Even after atraumatic tooth removal and/or immediate implant placement, some reduction of the alveolar ridge dimension is expected. To counteract (or limit) this reduction, alveolar ridge preservation technique (ARP) was developed. However, standard ARP techniques, such as grafting with bone substitutes, have some concerns, such as a long healing time prior to implant installation, residual graft particles, and often the need of re-grafting at implant installation. To overcome some of these limitations biologics have been discussed as an alternative approach, such as cross-linked hyaluronic acid (xHyA). However, whether the use of biologics only can achieve comparable results to the standard techniques, has yet to be answered.

The aim of the present single-blind, randomized controlled clinical trial is to test non-inferiority in terms of mid-buccal alveolar ridge height resorption 4 months after ARP between 1) control/standard treatment (i.e., grafting with bone substitutes and socket seal) and 2) test treatment (i.e., xHyA applied with a collagen sponge and socket seal) at maxillary non-molar teeth.

Forty-eight patients will be included and randomly assigned to one of the following 2 groups: 1) control group: standard ARP with deproteinized bovine bone material and covering of the socket with a free gingival graft (FGG) (n=24), 2) test group: application of xHyA soaked in a collagen sponge and covered by a FGG (n=24). The primary outcome parameter is the extent of mid-buccal alveolar ridge height resorption after 4 months, i.e., prior to implant installation, and the sample size calculation is based on a non-inferiority limit of 0.6 mm. The secondary outcome parameters are frequency of additional grafting at implant installation due to 1) a bony dehiscence or fenestration, 2) a thin buccal bone (< 1.5 mm), or 3) contour improvement, cervical alveolar ridge width, alveolar ridge volume, histomorphometric assessment of alveolar ridge healing, feasibility of implant installation, aesthetic outcome parameters, patient reported outcome measures, changes in keratinized mucosa width, soft tissue healing, and assessment of postoperative complications. Patients will be followed up to 1 year after prosthetic restoration.

Inclusion Criteria:

(1) Patients elder than 18 years in need of (2) maxillary non-molar tooth extraction, and (3) later rehabilitation with delayed implant installation.

Exclusion Criteria:

(1) Patients with chronic diseases (e.g., uncontrolled diabetes mellitus, etc.) and/or (2) taking any medication, influencing hard or soft-tissue healing; (3) acute pain/infection or (4) presence of a fistula at the extraction site; (5) untreated periodontal disease; (6) >25% of the buccal bone plate missing after tooth extraction; (7) pregnancy; (8) history of hypersensitivity or allergy to xHyA or xenogenic bone substitute material; and (9) inability to attend the follow-up appointments.