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158 changes: 100 additions & 58 deletions 01-intro.qmd
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::: {.content-visible when-format="html"}
{{< var intro.status >}} {{< var intro.version >}}

::: {.callout-note icon="false"}

## Summary {-}

What is dental calculus? Is it bad? What makes it so interesting to archaeologists?
What is dental calculus? Why does it grow on our teeth? Is it bad?
What makes it so interesting to archaeologists?
Am I going to answer any of these questions?

:::
:::

```{r}
Expand All @@ -30,7 +35,7 @@ may also know it as tartar or mineralised plaque. In other languages the word is
often related to "tooth stones". In fact, calculus is itself latin for 'pebble'.
This was orginially used as a term for mathematical calculations using counting
stones, and only later used to describe calicifications in the human body
(https://www.etymonline.com/word/calculus). This can be the cause of some confusion,
(<https://www.etymonline.com/word/calculus>). This can be the cause of some confusion,
as calculus is also a branch of mathematics. If you see the the term 'calculus' in
this disseration, you can safely assume that I'm referring to stuff that grows
on your teeth and for which you receive lectures from your dentist, and not the
Expand Down Expand Up @@ -172,7 +177,7 @@ in a population, not just oral health<!--any other studies?-->. They suggest tha
individuals with more calculus are more at risk than individuals with less or no
calculus.

![Word cloud of most common dental terms in articles. Figure is from @pilloudOutliningDefinition2019, Figure 1](figures/wordcloud.png) {#fig-dental-terms}
![Word cloud of most common dental terms in articles. Figure is from @pilloudOutliningDefinition2019, Figure 1](figures/wordcloud.png){#fig-dental-terms}

This wide range of applications, and the fact that it's pretty much ubiquitous in the
past (thanks to poor oral hygiene), makes it a really exciting area for the future of
Expand Down Expand Up @@ -451,18 +456,18 @@ Often we can draw from clinical studies as there are common goals, e.g. discover
the aetiology and/or presentation of a disease. However, the motivation driving the
studies in archaeology and dental research are inherently different; although,
there is certainly overlap in some areas ([@fig-plot-and-wordclouds]B and C).
While clinical
dentistry is interested in the effect that diet (among many other factors) has on
the growth and development of plaque, archaeologists are more interested in the
effect that the growth and development of plaque has on what we can say about diet.
There is more interest in preventing dental calculus from forming in the first
place, so most studies focus on anti-microbial treatments and inhibition of biofilm
formation and plaque buildup [@extercateAAA2010].
Archaeologists are more interested in
questions related to how diet influences the growth of biofilms, and how fragments
become embedded inside, and what we can say about diet.
Further, the interest in dental calculus as a field of clinical research has been declining
since the 2000s, which, as far as I'm aware, is when the last studies growing dental calclulus
in a lab were conducted. We can see this by the number of clinical articles with
the term dental calculus in the title ([@fig-plot-and-wordclouds]A).
And they certainly aren't interested in how food debris becomes trapped inside our
calculus.
There is more interest in preventing dental calculus from forming in the first
place, so most studies focus on prevention of short-term dental plaque accumulation.
Dental calculus has also become less of a problem with the use of modern dental hygiene
practices and regular visits to the dentist [@velskoMicrobialDifferences2019].

Expand All @@ -474,29 +479,74 @@ nuisance to be removed and, ideally, prevented from forming in the first place.
This lack of systematic research specifically devoted to dental calculus as a substance,
rather than a means to an end, leaves a lot of questions regarding the expected
behaviour of dental calculus and how information from the past becomes trapped inside.
To summarise the summary: we need to ask more basic questions about dental calculus.

## Aims
## Aims {#intro-aims}

This disseration is a contribution to a dental-calculus-centric body of knowledge,
and addresses a gap in the fundamental research on dental calculus to further our
understanding of how we can use dental calculus to reconstruct the diets of people
in the past.
The main focus is the development, validation, and application of
a calcifying oral biofilm model to inform interpretations on archaeological dental
calculus.

This disseration is a contribution to a dental-calculus-centric body of knowledge.
The main focus of my dissertation is the development, validation, and application of
an oral biofilm model to inform interpretations on archaeological dental calculus.
In short, can I grow calculus in the lab? Is what I'm growing actually a substance
that resembles calculus? And can the model be used to inform archaeological research;
specifically, how should we interpret the food debris extracted from dental calculus?
specifically, how should we interpret the food debris extracted from dental calculus?

