Mohammed Al-Haroni

• Field, James; Vital, Sibylle; Murphy, Denis; Dixon, Jonathan; Kavadella, Argyro & Meisha, Dalia [Show all 34 contributors for this article] (2026). Exploring the Capabilities of a Graduating European Dentist: A Multistakeholder View. European journal of dental education. ISSN 1396-5883. doi: 10.1111/eje.70234. Full text in Research Archive Show summary

  In 2026 the Association for Dental Education in Europe (ADEE) Graduating European Dentist (GED) taskforce held an international multi‐stakeholder event that explored opinions, perceived understanding, and clinical expectations around student progress and graduating student capabilities. This paper reports how the event was planned and conducted—and reports the opinions of the stakeholders relating to the importance of various clinical domains, evaluation/assessment metrics and markers when monitoring student progress and student capabilities.

• Shawrob, K.S.M.; Sagen, A.S.; Lunde, Tracy Munthali; Sribasgaran, Biramitha; Ghafoor, Saba & Al-Haroni, M. [Show all 9 contributors for this article] (2026). Mapping Antibiotic Resistance Determinants in Oral Streptococci. Journal of Dental Research. ISSN 0022-0345. doi: 10.1177/00220345261462871. Full text in Research Archive Show summary

  Antibiotic resistance is a global priority in health care. Leveraging thousands of whole-genome sequences, here we reveal the core resistance determinants of oral streptococci, focusing on assessing pattern variability and gene exchange across commensals and pathogens. Genomic information was obtained from the National Center for Biotechnology Information. Determinants of antibiotic resistance were identified using AMRFinderPlus and the Comprehensive Antibiotic Resistance Database. ICEscreen was employed for calling of integrative and conjugative elements. Variability and recombination in penicillin-binding protein sequences were assessed with MMseqs2 and fastGEAR. A total of 2,087 genomes from 15 species were included, representing the mitis, mutans, anginosus, salivarius, and bovis groups. We observed 3,576 hits from 55 unique resistance genes conferring resistance to 11 antibiotic classes. The species with the most resistance determinants per genome against unique antibiotic classes were Streptococcus mitis (2.7), Streptococcus oralis (2.5), Streptococcus parasanguinis (1.9), Streptococcus gallolyticus (1.3), and Streptococcus anginosus (1.2). The 2 latter species also presented the most diverse composition of determinants. Over 1,800 integrative and conjugative elements were predicted across all genomes, with nearly 17% carrying at least 1 antibiotic resistance gene. Penicillin-binding protein variation analyses showed a high diversity in the mitis group. Even though S. mitis and S. oralis composed less than 4% of the genomes included in the analyses, they were recognized as sources of DNA for over a third of recombination events in pbp1a and nearly half for both pbp2b and pbp2x in β-lactam-resistant isolates of Streptococcus pneumoniae . In summary, we show that tetracycline and macrolide resistance were highly abundant and tightly connected to integrative and conjugative elements. Further, recent recombination data in pbp loci show frequent genetic exchange from oral streptococci to β-lactam-resistant S. pneumoniae . Fundamentally, assessing triggers and the dynamics of genetic exchange across species is central to the development of strategies aiming to mitigate the impact of antibiotic resistance.

• Palotie, Ulla; Liukkonen, Mikko; Lingström, Peter; Felszeghy, Szabolcs; Huhtela, Outi & Al-Haroni, Mohammed [Show all 57 contributors for this article] (2026). Reimagining Dental Education: Integrating Digital Technologies for a Global, Digitally Native Generation—A Perspective. European Journal of Dentistry. ISSN 1305-7456. doi: 10.1055/s-0046-1823144. Full text in Research Archive Show summary

  Abstract Digital technologies, such as artificial intelligence (AI), virtual reality (VR), and haptic simulation, are rapidly reshaping oral health education. Traditional phantom head and clinic-based teaching remain essential but no longer suffice alone for digital-native learners or for regulators who increasingly view digital competence as mandatory. Post-COVID evidence suggests immersive and hybrid approaches can enhance motivation, deepen learning, support well-being, and strengthen clinical competence when thoughtfully embedded into curricula. Done well, this integration can foster safer, patient-centered digital care. Sustainability concerns around traditional, resource-intensive methods are also growing; digital tools can reduce material waste and resource use, aligning dental education with the United Nations 2030 Agenda for Sustainable Development. However, access to these innovations is uneven, raising concerns about a digital divide in graduate readiness and patient care. Networks such as the American Dental Education Association (ADEA), the Association for Dental Education in Europe (ADEE), the Haptic and AI Digital Education Network for Excellence and Research (HAiDENERS) show how collaboration and benchmarking can democratize advanced simulation. Together with active communication involving global research bodies and industry, these developments enable a hybrid, evidence-informed, and equitable training ecosystem whose ultimate goal is improved, safer, and more predictable oral health care worldwide.

• Quinn, Barry; Chau, Reinhard Chun Wang; Felszeghy, Szabolcs; Liukkonen, Mikko; Didilescu, Andreea Cristiana & Pasqualini, Damiano [Show all 29 contributors for this article] (2026). Immersive Technologies in Dental Education: Global Adoption Patterns From a 2025 Survey. Journal of Dental Education. ISSN 0022-0337. doi: 10.1002/jdd.70228. Full text in Research Archive Show summary

  Purpose/Objectives Dental education is undergoing a digital transformation, yet the adoption of immersive technologies such as haptic virtual reality (HVR) remains limited. This study aimed to map global adoption trends, barriers, and opportunities for equitable integration of HVR in dental curricula. Methods A 73-item global survey (July–August 2025) was distributed to dental educators across 57 countries via professional networks and social media. The mixed-methods instrument, validated by experts, assessed simulation methods, usage, barriers, and perceptions. Descriptive and exploratory inferential statistics (e.g., one-way ANOVA, Kruskal–Wallis, and chi-square tests) were used to analyze quantitative data, while thematic analysis was used to analyze qualitative responses. Ethical approval was granted by a university ethics review board (No. 13/2023). Results Responses from 130 educators (115 institutions, 57 countries) showed traditional methods (phantom heads, n = 118; benchtop exercises, n = 84) dominating (∼80% clinical training time), while HVR (n = 42, primarily in undergraduate programs) and mixed reality (n = 14, primarily in undergraduate programs) were less prevalent, especially in postgraduate programs (10% HVR use). Barriers in implementing HVR simulators were mainly external, with a lack of resources (66.3%) and resistance from staff and students (21.3%), while personal barriers such as technological limits (9.0%), lack of training (2.2%), and lack of evidence (1.1%) were less common (total n = 89). Countries with higher socioeconomic status were found to use HVR more in undergraduate education than the less well-off countries (p = 0.002). Conclusion(s) Immersive technologies remain underutilized in dental education, particularly at the postgraduate level, creating potential gaps in clinical preparedness. Strategic integration, collaboration, and sustainability-focused adoption may enhance equity and clinical readiness, informing accreditation and policy reforms.

