Institute for Clinical Dentistry (IKO)
Amended v.6 28.8..2015/EK
Research group:
Endodontology and Molecular Oral Microbiology (EMOM).
Leader of the Research Group: Professor Eero Kerosuo, IKO
Strategy, research focus, study aims, plan for external funding
The focus of the group will cover tree centric areas in the field of Endodontology: clinical procedures,
host-microbe interaction and materials related to endodontics.
Clinical Dentistry
The clinical research will focus on treatment of deep carious lesions and eventual pulpal exposures
in adults. A multicenter, randomized clinical trial to compare two materials as a capping agent for
carious pulpal exposures in adult molar is ongoing (www.ClinicalTrials.gov).
Epidemiology
The epidemiological survey in Northern Norway investigate the prevalence of deep carious lesions at
the age of 18 yrs in the entire age cohort born in 1993 and enrolled in the Public Dental Health
Service in Troms county.
The knowledge and attitudes of the dentists’ prevailing methods to treat these conditions will be
examined by a questionnaire comprising all dentists in the Northern Norway. In an ongoing
randomized clinical trial (RCT) a new biomaterial will be tested against the prevailing method as a
capping material of exposed pulps in adults.
Endodontic materials and methods
The group will also focus on the obturation materials in endodontics (including sealers) used in the
root canal filling procedure. The shear bond strength of the material to the root canal wall dentin will be
studied. The micro-CT method will be used to identify the gaps between the material and the root
canal wall and to assess the efficacy of the various root canal irrigation methods. To compare the
materials’ ability to resist microbial leakage, a two-chamber laboratory method is used. Species that
are associated with the re-infection (e.g. Enterococcus faecalis) will deserve as test bacteria. Apart
from the basic culture methods, the microbes are identified by using molecular methods (PCR and
sequencing).
Molecular Oral Microbiology
The aim of our research activity is to understand the host-microbe interaction in health and disease
status of oral and dental tissues. In the last years our research has focused on the presence and
transferability of antibiotic resistance genes among oral bacterial.
Group shall promote research that is relevant to the region's oral health problems i.e. Northern Norway
and the Barents region. The research group is to stimulate national and international applications for
external funding.
Research Group in Endodontology and Oral Microbiology:
Professor Eero Kerosuo, Leader of the Research Group, IKO
Associate Professor Mohammed Al-Haroni, IKO
Associate Professor Napat Boldstad, IKO
Associate Professor Rita Kundzina, IKO
PhD fellow Laura Andriukaitiene, IKO
PhD fellow Lina Stangvaltaite, IKO
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Research collaboration
Tromsø
Associate Professor Xiaobo Song, IMB, UiT
Associate Professor Pål Johansen, IFA, UiT
National
Professor Janne Reseland, IKO, UiO
PhD fellow Anders Verket, IKO, UiO
International
Dr. Lippo Lassila, University of Turku, Finland
Professor Pekka Vallittu, University of Turku, Finland
Dr. Adam Roberts, University College London, UK
Administrative personell
Laila Berg Nilsen, IKO
Current projects:
 Lina Stangvaltaite: ”Deep Caries” in Northern Norway. Principal Investigator: Rita Kundzina.
 Lina Stangvaltaite: Treatment preferences of deep carious lesions in mature teeth. Principal
Investigator: Rita Kundzina
 Lina Stangvaltaite: RCT of pulp capping over carious exposure comparing MTA with calcium
hydroxide. Principal Investigator: Rita Kundzina
 Laura Andriukaitiene: Shear bond strength of four resin based endodontic sealers. Principal
Investigator: Eero Kerosuo
 Laura Andriukaitiene: Microbial leakage of four resin based endodontic sealers. Principal
Investigator: Eero Kerosuo
 Laura Andriukaitiene: Evaluation of adaptation of four root canal sealers to the dentine wall
with and without smear layer using CT
Project Proposals (see Annexes 1-4)
Dental students from the parallel research tract (forskerlinje, FL) are invited to join these projects:
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The effect of photon-induced photoacoustic streaming (PIPS), sonic irrigation and ultrasonic
irrigation of apical debris and smear layer assessed by micro computed tomography and
reduction in bacterial growth. Principal Investigator: Napat Bolstad (Annex 1).
