The aim of the present prospective randomized controlled study is to compare the clinical, radiological, micro-circulation, and histology of a novel, semi-thick, and conventional full-thickness mucoperiosteal flap technique during horizontal alveolar ridge augmentation.

The aim of our study was to compare the clinical, radiological, circulatory, and histological studies of a novel, split-thickness and conventional full-thickness mucoperiosteal flap technique during horizontal alveolar ridge augmentation surgeries. Flap formation was performed in the test group using the novel split-thickness surgical technique, and in the control group using the full-thickness mucoperostatial surgical technique. The novel split-thickness flap technique to be studied results in a predictable, closed healing based on our preliminary results, thus ensuring the conditions for successful augmentation. We primarily want to investigate what hard and soft tissue changes result from ridge augmentation with a novel split-thickness flap technique after 6 months, compared to a surgical technique based on full thick flap formation accepted as a standard procedure in the literature. Our secondary examination methods: examination of early wound healing and micro-circulation after augmentation interventions by LSCI method; histological evaluation at prosthetically designed implant positions.

Inclusion Criteria:

• at least one edentulous maxillary/mandibulary premolar or molar site with horizontal bone loss
• full- mouth plaque and bleeding scores (FMPS and FMBS) <20%
• good patient compliance (including willingness to participate in the follow-up procedures) signed informed consent-

Exclusion Criteria:

• Active infectious diseases (HBV, HCV, HIV, TB, SARS CoV-2, etc.)
• Current chemotherapy or radiotherapy
• Radiation treatment of the former head and neck region (not older than 2 years)
• Untreated insulin-dependent diabetes mellitus
• Clinically significant osteoporosis or other systemic disease affecting bone metabolism
• Clinically significant circulatory disorders such as decompensated cardiac failure
• Haemodynamically significant heart failure or myocardial infarction within the last 3 months
• Clinically significant coagulation disorder
• Current or previous systemic corticosteroid therapy (not older than 2 months)
• Current or previous systemic bisphosphonate therapy
• Pregnant or breastfeeding mothers
• Smoking
• Drug addiction, alcoholism

Participants are not aware of the randomly assigned flap design. Independent examiners are not aware of patient allocation during analysis of clinical and radiographic data.