Laser Ablation of Modern Human Cementum The examination of trace element profiles by Lisa Lefever A Thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfilment of the requirements of the degree of MASTER OF ARTS Department of Anthropology University of Manitoba Winnipeg, Manitoba ©2010 ii Abstract This study used LA-ICP-MS on a documented sample of modern teeth to sample from a continuous line across the cementum increments thus creating a temporal line graph of the elemental composition against distance. The knowledge of cementum was extended through (1) a more complete elemental composition analysis and (2) the relation of element distribution to the ultrastructure structure throughout the life of a tooth. This study was exploratory and demonstrated that lead, zinc, mercury, and barium follow the same general line of changes, and most likely represent changes in health and exposure to these metals in the general environment. Copper, manganese and vanadium varied very little. Technological limitations prevented the examination of element levels in any one annulation. iii Acknowledgements I would like to thank my advisor, Rob Hoppa, who constantly encouraged me to finish, and managed to wade through my random writings and massive literature review. I greatly appreciate the chance to show I can eventually make my way through a thesis. Secondly, I could not have accomplished any of this without the help from the rest of my external committee member, Dr Norman Halden, who graciously showed me the ways of laser ablation and trace elements, and granted me access to his cool toys. Also, listening to a Scottish accent makes everything that much more interesting. Another big thanks goes out to my other committee member Dr Gregory Monks, who kept me on my cementum and grammatical toes. Other thanks definitely goes out to Panseok Yang, who sat with me, explained, and entertained me while we lasered my teeth. Sorry for making you analyze so many teeth. I’d also like to thank the rest of the Geological Sciences department, mainly Dr Mostafa Fayek and Rong Liu, who let me see what the SIMS could do analysis- and explosion-wise. A huge thanks goes to my friends and family back in Edmonton, who never stopped bugging me to finish this thing off. A special thanks to Megan Caldwell and Rebecca Kerby, who kept me ‘sane’ with coffee and Tim Hortons breaks, and advice on how to handle graduate life. I probably would have quit without your guys’ support. Laurie Shead also deserves a thank you for showing me the ways of BDIAL and the important software (and more than once). You also let me talk cementum with someone who actually understood what I was saying. Thanks to my dedicated Helper Monkey, Ben Collins, who sectioned and polished my numerous slides, a far cry from being allowed to play with lasers. iv I also greatly appreciate all who attempted to read over my chapters (Kristjan Weigl, Katie Waterhouse, Nic Cawthorne, and my mom, whose brain I nearly broke with my extended lit review. All of this research was made possible by the financial aid of the Canada Research Chairs Program, the Faculty of Geological Sciences, and the Anthropology Department of the University of Manitoba. I’d also like to thank Dr Curran from the Faculty of Dentistry, who collected all of the teeth. v Table of Contents Abstract………………………………………………………………………………….ii Acknowledgments……………………………………………………………………….iv List of Figures…………………………………………………………………………..vii List of Tables……………………………………………………………………………xii Chapter 1: Introduction………………………………………………………………..1 Chapter 2: Dental Development……………………………………………………….8 Introduction……………………………………………………………………...8 Odontogenesis/Cementogenesis…………………………………………………8 Cementum………………………………………………………………………12 Cementum Annulations………………………………………………………...14 Why the visual difference?.......................................................................14 Fibre orientation differences……………………………………………15 Density…………………………………………………………………..16 Age Estimation from Cementum Annulations………………………………….19 Summary………………………………………………………………………..22 Chapter 3: Tooth Chemistry………………………………………………………….23 Introduction……………………………………………………………………..23 Elements...