Abstract
Remodeling is the physiologic term for internal turnover of a mineralized tissue, without a change in its overall form. It is a coupled sequence of catabolic (resorptive) and anabolic (osteogenic) events to support calcium homeostasis and repair (renew) aged or damaged mineralized tissue. Histological studies indicate that both bones and teeth remodel. Remodeling mechanisms are involved in growth, functional loading, tooth movement, root resorption, and the systemic health of patients. Cortical bone remodeling is via cutting/filling cones, also referred to as bone multicellular units (BMUs). Trabecular bone remodeling is accomplished by hemicutting/filling cones (surface resorption cavities that fill with new bone), also termed a bone multicellular unit (BMU). Histologic studies in multiple species have demonstrated that root resorption cavities are usually repaired (filled) with secondary cementum. In effect, this is "remodeling" of the root of a tooth. The evolution of bone remodeling concepts, as originally defined by Harold Frost, are important for understanding craniofacial growth and the skeletal adaptation associated with orthodontics and dentofacial orthopedics.
| Original language | English |
|---|---|
| Pages (from-to) | 216-237 |
| Number of pages | 22 |
| Journal | Seminars in Orthodontics |
| Volume | 12 |
| Issue number | 4 |
| DOIs | |
| State | Published - Dec 2006 |
Bibliographical note
Funding Information:Dentistry was first exposed to Frost’s ideas at the Utah (1956-68) and Sun Valley Workshops (1969-present), organized by Webster S. S. Jee and supported by the National Institute of Dental Research (NIDR) ( The workshops were funded by NIDR to expose dental and graduate students to bone research and hopefully interest them in academic careers in dentistry. The dental training program included summer dental student experiences, as well as predoctoral and postdoctoral tracks leading to a PhD degree. The first bone workshop was in the summer of 1965 at the University of Utah, School of Medicine, in Salt Lake City. An oral pathologist, Murray Bartley ( was the first dentist to complete PhD training at the University of Utah as a NIDR postdoctoral fellow. He entered a full-time academic career at the University of Oregon. The first dental student to be recruited for a postdoctoral fellowship was W. Eugene Roberts (WER) ( Fig 4 ). Figs 4 and 5 ), Figs 4 and 5 ). He graduated with a PhD in anatomy in 1969 and pursued orthodontics specialty training at the University of Connecticut. WER subsequently served as full-time faculty at the University of Pacific and Indiana University, where he is currently the Director of the Graduate Orthodontics Program. Harold Frost was a prominent member of the faculty for the Utah/Sun Valley Workshops from their inception; he had a strong influence on the hundreds of bone workshop participants until his death in 2004.
Funding Information:
The second critical innovation for defining bone physiologic mechanisms was plastic embedding and sectioning of fully mineralized bone. James Schoonover Arnold, MD (1923-2003), a bone pathologist at the University of Utah in the 1950s, developed a method for embedding undemineralized bone in plastic and sectioning them with saws or heavy sledge microtomes. Dr. Arnold ( utilized a variation of the methacrylate technology previously developed in dentistry for fabricating custom oral prostheses. Following the introduction of atomic weapons in the World War II, there was great interest in studying the pathophysiology of bone seeking radioisotopes (plutonium, thorium, strontium, and so on), the highly toxic byproducts of the atomic age. Because of the difficulty associated with studying hard tissue histology, it was necessary to develop techniques to embed and section bones without removing the mineral component, because the latter contained the radioisotopes of interest. The principal funding for Dr. Arnold’s research was provided by the United States Atomic Energy Commission (AEC). A parallel line of AEC funding investigated the effects of ionizing radiation on DNA of cells within or near bone. The latter eventually evolved into the Human Genome Project. Fig 16 )
ASJC Scopus subject areas
- Orthodontics