Describing the process to the "Daily Mail" Professor Jake Barralet from McGill University said, "The 'paper' in our printer is a thin bed of cement-like powder. The inkjet sprays the cement with an acid which reacts with it and goes hard. That deals with one layer. Then new layers of fresh powder are sprayed on top and the layers build up to the shape we need" [Daily Mail].
The entire process takes only 10 minutes to print most grafts. What further differentiates this method from other types of grafts and artificial inserts is that the compounds in the printer contain the same building blocks found in human bones. The grafts can also eventually dissolve into the human body, allowing natural bone to take its place.
The printer's sophisticated design means that precise "holes" can be left in the graft to encourage the body's own tissue to regrow and rejuvenate the area. This ability allows very specific grafts to be made for sensitive areas or for bones to grow in a specific manner to affect tissue repair, which can also be useful in reconstructive surgery where a doctor is trying to allow an area to both heal and maintain a certain appearance.
Professor Barralet says that inkjet-produced bone grafts are "a long way" from being used in hospitals, but the project appears to have tremendous potential.
Professor Barralet's team is not the only group employing inkjet technology to develop new bone graft techniques. A company called Advance Ceramics Research Inc., in Tucson, Arizona, has developed a technology called "Plasti-Bone." Like inkjet-produced bones, Plasti-Bone is strong enough to act as a graft but also porous to encourage bone regeneration and allow blood to flow through the bone. Plasti-Bone is made from a biologically friendly plastic with a ceramic coating, and natural bone begins bonding to Plasti-Bone after about eight weeks. The artificial bone eventually dissolves harmlessly into the body.
In order to create their Plasti-Bones, ACR designs them on computers and then produces them through rapid prototyping fabrication. Rapid prototyping builds layer upon layer, similar to inkjet technology, and allows scientists to control how long the bone remains in the body before dissolving by altering porosity and the thickness of the ceramic coating.
Like the technology being developed at McGill University, Plasti-Bone will likely be first used in place of small, natural bone grafts and it will be years before entire bones are replaced through this process.