Vitrified before and after genome editing via electroporation.

BACKGROUND: Cryopreservation of bovine zygotes allows for a flexible schedule of genome editing via electroporation. However, vitrification-induced cell membrane damage may not only affect embryonic development but also genome mutation. OBJECTIVE: To investigate the effects of vitrification of zygotes before and after electroporation treatments on the development and genome mutation of bovine presumptive zygotes. MATERIALS AND METHODS: In vitro-derived bovine zygotes were electroporated with the CRISPR/Cas9 system immediately (Vitrified-EP) or 2 h after incubation (Vitrified-2h-EP) following vitrification and warming, or electroporated before vitrification (EP-vitrified). RESULTS: The development rates of vitrified-warmed zygotes were significantly lower (p < 0.05) than those of control zygotes that were not vitrified. Moreover, no differences were observed in the mutation rates and mutation efficiency of the blastocysts resulting from electroporated zygotes, irrespective of the timing of electroporation treatment. CONCLUSION: Our results suggest that vitrification before and after electroporation treatments does not affect the genome editing of zygotes.

Editorial - Community Water fluoridation.

Since the discovery of the caries preventive benefits of fluoride, it has been the cornerstone of preventive programs for children and adults. Water fluoridation, the controlled addition of a precise amount of fluoride to community water systems to the level beneficial for dental health, is one of the most effective and safe means to deliver fluoride (McDonagh et al., 2000; National Health and Medical Research Council, 2017). In 1999, the US Centers for Disease Control and Prevention (CDC) named fluoridation of drinking water as one of ten great public health achievements in the 20th Century, alongside vaccination, control of infectious diseases, a decline in death from coronary heart disease and other accomplishments (CDC, 2011). This is a remarkable recognition of the impact of dental conditions and the importance of a dental preventive program.

Outcomes of a co-designed, community-led oral health promotion program for Aboriginal children in rural and remote communities in New South Wales, Australia.

OBJECTIVE: Improving the oral health of Aboriginal children is an Australian priority. Public policy recommends the development of evidence-based, culturally competent oral health promotion programs. Positive health outcomes are more likely for Aboriginal people when programs are co-designed with the community and tailored to local needs. This study aims to determine the impact of a community-led oral health promotion program for Aboriginal children in rural and remote communities. BASIC RESEARCH DESIGN: Consecutive surveys. Baseline data were collected on the oral health of Aboriginal children aged five-12 years in rural and remote communities in Central Northern New South Wales in 2014. Then, an evidence-based oral health promotion program was co-designed with local Aboriginal communities. It included daily toothbrushing, water bottle program, regular application of fluoride varnish, regular distribution of toothbrushes and fluoride toothpaste and dental health education and commenced in 2016 in three schools in the region. In 2018, oral health status and oral hygiene behaviours of participating children were compared against baseline data to evaluate the program. RESULTS: There was a significant reduction in tooth decay, plaque scores and gingivitis. The mean number of teeth affected by tooth decay was 4.13, compared to 5.31 in 2014. An increase was also seen in positive oral hygiene behaviour. CONCLUSIONS: The co-design elements of the program are critical to its success. Engaging local Aboriginal communities to co-design and deliver oral health promotion can reduce the burden of tooth decay experienced by Aboriginal children.

Modulation of the Wnt pathway through inhibition of CLK2 and DYRK1A by lorecivivint as a novel, potentially disease-modifying approach for knee osteoarthritis treatment.

