ANÁLISIS DE LOS MECANISMOS DE VINCULACIÓN

Recording the dimensions o f the tooth crown is a method which had been used in the investigation o f dental variation in studies o f most mammal groups, including humans. In studies o f human teeth the dimensions usually taken are the buccolingual and mesiodistal diameters (Kieser 1990:4, Mayhall 1992:60). In terms o f measurements specific to the study o f Sus scrofa teeth in archaeological material, the most detailed set o f dimensions are those suggested and defined by Payne and Bull (1988). These represent an increase in the number o f dimensions recorded, compared with von den Driesch (1976). In addition, the measurements proposed by Payne and Bull include those for the deciduous

teeth. The measurements selected and described below are a combination o f those suggested by Payne and Bull (1988) and additional dimensions selected and developed specifically for this project. These additional measurements include those for both tooth widths and lengths. While Payne and Bull included width dimensions for the different lobes o f the molar (1988), they did not measure the constriction which delimited the two lobes, and this was felt to be a potentially important aspect o f shape.

Also, observations o f modem and archaeological teeth show that inter-dental wear identified at the contact point between the fourth deciduous premolar and the first permanent molar, leads to a reduction in tooth length with age. As Payne and Bull state “[t]ooth lengths, on the other hand, decrease by 4-7%, presumably as a result o f tooth wear and inter-dental attrition” (1988:30). These observations led to the inclusion o f an additional length measurement for the first permanent molar and the fourth deciduous premolar, taken at the point where the crown and root meet at the cementum enamel junction (CEJ). This cervical length represented a means o f recording tooth length

which was unaffected by wear in all but the final stages o f attrition.

In this project all dental measurements apply to mandibular teeth only. Tooth measurements require the use o f a model o f callipers with finer and longer points than standard callipers normally used by zooarchaeologists, for recording dimensions o f skeletal elements. The model selected for this study was a stainless steel Mitutoyo Digimatic, number 573-221-10. Measurements were taken in millimetres, and recorded to 0.01 mm. All measurements were entered into a database created with Microsoft Access 2, and then transferred to SPSS for Windows version 6.1, for statistical analysis.

Before describing the measurements taken it is helpful to define the terms used and the protocol employed. The mesiodistal axis runs fi'om the distal to the mesial contact point o f any tooth i.e. the points where the tooth abuts its neighbours. In individuals where malocclusion has produced contact points in positions different to normally occluded teeth, the point where the contact point would have been (in a normally occluded tooth) is used instead. Individuals with severe malocclusion are excluded from the sample. The (crown) length measurement o f any tooth is taken along the mesiodistal axis and can be referred to as the mesiodistal length. The width

For all measurements (apart from the cervical lengths) the calliper beam was held in a plane parallel to the occlusal plane (that in which a normally occluded tooth wears). For all lengths the calliper beam was aligned along the mesiodistal axis and for all widths it was aligned at right angles to the mesiodistal axis.

First permanent molar (Mj) measurements taken (Figures 4.1 and 4.2).

First permanent Molar Length (Mi L).

The greatest length o f the crown taken along its mesiodistal axis (after Payne and Bull 1988). The calliper beam was held in a plane parallel to the occlusal plane,

aligned along the mesiodistal axis. The points were placed on the contact points o f the mesial and distal ends o f the crown.

Ml Cervical Length (Mi CL).

The maximum length o f the tooth at the cementum enamel junction (CEJ), or cervical margin, where the root meets the crown. The points between which this measurement was taken were identified by a change o f colour, since the enamel o f the crown tends to be whiter than the cementum on the root. The CEJ did not remain at a constant height all the way around the circumference o f the tooth: at the mesial end it curved in an occlusal direction, whilst distally it dipped down apically. The points were placed where the mesiodistal axis bisected the CEJ. The measurement was difficult to take in cases where calculus had built up along the cervical margin, and impossible in cases where the tooth had not fully

erupted, unless it could be lifted slightly from the socket.

Maximum buccolingual width o f the anterior lobe o f the tooth (MiWA) .

The maximum width o f the anterior (mesial) part o f the crown, taken at right angles to the mesiodistal axis (after Payne and Bull 1988). The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest part o f the occlusal outline o f the mesial lobe o f tooth.

Figure 4.1 Measurements taken for the first permanent molar (M i)

Maximum buccolingual width o f the posterior (distal) lobe o f the tooth (Mi WP). The maximum width o f the posterior (distal) part o f the crown, taken at right angles to the mesiodistal axis (after Payne and Bull 1988). The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest part o f the occlusal outline o f the distal lobe o f tooth. In specimens where the tooth had not fully erupted, this measurement could not be taken.

Minimum buccolingual width o f the constriction which separated the mesial and distal lobes o f the tooth (Mi WMC).

This measurement was taken across the constriction which separated the two lobes, half way along the tooth. The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at either side o f the narrowest part o f the constriction which separates the two lobes o f the tooth.

Figure 4.2 The location o f the cementum enamel junction (CEJ), where the cervical length measurement is taken

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Measurements taken from the fourth deciduous premolar (dp 4) Figures 4.3 and 4.4.

