Epigenetic influences may explain dental differences in monozygotic twin pairs

The document attached has been archived with permission from the Australian Dental Association (8th Jan 2008). An external link to the publisher’s copy is included.Background: Comparisons between monozygotic (MZ) co-twins have tended to focus on the similarities between their dentitions rather than differences. The aim of this study was to determine the prevalence of discordant expression for simple hypodontia and supernumerary teeth in MZ twin pairs and to explain how phenotypic differences might occur despite their similar genotypes. Methods: Records of 278 pairs of MZ twins, including dental casts and radiographs, were examined and the prevalences of discordant expression for missing upper lateral incisors (ULI) or second premolars (PM2), and of mesiodentes, were determined. Zygosities were confirmed by comparisons of blood markers and DNA. Results: There was evidence of at least one missing ULI or PM2 in 24 of the 278 MZ pairs (8.6 per cent), with 21 of these 24 pairs (87.5 per cent) showing discordant expression. Nine of the 278 MZ pairs (3.2 per cent) displayed evidence of mesiodentes, with eight of these nine pairs (88.9 per cent) being discordant. Conclusion: Our findings show that differences in the expression of missing or extra teeth occur often between MZ co-twins whose genetic make-up predisposes them to simple hypodontia or mesiodentes. We postulate that minor variations in epigenetic events during odontogenesis may account for these distinct differences.GC Townsend, L Richards, T Hughes, S Pinkerton and W Schwerd

Developmental disturbances associated with agenesis of the permanent maxillary lateral incisor

The aim of this study was to characterise the intra and extra-oral phenotype associated with agenesis of the permanent maxillary lateral incisor. We compared three groups: (1) subjects with agenesis of one or both permanent maxillary lateral incisors (n=80); (2) first and second degree relatives of group 1 with no agenesis of the permanent maxillary lateral incisor and (3) subjects with no agenesis of the maxillary lateral incisor or family history of it (n=49). For each of the 201 subjects detailed clinical information was reviewed and panoramic radiographs were analysed. Considering only the sample with unilateral agenesis, microdontia of the contralateral permanent maxillary lateral incisor was significantly more frequent in group 1 (82.4%) than in group 2 (25%) and the control group (2%). This supports the theory that microdontia is a variable expression of the same developmental disturbance that causes tooth agenesis. The absence of third molars occurred more often in group 1 (36.2%) than in groups 2 and 3 (18.6% and 18.9% respectively), confirming that agenesis of third molars was markedly associated with the agenesis of the permanent maxillary lateral incisor. Agenesis of teeth other than third molars was not significantly different among subjects with agenesis of the permanent maxillary lateral incisor and their relatives. The frequencies of supernumerary teeth, permanent maxillary canine impaction, general health condition and minor anomalies were not significantly different between the three groups

Women and Referral to Outpatient Cardiac Rehabilitation: Does the Gender Bias Still Exist? A Meta-Analysis.

Background Cardiovascular disease continues to be among the leading causes of morbidity and mortality among men and women globally. However, research suggests that women are significantly underrepresented in Cardiac Rehabilitation (CR), programs which are shown to reduce recurrent cardiac events and related premature death. However, sex differences in referral rates have not been systematically and quantitatively reviewed. Hence, the objective of the study was to assess whether a significant sex difference exists. Methods This meta-analysis was guided by PRISMA. Scopus, MEDLINE, CINAHL, PsycINFO, PubMed and The Cochrane Library databases were systematically searched for peer-reviewed articles published from July 2000 to July 2011. Titles and abstracts were screened, and the selected full-text articles were independently screened based on pre-defined inclusion/exclusion criteria. Included articles were assessed for quality using STROBE. Meta-analysis was undertaken using Review Manager software. Results Of 623 screened articles, 19 observational studies reporting data for 241,613 participants (80,505 women) were included. In the pooled analysis, women (xx%) were significantly less likely to be referred to CR compared to men (xx%; odds ratio=0.68, 95% confidence interval=0.62-0.74). Conclusion CR referral remains too low for all patients, but is significantly lower for women. Evidence-based interventions to increase referral for all patients, including women have been identified. As recently advocated by the AHA, is time to ensure broader implementation of these strategies.Echo: Improving Women’s Health in Ontario, a former agency of the Ontario Ministry of Health and Long-Term Car

Changes in Smoking and Vaping over 18 Months among Smokers and Recent Ex-Smokers: Longitudinal Findings from the 2016 and 2018 ITC Four Country Smoking and Vaping Surveys

This descriptive study of smokers (smoked at least monthly) and recent ex-smokers (quit for ≤2 years) examined transitions over an 18 month period in their smoking and vaping behaviors. Data are from Waves 1 (W1: 2016) and 2 (W2: 2018) of the ITC Four Country Smoking and Vaping Survey, a cohort study of adult (≥18+) smokers, concurrent users (smoke and vape), and recent ex-smokers from Australia, Canada, England, and the United States (US). Respondents (N = 5016) were classified according to their smoking and vaping status, which resulted in eight subgroups: (1) exclusive daily smokers (2) exclusive non-daily smokers; (3-6) concurrent users (subdivided into four groups by each combination of daily/non-daily smoking and daily/non-daily vaping); (7) ex-smokers who vape; (8) ex-smokers not vaping. The analyses focused first on describing changes between groups from W1 to W2. Second, transition outcomes were assessed based on changes in smoking and vaping between W1 and W2. Transitions focused on smoking were: no change in smoking (continued smoking at the same frequency); decreased smoking; increased smoking; discontinued smoking; relapsed (ex-smokers at W1 who were smoking at W2). Transitions focused on vaping were: initiated vaping; switched from smoking to vaping. Overall, this study found that the vast majority of smokers were smoking 18 months later. Non-daily smokers were more likely than daily smokers to have discontinued smoking (p < 0.0001) and to have switched to exclusive vaping (p = 0.034). Exclusive non-daily smokers were more likely than exclusive daily smokers to have initiated vaping (p = 0.04). Among all W1 daily smokers, there were no differences in discontinued smoking between daily smokers who vaped (concurrent users) and exclusive daily smokers; however, concurrent users were more likely than exclusive daily smokers to have decreased to non-daily smoking (p < 0.001) or to have switched to vaping by W2 (p < 0.001). Among all W1 non-daily smokers, there were no significant differences in increased smoking or discontinued smoking between concurrent users or exclusive smokers. Most ex-smokers remained abstinent from smoking, and there was no difference in relapse back to smoking between those who vaped and those who did not