Tooth Pitting Research Articles

The use of tooth pits to identify carnivore taxa in tooth-marked archaeofaunas and their relevance to reconstruct hominid carcass processing behaviours

Tooth marks on bones have been used as a proof of carnivore involvement in carcass modification in archaeological assemblages. Recognition of the array of potential carnivores that may intervene in the consumption of carcass elements accumulated at archaeological sites may condition the way archaeologists reconstruct hominid–carnivore interaction and resource availability for both types of taphonomic agents. The development of techniques aimed at discerning carnivore taxa according to tooth mark location and size has proven problematic so far. The present work introduces new information, based on the use of tooth pit size, to determine the types of carnivores that have modified bone surfaces. It is concluded that tooth marks alone cannot be used to differentiate among specific taxa, unless the analysis of tooth pits is carried out taking into account their distribution and ranges of variation in large samples, together with other variables, such as the location of tooth marks according to bone section and element, and the anatomical distribution of furrowing. Even so, the attribution of specific bone damage to determined carnivores can only be confidently made when comparing small-sized versus large-sized carnivores.

Perception of dental fluorosis amongst Ethiopian children and their mothers

This study was conducted in three Ethiopian Rift Valley villages known for endemic fluorosis. Three-hundred-and-six adolescents (12-15 years) and 233 mothers participated. The aim was to study dental fluorosis in the youngsters and to assess the extent of agreement between clinical and self-rated discoloration and pitting of teeth, and also the level at which dental fluorosis is perceived as a problem both by children and their mothers. The children (154 M and 152 F) gave a simple self-assessment of tooth-color and quality of their teeth, and were subsequently examined for dental fluorosis. Finally, four color photographs of teeth with dental fluorosis (TF-scores 2, 3, 5, and 7) were used as references during a structured oral interview of the children, as well as their mothers. At TF score S 2, the prevalence of dental fluorosis on maxillary central incisors was 72% and 37% at TF score S 4. The mean TF score was significantly higher among boys than among girls of unemployed fathers compared to children of employed fathers. The likelihood of reporting problems with dental appearance increased with increasing individual TF scores. The child/mother pairs found teeth with TF scores 2 and 3 esthetically acceptable, while teeth with TF scores 5 and 7 were considered unacceptable. Mothers were more critical of severe fluorosis than were their children.

Identifying the Involvement of Multiple Carnivore Taxa with Archaeological Bone Assemblages

Information on the number of carnivore taxa that were involved with archaeological bone assemblages is pertinent to questions of site formation, hominid and carnivore competition for carcasses and the sequence of hominid and carnivore activity at sites. A majority of early archaeological bone assemblages bear evidence that both hominids and carnivores removed flesh and/or marrow from the bones. Whether flesh specialists (felids) or bone-crunchers (hyaenas), or both, fed upon the carcasses is crucial for deciphering the timing of hominid involvement with the assemblages. Here we present an initial attempt to differentiate the tooth mark signature inflicted on bones by a single carnivore species versus multiple carnivore taxa. Quantitative data on carnivore tooth pits, those resembling a tooth crown or a cusp, are presented for two characteristics: the area of the marks in millimetres, and the shape as determined by the ratio of the major axis to the minor axis of the mark. Tooth pits from bones modified by extant East African carnivores and latex impressions of tooth pits from extinct carnivore species are compared to those in the FLK Zinjanthropus bone assemblage. Data on tooth mark shape indicate greater variability in theZinj sample than is exhibited by any individual extant or extinct carnivore species in the comparative sample. Data on tooth mark area demonstrate that bone density is related to the size of marks. Taken together, these data support the inference that felids defleshed bones in the Zinj assemblage and that hyaenas had final access to any grease or tissues that remained.

Origin and causes of the mammoth steppe: a story of cloud cover, woolly mammal tooth pits, buckles, and inside-out Beringia

To account for the vastness of the northern arid steppes during Glacial episodes, I propose the proximate key variable was simply frequent clear skies. This hitherto under-emphasized point is the hub which best explains many questions. Low maritime cloud cover best accounts for today's tundra, and in a related way, the cloudy Polar Front accounts for the whole of the taiga. Even during Glacial maxima, the proximity of the sea to the Bering isthmus created intermittent maritime cloud cover. This regional cloud cover produced an ecological interruption, or buckle, of the arid steppe belt. While this Beringian mesic buckle did not serve as an intercontinental ecological barrier to most steppe-adapted species, it does seem to have limited the distributions of woolly rhinos, camels, American kiangs, short-faced bears, badgers, and some others. At the beginning of the Holocene, this narrow refugium seems to have been a source of some mesic-adapted species which colonized westward into the now tundra vegetation of northern Asia and eastward into northern North America. This Holocene expansion from a limited and regional Pleistocene refugium created our present misconceptions about Beringia. The mid-strait mesic ecological conditions were the exception to the more extensive, arid-adapted, communities of the Mammoth Steppe.