……………………………………………………………………...24 Magnesium……………………………………………………………..24 vi Zinc……………………………………………………………………..24 Manganese……………………………………………………………...25 Copper………………………………………………………………….26 Lead…………………………………………………………………….27 Mercury………………………………………………………………...28 Vanadium………………………………………………………………29 Strontium……………………………………………………………….30 Barium………………………………………………………………….31 Absorption……………………………………………………………………..31 Diffusion……………………………………………………………………….32 Homeostasis……………………………………………………………………33 Cementum Studies……………………………………………………………..33 LA-ICP-MS……………………………………………………………………35 Standard Reference Material…………………………………………………..38 Linear vs Spot………………………………………………………………….38 Summary……………………………………………………………………….39 Chapter 4: Materials and Methods………………………………………………….40 Tooth Sample………………………………………………………………….40 Sample Preparation……………………………………………………………43 Cementum Imaging and Counting…………………………………………….44 Laser Ablation Protocol……………………………………………………….44 Electron Probe Micro-Analysis……………………………………………….46 Analysis……………………………………………………………………….46 vii Chapter 5: Results……………………………………………………………………48 Homogeneity of Ca from EPMA……………………………………………..48 Cementum Annulations……………………………………………………….48 Element Analysis……………………………………………………………..51 1……………………………………………………………………….51 4............................................................................................................55 13……………………………………………………………………..58 16……………………………………………………………………..58 19……………………………………………………………………..63 22……………………………………………………………………..69 24……………………………………………………………………..94 27……………………………………………………………………..104 28……………………………………………………………………..108 35……………………………………………………………………..112 37……………………………………………………………………..121 44……………………………………………………………………..124 48……………………………………………………………………..128 Summary……………………………………………………………………..131 Chapter 6: Discussion and Conclusions…………………………………………..133 Introduction………………………………………………………………….133 Lead………………………………………………………………………….133 Zinc…………………………………………………………………………..134 viii Magnesium…………………………………………………………………..135 Strontium…………………………………………………………………….137 Barium……………………………………………………………………….138 Mercury……………………………………………………………………...138 Copper, Manganese, Vanadium……………………………………………..140 Trends………………………………………………………………………..141 Lead and Zinc………………………………………………………..142 Outer Edge…………………………………………………………...143 Cellularity and Ultrastructure………………………………………..144 Diffusion……………………………………………………………..145 Limitations…………………………………………………………………...146 Future Directions……………………………………………………………..147 Conclusions…………………………………………………………………..148 References……………………………………………………………………………151 ix List of Figures Figure 1 Count of tooth type by sex ................................................................................... 42 Figure 2 Count of teeth by decade ..................................................................................... 42 Figure 3 EPMA by weight for tooth 22-3 .......................................................................... 49 Figure 4 SEM photo of ablation line .................................................................................. 49 Figure 5 Raw laser ablation levels of Ca for tooth 22-3 .................................................... 50 Figure 6 Tooth 22-3 ........................................................................................................... 50 Figure 7 Tooth 24-3 (green dots mark the increments) ..................................................... 52 Figure 8 Raw calcium profile of tooth 1-2. ........................................................................ 52 Figure 9 Raw Ca profile of tooth 1-4 ................................................................................. 53 Figure 10 Standardized mercury and lead profiles of tooth 1-2 ........................................ 54 Figure 11 Standardized mercury and lead profiles of tooth 1-4 ........................................ 56 Figure 12 Standardized mercury, lead and zinc profiles of tooth 4-3…………………... 56 Figure 13 Raw calcium profile of tooth 4-3 ....................................................................... 57 Figure 14 Standardized magnesium profile of tooth 4-3 ................................................... 57 Figure 15 Standardized mercury, lead and zinc profiles of tooth 4-4 ................................ 59 Figure 16 Standardized mercury, lead and zinc profiles of tooth 4-5 ................................ 59 Figure 17 Standardized manganese, barium and copper profiles of tooth 4-3. ................. 60 Figure 18 Standardized manganese, copper and barium profiles of tooth 4-4 (without outer peak) ......................................................................................................................... 60 Figure 19 Standardized manganese, copper and barium profiles of tooth 4-5 .................. 61 Figure 20 Standardized mercury, lead and zinc profiles of tooth 13-2 .............................. 61 Figure 21 Raw calcium profile of tooth 13-2 ..................................................................... 62 Figure 22 Standardized lead , zinc and barium profiles of tooth 16-2. .............................. 62 Figure 23 Standardized mercury profile of tooth 16-2. ..................................................... 64 Figure 24 Standardized magnesium profile of tooth 16-2. ................................................ 64 Figure 25 Standardized magnesium profile of tooth 16-5.