No significant difference in the levels of dental fluctuating asymmetry between hypoplastic and non-hypoplastic skeletal groups from the Joseon Dynasty (mid 15th-early 20th century), South Korea.

OBJECTIVES: As part of efforts to explore the relationship between linear enamel hypoplasia (LEH) and dental fluctuating asymmetry (DFA), DFA levels were compared between a hypoplastic group and a non-hypoplastic group. Since both LEH and DFA are pathological indicators of environmental stress which are represented by teeth, it was hypothesized that the hypoplastic group would exhibit higher levels of DFA than the non-hypoplastic group. DESIGN: Total of 136 sets of Korean skeletal remains from the Joseon Dynasty (mid 15th-early 20th century, South Korea) were used. To test the hypothesis, DFA levels of both groups were compared by two-way ANOVA after examining some issues related to FA research such as measurement error, type of asymmetry, and size dependence. RESULT: Contrary to the anticipations of many relavant studies, the hypothesis of this study was not supported (F=3.469, p=0.063). That is, the DFA levels of the two groups did not differ significantly, which implies that LEH and DFA do not occur concordantly. CONCLUSION: As to the reason for the result of the present study, it was speculated that (1) different kinds and/or degrees of stressors may influence the occurrence of LEH and DFA, or (2) traditional measuring methods used for DFA research may not reflect true DFA levels. Based on this study, it is recommended that both LEH and DFA should be utilized and reported independently in future research on the environmental stress and nutritional status of human populations.

The evolution of tooth wear indices.

Tooth wear--attrition, erosion and abrasion-is perceived internationally as an ever-increasing problem. Clinical and epidemiological studies, however, are difficult to interpret and compare due to differences in terminology and the large number of indices that have been developed for diagnosing, grading and monitoring dental hard tissue loss. These indices have been designed to identify increasing severity and are usually numerical. Some record lesions on an aetiological basis (e.g. erosion indices), others record lesions irrespective of aetiology (tooth wear indices); none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. It reviews the literature to consider how current indices have evolved and discusses if these indices meet the clinical and research needs of the dental profession.

["Golden proportion" and its application to calculate dentition].

Within an evolutionary process, the nature has created the standard of aesthetics - a "gold proportion" on the basis of which, the parts of human body, to be more exact, teeth and denture correspond to each other and to own parts by the size, which is the ideal precondition for ideal appearance. The charming smile serves as the proof, that teeth in denture are located by a principle of "gold proportion". A "gold proportion" is the corner stone of beauty and it can be applied with success in stomatology. Proportion is the certain ratio between parts, and proportional means a proper correlation of parts among themselves. It is reputed, that knowledge about "gold proportion" Pythagor has got from products of the Egyptian and Babylon scientists. And this is true, proportions of cult constructions, bas-relieves, pyramids in Giza, home appliances and ornaments from Tutanhamon tomb testify, that under their creation the Egyptian masters were guided by a principle of "gold proportion". The facade of ancient Greek temple Parthenon is built by a principle of "gold proportion". During archeological digs of this temple the compasses which sculptors and architects of an ancient world used has been found. The "gold proportion" is mentioned in the work which has reached us "Beginning" the author is the scientist of antique epoch Euclid. In 1509, in Venice the book of Luka Pacholi the "Divine proportion" has been published, its illustration is attributed to Leonardo de Vinci. This work has been recognized as a "Hymn of a gold proportion". In 1885 the German researcher professor Zeising published his work - "Aesthetic researches". When Zeising has received numerical values of piece length, he saw that they coincided with figures of some numerical sequence, which was offered by the great Italian mathematician of Middle Ages Fibonacci (or Leonardo Pisano). In his composition the "Abacus Book" Leonardo Fibonacci showed aforesaid sequence of numbers, by means of which he has explained the formula of duplication of rabbits. The specified sequence scientists have seen in many phenomena of the Universe. In sequence of Fibonacci, in some division of its term on previous, it is received irrational number 1,61803398875.., known as Fibonacci. It is used in the reduced, approximated kind as F = 1,618 or phi = 0,618. Fibonacci also gave a proportional number (...3:2, 5:3, 8:5, 13:8...), where numerator represents the sum of two previous numbers in Fibonacci sequence. And in proportional number, similar to numerical sequence, the result of any ratio will be approximately the same - this an irrational number which asymptotically comes to 1,61803398875.... Two numbers of Fibonacci sequence F = 1,618 or phi = 0,618 or phi = 1:F... represent constants of the same sequence. It is actual in stomatology to use proportional way. For example, in orthopedic stomatology taking into consideration of ratio 5:3, promotes improvement of basic fabrics tension, prolongation of teeth functioning and denture, and also planning of correct redistribution of chewing function. In 60th -70th years the American stomatologists carried out many researches to define what kind of part "gold proportion" takes in this area of medicine. Orthodontist Robert Rikets has established that separate teeth correlate with each other by a principle of "gold proportion". In his works Roberts Rickets has specified, that mentioned data is necessary to be considered in aesthetic stomatology during teeth reconstruction. An eminent stomatologist from California, the surgeon, doctor Shtefan Markvart has found out that the height of lateral incisors corresponds to width of lateral incisors by a principle of "gold proportion". This fact has helped the decision of many aesthetic problems. Knowing the width, it is easy to calculate the height and vice versa. When the width is optimum, it cannot be broken with the purpose of closing of an interval. The principle of "gold proportion" in connection with a denture consists in the following: the central incisors are hardly longer than lateral incisors and are almost equal to the length of canines: and lateral incisors are slightly shorter and thinner than the central incisors. The width and the length of each tooth is measured by compasses and calculated for each patient individually. According to a "gold proportion" fore-teeth as a part of person appearance are in the certain ratio to each other. The basic key for the description and construction of four incisors and two canines considers the size (which is accepted as unit) of the width of a small piece of teeth arch or a lateral incisor. On the basis of a lateral incisor width, by the formula of "gold proportion", it is formed the width of the central incisors and canines, and also the length of a fore-part of a dental arch, and vise versa if the length of a fore-part of a dental arch is known, to achieve an ideal aesthetic condition by a principle of "gold proportion", it is defined the width of all fore-teeth. Teeth measurement is taken to define an initial condition, denture calculation, verification of the received results during teeth construction and estimation of the complete denture reconstruction.

