Deliberate foreign body ingestion in patients with underlying mental illness: A retrospective multicentre study.

OBJECTIVE: Deliberate foreign body ingestion (DFBI) is characterised by recurrent presentations among patients with mental health conditions, intellectual disabilities and in prisoners. We aimed to profile the characteristics and evaluate the care of such patients in this study. METHODS: Adult patients with an endoscopic record of attempted foreign body retrieval between January 2013 and September 2020 were identified at three Australian hospitals. Those with a documented mental health diagnosis were included and their standard medical records reviewed. Presentation history, demographics, comorbidities and endoscopic findings were recorded and described. RESULTS: A total of 166 admissions were accounted for by 35 patients, 2/3 of which had borderline personality disorder (BPD). Repetitive presentations occurred in more than half of the cohort. There was an increased trend of hospital admissions throughout the years. At least half of the cohort had a documented mental health review during their admission. An average of 3.3 (2.9) foreign bodies were ingested per single episode. Endoscopic intervention was performed in 76.5% of incidents. The combined Length of stay for all patients was 680 days. CONCLUSION: Deliberate foreign body ingestion in mental health patients is a common, recurring and challenging problem that is increasing in frequency and requires collaborative research to further guide holistic management.

Early childhood caries epidemiology, aetiology, risk assessment, societal burden, management, education, and policy: Global perspective.

BACKGROUND: This paper is a summary of the proceedings of the International Association of Paediatric Dentistry Bangkok Conference on early childhood caries (ECC) held in 3-4 November 2018. AIM: The paper aims to convey a global perspective of ECC definitions, aetiology, risk factors, societal costs, management, educational curriculum, and policy. DESIGN: This global perspective on ECC is the compilation of the state of science, current concepts, and literature regarding ECC from worldwide experts on ECC. RESULTS: Early childhood caries is related to frequent sugar consumption in an environment of enamel adherent, acid-producing bacteria in a complex biofilm, as well as developmental defects of enamel. The seriousness, societal costs, and impact on quality of life of dental caries in pre-school children are enormous. Worldwide data show that ECC continues to be highly prevalent, yet infrequently treated. Approaches to reduce the prevalence include interventions that start in the first year of a child's life, evidence-based and risk-based management, and reimbursement systems that foster preventive care. CONCLUSIONS: This global perspective on ECC epidemiology, aetiology, risk assessment, global impact, and management is aimed to foster improved worldwide understanding and management of ECC.

Caries experience of children in primary schools with long-term tooth brushing programs: A pilot Australian study.

OBJECTIVE: The aim of this study was to evaluate a primary school-based tooth brushing (TB) program conducted in a low socio-economic area of Queensland, Australia, to determine its effectiveness in reducing caries. METHODS: Records kept at the central dental clinic of the district were used to analyse the caries experience (decayed, missing, filled teeth [dmft/DMFT]) and caries prevalence in children from two schools with long-term TB programs (TB) (N=1191) and three Non-TB schools (N=553). The schools were matched by socio-economic indices. RESULTS: Historical records showed that the baseline caries experience in all TB and Non-TB primary schools were similar at each primary school year. After a mean period of 5-9 years of the TB program, the caries experience (mean decayed, missing, filled teeth, dmft/DMFT) and prevalence were lower for TB group than Non-TB group. In the primary dentition, the overall mean dmft (±standard deviation) of TB group (2.53±3.00) was significantly lower than the Non-TB group (3.06±3.30) (P<.001). Similarly, in the permanent dentition, the overall mean DMFT of TB group (0.47±1.05) was reduced significantly compared to the Non-TB group (1.15±1.72) (P<.001). The overall caries prevalence in the TB group was 68% compared to 78% in Non-TB (P<.001). Overall, the mean annual DMFT increments of children in the TB schools were also significantly less compared with children in the Non-TB schools (P<.001). CONCLUSION: A long-term primary school TB program significantly reduced caries experience and caries prevalence in an optimally fluoridated (1-ppm), very low socio-economic district.

A Controlled Study of Pre-Eruptive Intracoronal Resorption and Dental Development.

