Findings from computed tomography examinations of Viking skulls

doi:10.21203/rs.3.rs-5187695/v1

Download PDF

Research

Findings from computed tomography examinations of Viking skulls

https://doi.org/10.21203/rs.3.rs-5187695/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Introduction

Computed tomography images can provide information about anatomical structures and pathological processes in ancient skulls. A previous study on the teeth and jaws of 171 individuals in a late Swedish Viking-age population, dating around the 10th − 12th century made clinical examinations that included intraoral radiographs. To gain more information about these unique remains, this study examined a subset of this population with computed tomography.

Materials and method

The skulls of 15 Viking-era individuals were examined with computed tomography. Two dental specialists in maxillofacial radiology and one general dentist examined the images together, performing the diagnostics.

Results

Findings included signs of pathological conditions of the teeth; of the alveolar, auricular, mandibular, and maxillary bone; and of the sinuses and temporomandibular joints. These findings indicated the presence of dental caries, periodontal disease, periapical destructions with and without communication to the maxillary sinus or the oral cavity, infection-induced periosteal bone deposition, remodelling of the caput mandibulae, infection located to the ramus mandibulae, and sinusitis.

Conclusion

Computed tomography investigation of skeletal remains from an early Christian community in the Viking era in Sweden found that the population suffered from numerous orofacial pathologies, including dental disease, sinusitis, otitis, and various infections. As an investigation method of skeletal remains, computed tomography imagery was able to identify pathologies that might be difficult to find through clinical examination.

Health sciences/Diseases/Oral diseases

Computed tomography

Dental anthropology

Oral health

Sweden

Viking era

Radiography

Traditional osteoarchaeological analysis of human remains comprises a clinical examination under a strong light source by an archaeologist with special competence in osteology. Dental examinations with a dental mirror and an explorer could be part of this examination. ¹ This examination is sometimes supplemented with various radiographic methods, two- (2D) and three-dimensional (3D), for deeper examination. ^{2, 3} 3D imaging using computed tomography (CT) has previously proven to be a valuable retrospective diagnostics tool in paleopathology. ³ It is a non-invasive technique for accessing information on anatomical structures located in inaccessible locations. ⁴

CT was introduced in 1971⁵, primarily for use in clinical medical applications, but has since proven useful in paleopathology. CT images are three dimensional, eliminating the problem of superimposed structures which occurs in conventional radiographic imaging. Use of such imagery in diagnostics, however, should be done by personnel with special training and competence so that information is correctly interpreted.

Dating from the 10th − 12th century AD, and excavated in 2005 on the grounds to the rear of Varnhem Abbey, in Skara municipality, Västergötland County, Sweden, this Viking population of Varnhem represents one of the earliest Christian settlements in Sweden (Fig. 1). ⁶ The skeletal and dental remains are well-preserved due to the high mineral content of the tissues ¹ and the excellent preservational environment of the local burial grounds. The remains are thus well suited for osteological analysis. Around 300 of these individuals have undergone osteologic analysis. ⁷ The jaws and teeth of these individuals were thoroughly examined, giving valuable insights to life during the Viking era. ⁸. Odontological findings such as dental caries, infections, and other maxillofacial pathologies can provide knowledge about the life of our ancestors. ¹

This study used CT imaging to examine orofacial pathological conditions in Viking-age remains from Varnhem, Sweden.

Study population

Of the 171 partial and complete dentitions that previously had undergone odontological analysis⁸, 15 were chosen for a CT examination. One author (CB) selected the dentitions based on the following inclusion criteria: (1) cranium with or without mandible and (2) possible to mount in the CT scanner. The exclusion criteria were (1) lack of a cranium with maxillae and (2) not possible to mount in the CT scanner. An osteologist (MV) had already estimated age and sex according to Buikstra & Ubelaker. ⁹ The study population comprised 15 individuals, of which nine were male, and six, female. The osteologist determined age at death as ranging from 24 to 60 years.

Radiographic examination

The CT examination was done using the Optima^™ CT660 (GE Healthcare, Sweden AB). A helical scan (0.625 mm slice thickness and interval) of the cranium was made with a field of view (FOV) of 160 mm, and exposure parameters of 80 kV and 50 mA. After examination, an axial stack of images was exported in Digital Imaging and Communications in Medicine (DICOM) format to a medical picture archiving and communication system (PACS; Sectra IDS7; Sectra AB, Linköping, Sweden) for subsequent viewing and interpretation on a high-resolution computer screen. Three dentists, of which two were specialists in dentomaxillofacial radiology (EB + HL), and one general dentist (CB) viewed, recorded and performed the diagnostics together. Figure 2 illustrates the mounting of a skull in the CT-scanner.

