3 Dental Anthropology 2022 │ Volume 35│ Issue 01 A Contextualized Enamel Growth Rate and Thickness Data Set Collected from British Populations Spanning the Past 2,000 Years Christopher Aris 1,2 * 1 Human Osteology Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK 2 Department of Applied Science, Wrexham Glyndwr University, Wrexham, UK The microscopic study of modern human perma- nent enamel has commonly analysed both enamel thickness (e.g., Macho & Berner, 1993; Reid and Dean, 2006; Suwa & Kono, 2005; Smith et al., 2006a, 2006b; Aris et al., 2020b) and daily secretion rates (DSRs; e.g., Beynon et al., 1991a; Lacruz & Bro- mage, 2006; Mahoney, 2008; Aris et al., 2020a; 2020b; Aris and Street, 2021). Both enamel thick- ness and DSRs have multiple component parts re- quired for their reconstruction and analysis. For enamel thickness these include dentine area, enam- el cap area, and enamel dentine junction length; and for DSRs include pre-averaged regional secre- tion rates collected across the enamel cap (e.g., Aris et al., 2020b). The complexity of these features of human enamel has allowed their subsequent anal- ysis to be broad, but to date these have been incon- sistent in coverage in terms of tooth type and enamel feature. For example, permanent molars have been widely analysed for their thickness (e.g., Schwartz, 2000; Suwa and Kono, 2005; Smith et al., 2006a, 2006b; Olejniczak, Smith, Feeney, Machiarel- li, Mazurier, Bondioli, and Radovčić, 2008; Ma- honey, 2010; Aris et al., 2020b) and cuspal DSRs (e.g., Beynon et al., 1991a; Lacruz and Bromage, 2006; Smith et al., 2007; Mahoney, 2008; Aris et al., 2020b). Conversely the study of permanent incisors and canines has seen very limited research for DSRs (FitzGerald, 1998; Reid, Benyon, and Ramirez Rozzi., 1998; Schwartz, Reid, and Dean, 2001; Aris et al., 2020a; Aris and Street, 2021) or for thickness outside of 3D analyses (e.g., Kono, Suwa, and Tanijiri, 2002; Kono and Suwa, 2008; Smith et al., 2012; Buti, LaCabec, Panetta, Tripodi, Salva- dori, Hublin, and Benazzi, 2017). The study of lat- eral molar DSRs has been similarly limited (Beynon et al., 1991a; Lacruz and Bromage, 2006; Aris et al., 2020b). In addition to the disproportionate use of micro- scopic enamel features across tooth types, outside of a select few examples, large data sets for perma- ABSTRACT This article represents an open repository of human enamel data collected/reconstructed from seven populations covering a 2,000 year time period in Britain via five temporally distinct periods. In total, data were collected from 285 permanent teeth, including maxillary and mandibular first molars, and maxillary canines and first incisors. Data were gathered through thin histological methods using standard procedures for sectioning human dental material. In regards to enamel growth, data is collect- ed for daily secretion rates (DSRs) for the inner, mid, and outer areas of lateral and cuspal enamel. For enamel thickness average (AET) and relative (RET) enamel thickness, cuspal linear thickness (CT), and lateral linear thickness (LT) was collected. Alongside the data presented, this article also provides clear and transparent explanations for all the methods involved in its production, in order to ensure under- standing of the rigorous protocol and consistency associated with the data provided. The novel data is also contextualised with a compilation of equivalent data published in past articles. *Correspondence to: Christopher Aris University of Kent Wrexham Glyndwr University Email: christopher.aris@glyndwr.ac.uk Keywords: enamel thickness, daily secretion rates 4 Dental Anthropology 2022 │ Volume 35│ Issue 01 nent enamel features have not been presented or made openly accessible (e.g., Reid and Dean, 2006; Smith et al., 2006a). Furthermore, in the cases where developmental enamel variables are made available, outside of a few exceptions (e.g., Kono et al., 2002; Grine, 2004; Reid and Dean, 2006; Ma- honey, 2010; Le Luyer et al., 2014; Buti et al., 2017), they are most frequently reported for single popu- lations/samples. Moreover, such variables are also typically reported as averages for groups. Where individual-level enamel data has been reported, it has only concerned enamel thickness, and one sin- gle human sample (Kono et al., 2002; Skinner et al., 2015; Lockey et al., 2020). These single human sam- ples were also generated as a comparative sample for equivalent hominin/hominoid data analysis, rather than in direct analysis of human enamel growth/morphological patterns. There is therefore a clear need for the further generation of develop- mental enamel variable data from multiple modern human populations, in order for intra-specific re- search of human dentition to continue – a topic that has seen a resurgence in recent years (e.g., Le Luyer, Rottier, and Bayle, 2014; Aris et al., 2020a, 2020b; Aris and Street 