OBJECTIVES: Wnt pathway upregulation contributes to knee osteoarthritis (OA) through osteoblast differentiation, increased catabolic enzymes, and inflammation. The small-molecule Wnt pathway inhibitor, lorecivivint (SM04690), which previously demonstrated chondrogenesis and cartilage protection in an animal OA model, was evaluated to elucidate its mechanism of action. DESIGN: Biochemical assays measured kinase activity. Western blots measured protein phosphorylation in human mesenchymal stem cells (hMSCs), chondrocytes, and synovial fibroblasts. siRNA knockdown effects in hMSCs and BEAS-2B cells on Wnt pathway, chondrogenic genes, and LPS-induced inflammatory cytokines was measured by qPCR. In vivo anti-inflammation, pain, and function were evaluated following single intra-articular (IA) lorecivivint or vehicle injection in the monosodium iodoacetate (MIA)-induced rat OA model. RESULTS: Lorecivivint inhibited intranuclear kinases CDC-like kinase 2 (CLK2) and dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). Lorecivivint inhibited CLK2-mediated phosphorylation of serine/arginine-rich (SR) splicing factors and DYRK1A-mediated phosphorylation of SIRT1 and FOXO1. siRNA knockdowns identified a role for CLK2 and DYRK1A in Wnt pathway modulation without affecting ß-catenin with CLK2 inhibition inducing early chondrogenesis and DYRK1A inhibition enhancing mature chondrocyte function. NF-κB and STAT3 inhibition by lorecivivint reduced inflammation. DYRK1A knockdown was sufficient for anti-inflammatory effects, while combined DYRK1A/CLK2 knockdown enhanced this effect. In the MIA model, lorecivivint inhibited production of inflammatory cytokines and cartilage degradative enzymes, resulting in increased joint cartilage, decreased pain, and improved weight-bearing function. CONCLUSIONS: Lorecivivint inhibition of CLK2 and DYRK1A suggested a novel mechanism for Wnt pathway inhibition, enhancing chondrogenesis, chondrocyte function, and anti-inflammation. Lorecivivint shows potential to modify structure and improve symptoms of knee OA.

Evaluation of a phased pneumococcal conjugate vaccine introduction in Mongolia using enhanced pneumonia surveillance and community carriage surveys: a study protocol for a prospective observational study and lessons learned.

BACKGROUND: Streptococcus pneumoniae causes substantial morbidity and mortality among children. The introduction of pneumococcal conjugate vaccines (PCV) has the potential to dramatically reduce disease burden. As with any vaccine, it is important to evaluate PCV impact, to help guide decision-making and resource-allocation. Measuring PCV impact can be complex, particularly to measure impact on one of the most common and significant diseases caused by the pneumococcus, namely pneumonia. Here we outline the protocol developed to evaluate the impact of 13-valent PCV (PCV13) on childhood pneumonia in Mongolia, and a number of lessons learned in implementing the evaluation that may be helpful to other countries seeking to undertake pneumonia surveillance. METHODS: From 2016 PCV13 was introduced in a phased manner into the routine immunisation programme with some catch-up by the Government of Mongolia. We designed an evaluation to measure vaccine impact in children aged 2-59 months with hospitalised radiological pneumonia as a primary outcome, with secondary objectives to measure impact on clinically-defined pneumonia, nasopharyngeal carriage of S. pneumoniae among pneumonia patients and in the community, and severe respiratory infection associated with RSV and/or influenza. We enhanced an existing hospital-based pneumonia surveillance system by incorporating additional study components (nasopharyngeal swabbing using standard methods, C-reactive protein, risk factor assessment) and strengthening clinical practices, such as radiology as well as monitoring and training. We conducted cross-sectional community carriage surveys to provide data on impact on carriage among healthy children. DISCUSSION: Establishing a robust surveillance system is an important component of monitoring the impact of PCV within a country. The enhanced surveillance system in Mongolia will facilitate assessment of PCV13 impact on pneumonia, with radiological confirmed disease as the primary outcome. Key lessons arising from this evaluation have included the importance of establishing a core group of in-country staff to be responsible for surveillance activities and to work closely with this team; to be aware of external factors that could potentially influence disease burden estimates; to be flexible in data collection processes to respond to changing circumstances and lastly to ensure a consistent application of the pneumonia surveillance case definition throughout the study period.

