Institute for Clinical Dentistry (IKO) Amended v.6 28.8..2015/EK
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.
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).
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:
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:
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 Eero Kerosuo
Institute leader Leader of the Research Group
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.
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.
Kundzina, Rita; Kerosuo, Eero N. Utdanner ferske tannleger på løpende bånd. Helgelands Blad [Avis] 2012-11-07 UiT.
Annexes 1-4, see belowAnnex 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 intofour 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.
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.
Rita Kundzina, Napat L Bolstad, Eero Kerosuo
Root canal preparation with ProTaper Next: 3-D analyses by micro computed tomography
Introduction: The objectives ofroot 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.
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
Mohammed Al-Haroni & a PhD stipendiate to be recruited, see:
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.
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.