2021). Since the pioneering of enamel thickness re- search involving human samples (e.g., Molnar and Gantt, 1977; Martin, 1983, 1985), a great deal of re- search has involved 2D sections of teeth. An area where enamel research has developed over time, and also been less restrictive, is within 3D analysis of anterior teeth (e.g., Feeney, Zermeno, Reid, Nakashima, Sano, Bahar, and Smith, 2010; Smith et al., 2012; Buti et al., 2017) and molars (e.g., Kono- Takeuchi, Suwa, Kanazawa, and Tanijiri, 1997; Kono et al., 2002; Smith et al., 2006a; Kono and Su- wa, 2008). These 3D-based studies have involved inter-species hominin analyses, as well as also de- veloping the methodological approaches for intra- specific human enamel thickness analysis. Moreo- ver, genetic analyses have also begun to emerge within the ongoing research of human enamel, which have made substantial strides to explaining inter-species enamel thickness differences within the human phylogeny (e.g., Horvath et al., 2014, Ungar and Hlusko, 2016). While possessing a clear utility, these lines of research do not directly or fully address all the issues discussed so far. They do however help show the importance of contin- ued and nuanced research of human enamel. This therefore highlights the utility of providing more open access to relevant enamel thickness data. Alongside the areas of inequality in research coverage and data availability regarding micro- scopic features of human enamel, there is a grow- ing trend in intraspecific analyses investigating whether enamel growth and thickness has varied within the human species over relatively short pe- riods of time. To date, these analyses have found significant variations in both enamel thickness and regional DSRs between geographically similar populations differing in context by as little as 400 years (Aris et al., 2020a; 2020b). This varies from older research in the field which frequently has either pooled dental samples for their growth and thickness data, or just used a single sample popula- tion, in order to create representative data sets for geographic regions or the entire human species (e.g., Beynon et al., 1991b; Lacruz and Bromage, 2006; Smith et al., 2007; Mahoney, 2008). While not all past research has pooled human populations (e.g., Grine, 2004; Reid and Dean, 2006), the preva- lence towards doing so has meant that more recent research looking into whether the pooling of sam- ples from different populations has been forced to create completely new histological sample collec- tions to conduct their analyses. In these more re- cent analyses the use of comparative data sets from the pooled representative samples are limited in their utility (e.g., Aris et al., 2020b). In addition, while the production of new samples is useful to the field of dental anthropology, its destructive nature should be considered and pre-existing ma- terial used where possible and appropriate to help preserve dental remains wherever possible (Aris, 2020). This article aims to address the above issues by providing a large and freely accessible data set for researchers to use in analysis of both enamel thick- ness and enamel growth, via DSR measures across multiple tooth types and for multiple (five) mod- ern human populations, further presented along- side a guide for pre-existing equivalent data. The novel data sets will compromise individual-level data for individuals, as well as regional-level enamel measurements. Data of this type to date has not been reported or made available to this degree, with particular limitations existing regard- ing enamel growth data. The aim is that through this level of accessibility to this detailed a level of data, future research can more easily branch into the less well-covered features of enamel in current literature, and that further intraspecific research on modern humans can be conducted more easily. This will also represent the first data set regarding anterior tooth type enamel thickness accessible in this way. Finally, it is hoped that the open access publication of this data will help expand the analy- 5 Dental Anthropology 2022 │ Volume 35│ Issue 01 sis of enamel data gathered at the microscopic level to institutions unable to directly support histologi- cal and/or micro-CT methods. Material and Methods Dental sample To produce this repository, histological analysis was conducted on 285 permanent teeth collected from seven populations across five temporally dis- tinct periods: Roman (70-400AD), Early Pre- Medieval (500-600AD), Late Pre-Medieval (800- 1200AD), Medieval (1000-1600), and modern-day clinical material (extracted within the last 20 years; Table 1). All archaeological samples came from British excavations and modern-day samples com- promised teeth extracted from England and South- ern Scotland. Sex was estimated where possible from skeletal elements of the archaeological indi- viduals and