同口牙齿的磨耗级比较

本文比较和分析了同口同侧牙齿的相应的磨耗级,提供了除臼齿以外的牙齿磨耗年龄变化依据。同时还对上下对应牙、两侧对称牙的磨耗级作了比较和分析。     

以牙磨耗度和牙指数推算牙齿年龄的多元回归方程式的研究

本文对97例华南人M~I的磨耗度、牙指数和年龄三者之间的关系进行了深入探讨。并由此而提出以牙磨耗度和牙指数为两个变量的三元回归方程。比较分析结果表明,三元相关系数高于其它二元相关系数,三元回归方程的标准估计误差低于其它二元回归方程的标准估计误差。因而,以三元回归方程式比单纯以牙指数或牙磨耗度作为变量的二元回归方程式估计年龄准确。     

问题解答

问:人的乳牙是否全更换为恒牙?有的人认为:"小孩小时患龋齿没关系,反正到时要更换为恒牙",请问,这种说法对吗?(安散黄山二中胡健刚)答:人的一生要长两次牙,第一次长出20个乳牙,第二次长出32个恒牙,如下表所示:     

华南人颅骨上、下颌臼齿磨耗与年龄变化的关系

本文以华南人103例17—73岁男性颅骨的709个臼齿为材料,研究了上下颌臼齿磨耗度与年龄的关系。将磨耗度分为九级,统计分析结果表明,华南人臼齿的磨耗度与年龄关系是密切相关的,这种相关关系,能够作为估计华南人颅骨年龄的标准。第一臼齿与第二臼齿的磨耗平均年龄比率是M1∶M2=6∶6.9;磨耗度与年龄的相关系数M1为0.91,M2为0.90,均为高度相关。并得出磨耗度的平均年龄及95％置信区间(见表3)。华南人下颌臼齿的磨耗比上颌臼齿的磨耗稍大(61.5％)。     

郑州汪沟遗址仰韶文化居民的牙齿磨耗及口腔健康状况

对汪沟遗址出土的174例仰韶文化居民的2816枚牙齿进行统计与分析,计算出牙齿的平均磨耗等级和前后部牙齿磨耗差别指数,统计特殊磨耗、龋齿、骨质隆起在样本中的出现率。结果显示,汪沟组牙齿平均磨耗等级为3.403262级,男性牙齿平均磨耗等级为3.63级,女性为3.61级;男女两性牙齿磨耗差异不显著（p>0.05);前后部牙齿磨耗差别指数比达到1:1;出现26例由于深覆牙合导致的特殊磨耗;臼齿咬合面凹坑式磨耗出现率为2.50%;龋齿患病率68.97%,龋齿率26.56%,龋均4.30;骨质隆起的出现率为5.20%,颌骨粗壮程度不显著。汪沟人群的牙齿磨耗程度总体偏轻,牙齿磨耗程度与河南下王岗组居民接近。基于以上特点,我们认为中原地区仰韶文化人群在饮食结构和用牙习惯上存在一定的共性。     

儿童牙齿磨耗研究概述

牙齿磨耗是一个多因素、多阶段、复杂渐进的过程。其特征是牙齿硬组织逐渐消失,牙齿磨耗程度可以一定程度反映饮食结构和生活方式。国外很多学者探讨了年龄、性别、饮食结构、断奶、社会分工、社会经济地位等因素对儿童牙齿磨耗的影响,及乳齿恒齿磨耗差异、牙列磨耗模式特点、牙齿磨耗与错𬌗畸形的关系等,而国内儿童牙齿磨耗研究相对薄弱。本文通过梳理和归纳相关文献,对儿童牙齿磨耗研究作简要概述,并对国内相关研究作简要回顾及展望。     

新疆且末扎滚鲁克墓地二期居民的牙齿磨耗

本文对新疆且末扎滚鲁克墓地二期出土208例头骨上的1849枚牙齿进行了观察与研究。将所有个体按照年龄和性别分组,通过计算每个个体上颌或下颌骨上各牙齿相对第1臼齿的磨耗指数,分析各组之间相对磨耗指数的分布差异。经过与国内外不同人群的对比,对扎滚鲁克居民的牙齿磨耗模式特点以及可能存在的牙齿使用方式、行为特征等内容进行了初步探讨。结果显示,该人群的牙齿磨耗随着年龄增长显著增加,不同年龄组人群之间前后牙齿磨耗情况有很大的差异,牙齿磨耗在性别间差异并不显著。下颌个体出现了较为普遍的前牙磨耗比后牙偏严重的现象,这种现象主要集中在中年组下颌上。这种不寻常的下颌前牙磨耗较后牙偏重现象可能受到牙齿的工具性使用,牙齿萌出顺序以及年龄三方面因素共同作用的影响;中年个体下颌前牙磨耗的偏重现象可能反映了人群的行为特征。     

