This invention relates to molds and, more specifically, to an adjustable mold for use in fabricating bone replacements or implants, particularly for the lower jaw (mandible).
For wounds resulting in a tearing away (avulsion) of bony structure, reconstructive surgery, bone implants, and/or grafts are needed to restore bone continuity. Furthermore, the majority of patients who undergo reconstructive facial surgery require partial or complete dentures (dental prostheses). For a dental prosthesis to fit and function properly in the mouth, there must be a successful reconstruction of a bony base ample enough to support the prosthesis.
Current technique for replacing missing mandibular bone involves using a piece of bone taken from another portion of the patient's body. However, replacements for avulsed or excised (resected) segments of the mandibular bone may be possible in the future with synthetic bone implants. Such implants may be made of polymers which are biodegradable, that is, can degrade by biological processes over time as the adjacent bone grows back. As noted above, it is extremely important for successful reconstructive surgery that the geometry of the bone repair material accurately duplicates the lost bone.
Present techniques for fabricating synthetic polymeric bone replacements involve curing them in static, i.e., nonadjustable, mold. However, synthetic bone replacements are needed in many different sizes for use not only in humans but also in laboratory animals since this technology is still primarily experimental. Not only does the use of static molds require that a new mold be constructed each time a new size replacement is required, but, once cured in the mold, replacements frequently stick to the interior surfaces making their removal difficult. Furthermore, these molds, due to their construction, are frequently limited in the methods which can be used to sterilize them.
Adjustable molds do exist, e.g., U.S. Pat. Nos. 3,964,727; 1,323,345; 955,282; and 765,365. However, none exist in the medical field for the purpose of fabricating bone replacements. The cited patents relate to molds for continuous casting of molten steel and for casting concrete and printing type. Obviously, the large size of the molds of the referenced patents, their intended uses, and the lack of ability to sterilize them based on the materials used in their construction would not suggest that they be used or modified to fabricate bone replacements. Furthermore, none of the inventions of the referenced patents employ Applicants' unique design for moving the adjustable portion of the mold and locking it in place.
The use of tetrafluoroethylene polymer in molds also is known. See, e.g., French Patent No. 1,586,203. However, this invention is a static, nonadjustable mold whose ceramic construction would be too brittle to lend itself to bone replacement fabrication.