Background: Placement of oral implants is frequently compromised due to atrophy of the alveolar process. Lateral ridge augmentation with an autogenous bone block is frequently necessary to increase the width of the alveolar process before implant installation. However, harvesting of an autogenous bone block is associated with donor site morbidity. Consequently, bone substitutes alone or in combination with particulate autogenous bone graft are used increasingly to simplify the surgical procedure. Animal and human studies evaluating lateral ridge augmentation with Bio-Oss alone or in combination with particulate autogenous bone graft have demonstrated new bone formation and high implant survival. However, the optimal ratio of Bio-Oss and particulate autogenous bone graft for lateral ridge augmentation and long-term implant survival is unknown.

Purpose: Test the H0-hypothesis of no difference in long-term implant survival, newly formed bone, volumetric stability of the graft, gained width of the alveolar process and patient satisfaction after lateral ridge augmentation with Bio-Oss alone or in combination with a diminutive amount of autogenous bone graft.

Material and methods: lateral ridge augmentation will be performed in 20 adults with two different ratios of Bio-Oss and autogenous bone graft after a split mouth design. Clinical and radiological measurements will evaluate the long-term implant survival. Cone beam computer tomography (CBCT) will be obtained preoperatively, immediately postoperatively, prior to implant placement, 2 years after implant installation and 5 years after implant installation to estimate the volumetric changes of the augmented area. Moreover, the amount of newly formed bone will be estimated by histologic evaluation after implant placement.

Conclusion: Long-term implant survival has never been evaluated after lateral ridge augmentation with Bio-Oss alone or in combination with a diminutive amount of autogenous bone graft.

Inclusion Criteria:

• Total or partial bilateral edentulism
• Horizontal bone width less than 4 mm at planned sites of implant installation or need of augmentation of aesthetic reasons for optimal implant placement

Exclusion Criteria:

• Uncontrolled systematic disease
• History of radiation in the area
• Smoking habits (free of smoking habits more than 1 month prior to treatment)
• Treatment with bisphosphonates
• Patients who cannot complete the 5-year observation period