A small-molecule inhibitor of the Wnt pathway (SM04690) as a potential disease modifying agent for the treatment of osteoarthritis of the knee.

OBJECTIVES: Osteoarthritis (OA) is a degenerative disease characterized by loss of cartilage and increased subchondral bone within synovial joints. Wnt signaling affects the pathogenesis of OA as this pathway modulates both the differentiation of osteoblasts and chondrocytes, and production of catabolic proteases. A novel small-molecule Wnt pathway inhibitor, SM04690, was evaluated in a series of in vitro and in vivo animal studies to determine its effects on chondrogenesis, cartilage protection and synovial-lined joint pathology. DESIGN: A high-throughput screen was performed using a cell-based reporter assay for Wnt pathway activity to develop a small molecule designated SM04690. Its properties were evaluated in bone-marrow-derived human mesenchymal stem cells (hMSCs) to assess chondrocyte differentiation and effects on cartilage catabolism by immunocytochemistry and gene expression, and glycosaminoglycan breakdown. In vivo effects of SM04690 on Wnt signaling, cartilage regeneration and protection were measured using biochemical and histopathological techniques in a rodent acute cruciate ligament tear and partial medial meniscectomy (ACLT + pMMx) OA model. RESULTS: SM04690 induced hMSC differentiation into mature, functional chondrocytes and decreased cartilage catabolic marker levels compared to vehicle. A single SM04690 intra-articular (IA) injection was efficacious in a rodent OA model, with increased cartilage thickness, evidence for cartilage regeneration, and protection from cartilage catabolism observed, resulting in significantly improved Osteoarthritis Research Society International (OARSI) histology scores and biomarkers, compared to vehicle. CONCLUSIONS: SM04690 induced chondrogenesis and appeared to inhibit joint destruction in a rat OA model, and is a candidate for a potential disease modifying therapy for OA.

Understanding Optimum Fluoride Intake from Population-Level Evidence.

Policy on fluoride intake involves balancing caries against dental fluorosis in populations. The origin of this balance lies with Dean's research on fluoride concentration in water supplies, caries, and fluorosis. Dean identified cut points in the Index of Dental Fluorosis of 0.4 and 0.6 as critical. These equate to 1.3 and 1.6 mg fluoride (F)/L. However, 1.0 mg F/L, initially called a permissible level, was adopted for fluoridation programs. McClure, in 1943, derived an "optimum" fluoride intake based on this permissible concentration. It was not until 1944 that Dean referred to this concentration as the "optimal" concentration. These were critical steps that have informed health authorities through to today. Several countries have derived toxicological estimates of an adequate and an upper level of intake of fluoride as an important nutrient. The US Institute of Medicine (IOM) in 1997 estimated an Adequate Intake (AI) of 0.05 mg F/kg bodyweight (bw)/d and a Tolerable Upper Intake Level (UL) of 0.10 mg F/kg bw/d. These have been widely promulgated. However, a conundrum has existed with estimates of actual fluoride intake that exceed the UL without the expected adverse fluorosis effects being observed. Both the AI and UL need review. Fluoride intake at an individual level should be interpreted to inform more nuanced guidelines for individual behavior. An "optimum" intake should be based on community perceptions of caries and fluorosis, while the ultimate test for fluoride intake is monitoring caries and fluorosis in populations.

Effects of Antifreeze Protein Supplementation on the Development of Porcine Morulae Stored at Hypothermic Temperatures.

BACKGROUND: Short-term storage is valuable method to reuse manipulated embryos. OBJECTIVE: The present study evaluated the effects of antifreeze protein (AFP) supplementation on the quality and development of in vitro-produced porcine morulae after short-term storage (24 h). MATERIALS AND METHODS: The morulae were stored with various concentrations of AFP type III for 24 h at 5, 15 and 25C. RESULTS: Supplementation of AFP type III (1.0 microgram per mL) improved the developmental competence of embryos stored at 25C. The proportions of DNA-fragmented nuclei in the blastocysts did not differ between the embryos stored at 25C and the control embryos without storage treatment. However, the developmental competence of embryos stored at hypothermic temperatures decreased relative to that of the control embryos. CONCLUSION: Supplementation of AFP type III (1.0 microgram per mL) maintained the quality of embryos stored at 25C, but did not have beneficial effects on the development of embryos stored at hypothermic temperatures.

