الفهرس 
Introduction .Only 14 pages are availabe for public view
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Abstract
Ridge resorption resulting from tooth loss often compromises ideal implant placement. Hence, in these situations, bone augmentation is often recommended to provide the required ridge width and height. Different techniques have been described for bone grafting: bone block and/or guided bone regeneration (GBR) are used for horizontal bone augmentation, with good predictability and satisfactory final outcomes (McAllister and Haghighat, 2007). However, autogenous block graft remains one of the main methods for reconstructing atrophic resorbed maxilla (Jensen and Terheyden., 2009; Miron et al., 2011; Monje et al., 2014). Among the complication associated with bone augmentations is soft tissue dehiscence, which is the primary cause for bone graft exposures (Lundgren et al., 2008). As a negative consequence, such complication can lead to partial or complete loss of the bone graft (Lundgren et al., 2008).
To guarantee a successful final outcome of any surgical procedure, a tension-free primary closure of the soft tissues is important to preserve the vascularisation of the tissues (Cordaro et al., 2002) and to reduce the risk for subsequent post-surgical infections (Wang and Boyapati, 2006). In an attempt to achieve a complete and tension-free primary soft tissue closure over the grafted area, flap advancement is usually performed by mobilizing the mucoperiosteal flap by deep periosteal releasing incisions. However, it compromises the integrity of the periosteum overlying the bone graft, which results in diminished blood supply to the bone graft, less new bone formation and poor bone remodeling activity (Zhang et al., 2008; Abrahamsson et al., 2010).
Thus, Soft tissue expanders have been introduced in implant surgery, as pre-augmentation devices, to avoid the complications associated with bone-grafting procedures. The concept of soft tissue expansion is based on the biological properties of various soft tissues, such as skin or mucous membranes, to react to applied mechanical forces by true tissue growth (cell proliferation) (Neumann, 1957; Kaner and Friedmann, 2011; Mertens et al., 2015). Soft tissue expanders have the ability to enlarge soft tissue volumes without altering its thicknesses and to generate tissues with appropriate color match and texture similar to that of the original tissues (Fang et al., 2013).
The aim of the present study was to evaluate the effectiveness of a sub-periosteal osmotic soft tissue expander prior to horizontal ridge augmentation. And evaluation of alveolar bone width after ridge augmentation The Results obtained from this study suggest that soft tissue expansion by self-inflating osmotic expander is a predictable approach for gaining a surplus amount of soft tissue before alveolar ridge augmentation.
16 patients were selected, All patients have partially edentulous ridge (missing upper one or two neighboring anterior teeth or premolars) of the maxilla. The edentulous area was required horizontal bone augmentation procedures owing to lack of sufficient residual bone and insufficient soft tissue Class IV ridge defect according to Benic and Hammerel classification.
Results showed that Soft tissue expander successfully provides a Surplus amount of soft tissues in 5 out of 8 patients. hence, STE is a predictable approach for gaining a sufficient amount of soft tissue before alveolar ridge augmentation. The mean and standard deviation values for soft tissue volume gain were 393.9 (322) mm3 in all cases. Regarding radiographic percentage changes in bone width in both groups, there was no statistically significant difference between percentage increases in bone width in the two groups after six months. as group I and group II revealed 58.8 % and 77.1%, respectively. Regarding histomorphometric analysis for new bone formation, our result in group I showed statistically significantly higher mean bone surface area than control Group.