• Tansirichaiya, Supathep; Songsomboon, Kittikun; Wigand, Johannes; Winje, Endre; Chaianant, Nichamon & Leartsiwawinyu, Wasawat [Show all 7 contributors for this article] (2025). Geographic signatures in the oral resistome: a comparative metagenomic analysis of healthy individuals from Thailand and Norway. Journal of Oral Microbiology. 17(1). doi: 10.1080/20002297.2025.2589656. Full text in Research Archive Show summary

  Background The oral cavity is an important yet understudied reservoir of antimicrobial resistance genes (ARGs), potentially shaped by geographic variation in antibiotic usage. Objective To compare the oral resistomes of healthy adults from Thailand and Norway, two countries with contrasting antimicrobial use practices, using shotgun metagenomic sequencing. Design Stimulated saliva samples were collected from healthy adults in Thailand (n = 43) and Norway (n = 50). ARGs were identified with AMRPlusPlus against the MEGARes database, and microbial taxonomy was profiled with KrakenUniq. Diversity metrics, ordination, and clustering analyses assessed resistome and microbiome structures. Results Thai samples exhibited significantly greater ARG richness, evenness, and diversity (p < 0.001), driven by higher abundances of multi-biocide, nucleoside, and copper resistance genes. Norwegian samples were enriched in aminoglycoside, sulfonamide, and quaternary ammonium compound resistance genes. Both cohorts shared core oral genera, but Thai samples showed greater taxonomic richness without differences in overall microbiome diversity. Non-metric multidimensional scaling and PERMANOVA revealed stronger geographic separation for resistomes (R² = 0.639) than microbiomes (R² = 0.382). Co-occurrence networks highlighted structured associations between ARG groups and bacterial genera, suggesting ecological influences beyond taxonomic composition. Conclusions These results reveal distinct geographic signatures in the oral resistome that are not fully explained by microbiome structure, reflecting the influence of local ecological and societal factors, including antimicrobial exposure. The findings highlight the oral cavity as a dynamic ARG reservoir and support its inclusion in regional antimicrobial resistance surveillance to inform public health strategies.

• Frid, Paula Hanna Therese; Halbig, Josefine Mareile; Alstergren, Per; Berstad, Johanna Elisabeth Rykke; Cetrelli, Lena Elisabet & Feuerherm, Astrid Jullumstrø [Show all 15 contributors for this article] (2025). Cytokines in saliva, serum, and temporomandibular joint synovial fluid in children with juvenile idiopathic arthritis: An explorative cross-sectional study. Pediatric Rheumatology. 23. doi: 10.1186/s12969-025-01118-y. Full text in Research Archive Show summary

  Background Proinflammatory cytokines are central to disease mechanisms and important therapeutic targets in inflammatory chronic diseases. This exploratory study aimed to compare cytokine concentrations in saliva, serum, and temporomandibular joint (TMJ) synovial fluid in children with juvenile idiopathic arthritis (JIA) and controls. Methods In this cross-sectional study, we included consecutive children with JIA and TMJ arthritis, planned for a TMJ corticosteroid injection, and non-JIA controls from three different centers in Norway. Data on demographics, disease activity, presence of TMJ arthritis, and medication were obtained. Samples of unstimulated saliva, serum, and TMJ synovial fluid were collected. The amount of recovered synovial fluid in each sample, collected by the push-and-pull technique, was quantified with the hydroxocobalamin method. Cytokine levels were analyzed using Luminex xMAP technology. Results Fifteen patients with JIA and TMJ arthritis (JIA-TMJ) (median age 15.0 (interquartile range (IQR) 11.0–16.0) years) and 34 controls (median age 13.0 (IQR 9.8–15.0) years) were consecutively recruited. Samples of saliva (JIA-TMJ, n = 13, and controls, n = 28), serum (JIA-TMJ, n = 11, and controls, n = 16), and TMJ synovial fluid (JIA-TMJ, n = 8) were collected. In saliva from JIA-TMJ, we found significantly higher levels of the cytokines IL-1β, IL-4, IL-5, IL-9, IL-10, IL-12, IL-13, IL-17, Eotaxin, FGF basic, GM CSF, PDGF bb, TNF, and RANTES, while IP-10 was found in significantly lower concentration compared to controls. In serum, there were no significant differences in these cytokine concentrations between JIA-TMJ and controls. Three TMJ synovial samples fulfilled the strict sampling criteria and were included in the analysis. The level of detected cytokines in TMJ synovial samples was higher in JIA-TMJ compared to controls, as described in a previous Nordic study. Conclusions In this exploratory study, several proinflammatory cytokines were found in higher concentrations in saliva in JIA-TMJ compared to saliva from the controls. No differences were seen in serum between the groups. Some pro- and anti-inflammatory cytokines detected in JIA-TMJ synovial fluid were found in higher concentrations compared to TMJ synovial fluid from healthy adult reference data.

• Leinonen, Kaisa Marika; Leinonen, Jukka; Al-Haroni, Mohammed & Johnsen, Jan-Are Kolset (2025). The Effect of Time Pressure on the Quality of Fillings and Arousal Levels of Dentists. Clinical and Experimental Dental Research. 11(1). doi: 10.1002/cre2.70106. Full text in Research Archive
• Lunde, Tracy Munthali; Tansirichaiya, Supathep; Xue, Ying & Al-Haroni, Mohammed (2025). Evolutionary dynamics of Tn916 in Streptococcus oralis: Fitness cost and persistent metabolic shifts post-acquisition. Archives of Oral Biology. ISSN 0003-9969. 177. doi: 10.1016/j.archoralbio.2025.106317. Full text in Research Archive
• Tansirichaiya, Supathep; Songsomboon, Kittikun; Chaianant, Nichamon; Lertsivawinyu, Wasawat & Al-Haroni, Mohammed Hasan Hussein (2024). Impact of cell lysis treatment before saliva metagenomic DNA extraction on the oral microbiome and the associated resistome. Clinical and Experimental Dental Research. 10(4). doi: 10.1002/cre2.905. Full text in Research Archive Show summary

  Objectives: The human oral microbiome, a complex ecosystem linked to oral and systemic health, harbors a diverse array of microbial populations, including antimicrobial resistance genes (ARGs). As a critical component of the One Health approach to tackle antibiotic resistance, comprehending the oral resistome's composition and diversity is imperative. The objective of this study was to investigate the impact of chemical cell lysis treatment using MetaPolyzyme on the detectability of the oral microbiome, resistome, and DNA quality and quantity.<p> <p>Materials and Methods: Saliva samples were collected from five healthy individuals, and each of the samples was subjected to DNA extraction with and without the treatment with MetaPolyzyme. Through metagenomic sequencing, we analyzed, assessed, and compared the microbial composition, resistome, and DNA characteristics between both groups of extracted DNA. <p>Results: Our study revealed that MetaPolyzyme treatment led to significant shifts in the detectability of microbial composition, favoring Gram‐positive bacteria, notably Streptococcus, over Gram‐negative counterparts. Moreover, the MetaPolyzyme treatment also resulted in a distinct change in ARG distribution. This shift was characterized by an elevated proportion of ARGs linked to fluoroquinolones and efflux pumps, coupled with a reduction in the prevalence of tetracycline and β‐lactam resistance genes when compared with the nontreated group. Alpha diversity analysis demonstrated altered species and ARG distribution without affecting overall diversity, while beta diversity analysis confirmed significant differences in the taxonomical composition and oral resistome between treated and nontreated groups. <p>Conclusions: These findings underscore the critical role of cell lysis treatment in optimizing oral metagenomic studies and enhance our understanding of the oral resistome's dynamics in the context of antimicrobial resistance.