Evaluation of two carrier based obturation techniques by Micro-CT and Two-chamber
bacterial leakage model. Principal Investigator: Rita Kundzina (Annex 2)
Root canal preparation with ProTaper Next: 3-D analyses by micro computed tomography.
Principal Investigator: Rita Kundzina (Annex 3)
Molecular diversity and biological cost and adaptation of oral streptococci to Tn916-like
elements carrying antibiotic resistance genes. Principal Investigator: Mohammed Al-Haroni
(Annex 4).
Tromsø, 11.2. 2015
Claes-Göran Crossner
Institute leader
Eero Kerosuo
Leader of the Research Group
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Publications
Original Articles
Stangvaltaite L, Kundzina R, Bolstad NL, Eriksen HM, Kerosuo E. Deep carious lesions and other consequences
of caries among 18-year-olds at Public Dental Health Service in Northern Norway: A cross-sectional age cohort
study. Acta Odontol Scand. 2014 Dec 22:1-7.
Stangvaltaite L, Kundzina R, Eriksen HM, Kerosuo E. Treatment preferences of deep carious lesions in mature
teeth: Questionnaire study among dentists in Northern Norway. Acta Odontol Scand. 2013 Nov;71(6):1532-7.
Congress Abstracts:
Andriukaitiene, L; Lassila, L V J; Vallittu, PK; Kerosuo, Eero N. Bonding epoxy based sealers to different root
dentine areas with or without the smear layer. 14th Biennial Congress of the European Society of
Endodontology; 2009-09-24 - 2009-09-26 UiT
Stangvaltaite, Lina; Kundzina, Rita; Eriksen, Harald M; Kerosuo, Eero N. The deep caries challenge. Treatment
preferences of deep carious lesions in vital, permanent teeth with closed apexes. The Nordic Young Scientist
Conference in Dentistry 2011; 2011-08-17 - 2011-08-19 UiT
Stangvaltaite, Lina; Kundzina, Rita; Eriksen, Harald M; Kerosuo, Eero N. Treatment preferences of deep carious
lesions in vital permanent mature teeth. Annual Congress of the European Association of Dental Public Health
2012; 2012-11-15 - 2012-11-17 UiT
Stangvaltaite, Lina; Kundzina, Rita; Bolstad, Napat Limchaichana; Eriksen, Harald M; Kerosuo, Eero N. Deep
caries involvements among 18-year-olds in a county of Northern Norway. EADPH meeting; 2013-11-
14 - 2013-11-16 UiT
Kundzina, Rita; Kerosuo, Eero N. MTA Capping on Carious Exposures in Mature teeth. A Randomized Trial. Pulp
Biology and Regeneration Group Symposium 2013 2013-03-24 - 2013-03-26 2013.
Kundzina, Rita; Kerosuo, Eero N. MTA capping on carious exposures in mature teeth: survival analysis of a
randomized clinical trial. 16th European Society of Endodontology Biennial Congress 2013-09-14 - 2013-09-14
2013.
Kundzina, Rita; Kerosuo, Eero N. MTA Capping on Carious Exposures in Mature teeth. A Randomized Trial. Pulp
Biology and Regeneration Group Symposium 2013; 2013-03-24 - 2013-03-26 UiT.
Other:
Kundzina, Rita; Kerosuo, Eero N. Utdanner ferske tannleger på løpende bånd. Helgelands Blad [Avis] 2012-1107 UiT.
Annexes 1-4, see below
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Annex 1. Napat L Bolstad, Rita Kundzina, Xiaobo Song, Eero Kerosuo
The effect of photon-induced photoacoustic streaming (PIPS), sonic irrigation and ultrasonic irrigation of
apical debris and smear layer assessed by micro computed tomography and reduction in bacterial
growth
Introduction: The goal of endodontic treatment is to prevent or heal the apical periodontitis, best achieved by
cleaning and sterilizing the root canal during the chemo-mechanical preparation (Ørstavik and Pitt Ford, 2008).
