Impact of chemosignals released by

anxiety body odor on the performance of

dental students

Synnøve Lind and Cathinka M B Leegaard

Supervisor: Bano Singh

D.D.S., Ph.D.

Department of Oral Surgery and Oral Medicine

Faculty of Dentistry

University of Oslo

Master thesis Faculty of Dentistry, University of Oslo

Mai-2018

3

Contents

Acknowledgements .................................................................................................................... 4

Article published in Chemical Senses ......................................................................................... 5

Abbreviations ............................................................................................................................. 6

Norwegian abstract .................................................................................................................... 7

ABSTRACT ................................................................................................................................... 9

1 INTRODUCTION ..................................................................................................................... 11

2 AIM ........................................................................................................................................ 15

3 MATERIALS AND METHODS .................................................................................................. 16

3.1 Participants ..................................................................................................................... 16

3.1.1 Exclusion and inclusion criteria ............................................................................... 16

3.2 Experimental setup ........................................................................................................ 16

3.3 Data analysis, statistical analysis .................................................................................... 21

4 RESULTS ................................................................................................................................. 22

4.1 Participant demographic ................................................................................................ 22

4.2 Perceptual olfactory ratings ........................................................................................... 22

4.3 Score comparisons of the three different odor conditions ........................................... 23

5 DISCUSSION ........................................................................................................................... 26

6 CONCLUSION ......................................................................................................................... 28

Reference list ............................................................................................................................ 29

Appendix................................................................................................................................... 32

Acknowledgements

We would like to thank our supervisor Dr. Bano Singh at the Department of Oral Surgery and

Oral Medicine Faculty of Dentistry, University of Oslo, for the idea of research on this

interesting field and for all the guidance through the work of assignment. We would also like

to thank Dr. Valentina Parma, International school for Advanced Studies (SISSA), for guiding

us through the practical part of the study, with valuable help with the statistics and for all

the work with the article published in the international journal Chemical Senses. Our co-

author, Alix Young Vik, Professor at Institute of Clinical Dentistry, University of Oslo, also

contributed with proofreading the script of the article and we thank her for this.

Furthermore, we express our sincere appreciation to Inger Hattestad Henriksen, dental

instructor at the Dental Skill Lab at the Faculty of Dentistry of University of Oslo, for clinial

guidance in scoring the dental work performed by the test students. Last but not least, we

express our gratitude to the 3rd and 4th year dental students who participated in this study.

5

Article published in Chemical Senses

Abbreviations

BO – body odors

mABO – masked anxiety body odor

mRBO – masked rest body odor

mCTRL – masked control

STICSA – State-Trait Inventory for Cognitive and Somatic Anxiety

VAS – visual analogous scale

LMM – Linear mixed models

7

Norwegian abstract

Tannlegestudenters kliniske ferdigheter påvirkes av angstmolekyler

kommunisert via kroppslukter

Introduksjon: Ubevisst kommunikasjon via humane kroppslukter er kjent for å kunne

overføre angstrelaterte signaler og føre til endringer i atferd. Til tross for påvirkningen av slik

kommunikasjon i situasjoner som for eksempel tannbehandling, er det forsket lite på feltet.

Hensikt: Det vi ønsket med denne studien var å undersøke om angst uttrykt som

luktmolekyler alene, uten visuelle og auditive tegn, kan påvirke hvordan en tannlegestudent

utfører sine kliniske oppgaver.

Materialer og metoder: Studien besto av tre faser: innsamling av kroppslukt fra donorer,

utføring av bestemte oppgaver av deltakere og vurdering av de utførte oppgavene.

Fase 1: Innsamling av kroppslukter i to ulike situasjoner, angst og hvile, fra 24 friske

tannlegestudenter på fjerdeåret, kvinner og menn i 20-årene. Innsamlingen foregikk ved at

hver student bar t-skjorte under en tretimers klinikkøkt (angstsituasjon) og under en

tretimers forelesning (hvilesituasjon) på ulike dager. For å unngå kontaminering av lukt, ble

deltakerne bedt om ikke å innta enkelte matvarer og alkohol et døgn før innsamlingen, samt

unngå røyk og bruk av deodorant på innsamlingsdagen. I etterkant av innsamlingene

evaluerte deltakerne sin egen opplevelse av stress ved hjelp av et skjema. T-skjortene ble

umiddelbart pakket ned i lufttette poser og lagret i fryser ved -18 grader.