• Al-Mahdi, Rania; Al-Sharani, Hesham; Al-Haroni, Mohammed & Halboub, Esam (2023). Associations of the activity and concentration of carbonic anhydrase VI with susceptibility to dental caries: A systematic review and meta-analysis. Clinical and Experimental Dental Research. doi: 10.1002/cre2.723. Full text in Research Archive Show summary

  Objectives: A number of studies have claimed that carbonic anhydrase VI (CA VI) is associated with dental caries. The aim of this systematic review and meta‐analysis was to systematically review and analyze the literature on the association of CA VI (in terms of concentration and activity) with dental caries.<p> <p>Materials and Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. Relevant search terms were employed to search the following databases: PubMed, Web of Science, Scopus, China National Knowledge Infrastructure (CNKI), and Cochrane Library databases. Eligible publications from inception to August 2022 were included. The relevant records were assessed independently by two reviewers, and a meta‐analysis was performed using RevMan 5.3. <p>Results: Out of 237 relevant records from the initial search, 9 met the criteria for this review. The 9 papers, including 477 participants, were qualitatively analyzed. Seven studies with 411 participants (203 caries‐free) were included in the meta‐analysis on CA VI activity, and 2 studies with 141 participants (71 caries‐free) were included in the meta‐analysis on CA VI concentration. The results showed that CA VI activity was significantly higher among participants with caries than their caries‐free counterparts (standardized mean difference (SMD) = 0.894, 95% confidence interval (CI95%): 0.386 and 1.392; p < 0.001), whereas the CA VI concentration was significantly lower among participants with caries than their caries‐free counterparts (SMD = −0.672, CI95%: −1.011 and −0.332; p < 0.001). <p>Conclusions: This meta‐analysis of a relatively small number of studies suggests that the CA VI concentration is lower and CA VI activity is higher in patients with dental caries than in caries‐free individuals; however, further studies are needed to determine the exact role of CA VI in dental caries.

• Leinonen, Kaisa Marika; Leinonen, Jukka; Bolstad, Napat Limchaichana; Tanner, Tarja; Al-Haroni, Mohammed Hasan Hussein & Johnsen, Jan Are Kolset (2023). Procedure time and filling quality for bulk-fill base and conventional incremental composite techniques—A randomised controlled in vitro trial. Journal of Dentistry. ISSN 0300-5712. 138. doi: 10.1016/j.jdent.2023.104725. Full text in Research Archive Show summary

  Objectives: The aims of this randomised controlled laboratory trial were to determine the procedure time and immediate quality (surface porosity and marginal gaps) of fillings placed using the bulk-fill base technique and the conventional incremental technique in simulated clinical settings.<p> <p>Methods: Forty-two dentists and dental students were randomly allocated to use either the bulk-fill base technique or the conventional incremental technique to fill an identical class II disto-occlusal cavity in a maxillary left first molar typodont tooth. We recorded the time the participants used to fill the cavity and evaluated the surface porosity and marginal gaps on the approximal surfaces of the fillings using a stereomicroscope and specific probes according to the FDI criteria for restoration evaluation. Data were analysed using the Mann–Whitney U, Kruskal–Wallis, and chi-square tests. <p>Results: The median time ± interquartile range was 186 ± 80 s for the bulk-fill base technique and 463 ± 156 s for the conventional incremental technique (p < 0.001). The quality of the fillings was better for the bulk-fill base technique than for the conventional incremental technique (X² = 9.5, p = 0.002). Neither operator experience nor the usual technique of choice were associated with the procedure time or the quality of the fillings. <p>Conclusions: Compared to the conventional incremental technique, the use of the bulk-fill base technique shortened the time to fill a cavity by 59.8 % or 4 min and 36 s, and it improved the immediate surface and marginal quality of the fillings, regardless of the operator’s experience or technique preference. <p>Clinical significance: The use of the bulk-fill base technique instead of the conventional incremental technique leads to significant time-savings when placing large class II composite fillings. Additionally, the use of the bulkfill base technique instead of the conventional incremental technique improves the immediate quality of large class II composite fillings.

• Tousi, Farnoush; Al-Haroni, Mohammed; Lie, Stein Atle & Lund, Bodil (2023). Antibiotic prescriptions among dentists across Norway and the impact of COVID-19 pandemic. BMC Oral Health. 23(1). doi: 10.1186/s12903-023-03380-6. Full text in Research Archive Show summary

  Background The prescription of antibiotics in dental practice contributes significantly to the total use of antibiotics in primary healthcare. This study aimed to evaluate antibiotic prescription in dental practice during the years 2016–2021 in Norway and their relative contribution to national outpatient consumption and to investigate the influence of age, gender, geographic region, and COVID-19. A further aim was to review differences in prescribing patterns to verify effect of governmental strategies to reduce over-prescribing of antibiotics. Methods This register study investigated the national antibiotic prescription between 2016 and 2021. Data was obtained from the Norwegian prescription register, the Norwegian Institute of Public Health and Statistics Norway. The consumption of 12 common antibiotics was measured using WHO defined daily doses (DDDs), DDD per 1000 inhabitants per day (DIDs 1000). Results A total of 6,049,445 antibiotic prescriptions of the 12 investigated compounds were issued in primary care during the study period. Dentists accounted for 942,350 prescriptions corresponding to 15.6% of the total. An overall decrease in the number of prescriptions by health professions other than dentists during the 5 years (IRR = 0.92, 95% CI:0.92–0.93, p < 0.001) was observed. For dentists a slight increase in the number of prescriptions (IRR = 1.01, 95% CI: 1.01–1.01, p < 0.001) was seen over the study period. The increase of antibiotic prescriptions in dentistry was more pronounced during the COVID-19 pandemic. The 4 most prescribed type of antibiotics based on average number of DDDs of the total period 2016–2021 were in descending order; phenoxymethylpenicillin (1,109,150) followed by amoxicillin (126,244), clindamycin (72,565), and metronidazole (64,599). An unexpected finding was that the prescription of the combination compound amoxicillin/clavulanic acid had significantly increased in dentistry during the last 5 years. Geographic, gender, and age differences in the rates of prescriptions were also seen. The data revealed that there are seasonal variations in dental prescriptions. Conclusions Noticeable differences exist in prescribing patterns of antibiotics in the last 5 years. Restricted access to dental care due to COVID-19 may have resulted in increased antibiotic prescribing in dentistry as opposed to an otherwise downward trend. Despite national guidelines there is still a need for improvement of antibiotic stewardship in dentistry and to define effective methods to disseminate information.

• Al-Mahdi, Rania Ali Muhsen; Stangvaltaite-Mouhat, Lina; Aleksejuniene, Jolanta; Stankeviciene, Indre; Tømmerås, Berit & Puriene, Alina [Show all 7 contributors for this article] (2022). Association between Carbonic Anhydrase VI Gene Copy Number Variations and Dental Caries Experience. Caries Research. ISSN 0008-6568. 57(1), p. 67–73. doi: 10.1159/000528749. Full text in Research Archive Show summary

  The current study examined the association between the carbonic anhydrase VI (CA VI) copy number variations (CNVs) and dental caries experience in adults. In total, 202 of 35-72 years old subjects participating in the Lithuanian National Oral Health Survey (LNOHS) agreed to provide saliva samples, thus their data were included in the current study. Information about sociodemographic, environmental, and behavioural determinants was acquired via the self-administered World Health Organisation (WHO) questionnaire. Fluoride levels in the drinking water were recorded based on information provided by water suppliers. Dental caries experience was recorded by one calibrated examiner using the WHO criteria for recording caries on smooth (including proximal, buccal, and oral) or occlusal surfaces. Caries experience was measured as the total number of decayed (D3), missing (M), filled (F) surfaces (D3MFS). DNA was extracted from saliva samples to examine CA VI CNVs using the QX200 droplet digital PCR system. Negative binomial regression and Poisson regression analyses were employed for data analyses. Based on multivariable regression analyses, higher copy number of CA VI were associated with higher caries experience on smooth surfaces (IRR 1.04, 95% CI 1.005 - 1.08) and occlusal surfaces (IRR 1.02, 95% CI 1.003 - 1.04). Positive associations between higher copy number of CA VI and higher caries experience on smooth and occlusal surfaces were found, suggesting that the CA VI coding gene may be associated with caries development. Future studies are needed to validate our results and to examine the underlying mechanisms of such associations.