Risk indicators for prevalence, extent and severity of periodontitis among rural Indian population aged 35-54 years.

AIMS: This study aimed to identify risk indicators associated with periodontitis and the contribution of each of the indicators towards the prevalence, extent and severity of periodontitis in a rural Indian population. METHODS: A cross-sectional study design was used to collect data according to National Survey of Adult Oral Health Australia guidelines. A multistage stratified random sampling was followed to select 1401 participants, who were in the age group of 35-54 years. The participants were selected from 50 villages belonging to the 5 sub-provinces of 2 Indian districts. Data were collected through face-to-face interviews and oral examination. Statistical analysis was performed using SAS version 9.3. The univariate, bivariate and multivariate analyses were performed to determine the risk indicators of prevalence, extent and severity of periodontitis. Population attributable fraction was estimated for each of the significant risk indicators of prevalence and extent. RESULTS: In this study, factors such as age, education, tobacco chewing and plaque accumulation were significantly associated with the prevalence of periodontitis. Age, socioeconomic status, method of tooth cleaning, alcohol consumption and plaque accumulation were significant risk indicators for generalized periodontitis. Age, tobacco chewing and plaque were associated with severity of periodontitis in the population. CONCLUSION: The rural population had a high prevalence of periodontitis. Sociodemographic factors, poor oral hygiene, tobacco and alcohol were the main risk indicators attributable to periodontitis.

Whole-genome characterisation of G12P[6] rotavirus strains possessing two distinct genotype constellations co-circulating in Blantyre, Malawi, 2008.

Rotavirus A strains detected in diarrhoeal children commonly possess any one of the genotypes G1, G2, G3, G4, and G9, with a recent increase in G12 detection globally. G12P[6] strains possessing short RNA (DS-1-like) and long RNA (Wa-like) migration patterns accounted for 27 % of the strains circulating in Blantyre, Malawi, between 2007 and 2008. To understand how the G12P[6] strains with two distinct genetic backgrounds emerged in Malawi, we conducted whole-genome analysis of two long-RNA and two short-RNA strains. While the former had a typical Wa-like genotype constellation of G12-P[6]-I1-R1-C1-M1-A1-N1-T1-E1-H1, the latter was found to have G12-P[6]-I2-R2-C2-M1-A2-N2-T2-E2-H2: a VP3 gene mono-reassortant on the DS-1-like backbone. Phylogenetic and Bayesian Markov chain Monte Carlo analyses showed that the short-RNA G12P[6] strains were generated around 2006 by reassortment between an African Wa-like G12P[6] strain donating three genes (the VP7, VP4, and VP3 genes) and a G2P[4] strain similar to the one circulating in Thailand or the United States of America that donated the remaining eight genes. On the other hand, the long-RNA strains were generated as a result of reassortment events within Wa-like G12 and non-G12 strains commonly circulating in Africa; only the VP4 gene was from a Malawian G8P[6] strain. In conclusion, this study uncovered the evolutionary pathways through which two distinct G12P[6] strains emerged in Malawi.

Abrupt emergence and predominance in Vietnam of rotavirus A strains possessing a bovine-like G8 on a DS-1-like background.

An apparently single rotavirus A strain possessing a genotype constellation of G8-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 abruptly emerged, caused diarrhoea in children requiring hospitalisation, and increased to reach 27 % of strains detected during the first half of 2015 in Vietnam.

Molecular characterisation of wild-type G1P[8] and G3P[8] rotaviruses isolated in Vietnam 2008 during a vaccine trial.