AIM: To compare the prevalence of PEIR in Australian and Saudi Arabian children and to investigate the relationship of PEIR with dental development. STUDY DESIGN: Panoramic (PAN) radiographs of 842 Australian and 456 Saudi children were screened for PEIR. The dental ages of the children with and without PEIR were assessed from the PAN radiographs using the method of Demirjian and co-workers. RESULTS: The subject prevalence of PEIR was not statistically significant between Australian (2%) and Saudi children (0.6%) (p>0.1). The teeth most commonly affected by PEIR were the mandibular second molars and premolars. Dental impaction was observed in 31% of teeth with PEIR compared to only 0.1% of control teeth (p<0.0001). Children with PEIR showed a mean delay in dental development of 0.54±0.85 years compared with ageand gender-matched controls (p<0.0001). CONCLUSIONS: The present study provides the first evidence that there are no differences in PEIR prevalence between Australian and Saudi populations, and that dental development is significantly delayed in children with PEIR.

Outdoor, indoor, and personal black carbon exposure from cookstoves burning solid fuels.

Black carbon (BC) emissions from solid fuel combustion are associated with increased morbidity and mortality and are important drivers of climate change. We studied BC measurements, approximated by particulate matter (PM2.5 ) absorbance, in rural Yunnan province, China, whose residents use a variety of solid fuels for cooking and heating including bituminous and anthracite coal, and wood. Measurements were taken over two consecutive 24-h periods from 163 households in 30 villages. PM2.5 absorbance (PMabs ) was measured using an EEL 043 Smoke Stain Reflectometer. PMabs measurements were higher in wood burning households (16.3 × 10(-5) /m) than bituminous and anthracite coal households (12 and 5.1 × 10(-5) /m, respectively). Among bituminous coal users, measurements varied by a factor of two depending on the coal source. Portable stoves (which are lit outdoors and brought indoors for use) were associated with reduced PMabs levels, but no other impact of stove design was observed. Outdoor measurements were positively correlated with and approximately half the level of indoor measurements (r = 0.49, P < 0.01). Measurements of BC (as approximated by PMabs ) in this population are modulated by fuel type and source. This provides valuable insight into potential morbidity, mortality, and climate change contributions of domestic usage of solid fuels.

Indoor concentrations of nitrogen dioxide and sulfur dioxide from burning solid fuels for cooking and heating in Yunnan Province, China.

The Chinese national pollution census has indicated that the domestic burning of solid fuels is an important contributor to nitrogen dioxide (NO2 ) and sulfur dioxide (SO2 ) emissions in China. To characterize indoor NO2 and SO2 air concentrations in relation to solid fuel use and stove ventilation in the rural counties of Xuanwei and Fuyuan, in Yunnan Province, China, which have among the highest lung cancer rates in the nation, a total of 163 participants in 30 selected villages were enrolled. Indoor 24-h NO2 and SO2 samples were collected in each household over two consecutive days. Compared to smoky coal, smokeless coal use was associated with higher NO2 concentrations [geometric mean (GM) = 132 µg/m(3) for smokeless coal and 111 µg/m(3) for smoky coal, P = 0.065] and SO2 [limit of detection = 24 µg/m(3) ; percentage detected (%Detect) = 86% for smokeless coal and 40% for smoky coal, P < 0.001]. Among smoky coal users, significant variation of NO2 and SO2 air concentrations was observed across different stove designs and smoky coal sources in both counties. Model construction indicated that the measurements of both pollutants were influenced by stove design. This exposure assessment study has identified high levels of NO2 and SO2 as a result of burning solid fuels for cooking and heating.

Effects of water fluoridation on caries experience in the primary dentition in a high caries risk community in Queensland, Australia.