• Tansirichaiya, Supathep; Winje, Endre; Wigand, Johannes & Al-Haroni, Mohammed (2022). Inverse PCR-based detection reveal novel mobile genetic elements and their associated genes in the human oral metagenome. BMC Oral Health. 22(1). doi: 10.1186/s12903-022-02209-y. Full text in Research Archive Show summary

  The human oral cavity is one of the hotspots harboring multiple mobile genetic elements (MGEs), which are segments of DNA that can move either within bacterial genomes or between bacterial cells that can facilitate the spreading of genetic materials, including antimicrobial resistance genes. It is, therefore, important to investigate genes associated with the MGEs as they have a high probability of dissemination within the bacterial population under selective pressure from human activities. As one-third of oral bacteria are not yet culturable in the laboratory condition, therefore, in this work, it is aimed to detect and identify the genetic contexts of MGEs in the oral cavity through an inverse PCR (IPCR)-based approach on the oral metagenomic. The human oral metagenome was extracted from saliva samples collected from healthy individuals in Tromsø, Norway. The extracted DNA was partially digested with the HindIII restriction enzyme and self-circularized by ligation. DNA primers targeting each MGE were designed to amplify outwards from the MGEs and used for the IPCR on the circularized DNA products. The IPCR amplicons were cloned into a pCR-XL-2-TOP vector, screened, and sequenced. Out of 40 IPCR amplicons, we confirmed and verified the genetic contexts of 11 samples amplified with primers targeting integron gene cassettes (GCs), IS431 composite transposons, and Tn916 conjugative transposons (tet(M) and xis-int). Novel integron GCs, MGEs, and variants of Tn916 conjugative transposons were identified, which is the first report using the IPCR technique to detect the genetic contexts of MGEs in the oral metagenomic DNA.

• Tansirichaiya, Supathep; Goodman, Richard N.; Guo, Xinyu; Bulgasim, Issra; Samuelsen, Ørjan & Al-Haroni, Mohammed [Show all 7 contributors for this article] (2021). Intracellular Transposition and Capture of Mobile Genetic Elements following Intercellular Conjugation of Multidrug Resistance Conjugative Plasmids from Clinical Enterobacteriaceae Isolates. Microbiology spectrum. doi: 10.1128/spectrum.02140-21. Full text in Research Archive Show summary

  Mobile genetic elements (MGEs) are often associated with antimicrobial resistance genes (ARGs). They are responsible for intracellular transposition between different replicons and intercellular conjugation and are therefore important agents of ARG dissemination. Detection and characterization of functional MGEs, especially in clinical isolates, would increase our understanding of the underlying pathways of transposition and recombination and allow us to determine interventional strategies to interrupt this process. Entrapment vectors can be used to capture active MGEs, as they contain a positive selection genetic system conferring a selectable phenotype upon the insertion of an MGE within certain regions of that system. Previously, we developed the pBACpAK entrapment vector that results in a tetracycline-resistant phenotype when MGEs translocate and disrupt the cI repressor gene. We have previously used pBACpAK to capture MGEs in clinical Escherichia coli isolates following transformation with pBACpAK. In this study, we aimed to extend the utilization of pBACpAK to other bacterial taxa. We utilized an MGE-free recipient E. coli strain containing pBACpAK to capture MGEs on conjugative, ARG-containing plasmids following conjugation from clinical Enterobacteriaceae donors. Following the conjugative transfer of multiple conjugative plasmids and screening for tetracycline resistance in these transconjugants, we captured several insertion sequence (IS) elements and novel transposons (Tn<i>7350</i> and Tn<i>7351</i>) and detected the de novo formation of novel putative composite transposons where the pBACpAK-located <i>tet</i>(A) is flanked by <i>Kpn25</i> from the transferred conjugative plasmid, as well as the IS<i>Kpn14</i>-mediated integration of an entire 119-kb, <i>bla</i>_NDM-1-containing conjugative plasmid from <i>Klebsiella pneumoniae</i>.

• Lunde, Tracy Munthali; Hjerde, Erik & Al-Haroni, Mohammed (2021). Prevalence, diversity and transferability of the Tn916-Tn1545 family ICE in oral streptococci. Journal of Oral Microbiology. 13(1), p. 1–12. doi: 10.1080/20002297.2021.1896874. Full text in Research Archive Show summary

  <i>Background</i>: The Tn<i>916</i>-Tn<i>1545</i> family of Integrative Conjugative Elements (ICE) are mobile genetic elements (MGEs) that play a role in the spread of antibiotic resistance genes. The Tn<i>916</i> harbors the tetracycline resistance gene <i>tet</i>(M) and it has been reported in various bacterial species. The increase in the levels of tetracycline resistance among oral streptococci is of great concern primarily due to the abundance of these species in the oral cavity and their ability to act as reservoirs for antibiotic resistance genes.<br><br> <i>Methods</i>: In the current study, we screened 100 Norwegian clinical oral streptococcal isolates for the presence and diversity of the Tn<i>916</i>-Tn<i>1545</i> family. In addition, we investigated the transferability the elements, and the associated transfer frequencies.<br><br> <i>Results</i>: We observed that 21 isolates harboured the Tn916-Tn1545 family and that two of these elements were the novel Tn<i>6815</i> and Tn<i>6816</i>. The most prevalent member of the Tn<i>916</i> -Tn<i>1545</i> family observed in the Norwegian clinical oral streptococcal isolates was the wild type Tn<i>916</i>.<br><br> <i>Conclusion</i>: The detection of other members of this family of ICE and varying transfer frequencies suggests high versatility of the Tn<i>916</i> element in oral streptococci in Norway.

• Drachev, Sergei Nikolaevich; Galieva, Alexandra S.; Yushmanova, TN; Polivanaya, Elena A.; Stangvaltaite-Mouhat, Lina & Al-Mahdi, Rania [Show all 10 contributors for this article] (2021). Restorative treatment decisions for carious lesions: Do Russian dentists and dental students apply minimal intervention dentistry? BMC Oral Health. 21, p. 1–12. doi: 10.1186/s12903-021-01978-2. Full text in Research Archive Show summary

  Background - The concept of minimal intervention dentistry (MID) includes both delayed restorative treatment and conservative caries removal, and is now recognised as an evidence-based approach for dental caries management. In order to determine if dental professionals in Russia are incorporating this concept into their clinical practice, we investigated the restorative treatment decisions of Russian dentists and dental students, and the factors associated with these decisions.<p> <p>Methods - We included 171 general dental practitioners and dental therapists (collectively referred to here as “dentists”) from North-West Russia, and 76 dental undergraduate students from the Northern State Medical University in Arkhangelsk (response rate of 11.5% and 67.9%, respectively). Participants completed a questionnaire, which collected background information (sex, region of work, place of dental school graduation, practice type, years of working experience, working in an urban or rural area, and specialisation in restorative dentistry) and information on restorative treatment decisions for proximal and occlusal carious lesions of permanent teeth. Treatment options in accordance with MID were defined as intervention at dentin level and minimally invasive cavity preparation. Multinomial logistic regression was used for statistical analysis.<p> <p>Results - For the proximal carious lesion, 9.4% of participants said they would employ both MID treatment options; 60.7% said they would choose only one; and 29.9% said they would use neither option. For the occlusal carious lesion, the corresponding figures were 37.2%, 52.1%, and 10.7%. No differences in restorative treatment options were observed among general dental practitioners, dental therapists, and dental students. For the proximal carious lesion, dentists from regions outside Arkhangelsk had 4.15 (95% confidence interval [CI] 1.13–15.27) times higher odds of following one versus both MID treatment options. For the occlusal carious lesion, working experience above 15 years was associated with higher odds of using only one versus both MID treatment options (adjusted odds ratio = 3.04, 95% CI 1.33–6.91). Almost all respondents preferred tooth-coloured materials for restorations; more than 75% chose resin-based composite.<p> <p>Conclusions - The majority of Russian dentists and dental students do not apply the MID concept when treating dental caries in permanent teeth. Clinical protocols on dental caries treatment and dental school curriculums should be updated to place an enhanced focus on evidence-based practice and preventive strategies. Further studies with larger samples of Russian dentists and dental students and alternative methods of recruitment are needed to validate our results.