During the preparation, the debris or remnant of the smear layer maybe sustained in the canal, if not
sufficiently irrigated. Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are the most
common irrigants, and are applied with several techniques: conventional syringe method, substantiated with
sonic, or ultrasonic devices. Photon-induced photo-acoustic streaming (PIPS) is an erbium:YAG laser agitation
technique that has been recently proposed in endodontic irrigation, resulting bigger number of negative
bacterial cultures (Peters et al 2011) and less dentinal debris compared to previous methods (Arslan et al
2014).
Stereo microscopy and scanning electron microscopy (SEM) have been the methods of choice when
assessing the removal of debris by various irrigation protocols, but recently the use of SEM been challenged
(De-Deus et al 2011). Instead, micro computed tomography (micro-CT) has been suggested, but so far only
preliminary studies have been published assessing the efficacy of PIPS with micro-CT (DiVito et al 2012).
Aim: The aim of this study is to evaluate the smear/debris removal efficacy and reduction of bacteria of PIPS
technique in comparison with the conventional syringe irrigation and sonic and ultrasonic techniques.
Methodology: Extracted fully formed apex first molars are scanned by micro-CT to investigate the volumetric
amount of debris or smear at the apical area of the root. Teeth are chemo-mechanically prepared using
conventional syringe irrigation, and further scanned by micro-CT to assess the rest of debris or smear.
Subsequently, the teeth are divided into four groups i) Conventional group (no further irrigation) ii) Sonic
irrigation iii) Ultrasonic irrigation and iv) PIPS. Thereafter all teeth are scanned again, and the additional
removal of the debris or smear is calculated to each method.
To assess the antimicrobial effects of the irrigation methods, another set of extracted teeth are first incubated
with E. faecalis strain, and bacterial samples are taken during and after the irrigation protocol to calculate the
number of negative cultures at the end (Peters et al 2011).
Clinical relevance: If PIPS would be proofed to be equal or superior to prevailing methods in debris/smear
removal and bacterial reduction, its feasibility would facilitate the root canal irrigation process.
References
Arslan H, Capar ID, Saygili G, Gok T, Akcay M. Effect of photon-initiated photoacoustic streaming on removal
of apically placed dentinal debris. Int Endod J. 2014 Jan 23.
De-Deus G, Reis C, Paciornik S. Critical appraisal of published smear layer-removal studies: methodological
issues. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2011 Oct;112(4):531-43.
DiVito E, Peters OA, Olivi G. Effectiveness of the erbium:YAG laser and new design radial and stripped tips in
removing the smear layer after root canal instrumentation. Lasers Med Sci. 2012 Mar;27(2):273-80. doi:
10.1007/s10103-010-0858-x. Epub 2010 Dec 1.
Peters OA, Bardsley S, Fong J, Pandher G, Divito E. Disinfection of root canals with photon-initiated
photoacoustic streaming. J Endod. 2011 Jul;37(7):1008-12.
Ørstavik D., Pitt Ford T., Essential Endodontology: Prevention and Treatment of Apical Periodontitis, 2nd ed.
Oxford, UK: Blackwell Munksgaard Ltd., 2007.
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UiT/IKO/ Research Group: Endodontics, Biomaterials and Oral microbiology
Preliminary study proposal 06.03.2014/RK rev. 7.3.2014 RK/EK
vers2 21.3.14 RK –comments + changes EK25.3.14
Annex 2. Rita Kundzina, Napat L Bolstad, Mohammed Al-Haroni, Eero Kerosuo
Evaluation of two carrier based obturation techniques by Micro- CT and Two-chamber
bacterial leakage model.
Introduction: The objectives of the root canal filling are to prevent the passage of microorganisms and
fluid along the root canal and to fill the entire whole canal system. Several obturation techniques and
materials are employed, but traditionally cold lateral compaction (CLC) of gutta-percha (GP) has been
used as a standard control for comparison of their adaptation to the dentinal wall (Wu & Wesselink,
1933.
The use of Micro-CT has been proved proves to be a powerful nondestructive 3D analysis tool to
visualize the voids and gaps of endodontic materials and their interface with dentin, whilst none of
the tested root filling materials were gap free (Gandolfi et al 2013). From the tested cold methods,
CLC performed best in single rooted anterior teeth (Hammad et al 2009), whereas the vertical (warm
GP) technique has been shown to yield even less voids in curved molars (Naseri et al, 2013).
