Alveolar ridge preservation with a xenograft and a collagen matrix or a free connective tissue graft versus spontaneous healing: A 1-year prospective randomized clinical trial.

Replacement of a single tooth in the esthetic zone is a demanding procedure. The application of a biomaterial in the extraction socket, covered with a collagen matrix or a soft tissue graft may lead to less vertical and horizontal changes of the alveolar ridge and soft-tissues and thereby simplifying the procedure with more predictable outcomes.



The study is a prospective randomized clinical trial with 1-year follow-up. Patients in need for an implant-supported dental crown to replace a maxillary tooth in the esthetic zone are randomized in one of three techniques: A) bone substitute material and a collagen matrix B) bone substitute material covered with a palatal graft, or C) spontaneous healing. After extraction of the tooth, patients will be treated according to their assigned protocol. After 8 weeks a Straumann implant will be placed. The implants are loaded after a minimum healing time of approximately 8-10 weeks. Esthetic and clinical parameters and patient satisfaction is assessed after tooth extraction, before implant placement and up to one year after crown placement. Esthetic scores consist of the Peri-implant esthetic score (PES) and the White esthetic score (WES). Labial soft tissue volume is assessed using digitized casts; the buccal bone is assessed using Cone Beam CT scans. Other assessments are the buccal marginal gingiva, marginal bone level (MBL), plaque index (PI), the bleeding index BI, the gingiva index (GI), the pocket probing depth (PPD) and the width of the attached mucosa (WAM). A patient’s questionnaire includes a visual analog scales (VAS) that will focus on expectation and satisfaction of the surgical procedure and about the esthetic result of the dental crown and the peri-implant tissue.

Alveolar ridge preservation with a xenograftand a collagen matrix or a free connective tissue graft, compared to spontaneous healing, leads to better soft tissue and bone volume for early implant placement and a better aesthetic result, up to 1 year after functional loading.

Pre-operative, one week post extraction, implant placement, 2 weeks after implant placement 1, 6 and > 12 months after placement of the crown.

Group A) Placement of a bone substitute material (deproteinized bovine bone mineral with 10% collagen; Bio-Oss Collagen®, Geistlich) covered with a collagen matrix (Geistlich Mucograft® Seal).

Group B) Placement of a bone substitute material (deproteinized bovine bone mineral with 10% collagen; Bio-Oss Collagen®, Geistlich) covered with a punch biopsy of the palate.

Group C) Spontaneous healing (control group).