title: Role of basic biological sciences in clinical orthodontics: a case series.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Orthodontics, Case Western Reserve University, Cleveland, Ohio, USA. zdavidovitch@yahoo.com
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Davidovitch
authors.forename: Vinod
authors.initials: V
authors.lastname: Krishnan
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000150:complications; D001690:Biological Science Disciplines; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D005260:Female; D050031:Hashimoto Disease / Q000150:complications; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D007037:Hypothyroidism / Q000150:complications; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008312:Malocclusion, Angle Class II / Q000628:therapy; D024343:Open Bite / Q000628:therapy; D009970:Orthodontics; D010347:Patient Care Planning; D012008:Recurrence; D012307:Risk Factors; D012391:Root Resorption / Q000209:etiology*; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000009:adverse effects* / Q000295:instrumentation; D016312:Treatment Refusal