Traumatic injury to the incisive bones and maxillary dentition in a male gray wolf (Canis lupus L.) from Slovakia

The paper presents the skull of a male gray wolf shot in the region of Snina, eastern Slovakia. Age at death of the wolf was estimated at 6 years. The skull was characterized by the almost-complete absence of the alveolar processes of the incisive bones and multiple dental abnormalities that were attributed to a severe trauma. All maxillary incisors and both maxillary first premolars were missing. In addition, both maxillary canines were fractured with only tooth fragments being left. The pulp exposure associated with the crown fractures of the maxillary canines had caused pulp necrosis and periapical lesions, as evidenced on radiographs. The right P², P³, and P⁴ were fractured, with only the remaining tooth structure of the second and third premolars being left. In the right P⁴ and the left M¹, periapical bone resorption was diagnosed radiologically. In the mandibular dentition, the right I₂ and left P₁ had been lost in life. The mandibular canines exhibited distinct wear facets that were caused by contact with the maxillary third incisors, which were subsequently lost. The fact that all fractured teeth showed signs of wear indicates that the trauma had occurred some time before the wolf was shot.     

Evaluation of compressive strength in the first premolars between young and elderly people: ex vivo study

doi: 10.1111/j.1741‐2358.2011.00583.x Evaluation of compressive strength in the first premolars between young and elderly people: ex vivo study Objective: This study evaluated the compressive strength of first maxillary premolars from young and elderly people. Background: Findings have revealed that changes happening on dental structure lead to a higher susceptibility of tooth fracture. Materials and methods: Thirty teeth were divided into four groups as follows: G I (n = 7) premolars of elderly patients with fused roots, G II (n = 8) premolars of elderly with separate roots, G III (n = 7) pre‐molars of young people with fused roots and G IV (n = 8) premolars of young people with roots separated. The roots were placed in polyvinyl chloride (PVC) cylinder and embedded in acrylic resin. Afterward, the samples were subjected to fracture by compressive strength in a universal testing machine. Loads were applied in continuous and progressive speed of 0.5 mm/min until the moment of fracture. The values found underwent statistical analysis (anova α = 0.05). Results: With regard to age, there was a statistical difference, the teeth of the elderly being more susceptible to fracture (p < 0.05). With regard to root morphology, no significant differences between both groups were observed (p > 0.05). Conclusion: It was concluded that with the methodology employed, the age factor was important with regard to fracture resistance to compression.     

Odontometry of a Spanish neolithic-Bronze age sample. Comparison with other populations of the iberian peninsula. I.-Permanent teeth

The present study concerns the morphometric characteristics of two hundred permanent teeth from the Neolithic-Bronze Age human remains found in «Galería del Sílex» (Atapuerca Cave, Burgos, Spain). The crown index reveals that all the upper maxillary teeth (except incisors) and the mandibular first incisors, canines and premolars have a vestibulo-lingual diameter greater than the mesio-distal. The dental module and the surface value show that the mandibular teeth (except the molars) are smaller than those of the upper maxillary. These results are very similar to other European populations. Finally, the Sílex Gallery sample was compared with five other series of the Iberian Peninsula which have a chronology from the Mesolithic to the Middle Age. The results indicate a general decrease for both diameters (ØMD and ØVL) throughout time.     

Sex differences in tooth wear ofMacaca fuscata,the Arashiyama-A troop in Texas

The incidence of tooth wear was studied in a wild troop ofM. fuscata, that had previously been transplanted from Arashiyama, Japan, to Texas. This study was undertaken to determine differences of attrition between males and females, and between maxillary and mandibular dentitions. Contrary to other findings, the rate of wear was not found to be an expression of sex difference, but seemed rather related to function. The following observations may suffice as examples: The mandibular third premolars function as a honing surface for the maxillary canines, and experience greater wear over time in males due to their proximity to smaller canines which leave their neighbors more vulnerable to wear. The degree of attrition intensity is neither the same for males and females, nor the maxillary and mandibular dentitions. Certain maxillary and mandibular teeth “pair up”; although all “pairs” are identical in males and females, they rank differently in the degree of wear experienced. Overall, females express greater attrition in the maxillary, and males in the mandibular dentitions.     

