The present study aimed to evaluate clinical and radiographic outcomes of sticky bone in comparison to crosslinked hyaluronic acid mixed with xenograft in alveolar ridge preservation.

After teeth extraction, the alveolar process goes through a remodeling process that leads to dimensional changes that end up with a decrease in the width and height of the alveolar bone; these changes happening after tooth loss proves that the alveolar process bone is tooth dependent.

Alveolar bone remodeling is a physiological process observed after tooth extraction that may compromise the subsequent dental implant rehabilitation. Most of the alveolar bone loss occurs during the first 3-6 months after tooth extraction, resulting in a bone width loss of 29-63%, which leads to difficulties restoring the teeth either with conventional prosthesis or with implant supported prosthesis and in many cases implant placement becomes a challenge.

To compensate for this alveolar remodeling and create an aesthetically implantsupported prosthesis, many bone grafting techniques were proposed, including guided bone regeneration, onlay bone block, and alveolar ridge preservation.

The latter is a prophylactic technique that involves inserting various biomaterials into the socket to reduce post-extraction changes. The two most commonly used bone grafting materials are allografts and xenografts. The Alveolar ridge preservation seeks to achieve successful ridge reconstruction, which involves the production of new bone within the volume of the old socket. Although xenografts provide steady and adequate bone volume maintenance, their healing time and the percentage of de novo bone production remain their main downside.

To improve alveolar ridge preservation outcomes, researchers are attempting to reduce the healing period so that implants can be placed shortly after tooth extraction. As a result, numerous growth factors were investigated as biological adjuvants to aid in the healing process and prevent physiological post-extractive bone loss. Recent researches studied the use of cross-linked hyaluronic acid (xHyA) gel as a biological adjuvant to xenograft in order to increase regeneration capacity and decrease post-extraction resorption Hyaluronic acid an extracellular polymer of disaccharides administration appears to have a beneficial impact on the healing process and bone cell response by stimulating mesenchymal cells proliferation, growth factors attraction and angiogenesis in situ. the cross-linked hyaluronic acid had been introduced with a slow degradation profile to maintain a longer presence. The combination of crosslinked hyaluronic acid mixed with xenograft was proved to be better than the xenograft only regarding post-extraction socket bone regeneration "Sticky bone" is a composite biomaterial designed for bone regeneration, combining particulate bone substitutes with autologous platelet aggregates, such as PRF and concentrated growth factors. This adaptable material conforms to various bony defects, preventing graft movement and preserving bone volume during healing, thus minimizing the need for block bone and titanium mesh.

The sticky bone had been used in socket preservation and provides good bone quality for further implant placement. The placement of sticky bone resulted in grafted material adherence to the recipient sites without micro and macro movements, and the PRF matrix prevented early epithelial ingross onto the defect site, resulting in significant new bone gain in both horizontal and vertical dimensions Sareen et al. reported in their systematic review that a major limitation was the lack of randomized controlled trials that provide evidence on alveolar ridge preservation with sticky bone. They recommend larger studies to evaluate the interest of sticky bone in various surgical procedures by comparing it with other existing materials and conventional techniques.

The present study aimed to evaluate clinical and radiographic outcomes of sticky bone in comparison to crosslinked hyaluronic acid mixed with xenograft in alveolar ridge preservation.

Inclusion Criteria:

• Age >18 years old.
• Patient with hopeless maxillary anteriors and premolar with cl ii socket that needs extraction and delayed implant placement.

Exclusion Criteria:

• Acute abscesses or active infections localized in the proximity of the surgical field.
• Presence of heavy metallic artefacts that can distort CBCT scans
• Bad oral hygiene and non-compliance.
• Systemic diseases interfering with bone healing.
• Active and progressive periodontal disease
• Smoking, alcoholism and drug abuse
• Pregnant and lactating women