Evidence of pulp disease in the inlayed teeth of the ancient Mayans: a micro-ct study

Transcription

1 Evidence of pulp disease in the inlayed teeth of the ancient Mayans: a micro-ct study M. A. Versiani 1, J. D. Pécora 1, M. D. Sousa-Neto 1 1 Department of Restorative Dentistry, Faculty of Dentistry, University of São Paulo, Avenida do Café s/n, Ribeirão Preto, São Paulo, Brazil, CEP Aims Root canals and their associated pulp chamber are the physical hollows within a tooth that are naturally inhabited by nerve tissue, blood vessels and other cellular entities, named pulp tissue. In a situation that a tooth is considered so threatened and infection of the root canal space is considered inevitable, the removal of the pulp tissue is advisable to prevent such infection that could lead to necrosis, calcification or internal resorption. Calcification is considered as the hardening of decaying of dead soft tissue represented by calcified nodules or amorphous deposits in the pulp, and the internal resorption as a condition when the dentine and pulpal walls begin to resorb centrally within the root canal 1. An old and fascinating human practice, body ornamentation can be achieved through a variety of means including clothing, piercings, tattooing, and scarification, among others. Another such method, artificial dental modification, is found in many areas of the world but is perhaps best known in Mesoamerica. The Mayas were a peaceful people with a highly developed culture who inhabited the Yucatan Peninsula. The nation's history began about 2500 B.C., but the culture flourished from about 300 A.D. to about 900 A.D. In their dental practiced, teeth were filed into points, ground into rectangles and drilled with small holes to permit the insertion of small round pieces of stone in over a hundred different patterns 2. The filing procedure was employed using a hard tube that was spun between the hands or in a rope drill, with a slurry of powdered quartz in water as an abrasive, to cut a hole through the tooth enamel. Then, the inlay was cemented into place. The stone inlay was ground to fit the cavity so precisely and the plant adhesive was so powerful that many have remained in the teeth for thousands of years 2,3. Although many studies involve description and classification of artificially modified teeth, few examine the consequences of this modification. Previous X- ray and scanning electron microscopy analysis have shown that most of the time the holes reached the dentine and even the pulp cavity 2,4-6. However, to date no study demonstrated the three-dimensional relationship between the tooth inlay and the pulp cavity in Mayan's teeth. The aims of the present study were to evaluate qualitatively the relationship between the inlay and the pulp cavity, and its influence within the pulp canal space, in ancient Mayan's teeth, using microcomputed tomography technique.

2 Method Six well-preserved Mayan's teeth from Guatemala with approximately 1600 years old, donated by a private collector, presenting alteration of the labial surface of the crown with inlays of jade or hematite, classified as types E1 (one stone at the labial surface) and E2 (two stones at the labial surface) 7 were selected for this study. SkyScan 1074 (SkyScan, Kontich, Belgium) high-resolution micro-ct scanner was used to scan the teeth. The system consisted of a sealed air-cooled X-ray tube, kv / 40W / 800 µa, with a precision object manipulator with two translations and one rotation direction. The system also included a 14- bit CCD-camera based on a 1.3 Megapixel (1304 x 1024 pixels) CCD-sensor. Each tooth was vertically positioned on a metal holder in the center of the specimen stage and scanned (50 kv, 800 µa) with a pixel size of 22.5 µm, rotational step of 0.70 degree, rotational angle of 180 degrees, and a 3.1-second exposure time, using a 1-mm-thick aluminum filter. With the NRecon version (Skyscan) software, images obtained from the scan were reconstructed to show 2-dimensional (2D) slices of the inner structure of the teeth. Finally, the CTan version 1.11 and CTVol version 2.1 (Skyscan) softwares were used for the 3- dimensional (3D) volumetric visualization and qualitative analysis of the canal space assessed by an expert observer. Results The filing of the all analyzed teeth was of type E1 (Figures 1 to 5) except the lateral upper incisor that was type E2 (Figure 6). It is interesting to note that teeth with a thicker enamel layer, as canines and premolar (Figures 1 to 3), did not present significant alteration in the canal space, as pulp tissue was not injured. The interior anatomy of the root canal space and dentine are clearly visible in these teeth. On the other hand, the central and lateral incisors (Figures 4 to 6) showed that the cavities created to insert the inlay stones perforated the pulp chamber, resulting in an irreversible inflammatory reaction of pulp tissue leading to a massive internal resorption (Figures 4 and 5) and calcification of the pulp tissue (Figure 6). Figure 1: Right upper canine. 3D reconstruction in a frontal and lateral views of the external (a, b) and internal (c, d) anatomy of the teeth and the pulp canal space (e, f). Transversal (g, h) and axial (i, j, k) cut showing pulp canal space and dentine without evidence of disease [green arrow: dental inlay (hematite)].

3 Figure 2: Right upper first premolar. 3D reconstruction in a frontal and showing pulp canal space and dentine without evidence of disease [green arrow: dental inlay (jade)]. Figure 3: Right upper canine. 3D reconstruction in a frontal and lateral views of the external (a, b) and internal (c, d) anatomy of the teeth and the pulp canal space (e, f). Transversal (g, h) and axial (i, j, k) cut showing pulp canal space and dentine without evidence of disease [green arrow: dental inlay (jade)].

4 Figure 4: Left upper central incisor. 3D reconstruction in a frontal and arrow: internal resorption; green arrow: dental inlay (hematite)]. Figure 5: Left upper central incisor. 3D reconstruction in a frontal and arrow: internal resorption; green arrow: dental inlay (hematite)].

5 Conclusion Figure 6: Right upper lateral incisor. 3D reconstruction in a frontal and arrow: calcification; green arrow: dental inlay (jade)]. Considering the limitations of the present study, micro-ct analysis of ancient Mayan's teeth allowed to observe tridimensionally the anatomical relationship between the bottom of the artificial cavity prepared to hold an inlay, and the pulp chamber, evidencing a perforation of a depth of approximately 1.5 mm deep, with parallel walls and a convexly shaped basis only in the incisors. In these teeth, the pulpal response was readily detectable with the presence of internal resorption and calcification. References: 1. Hargreaves KM, Cohen S, "Cohen's Pathways of the Pulp", Mosby Elsevier, Whittington SL, Reed DM, "Bones of the Maya: Studies of Ancient Skeletons", University of Alabama Press, Romero-Vargas S, Ruiz-Sandoval JL, Sotomayor-González A, Revuelta-Gutiérrez R, Celis-López MA, Gómez-Amador JL, García-González U, López-Serna R, García- Navarro V, Mendez-Rosito D, Correa-Correa V, Gómez-Llata S, "A look at Mayan artificial cranial deformation practices: morphological and cultural aspects", Neurosurg Focus, 6, E2, Gwinnett AJ, Gorelick L, "Inlayed teeth of ancient Mayans: a tribological study using the SEM", Scan Electron Microsc, 2, , McKillop HI, "The ancient Maya: new perspectives", ABC-CLIO, González EL, Pérez BP, Sánchez JA, Acinas MM, "Dental aesthetics as an expression of culture and ritual", Brit Dent J, 2, 77-80, Romero J, "Dental Mutilation, Trephination, and Cranial Deformation", University of Texas Press, 1970.