Role of basic biological sciences in clinical orthodontics: a case series.

INTRODUCTION: Orthodontic therapy is based on interaction between mechanics and biology. Basic biologic research aims at developing a better understanding of the mechanism of transformation of mechanical energy into biologic reactions, and exposing the reasons for iatrogenic tissue damage in orthodontics. Previous research has shown that inflammation is a major part of the biologic response to orthodontic forces. In inflammation, signal molecules that originate in remote diseased organs can reach strained paradental tissues and exacerbate the inflammatory process, leading to tissue damage. METHODS: Our case series includes 3 patients, each having had systemic diseases and malocclusion. One had diabetes mellitus, Hashimoto's thyroiditis, and depression. Concern about the possible effect of these conditions on the well-being of the teeth and their surrounding tissues compelled the orthodontist to choose not to treat this patient. The other 2 patients had allergies, and 1 also had bronchial asthma and bruises. RESULTS: Although these conditions are thought to be risk factors for root resorption, these patients received orthodontic treatment for 2 and 3.5 years, respectively. At the end of treatment, both had excessive root resorption of many teeth. In 1 patient, this damage led to the loss of most maxillary teeth. CONCLUSIONS: Basic research should continue to address questions related to the biologic mechanisms of tooth movement on tissue, cellular, and molecular levels. Moreover, this research should continue to identify risk factors that might jeopardize the longevity of treated teeth. Such basic research should promote the development of new tissue-friendly and patient-friendly therapeutic methods.

TMJ osteoarthritis/osteoarthrosis and immune system factors in a Japanese sample.

OBJECTIVE: To determine whether there is an association between temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA) and immune system factors in a Japanese sample. MATERIALS AND METHODS: The records of 41 subjects (7 men, aged 22.0 +/- 3.8 years; 34 women, aged 24.8 +/- 6.3 years) and 41 pair-matched controls (7 men, aged 22.1 +/- 2.3 years; 34 women, aged 24.8 +/- 6.4 years) based on age and gender were reviewed. Information on medical history included local or systemic diseases, details on medication type and use, and the presence of allergies and asthma. Dental history questions referred to details regarding past oral injuries. The validity of the hypothesis, defining allergies and asthma as risk factors in OA, was tested by using a logistic regression analysis. RESULTS: The incidence of allergy was significantly higher in the TMJ OA (P = .008), with a mean odds ratio of 4.125 and a 95% confidence interval of 1.446-11.769. CONCLUSION: These results suggest that allergy may be a risk factor in association with TMJ OA in this Japanese sample.

Adverse effects of orthodontics: a report of 2 cases.

Adverse effects are results beyond the expected good outcomes of treatment. Like any other field in dentistry and medicine, orthodontics is not immune to such effects. The probability of adverse results in orthodontics increases when important rules and facts are ignored. To illustrate this, treatment and its adverse effects in 2 patients are discussed. In 1 young adult female, a palatally impacted maxillary canine was being moved into its place in the arch when it became ankylosed. Despite the cessation of movement, the orthodontist continued to apply mechanical forces to the canine for an additional 16.5 years. The effect of this extremely prolonged treatment period on the rest of the dentition was devastating. In another case, a 12-year 10-month-old boy with a mild Class II, Division 1 malocclusion, developed alopecia areata 4 months after the onset of orthodontic treatment. Four months later, he had lost all of his hair (alopecia totalis). The etiology of this condition was determined to be psychological stress and anxiety evoked by the orthodontic treatment. In both cases, the orthodontists failed to recognize existing problems or chose to ignore them. It was concluded that these adverse effects of orthodontic treatment could have been avoided if the orthodontists would have paid closer attention to the tissue response to mechanotherapy, as well as to the patient's attitude toward treatment. The latter conclusion is particularly noticeable when treating children and teenagers, who can reject being forced by their parents to undergo orthodontic treatment.

Cellular, molecular, and tissue-level reactions to orthodontic force.

Remodeling changes in paradental tissues are considered essential in effecting orthodontic tooth movement. The force-induced tissue strain produces local alterations in vascularity, as well as cellular and extracellular matrix reorganization, leading to the synthesis and release of various neurotransmitters, cytokines, growth factors, colony-stimulating factors, and metabolites of arachidonic acid. Recent research in the biological basis of tooth movement has provided detailed insight into molecular, cellular, and tissue-level reactions to orthodontic forces. Although many studies have been reported in the orthodontic and related scientific literature, a concise convergence of all data is still lacking. Such an amalgamation of the rapidly accumulating scientific information should help orthodontic clinicians and educators understand the biological processes that underlie the phenomenon of tooth movement with mechanics (removable, fixed, or functional appliances). This review aims to achieve this goal and is organized to include all major findings from the beginning of research in the biology of tooth movement. It highlights recent developments in cellular, molecular, tissue, and genetic reactions in response to orthodontic force application. It reviews briefly the processes of bone, periodontal ligament, and gingival remodeling in response to orthodontic force. This review also provides insight into the biological background of various deleterious effects of orthodontic forces.