Fase 2: Utføring av bestemte tannlegeoppgaver av studenter under ulike luktforhold. T-

skjortene med kroppslukt (angst og hvile) ble maskert med 50 μl eugenol i hver armhule. I

tillegg ble nøytrale t-skjorter uten kroppslukt (kontroll) også maskert med samme mengde

eugenol. Tredjeårsstudenter, 24 menn og kvinner, utførte de samme kavitetsprepareringene

på plasttenner under de tre ulike luktforholdene (angst, hvile og nøytral) ved separate økter.

I forkant av forsøket gjennomgikk studentene en lukttest og besvarte spørreskjemaer for å

vurdere kognitiv og somatisk angst. Etter hver økt vurderte studentene t-skjortens lukt,

oppgavens vanskelighetsgrad og eget stressnivå. Studentene var ikke klar over hvilket

luktforhold som ble brukt når. Forsøkene foregikk på Ferdighetssenteret ved Universitetet i

Oslo, hvor studenter ved Det odontologiske fakultetet utfører preklinisk arbeid og tilegner

seg praktiske ferdigheter.

Fase 3: Vurdering av oppgavene. Det ble laget en egen skala for å vurdere prestasjonene for

hver enkelt student for hvert enkelt forsøk (Singh and Henriksen Scale). Skalaen gikk fra 0-50

poeng hvor 50 var den beste poengsummen. Hver preparerte tann ble vurdert blindt ut ifra

denne skalaen og studenten fikk en totalscore for hvert av de tre luktforhold. Deretter ble

disse resultatene og all informasjon hentet fra studentene plottet inn i SPSS.

Resultater: Studentene oppnådde signifikant lavere score under påvirkning av mABO

sammenlignet med mCTRL og nær signifikant sammenlignet med mRBO. Det var ikke mulig å

skille de tre luktforholdene fra hverandre ved persepsjon. Den statistiske analysen viste at

det ikke var en signifikant forskjell i oppnådd poengscore mellom mRBO og mCTRL.

Konklusjon:

Til tross for at det ikke var mulig å skille luktforholdene fra hverandre, oppnådde studentene

en dårligere score ved utførelse av oppgavene under påvirkning av mABO sammenlignet

med mRBO og nær signifikant sammenlignet med mCTRL. Disse funnene indikerer at

angstmolekylene kan ha blitt overført fra pasient til student under utførelsen av oppgavene.

Disse resultatene taler for videre studier av hvordan angstinduserende molekyler fra pasient

kan påvirke tannlegen. Vår studie er den første studien som utforsker effekten av

menneskelig angstkommunikasjon gjennom kroppslukter i en tannbehandlingssituasjon.

Studien åpner opp for muligheten for å bruke kroppslukter under utdanning av tannleger, i

den prekliniske fasen.

9

ABSTRACT

Introduction: Human body odors (BO) are known to transfer anxiety-related signals, with

consequences for behavioral conspecifics in lack of conscious awareness. Despite the

widespread effects revealed, the impact of anxiety chemosignals on real-life situations has

not been fully explored.

Aim: The aim of this study was to investigate the effects of anxiety chemosignals on the

performance of dental students operating on phantom dental simulation units, where

phantoms were put on t-shirts imbued with human sweat.

Materials and methods:

Donors: 24 (17F, 22-28 yr, 23.7 ± 2.0 yr), 4th year dental students. Students wore t-shirts and

body odor was collected during two conditions:

• 3 hr clinical session (Anxiety body odor, ABO)

• 3 hr classroom session (Rest body odor, RBO)

Recipients: 24 (17F, 20-41 yr, 24.8 ± 5.6 yr) normosmic 3rd year dental students. Recipients

performed the same dental procedure thrice while smelling three odor conditions,

presented via a t-shirt on the dummy:

• ABO masked with 50 μl eugenol (mABO)

• RBO masked with 50 μl eugenol (mRBO)

• Clean t-shirt masked with 50 μl eugenol (mCTRL)

Dental task: Cavity preperations: 34 mo, 35 mo and 46 mod

Odor ratings: Intensity, familiarity, pleasantness, anxiety, disgust

Results:

Perceptual ratings: Linear mixed models with the subject as a random factor indicated that

the recipients did not perceptually distinguish the odor conditions, with regard to intensity,

pleasantness, anxiety, familiarity and disgust.

Dental performance: Linear mixed models with the subject as a random factor revealed that

participants received a significantly lower score while stimulated by mABO as compared to

mCTRL and close to significant compared to mRBO. No significant difference in score was

retrieved when participants smelled mRBO and mCTRL.

