I have noted that clinical instructors at IKO’s student clinic at the University in Tromsø (now called “The Arctic University of Norway”) do not pay too much attention to occlusion and occlusal discrepancies in students’ patients. The reason for that is not really clear to me. Trauma from occlusion does not only affect periodontal tissues but can have deleterious effects on the pulp-dentin complex, the occlusal surfaces of the teeth (usually aggravating the problem with time), the temporomandibular joints and the neuromuscular system. In my lectures I can only address periodontal problems, which had long been considered minor, based on animal experiments. Recent retrospective studies in humans, however, have told us different lessons. In order to get what you should get after non-surgical and surgical periodontal treatment, it may be justified to better remove any balancing contacts and harmonize working side contacts (apart from establishing proper oral hygiene). It is interesting to remember that, without hard evidence, many dentists’s observations, i.e. clinical experience, has suggested that for almost a century. Excesses by so-called gnathologists exempted.
Since the advent of evidence-based medicine in Dentistry about 20 years ago, we know that animal experiments do not provide hard evidence. They may be used in order to formulate a hypothesis which has to be tested in randomized clinical trials in humans. Moreover, if one has a close look again at the mechanical apparatuses which had been installed in beagle dogs in Gothenburg, Sweden, in the 1970s and 1980s in order to simulate occlusal trauma (a supracontact in an artificial crown on a upper premolar which leads to a violent forward-push of a lower premolar whenever the dog closes its mouth, while a lingual bar with a spring wire attached to that particular lower premolar which pulls back the tooth whenever it opens), one instantly doubts whether this actually fits the purpose. In addition, a dog tormented in that way may experience tremendous stress, may even lose any hope and just want to die. This kind of distress has been shown in the meantime to be an important risk factor for periodontal disease in itself. So, claims by the research group in Gothenburg, that all other factors were controlled for while only dental plaque and occlusal forces combined had an influence on the integrity of periodontal tissues may seriously be questioned.