Rotavirus vaccines work better in developed countries than in developing countries, leading to the question of whether the circulating strains are different in these two settings. In 2008, a clinical trial of the pentavalent rotavirus vaccine was performed in Nha Trang, Vietnam, in which the efficacy was reported to be 64 %. Although samples were collected independently from the clinical trial, we examined faecal specimens from children hospitalised for rotavirus diarrhoea and found that G3P[8] and G1P[8] were co-dominant at the time of the clinical trial. The aim of this study was to explore whether they were divergent from the strains circulating in the developed countries where the vaccine efficacy is high. Two G3P[8] and two G1P[8] strains that were regarded as representatives based on their electropherotypes were selected for full-genome sequencing. The genotype constellation was G1/G3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. All but the VP4 genes, one of which belonged to the emerging P[8]b genotype (OP354-like VP4), clustered into one or more lineages/alleles with the strains circulating in developed countries, with ≥97.5 % nucleotide sequence identity. Additionally, 10 G1 and 12 G3 VP7 sequences as well as 31 VP4 sequences were determined. No amino acid differences were observed between the Vietnamese strains and strains in the developed countries that were likely to have affected the neutralisation specificity of their VP7 and VP4. In conclusion, apart from prevalent P[8]b VP4, virtually no differences were observed between the predominant strains circulating in Vietnam at the time of the clinical trial and the strains in the developed countries; hence, the lower vaccine efficacy was more likely to be due to factors other than strain divergence.

Melatonin Supplementation During In Vitro Maturation and Development Supports the Development of Porcine Embryos.

Melatonin has been reported to improve the in vitro development of embryos in some species. This study was conducted to investigate the effect of melatonin supplementation during in vitro maturation (IVM) and development culture on the development and quality of porcine embryos. In the first experiment, when the in vitro fertilized embryos were cultured with different concentrations of melatonin (0, 10, 25 and 50 ng/ml) for 8 days, the blastocyst formation rate of embryos cultured with 25 ng/ml melatonin (10.7%) was significantly increased (p < 0.05) compared to the control embryos cultured without melatonin (4.2%). The proportion of DNA-fragmented nuclei in blastocysts derived from embryos cultured with 50 ng/ml melatonin was significantly lower (p < 0.05) than that of embryos cultured without melatonin (2.1% vs 7.2%). In the second experiment, when oocytes were cultured in the maturation medium supplemented with different concentrations of melatonin (0, 10, 25 and 50 ng/ml), fertilized and then cultured with 25 ng/ml melatonin for 8 days, there were no significant differences in the rates of cleavage and blastocyst formation among the groups. However, the proportions (2.7-5.4%) of DNA-fragmented nuclei in blastocysts derived from oocytes matured with melatonin were significantly decreased (p < 0.05) compared to those (8.9%) from oocytes matured without melatonin, irrespective of the concentration of melatonin. Our results suggest that supplementation of the culture media with melatonin (25 ng/ml) during IVM and development has beneficial effects on the developmental competence and quality of porcine embryos.

Clustering of risk indicators for periodontal disease: A population-based study.

BACKGROUND: To assess the prevalence of clustering of risk indicators for periodontal disease and association of clustering of the risk indicators with sociodemographic factors and the prevalence of moderate/severe periodontal disease in rural Indian 35-54 year-olds. BASIC RESEARCH DESIGN: A multi-stage cluster random sampling design was used for this population-based cross-sectional study. METHOD: Data were collected through in-person interviews relating to sociodemographic factors and habits. Plaque index and periodontal findings were recorded from oral examination. Clustering of risk indicators such as smoking, tobacco chewing, alcohol and plaque were assessed for association with periodontal disease and various other sociodemographic indicators using logistic regression models. Results: Of 1,401 people approached, 873 completed data; a response rate of 62.3%. Clustering of two or more risk indicators was present in 31% of the population. Prevalence of moderate-severe periodontal disease was 46.6%. Simultaneous presence of two/more risk indicators was strongly associated with sociodemographic factors and periodontal disease. CONCLUSIONS: Clustering of two or more of the factors plaque, smoking, chewing tobacco and alcohol, was strongly associated with periodontitis.