Bayesian statistics were applied to evaluate the likelihood of finding evidence of a true

difference between odor conditions. There was strong to very strong evidence of a

difference between the mABO/ mRBO and mABO/mCTRL scores. However, an anecdotal

difference was revealed between mRBO and mCTRL performance, suggesting inconclusive

evidence for a difference between these conditions.

Conclusion: Despite odor conditions being perceptually indistinguishable, exposure to mABO

resulted in a poorer performance by recipients’ compared to their performance under the

exposure to mRBO and mCTRL. These findings indicate that the performance of dental

students may be affected by the patients’ chemosensory transmitted anxiety. These findings

call for a careful evaluation of the anxiety-inducing effects of BO on dental professionals,

suggest the possibility of using chemosignals during dental training and represent the first

ecological evaluation of the effects of human anxiety chemosignal communication.

11

1 INTRODUCTION

Dental anxiety is a relatively consistent and well-documented phenomenon throughout the

world (Carter et al, 2014). The prevalence varies depending on the population and the

measurement techniques. A range of population studies on dental anxiety show an average

prevalence of 20% (Boman et al., 2013). Other studies reveal that 80% have some dental

anxiety, 2,5-20% experience high dental anxiety while 5-14% feel intense dental anxiety

(Saatchi et al., 2015). It has been estimated that about 2-3% suffer from dental phobia – the

most severe form of anxiety, while 60-80% are anxious about dental treatment (Stenvik,

2005). It is important to distinguish between different types of fear reactions; Fear is a

natural reaction to a stimulus that is perceived as threatening. Anxiety is a fear reaction that

is more general, future-oriented and not linked to a specific cue (Stein et al, 2010). Phobia is

an extreme and irrational fear towards objects or situations and must be diagnosed by a

doctor or a psychologist.

Severe dental anxiety has a negative impact on dental health (Hakeberg & Berggren, 1993,

Schuller et al., 2003) as it is related to reduced access to health services, increased risk of

oral health diseases, and consequent worsening of untreated oral symptoms, all of which

can reinforce the fear of dental procedures (Berggren & Meynert, 1984). Among patients

with severe dental anxiety it has been reported an increase in mental strain (Aartman,

1997), increase in sickness absence (Hakeberg & Berggren, 1993) and reduced quality of life

(Crofts-Barnes, 2010). In addition, patients with dental anxiety show complaints on a wide

range of other psychological dimensions (Aartman, 1997). Different types of interventions

have been explored to reduce the negative effects of dental anxiety in patients. This includes

cognitive behavior therapy (CBT), pharmacological therapy and sedation (Carter et al., 2014).

Although, literature regarding dental anxiety is in abundance, only a few studies have

assessed the effect of dental anxiety on dental professionals. According to one study, 80% of

the dental professionals find treating patients with dental anxiety problematic, mostly young

dentists (Brahm et al., 2013). Dental professionals report following reasons to explain why

they find these patients problematic to treat: The dentists feel helpless and possess a low

knowledge of fear reactions, also, the dentists find the working conditions being difficult in

both psychological and odontological aspect (Berggren 2001).

Recent research has explored the different elements of fear reactions from the patient’s

perspective: the physiological response, and the cognitive, emotional and behavioral

changes. Human chemosignal communication of anxiety offers the possibility to evaluate

whether the undetected anxiety of a patient may unconsciously affect the performance of

dental professionals. Humans are able to chemically convey transient information, such as

emotional states (Semin & de Groot, 2013). Several studies find evidence showing that

people are able to unconsciously process chemosensory messages of threat via body odors

(Lundström et al., 2008, Pause, 2012, Parma et al., 2017). It has previously been established

that, in threatening situations, animals use alarm pheromones to communicate danger. This

has probably been important for survival during the evolution, as there is emerging evidence

of analogous chemosensory stress cues in humans (Radulescu & Mujica-parodi, 2013).

How does the nose function? Peripheral smell organs called olfactory cells are located in the

superior part of the nasal cavity in the olfactory epithelium. The cells are primary neuronal

cells and are directly connected to the central nervous system, specifically to the limbic

system.

http://virginiaspairteas.blogspot.no/2016/02/smell-and-memory-how-olfactory-system.html

13

The limbic system consists of several brain structures located beneath the cerebrum, among

others the olfactory bulb, hippocampus, hypothalamus and amygdale. This part of the brain

is accountable for long-term memory, learning, emotions, behavior, motivation and

olfaction.