Permanent tooth emergence in Gujjars of Punjab, India.

Patterns of permanent tooth emergence in Gujjars were studied in a cross-sectional sample of 483 children ranging in age from 6 to 13 years. Females were markedly advanced in permanent tooth emergence times over males, but no such sex differences were observed in sequence of emergence. Differences between median emergence times of right and left side antimers were significant for only 4 of 28 instances (14.29%), namely central incisors, mandibular first molars in males and lateral maxillary incisors in females. In general mandibular teeth except premolars tended to emerge earlier than their maxillary counterparts. The quiescent period between first and second tooth emergence stages was longer in males than in females. Mandibular depth and morphological facial length were very significantly correlated (p < 0.01) with the number of permanent teeth present in the oral cavity.     

Brief communication: Emergence chronology of permanent teeth in Nigerian children

This study measured the mean age, duration, and sequence of the emergence of permanent dentition in Nigerian children and compared the findings with other population groups. The cross‐sectional study involved 1,078 Nigerian children, aged 4–16 years old, from selected primary and secondary schools in the Ife Central local government area in Ile‐Ife, Osun State. In general, compared to boys, girls had an earlier mean age of emergence of all the permanent teeth. Children from high socioeconomic class had an earlier mean age of emergence for the maxillary incisors (6.43 and 7.58 years) and mandibular incisors (5.28 and 6.44 years) compared to children from middle and low socioeconomic classes, although socioeconomic effects were more mixed for premolars and molars. Compared to their counterparts in the USA, Australia, Belgium, and Iran, Nigerian children showed an earlier mean age of emergence of all the permanent teeth studied except for Pakistani boys, who had an earlier mean age of emergence of the maxillary premolars and second molar. Poorer economic status has been associated with delayed dental development; however, when compared to other populations, the Nigerian children in this study have earlier mean emergence ages than children from wealthier countries such as the USA and Australia. Am J Phys Anthropol 153:506–511, 2014. © 2013 Wiley Periodicals, Inc.     

Tooth eruption in Reeves' muntjac (Muntiacus reevesi) and its use as a method of age estimation (Mammalia: Cervidae)

The sequence of tooth eruption and replacement in Reeves' muntjac was determined from captive animals of known age. Pronounced sexual dimorphism is shown by the permanent upper canine which in the male is large, tusk-like and is used as a weapon. The upper canine was the first deciduous tooth to be replaced in males, at approximately 21 weeks of age, compared with 53–57 weeks in the female. The permanent mandibular teeth erupted in the order: molars, first and second incisors, premolars, third incisor and canine. The maxillary teeth erupted in the order: first molar, canine (in male), second and third molars, canine (in female), premolars. The full complement of 34 functional permanent teeth was attained by 83–92 weeks of age.     

Disproportionate eruption of maxillary and mandibular incisors in the long-tailed ground squirrel

The surface of the maxillary and mandibular incisors of Spermophilus undulatus long-tailed ground squirrels, including those born in the current year and those that have hibernated (trapped one month or later after hibernation) is studied. The presence of daily growth increments on the incisors’ surface allows the evaluation of the eruption rate of the incisors; a specific change in the character of the growth increments corresponds to winter hibernation (hibernation zone), which serves as the time mark. Ratio between the eruption rates of the maxillary and mandibular incisors typical for rodents is found in young-of-the-year and some animals after hibernation. In these animals the eruption rate of the mandibular incisors is higher than the eruption rate of the maxillary incisors and can be taken as proportional to their length. In individuals that have hibernated and show proportional eruption of the incisors, the proportions of the total length of the incisor formed before hibernation zone are equal for the maxillary and mandibular incisors. In the individuals that also have hibernated and show the ratio between the total length of the maxillary and mandibular incisors typical for rodents, the eruption rate of the mandibular incisor is equal to or less than the eruption rate of the maxillary incisor and the proportion of the incisor formed before hibernation is greater in the mandibular incisor than in the maxillary. This disproportionate pattern of incisor eruption is not typical for rodents and is a result of inequal attrition of the maxillary and mandibular incisors, which ultimately results in the normal ratio of the total length of the maxillary and mandibular incisors.     

