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    • Primary stability can be measured by different

    2018-11-12

    Primary stability can be measured by different methods [14]: “biomechanical tests, including na inhibitor and disinsertion torque measurements, and non-invasive techniques such as resonance frequency analysis (RFA)”. RFA offers a clinical measure for implant stability and presumed osseointegration and make it possible to measure implant stability without damaging the bone-implant junction [15]. Most studies have focused on implant stability in augmented posterior regions of maxilla after osseointegration [15,16].
    Patients and methods A preoperative computer tomography scan was used to quantify the amount of available bone at individual implant sites under the maxillary sinus to decide whether the patient could be included in the study. Before the procedure, the anatomy and pathology of the sinuses were evaluated using panaromic view (Fig. 1). The width of the alveolar bone ridges was considered a noninterfering parameter because the width was always sufficient for a secure implantation. According to Cawood-Hawell\'s classification [17], Class V and VI cases were included in the study. Patients who had residual bone height less than 2 mm were excluded. The other exclusion criteria were sinus pathologies, systemic diseases, smoking habits, alcohol consumption and poor oral hygiene. All patients underwent bilateral. Treated lateral window open sinus lifts performed bilaterally on 12 partially or completely edentate patients (8 males and 4 females, aged 49–68 years) with a piezoelectric surgery unit. Patients were treated under local anesthesia using articaine 4% with 1:100,000 epinephrine. After elevation of a full-thickness flap, all cases had their lateral antrostomies created by outlining an island of bone or completely removing the entire lateral aspect of the window using the piezoelectric unit according to the manufacturer\'s instructions. The elevation of the Schneiderian membrane was accomplished by initially exposing and mobilizing the membrane using the piezoelectric hand piece followed by hand instrumentation to further elevate the membrane along the medial wall of the sinus (Fig. 1). A total of 24 sinus lifts were performed and 64 taperd dental implants (Implant Microdent System S.L-Comapedrosa, Barcelona, Spain) measuring 3.4–5.0 mm in width and 12–14 mm in length were placed concurrently with sinus augmentation to achieve primary stability. In all patients, the left side was grafted with DBM putty form (DynaGraft Keystone Dental, Burlington, Massachusetts) and the right side was grafted with DBM powder form (Pacific Coast Tissue Bank, Los Angeles, California) after a minimum of 30 min rehydration process in 0.9% Saline solution. The lateral wall of the sinus was then covered with a membrane (Bio-Gide, Geistlich Pharma AG) (Fig. 2).
    Results Of the 12 patients, 8 (66.6%) were males and 4 (33.3%) were females. The overall age range of the patients was 49–68 years. All implants with upper prosthesis had a 100% survival rate at the point of final observation. All implants osteointegrated successfully in both grafted sides and showed successful results. Six months after surgery, all implants were clinically stable during abutment tightening. Patients\' and interventions\' characteristics are summarized in (Table 1).
    Discussion The sinus lift procedure with bone augmentation is now a well accepted technique for rehabilitation of the posterior atrophic maxilla with implant placement. Simplicity, less invasive, complication-free technique is the most important rules in the success of grafting procedure [20]. Shrinkage and ossification of the blood clot around titanium implants placed in the maxillary sinus and the formation of a new sinus floor have been observed in several studies. Nonetheless, irrespective of the bone-forming site, bone formation and healing require the recruitment, migration and differentiation of osteogenic cells. The lifting of the periosteum may have initiated a resorption process, exposure of the bone marrow and access of stem cells to the sinus cavity, a sequence of events that has been described in animal studies [21,22].