known for a number of the modern- day samples. Details on known-sex/sex estima- tions are listed at the individual-level in the data sets, but a summary of the number of male and female individuals identified for each tooth type and population in provided in Table 2. Table 1. Descriptive information of dental samples for each population and tooth type. Population Date Location Collection Name Number of teeth sampled Upper incisors Upper Canines First Molars All com- bined 70-~2000AD England and Scotland N/A 81 69 115 Roman 70-400AD Cirencester, Gloucester St James’ Place/ Bath Gate 10 11 11 Early Pre- Medieval 500-600AD Ramsgate, Kent Ozengell 22 20 20 Late Pre- Medieval 800-1200AD Newcastle-Upon- Tyne, Northumberland Black Gate 10 10 21 Medieval 1100-1500AD Canterbury, Kent St Gregory’s Priory 19 8 43 1000-1600AD York, North Yorkshire Fishergate House 8 8 5 Modern- day Extracted within the last 20 years Newcastle-Upon- Tyne and Glas- gow UCL/Kent 12 12 15 Table 2. Descriptive information regarding the number of individuals across populations and tooth types with known-sex/sex estimations. Population Number of male individuals Number of female individuals Upper incisors Upper canines First molars Upper incisors Upper canines First molars Known sex Modern-day 5 9 4 7 3 5 Estimated sex Early Pre-Medieval 5 4 2 6 7 7 Late Pre-Medieval 1 5 0 1 2 1 Medieval 3 4 1 3 3 0 Roman 2 5 6 3 4 1 6 Dental Anthropology 2022 │ Volume 35│ Issue 01 Unworn teeth were selected where possible. When worn, only teeth with approximately 80% of their crown height remaining were selected based on criteria outlined by Guatelli-Steinberg and col- leagues (2005), and when wear was present no data relating to the cuspal region of the enamel cap was collected (Figure 1). One tooth was taken from each individual during the sampling process, following the guidelines for destructive sampling of human remains guideline outlined by Mays and col- leagues (2013) and on request from the institutions which curated the dental material utilised (see acknowledgements). Left teeth were utilised wher- ever possible, with the right tooth only being used in instances where the left was missing, poorly pre- served, or heavily damaged (data files note wheth- er left or right were analysed). Selection preference was also given to individuals presenting an anti- mere to the tooth being selected for sectioning. Ancestry was unknown for all individuals across all populations from which samples were taken. In the case of the archaeological collections this was due to individual records not existing for any of the individuals of any of the populations studied. For the modern-day individuals, due to GDPR data laws (specifically those limiting the storage and dissemination of special data relating to an individual’s personal identity) the only infor- mation available was the biological sex and town/ city location from which the individual had the tooth sampled extracted. Roman samples The Roman samples were from two similarly locat- ed sites in Cirencester: St James’ Place and Bath Gate cemeteries (Figure 2). Both sites dated be- tween 70-400AD (see Table 1), presented archaeo- logical material consistent with Roman-British populations, and are thought to have been small urban populations with access to marine resources from the River Severn (McWhirr et al., 1982). Early Pre-Medieval samples The Early Pre-Medieval samples came from a site in Thanet, Ozengell Grange (see Figure 2), dated to 500-600AD (see Table 1). The population is thought to have been small and coastal, with regular access to marine resources from the North Sea and/or the English Channel (Millard et at al., 1969). The Pre- Medieval period in Thanet is associated with new- ly developing urban areas following Roman occu- pation (McKinley et al., 2015). Figure 1. Cross sections displaying examples of worn and unworn teeth analysed. The left cross sec- tion, a Medieval upper first incisor, displays no occlusal wear. The right cross section, a Roman upper first incisor, displays occlusal wear and thus no data requiring the cuspal region was collected from it. 7 Dental Anthropology 2022 │ Volume 35│ Issue 01 Figure 2. Map of the United-Kingdom and Northern Ireland displaying the geographic location where the archaeological samples were excavated/modern-day samples were extracted. Shapes denote the samples geographic origin, colour the time period they associated with (multi coloured shapes thereby meaning individuals from more than one time period originated from the same location): Roman = Blue, Early Pre-Medieval = Red, Late Pre-Medieval = Orange, Medieval = Purple, Modern-day = Green. Similar guides to these populations’ context can be found in articles by Aris and colleagues (2020a, 2020b). Late Pre-Medieval samples The Late Pre-Medieval sample came from the Black Gate Cemetery site in Newcastle-Upon-Tyne (see Figure 2), dated