Pleasant fragrances lead to happiness and good emotions while unpleasant fragrances can

lead to stress, anxiety, fear and other such negative emotions. These emotions are

transferable to other recipients through body odor communication and can lead to changes

in the recipient. This is the explanation behind why some odors can arise such strong

emotions. What emotions that emerge depends on previous experiences and the general

state of the body.

http://essentialoilsforguide.com/body-systems/limbic-system/

To evaluate the role of chemosignals in dental performance, we used the facilities at the

Dental Skill Lab at the Faculty of Dentistry, University of Oslo. This is the first study, to our

knowledge, to have performed innovative research at the Dental Skill Lab in the field of Oral

Medicine and Cariology. Moreover, this is the first study to elucidate the effects of anxiety

BO on dental professional’s performance. The results from this master-thesis have resulted

in a publication in an internationally acclaimed journal of chemosensory research, Chemical

Senses (Singh et al., 2018), with an Impact factor 2,9. Also, it has led to two presentations on

international conferences and oral presentation at a national dental meeting at Geilo

(Appendix 1 and 2). Findings from this study have a great degree of impact in the field of

dentistry, as in this study we are elucidating an aspect of dental anxiety that has earlier been

unidentified.

15

2 AIM

The aim of this study was to investigate dental anxiety from an innovative perspective;

namely, evaluating whether or not, and to what degree the undetected anxiety of a patient

may affect the performance of dental students.

We defined the following hypothesis: The null hypothesis (Ho) was that there would be no

difference in performance scores based on the odor condition exposure. The alternative

hypothesis (H1) was that difference in the performance scores would be observed based on

the odor condition exposure.

3 MATERIALS AND METHODS

3.1 Participants

Dental students were recruited in the two following groups: one of donors and one of

recipients. The number of participants was 24 for each group, both female and male. The

group of donors consisted of 24 (17F, age range 22-28 yr, and mean age 23.7+- 2.0yr) 4th

year dental students and the group of recipients comprised 24 (17F, age range 20-41 yr, and

mean age 24.8 +- 5.6 yr) 3rd year dental students.

3.1.1 Exclusion and inclusion criteria

Donors

The inclusion criterion was being a 4th year dental student at the University of Oslo.

Recipients

The inclusion criterion was being a 3rd year dental student at the University of Oslo.

Exclusion criteria were head trauma, previous surgery in the head and neck region, everyday

drug use, chronic diseases and impaired sense of smell for the recipients. The donors and

the recipients should not be in contact with each other on a daily basis due to adaptation.

They should also be about the same age and same gender.

3.2 Experimental setup

This experimental study consisted of three phases: collection of body odors from donors,

performance of dental tasks by recipients and evaluation of the dental performances.

According to the regional ethical comity in Norway (REK), ethical approval was not required.

(REK 2106/1228). The study took place at the Faculty of Dentistry at the University of Oslo.

Informed written consent was obtained from both donors and recipients prior to the

experiments (Appendix 3).

17

Phase 1 – body odor collection

Prior to body odor collection, donor’s anxiety trait was evaluated using State-Trait Inventory

for Cognitive and Somatic Anxiety (STICSA), a questionnaire designed to measure subjective

cognitive and somatic anxiety. The questionnaire consists of 21 statements that can be used

to describe how people feel in general. Evaluating each statement from 1- 4, where 1 is not

at all and 4 is very much so, gives a total score between 21 and 84, where a high score

indicates a higher level of cognitive and somatic anxiety.

In order to avoid odor contamination, donors were asked to follow specific restrictions one

day prior to the body odor collection. They were asked not to ingest certain types of food

(asparagus, garlic and strong spices) and to refrain from alcohol, cigarette and snuff. Also,

they were asked to wash themselves with neutral shower gel and avoid deodorant and

perfume.

The donors were given clean, white and tight t-shirts to wear under respectively their clinical

outfit and their private clothing. Body odors were collected from donors during two different

sessions. Anxiety body odor (ABO) was collected during a three-hour clinical session at the

faculty of dentistry, which is considered rather stressful for the students. Rest body odor

(RBO) was collected during a three-hour classroom session where the students are relaxed.

Immediately after three hours of body odor collection, the t-shirts were packed in airtight

bags and stored in a freezer (-18OC). Clean, white t-shirts with no body odor (CTRL) were also

stored under the same conditions.

After body odor collection the donors were asked to rate their own experience of stress

during the collection session by answering a questionnaire with a visual analogous scale

(VAS). VAS is used for personal evaluation of a characteristic or an attitude that ranges from

one value to another. The scale went from 1 to 10, where 1 was not stressed at all and 10

represented the highest level of stress possible. For the collection of ABO, they also specified

which type of treatment they performed.