A carrier based obturation technique, Thermafil, has been shown to yield smallest amount of voids in
filling artificial internal resorption cavities, compared to both CLC and warm vertical techniques
(Keles et al, 2013). Recently new endodontic obturation system, GuttaCore was introduced from the
same company, showing improved feasibility (Beasley et al, 2013). However, there are no studies
assessing either of the carrier based obturation techniques in conventional root canal obturation, and
comparing their adaptation and void formation to CLC.
Aim: The aim of this study is to investigate volume of voids in root canals obturated with two carrier
based obturation techniques, and comparing them with CLC with standard GP.
Methodology: Human molar teeth with fully formed apexes, extracted for reasons not related to this
study, will be stored in 0.1% Chloramine T until used. Teeth will be randomly assigned for 3 different
groups: Thermafil, GuttaCore and CLC with GP. After root canal filling with one of the filling methods
all roots will be stored at 37°C with 100% humidity for about 72 hours to allow the sealer to set
completely. For the 3-dimentional volumetric visualization, analysis and measurements of the gaps
and voids presented in the canal, calculation the percentages of voids and gaps micro-CT scanner and
special software will be used. For bacterial leakage, the method described by Saleh et al (2008) is used.
Clinical relevance: If it could be shown that the more feasible obturation technique also could
provide the adaptation and resistance to bacterial leakage comparable to other methods, it would
add to the simplicity predictability of the obturation method, and thus patient safety and comfort
in endodontic treatments.
References
Beasley RT, Williamson AE, Justman BC, Qian F. Time required to remove GuttaCore, Thermafil Plus, and
thermoplasticized gutta-percha from moderately curved root canals with ProTaper files. J Endod 2013;39:125–128.
Gandolfi MG, Parilli AP, Fini M, Prati C, Dummer PMH. 3D micro-CT analysis of the interface voids associated with
Thermafil root fillings used with AH Plus or a flowable MTA sealer. Int Endod J. 2013:46, 253-263.
Hammad M, Qualtrough A, Silicas N. Evaluation of root canal obturation: a three-dimensional in vitro study. J Endod
2009; 35:541-44.
Keles A, Ahmetoglu F, Uzun I. Quality of different gutta-percha techniques when filling
experimental internal resorptive cavities: A micro-computed tomography study. Aust Dent J. 2013 Oct 9. doi:
10.1111/aej.12043. [Epub ahead of print].
Naseri M, Kangarlou A, Khavid A, Goodinic M. Evaluation of the Quality of four canal obturation techniques using
micro-computer tomography. Iranian Endod. J. 2013,8(3):89-93.
Saleh IM, Ruyter IE, Haapasalo M, Orstavik D. Bacterial penetration along different root canal filling materials in the
presence or absence of smear layer. Int J Endod 2008; 41:32-40.
Wu MK, Wesselink PR. Endodontic leakage studies reconsidered. Part I. Methodology, application and relevance. Int
Endod J. 1993 Jan;26(1):37-43.
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Annex 3.
Rita Kundzina, Napat L Bolstad, Eero Kerosuo
Root canal preparation with ProTaper Next: 3-D analyses by micro computed tomography
Introduction: The objectives of root canal preparation are to: remove remaining pulp tissue, eliminate
micro-organisms, remove debris and shape the root canal(s) so that the root canal system can be
cleaned and filled (European Society of Endodontology, 2006). Despite of the early reports of
instrument fractures, the Nickel-titanium (NiTi) rotary systems have become an essential part for
root canal shaping and outcomes with these instruments are fairly predictable (Parashos & Messer,
2006). The cutting and shaping efficacy of the files can best be assessed by micro computed
tomography (µCT), which offers a nondestructive, high resolution method to study 3-D root canal
geometry before and after the root canal preparation (Peters et al 2001).
Recently ProTaper Next (PTN) system was launched, representing the fifth generation of NiTi rotary
files. Due to the new alloy and manufacturing technology these instruments have enhanced resistance
to cycling fatigue compared with ProTaper Universal (PTU) files (Elnaghy 2014). But so far there is
no published data on the cutting and shaping efficacy of PTN files.
