A case of dental fusion in primary dentition from Late Bronze Age Greece
Tritsaroli, Paraskevi
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Balkan Journal of Dental Medicine DOI:
10.2478/bjdm-2018-0018
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Publication date: 2018
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Tritsaroli, P. (2018). A case of dental fusion in primary dentition from Late Bronze Age Greece. Balkan Journal of Dental Medicine, 22(2), 102-105. https://doi.org/10.2478/bjdm-2018-0018
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SUMMARY
Background/Aim: Dental fusion is a developmental abnormality that can occur in primary and/or permanent dentition. Case report: A case of double primary teeth from a Late Bronze Age cemetery in Greece is presented. Age estimation of the skeleton was based on dental eruption and development as well as on fusion of primary ossification centres of the cranial and post-cranial skeleton. Analysis of double teeth used morphology, anatomy, location, tooth count and radiological examination. Results showed a 18 month infant. Primary lower right central and lateral incisors were joined by the dentin, and they had distinct crowns and separated pulp chambers; each tooth maintained its own root canal and resembled a normal primary central and lateral incisor shape respectively. Diagnosis showed that double teeth were the result of partial fusion rather than gemination. No other dental abnormalities or lesions were recorded and subsequent teeth were not affected. Conclusions: This is the first example of double teeth in primary dentition reported in the literature from archaeological assemblages in Greece. Being one of the rare examples of dental fusion in the bioarchaeological record, this report adds further to the mapping of dental anomalies in past populations.
Key words: Fused Teeth, Primary Dentition, Greece, Late Bronze Age
Paraskevi Tritsaroli
American School of Classical Studies at Athens, Greece
CASE REPORT (CR)
Balk J Dent Med, 2018;102-105
BALKAN JOURNAL OF DENTAL MEDICINE ISSN 2335-0245
A Case of Dental Fusion in Primary Dentition from
Late Bronze Age Greece
STOMATO LOGI CA L S O CIE T Y
Introduction
Double teeth are a developmental anomaly that describes adjacent teeth joined by the dentin or pulp and occur in two different ways: by gemination and by fusion1,2. In gemination, one tooth splits into two teeth while fused teeth are two separate teeth that have fused into one tooth. Gemination and fusion may look virtually identical. Differential diagnosis between fusion and gemination is difficult to make especially if a supernumerary tooth is involved2-6. Differences between the frequency, distribution and associated developmental anomalies suggest that fusion and gemination result from independent mechanisms and probably have different genetic control3.
Double teeth affect less than 1% of children among Caucasians6 while 2.8% of primary dentitions would be affected in Japanese, Chinese and possibly Amerindian children7; this frequency shows little variation depending on the population sample examined7-11. In living
populations several cases of fused teeth, primary or permanent, have been documented including either two or three adjacent teeth or involving surnumerary teeth2-3,12-17. Few examples of double teeth are included in the modern clinical record in Greece18,19.
Tooth fusion is rare in archaeological populations and only a small number of cases are documented20-23. The aim of this report is to present a case of fusion of two adjacent primary teeth displayed by an infant from a Late Bronze Age cemetery in central Macedonia and make this data available for comparative analysis. To our knowledge, this is the first example reported from an archeological context in Greece.
Case Report
The case presented here came from the Late Bronze Age (LBA) cemetery of Rema Xydias. The site was
Figure 2. Lingual view of the fused incisors located on the foothills of Mount Olympus in southern
Pieria, in close proximity to the modern village of Platamonas. The excavation at Rema Xydias was carried out in 2014 and revealed a LBA settlement and cemetery (1400-1100 BCE); the cemetery was one of the very few and richly furnished LBA cemeteries in Northern Greece and it testified the presence of the Mycenaean civilization at the southern border of central Macedonia (Koulidou, unpublished data). The Minimum Number of Individuals (MNI) of the sample was 45. Cist Grave 18 revealed a double burial including an infant skeleton in primary position (skeleton 18.1) and the disturbed primary burial of a child (skeleton 18.2); the double teeth were recorded on skeleton 18.1.
Human skeletal remains were analyzed at the Malcolm H. Wiener Laboratory for Archaeological Science (ASCSA) in 2016. Analysis used the methods outlined in Buikstra and Ubelaker for complete skeletons24. Age estimation for subadults was based on dental eruption and development25 and it was assisted by radiography in order to take into account teeth buds in the alveolar bone; age estimation also considered fusion of primary ossification centres of the cranial and post-cranial skeleton26. Similarly, double teeth were analyzed macroscopically under normal light conditions and radiographically.
Age-at-death of skeleton 18.1 was estimated at 18m±6months; no attempt was made to estimate the sex of this infant from its bones because methods published for sexing infant skeletons are either not fully validated or have low accuracy26,27. Fourteen primary teeth and eight permanent teeth buds were preserved (the fused teeth were counted as one). The maxilla was poorly preserved and ten maxillary teeth and teeth buds were recorded without their alveolar bone. On the contrary, the mandible was almost complete; all preserved primary teeth were erupted except both primary second molars and permanent first molars’ buds that were in the alveolar bone (Figures 1a & b).