Phase 2 – Dental performance under different odor conditions

This phase of the study took place at the Dental Skill Lab at the Faculty of Dentistry of

University of Oslo. At this location dental students perform preclinical work and acquire

practical skills while training on simulation units with plastic teeth.

Ahead of the performance demographic and health information were collected from all

recipients. This included questions about medication, previous head trauma and nose or

smelling troubles, and was part of the inclusion/exclusion process. Also, they answered the

STICSA questionnaire to evaluate cognitive and somatic anxiety.

The olfactory function of all recipients was evaluated using Sniffin’ Sticks (Burghart,

Messtechnik, Wedel, Germany), a test of nasal chemosensory performance based on pen-

like odor dispensing devices. Odor identification ability was determined presenting the

recipients with twelve distinct odors, one by one. The recipients were given four options for

each odor having to identify the correct one. One of the prerequisites for participation in this

study was a score of minimum 10 out of maximum 12.

Immediately prior to the task performance all t-shirts were masked with 50µl eugenol in

each armpit. Eugenol was chosen because it is rated as neither pleasant nor unpleasant

(Alaoui-Ismaili et al, 1997) and that it is commonly found in dental environment. Recipients

performed the same dental procedure three times while smelling different odor conditions,

presented via a t-shirt on the phantom. However, the recipients were never aware of which

of the odor conditions they were working under. Recipients smelled the BO of same-sex

donors.

The three different odor conditions, all masked with eugenol, were Anxiety Body Odor

(mABO), Rest Body Odor (mRBO) and t-shirts without body odor (mCTRL). The dental task

was cavity preparation of tooth 34 MO (mesio-occlusal), tooth 35 MO and tooth 46 MOD

(mesio-occlusal-distal) performed on plastic teeth within one hour. Recipients were asked to

make the preparations keeping the principles of minimal invasive dentistry in mind. Ahead of

the task performance, recipients were asked to carefully evaluate the odor of the t-shirt on

19

the phantom. Using a VAS-questionnaire, recipients made odor ratings that included

intensity, pleasantness, anxiety, familiarity and disgust.

Immediately after each performance, plastic teeth with cavity preparations and their

neighbor teeth were collected and stored in separate paper bags. After each of the three

performances, the recipients evaluated task difficulty and personal stress level during the

task performance using another VAS-questionnaire.

Image 1: Dental student operating under unknown odor condition. The phantom is dressed

in a white t-shirt representing one of the three different odor conditions.

Phase 3 – Blinded evaluation of the dental performances

A special scale was made in order to evaluate and compare each of the three performances

for each recipient (Singh and Henriksen Scale). The following aspects were considered:

damage to neighbor teeth, pulpal depth, gingival height, occlusal depth, occlusal width and

buccal and lingual extension (Appendix 4). The scale extends from 0-50, where 50 is the

optimal score. Any defects were evaluated. In all the aspects listed above it was possible to

obtain a maximum of 2 points per tooth. The more severe defect, the lower score. In

addition, if a wrong tooth was handed in or the neighbor teeth were missing this decreased

the total score. Each prepared tooth was blindly evaluated in accordance with this scale,

giving the recipients a total score for each of the three odor conditions. The evaluation of

each task was done separately by three judges who then agreed on a final score. The judges

were blind to the participants ID and the odor condition.

Image 2: Phantom jaws with plastic teeth and paper bags for collection

of teeth from each of the three odor conditions.

21

3.3 Data analysis, statistical analysis

Data was analyzed using SPSS 24.0 (IBM, Armonk, NY, USA). Independent and paired t-tests

were used to compare normally distributed continuous variables. There was no data with

non-parametric values. All differences were considered significant at p<0.05. Bayesian

statistics were employed to evaluate the likelihood of a true difference in the results

calculated. Results were given in tables and boxplots.

4 RESULTS

4.1 Participant demographic

Mean STICSA-score for donors was 34.5 ± 9.7, while for the recipients it was 35.5 ± 6.7 out of

a maximum score of 84 and minimum score of 21. Evaluation of olfactory function using

Sniffin’ sticks among the recipients gave a mean score of 10,9 ± 1,1. There was no significant

difference in performance score comparing neither ethnicity nor gender.

4.2 Perceptual olfactory ratings

The recipients were not able to differentiate between the three odor conditions in terms of

intensity, pleasantness, familiarity, anxiety and disgust in a significant manner (table 1).