• Wigand, Johannes; Tansirichaiya, Supathep; Winje, Endre & Al-Haroni, Mohammed (2021). Functional screening of a human saliva metagenomic DNA reveal novel resistance genes against sodium hypochlorite and chlorhexidine. BMC Oral Health. doi: 10.1186/s12903-021-02000-5. Full text in Research Archive Show summary

  Objective - Many sections of the health care system are facing a major challenge making infectious disease problematic to treat; antimicrobial resistance (AMR). Identification and surveillance of the resistome have been highlighted as one of the strategies to overcome the problem. This study aimed to screen for AMR genes in an oral microbiota, a complex microbial system continuously exposed to antimicrobial agents commonly used in dental practice.<p> <p>Materials and methods - As a significant part of the oral microbiome cannot be conventionally cultured, a functional metagenomic approach was chosen. The human oral metagenomic DNA was extracted from saliva samples collected from 50 healthy volunteers in Norway. The oral metagenomic library was then constructed by ligating partially digested oral metagenome into pSMART BAC vector and introducing into Escherichia coli. The library was screened against antimicrobials in dental practices. All resistant clones were selected and analyzed.<p> <p>Results - Screening of the oral metagenomic library against different antimicrobials detected multiple clones with resistance against chlorhexidine, triclosan, erythromycin, tetracycline, and sodium hypochlorite. Bioinformatic analysis revealed both already known resistance genes, including msr, mef(A), tetAB(46), and fabK, and genes that were not previously described to confer resistance, including recA and accB conferring resistance to sodium hypochlorite and chlorhexidine, respectively.<p> <p>Conclusion - Multiple clones conferring resistance to antimicrobials commonly used in dental practices were detected, containing known and novel resistant genes by functional-based metagenomics. There is a need for more studies to increase our knowledge in the field.

• Stangvaltaite-Mouhat, Lina; Puriene, Alina; Aleksejūnienė, Jolanta; Stankeviciene, Indre; Tømmerås, Berit & Al-Haroni, Mohammed (2021). Amylase Alpha 1 Gene (AMY1) Copy Number Variation and Dental Caries Experience: A Pilot Study among Adults in Lithuania. Caries Research. ISSN 0008-6568. doi: 10.1159/000514667. Full text in Research Archive
• Tansirichaiya, Supathep; Moyo, Sabrina John; Al-Haroni, Mohammed & Roberts, Adam P. (2020). Capture of a novel, antibiotic resistance encoding, mobile genetic element from Escherichia coli using a new entrapment vector. Journal of Applied Microbiology. ISSN 1364-5072. p. 1–11. doi: 10.1111/jam.14837. Full text in Research Archive Show summary

  <b><p>Aims</b> Antimicrobial resistance genes (ARGs) are often associated with mobile genetic elements (MGEs), which facilitate their movement within and between bacterial populations. Detection of mobility is therefore important to understand the dynamics of MGE dissemination and their associated genes, especially in resistant clinical isolates that often have multiple ARGs associated with MGEs. Therefore, this study aimed to develop an entrapment vector to capture active MGEs and ARGs in clinical isolates of Escherichia coli. <b><p>Methods and Results</b> We engineered an entrapment vector, called pBACpAK, to capture MGEs in clinical E. coli isolates. It contains a cI‐tetA positive selection cartridge in which the cI gene encodes a repressor that inhibits the expression of tetA. Therefore, any disruption of cI, for example, by insertion of a MGE, will allow tetA to be expressed and result in a selectable tetracycline‐resistant phenotype. The pBACpAK was introduced into clinical E. coli isolates and grown on tetracycline‐containing agar to select for clones with the insertion of MGEs into the entrapment vector. Several insertion sequences were detected within pBACpAK, including IS26, IS903B and ISSbo1. A novel translocatable unit (TU), containing IS26 and dfrA8 was also captured, and dfrA8 was shown to confer trimethoprim resistance when it was cloned into E. coli DH5α. <b><p>Conclusions</b> The entrapment vector, pBACpAK was developed and shown to be able to capture MGEs and their associated ARGs from clinical E. coli isolates. We have captured, for the first time, a TU encoding antibiotic resistance. <b><p>Significance and Impact of the Study</b> This is the first time that a TU and associated resistance gene has been captured from clinical E. coli isolates using an entrapment vector. The pBACpAK has the potential to be used not only as a tool to capture MGEs in clinical E. coli isolates, but also to study dynamics, frequency and potentiators of mobility for MGEs.

• Smith, Andrew; Al-Mahdi, Rania; Malcolm, William; Palmer, Nikolaus; Dahlen, Gunnar & Al-Haroni, Mohammed (2020). Comparison of antimicrobial prescribing for dental and oral infections in England and Scotland with Norway and Sweden and their relative contribution to national consumption 2010-2016. BMC Oral Health. 20. doi: 10.1186/s12903-020-01163-x. Full text in Research Archive Show summary

  <i>Background</i> - Prescribing in dental practice has a relatively small but important contribution to the quantity of antibiotics prescribed in primary care. This study aimed to analyse antibiotic prescribing in dentistry over time (2010–2016) in 4 different Northern European countries and their relative contribution to national outpatients consumption.<p><p> <i>Methods</i> - This retrospective study evaluated the frequency and number of national antibiotic prescriptions written by dentists in England, Scotland, Norway and Sweden. The consumption of such antibiotics was measured using WHO defined daily doses (DDDs), DDDs per 100,000 inhabitants per day (DIDs_100,000).<p><p> <i>Results</i> - A total of more than 27 million prescriptions (27,026,599) archived between 2010 and 2016 from the four countries were analysed. The national contribution of Norwegian dentists to the total primary care prescription during this period was 8%. The corresponding figures for Sweden, Scotland and England were 7, 6, and 8%. Dental contribution to National antibiotic use in all four countries has decreased over the study time period for commonly prescribed antibiotics in dentistry, i.e., the beta-lactams (Phenoxymethyl penicillin/Amoxicillin) and metronidazole. There were less numbers of prescriptions by dentists in Norway and Sweden compared to England and Scotland. Marked differences in some classes of antibiotics were noted with Phenoxymethyl penicillin dominating in Sweden/Norway compared to Amoxicillin and Metronidazole in England/Scotland. In England and Scotland, dentists were the largest prescribers of metronidazole in primary care. Clindamycin prescriptions was higher in Norway and Sweden.<p><p> <i>Conclusion</i> - Noticeable differences exist in prescribing patterns for the management of oral infections. High levels of metronidazole use in England and Scotland also require further analysis. All countries over the study period showed a decrease in total numbers of antibiotics prescribed.

