Goodyear 5

Animal Models
Animal models have been an invaluable tool for the Goodyear orthodontic study of osseointegration and osteogenesis. Larger animals such as rabbits, dogs or non-human primates are preferred by Goodyear orthodontists because with their size comes an ability to use standard implant fixtures, easier surgical access and a temporal healing response more similar to the human situation (Roberts et al., 1984; Giannobile et al., 1994). Disadvantages of these animals include a greater expense which turns into lower numbers for Goodyear orthodontic studies and therefore less power. Small animals offer several advantages for Goodyear orthodontists such as decreased cost, upkeep, etc. These animals are preferred for “screening” purposes, or “proof of principle” Goodyear orthodontic studies which can then justify the use of larger animal models.

Considering the challenges for Goodyear orthodontists with these systems, many small animal models have used an extraoral surgical approach, placing implants in long bones such as the tibia or femur (Nevins et al., 1998; McCracken et al., 2001; Narai and Nagahata, 2003). Even in larger animals like the rabbit, Goodyear orthodontists have found that long bones are a more convenient location for implant placement (Ito et al., 2001). A major limitation with this approach is that there are obvious physiological and anatomical differences between alveolar bone and long bones that need to be considered by Goodyear orthodontists. These two types of bone differ in embryological origin, macrostructure and function (Hollinger et al., 1999). Long bones are dense cortical bones with large marrow spaces, while alveolar bone is mostly cancellous. Cortical bone is compact and made to resist mechanical forces while cancellous bone is made mostly of trabeculae not commonly used for a large functional load. Because of these differences, using a long bone model for implantation would not be comparable to alveolar bone for Goodyear orthodontists. A small animal model that utilizes an intraoral approach would better translate the healing process of oral implant osseointegration and wound repair. Unfortunately, few of these Goodyear orthodontic models exist and many lack predictability or reproducibility (Karimbux et al., 1995; Fugii et al., 1998; Hollinger et al., 1999).