Condition 1

mABO

(mean ± SD)

Condition 2

mRBO

(mean ± SD)

Condition 3

mCTRL

(mean ± SD)

Intensity 26,2 ± 21,0 25 ± 17,5 22 ± 20,9

Pleasantness -0,042 ± 1,5 0,29 ± 2,1 0,98 ± 2,0

Familiarity 5,2 ± 2,6 5,2 ± 2,3 5,4 ± 2,9

Anxiety 3,2 ± 2,3 3,2 ± 2,5 2,9 ± 2,2

Disgust 1,7 ± 2,2 2,2 ± 2,7 2,0 ± 2,3

Table 1. Results of the odor perceptual ratings from different odor conditions obtained from recipients. No significant differences in perceptual ratings were observed for the three conditions.

23

4.3 Score comparisons of the three different odor conditions

Performance score was significantly lower under the influence of mABO compared to mRBO

and close to significant when compared to mCTRL. No significant difference in score was

seen when recipients were working under mRBO and mCTRL. (Figure 1)

Figure 1: Boxplot illustration showing the mean score from different conditions. Mean score retrieved during exposure to condition 1 (mABO) was significantly (p= 0.02) lower from mean score retrieved from condition 3 (controls), and close to significantly (p=0.08) lower from mean score retrieved from condition 2 (mRBO).

Bayesian statistics were used to consider the probability of the above-mentioned results

representing a true difference. Bayes factor is an alternative to classical hypothesis testing.

Our results show that overall; there is very strong evidence (BF=54) that the three odor

conditions are different. The strongest difference was found between mABO and

mCTRL(79.16 < BF10 < 92.04). There was also a strong difference between mABO og mRBO

(9.65 < BF10 < 12.91). On the contrary, the difference between mRBO and mCTRL (1.98 < BF01

< 3.47) was anectodat to moderate. Detailes in Fig. 2.

p = 0.02

p = 0.08

Figure 2: Cauchy prior distributions based on which evidence for true differences among the conditions are established. BF10 = evidence for the alternative hypothesis over the null; BF01 = evidence for the null hypothesis over the alternative.

25

Score comparisons of the three different odor conditions and interaction with perceived

task difficulty (Table 2)

Dependent

variable Contrast Estimate

Standard

error df t ratio p value

Score

mABO-

mRBO -4.77 1.55 43 -3.08 0.010

mABO-

mCTRL -6.06 1.51 43 -4.27 0.0003

mRBO-

mCTRL -1.68 1.53 43 -1.10 0.52

Table 2: Results of the LMMs on the score obtained as evaluation of the dental performance in interaction with the perceived task difficulty with the test subject as a random factor. The p-values reported are adjusted with the Tukey method for comparing a family of three estimates. Evaluation of the different aspects of the task performed showed that receipts performed

poorly when exposed to anxiety body odor. Recipients scored lower on pulpal depth, gingival

height, occlusal depth and occlusal breadth during mABO exposure compared to both mRBO

and mCTRL (Table 3)

Table 3: Performance score of the different aspects evaluated

5 DISCUSSION

The major finding of this study is that performance score dropped significantly during

exposure to mABO compared to mCTRL and close to significant compared to mRBO.

Therefore, the null hypothesis is rejected. This indicates that the recipients were affected by

anxiety chemosignals communicated via body odor. On the contrary, the two other

conditions, rest body odor and neutral control, resulted in no significant differences in the

performance scores. This can be explained by the absence of chemosignals transmitting any

type of anxiety or stress during these sessions.

The recipients were never aware of which odor condition they performed under during the

different sessions. Also, the judges were blind to the odor conditions when evaluating the

performance scores. The fact that the recipients were not consciously able to distinguish the

three different odor conditions, suggests that this type of body odor may be processed

without conscious awareness. This may have been of great importance during evolution and

survival (Hoskison, 2013).

One may argue that the differences in performance scores are the result of a general state of

anxiety and stress, or other factors like natural performance variations. However, such

coincidences would not result in a significant difference in the performance scores.

Another possible confounding factor may be the order of the tasks and possible

improvement after repeatedly performing the same tasks. The order of the tasks varied

among the recipients, although the majority performed mABO first. This may be a

disadvantage because the recipients were not familiar with the procedure, which can lead to

poorer results.

