Sinuses are cavities inside the structure of our skull. When we lose a tooth, the bone around the root area starts to recede. This can lead to the sinus expanding into the tooth root area. If you choose to have an Implant … … there may not be sufficient bone to support it. Special material can be inserted to encourage bone re-growth and ‘lift’ the sinus. Over time, the bone will re-grow … … providing enough bone to support the Implant.