions, because use of this material improves soft and hard tissue.