Craniofacial sutures: Morphology, growth, and in vivo masticatory strains

The growth and morphology of craniofacial sutures are thought to reflect th eir functional environment. However, little is known about in vivo sutural mechanics. The present study investigates the strains experienced by the in ternasal, nasofrontal, and anterior interfrontal sutures during masticatory activity in 4-6-month-old miniature swine (Sus scrofa). Measurements of th e bony/fibrous arrangements and growth rates of these sutures were then exa mined in the context of their mechanical environment. Large tensile strains were measured in the interfrontal suture (1,036 mu epsilon +/- 400 SD), wh ereas the posterior internasal suture was under moderate compression (-440 mu epsilon +/- 238) and the nasofrontal suture experienced large compressio n (-1,583 mu epsilon +/- 506). Sutural interdigitation was associated with compressive strain. The collagen fibers of the internasal and interfrontal sutures were clearly arranged to resist compression and tension, respective ly, whereas those of the nasofrontal suture could not be readily characteri zed as either compression or tension resisting. The average linear rate of growth over a 1-week period at the nasofrontal suture (133.8 mu m, +/- 50.9 S.D) was significantly greater than that of both the internasal and interf rontal sutures (39.2 mu m +/- 11.4 and 65.5 mu m +/- 14.0, respectively). H istological observations suggest that the nasofrontal suture contains chond roid tissue, which may explain the unexpected combination of high compressi ve loading and rapid growth in this suture. (C) 1999 Wiley-Liss, Inc.