Top 10 Body Parts That Can Be Successfully Rebuilt

Even the youngest schoolchildren in the United States know about George Washington's wooden teeth, so it's probably not a surprise to learn that teeth can be rebuilt and replaced. We've come a long way since the days of Washington, though, and now damaged or decayed teeth can be replaced with natural-looking implants, bridges and dentures. Researchers are also hard at work finding a way to rebuild teeth before they fully decay. Filling a cavity is just like patching a hole, but these researchers envision that one day, dentists will be able to insert a solution of chemicals that will cause the tooth to regenerate. Remineralized dentin and enamel will take the place of those gold or ceramic fillings, and your tooth would be good as new.

Hip replacements can relieve the terrible pain caused by arthritis. The surgery involves removing diseased bone and cartilage from the hip, and then placing a prosthetic socket and ball that recreates movement in the hip. Some prostheses have a surface coating so that the remaining bone can grow into the implant. Rebuilding the hip wasn't always so easy, though. Early attempts to fashion a prosthesis involved pig bladders, gold and glass, but these materials proved too weak or incompatible with the body.

British surgeon John Charnley is credited with developing the techniques and materials used in the first effective total hip replacement surgery in the late 1950s and early 1960s. His techniques were considered crazy by his peers, but Charnley persevered in his research with polyethylene prostheses. His methods would revolutionize the field of hip replacement, and they also had an impact on this list's next item.

The first knee replacement was performed in 1968. As with hip replacements, the earliest attempts to rebuild the knee were crude and unsuccessful. At one point, artificial knees were just hinges, but the work of John Charnley and others has led to more elegant replacements. Today, recipients of knee replacements can choose a model that is suited for their gender, age, weight and activity level.

In the future, though, joints like the hip and the knee may be able to rebuild themselves. In July 2010, researchers announced they'd rebuilt a rabbit's joint with stem cells. These researchers inserted scaffolding into the rabbit's thigh, and material on the scaffolding stimulated cell growth. The rabbit regained the ability to move and bear weight on the joint. This finding could have an immense impact on the aging human population, as joint replacement surgery becomes increasingly likely the older a person gets. This won't be the last time stem cells come up in this list -- joint regeneration is but one way that these cells may be able to rebuild our bodies in the future.

Leaving an abusive situation is one of the hardest things a person may have to do. It can be immensely difficult to truly leave the past behind, though, when you see the proof of it in the mirror. That's why many plastic surgeons offer to rebuild the faces of domestic violence victims for free. Dr. Andrew Jacono, of New York, is one of those physicians. He became aware of the problem when he performed a reconstructive rhinoplasty for a woman he thought had been in a car accident. When she returned a month later, he learned that her injuries came at the hands of her husband [source: Foster]. He began working with Face to Face, which links abuse victims to plastic surgeons willing to help for free. These plastic surgeons see injuries like knife wounds, cigarette burns and crushed cartilage, but they rebuild the face so that survivors can close that sad chapter of their lives.

Soldiers earn our respect for their work on the battlefield, but they often receive nothing but uncomfortable stares when they return. Researchers have been developing new ways to rebuild the body parts that soldiers might lose in combat. Prosthetic ears are particularly cool and useful to soldiers. To make the new ear, lab technicians take 3-D scans of the patient's head and match the model to the other remaining ear. If a patient lost both ears, technicians can use images of a family member's ear; one patient at Lackland Air Force Base's facial prosthetics lab requested his father's ears, which were recreated with the exception of wrinkles so they'd be age-appropriate [source: Roberts]. The new ears match the patient's skin tone perfectly and also feature approximations of veins and sun exposure.

A mastectomy, or the removal of one or both breasts, is a common treatment for breast cancer. Women who undergo the procedure often worry about how they'll look afterward, and breast reconstruction can provide immense psychological benefit and restore confidence to these women. There are several methods for rebuilding the breast. Doctors can use implants or the patient's own tissue to rebuild the breast so that it matches the other one; if both breasts were removed, doctors can use photographs to replicate what the woman had to begin with. Some mastectomies don't require the removal of the nipple, but if the nipple is removed, doctors can replace this as well. They'll use a small flap of tissue to rebuild the nipple, and then they rely on medical tattooing to shade the nipple and the areola.

Until just a few years ago, a severe burn was the equivalent of a death sentence. Doctors must excise the burnt skin quickly to save the patient, but they must cover the wound with something quickly; without their skin, burn victims are in constant pain and at risk for dehydration, shock and infection. In 1980, researchers Ioannis Yannas and John F. Burke published a paper about a synthetic skin membrane that could be applied to such injuries. This skin layer, made from shark and cow collagen, can serve as scaffolding while new skin cells grow. But the question of where to get these new skin cells was another problem. Doctors tried using skin from the patient's family members or from cadavers, but now it's possible to build new skin from the patient's own skin cells. Doctors can biopsy a few cells and send them to a lab where the cells divide and divide until there's an entire sheet of skin. Another source of rebuilt skin? Infant foreskins, which can grow hundreds of times their original size in the laboratory.

Heart disease is the leading cause of death in the developed world, so the race to find ways to rebuild a damaged heart is intense. Stem cells may provide a way to fix this vital organ, and though these methods aren't available yet, we'd like to provide a sneak peek at some of the coolest research being conducted.

Tubular scaffolding, which scientists can build in the lab, is at the core of attempts to rebuild a heart. Ideally, this scaffolding would be implanted into the human heart and serve as the model for new cell growth. Stem cells, when placed on the scaffold, could yield new blood vessels, which would reduce the need for harvesting new vessels from the patient. The scaffold could also help new heart tissue to grow, which could be key to repairing damage after a heart attack. In one study, researchers used the scaffolding to grow new heart muscle cells, which were successfully implanted into rats.

In 2008, scientists in Barcelona announced that they'd transplanted the first tissue-engineered trachea into a 30-year-old woman. The woman, who'd suffered a severe case of tuberculosis, was admitted to the hospital because of shortness of breath that left her unable to care for her children. Doctors decided to replace her trachea with one they grew in the lab using the woman's own stem cells. They used a trachea that had been donated by a man who died of a cerebral hemorrhage. All existing cells were taken off the donor trachea, and then the patient's own stem cells were placed onto it. Because the woman's own stem cells were used, there was a lesser chance that her body would reject the trachea, which is one of the most common reasons for transplant failure. Only four days after the operation to place the new trachea, it was nearly impossible to tell the transplant from the existing lung system. And just two months after the operation, tests of the woman's lung function showed that she was in the normal range for someone her age.

The bladder holds the distinction of being the first complex human organ to be rebuilt in a laboratory and placed in human patients. The patients' own cells were used to build the bladders. These cells were harvested during an operation to remove bladder damage and then placed on scaffolding that shaped the growing cells. The new bladders were ready in seven weeks, and in 1999, doctors performed the first operation to sew the new bladder to the existing one. The researchers performed seven such surgeries and followed the patients for a minimum of two years before announcing their success. This advancement holds tremendous promise for replacement organs. So many people die each year waiting for a transplant, but now it may be possible to harvest organs for those people before time runs out.