Association of relatively delayed emergence of mandibular molars with molar reduction and molar position

Among 234 children examined annually from age three to 20 years at the Burlington Growth Centre, there was statistically significant cooccurrence of early and late emergence sequences of the permanent first and second molars relative to the central incisors and second premolars in the same jaw and in both jaws. Alternatively, mandibular molar delay was not accompanied by corresponding maxillary molar delay, and the mandibular molars emerged later than the maxillary molars. This was strongly associated with Angle Class II malocclusion, indicating a relationship between relative time of emergence and relative position of opposing molars. Delay of the mandibular molar relative to the successional teeth or maxillary molars was associated with increased frequency of four cusped first and second molars and agenesis of third molars, indicating a tendency for co-occurrence of delay in timing of molar emergence with reduction in structure of the molars. These relationships were evident even though emergences were affected by early loss of a deciduous second molar which increased M1I1 and M2P2 sequences by earlier emergence of M1 and delayed emergence of P2.     

Effect of double flasking and investing methods on artificial teeth movement in complete dentures processing

doi: 10.1111/j.1741‐2358.2011.00494.x
Effect of double flasking and investing methods on artificial teeth movement in complete dentures processing Purpose: The aim of this study was to evaluate linear dimensional alterations of artificial teeth for complete dentures when using different investment and flasking techniques. Background: Dimensional changes in the vertical dimension may occur owing to changes in artificial teeth positioning caused by different investing and flasking techniques. Materials and methods: Thirty pairs of the complete dentures were manufactured and randomly divided into three groups (n = 10): (1) invested with type III stone in monomaxillary PVC flask; (2) invested with type III stone in bimaxillary PVC flask; and (3) invested with laboratory silicone in bimaxillary PVC flask. Dentures were polymerised by microwave, and 12 linear distances were measured before and after denture processing. Data were analysed by one‐way anova , considering manufacturing technique as the study factor. Tukey’s HSD was used as post hocanova (p = 0.05). Results: Most of the linear distances were comparable for all groups. All transversal maxillary and mandibular distances were higher for group 1 compared with groups 2 and 3 (p < 0.05), except the distance 3–6 for mandibular arch, in which no difference was found between groups (p < 0.05). Both maxillary diagonal distances were higher in group 1 (p < 0.05), and no differences were found among all groups for mandibular measurements. Conclusions: Double flasking technique independent on the investment material is shown to be the most effective method to reduce changes in artificial teeth positioning.     

Some dental traits of Diaguitas Indian skulls

Dental characteristics were studied on 60 skulls that belong to a population of Diaguitas Indians of approximately the Tenth Century. Mesiodistal crown diameters of permanent teeth were as follows: central incisors (8.77 mm), lateral incisors (7.23 mm), canines (8.40 mm), first maxillary molars (10.77 mm), second maxillary molars (10.71 mm), first mandibular molars (11.13 mm), and second mandibular molars (10.17 mm). Also determined was the frequency of shovel shaped incisors (80.30%), groove and cusp patterns of mandibular molars (Y5 73.40%), groove and cusp patterns of maxillary molars (H4 87.25%), and mesiopalatal version of maxillary incisors (66.20%). No skull showed Carabelli's cusp. The findings were compared with those for different populations past and living. The results suggest that the affiliation of the population analyzed was mongoloid.     