• Frid, Paula; Baraniya, Divyashri; Halbig, Josefine Mareile; Rypdal, Veronika Gjertsen; Songstad, Nils Thomas & Rosén, Annika [Show all 15 contributors for this article] (2020). Salivary Oral Microbiome of Children With Juvenile Idiopathic Arthritis: A Norwegian Cross-Sectional Study. Frontiers in Cellular and Infection Microbiology. 10, p. 1–13. doi: 10.3389/fcimb.2020.602239. Full text in Research Archive Show summary

  Background: The oral microbiota has been connected to the pathogenesis of rheumatoid arthritis through activation of mucosal immunity. The objective of this study was to characterize the salivary oral microbiome associated with juvenile idiopathic arthritis (JIA), and correlate it with the disease activity including gingival inflammation. Methods: Fifty-nine patients with JIA (mean age, 12.6 ± 2.7 years) and 34 healthy controls (HC; mean age 12.3 ± 3.0 years) were consecutively recruited in this Norwegian cross-sectional study. Information about demographics, disease activity, medication history, frequency of tooth brushing and a modified version of the gingival bleeding index (GBI) and the simplified oral hygiene index (OHI-S) was obtained. Microbiome profiling of saliva samples was performed by sequencing of the V1-V3 region of the 16S rRNA gene, coupled with a species-level taxonomy assignment algorithm; QIIME, LEfSe and R-package for Spearman correlation matrix were used for downstream analysis. Results: There were no significant differences between JIA and HC in alpha- and beta-diversity. However, differential abundance analysis revealed several taxa to be associated with JIA: TM7-G1, Solobacterium and Mogibacterium at the genus level; and Leptotrichia oral taxon 417, TM7-G1 oral taxon 352 and Capnocytophaga oral taxon 864 among others, at the species level. Haemophilus species, Leptotrichia oral taxon 223, and Bacillus subtilis, were associated with healthy controls. Gemella morbillorum, Leptotrichia sp. oral taxon 498 and Alloprevotella oral taxon 914 correlated positively with the composite juvenile arthritis 10-joint disease activity score (JADAS10), while Campylobacter oral taxon 44 among others, correlated with the number of active joints. Of all microbial markers identified, only Bacillus subtilis and Campylobacter oral taxon 44 maintained false discovery rate (FDR) < 0.1. Conclusions: In this exploratory study of salivary oral microbiome we found similar alpha- and beta-diversity among children with JIA and healthy. Several taxa associated with chronic inflammation were found to be associated with JIA and disease activity, which warrants further investigation.

• Lunde, Tracy Munthali; Roberts, Adam P. & Al-Haroni, Mohammed (2019). Determination of copy number and circularization ratio of Tn916-Tn1545 family of conjugative transposons in oral streptococci by droplet digital PCR. Journal of Oral Microbiology. 11(1). doi: 10.1080/20002297.2018.1552060. Full text in Research Archive Show summary

  <p><I>Background</I>: Tn916 and Tn1545 are paradigms of a large family of related, broad host range, conjugative transposons that are widely distributed in bacteria and contribute to the spread of antibiotic resistance genes (ARGs). Variation in the copy number (CN) of Tn916-Tn1545 elements and the circularization ratio (CR) may play an important role in propagation of ARGs carried by these elements.</p> <p><I>Objectives and Design</I>: In this study, the CN and CR of Tn916-Tn1545 elements in oral streptococci were determined using droplet digital PCR (ddPCR). In addition, we investigated the influence of tetracycline on the CR of Tn916-Tn1545 elements.</p> <p><I>Results</I>: The ddPCR assay designed in this study is a reliable way to rapidly determine CN and CR of Tn916-Tn1545 elements.</p> <p><I>Conclusions</i>: Our data also suggest that Tn916-Tn1545 elements are generally stable without selective pressure in the clinical oral Streptococcus strains investigated in this study.</p>

• Halboub, Esam; Alzaili, Abdulaziz; Quadri, Mir Faeq Ali; Al-Haroni, Mohammed; Al-Obaida, Mohammad Ibrahim & Al-hebshi, Nezar Noor (2016). Antibiotic prescription knowledge of dentists in kingdom of Saudi Arabia: An online, country-wide survey. Journal of Contemporary Dental Practice. 17(3), p. 198–204. doi: 10.5005/jp-journals-10024-1827. Full text in Research Archive
• Dhabaan, Ghulam Nasser; AbuBakar, Sazaly; Cerqueira, Gustavo Maia; Al-Haroni, Mohammed; Pang, Sui Ping & Hassan, Hamimah (2016). Imipenem treatment induces expression of important genes and phenotypes in a resistant Acinetobacter baumannii isolate. Antimicrobial Agents and Chemotherapy. ISSN 0066-4804. 60(3), p. 1370–1376. doi: 10.1128/AAC.01696-15. Full text in Research Archive
• Mohammed, Marwan; Nerland, Audun Helge; Al-Haroni, Mohammed & Bakken, Vidar (2013). Characterization of extracellular polymeric matrix, and treatment of Fusobacterium nucleatum and Porphyromonas gingivalis biofilms with DNase I and proteinase K. Journal of Oral Microbiology. 5. doi: 10.3402/jom.v5i0.20015. Full text in Research Archive Show summary

  Background : Biofilms are organized communities of microorganisms embedded in a self-produced extracellular polymeric matrix (EPM), often with great phylogenetic variety. Bacteria in the subgingival biofilm are key factors that cause periodontal diseases; among these are the Gram-negative bacteria Fusobacterium nucleatum and Porphyromonas gingivalis. The objectives of this study were to characterize the major components of the EPM and to test the effect of deoxyribonuclease I (DNase I) and proteinase K. Methods : F. nucleatum and P. gingivalis bacterial cells were grown in dynamic and static biofilm models. The effects of DNase I and proteinase K enzymes on the major components of the EPM were tested during biofilm formation and on mature biofilm. Confocal laser scanning microscopy was used in observing biofilm structure. Results : Proteins and carbohydrates were the major components of the biofilm matrix, and extracellular DNA (eDNA) was also present. DNase I and proteinase K enzymes had little effect on biofilms in the conditions used. In the flow cell, F. nucleatum was able to grow in partially oxygenated conditions while P. gingivalis failed to form biofilm alone in similar conditions. F. nucleatum supported the growth of P. gingivalis when they were grown together as dual species biofilm. Conclusion : DNase I and proteinase K had little effect on the biofilm matrix in the conditions used. F. nucleatum formed biofilm easily and supported the growth of P. gingivalis, which preferred anaerobic conditions.