Statistical work

Findings are presented as descriptive statistics.

Additional information

The current study is a part of an archaeological examination approved by the County

Administrative Board in Västra Götaland (Länsstyrelsen Västra Götaland). In compliance with relevant regulations, no additional permits were needed. The remains that were part of this study are located at Västergötlands Museum, Stadsträdgården, Skara, Sweden.

Indications of several pathologies were found in present study: infection-induced periosteal bone growth, sinusitis, dental caries, periodontal disease, remodelling of caput mandibulae, infection located in the ramus mandibulae, and periapical destructions with and without communication to the sinus maxillaris. Figures 3 and 4 describe the results of the CT imaging. Figure 5-9 illustrates some of the findings. Findings included radiographic signs of pathology of the temporomandibular joints (TMJ), the mandibular and maxillary bones, the sinuses, the teeth and alveolar bones, and the auricular bones.

Lost teeth

All individuals except two (297, 64) had lost teeth post mortem (PM; range 1–22 teeth). During mounting of the skulls in the CT, some teeth were not retained in the alveoli and, thus, not included in imaging (referred to as “lost PM” in this study). Six individuals suffered from ante mortem (AM) tooth loss, including one completely edentulous individual (64), and one individual with an edentulous maxilla (181). The number of teeth lost AM ranged from 1 to 32 per individual.

Periodontal disease

Radiographic findings of periodontal disease were common in the studied subjects. The findings included horizontal bone loss, vertical bone defects and furcation involvement in two-thirds of the study cohort (10/15 individuals). This was most prevalent in the posterior region, especially in the molars, but the anterior teeth of some individuals had also been affected.

Periapical inflammatory disease

Signs of periapical inflammatory disease were found in 80% (12/15) of the individuals. The only cohort members without signs of periapical inflammatory disease were individuals 114, 204, and 218. Individual 218 was almost completely edentulous. In several cases, the bony borders of the lesions were perforated, creating communication with either the maxillary sinus (individuals 12 and 299), or the oral cavity (individuals 12, 102, 114, 126, 181, 233, and 64). In one case (12) a lesion had diffuse borders. One case of a cyst-like lesion was found (tooth 36, individual 12).

Temporomandibular joint abnormalities

Findings of abnormalities of the TMJ were common. These findings included osteophyte formation (individual 12), flattening of the condyle (62 and 144), loss of cortical border (126, 181, and 299), flattening of the articulating eminence (62), destruction zones of varying magnitudes (62, 218, and 299), sclerotization of the bone in the ramus mandibulae (218) and periosteal bone reaction (299). In total, over half of the study cohort (8/15) displayed some variation of TMJ abnormalities.

Other findings

Other signs of pathological conditions were found, such as carious lesions (individuals 126, 144, 204, 297), retained roots (233), alveolar bone destruction (181, 218), resorption of the alveolar crest (126), periosteal bone formation of the alveolar process (98), signs of extensive infection in ramus mandibulae (218), bone defects (62, 233), broadened peripheral cortex of the facial and/or maxillary sinus in concordance with chronic sinusitis (62, 181, 126), sclerotization of the mastoid process (12), and destruction of bone towards the left external acoustic meatus (299).

Additional findings in this cohort included anatomical variations such as a three-rooted premolar (tooth 24, individual 204), tori palatini (individual 12), and PM conditions such as PM fractures. In several individuals (102, 218, 233), debris trapped in the skull cavities and obscuring the bony structures made interpretation of the images of these segments difficult. Dentine tissue of two molars (teeth 36, 37) from one individual (62) had been sampled PM, thus, causing PM defects.

In this study, radiographic 3D imaging provided novel information about the health of 15 Varnhem Vikings. In light of modern medicine and dentistry, this unique information increases our understanding of life in Viking-era Varnhem. The findings indicate that the Vikings in this early Christian community suffered from numerous orofacial pathologies, including sinusitis, otitis, and infection. Many of these illnesses are highly relatable and give a rare insight into the sufferings of these Vikings. Some of the most important findings are those indicating infections. In a time when antibiotics, or other modern treatment, were unavailable, these conditions must have been highly challenging. Some infections may have led to death through spreading or sepsis.