EFFECTS OF ORVUS ES PASTE ON THE MOTILITY AND VIABILITY OF YAK (BOS GRUNNIENS) EPIDIDYMAL AND EJACULATED SPERMATOZOA AFTER FREEZING AND THAWING.

BACKGROUND: The addition of the detergent Orvus ES Paste (OEP) to semen freezing extenders has been observed to improve the post-thaw survival and longevity of spermatozoa from various species but has never been evaluated for yak spermatozoa. OBJECTIVE: This study evaluated the effects of OEP on the post-thaw motility and viability of epididymal and ejaculated yak spermatozoa. MATERIALS AND METHODS: Semen samples were frozen and thawed in semen freezing extender supplemented with 0 %, 0.375 %, 0.75 % or 1.5 % OEP. The motility and viability of frozen-thawed spermatozoa were evaluated before and after 3 h of incubation. RESULTS: The addition of 0.75 % OEP to the freezing extender significantly improved the mean motility and viability values of both the epididymal and ejaculated spermatozoa immediately after thawing, but the beneficial effects on motility disappeared after 3h of incubation. CONCLUSION: Our findings indicate that the addition of 0.75 % OEP is effective for the preservation of yak spermatozoa.

Molecular evolution of the VP7 gene of Japanese G2 rotaviruses before vaccine introduction.

Changes in the prevalence of G2 rotavirus after vaccine introduction are an important issue. However, such changes in a given country should be interpreted in the global context over time. We determined 35 Japanese G2 sequences and compared them with 508 globally collected G2 sequences. The D96N substitution, a substitution known to be associated with an abrupt increase in G2 strains and antigenic changes, emerged in those strains that formed a nascent lineage outside of the currently predominant lineage (sublineage IVa). Further studies are warranted to monitor the potential of their global spread, since they also appeared in Europe and Australia.

Effect of sericin supplementation during in vitro maturation on the maturation, fertilization and development of porcine oocytes.

This study aimed to examine the effects of sericin supplementation during in vitro oocyte maturation on the nuclear maturation, fertilization and development of porcine oocytes. Cumulus-oocyte complexes (COCs) were cultured in maturation medium supplemented with 0 (control), 0.1, 0.5, 1.0, 2.5 or 5.0% sericin and were then subjected to in vitro fertilization and embryo culture. More COCs matured with 1.0% sericin underwent germinal vesicle breakdown and reached metaphase II compared with the control COCs matured without sericin (p < 0.01). The proportions of oocytes with DNA-fragmented nuclei did not differ between the groups, regardless of the sericin level. The total fertilization rate of oocytes matured with 1.0% sericin was higher (p < 0.05) than that of oocytes matured with 0.1%, 2.5% and 5.0% sericin. Supplementation with more than 1.0% sericin decreased the DNA fragmentation index of the blastocysts compared with the control group (p < 0.05). However, the supplementation of the maturation medium with sericin had no beneficial effects on the cleavage, development to the blastocyst stage and the total cell number of the embryos. Our findings indicate that supplementation with 1.0% sericin during maturation culture may improve the nuclear maturation and the quality of the embryos but does not affect blastocyst formation.

Chelation of trace elements in preservation medium influences the quality of boar spermatozoa during liquid preservation at 5°C for 4 weeks.