Dental morphology of the early Hoabinian, the Neolithic Da But and the Metal age Dong Son civilized peoples in Vietnam.

The early Hoabinian, the Neolithic Da But and the Dong Son (early Metal age) civilized peoples in northern Vietnam were investigated based on dental morphology and were compared with specimens from surrounding Northeast and Southeast Asia including Australians and Melanesians. In both the metric and nonmetric tooth traits, the Hoabinian and Da But specimens had dental features similar to the prehistoric Southeast Asians and the Australo-Melanesians, but also had partially Northeast Asian characteristics. On the other hand, the Northeast Asian features become distinct in the dentition of the Dong Son people, which have close ties with the modern Vietnamese. Thus, the Vietnamese, as well as the other modern Southeast Asians and Japanese, are considered to be a blend of indigenous Southeast Asians who are closely related to the Australo-Melanesian lineage, and migrants from Northeast Asia.

Dental maturation of 18th and 19th century British children using Demirjian's method.

AIM: To compare dental age with chronological age in a group of children born approximately 200 years ago and a group of modern children. METHODS: Dental maturation of 15 skeletal remains (range 3.0-15.1 years) of London children of known age-at-death was compared to an age and sex matched control group of contemporary children (n = 30). The method of Demirjian, Goldstein and Tanner (1973, 1976, 1978) was used to assess maturity. RESULTS: The difference between dental age (DA) and chronological age (CA) for both groups was not significant, suggesting similar maturation over 200 years, however, many of the younger children from Spitalfields were dentally delayed. Several of the younger individuals from both groups had a dental age less than the lowest limit of this scale (2.5 years), highlighting one pitfall of this method. CONCLUSION: These results suggest that this method is not entirely suitable for younger children.

Richard Owen and the comparative anatomy of teeth.

One hundred fifty years ago, Richard Owen published the first detailed monograph on the comparative anatomy of teeth entitled Odontography; or, A Treatise on the Comparative Anatomy of the Teeth; their Physiological Relations, Mode of Development, and Microscopic Structure, in the Vertebrate Animals. The treatise is considered to be the first fundamental work of odontology. The 150th anniversary of its publication is an appropriate time to rediscover the roots and development of this scientific discipline, as well as the life and work of its author.

Comparative anatomy of teeth from past to present.

The comparative anatomy of teeth has a long tradition in research, starting more than two thousand years ago in antiquity. In the 19th century, Richard Owen's oeuvre Odontography (1840-45) contributed much to establish odontology as an independent scientific discipline. After a short outline of the historical development of the comparative anatomy of teeth, we describe the contents and importance of Owen's Odontography. Finally, we sketch the contemporary situation of dental morphology, which in the course of the last thirty years has developed into an important and internationally highly recognized multidisciplinary field.

Increasing human tooth length between birth and 5.4 years.

Most previous studies of tooth development have used fractional stages of tooth formation to construct growth standards suitable for aging juvenile skeletal material. A simple alternative for determining dental age is to measure tooth length throughout development. In this study, data on tooth length development are presented from 63 individuals of known age at death, between birth and 5.4 years, from an archeological population recovered from the crypt of Christ Church, Spitalfields, London. Isolated developing teeth (304 deciduous, 269 permanent) were measured in millimeters and plotted against individual age. Regression equations to estimate age from a given tooth length, are presented for each deciduous maxillary and mandibular tooth type and for permanent maxillary and mandibular incisors, canines, and first permanent molars. Data on the earliest age of root completion of deciduous teeth and initial mineralization and crown completion of some permanent teeth in this sample are given, as well as the average crown height and total tooth length from a small number of unworn teeth. This method provides an easy, quantitative and objective measure of dental formation appropriate for use by archeologists and anthropologists.