to 800-1200AD (see Table 1). This was a large urban population with access to ma- rine resources through proximity to the River Tyne (Swales, 2012). Medieval samples The Medieval samples come from two sites: St Gregory’s Priory, Canterbury, and Fishergate House, York (see Figure 2). The sites were dated between 1100-1500AD (Hicks and Hicks, 2001) and 1000-1600AD (Holst, 2001) respectively (see Table 1). Both are documented to have been large urban populations (Hicks and Hicks, 2001; Holst, 2001). Modern-day samples The modern-day samples came from the UCL/ Kent collection, a repository of teeth collected from dental surgeries in northern England (Newcastle- Upon-Tyne) and southern Scotland (Glasgow) (see Figure 2). Ethical approval for histology research on this collection of teeth was obtained from the United Kingdom National Health Service research ethics committee (REC reference: 16/SC/0166; pro- ject ID: 203541). Sample Preparation Before any tooth was sectioned as a part of produc- ing the data set, resin casts were produced for each incisor, canine and molar using standard methods (Aris, 2020). Producing casts in this way allows for 8 Dental Anthropology 2022 │ Volume 35│ Issue 01 the reproduction of the surface morphology of dental crown, thus allowing for future researchers to analyse features not within the data such, such as crown morphology, microwear, and enamel sur- face features including perikymata and linear enamel hypoplasia. Thin sections were produced using standard histological procedures (e.g., Mahoney, 2008; Aris, 2020). All teeth were first embedded in an epoxy resin and hardener mixture (Buehler®) in order to minimise the possibility of teeth fracturing during the sectioning process. Embedded samples were then cut at low speeds using a diamond-edged wa- fering blade (Buehler® IsoMet 1000 Precision Cut- ter) through the apex of crown cusps at a longitu- dinal angle. Samples were then mounted on glass microscope slides and subsequently lapped using grinding pads (Buehler®) until around 120µm thick. Ground samples were then polished using 0.3µm aluminium oxide powder to remove any evidence of lapping. Polished samples were then placed within an ultrasonic bath for a two-minute period in order to remove any micro-debris before being dehydrated using 90% and 100% ethanol- based solutions (Fisher scientific®). Dehydrated sections were finally cleared using Histoclear® and mounted with a glass cover slip using a mounting medium (DPX®). All sections were examined using polarised light microscopy (Olympus BX53 Up- right Microscope). Analysis and image capture was conducted using micro imaging software (cellSens). Due to the requirements for cuts to be made precisely through the cusp and dentine horn apex in order for enamel growth and thickness data col- lected to be reliable (Aris et al., 2020b), lines were marked on the tooth to help guide the initial cut- ting of the teeth for each tooth type (Figure 3). Whether this method was successful was assessed by observing the shape of the dentine horn of each cross section – a sharp point (with a V-shaped ap- pearance; Smith et al., 2006a) at the apex denotes and precise cut; a curved/rounded apex a misa- ligned oblique cut (Reid and Guatelli-Steinberg, 2017). Where oblique cuts were noted the associat- ed sections were not used for data collection (Figure 4). Measurements Taken Daily secretion rates Daily secretion rates were reconstructed using standard methods for the inner, mid, and outer regions of the lateral and cuspal enamel areas of each tooth (e.g., Beynon et al., 1991a; Mahoney, 2008; Schwartz et al., 2001). Regions were deter- mined by dividing the length of the associated Figure 3. Diagram of how marks were made on upper first incisors, upper canines, and first molars (left to right respectively) before cutting to create a line through the cusp apex and dentine horn. The dashed red line displays the line created by the marks made at the blue crosses. Note the lack of blue cross on the unaligned root apex of the upper canine. The teeth displayed all came from the Fishergate House Medieval collection 9 Dental Anthropology 2022 │ Volume 35│ Issue 01 enamel area into three equal parts along the length of enamel prisms. Cuspal enamel regions were de- termined within the appositional enamel of each tooth, and DSRs were taken from the mesial cusps of molar teeth. Lateral enamel regions were deter- mined within the area of imbricational enamel equidistant between the dentine horn and the den- tal cervix. Lateral DSRs were taken from the buccal -mesial cusps of molar teeth, and from the labial enamel of canine and incisor teeth. For each region an initial measurement was made for the length of five adjacent cross striations following the long axis of an appropriate enamel prism. This measurement was then divided by five to give a mean daily rate of secretion (µm/day). This