<!-- specific aims of the dissertation research (bullet-form) -->
Can a biofilm model provide useful ... for archaeological research?
<!-- specific aims of the dissertation research (bullet-form)
Can an oral biofilm model provide useful insights on the mechanisms by which dietary components are
incorporated into dental calculus and the biases produced in this process?
Can an oral biofilm model address some of the limitations associated with using
dental calculus to reconstruct past diets?
Produce a better understanding of how dietary intake relates to the record
of diet from dental calculus.
of diet from archaeological dental calculus.
Assess the potential and limitations of dental calculus to explore dietary and
non-dietary uses of plants in past populations. -->

<!-- "You can't possibly be a scientist if you mind people thinking that you're a fool." (so long and thanks... p. 108).
This means sometimes asking the apparently obvious questions, like how does food become trapped in dental calculus.
And occasionally you'll find that no one really has a good answer to these questions. (PREFACE?) -->

Explore the potential uses of dental calculus in archaeological research.

## Thesis outline and structure

To address the aims of the dissertation, I grew dental calculus
on lab equipment instead of inside a mouth.
If you have made it to this point, you have probably read [Chapter 1](#chap-intro),
in which I provide some context to the study of dental calculus in archaeology
and identify some areas that could benefit from further investigation.

[Chapter 2](#chap-background) provides some background information on oral biofilms
and oral biofilm models in more detail than I can do in the research articles
included in Chapters 3 and 4. So if you're already well-versed in oral
microbiology, feel free to skip to Chapter 3. If not, I recommend picking
up a textbook written by actual experts in the field of oral microbiology.
If, for some reason, you can't access one of these, feel free to read
[Chapter 2](#chap-background). I suppose there are worse
options than something written by a PhD student in archaeology.

To address the aims of the dissertation outlined earlier in [this chapter](#intro-aims),
I developed a protocol to grow dental
calculus in a lab [... on lab equipment] instead of inside a mouth. The reason
for using lab-grown biofilms instead of humans is that the *in vitro* lab model offers more
control over all the factors that go into the growth of dental calculus, at least
in theory. The real world is messy, and sometimes you need to remove things from
the real world to break it down and really get into the nitty gritty of how it works.
<!-- the next part is also in the discussion... -->
I chose to use a 24-well plate with a plastic substratum suspended from a lid. The model
was inoculated with whole saliva, which can be more difficult to control, but more
closely replicate the complex dynamics between oral bacteria during biofilm
formation, such as metabolic dependencies [@roderStudyingBacterial2016; @mcbainBiofilmModels2009].
My choice of model was partially driven by
available facilities and financial limitations, and partially by the benefits of being
able to generate a large number of samples under similar, adjustable conditions.
It's arguably also more realistic for the facilities and finances of most archaeological
departments and grants.
Our model uses a simplified high-throughput setup more commonly seen in shorter-term
biofilm models that mainly focus on dental plaque [@extercateAAA2010; @tianUsingDGGE2010].
Using oral biofilm models to grow dental calculus is in
no way a novel concept. In fact, it has been applied for decades to study
the growth and mineralisation of biofilms
Expand All @@ -506,52 +556,44 @@ select species
determined by the researchers (defined consortium), and multiple species from some
natural source (the human mouth, for example). I will cover the different types of models
in more detail in [Chapter 2](#background).
I chose to use a 24-well plate with a plastic substratum suspended from a lid. The model
was inoculated with whole saliva. Multispecies biofilms inoculated with whole saliva
are more difficult to control, but are a
more realistic model since they can include the complex dynamics between the oral
bacteria during biofilm formation. My choice of model was partially driven by
available facilities and financial limitations, and partially by the benefits of being
able to generate a large number of samples under similar, adjustable conditions.
It's arguably also more realistic for the facilities and finances of most archaeological
departments and grants.
Since there are many biofilm models to choose from, developing a new protocol may
seem counter-productive; however, few are developed for long-term
growth and even fewer with the purpose of mineralising the biofilm to form dental calculus.
One of the exceptions involves a highly complex
setup that is unlikely to be supported by budgets and facilities available to most
archaeological laboratories [@sissonsMultistationPlaque1991].

After developing a working protocol, the next step was to determine if the stuff
I grew in the lab is actually
dental calculus. Or at least something close enough that we can use
it to explore our research questions.