Aim: The aim of this study is to evaluate the cutting and shaping efficacy of PTN files and compare it
to two other rotary file systems frequently used by the dental practitioners in Norway.
Methodology: Human molar teeth with fully formed apexes, extracted for reasons not related to this
study, will be stored in 0.1% Chloramine T until used. The initial canal morphology of all teeth
is determined by µCT scanning. The teeth will then be randomly divided into three groups for
different rotary preparation protocols: PTN, PTU, and BioRace. Differences in dentine volume
removed, canal transportation, and proportions of untouched area will be calculated after the final µCT
scanning (Peters et al 2001).
Clinical relevance: If it could be shown that the files with a high resistance to fracture also provide
the cutting and shaping efficacy comparable to other methods, it would add to the patient safety and
improved outcome of endodontic treatments.
References:
Elnaghy AM. Cyclic fatigue resistance of Pro Taper Next nickel-titanium rotary files.
Int Endod J. 2014 Jan 6 (Epub ahead of print).
European Society of Endodontology. Quality guidelines for endodontic treatment: consensus
report of the European Society of Endontology. Int Endod J. 2006: 39, 921-30.
Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences.
J Endod. 2006 Nov; 32(11):1031-40.
Peters OA, Schonenberger K, Laib A. Effects of four Ni-Ti preparation techniques on root canal
geometry assessed by micro computer tomography. Int Endod J. 2001 Apr:34(3):221-30
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Annex 4.
Mohammed Al-Haroni & a PhD stipendiate to be recruited, see:
http://www.jobbnorge.no/ledige-stillinger/stilling/116512/stipendiat-ved-institutt-for-kliniskodontologi-det-helsevitenskapelige-fakultet
Research project: "Molecular diversity and biological cost and adaptation of oral
streptococci to Tn916-like elements carrying antibiotic resistance genes"
Introduction: Antibiotic resistant-oral streptococcal species have become increasingly common to
isolate in the recent years. Conjugative transposons (cTns) are mobile genetic elements which could
have a panel of antibiotic resistance genes. These mobile genetic elements can move between
different bacterial populations along with the antibiotic resistance genes they encoded for. The cTns,
like Tn916, are so widespread, in terms of both host range and geography.
The aims: The aims of this project are to determine the frequency and diversity of Tn916-like
elements found in oral streptococci and study the persistence of these elements in oral streptococci
and how their biology contribute to the escalating problem of antibiotic resistance in the clinic.
Clinical relevance: Antibiotic resistance in commensal and pathogenic bacteria currently represents
one of the greatest challenges to modern medicine throughout the world. The increase in morbidity
and mortality due to healthcare associated infections is annually increasing. In a recent report on the
problem of antibiotic resistance it was stated that approximately 23 000 patients die annually in the
US from an infection with resistant bacteria. Similarly, the death in the EU attributed to antibiotic
resistant bacteria is approximately 25 000 /per year. In a recent official report from the UK, it is
estimated that by 2050 the total death of patients that infections with antibiotic resistant bacteria
will kill an extra 10 million people a year worldwide – more than currently die from cancer –unless
action is taken. In addition, economic implications for health-care providers, in terms of increased
patient stay in hospitals, isolation procedures and additional medical intervention are increasingly
impinging on the available budgets of healthcare providers. In the US and the EU this has resulted in
extra healthcare costs and productivity losses of at least $20 billions and €1.5 billion, respectively,
each year. There are numerous ways that researchers and clinicians can tackle this problem including
the much needed discovery, or generation, of novel antimicrobials, highlighted by the recent global
10 x ‘20 initiative which aims to produce ten new antimicrobials by 2020.
Relevant publications:
Dhabaan G, AbuBakar S, Cerqueira G, Al-Haroni M, Ping PS, Hassan H. Biological Advantage
Contributes to Explain the Acinetobacter baumannii Resistance to Imipenem (under review).
Starikova I, Al-Haroni M, Werner G, Roberts A, Sørum V, Nielsen K, Johnsen P. Fitness costs of
various mobile genetic elements in Enterococcus faecium and Enterococcus faecalis. J Antimicrob.
Chemother 2013: Dec;68(12):2755-65.
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