The form o f the fourth deciduous premolar, was reflected in the measurements chosen.

Fourth deciduous premolar length (dp4 L).

The maximum length o f the crown taken along its mesiodistal axis (after Payne and Bull 1988). The calliper beam was held in a plane parallel to the occlusal plane, aligned along the mesiodistal axis. The points were placed at the mesial and distal contact points o f the crown.

Fourth deciduous premolar cervical length (dp4 CL).

The maximum length o f the tooth at the cervical margin or cementum enamel junction where the root meets the crown. The points between which this

measurement was taken were identified by a change o f colour, since the enamel o f the crown tends to be whiter than the root. The CEJ did not remain at a constant height all the way around the circumference o f the tooth: at the mesial end it curved in an occlusal direction, whilst distally it dipped down to apical, this fluctuation in the height was less pronounced than for the first molar. The points were placed where the mesiodistal axis bisected the CEJ. The measurement was difficult to take in cases where calculus had built up along the cervical margin.

Maximum buccolingual width o f the anterior lobe o f the tooth (dp4 WA).

The maximum width o f the anterior (mesial) part o f the crown, taken at right angles to the mesiodistal length. The calliper beam was held in a plane parallel with the occlusal plane, at right angles to the mesiodistal length. The points were placed at the widest part o f the occlusal outline o f the mesial part o f the tooth.

Maximum buccolingual width o f the posterior (distal) lobe o f the tooth.

The maximum width o f the posterior (distal) part o f the tooth taken at right angles to the mesiodistal axis o f the tooth (after Payne and Bull 1988). The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest point o f the distal part o f the tooth.

Figure 4.3 Measurements taken for the fourth deciduous premolar

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WP

Figure 4.4 More measurements taken for the fourth deciduous premolar

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WPC

WAC

Maximum buccolingual width o f the central lobe o f the tooth (dp4 WM).

The maximum width o f the middle part o f the tooth bordered by the posterior (distal) and anterior (mesial) constrictions. At right angles to the mesiodistal axis o f the tooth. The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest point o f the occlusal outline o f the central part o f the tooth.

Fourth deciduous premolar minimum buccolingual width o f the posterior (distal) constriction (dp4 WPC).

The minimum width o f the posterior (distal) o f the two constrictions, taken at right angles to the mesiodistal axis o f the tooth. The calliper beam was held in a plane parallel to the occlusal plane. The points were placed at the most narrow point o f the occlusal outline o f the distal constriction between the distal and central parts o f the tooth.

Minimum buccolingual width o f the anterior (mesial) constriction (dp4 WAC).

The minimum width o f the anterior (mesial) o f the two constrictions in this tooth, taken at right angles to the mesiodistal axis o f the tooth. The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the most narrow point o f the occlusal outline o f the mesial constriction between the central and mesial parts o f the tooth.

Measurements taken fo r the second and third deciduous premolars.

The second and third deciduous premolars are quite similar in form and hence the same set o f measurements were taken on each tooth type. Unlike the first molar and fourth deciduous premolar, these teeth are not molariform, but blade-like. Thus it was decided that simple length and width measurements would be sufficient.

Third deciduous premolar length (dp3 L).

The maximum length o f the tooth along the mesiodistal axis. The calliper beam was held in a plane parallel to the occlusal plane, aligned along the mesiodistal axis. The points were placed at the mesial and distal contact points o f the tooth.

Third deciduous premolar width (dps W).

The maximum width across the tooth crown, at right angles to the mesiodistal axis o f the tooth. The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest part o f the occlusal outline o f the tooth.

Second deciduous premolar length (dpi L).

The maximum length o f the tooth along the mesiodistal axis. The calliper beam was held in a plane parallel to the occlusal plane, aligned along the mesiodistal axis. The points were placed at the mesial and distal contact points o f the tooth.

Second deciduous premolar width (dp2 W).

The maximum width across the tooth crown, at right angles to the mesiodistal axis o f the tooth. The calliper beam was held in a plane parallel to the occlusal plane, at right angles to the mesiodistal axis. The points were placed at the widest part o f the occlusal outline o f the tooth.

Row lengths.

Row lengths were among the dimensions recommended by von den Driesch (1976). Row lengths were included in the range o f dimensions measured because it was felt they may be useful indictors o f the shortening o f the mandible - a response to domestication which has been documented in the pig and the dog (Clutton-Brock 1987:72). Two versions o f row length were chosen: the length o f the entire deciduous premolar row and the length o f the deciduous premolar row and the first molar.

Length o f deciduous premolar row (PRML).

The length o f the deciduous premolar row taken along the mesiodistal axis o f the teeth. The calliper beam was held in a plane parallel to the occlusal plane o f the tooth row. The points were placed at the distal contact point o f dp4 and the most mesial part o f dpi.

Length o f deciduous premolar row and the first molar (Mi PRML).

The length o f the deciduous premolar row and the first molar taken along the mesiodistal axis o f the teeth. The calliper beam was held in a plane parallel to the occlusal plane o f the tooth row. The points were placed at the most distal part o f Ml (where the contact point with Mi would develop) and the most mesial point o f dpi.