Our results show that even when masking the body odors with eugenol, the recipients were

affected by the anxiety chemosignals. In everyday life, this can correspond to sweat signals

masked by deodorants or other fragrances like perfume or smells of chemical compounds

used in a dental clinic. Since the recipients represent inexperienced dental students and not

professional dentists, the level of expertise may have been relevant to the performance

scores obtained. If the recipients were professional dentists, the result may have been

27

different because they may not be affected by anxiety chemosignals in the same degree. It is

possible that the dental students may be more sensitive to the negative effects of the

mABO. In a clinical situation a patient would normally show visual signs of anxiety, express

feelings verbally etc. and not only transmitting anxiety chemosignals. Our study shows that

anxiety chemosignals alone may affect a dental procedure. Therefore, this can open up to

the possibility of using human chemosignals during dental training to prepare the students

for real patients.

Our findings represent the first empirical account showing that the BO of anxiety, even when

masked by other fragrances, as it often happens in real-life situations when sweat signals are

masked by deodorants or other fragranced products, impair the performance of naïve

smellers in a way that carries significant consequences in the field of dentistry.

Moreover, this is the first time the Dental Skill Lab has been used for research purposes.

Such research may contribute in making the phantom-simulation units more human and is

beneficial in achieving an early awareness of treating anxious patients if used in dental

student training in the future.

6 CONCLUSION

Recipients performed significantly poorer under the exposure to anxiety body odor, despite

not being able to perceptually differentiate between the three odor conditions. These

findings indicate that the performance of dental students may be unknowingly affected by

anxiety chemosignals communicated via transmission of body odors. This may be of

importance in the dental treatment of anxious patients and (could be relevant focusing on)

during dental training. These findings call for a careful evaluation of the anxiety-inducing

effects of BO on dental professionals. The results from this study suggest the possibility of

using chemosignals during dental training so that the dental students get familiar with the

patients state of anxiety already in the early stage of pre-clinical training. To summarize,

these findings represent the first ecological evaluation of the effects of human anxiety

chemosignal communication in dentistry.

29

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Appendix

1. Poster 1 (Achems)

2. Abstract 2 (ORCA)

3. Information to participants (information sheet for participation)

4. Singh & Henriksen Scale

33

Abstract for ORCA 2017

The effect of anxiety body odour on dental students’ performance P. B. Singh* a) c), S. Lind a), M.C.B. Leegaard a), A. Young a), V. Parma b)

p.b.singh@odont.uio.no

a) Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Norway

b) International School for Advanced Studies (SISSA), Trieste, Italy

c) Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, Oslo, Norway

Dental anxiety is a common phenomenon in both young and adult patients. Human body odours (BO)

can transfer anxiety-related signals, with consequences for conspecifics emerging at the behavioural

level. The aim of this study was to evaluate the effect of human body odour chemosignals on the

performance of dental students. Twenty-four 4th year dental students donated their body odour during

a clinical session (Anxiety BO) and a classroom session (Rest BO). Twenty-four age and gender-

matched 3rd year dental students (17 females, age: 24.83 y (± 5.58)] performed three dental procedures

while exposed to three odor conditions (anxiety BO, rest BO and a control condition consisting of a

clean t-shirt), masked with 50µl of eugenol. During three sessions at the preclinical laboratory

restorative dental procedures were performed on KaVo dental training models mounted on phantom

heads: tooth 34 MO minibox, tooth 35 MO box, tooth 46 MOD box. The restorative procedure was

scored on a range from 0 (poor) to excellent (50) based on: damage to neighbouring teeth, pulpal

depth, gingival height, occlusal depth and bredth, preparation on wrong teeth. Results from linear

mixed models indicated that the different odour conditions could not be perceptually distinguished by

the participants (ps>0.08). However, results reveal that the dental students’ performances were

significantly worse when exposed to the anxiety BO compared to rest BO and control (Score (range 0-

50): Masked Anxiety BO: 28 < RestBO: 33 < Masker: 35). The results were supported by Bayesian

statistics, indicating that there was a strong (BF=19) to very strong (BF=92) difference between the

dental performances under the different odour conditions. These findings suggest the need for

increased awareness of the anxiety-inducing effects of BO on dental professionals.

25-word summary: Students’ skills were affected by chemosignals as shown by poorer

performance when exposed to human anxiety body odour compared to rest or no body odour.

35

Det odontologiske fakultet ved Universitetet i Oslo

Forespørsel om deltakelse i forskningsprosjektet

KAN KROPPSLUKTER FRA PASIENTER MED

TANNLEGEANGST PÅVIRKE TANNLEGENS

KLINISKE FERDIGHETER?