In one individual (12), an osteophyte was located on the anterior surface of the right condyle. Osteophytes are bony outgrowths covered in cartilage, forming at the surface of the articulating bone as a response to arthritic conditions, such as rheumatoid arthritis and osteoarthritis. ¹⁰ They are a hallmark radiographic feature of degenerative disease of the TMJ, so it is probable that individual 12 suffered from this condition. In other individuals, other signs of degenerative joint disease were noted including erosion and flattening of the condyle, flattening of the articulating eminence, and destruction zones. Radiographic indications of pathological processes were clearly prevalent in this study cohort.

Most of the studied remains (12/15 or 80%) displayed signs of periapical inflammatory disease (apical periodontitis). Such pathology could arise from tissue necrosis, a condition caused by inflammatory responses to bacterial invasion of the root canal. Sources of bacterial invasion include dental caries, attrition, and trauma. ¹¹ An earlier study on Viking-age remains from the same population as the present study cohort found high prevalences of dental caries and attrition. ⁸ Periapical inflammatory disease is not self-healing, and a well-known coeval treatment for these Viking-time individuals was tooth extraction. However, besides extraction, the above study ⁸ also observed signs of other treatment procedures, such as creating a coronal opening to the pulpal chamber. Untreated lesions might be non-symptomatic, but they can cause pain and intra- or extraoral swelling, and less commonly, infection, airway obstruction, and sepsis, which can be fatal without treatment. Two members of our cohort (12, 299) had lesions that either had perforated their bony borders and created communication with the maxillary sinus, or displayed a diffuse border towards the same sinus. Another individual (62) exhibited AM loss of tooth 28 with residual bone destruction and communication with the sinus maxillaris, which could result in sinusitis. Additionally, three individuals (62, 181, 126) in our study cohort had a broadened peripheral cortex of the facial and/or maxillary sinus, which indicates chronic sinusitis. Thus, several cohort members suffered from signs of untreated sinusitis. Well-known symptoms of this condition include nasal obstruction, sensation of facial pressure or fullness, nasal discharge and olfactory loss ¹², which might have caused difficulties for the affected individuals.

One individual (12) displayed a sclerotization of the mastoid process. These findings can be seen in individuals with acute or chronic otitis media ^{13, 14}. In the acute phase, otitis media may spread from the ear to the mastoid bone ¹⁵ causing an infection. Today mastoiditis is treatable, but before the advent of antibiotics, mastoiditis was a cause of death amongst children. ¹⁵ The individual displaying this pathology, however, was female and 45–60 years old at the time of death. The CT image of another individual (299), also female and 25–34 years of age at the time of death, revealed a destruction of the temporal bone towards the left external acoustic meatus.

One individual (98) showed signs of a periosteal reaction in the form of bone formation of the alveolar process. This is a radiographic sign of a nonspecific response of the periosteum to irritants or stimuli, such as trauma, arthritis, malignancies, inflammation, and infections, including osteomyelitis. ¹⁶

Due to the small sample size, the uneven distribution between males (n = 9) and females (n = 6), and the limited number of remains suitable for this investigation, no conclusions regarding sex differences could be drawn. The entire population, of which the remains in our study are a part, also exhibited a discrepancy in sex ratio. The excavation site mostly comprises the southern grounds of the graveyard, which may explain this. In line with early Christian customs, males were buried south of and females, north of the church. ⁶ Unfortunately, the fragmented state of many of the remains prohibited the use of radiographic imaging. Additionally, the extent of PM tooth loss is a source of bias, mostly for determining dental pathologies.

Most Swedish Vikings, including the Varnhem population, lived in farm-based communities. ¹⁷ The individuals in our study cohort were previously clinically examined, both osteologically and dentally. ⁶ However, the present study has added to our knowledge of the health and ill-health of the Varnhem Vikings.

As an investigation method of skeletal remains, computed tomography imagery was able to identify pathologies that might be difficult to find through clinical examination. This is in parity with the findings of studies on other archaeological remains. ¹⁸

The findings of the present study provide rare insights into early Christian life in a Swedish Viking settlement, including potential life-threatening infections in a time where no treatment was available.

Ethics declaration

No ethical approval was needed according to the Swedish laws and regulations regarding archaeological remains. The County Administrative Board (Länsstyrelsen Västra Götaland) approved the current archaeological examination. No further ethical approval was needed since the odontological examination of these archaeological remains was part of an osteological/archaeological examination carried out by Västergötlands museum (the institute in charge) in accordance with relevant guidelines.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Author contributions

Carolina Bertilsson conceived the study. Maria Vretemark prepared the samples. Henrik Lund, Eva Borg and Carolina Bertilsson designed the protocol, performed the examinations, contributed to data collection and preparation, and analysed the data. Carolina Bertilsson, Eva Borg and Henrik Lund wrote the manuscript and contributed to the interpretation of the results. Maria Vretemark, Carolina Bertilsson, Eva Borg and Henrik Lund were all responsible for critical revision of the article and approval of the final version.