process was repeated five times to give a grand mean and standard deviation for each re- gion of each tooth. Cross striation measurements were all taken at between 20x and 40x magnifica- tion. Figure 5 illustrates how cuspal and lateral regions were split and how cross striations were counted along enamel prisms. Enamel thickness For each tooth, four 2D measures of enamel thick- ness were calculated: cuspal thickness (CT), lateral thickness (LT), relative enamel thickness (RET), and average enamel thickness (AET). Each was measured and calculated using a composite image produced by stitching together 20x magnified im- ages using cellSens digital software. RET is a dimensionless index and free-scale de- rivative of the average enamel thickness (AET) which encompasses the entire 2D surface area of an enamel cross section. AET (mm) is calculated by dividing the surface area by the length of the EDJ (enamel dentine junction) (Martin, 1983). RET is then calculated by dividing the associated AET by the square root of the dentine surface area of the surrounding EDJ and bi-cervical diameter (e.g., Smith et al., 2006a; Olenjniczak et al., 2008; Figure 6). Cuspal thickness was taken from the buccal- mesial cups of the molars and primary cusp of the incisors and canines. Lateral thickness was also Figure 4. Cross sections displaying aligned and misaligned cuts, both observed through the shape of the dentine horn (highlighted with dashed red lines). The left cross section, a Medieval upper first inci- sor, displays an aligned cut with sharp pointed, V-shaped, dentine horn apex. The right cross section, a Roman first molar, displays a misaligned cut with a rounded dentine horn. 10 Dental Anthropology 2022 │ Volume 35│ Issue 01 Figure 5. Diagrams of incisor (top left), canine (top right), and molar (bottom) cross sections with inner, mid, and outer regions for cuspal and lateral enamel regions isolated for DSR analysis. White squares show these enamel regions. The black square shows a 40x magnified superimposition of the mid lateral molar enamel. Black arrows indicate individual cross striations. 11 Dental Anthropology 2022 │ Volume 35│ Issue 01 taken from the mesial cusps of the molars, and from the labial region of incisor and canine enamel. Cuspal thickness (mm) was calculated by measur- ing the distance between the apex of the dentine horn and the cusp tip. Lateral thickness (mm) was calculated by measuring the maximum length be- tween the EDJ and the enamel surface along a line perpendicular to the EDJ. The location of this line determined within the area of the tooth between the dental cervix and the first Retzius line to form in contact with the outer enamel surface (see dot- ted lines of Figure 1). These two linear measure- ments have been presented in past studies under different abbreviations (Beynon and Wood, 1986; Grine, 2005; Hlusko et al., 2004; Mahoney, 2010; Schwartz, 2000a, 2000b). Pre-existing data Equivalent data to that which is provided in this article, regarding enamel secretion rates and thick- ness, has been routinely published in studies re- garding human enamel. A large number of those articles were compiled with details as to the enam- el variables analysed and context information of relevant human samples, in order to contextualise the novel data generated for this project. By com- piling this data it is easier to identify where the novel data presented here fills temporal and/or geographical gaps in existing data, and thus where gaps also persist. Where the same data has been utilised in multiple published works only one is detailed; preference was given to the original source where possible (Table 3). Note: Articles using similar data which have been published to date but are not included are those which utilised the data sets provided in this article (Aris et al., 2020a, 2020b; Aris and Street, 2021). Conclusions Data utility The combined data sets presented here represent the largest data repository of its kind in relation to developmental variables of human enamel in both archaeological and modern contexts. Moreover, it holds particular value in being the only such data set available which lists individual-level data for enamel growth and thickness for multiple tooth types and multiple different populations. This will allow for future research to have wider accessibil- ity to comparative data for both intra- and inter- species and population analyses of permanent enamel involving human samples. Moreover, it is Figure 6. Cross-sectional images and reconstructions of 2D enamel thickness measures taken for molars (left) and canines and incisors (right). C. the enamel cap area and B. the dentine encompassed by the enamel and bi-cervical diameter (double-headed arrow). The area of C. was divided by the length of the EDJ (marked by dotted red line) to give the average enamel thickness (AET) in mm. The AET is divided by the square root of the area of B and multiplied by 100 to give the relative enamel thickness (RET) (e.g. Martin, 1983), which is a dimensionless index. The dotted white lines (CT) illustrate the cuspal enamel thickness measurements (e.g. Beynon and Wood, 1986). The dashed white lines (LT) illustrate lateral enamel thickness measurements (e.g. Grine and Martin, 1988). Similar guides to taking these measures can also be found in an article by Aris and colleagues (2020b). 