A Case of Dental Fusion in Primary Dentition from Late Bronze Age Greece

10.2478/bjdm-2018-0018

E I

L BALKAN JOURNAL OF DENTAL MEDICINE A ISSN 2335-0245 IC G LO TO STOMA

SUMMARY Paraskevi Tritsaroli Background/Aim: Dental fusion is a developmental abnormality American School of Classical Studies at Athens, that can occur in primary and/or permanent dentition. Case report: A Greece 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. CASE REPORT (CR) Key words: Fused Teeth, Primary Dentition, Greece, Late Bronze Age Balk J Dent Med, 2018;102-105

Introduction populations several cases of fused teeth, primary or permanent, have been documented including either two or Double teeth are a developmental anomaly that three adjacent teeth or involving surnumerary teeth2-3,12-17. describes adjacent teeth joined by the dentin or pulp and Few examples of double teeth are included in the modern occur in two different ways: by gemination and by fusion1,2. clinical record in Greece18,19. In gemination, one tooth splits into two teeth while fused Tooth fusion is rare in archaeological populations and teeth are two separate teeth that have fused into one tooth. only a small number of cases are documented20-23. The aim Gemination and fusion may look virtually identical. of this report is to present a case of fusion of two adjacent Differential diagnosis between fusion and gemination primary teeth displayed by an infant from a Late Bronze Age is difficult to make especially if a supernumerary tooth is cemetery in central Macedonia and make this data available involved2-6. Differences between the frequency, distribution for comparative analysis. To our knowledge, this is the first and associated developmental anomalies suggest that fusion example reported from an archeological context in Greece. 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 Case Report affected in Japanese, Chinese and possibly Amerindian children7; this frequency shows little variation depending The case presented here came from the Late Bronze on the population sample examined7-11. In living Age (LBA) cemetery of Rema Xydias. The site was Balk J Dent Med, Vol 22, 2018 Dental Fusion 103 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 Figure 2. Lingual view of the fused incisors 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 Figure 3. Labial view of the mandible and the fused incisors 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 4. Apical view of the fused Figure 5. Radiograph of the fused incisors incisors, labial view

Figure 1. Radiograph of the preserved right (a) and left (b) parts of the In apical view, the teeth showed two roots fused mandible together with two distinct root canals (Figure 4). Radiographic examination confirmed that the teeth were Macroscopic examination revealed that the primary joined by the (confluent) dentin, they had separated pulp lower right central and lateral incisors were joined; they chambers and each tooth maintained its own root canal did not show mirror image of the coronal halves but they (Figure 5). Finally, the number of teeth in the dental arc was reduced because fused teeth were counted as one had ‘separate’ crowns and roots. Vertical labio-lingual unit. The development of the permanent dentition seemed grooves defined two distinct, coronal and root, segments unaffected and no extra or missing teeth were observed each one resembling a normal primary central and lateral macroscopically or radiographically according to the dental incisor shape respectively (Figures 2 & 3). age of the individual. No dental caries were recorded. 104 Paraskevi Tritsaroli Balk J Dent Med, Vol 22, 2018

Discussion macroscopic and radiographic examinations support the diagnosis of incomplete fusion rather than gemination; In their review of literature, Schuurs and van partial fusion suggests that the affected teeth fused later Loveren2 reported various diagnostic criteria for fusion in development, after the calcification stage and the and gemination including morphology, anatomy, location, formation of crowns6,28. Fused teeth are free of dental crowding and counting; in addition to radiography, Uӱs diseases and no other dental abnormalities are recorded. and Morris6 used also histology. In the present report, the Obviously, this unique case of fused incisors cannot be differential diagnosis was based on morphology, anatomy, used to make inferences on the genetic background of this location, tooth count and radiological examination. In infant nor the population from which it came. 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 Conclusions and root canal systems while in gemination there is only one root2,28,29. Finally, counting teeth can be useful to In sum, this report includes the first evidence differentiate between fusion and gemination (the double of double teeth in primary dentition reported from teeth are counted as one): if the dental arcade contains a archaeological context in Greece and one of the rare normal set of teeth, then the double teeth are recorded as examples of dental fusion in the bioarchaeological record. gemination. On the contrary, if the dental arc misses one Finally, this report adds further to the mapping of dental 30 tooth, then the double teeth are classified as fusion . anomalies in past populations. Dental fusion is a developmental anomaly that can occur in primary and/or permanent dentition. This Acknowledgements defect arises through the union of two or more normally The author wishes to thank the Institute of Aegean 28,29 separated tooth germs during odontogenesis . The Prehistory (INSTAP) for funding the analysis of human union of adjacent teeth, jointed by the dentin, may involve skeletal remains, the excavator Sophia Koulidou either the crown or the root or both of them. Fusing can be (Ephorate of Antiquities of Pieria) for providing complete or incomplete (partial) depending on time when archaeological information, and Anastasia Bania for the force causing the narrowing of the space between conserving human remains. Special thanks are also due 29 the tooth germs appeared during development . Fused to Dr. Dimitris Michailidis (The M.H. Wiener Laboratory teeth affect more frequently the primary than permanent for Archaeological Science, ASCSA) for x-ray analysis, dentition, they are found usually unilateral than bilateral, Professor Maria Liston (University of Waterloo) for mostly in the lower than upper dentition, and most helpful assistance and the anonymous reviewers for their commonly in the incisor and canine region2,7,14,29,31; substantial comments. 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 References influences and genetic predisposition. It is reported in the literature that the pressure or physical forces can 1. Hagman FT. Anomalies of form and number, fused primary produce close contact between two developing teeth; this teeth, a correlation of the dentitions. ASDC J Dent Child, contact causes the necrosis of the epithelial tissue that 1988;55:359-361. separates them and leads to their fusion. Other researchers 2. Schuurs AHB, van Loveren C. Double teeth: review of the suggest a relationship between fusion and fetal alcohol literature. ASDC J Dent Child, 2000;67:313-325. exposure, thalidomide embryopathy, hypervitaminosis A 3. Gurri FD, Balam G. Inheritance of Bilateral Fusion of the as well as a variety of syndromes3,11,14,29,32. Furthermore, Lower Central and Lateral Incisors: A Pedigree of a Maya heredity seems to have an important implication in the Family from Yucatan, Mexico. Dent Anthropol, 2006;19:29-34. development of this anomaly as evidenced in family 4. Nunes E, Moraes IG, Novaes PM, Sousa SMG. Bilateral and twin studies3,12,33. Fused teeth are vulnerable to Fusion of Mandibular Second Molars with Supernumerary be affected by caries in the groove dividing the bifid Teeth: Case Report. Braz Dent J, 2002;13:137-141. 5. Ntaoutidou S, Dermata A, Dimitraki D, Arapostathis crown, periodontal disease and spacing problems4,34,35. K. Dental fusion and gemination in primary dentition. Furthermore, fusion of primary teeth may be associated Paidodontia, 2016;30:67-75. with development disturbances in the permanent 6. Uÿs H, Morris D. ‘Double’ teeth – a diagnostic conundrum. successors such as microdontia, delayed tooth formation Dent Update, 2005; 32:237–239. 8,9,13,33,36,37 or even congenital absence of tooth . 7. Yonezu T, Hayashi Y, Sasaki J, Machida Y. Prevalence of The infant from Rema Xydias in Greece showed congenital dental anomalies of the deciduous dentition in double teeth with ‘separate’ crowns and roots. The Japanese children. Bull Tokyo Dent Coll, 1997;38:27-32. Balk J Dent Med, Vol 22, 2018 Dental Fusion 105

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