Acknowledgements

The authors thank the Specialist Clinic for Oral &Maxillofacial Radiology, the Public Dental Service (Folktandvården), Västra Götaland, Sweden, for supporting this study by providing access to the CT. We also thank Västergötlands museum, Skara, Sweden, for access to the study material.

Hillson S. Recording dental caries in archaeological human remains. International journal of osteoarchaeology 2001, 11(4): 249-289.
Lucas S, Sevin A, Passarius O, Esclassan R, Crubezy E, Grimoud AM. Study of dental caries and periapical lesions in a mediaeval population of the southwest France: differences in visual and radiographic inspections. Homo 2010, 61(5): 359-372.
Coqueugniot H, Dutailly B, Dutour O. The third dimension in palaeopathology: How can three‐dimensional imaging by computed tomography bring an added value to retrospective diagnosis? International journal of osteoarchaeology 2020, 30(4): 538-550.
Uldin T. Virtual anthropology - a brief review of the literature and history of computed tomography. Forensic Sci Res 2017, 2(4): 165-173.
Schulz RA, Stein JA, Pelc NJ. How CT happened: the early development of medical computed tomography. J Med Imaging (Bellingham) 2021, 8(5): 052110.
Vretemark M, Axelsson T. The Varnhem Archaeological Research Project: A New Insight into the Christianization of Västergötland. Viking and medieval Scandinavia 2008, 2008(4): 209-219.
Vretemark M. Aristocratic farms and private churches in the surroundings of Skara in Västergötland – some examples from the 11th to 13th century. The proceedings of the symposium The Buildings of Medieval Reykholt: the Wider Context, in Reykholt on Iceland, the 18th and 19th of October 2013; 2017.
Bertilsson C, Vretemark M, Lund H, Lingström P. Caries prevalence and other dental pathological conditions in Vikings from Varnhem, Sweden. PloS one 2023, 18(12): e0295282-e0295282.
Skinner M. Standards for Data Collection from Human Skeletal Remains. Jane E. Buikstra , Douglas H. Ubelaker. The Quarterly review of biology 1995, 70(4): 539-540.
Isberg A. Temporomandibular joint dysfunction : a practitioner's guide. London : Isis Medical Media: London, 2001.
Kakehashi S, Stanley HR, Fitzgerald RJ. The effects of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surg Oral Med Oral Pathol 1965, 20: 340-349.
Rudmik L, Soler ZM. Medical Therapies for Adult Chronic Sinusitis: A Systematic Review. JAMA 2015, 314(9): 926-939.
Bernatz S, Mahmoudi S, Martin SS, Burck I, Vogl TJ, Ackermann J, et al. Differences in mastoid and middle-ear cavity opacification in CT between intensive care patients and patients with acute mastoiditis requiring surgical treatment. Eur J Radiol Open 2021, 8: 100365.
Lee DH, Jun BC, Park JO, Yeo SW. Magnetic resonance imaging of the mastoid cavity and middle ear: prevalence and clinical significance of incidental abnormal findings in a nonotolaryngologic adult and pediatric population. J Otolaryngol 2006, 35(1): 13-18.
Cassano P, Ciprandi G, Passali D. Acute mastoiditis in children. Acta Biomed 2020, 91(1-s): 54-59.
Potter RbBJ. Oral Radiology: Principles and Interpretation by Stuart White and Michael Pharoah. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology 2005, 99(2): 253-253.
Ahlström Arcini C. The Viking Age : a time of many faces. Oxford : Oxbow Books, 2018.
Garvin HM, Stock MK. The Utility of Advanced Imaging in Forensic Anthropology. Academic Forensic Pathology 2016, 6(3): 499-516.

There is no duality of interest

S1table1.pdf
S1 Table: Findings of the computed tomography images. Samples, description and raw data. S1 presents the identities, biological markers, and pathological conditions of the study cohort.

Download PDF

Version 1

posted

You are reading this latest preprint version

Findings from computed tomography examinations of Viking skulls

Status:

Version 1

Abstract

Figures

Introduction

Materials and methods

Results

Discussion

Conclusion

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1