Biology of Tooth Movement.

Research in the field of cellular and molecular biology is relatively lagging in comparison to mechanical advances in the field of orthodontics. Even though the mechanical advances are used quite carefully during orthodontic tooth movement, traumatic effects on the periodontium have not been totally prevented. This may be because of a lack of complete understanding of the cellular complexities. Proper understanding of cellular and molecular biology will help design mechanics that will produce maximum benefits during tooth movement with minimal tissue damage. The rate of tooth movement depends on the rate at which bone remodels and hence, better knowledge of specific biochemical pathways in individual patients will provide a key to predicting how well teeth respond to mechanical forces. This in turn will provide for better tooth movement and faster treatment procedures. The pressure tension theory as well as the bioelectric theory have been discussed in detail along with various chemical mediators with the lipo-oxygensase pathway as well as they cyclooxygenase pathway. Role of neurotransmitters and vasoactive amines along with mechano-transduction has been discussed in the review. These predictors, however, need further work to validate reliability.

Role of Genes in Odontogenesis.

With the discovery of the homeobox genes in craniofacial biology researchers across the globe have studied in depth the genetic patterning of the craniofacial region. With respect to craniofacial development –, Barx, Dlx, Gsc, Lim, Msx, Otx, Prx; part of the Hox cluster are important. Barx gene are strongly expressed only in the mesenchyme of the developing molars. Dlx gene expression is noted in the mandibular and maxillary arch ectomesenchyme. Msx genes are expressed in the area of epithelial mesenchymal interactions in the brachial arches in the area of future dentition and also expressed in the formation of skull, facial primordial and sense organs. Msx-1 is seen to be expressed in various stages of tooth formation i.e bud and cap stage of organogenesis. Lim genes which control morphogenesis of the first brachial arch, are expressed in the maxillo-mandibular ectomesenchyme. Prx gene expression is seen in the proximal portion of the mandibular arch. The role of hox genes in the morphogenesis of the jaws and the dentition is immense. Thus it has been proved beyond doubt that the genes have a major role in organogenesis than what human beings have ever envisaged. This review will give the scientific community an overview of all the genes affecting odontogenesis.