Bone width is critical for successful implant placement, as thin bone increases the risk of bone loss. Various augmentation techniques-especially guided bone regeneration (GBR)-are effective in restoring bone volume using grafts and barrier membranes. Collagen membranes are commonly used but degrade quickly, leading to the development of improved types like porcine peritoneum membranes, which show better strength and durability. While autogenous grafts are the gold standard, combining different graft materials (e.g., xenograft and allograft) has shown promising results. However, no studies have directly compared porcine peritoneum membranes with cross-linked membranes using such graft combinations. This study aims to evaluate and compare their effectiveness in increasing bone width.

Bone width is of major importance for implant placement, particularly in ensuring the long-term success and stability of the implant. Implants placed in the presence of thin buccal bone width are significantly more prone to exhibit major dimensional changes and vestibular bone loss (1,2). Various lateral bone augmentation techniques, such as guided bone regeneration, ridge expansion, distraction osteogenesis, and block grafting, have consistently demonstrated efficacy in restoring alveolar ridge dimensions(3). Additionally, the application of different types of graft materials-autogenous, xenogeneic, and allogenic-has been extensively documented in the literature for use in the lateral approach, further enhancing the success of these procedures(4).

Guided bone regeneration (GBR) has become a widely accepted and studied clinical method for the management of horizontal ridge deficiency . It is a biological technique designed to facilitate bone regeneration by creating a space that employs bone grafts and barrier membranes during the surgical procedure(5). Various types of barrier membranes are available for GBR, broadly categorized into non-resorbable and resorbable types. Non-resorbable membranes, like those made from polytetrafluoroethylene (PTFE), require a second surgical procedure for removal, while resorbable membranes, such as collagen-based membranes, can be left in place as they are integrated and eventually absorbed by the body(6). Among the various materials tested for use as regenerative tissue barriers, collagen has emerged as an optimal choice, meeting many necessary criteria(7,8). However, a significant limitation is the challenge of sustaining its barrier function for an adequate duration, typically lasting only four weeks due to the rapid biodegradation caused by the enzymatic activity of host tissues and microorganisms. To address this issue, various physical, chemical, and enzymatic cross-linking methods have been developed to prolong the degradation rate of collagen membranes. Consequently, there is a broad array of collagen types available, each differing based on its extraction source, offering versatility for various clinical applications(9). A recent advancement in collagen membranes is the introduction of the porcine peritoneum collagen membrane, a natural, non-cross-linked material. Studies have demonstrated its biocompatibility and effectiveness as a membrane for bone regeneration including GBR procedures(10-12). Research on porcine peritoneum shows it contains significantly more elastic fibers than pericardium , leading to two to three times greater maximum load and burst pressure. Additionally, it demonstrates superior in vitro resistance to enzymatic degradation, indicating enhanced durability and suitability for biomedical applications(11).

As previously discussed, various bone types can be utilized in guided bone regeneration (GBR). Autogenous grafts are considered the "gold standard" in bone grafting due to their unique combination of osteogenic, osteoinductive, and osteoconductive properties(13-15). However, their limited availability , patient's morbidity , fast resorption rate and the potential for complications at the donor site necessitate the exploration of alternative graft materials(16). Additionally , studies have shown that combining autogenous bone with xenogenic materials in different proportions demonstrated successful tissue integration for the implants, high survival rates and low complication rates (17-20) . Although the bone substitutes has been widely used , the mixture between allogeneic -xenogeneic has been rarely documented until recently . In fact , these studies confirmed the effectiveness of using this combination in guided bone regeneration surgeries, highlighting their synergistic potential in enhancing bone regeneration outcomes(21-28). Furthermore, a study from the Periodontology Department at Saint Joseph University of Beirut on lateral ridge augmentation, utilizing a xenogeneic-allogeneic graft mixture with two different membrane types, has been submitted for publication.

To date, there are no clinical studies comparing the use of non-cross-linked porcine peritoneum collagen membranes with cross-linked bovine-derived membranes in conjunction with a combination of allograft and xenograft materials for guided bone regeneration. This lack of direct comparative research highlights the need for further investigation to assess their relative efficacy and clinical outcomes in regenerative procedures.

This clinical trial aims to evaluate the effectiveness of a porcine peritoneum membrane compared to a cross-linked membrane in guided bone regeneration (GBR) for lateral ridge augmentation. Both membranes will be tested using the same bone graft material, with outcomes measured by assessing volumetric changes in bone width.

Inclusion Criteria:

• - Patients aged 20 to 75 years.
• Healthy individuals, either non-smokers or smokers consuming fewer than 10 cigarettes per day.
• Full mouth bleeding score (FmBS) below 20%.
• Full mouth plaque score (FmPS) below 15%.
• Presence of a residual alveolar ridge with a bone width of less than 6 mm but sufficient bone height in the maxilla or mandible.
• Tooth extraction must have been performed at least six weeks prior to surgery.
• Adequate number of teeth to allow for the use of an occlusal stent or radiographic guide.

Exclusion Criteria:

• - Presence of systemic illnesses.
• Smoking more than 10 cigarettes per day.
• Underwent radiotherapy in the head or neck region within the past 5 years.
• Active periodontitis affecting the remaining teeth.
• Pregnancy.
• Use of medications that could impact bone turnover or mucosal healing, such as tetracycline in the last month, steroids within the past 6 months, bisphosphonates, therapeutic doses of fluorides, or vitamin D and its metabolites within the last 6 months.