Age-related variability in occlusal wear planes

Investigation of two populations of 136 individuals shows several patterns of occlusal wear plane change which are positively correlated with age. For individuals up to the age of 18, there is a characteristic pattern in which the occlusal wear planes of the mandibular teeth are lingually sloped and those of the maxillary dentition buccally sloped, with the exception of the maxillary premolars, which are also lingually sloped. The long axes of the mandibular teeth give them a lingual orientation relative to the maxillary teeth, and the long axes of the maxillary molars, by contrast, are buccally oriented. In the 18-30 age range for all sexes, the mandibular M1 becomes buccally sloped on its occlusal surface while the occlusal wear plane on the maxillary M1 becomes lingually sloped. Later age changes indicate a trend for the mandibular premolars to become buccally sloped, while the wear planes of the maxillary premolars remain lingually sloped. There is a corresponding tendency for the maxillary and mandibular second molars to undergo changes in the initial orientation of the occlusal wear planes.     

金属烤瓷全冠修复老年人活髓隐裂牙适应证及临床疗效

目的：探讨老年人活髓隐裂牙应用金属烤瓷全冠修复临床效果及适应症。方法：选取本院2006年1月至2011年1月期间收治的356例老年活髓隐裂牙合计621颗为研究对象,根据患牙疼痛程度随机将患者分为咬合疼痛组（A组）104例合计215颗患牙,咬合伴过敏性冷热刺激痛组（B组）122例合计232颗患牙,咬合伴延续性冷热刺激疼痛组（C组）130例合计174颗患牙,所有患者均接受金属烤瓷全冠修复,观察患者在治疗后1个月、6个月、12个月、18个月、24个月治愈情况以及牙髓及根尖周病变及牙髓发生情况。结果：与C组相比,A组、B组术后1个月、6个月、12个月、18个月、24个月治愈率以及总有效率较高,差异有统计学意义（P〈0．05）。结论：金属烤瓷全冠修复适合于轻微咬合疼痛以及咬合伴过敏性冷热刺激痛的患者,而对于咬舍伴延续性冷热刺激疼痛的患者则宜先行根管治疗术再进行全冠修复。     

Incremental enamel development in modern human deciduous anterior teeth

This study reconstructs incremental enamel development for a sample of modern human deciduous mandibular (n = 42) and maxillary (n = 42) anterior (incisors and canines) teeth. Results are compared between anterior teeth, and with previous research for deciduous molars (Mahoney: Am J Phys Anthropol 144 (2011) 204-214) to identify developmental differences along the tooth row. Two hypotheses are tested: Retzius line periodicity will remain constant in teeth from the same jaw and range from 6 to 12 days among individuals, as in human permanent teeth; daily enamel secretion rates (DSRs) will not vary between deciduous teeth, as in some human permanent tooth types. A further aim is to search for links between deciduous incremental enamel development and the previously reported eruptionsequence. Retzius line periodicity in anterior teeth ranged between 5 and 6 days, but did not differ between an incisor and molar of one individual. Intradian line periodicity was 12 h. Mean cuspal DSRs varied slightly between equivalent regions along the tooth row. Mandibular incisors initiated enamel formation first, had the fastest mean DSRs, the greatest prenatal formation time, and based upon prior studies are the first deciduous tooth to erupt. Relatively rapid development in mandibular incisors in advance of early eruption may explain some of the variation in DSRs along the tooth row that cannot be explained by birth. Links between DSRs, enamel initiation times, and the deciduous eruption sequence are proposed. Anterior crown formation times presented here can contribute toward human infant age-at-death estimates. Regression equations for reconstructing formation time in worn incisors are given.     

Precise chronology of differentiation of developing human primary dentition

While correlation of developmental stage with embryonic age of the human primary dentition has been well documented, the available information regarding the differentiation timing of the primary teeth was largely based on the observation of initial mineralization and varies significantly. In this study, we aimed to document precise differentiation timing of the developing human primary dentition. We systematically examined the expression of odontogenic differentiation markers along with the formation of mineralized tissue in each developing maxillary and mandibular teeth from human embryos with well-defined embryonic age. We show that, despite that all primary teeth initiate development at the same time, odontogenic differentiation begins in the maxillary incisors at the 15th week and in the mandibular incisors at the 16th week of gestation, followed by the canine, the first primary premolar, and the second primary premolar at a week interval sequentially. Despite that the mandibular primary incisors erupt earlier than the maxillary incisors, this distal to proximal sequential differentiation of the human primary dentition coincides in general with the sequence of tooth eruption. Our results provide an accurate chronology of odontogenic differentiation of the developing human primary dentition, which could be used as reference for future studies of human tooth development.     