• Nurelhuda, Nazik Mostafa; Al-Haroni, Mohammed Hasan; Trovik, Tordis Agnete & Bakken, Vidar (2010). Caries experience and quantification of streptococcus mutans and streptococcus sobrinus in saliva of Sudanese schoolchildren. Caries Research. ISSN 0008-6568. 44(4), p. 402–407. doi: 10.1159/000316664. Full text in Research Archive
• Al-Hebshi, Nezar Noor Ali; Al-Sharabi, Ali; Shuga-Aldin, Hussein Mohammed; Al-Haroni, Mohammed & Ghandour, Ibrahim (2010). Effect of khat chewing on periodontal pathogens in subgingival biofilm from chronic periodontitis patients. Journal of Ethnopharmacology. ISSN 0378-8741. 132(3), p. 564–569. doi: 10.1016/j.jep.2010.08.051. Full text in Research Archive
• Dabija-Wolter, Gabriela; Cimpan, Mihaela Roxana; Costea, Daniela Elena; Johannessen, Anne Chr.; Sørnes, Steinar & Neppelberg, Evelyn [Show all 9 contributors for this article] (2009). Fusobacterium nucleatum Enters Normal Human Oral Fibroblasts In Vitro. Journal of Periodontology. ISSN 0022-3492. 80(7), p. 1174–1183. doi: 10.1902/jop.2009.090051. Full text in Research Archive Show summary

  Background: Fusobacterium nucleatum, a commensal opportunistic oral bacterium, is capable of invading gingival epithelial cells, but the entrance into human primary oral fibroblast cells has not been documented. This study evaluated the ability of three strains of F. nucleatum (F. nucleatum ssp. nucleatum, F. nucleatum ssp. polymorphum, and F. nucleatum ssp. vincentii) to enter gingival fibroblasts (GFs) and periodontal ligament fibroblasts (PLFs). Methods: GFs and PLFs were cocultured for various periods of time with different strains of F. nucleatum. Scanning and transmission electron microscopy, together with confocal laser scanning microscopy, were used to visualize the entrance and presence of bacteria in host cells. Flow cytometry was performed to compare the load of internalized bacteria in GFs and PLFs exposed for 3 and 5 hours to live F. nucleatum labeled with fluorescein isothiocyanate. Results: All three strains of F. nucleatum were found entering and located in the cytoplasm of GFs and PLFs after 1 hour of exposure. Flow cytometry tests revealed a significant increase in the fluorescent signal, compared to baseline, derived from bacteria internalized in fibroblasts exposed for 3 hours (P <0.001); a further increase was found at 5 hours. The greatest bacterial mass in exposed fibroblasts of both types was of F. nucleatum ssp. polymorphum; the smallest was of F. nucleatum ssp. vincentii. Although not statistically significant, PLFs had a higher bacterial load than corresponding GFs. Conclusion: F. nucleatum was capable of entering GFs and PLFs in a manner that is dependent on the cell type and the bacterial strain.

• Al-Haroni, Mohammed Hasan; Skaug, Nils; Bakken, Vidar & Cash, Phil (2008). Proteomic analysis of ampicillin-resistant oral Fusobacterium nucleatum. Oral Microbiology and Immunology. ISSN 0902-0055. 23(1), p. 36–42. doi: 10.1111/j.1399-302X.2007.00387.x. Full text in Research Archive
• Al-Haroni, Mohammed Hasan (2008). Bacterial resistance and the dental professionals' role to halt the problem. Journal of Dentistry. ISSN 0300-5712. 36(2), p. 95–103. doi: 10.1016/j.jdent.2007.11.007. Full text in Research Archive
• Al-Haroni, Mohammed Hasan; Lygre, Henning & Bakken, Vidar (2008). Antibiotikaresistens hos orale bakterier. Den norske tannlegeforenings Tidende. ISSN 0029-2303. 118(11), p. 704–708. Full text in Research Archive
• Al-Haroni, Mohammed Hasan Hussein & Skaug, Nils (2007). Incidence of antibiotic prescribing in dental practice in Norway and its contribution to national consumption. Journal of Antimicrobial Chemotherapy. ISSN 0305-7453. 59(6), p. 1161–1166. doi: 10.1093/jac/dkm090. Full text in Research Archive
• Al-Hebshi, Nezar Noor Ali; Al-Haroni, Mohammed Hasan Hussein & Skaug, Nils (2006). In vitro antimicrobial and resistance-modifying activities of aqueous crude khat extracts against oral microorganisms. Archives of Oral Biology. ISSN 0003-9969. 51(3), p. 183–188. doi: 10.1016/j.archoralbio.2005.08. Full text in Research Archive
• Al-Haroni, Mohammed Hasan Hussein & Skaug, Nils (2006). Knowledge of prescribing antimicrobials among Yemeni general dentists. Acta Odontologica Scandinavica. ISSN 0001-6357. 64(5; doi: 10.1080/00016350600672829 ), p. 274–280. Full text in Research Archive
• Al-Haroni, Mohammed Hasan Hussein; Skaug, Nils & Al-Hebshi, Nezar Noor Ali (2006). Prevalence of subgingival bacteria resistant to aminopenicillins and metronidazole in dental patients from Yemen and Norway. International Journal of Antimicrobial Agents. ISSN 0924-8579. 27(3), p. 217–223. doi: 10.1016/j.ijantimicag.2005.10. Full text in Research Archive

View all works in NVA

• Sagen, Andreas Solberg; Shawrob, Kazi Shefaul Mulk; Lunde, Tracy Munthali; Sribasgaran, Biramitha; Ghafoor, Saba & Al-Haroni, Mohammed [Show all 9 contributors for this article] (2026). Mobile Genetic Elements Drive Antibiotic Resistance in Oral Streptococci. Full text in Research Archive
• Field, James; Vital, Sibylle; Murphy, Denis; Dixon, Jonathan; Davies, Julia & Kavadella, Argyro [Show all 9 contributors for this article] (2025). The Graduating European Dentist Curriculum Framework: A Multi-Stakeholder View. European journal of dental education. ISSN 1396-5883. doi: 10.1111/eje.70028. Full text in Research Archive Show summary

  In 2025 the Association for Dental Education in Europe (ADEE) Graduating European Dentist (GED) taskforce held an international multi-stakeholder event that undertook a deep-dive into the perceived ideologies underpinning Oral Health Professional (OHP) education. This paper reports how the event was planned and conducted—and reports the challenges that were discussed in relation to delivering OHP education, potential solutions to each challenge, and priorities for which the ADEE GED taskforce should focus its activity. Due to the very collaborative and fruitful nature of this event, ADEE plans to hold further multi-stakeholder meetings across Europe.

• Bolstad, Napat Limchaichana; Al-Haroni, Mohammed & Drachev, Sergei Nikolaevich (2022). Application of minimal intervention dentistry when treating carious lesions. A survey from Northern Norway. Full text in Research Archive
• Al-Haroni, Mohammed (2022). Du har seks milliarder bakterier i munnen. Flere av dem er resistente mot vanlige bakterie­drepende midler. [Journal]. https://forskning.no/. Full text in Research Archive
• Al-Haroni, Mohammed (2021). Odontologiske læresteder bør prioriteres i vaksineprogrammet. Full text in Research Archive
• Al-Haroni, Mohammed; bakken, vidar & Mohammed, Marwan (2009). Characterization of Fusobacterium nucleatum biofilm formation in a hydrodynamic environment. Full text in Research Archive
• Al-Haroni, Mohammed Hasan & Skaug, Nils (2007). Consumption of antibiotics in dentistry assessed by WHO DDD. Full text in Research Archive
• Al-Haroni, Mohammed Hasan; Bakken, Vidar & Skaug, Nils (2006). Fingerprinting of Fusobacterium nucleatum Subspecies Using Proteomic Analysis. Full text in Research Archive
• Al-Haroni, Mohammed Hasan; Bakken, Vidar & Skaug, Nils (2005). Proteomic analysis of β-lactam resistant Fusobacterium nucleatum. Full text in Research Archive
• Al-Haroni, Mohammed Hasan; Skaug, Nils & Al-Hebshi, Nezar Noor Ali (2004). Ampicillin and metronidazole resistant periodontal pathogens in a Yemeni population. Full text in Research Archive
• Mohammed, Marwan Mansoor Ali; Bakken, Vidar; Nerland, Audun Helge & Al-Haroni, Mohammed (2018). Biofilm and planktonic lifestyles of Porphyromonas gingivalis and Fusobacterium nucleatum. Proteomic analysis of bacteria grown as planktonic cells, mono- and dual species biofilm, and characterization of the biofilm extracellular polymeric matrix’. Universitetet i Bergen. ISSN 9788230838167. Full text in Research Archive Show summary

