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Editor’s Note:  Grant has been away playing in Glacier National Park, and Jason is away in Colorado taking part in the grueling Transrockies Run.  While we’re away, we thought we’d post an article Grant (along with friend and colleague Dr. Steve Hendry) wrote a couple of years ago for the Science Based Medicine Blog.  It’s just as relevant to the mission and purpose of The Prism as it is to SBM, so we thought it would be fitting to reprint it here.  This version has been slightly modified from the original.

Form follows function, as the old saying goes. Nowhere in the human body is this adage more fitting than in the oral cavity.  In less than two generations, the practice of dentistry has evolved from basic pain relief and function-based procedures (such as extractions and fillings), into today’s practices of complex cosmetic rehabilitation, orthopedic and orthodontic management of the teeth, jaws, and facial structures, replacing missing teeth with dental implants, and treatment of sleep apnea and temporomandibular joint (TMJ) disorders, to name but a few.   With such rapid progress, it is to be expected that for every science based advance made in our field, there are just as many claims that are either dubious in their evidential support or outright pseudo-scientific or anti-scientific nonsense.

In this article, we’ll be taking a look at the roles that health care practitioners such as chiropractors, osteopathic physicians, and physical therapists, are attempting to play in the dental field.  We will also see how well-meaning dentists have been trained in and apply their pseudo-scientific principles in their dental practices. In particular, we’ll be examining Cranial Osteopathy (also known as Craniosacral Therapy or Cranial Therapy) in the management of the dental patient, the purported benefits claimed by practitioners of cranial osteopathy, and the quality and quantity of evidence for this type of treatment in the scientific literature.

Basic Skull Anatomy

The human skull is made up of some eight cranial (head) bones and fourteen facial bones.  These bones help protect the organs of vision, hearing, taste, equilibrium, and smell. Without them, our brains would continuously spill out onto the table, which would be embarrassing and maladaptive.  They also provide attachment for muscles that move the head, control facial expressions and chew our food.  At birth, the spaces between the cranial bones- called fontanelles – are relatively wide and elastic, allowing the infant to squeeze through the birth canal and later permitting brain growth in the first few years of life.  In humans the lateral fontanelles close soon after birth, the posterior fontanelle generally closes several months later, and the anterior fontanelle may remain open for three years.

By early childhood, the cranial bones become tightly interlocked in a zig-zag, zipper like pattern (illustrated nicely here) that renders them immovable in a macroscopic sense, although each suture (called a synarthrosis if you want to impress your friends at parties) has a very slight amount of flexibility- 10-30 micrometers on average (1 micrometer = 1/1000th of a millimeter or approximately 4/100,000ths of an inch).  These sutures fill the minuscule space between the cranial bones, essentially stitching them together with dense, strong connective tissue fibers called Sharpey’s fibers.

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