Development & Eruption Of Teeth — Basic Theories
By: Dominic Thorncroft
Tags: Dominic Thorncroft, Dentist, Teeth, Dentistry

In biology Phylogenetics is the study of evolutionary relationships among groups of organisms (species and populations), which is discovered through molecular sequencing data and morphological data matrices. The term derives from the Greek terms “phyle” and “phylon” denoting “tribe” and “birth”. “Arthropods”-man, human and “ Logos” — is a science of humans in all the times and époques around all pleases of the Earth.

In 1859 Darwin described Neanderthals. Later in 1924 Magnon founded pithecanthropus erectus and Milford created the human evolution model. Physical anthropology is one of the most important divisions of phylogeny and it is defined as a science of humans in biological aspect: origin, anatomy and physiology of the different nationalities.

Other branches are paleontology, anthropometry and Forensic anthropology. Paleontology (from Greek means “old, ancient’’) is a study of fossils to determine organisms’ evolution and interactions with each other and their environments — paleoecology.

As a historical science it explains causes rather than conducting experiments to observe effects. Body fossils and trace fossils are the principal types of evidence about ancient life, and geochemical evidence has helped to investigate the evolution of life before there were organisms large enough to leave fossils. The objects of investigation of paleo dentistry are: teeth anatomy, skeleton variations, TMJ and cheek — bone remodelling and craniometry.

The specific parts are observations on Carabelli George cusp, spacing and diastema; groves depths, dental crowns eminence and dental caries and erosions appeared in different types of humans. Construction of a phylogenetic evolution is regarded as a branching process, whereby populations are altered over time and may specialize into separate branches, hybridize together or terminate by extinction; this may be visualized in a phylogenetic tree.

Construction of a phylogenetic evolution is regarded as a branching process, whereby populations are altered over time and may speciate into separate branches, hybridize together or terminate by extinction; this may be visualized in a phylogenetic tree. Medical anthropology has a long lasting development. It can be described as follows: early ages before 4,5 years characterized by the appearance of archeocraniobactery.

Next époque obtains the period before 3,5 years during which stromatolites and multicellular organisms appear. What follows is the Cambrian period. The evolution of fish, amphibians, reptilians, birds and mammals took a long period after which, before about 65 MLN years, evolution of primates started. The goal of anthropometry is to measure the physical characteristics of the people. The goal of Anthropometry is to measure the physical characteristics of the people. Phylogenesis (Phylum — order, class; genesis — origin) involves:

Morphological characteristics of organisms into categories and periods Morphogenesis;

Development and evolutionary history of species in taxonomic groups,

Origin and history of the evolution of species.

Taxonomy is a classification, identification and naming of organisms richly informed by phylogenetics, but remains methodologically distinct. The fields of phylogenetics and taxonomy overlap in the science of phylogenetic systematics — one methodology used to create cladograms and delimit taxa ( clades).

In biological systems as a whole phylogenetic analyses have become essential in researching the evolutionary tree of life. Stoma, cartilage, movable jaws, language and number of teeth (hypodontia and polifiodontia) are the most often used futures for classification.

Grouping of organisms is the main method — there are phylogenetic terms that describe the nature of a grouping in such trees. All birds and reptiles are believed to have descended from a single common ancestor so this taxonomic grouping is called monophyletic.

The evolutionary connections between organisms are represented graphically through phylogenetic trees. Due to the fact that evolution takes place over long periods of time that cannot be observed directly, biologists must reconstruct phylogenies of time inferring the evolutionary relationships among present — day organisms.

Phylogenetic relationships in the past were reconstructed by looking at phenotypes, often anatomical characteristics. Today, molecular data, which includes protein and DNA sequences are used to construct phylogenetic ranges. Paleogenesis gives us information about human organs.

For example: in Amphibians first mouth formation is found, in Reptiles — the palate, bone and glands appear first, in Crocodile — they are developed cement and periodontium can be observed for the first time.

Comparative anatomy is a part of Primatology investigating different human types as: humans from the Paleocene age, Australopitecus from Africa, Paranthropus , Neandertal, Homo erectus from Europe and Homo sapiens. Phylogenetics observes modern human epoques as Pleistocene, Upper Paleolitic, and Holocene.

The beginning of real Human evolution started before 4,5 MLN. God. , when bipedal primates have appeared. This period is characterized by human brain evolution. Before 45,000 years ago, the late glacial period developed. Cultural development, before 11,000 years, is the last period, involves industry, agriculture, science and mathematics evolution. This period is the beginning of contemporary urbanization.

The study of human dentition has raised the interest not only of the Dental community, but also Paleontologists, Anthropologists, Geneticists and has focused their attention to dental anatomy and phylogenesis of human dentition as result of an evolutionary process. The main goal is to study comparative anatomy, dental phylogenesis and anthropology which allows the dentist to understand present form and function of human dentition.

The shape of human dentition reflects all functions. Human dento-maxillary anatomy is the expression of the evolution of phylogenies. Human primates are featured by their incongruent TM joints and they are different in their acute angle of the articular heads. Ontogeny recapitulates phylogeny — the development of an organism exactly mirrors the evolutionary development of the species. This theory states that the embryo mirrors adult evolution.

During the last 19th Century, EH RTH was called a biogenetic law, most widely accepted. Ontogenesis — its origin and development of the human organism as individuality starts its development after the creation of a variety of theories. The most important are listed: Darwin Evolution Theory, Remark Cells Theory and Ernst Haeckel statement — Ontogenesis is a repetition of the phylogenies concerning the digestive physiological function and reproduction. History of the embryo is a base foundation of Embryology. Embryo drew Romanes in 1892.

Ontogenesis or morphogenesis — is the origin and development of an organism from the fertilized egg to its mature form. Term comes from the Greek “onto” — to be and from “geny” — mode of production. Ontogeny is defined as the history of structural change in unity, which can be a cell, an organism, or society of organisms, without the loss of the organization which allows that unity to exist.

The Theory of recapitulation, also called biogenic law or embryological parallelism often expressed as “ontogeny recapitulates phylogeny’’,is a hypothesis that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the evolution of their remote ancestors.

Several periods are important for the dentists as : nonfunctional and functional periods of life, intrauterine life prenatal (nonfunctional), embrional period, stomodeum development period, Mandibular and Maxillary growths period, Primary embryonic undershot — up to 2 months and Fetal period, characterized by primary embryonic progeny.

Functional periods are — period of secondary undershot, Orthognathic bite after break and to 6 months postnatal temporary dentition and Mixed dentition of 6–14 year. Teeth eruption is described by several theories as root theory, pulp theory, occlusal forces interaction, hormone kinetic theory and the increased hydrostatic theory.