On the relative frequencies of hominid maxillary and mandibular teeth and jaws as taphonomic indicators

In southern African samples of early hominid remains, maxillary and mandibular teeth (deciduous-plus-permanent) have a virtually equal chance of accumulating in the dolomitic limestone cave deposits, of being preserved therein and recovered therefrom. Thus, of 1066 fossil teeth ofAustralopithecus spp. plusHomo habilis, 51.9 per cent are maxillary and 48.1 per cent mandibular. On the other hand, the East African sample of 847 early hominid, deciduous-plus-permanent teeth, departs more strikingly from a 1∶1 ratio: it comprises 41.0 per cent maxillary and 59.0 per cent mandibular teeth. It is inferred that mandibular teeth have a somewhat better chance of accumulating and being preserved in, and being recovered from, the open, fluvial, lacustrine and deltaic sedimentary environments of the East African sites. The dental proportions are approximately matched by the proportions of jaws. For example, the maxilla: mandible proportions at Koobi fora in northern Kenya are 33.0∶67.0 for teeth and 21.6∶78.4 for jaws. In other words, the preponderance in favour of mandibular remains is somewhat more marked in the case of jaws than of teeth, this distinction doubtless reflecting the more fragile bony structure of the maxilla and the sturdier construction of the mandible. This first study known to the author of the differential distribution of maxillary and mandibular teeth of the Plio-Pleistocene hominids leads the author to hypothesize that, where environmental conditions at the place and time of the death of the hominids have been non-destructive, non-dispersive, relatively mild and protective, maxillae and mandibles may be expected to have been conserved and recovered in approximately equal proportions—and likewise of maxillary and mandibular teeth. On the other hand, the more brutal and destructive the sedimentary environment and other taphonomic influences have been, at the place and time when the hominid individuals died, the more likely it is that the maxillary and mandibular remains of jaws and teeth will deviate from equality of proportions, generally at the expense of the maxillae and upper teeth. Hence, it is proposed that the upper jaw/low jaw ratio (Mx/Mn jaw ratio) and the maxillary teeth/mandibular teeth ratio (Mx/Mn dental ratio) may serve as two useful new gauges of the rigour of palaeo-ecological and taphonomic conditions.     

Enamel hypoplasias as indicators of developmental stress in pongids and hominids

This paper reports the results from a study of enamel hypoplasia in the deciduous dentition of free-living Liberian chimpanzees (Pan troglodytes verus). The entire study collection includes 280 specimens (278 skulls plus two unassociated mandibles), of which 70 are young enough to retain some decidous teeth. Among the subsample of infants, the total frequency of hypoplasia summed over all teeth in any individual reaches 80%, being expressed in the form of pits rather than transverse lines. Hypoplasia of a linear form was common in the permanent dentition, attaining a frequency of 46.7% on maxillary central incisors and 69.7% on mandibular canines.     

Morphological features of Jat dentition

Observations on morphological characters of milk and permanent teeth, based on 648 pairs of dental casts of 356 male and 292 female Jat children of Haryana (India) are reported. Deciduous teeth show high frequencies of bilateral winging of maxillary central incisor, Carabelli's cusp of maxillary second molar, and deflecting wrinkle of mandibular second molar. Reduction of maxillary molar cusps is more marked in males than in females. Y pattern is very common in deciduous molars. Permanent teeth have high frequencies of grooved cingulum of incisors, cingular nodule of lateral incisors and canines, and distal accessary ridge of canines. Low frequencies of Carabelli's cusp and winging are also common. The tendency towards faintly developed shovelling in milk incisors occurs more often than in the permanent teeth.