Text III. Oral structures anomalies in ancient times

The known types of developmental disorders manifested in teeth and bone can be represented in samples from antiquity.

The discovery of the oldest evidence of a human hereditary genetic disorder has been announced by researchers at the Hebrew University of Jerusalem. The authors of an article in the June issue of the Journal of Human Evolution detail the finding of a disease known as amelogenesis imperfecta in the teeth of a fossil found in archaeological excavations in Ethiopia. The fossil is dated as 1.5 million years old and is from a two-year-old Homo erectus child. Homo erectus was a precursor of modern man. According to Dr.Zilberman, this is the first recorded evidence from such an early prehistoric period of a hereditary disorder in which the specific genes responsible have been identified. Undoubtedly, he said, there are other hereditary diseases that have come down to us from prehistoric ancestors and which are yet to be discovered in fossil remains.

Amelogenesis imperfecta is a hereditary disorder that manifests itself in tooth enamel that is abnormal in structure, low in mineral content and hence subject to rapid wear and chipping. The Hebrew University researchers confirmed the clear presence of the disease in the fossil sample through x-ray and scanning electron microscope analyses. The disease appears relatively rarely today (one in 14,000 people in Israel, one in 8,000 in the U.S.). It is much more common in one area of Sweden (one in 700).

Enamel hypoplastic defects were found in the teeth of Pithecanthropus.

Manifestations of disturbances in tooth number include anodontia (absence) and supernumerary teeth (additional). Partial anodontia was noted throughout the various periods and cultures to the present day. In the Neolithic culture, particularly in Europe, there was an increased frequency of absence of third molars at a level which made that state relatively common.

Anthropologists from Medical Research University of Johannesburg, South Africa, reported the data that the maxillary dental arch of a partial cranium of an adult specimen of Australopithecus robustus shows the presence of a supernumerary tooth between the right first and second incisors. The fossil specimen is considered, on the basis of associated fauna, to be approximately 1.7 million year old.

A high occurrence of supernumerary or extra teeth was revealed in the remnants dating back to the Gallo-Roman period and Middle Ages.

Speaking

Choose any of the oral structures anomalies to dwell on. Speak on the frequency of its occurrence, predisposing factors, possible complications and prognosis.

Unit VIII. Human habits as a cause of the oral structures

Disturbances.

Lead-in

In every organ and tissue in the body, nature provides a wide margin of safety. The teeth and their supporting tissues are no exceptions. There are many cases when teeth become victims of excessive use and even of abuse far beyond any margins of safety. There are oral habits and, sometimes, neglect in which the use of the teeth causes a structural or functional anomaly.

Reading

Harmful habits

Habits are generally considered repeated acts of unspecified motivation. They will be treated as consciously repeated acts here. As such they fall into two classes; (1) occupational and (2) nonspecific.

In the case of occupational habits, many callings require the use of the teeth and mouth in an active or passive role. Musicians who play wind instruments, glass blowers, furriers, and many others use the mouth or teeth or both, either by necessity or for convenience. The type of breakdown will vary with the type of abuse inflicted.

The habits of sucking the thumb, lip, or tongue, so frequently formed by young children will, if persisted, cause marked malocclusion.

Fortunately, the habit of thumb-sucking is usually broken before any evil effects result, so that cases are easily recognized. The upper incisors and canines are drawn forward and to one side, according as the thumb of the right or left hand has bean used, while pressure from the back of the thumb upon the lower incisors causes their displacement.

The habit of biting the lower lip will move the upper central incisors. This habit is more common than seems.

The habit of sucking the lower lip, though quite rare, may produce marked malocclusion. The upper lip becomes short and contracted, the gums highly colored, and the lower lip becomes larger than normal.

Third National Health and Nutrition Examination Survey was conducted in the USA in 1988 to 1994. Participants were interviewed about tobacco use and examined by dentists trained to use standardized clinical criteria. It was calculated that 41.9% of periodontitis cases (6.4 million cases) in the U.S. adult population were attributable to current cigarette smoking and 10.9% (1.7 million cases) to former smoking. Among current smokers, 74.8% of their periodontitis was attributable to smoking. According to the findings of this study and numerous other reports, it is possible to conclude that smoking is a major risk factor for periodontitis and may be responsible for more than half of periodontitis cases.

Grammar