Signaling molecules and genetic mechanisms involved in orthodontic tooth movement

The objective of this review is to highlight recent developments in cellular, molecular, tissue, and genetic reactions in response to orthodontic force application. Histologic, histochemical, and immunohistochemical studies in the 20th century and the early 21st century demonstrated that many phenomena, both physical and biologic, are involved in tooth movement. When mechanical forces are applied, cells, as well as the extracellular matrix [ECM] of the [periodontal ligament] PDL and alveolar bone, respond concomitantly, resulting in tissue remodeling. During the early phases of orthodontic tooth movement, PDL fluids are shifted, and cells and ECM are strained. In areas where tension or compression evolves under the influence of the orthodontic appliance, vasoactive neurotransmitters are released from distorted nerve terminals. In the PDL, most terminals are near blood-vessel walls. Therefore, the released neurotransmitters interact first with capillary endothelial cells. In response, the endothelial cells express receptors that bind circulating leukocytes, promoting their migration by diapedesis out of the capillaries. These migratory cells secrete many signal molecules, including cytokines and growth factors, some of which might be categorized as inflammatory mediators, that stimulate PDL and alveolar bone lining cells to remodel their ECM. This force-induced remodeling facilitates movement of teeth to areas in which bone had been resorbed

Role of malocclusion in tension type headache

The purpose of this study was to clarify the role of occlusal traits in recurrent tension-type headache without signs or symptoms of temporomadibular disorders in adolescents to facilitate more evidence-based therapies in the treatment of tension-type headache. This cross sectional study was carried out on a total of 600 adolescents from Jan 2007 to Oct 2010 at Prince Rashid bin Al Hasan Hospital, Irbid province of Jordan. A complete headache group of 25 adolescents were recruited in this study. A control group of 25 adolescents was obtained, equally matched to the headache group for gender and closely matched for age and dental classification. The data collection comprised of a structured questionnaire answered by the patients and a subjective evaluation about their emotional state. A specific questionnaire for temporomandibular disorders was applied, followed by a clinical examination. Plaster models were made during orthodontic initial records for each patient to obtain certain occlusal traits measurements. On the basis of the results obtained in this study, it was concluded that overbite problem [p=.031], overjet problem [p=.037] and posterior crossbite [p=.047] were displaying statistically significant associations [p<.05] with significantly increased risk [>2.7:1] of tension type-headache