合水九站青铜器时代的人骨

本文报道的是甘肃省文物工作队于1984年10月至1985年12月在甘肃省合水县九站发掘出土的人骨。
我们发现根据牙齿磨耗度所估计的年龄值要比根据其它因素估计的年龄要高出10—15岁。这样大的差异可能主要是因为这里的人类的食物比现代人要粗糙得多,以及牙齿的耐磨程度都可能与现代人不同,因此牙齿磨耗也要重得多。我们参考骨缝愈合程度、齿槽吸收的情况及下颌角度等资料,进行必要的年龄校正,得出综合的年龄判断。     

华北人颅骨臼齿磨耗的年龄变化

在进行骨骼人类学研究时,首先要求对骨骼作出年龄的估计。在古人类或考古发掘中,或是在法医学和军事领域中,也常常需要根据人类骨骼,特别是颅骨的标本来作出年龄的估计。根据现有的知识,骨骼年龄的估计可从牙齿的发展和萌出,骨骺的出现和愈合,颅骨骨缝的愈合,牙齿的磨耗,以及骨骼的一般情况来作出。上述判断年龄的各种标准,大部分只能应用于成年以前的骨骼,在成年颅骨上,判断     

当代水族男性的牙齿磨耗特点及其成因

一直以来,有关人类牙齿磨耗的研究主要集中在年龄判定和生业方式比较方面。然而,很多研究因样本人群来源复杂、忽视个体牙齿磨耗的特殊性及缺乏足够的个人信息,很难进一步解释其牙齿磨耗特点的成因。本文基于对当代水族男性牙齿磨耗的记录和相关信息,通过梳理该人群牙齿磨耗的一般特点和特殊磨耗形式,探讨了有关影响该人群牙齿磨耗的可能因素。笔者发现,总体来说,该人群的牙齿磨耗较轻,牙齿磨耗水平与其年龄分布呈正相关关系,符合人类牙齿面随年龄增长而发生退行性生理磨耗的规律。牙齿磨耗等级在不同年龄中呈镶嵌式分布,某些个体存在越位磨耗现象。从本文的结果看,这些现象的产生除了退行性生理磨耗的原因外,还可能与口腔健康状况、饮食结构和少餐习惯等因素密切相关。     

Age determination of the African buffalo, Syncerus caffer Sparrman

Age criteria for the African buffalo are described. These are based on the tooth eruption sequence and on wear of the first molar. Assignment of absolute ages to the tooth eruption and wear classes has been made by reference to known-age animals and to numbers of cementum lines in tooth sections. For ageing animals to the nearest year, the normal degree of accuracy of the methods is assumed to be about ± 1/2year (1–5 years of age); about ± 1 year (5–15 years of age); and about ±2 years (15-20years of age). A field method of age determination is presented based on horn characteristics and relative body size.     

Field age determination of leopards by tooth wear

Age determination is an important tool in wildlife studies. Estimating the age of animals in the field using tooth wear criteria may be subject to error as a result of variations between individuals, habitats and populations. Data on age estimation of leopards and tooth wear characteristics are lacking. Nineteen leopards in Namibia were assessed for tooth eruption and wear. Between 1991 and 1995 leopards (including 13 individuals of known age) were monitored at one year intervals ('28 leopard years') to record age and tooth wear. At the age of two years leopards had fully developed dentition. Wear started with the incisors and canines, and spread to the premolars and molars. A chronology of tooth eruption and wear in relation to age is presented. Above the age of three years, male leopards showed higher frequencies of enamel flaking and canine fractures than females.     

Age estimation of the White rhinoceros (Ceratotherium simum)

Age estimation criteria for the southern White rhinoceros ( Ceratotherium simum simum ) are presented both for free-ranging live animals and for cranial material. These are based on: (i) size appearance and horn development of live animals; (ii) stages of tooth eruption; (iii) tooth wear classes; (iv) attrition in height of the first molar tooth; (v) counts of cementum lines visible in tooth sections. Selected measurements are presented for live animals, skulls and horns.
For live animals, eight size classes are distinguished, seven of these covering immature animals up to ten years of age. Sixteen tooth wear classes are established, based on eruption and surface wear of maxillary dentition. Chronological ages were assigned from individually known animals followed in the field, and from skulls from animals for which exact records of age were available, or which could be assigned to an age category from appearance at death. Cementum line counts corresponded approximately with age in years, despite difficulties in interpreting lines. Some variability was observed, possibly related to nutritional conditions.
The maximum cementum line count obtained indicates a longevity of at least 40 years. Full body weight and socio-sexual maturity are attained by males between 10 and 15 years of age, while females first give birth between six and eight years of age. Sequences and times of tooth eruption are similar to those reported for the Black rhinoceros ( Diceros bicornis ).
Comparative cranial and body measurements are presented for the northern subspecies ( Ceratotherium simum cottoni ).     

Determination of age in Cantabrian chamois (Rupicapva pyvenaica pavva) from jaw tooth-row eruption and wear

A tooth eruption and wear pattern useful to determine ten age classes when the horns are not available for this purpose, is described for Cantabrian chamois ( Rupicapra pyrenaica parva ) inhabiting the Cantabrian Mountains (north of Spain). In animals under eight years old, age is not significantly over- or under-estimated when using the method, however, the age of animals older than eight years is significantly under-estimated.     

