Immediate Loading and immediate restoration with CAD/CAM prosthesis
Francisco Teixeira Barbosa

  1. Factors related with primary stability

     

    Primary stability, as a definition, is a mechanical connection between the implant and the bone, and there isn’t any biological adhesion between them. It is important to note that primary stability might be affected by several factors (Touati and Guez, 2002) such as: bone availability, objective evaluation of primary stability, implant design, surgical protocol.

     

  2. Bone availability and quality

     

    The bone availability and quality may vary depending on the location (maxilla or jaw), age and gender, so that it is well known the different kinds of bone, both qualitatively and quantitatively (Brånemark, Zarb, and Albrektsson 1985). It can be expected a bone type I or II at the jaw, being the maxilla more variable, being common the types III and IV.

     

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    picture 1.1 Lekholm e Zarb Classification.png

  3. Objective evaluation of primary stability

     

    The measurement of primary stability after implant placement may be done through resonance frequency analysis (RFA) with an Osstell®, which values can variate between 0 and 100 and its reference unit is the ISQ (Implant Stability Quotient) index.
     
    There is no consensus about using the Osstell® as a reliable tool relating the values obtained and the true biological behavior of the implant (Huwiler et al. 2007; Nkenke et al. 2003; Schliephake, Sewing, and Aref 2006; Ito et al. 2007; Abrahamsson, Linder, and Lang 2009), since neither histomorphometric nor clinical studies weren’t able to conclude a strong enough correlation between ISQ index and the %BIC (Bone-to-Implant Contact). 
     
    There are clinical studies that found correlation between bone density and the ISQ values obtained (Boronat-López et al. 2006; Ostman et al. 2006; Alsaadi et al. 2007). Another thing to note is the bone remodulation rate observed in implants where an elevated insertion torque was applied and those where a threading tap was used, being higher the bone remodeling rate on those implants where the press fit is augmented, despite this study had been performed on mandibular labrador dog. 
     
    As clinical utility of the Osstell® it can be established the following scale (Sennerby and Meredith 2002):
    1. ISQ value < 60 - Not enough primary stability to immediate loading.
    2. ISQ value > 60 - Optimal primary stability to immediate loading.

     

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