To do this, we (myself and coauthors) determined the mineral
and bacterial composition of our model using Fourier Transform Infrared (FTIR)
spectroscopy and metagenomic classification [Chapter 3](#byoc-valid).
We then compared the results of these analyses to naturally grown dental calculus,
both modern and archaeological.

Being confident that our model looks and behaves like human dental calculus,
we then set out to test some very basic [properties] of starch
grains within dental calculus.
[Chapter 4](#byoc-starch) is a research article where we 'fed' the biofilm with
a known quantity of starch granules during the growth period to see if the input
quantity/ratio matched the extracted quantity (or output). Those who are
familiar with dental calculus research will not be surprised that it did not.
The more interesting outcome of the study is the more detailed explanation of how
the input and output starch quantities were mismatched.

<!--Move to a Preface chapter?-->
[Chapter 1](#chap-intro) is a brief introduction/rant on the topic of dental calculus and its
current applications in archaeology, which I assume you have just finished reading.
I do my best to contextualise the study of dental calculus
and identify some areas where we may have some additional questions.
[Chapter 2](#chap-background) provides some background information on oral biofilms
and oral biofilm models in more detail than I can do in the research articles
included in Chapters 3 and 4. So if you're already well-versed in oral
microbiology, feel free to skip to Chapter 3. If not, I recommend picking
up a textbook written by actual experts in the field of oral microbiology.
If, for some reason, you can't access one of these, feel free to read
[Chapter 2](#chap-background). I suppose there are worse
alternatives than something written by a PhD student in archaeology.
[Chapter 3](#byoc-valid) is about developing and validating the oral biofilm
model. In other words: is what we're
growing actually dental calculus, or ar least close enough that we can use
it to explore our research questions?
Specifically, it is a research article where we (myself and coauthors)
examine the applicability of
our biofilm model as a proxy for dental calculus.
We used Fourier Transform Infrared Spectroscopy (FTIR) to examine the mineral
composition of the model calculus and compared it to reference spectra
of real calculus.
[Chapter 4](#byoc-starch) is a research article where we used the biofilm model to
look at how well starch granules are incorporated into dental calculus.
We 'fed' the biofilm with a known quantity of starch granules
during the growth period to see if the input quantity/ratio matched the extracted
quantity (or output).
[Chapter 5](#mb11CalculusPilot) is a separate article, in the sense that it doesn't
involve the biofilm model in any way. Rather, it addresses the theme of the overall
utility of dental calculus in archaeological research.
We look at possible medicinal compounds in the dental
calculus of a Post-medieval Dutch population. We employed Ultra High Performance
Liquid Chromatography coupled with tandem Mass Spectrometry (UHPLC-MS/MS) to identify
various compounds in dental calculus, including alkaloids and other compounds.
It shows the potential of dental calculus to inform about past practices, but also
highlights some of the limitations we are currently experiencing in the field.
[Chapter 6](#chap-discussion) is a discussion on the limitations and future potential of
dental calulus in the field of archaeology, and what biofilms can contribute.
dental calulus in the field of archaeology, and what biofilm models can contribute to our
understanding of past diet.

## References {-}
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::: {.content-visible when-format="html"}
{{< var background.status >}} {{< var background.version >}}

::: {.callout-note icon="false"}

## Summary {-}

At any given moment, there are millions, if not billions, of microorganisms calling
Expand Down Expand Up @@ -36,6 +38,7 @@ be too complicated. Here, we can study the system under highly controlled condit
to different to try and understand why it acts the way it does in disease
and health.

:::
:::

The human mouth, or oral cavity, contains many different types of surfaces
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---
bibliography: articles/byoc-valid/07-publication/references.bib
---

# Assessing the validity of a calcifying oral biofilm model as a suitable proxy for dental calculus {#byoc-valid}

::: {.content-visible when-format="html"}
{{< var article1.status >}} {{< var article1.version >}}
{{< var article1.badges.status >}} {{< var article1.badges.version >}} {{< var article1.badges.doi >}}

::: {.callout-note icon="false"}

## Summary {-}

Article in progress. Validation of the BYOC (build your own calculus) model using FTIR for the mineral
composition and metagenomic analysis for the bacterial composition.
This chapter is an article that describes a protocol for the growth of a calcifying
oral biofilm model, or artificial dental calculus. We also make sure that the
artificial dental calculus is a good substitute for the real thing by determining
the bacterial and mineral makeup of our model calculus and compare it to natural
dental calculus, both archaeological and modern.

:::

:::