  Periodontitis is one of the most prevalent infectious diseases affecting humans. Periodontitis leads to the destruction of the dental support tissues, which in the terminal stage causes loss of teeth. Periodontitis is biofilm related, a situation where several bacterial species are organized as a community whose resident species differ in many respects from their planktonic (free-living) counterparts. Fusobacterium nucleatum and Porphyromonas gingivalis are among the subgingival bacterial species that play a major role in the dental biofilm formation. F. nucleatum acts as a bridge between early and late colonizers in the dental biofilm and coaggregates with almost all the species that are considered putative periodontal pathogens. P. gingivalis harbors many virulence factors that facilitate colonization and invasion of the periodontal epithelial lining. The main aim of this project was to study in depth and characterize in vitro a dual species biofilm composed of F. nucleatum and P. gingivalis using molecular imaging techniques and proteomics. Furthermore, we wanted to explore the extracellular polymeric substances in the biofilm matrix of the dual and mono-species biofilm, followed by protein identification and analysis of their differential expression. Our results show that proteins and carbohydrates are the major components of the biofilm matrix, and that extracellular (eDNA) is also present. The matrix components are also shown to vary among the species. Proteinase K enzyme showed no effect on the concentration of the eDNA or carbohydrate isolated from the treated matrices. DNase I and proteinase K enzymes had no significant effect on biofilm formation or on mature biofilms under the conditions studied. In the flow-cell biofilm model, F. nucleatum was able to grow in partially oxygenated conditions while P. gingivalis failed to form a biofilm alone under similar conditions but it can grow with F. nucleatum as a dual species biofilm. We identified 542, 93 and 280 proteins from the matrices of F. nucleatum, P. gingivalis, and the dual-species biofilms, respectively. Nearly 70% of all matrix proteins in the dual-species biofilm originated from F. nucleatum, and a majority of these were cytoplasmic proteins, suggesting enhanced lysis of F. nucleatum cells. The proteomic analysis also indicated an interaction between the two species: 22 F. nucleatum proteins showed differential levels between the mono and dual-species extracellular polymeric matrices (EPMs), and 11 proteins (8 and 3 from F. nucleatum and P. gingivalis, respectively) were exclusively detected in the dual-species EPM. Oxidoreductases and chaperones were among the most abundant proteins identified in all three EPMs. The biofilm matrices also contained several known and hypothetical virulence proteins, which can mediate adhesion to the host cells and disintegration of the periodontal tissues. Comparisons between the protein profiles for the two bacterial species grown as a biofilm or in the planktonic state, and when grown as a mono- or dualspecies biofilm, showed significant differences between each setting examined. The most abundant proteins have function such as oxidoreductases, acyltransferases, outer membrane proteins and proteases. Several virulence factors were among the most abundant proteins in both biofilm and planktonic growth conditions. Vitamin B biosynthesis proteins were increased in the biofilm setting compared to the planktonic. When grown in dual species, P. gingivalis showed reduced protein levels in many functions including vitamin biosynthesis, nucleotide biosynthesis, lipid or fatty acid biosynthesis and translation and ribosomal process. These results indicated how growing in a community provides a favorable environment to P. gingivalis and reduces its stress.

• Al-Haroni, Mohammed Hasan; Skaug, Nils & Bakken, Vidar (2007). Antibiotic resistance in oral microbiota : a study on prevalence, molecular analysis, and possible contributing factors in Yemen and Norway. Universitetet i Bergen. ISSN 9788230804322. Full text in Research Archive Show summary

  Worldwide antibiotic resistance among oral microbiota is an increasing problem and information regarding such resistance is completely lacking for Yemen and very limited data is available for Norway. The aims of the current thesis were to (1) disclose the prevalence of ampicillin and metronidazole resistance among selected subgingival microbial species obtained from individuals in Yemen and Norway (paper 1), (2) determine the susceptibility pattern of Fusobacterium nucleatum isolated from Yemen and characterize the aminopenicillins-resistance determinant of F. nucleatum (paper 2), and (3) assess if antimicrobial prescription practices by dentists in Yemen and Norway could possibly contribute to the current prevalence and the emergence of bacterial resistance in these geographically separate locations (papers 3 and 4). Materials: Thirty-four and 21 subgingival plaque samples from Yemen and Norway, respectively, were cultivated on fastidious anaerobic blood agar containing 2 μg/mL of either ampicillin or metronidazole. The bacterial growth from each plate was then screened using DNA-DNA checkerboard hybridization technique for the presence of ampicillin and metronidazole resistance among 18 selected subgingival species (paper 1). Ampicillin-resistant F. nucleatum strains were isolated from Yemen by cultivating subgingival plaque samples on crystal violet erythromycin (CVE) plates supplemented with or without 2 μg/mL ampicillin. The molecular basis of ampicillin resistance among F. nucleatum strains was studied using two-dimensional gel electrophoresis and mass spectrometry (paper 2).The antimicrobials prescription knowledge of Yemeni dentists was investigated by distributing a structured questionnaire to all working dentists in the three major governorates in Yemen. The questionnaire aimed at investigating the therapeutic and prophylactic use of antimicrobials with relevant clinical and non-clinical parameters (paper 3). The Norwegian dentists’ antimicrobial prescription practices were revealed by analyzing aggregated data obtained from the Norwegian Prescription Database (NorPD) on the basis of their total prescriptions of 11 antibiotics issued in 2004 and 2005. Consumptions of these antibiotics in dental practice were measured using the WHO measurement unit, the Defined Daily Dose (DDD) (paper 4). Results: A statistically significant higher resistance to metronidazole and ampicillin among nine and seven species (P <0.05), respectively, was found in Yemeni isolates compared with Norwegian ones. The molecular characterization of ampicillin-resistant F. nucleatum isolates showed that ampicillin-resistant F. nucleatum isolates harboured a class D β-lactamase enzyme. In addition, increased synthesis of two proteins, enolase and ABC transporter ATP-binding proteins, was associated with β-lactamase enzyme production. A sound knowledge of antimicrobials prescription among Yemeni dentists was lacking with a trend of overuse. NorPD data showed antimicrobial prescribing trend in favour of narrow-spectrum penicillins among Norwegian dentists. Conclusions: The findings indicate that high prevalence of resistance among oral bacteria in Yemen maybe a potential threat in the management of dental infections in the region. Antimicrobial overuse by dentists in Yemen could exacerbate the existing dilemma of antimicrobial resistance of oral bacteria. In contrast, the low prevalence of resistance among subgingival species in Norway is most probably a result of the judicious use of antimicrobials, that is, more restrictive prescribing practices in the country. The presence of class D β-lactamase among ampicillin- resistant F. nucleatum strains increases their virulence and cost of treatments as these enzymes might present resistance to several classes of β-lactam antibiotics. Recommendations: Halting resistance development and saving effectiveness of antimicrobials need strict, practical, and feasible approaches. There is an urgent need to formulate an action plan to counter the revealed situation of antimicrobial resistance in Yemen. A proposed strategy to be adopted in the country for the control of antimicrobial resistance should be based on the prevention of communicable diseases and infection control to reduce the need for antimicrobial agents. An antimicrobial resistance surveillance system and a multidisciplinary committee that monitors antimicrobial use in the country should form integral parts of a structured approach to reduce antimicrobial resistance by improving antimicrobial prescribing. Finally, such an effective strategy requires close cooperation and consultation between Yemen and other involved parties, both at national and international levels.

View all works in NVA