Age determination and growth in the hyrax Procavia capensis (Mammalia: Procaviidae)

The use of eye lens weight, tooth eruption and tooth attrition has been investigated as a method for age determination in the hyrax. Illustrations are presented on the stages of eruption to reduce subjectivity of eruption criteria and to aid age determination. All teeth are fully erupted and in wear by five years of age, from which point age determination can be based on attrition of M3. Growth with age is described by means of the von Bertalanffy equation. Asymptotic weight is reached by 60 months, asymptotic body length and body girth by 40 months, and hindfoot length by 35 months. The asymptotes and the coefficient of catabolism (K) are compared with values obtained in other studies.     

Age determination ofGalemys pyrenaicus

This paper provides a criterion to determine the age of live Pyrenean desmansGalemys pyrenaicus (E. Geoffroy, 1811) by observing dental wear. The criterion is based on the comparison of the estimated age by examining the growth rings on dental sections and the wear observed on the upper canine tooth. Bone matter from different areas in the north of Spain was studied. This species has a high life expectancy. In its natural environment, the desman may live to be over 5 years old.     

Tooth wear and the position of the mental foramen

Variation in the position of the mental foramen with respect to the teeth ("apparent" position) seems to be associated with race, but in the determination of this position, factors which affect the disposition of the teeth plainly have a bearing on the results. The apparent position was investigated in a sample of southern Chinese skulls of known age which were classified by the degree of tooth wear. Controlling for "true" position and size of the mandible, a highly significant correlation between wear and position was found, age and tooth size having no significant contribution as additional explanatory variables. The effect of tooth wear on the apparent position of the foramen may partly explain racial variation.     

鹅喉羚的年龄鉴定

本文以鹅喉羚为材料,采用双重附贴磨片法及蚀刻法确定角磨片上显示的生长层与角鞘上凸“嵴”的关系,并以第一下门齿(I_1)作切片所显示的年轮线进行验证。证明其角鞘上的凸“嵴”数量多少并不表示年龄大小,在一龄内无凸“嵴”,二、三龄均包含有4—5个凸“嵴”,四龄后亦为2—3个凸“嵴”组成一龄,真正的年龄线是角表凸“嵴”之后有一粗糙微凹的环纹。实验结果可应用于野外生态学调查,用以判断种群年龄及结构。     

Age determination in roe deer — a new approach to tooth wear evaluated on known age in dividuals

A novel, simple, and objective method is presented for ageing roe deerCapreolus capreolus (Linnaeus, 1758) evaluated on 471 lower jaws from roe deer of known age (351 with permanent premolars). It is based on tooth eruption patterns and presence/absence of wear characters in jaws from roe deer integrated in a scoring system. Permanent cheek teeth emerge in May–July in the year af ter birth, which enables precise age determination of individuals with deciduous premolars. For individuals with permanent cheek teeth, the method provides the correct age for all individ uals younger than 13 months and > 80% of all individuals between 13 and 24 months old. For older in dividuals the accuracy decreases, but decent accuracy is achieved to the age of 48 months. Males have higher wear rates than females corroborating recent documentation of sex-specific life history tactics in ungulates. The data originate from two separated Danish roe deer populations exposed to contrasting habitats, but no difference in wear rate is found between populations. Thus, previous concern about the validity of age determination methods based on tooth wear may have been overstated. The findings demonstrate that objective measures of tooth wear can provide the basis for age determination in ungulate species that are otherwise difficult to age.     

Deciduous dentition and eruption pattern in late Miocene Pachyrukhinae (Hegetotheriidae,Notoungulata) from La Pampa Province,Argentina

The study of juvenile remains of Paedotherium Burmeister from Cerro Azul Formation (La Pampa Province, Argentina; late Miocene) is presented. Upper and lower deciduous dentition (or permanent molars supposed to be associated with non-preserved deciduous teeth) are recognised. Several ontogenetic stages are distinguished among juveniles, according to the degree of wear and the replaced deciduous teeth. Besides, some morphological and metrical differences are observed along the crown height. Deciduous cheek teeth are high-crowned and placed covering the apex of the corresponding permanent tooth. The height of the crown and the degree of wear allow establishing the pattern of dental replacement of deciduous and permanent premolars in a posterior–anterior direction (DP/dp4–2 and P/p4–2), as well as the eruption of M/m3 before DP/dp4 is replaced. Some of the studied remains are recognised as young individuals of Tremacyllus Ameghino, but with complete permanent dentition, which leads to propose a different timing in the dental replacement with respect to Paedotherium; they also allow the establishment of an opposite premolar eruption pattern, from P/p2 to P/p4. This knowledge of the deciduous dentition of Paedotherium suggests the need of revising the morphological and metrical characters previously used for defining species within this taxon.