Figure 1. Radiograph of the preserved right (a) and left (b) parts of the mandible
Macroscopic examination revealed that the primary lower right central and lateral incisors were joined; they did not show mirror image of the coronal halves but they had ‘separate’ crowns and roots. Vertical labio-lingual grooves defined two distinct, coronal and root, segments each one resembling a normal primary central and lateral incisor shape respectively (Figures 2 & 3).
Figure 3. Labial view of the mandible and the fused incisors
Figure 4. Apical view of the fused
incisors Figure 5. Radiograph of the fused incisors, labial view In apical view, the teeth showed two roots fused together with two distinct root canals (Figure 4). Radiographic examination confirmed that the teeth were joined by the (confluent) dentin, they had separated pulp chambers and each tooth maintained its own root canal (Figure 5). Finally, the number of teeth in the dental arc was reduced because fused teeth were counted as one unit. The development of the permanent dentition seemed unaffected and no extra or missing teeth were observed macroscopically or radiographically according to the dental age of the individual. No dental caries were recorded.
104 Paraskevi Tritsaroli Balk J Dent Med, Vol 22, 2018 macroscopic and radiographic examinations support the diagnosis of incomplete fusion rather than gemination; partial fusion suggests that the affected teeth fused later in development, after the calcification stage and the formation of crowns6,28. Fused teeth are free of dental diseases and no other dental abnormalities are recorded. Obviously, this unique case of fused incisors cannot be used to make inferences on the genetic background of this infant nor the population from which it came.
Conclusions
In sum, this report includes the first evidence of double teeth in primary dentition reported from archaeological context in Greece and one of the rare examples of dental fusion in the bioarchaeological record. Finally, this report adds further to the mapping of dental anomalies in past populations.
Acknowledgements
The author wishes to thank the Institute of Aegean Prehistory (INSTAP) for funding the analysis of human skeletal remains, the excavator Sophia Koulidou (Ephorate of Antiquities of Pieria) for providing archaeological information, and Anastasia Bania for conserving human remains. Special thanks are also due to Dr. Dimitris Michailidis (The M.H. Wiener Laboratory for Archaeological Science, ASCSA) for x-ray analysis, Professor Maria Liston (University of Waterloo) for helpful assistance and the anonymous reviewers for their substantial comments.
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Discussion
In their review of literature, Schuurs and van Loveren2 reported various diagnostic criteria for fusion and gemination including morphology, anatomy, location, crowding and counting; in addition to radiography, Uӱs and Morris6 used also histology. In the present report, the differential diagnosis was based on morphology, anatomy, location, tooth count and radiological examination. In general, fusion usually shows differences in the two halves of the joined crown while in gemination these are often mirror images. In addition, fused teeth have two distinct pulp chambers and two discernable roots and root canal systems while in gemination there is only one root2,28,29. Finally, counting teeth can be useful to differentiate between fusion and gemination (the double teeth are counted as one): if the dental arcade contains a normal set of teeth, then the double teeth are recorded as gemination. On the contrary, if the dental arc misses one tooth, then the double teeth are classified as fusion30.
Dental fusion is a developmental anomaly that can occur in primary and/or permanent dentition. This defect arises through the union of two or more normally separated tooth germs during odontogenesis28,29. The union of adjacent teeth, jointed by the dentin, may involve either the crown or the root or both of them. Fusing can be complete or incomplete (partial) depending on time when the force causing the narrowing of the space between the tooth germs appeared during development29. Fused teeth affect more frequently the primary than permanent dentition, they are found usually unilateral than bilateral, mostly in the lower than upper dentition, and most commonly in the incisor and canine region2,7,14,29,31; epidemiological studies have shown that both genders are equally affected2.
The causative factors of this anomaly remain unknown but could be the interplay of environmental influences and genetic predisposition. It is reported in the literature that the pressure or physical forces can produce close contact between two developing teeth; this contact causes the necrosis of the epithelial tissue that separates them and leads to their fusion. Other researchers suggest a relationship between fusion and fetal alcohol exposure, thalidomide embryopathy, hypervitaminosis A as well as a variety of syndromes3,11,14,29,32. Furthermore, heredity seems to have an important implication in the development of this anomaly as evidenced in family and twin studies3,12,33. Fused teeth are vulnerable to be affected by caries in the groove dividing the bifid crown, periodontal disease and spacing problems4,34,35. Furthermore, fusion of primary teeth may be associated with development disturbances in the permanent successors such as microdontia, delayed tooth formation or even congenital absence of tooth8,9,13,33,36,37.
The infant from Rema Xydias in Greece showed double teeth with ‘separate’ crowns and roots. The
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Received on June 20, 2017. Revised on August 19, 2017. Accepted on October 2, 2017. Correspondence:
Paraskevi Tritsaroli
The Malcolm H. Wiener Laboratory for Archaeological Science American School of Classical Studies, Athens, Greece e-mail: voula_tritsaroli@hotmail.com
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