|Tooth impaction refers to the failure of teeth to erupt into the mouth within the normal time, where the failure of outburst appears to originate from mechanical blocking. Tooth impaction may result from a number of local causal factors. These include arch length discrepancy, ectopic positioning of the teeth, presence of supernumerary teeth, mucosal or bony barriers, and retained deciduous teeth.
Scientific journal is a periodical publication intended to further progress of science, usually by reporting novel research. There are thousands of scientific journals in publication, and many more have been published at various points in the past.
Most journals are highly specialized, although some of the oldest journals publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that are peer reviewed, to ensure that articles meet the journal's standards of quality, and scientific validity. The publication of the results of research is an essential part of the scientific method. If they are describing experiments or calculations, they must supply enough details that an independent researcher could repeat the experiment or calculation to verify the results. Each such journal article becomes part of the permanent scientific record.