**5. Maxillary sinus augmentation**

*Oral and Maxillofacial Surgery*

%25 (**Figure 7**) [44].

**Figure 7.**

**4. Alveolar ridge splitting**

*Iliac block grafts fixated on the atrophic maxilla.*

greenstick fracture is created [47, 48].

demonstrated at maxillary reconstruciton sites [43]. In a similar study conducted by Vermeeren et al., panoramic x-rays are evaluated for 5 years and resorption rates ranging between %44–50 are observed at sites grafted with block bones. Several studies report variety of resorption rates from %42 to %87 when autogenous block bone grafting is performed. Utilizing a collagen membrane along with autogenous block bone grafting is demonstrated to reduce resorption rates up to

Alveolar ridge split is a common technique used in the presence of horizontally deficient alveolar ridges. Surgical procedure for this technique is initiated by one horizontal crestal osteotomy [45]. Piezosurgery, oscillating saws or diamond burs and chisels can be used for the initial osteotomy [2]. Different chisels of increasing width progressively create a gap between the buccal and palatinal/lingual plates afterwards. Interpositional grafting and/or immediate implant placement is oftenly applied to the created gap. This concept is based on the osseous plasticity of trabecular bone. Therefore, a 3- to 5 mm residual crest width is required for the procedure. Fractures may occur in ridges with lower width due to less presence of trabecular bone and less plasticity [46]. To gain greater amounts of new bone, vertical osteotomies may be added to the initial horizontal osteotomy. Another surgical concept of ridge splitting is the displacement of buccal plate by adding a second horizontal osteotomy apically to the initial horizontal osteotomy. In this concept, greenstick outfracture from the basal bone is created on purpose. If full-thickness flap is elevated, the plate should be fixed with screws to the palatinal/lingual plate. Partial-thickness flap is also preferred to keep periosteal vascularization when

This procedure is indicated in cases presenting 3 to 5 mm bone width, with sufficient trabecular bone under the cortical layer. Two-stage ridge split is found to have high success rates up to %97 in terms of implant survival. Studies report 3 to 3.5 mm mean horizontal bone gain with this procedure [48]. Still, there are some drawbacks of this procedure: unpredictable results in severely atrophic crest where

**154**

Maxillary sinus is one of the paranasal sinuses, located adjacent to posterior maxilla. It's an air-filled anatomical cavity, lined with a membrane called "Schneiderian Membrane". Bone resorption following tooth loss, in conjunction with maxillary sinus pneumatization, causes crestal atrophy in the maxillary posterior region. Maxillary sinus floor elevation provides enough bone height for implant placement in atrophic posterior maxilla. To elevate the Schneiderian Membrane, various techniques are developed. These techniques are classified in two main categories: lateral window approach and transalveolar approach.