BACKGROUND: The addition of a metal chelator, ethylenediaminetetraacetic acid (EDTA), to semen extender has the purpose of capturing trace element ions. OBJECTIVE: This study was conducted to evaluate the effects of EDTA on the quality and in vitro fertilisability of liquid-preserved boar spermatozoa. METHODS: In Experiment 1, semen samples were preserved in the semen extender supplemented with 0, 3, 6, or 12 mM of Na-EDTA at 5 degree C for 4 weeks. In Experiment 2, semen samples were preserved in the extender supplemented with 3 mM of Na-EDTA, Ca-EDTA, or Zn-EDTA and without chelator EDTA. RESULTS: When Na-EDTA was used as a chelating substance in the extender, 3 mM was a most suitable concentration for sperm motility and viability after cold preservation. The supplementation of 3 mM Ca-EDTA had advantages regarding sperm motility, viability and plasma membrane integrity. CONCLUSION: Our findings indicate that 3 mM Ca-EDTA is the most suitable metal-chelating substance for the liquid preservation of boar semen.

An opportunity missed: Strengthening health system data on multisystem inflammatory syndrome in children from low- and middle-income countries in Asia.

Background: Multisystem inflammatory syndrome in children (MIS-C) is a severe complication associated with SARS-CoV-2 infection. The clinical epidemiology of MIS-C is not completely understood in low- and middle-income countries (LMICs) due to limited reporting, including in Asia where there was a substantial burden of COVID-19. We aimed to discuss the challenges of diagnosing MIS-C and factors which may cause children from Asian LMICs to have an increased risk of MIS-C. Methods: Not applicable. Results: The burden of MIS-C in Asian LMICs may be disproportionately high due to underlying risk factors, resource-limited health systems, and the increased infectivity and transmissibility of recent SARS-CoV-2 variants. Complex clinical features of MIS-C contributed to missed or delayed diagnosis and treatment, while underlying risk factors including ethnicity, chronic health conditions, and socioeconomic factors may have predisposed children in Asian LMICs to MIS-C. Conclusions: There was a lack of data on the clinical epidemiology of MIS-C in Asian LMICs during the COVID-19 pandemic, despite reports of higher paediatric mortality rates compared to high-income countries. This highlights the need for LMICs to have strong surveillance systems to collect high-quality and timely data on newly emerging complications associated with a pandemic, such as MIS-C. This will lead to rapid understanding of these emerging complications, and inform clinical management, disease prevention and health system planning.

Association between overweight/obesity and dental outcomes in early childhood: Findings from an Australian cohort study.

OBJECTIVES: Oral health is an important part of general health and well-being and shares risk factors, such as poor diet, with obesity. The published literature assessing the association between obesity and oral health in early childhood is sparse and inconsistent. The objective of this study was to investigate associations between overweight/obesity (measured by body mass index) and dental outcomes (caries, plaque index and gingival index) both cross-sectionally and longitudinally, taking account of potential confounding factors, based on data collected at age 2 and age 5 within the Australian Study of Mothers' and Infants' Life Events Affecting Oral Health (SMILE) birth cohort study. METHODS: This study used data from 1174 SMILE participants. Associations between overweight/obesity and dental outcomes were assessed using generalized linear regression models for the modified Poisson family with log link to estimate prevalence ratios. Cross-sectional and longitudinal models were fitted, after minimal and full adjustment for potential confounders. RESULTS: Approximately 12% of the participants were overweight/obese at 2 years and 9% at 5 years. Between 2 and 5 years, the prevalence of caries increased from approximately 4% to 24%, at least mild plaque accumulation increased from 37% to 90% and at least mild inflammation from 27% to 68%. There were no associations between overweight/obesity and the prevalence of dental caries; prevalence ratios (PR) [95% confidence interval (CI)] after adjustment for age and sex were 0.9 (0.3, 2.4) cross-sectionally at 2 years, 1.0 (0.6, 1.5) cross-sectionally at 5 years, and 1.0 (0.6, 1.5) for overweight/obesity at 2 years and caries at 5 years. Prevalence ratios were all around the value of 1 for the other dental outcomes and also after adjustment for additional confounders. CONCLUSIONS: There were no associations between overweight/obesity and dental caries, plaque index or gingival index in this cohort of preschool children. However, associations may emerge as the children become older, and it will be possible to extend analyses to include data collected at age 7 in the near future.