Sutures and forces: A review

Department of Pediatric Dentistry
Lutheran Medical Center

Resident’s Name: Craig Elice Date: 10/2/2009
Article title: Sutures and forces: A review
Author(s): Wagemans P, van de Veide, et al.
Journal: Am J Orthod Dentofac Orthop
Volume (number): 94:129-41, 1988
Major topic: Sutures and forces, basic science
Type of Article: Review article
Main Purpose: This paper describes the biology behind sutures, and its response to extrinsic mechanical forces
Sutural Growth and its regulation: Most facial and cranial bone are of intramembranous origin and grow by apposition and resorption at the periosteum interface and by sutural growth. Theories exist to suggest that these growth centers are autonomous or affected by environmental extrinsic forces. Sicher is most famous for his view that sutures have intrinsic growth potential and uses epiphyseal plates as an example. Moss believes that sutures adapt to surrounding structures and forces A growing brain acts as a functional matrix to determine skeletal and sutural growth. Van Limborgh concurs that growth is controlled by few intrinsic genetic factors and many local nongenetic factors that originalte in adjacent structures of the head and neck. These latter theories are consistent with current thought.
Sutural Morphology: Generally, sutures are composed of several layers of cells which respond to external stimuli. A consensus among studies is that a suture is composed of osteocytic and fibrocytic cells, fibers, and blood vessels. The organization of these layers is still controversial as histologic animal studies show conflicting results. The morphology of the sutures is also influenced by age as the sutures becomore more complex with age and eventually the opposing bony edges can fuse. Biochemical analysis of the sutures indicate that a number of substances are detected in suture development. These substances include Type III and V collagen, geleatin, fibronectin and certain small proteoglycans. All of them play a role in sutural development, however it is unknown what specific role they play.
Translation and transduction of forces : It is difficult to quantify these forces because forces can not be isolated to a specific area without being connected to the surrounding tissues. When rapid palatal expansion was evaluated, force levels before and after sutural opening were similar most likely because when the suture opened, forces were still be absorbed by surrounding craniofacial complex thus interfering with the ability to measure the forces in an isolated area like the palatal suture. Studies also looked at the conversion of mechanical forces to cellular activity. It is thought that the mechanical energy is converted into electrical energy (Piezoelectricity). The effects of external mechanical forces was studied and it was proposed that the sutural response can be divided into several stages. Initially,, a traumatic response is noted where there is cellular death and resorption, followed by connective tissue repair. New bone is deposited in perpendicular or parallel to the areas of the suture in tension areas and resorption takes place in areas of compression. The long term effects appear to show some relapse either from elastic recoil of the tissues, or an imbalance with the surrounding tissues.
Conclusions: Research is being conducted to understand the effects of external forces on sutural growth and development. It is now understood that response of sutures to mechanical forces is determined by the duration and direction of the forces, morphology of the suture, and the age of the patient. However, it is unknown if all sutures react in a comparable manner to a given force or if sutures react differently to different magnitudes of force. The author suggests that the development of a good in vitro model that would accurately predict responses in vivo.
Assessment of article: Very complex article which was difficult to read and understand.