12 Dental Anthropology 2022 │ Volume 35│ Issue 01 Table 3. Existing published data for enamel DSRs and relevant thickness measures detailed with temporal and geographic contexts, tooth type information, and level at which data is available. Source Location Time Period Tooth Types N Data collected Data level presented at Cuspal DSRs Lateral DSRs DSR data Beynon et al., 1991b Unknown Unknown Molars 11-15 X X Species Lacruz and Bromage, 2006 Unknown Unknown Molars 10 X X Species Smith et al., 2007 Various Various First molars 21 X Species Smith et al., 2009 Germany Modern-day Third molars 7 X Species Mahoney, 2008 England and Scot- land Bronze-Age First molars 13 X Population Schwartz et al., 2001 England and South Africa Modern-day Canines 28 X X Sex Thickness data Source Location Time Period Tooth Types N RET CT LT Data level presented at Smith et al., 2006a and b* Various Middle Stone Age and Modern-day Molars 1-55 X Population Olejniczak et al., 2008* Various and un- known Various and unknown First molars 1-6 X Species Lockey, 2020 Unknown Unknown Molars 9-10 X Individual Martin, 1983 Unknown Unknown Molars 13 X Species Skinner et al., 2015 Various Unknown Molars 8-15 X Individual Smith et al., 2009 Germany Modern-day Third molars 8 X Species Smith et al., 2008 Various Various Various 12-58 X Species Sorenti et al., 2019 Madrid, Spain 20th Century Molars 20-31 X Sex Kono, 2004* Asia Various Molars 40-41 X X Population Grine, 1991 Unknown Unknown First molars 10 X X Species Grine, 2004 Various Modern-day Second mo- lars 1-23 X X Population Reid and Dean, 2006 Various Various Various 15-37 X Population Gantt and Rafter, 1998 Unknown Unknown Molars 3-23 X X Species Mahoney, 2010 England and Scot- land Various Molars 69 X X Population Suwa and Kono, 2005* Ohio, USA 800-1100AD First molars 31-37 X X Population Kono et al., 2002* Asia Unknown First molars 5 X X Individual Macho and Berner, 1993 Zwentendorf, Austria 1100AD First molars 21 X Population Saunders et al., 2007 Belleville, Canada 1821-1874AD Canines and premolars 72 X Sex Feeney et al., 2010* Indonesia Modern-day Canines 7-21 X Population Buti et al., 2017* Various Medieval and Clinical Canines 1-13 X Population *Some or all data generated within a 3D context 13 Dental Anthropology 2022 │ Volume 35│ Issue 01 hoped that the compilation of similar data availa- ble in past research publications here will assist in researchers locating suitable comparative data re- garding enamel growth and thickness data in addi- tion to that provided here. For specific examples of the data’s utility, all arti- cles which have utilised any data presented here compromise the work of Aris (2020), Aris and col- leagues (2020a, 2020b), and Aris and Street (2021). Throughout these articles, all content here includ- ing enamel DSRs, enamel thickness, and methodo- logical approaches, are used in specific research projects. Data ethics and acknowledgements Data of the kind presented here is collected via de- structive methods, which has a permanent impact on the collections analysed, and thereby their curating institutions. As a result, while this data is publicly available for use in future research, it is strongly recommended that such research acknowledge both the generosity and ethical strin- gency of the curators acknowledged in this article. Moreover, further care must be taken when utilis- ing the modern-day data from the UCL/Kent col- lection. Not only should the University of Kent be acknowledged, but it should be detailed that the ethical approval for histological research on this collection of teeth was obtained from the United Kingdom National Health Service research ethics committee. Furthermore, the REC reference: 16/ SC/0166; project ID: 203541, should also be noted (as it has been here in section 2.1.5). Acknowledgements Thanks go to the Corinium Museum, Trust for Thanet Archaeology, and the Universities of Durham, Kent, and Sheffield for granting permis- sion to sample the teeth sectioned as a part of de- veloping this repository. Thanks also go to the two anonymous reviewers and editor for their positive feedback and comments which helped greatly im- prove this article. REFERENCES Aris, C. (2020). The histological paradox: Method- ology and efficacy of dental sectioning. Papers from the Institute of Archaeology, 29(1), 1-16. Aris, C., Mahoney, P., & Deter, C. (2020a). 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