```{r}
#| label: setup-byoc-valid
library(here)
library(readr)
#knitr::opts_knit$set(root.dir = here())
#source("articles/byoc-valid/02-scripts/99_setup-qmd.R", local = T)
```


{{< include articles/byoc-valid/07-publication/01-intro.qmd >}}
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---

::: {.content-visible when-format="html"}
{{< var article2.status >}} {{< var article2.version >}} {{< var article2.doi >}}
{{< var article2.badges.status >}} {{< var article2.badges.version >}} {{< var article2.badges.doi >}}

::: {.callout-note icon="false"}

# Summary {-}

Expand All @@ -18,9 +20,10 @@ of consumed starch is retained by the calculus. The size of starch granules also
influences the likelihood of retention, with larger granules less likely to be
trapped in the calculus.

Preprint currently available on [bioRxiv](https://www.biorxiv.org/content/10.1101/2021.10.27.466104v1).
Published in [Frontiers in Earth Science](). Preprint available on [bioRxiv](https://www.biorxiv.org/content/10.1101/2021.10.27.466104v1).
Data and code available on [OSF](https://osf.io/uc5qy/).
:::
:::

```{r setup-starch, include=FALSE}
knitr::opts_chunk$set(
Expand All @@ -37,6 +40,7 @@ library(broom)
library(here)
library(patchwork)
library(ggplot2)
library(rticles)
devtools::load_all("articles/byoc-starch/")
plt1_ph1 <- readr::read_tsv(
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Expand Up @@ -5,14 +5,18 @@ title: Multiproxy analysis exploring patterns of diet and disease in dental calc
---

::: {.content-visible when-format="html"}
{{< var article3.status >}} {{< var article3.version >}} {{< var article3.doi >}}
{{< var article3.badges.status >}} {{< var article3.badges.version >}} {{< var article3.badges.doi >}}

::: {.callout-note icon="false"}

## Summary {-}

We used a fancy chemical method to find different types of food
and possible medicine
in dental calculus from, Middenbeemster, a rural 19th century
archaeological population in the Netherlands.

:::
:::

```{r}
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0 99-cv.Rmd → 99-cv.qmd
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9 changes: 0 additions & 9 deletions CHANGELOG

This file was deleted.

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Expand Up @@ -24,8 +24,8 @@ book:
right:
- icon: github
href: https://github.com/bbartholdy
- icon: twitter
href: https://twitter.com/osteobjorn
- icon: mastodon
href: https://fediscience.org/@bjorn
chapters:
- index.qmd
- 01-intro.qmd
Expand All @@ -34,6 +34,8 @@ book:
- 04-article.qmd
- 05-article.qmd
- 06-discussion.qmd
# appendices:
# - supp-mat.qmd

format:
html:
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