Dette er et spørsmål til deg om å delta i et forskningsprosjekt for å se hvordan ulike

kroppslukter påvirker en tannleges arbeid. Forskningsprosjektet skal foregå Det odontologiske

fakultet i Oslo, både i Geitmyrsveien og på Ferdighetssenteret (FHS) på Gaustad. Det er

derfor valgt ut studenter som har kjennskap og tilknytning til FHS, og som kan dra nytte av

ekstra praktisk trening i forbindelse med forsøkene. Prosjektet er et samarbeid mellom Det

odontologiske fakultet i Oslo og SISSA – International School for Advanced Studies, Italia.

Hva innebærer PROSJEKTET?

Vi søker deltagere til to ulike deler av forsøket. Fjerdeårsstudenter inviteres til å donere

kroppslukt, mens tredjeårsstudenter inviteres til å utføre gitte oppgaver ved FHS.

Som donor skal du bære en t-skjorte under en tretimers klinikkøkt (stresset situasjon) og

under en tretimers forelesning (avslappet situasjon). Viktig forberedelse til disse

innsamlingene er at du unngår sterkt krydret mat, hvitløk, asparges, alkohol, tobakk og

parfymerte hygieneartikler et døgn i forkant.

Studentene som skal utføre arbeidsoppgavene ved FHS skal utføre de samme oppgavene tre

ganger under ulike luktforhold.

I prosjektet vil vi innhente og registrere opplysninger om deg. Du vil bli anonymisert, og de

eneste registrerte opplysninger blir alder, kjønn og svar på ulike spørreskjema.

Mulige fordeler og ulemper

En fordel for deg er at du får ekstra ferdighetstrening før eksamen. I tillegg får du delta på et

spennende forskningsprosjekt som vil kunne ha betydning for tannleger i framtiden. En mulig

ulempe er at du må sette av tid til prosjektet.

Frivillig deltakelse og mulighet for å trekke sitt samtykke

Det er frivillig å delta i prosjektet. Dersom du ønsker å delta, undertegner du

samtykkeerklæringen på siste side. Du kan når som helst og uten å oppgi noen grunn trekke

ditt samtykke. Dersom du trekker deg fra prosjektet, kan du kreve å få slettet innsamlede

prøver og opplysninger, med mindre opplysningene allerede er inngått i analyser eller brukt i

vitenskapelige publikasjoner. Dersom du senere ønsker å trekke deg eller har spørsmål til

prosjektet, kan du kontakte Dr. Bano Singh (Postdoc, Oral kirurgi og oral medisin, IKO,

Universitetet i Oslo) p.b.singh@odont.uio.no

Hva skjer med informasjonen om deg?

Informasjonen som registreres om deg skal kun brukes slik som beskrevet i hensikten med

studien. Du har rett til innsyn i hvilke opplysninger som er registrert om deg og rett til å få

korrigert eventuelle feil i de opplysningene som er registrert.

Alle opplysningene vil bli behandlet uten navn og fødselsnummer eller andre direkte

gjenkjennende opplysninger. En kode knytter deg til dine opplysninger gjennom en

navneliste.

Prosjektleder har ansvar for den daglige driften av forskningsprosjektet og at opplysninger om

deg blir behandlet på en sikker måte. Informasjon om deg vil bli anonymisert eller slettet

senest fem år etter prosjektslutt.

Hva skjer med prøver som blir tatt av deg?

Prøvene som tas av deg skal oppbevares i en fryser på fakultetet, og fjernes etter prosjektslutt.

Godkjenning

Prosjektet venter på godkjenning av Regional komite for medisinsk og helsefaglig

forskningsetikk.

37

Samtykke til deltakelse i PROSJEKTET

Jeg er villig til å delta i prosjektet

Sted og dato Deltakers signatur

Deltakers navn med trykte bokstaver

Jeg bekrefter å ha gitt informasjon om prosjektet

Sted og dato Signatur

Rolle i prosjektet

If the recipient made the preparation in an incorrect tooth, this decreased the total score with

14 points for tooth 34/35 and 22 points if it was tooth 46. If the neighbor tooth was missing,

this decreased the score with 2 points equivalent to maximum damage.

Singh and Henriksen Scale

Condition 1 Condition 2 Condition 3

Damage to neighbor teeth ( 0-2)

33

34

45

47

Pulpal depth (0-2)

34

35

46M

46D

Gingival height (0-2)

34

35

46M

46D

Occlusal depth (0-2)

35

46

Occlusal width (0-2)

35

46

Buccal extension (0-2)

34

35

46M

46D

Lingual extension (0-2)

34

35

46M

46D

SCORE