Management of Immature Permanent Tooth Pit and Fissure Primary Caries

Management of Immature Permanent Tooth Pit and Fissure Primary Caries

Analysis of the effects of surface pitting and wear on the vibration of a gear transmission system

A comprehensive procedure to simulate and analyse the vibrations in a gear transmission system with surface pitting, wear, and partial tooth fracture of the gear teeth is presented. An analytical model was developed where the effects of surface pitting and wear of the gear tooth were simulated by phase and magnitude changes in the gear mesh stiffness. Changes in the gear mesh stiffness were incorporated into each gear-shaft model during the global dynamic simulation of the system. The overall dynamics of the system were evaluated by solving for the transient dynamics of each shaft system simultaneously with the vibration of the gearbox structure. In order to reduce the number of degrees-of-freedom in the system, a modal synthesis procedure was used in the global transient dynamic analysis of the overall transmission ststem. An FFT procedure was used to transform the averaged time signal into the frequency domain for signature analysis. In addition, the Wigner-Ville distribution was also introduced to examine the gear vibration in the joint time-frequency domain for vibration pattern recognition. Experimental results obtained from a gear fatigue test rig at NASA Lewis Research Center were used to evaluate the analytical model.

Scanning electron microscopy of trypsin-treated enamel from fluorosed rat molars.

Fluoride-induced pitting and porosity of teeth have long been observed, but little progress has been made in determining their origin. We have observed, in the trypsin-treated surfaces of enamel, pits that disappear on completion of maturation, following the removal of the protein matrix and full mineralization. Since these pits were considered to be similar to those seen in fluorotic teeth, this scanning electron microscope (SEM) study was undertaken to determine the effect of fluoride on these transient developmental pits during enamel matrix maturation. A group of 20 eight-day-old rats was given daily intraperitoneal injections of NaF (20 mg/kg [9 mg F-/kg] body weight) for five days. Twenty control animals received intraperitoneal injections of isotonic saline. Maxillary and mandibular molars were dissected from the 13-day-old animals, washed in HEPES buffered (Ca2+/Mg2+) free basal medium, Eagle's (BME), incubated in 3% trypsin/BME for 5-10 min at room temperature, then indirectly sonicated in BME for 2-4 min. Clean crowns were fixed in 2.5% glutaraldehyde for three hr, dehydrated, critical-point-dried, and sputter-coated for SEM. Pits in the surfaces of developing enamel were observed in all groups. In control teeth, the pitting was restricted to the cervical margin, whereas in teeth from the fluoride-treated animals, pits were observed on some cuspal surfaces in addition to the cervical margin. These results confirmed that pits in trypsin-treated surfaces of developing enamel are a transient developmental event and showed that, in the presence of a high dose of fluoride, the maturation of enamel is modified with retention of the pits.

Tooth pits: an early sign of tuberous sclerosis

The pit-shaped enamel defects seem to be pathognomonic of tuberous sclerosis and its detection may be an important help in the early diagnosis of this disease, especially in oligosymptomatic cases and when the dermatologic signs are still absent or only slightly evident.

Fluorosis in Deer (Odocoileus virginianus)

Above normal levels of fluorides were found in the bones of deer in the vicinity of an industrial complex. The sources of fluorides for the deer were water in a pond within the industrial compound and vegetation containing moderately increased levels of fluoride. Mandibular bone fluoride contents of 4300 to 7125 ppm. were associated with pitting and black discoloration of teeth, abnormal tooth wear and fractures of teeth and jaw bones.

The Effect of Lubricants on Gear Tooth Surface Fatigue

This paper presents some of the results of a recent investigation on the effect of lubricants on gear tooth surface fatigue (pitting). The work described comprises the development of a laboratory test procedure for exploratory purposes, and the determination of the performance of a number of lubricants using this procedure. It was found that bulk lubricant viscosity, as measured by the conventional viscometric method, did not have a predominant effect on gear tooth surface fatigue. Examination of the development of scuffing and pitting on the gear teeth indicates that the initial incidence of scuffing and the initial incidence of pitting were unrelated. It was further noted that as pitting became advanced, severe scuffing of the pitted teeth would almost invariably result. On the other hand, there was no evidence that severe scuffing would lead to gear tooth pitting. Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Toronto, Canada, October, 1957.