OBJECTIVES: In December 2008, artificial water fluoridation was introduced for the first time to the Logan-Beaudesert district in the state of Queensland, Australia. The aim of this study was to evaluate the effects of water fluoridation in the primary dentition in this community after a period of 36 months. METHODS: Children aged 4-9 years with clinical examinations and bitewing radiographs (BWs) taken before water fluoridation (pre-F) were randomly selected as comparison controls for age matched children who had been exposed to a mean period of 36 months of water fluoridation (post-F). A total of 201 sets of pre-F BWs from children (mean age 6.95 ± 1.05 years) and 256 sets of post-F BWs from children (mean age 7.19 ± 1.23 years) attending schools in the district were randomly selected. Caries experience in the primary dentition was determined as decayed, missing or filled teeth/surfaces (dmft/dmfs). RESULTS: The caries prevalence for the pre-F group was 87% compared to 75% in the post-F group (Odds ratio (OR): 0.44, 95% CI: 0.27-0.72). Overall, there was a 19 percent reduction of mean dmft from 4.54 in the pre-F group to 3.66 in the post-F group (p = 0.005). After fluoridation, the dmfs was reduced from 6.68 to 5.17 (p = 0.0056). The distal surfaces of maxillary first primary molars experienced the greatest reduction (26%) in caries experience after water fluoridation (p < 0.001). CONCLUSIONS: After only 36 months of water fluoridation there was a significant drop in caries prevalence from 87 to 75% and a 19% reduction in caries experience in a community with one of the highest caries rates in Australia.

Association of erosion with timing of detection and selected risk factors in primary dentition: a longitudinal study.

OBJECTIVE: The aims of this study were to determine the prevalence of erosion in a birth cohort at 24, 36, and 48 months and to investigate risk factors for erosion. METHODS: One hundred and fifty-four children from a birth cohort were followed at 24, 36, and 48 months of age. RESULTS: Of the 154 children examined, 0% (0/154), 7% (11/154), and 28% (40/154) had erosion detected for the first time at 24, 36, and 48 months, respectively (P < 0.001). A cumulative total of 51 (33%) children and 256 (8%) teeth had erosion by the age of 48 months. There were no significant associations between erosive lesions first detected at 36 months and oral hygiene behaviour, medical conditions, or dietary habits reported at the 24- or 36-month examinations (all P > 0.05). In contrast, erosive lesion first detected at 48 months was positively associated with the use of a feeding bottle reported at the 36-month examination (P = 0.026). CONCLUSIONS: The prevalence of dental erosion in young children increased with age, with clinically detectable lesions forming between 24 and 36 months of age. Erosive lesions first detected at 48 months were positively associated with the use of a feeding bottle reported at 36 months.

Bacterial colonization, enamel defects and dental caries in 4-6-year-old mono- and dizygotic twins.

BACKGROUND: Knowledge of the genetic and environmental influences in caries aetiology has relevance for preventive dentistry. AIMS: This classical twin study compared concordance of mutans streptococci (MS) and lactobacilli (LB) colonization, enamel defects, and caries in a cohort of 4-6-year-old mono- (MZ) and dizygotic (DZ) twin pairs. DESIGN: The twins were examined for prevalence and concordance of enamel opacities and hypoplasia, oral counts of MS and LB, and dental caries. Bacterial counts were assessed using a commercial microbiological kit. RESULTS: Thirty-four MZ and 50 DZ twins (mean gestational age 35.0 ± 2.4 weeks, and birthweight 2.4 ± 0.6 kg) were examined. There were no statistically significant differences between MZ and DZ twins in the prevalence of MS, LB, and enamel hypoplasia. Concordance rates for MS and LB presence and prevalence of enamel defects within MZ and DZ twin pairs were not significantly different. There were more children with caries in DZ compared with MZ twins (18% vs 3%, P = 0.0029), most likely due to increased daily frequency of sugar consumption and less toothbrushing. CONCLUSIONS: Concordance data from MZ and DZ twins did not demonstrate any statistically significant difference in susceptibility for enamel defects and colonization of MS and LB.

Genetic, epigenetic, and environmental influences on dentofacial structures and oral health: ongoing studies of Australian twins and their families.

The Craniofacial Biology Research Group in the School of Dentistry at The University of Adelaide is entering an exciting new phase of its studies of dental development and oral health in twins and their families. Studies of the teeth and faces of Australian twins have been continuing for nearly 30 years, with three major cohorts of twins recruited over that time, and currently we are working with twins aged 2 years old to adults. Cross-sectional data and records relating to teeth and faces of twins are available for around 300 pairs of teenage twins, as well as longitudinal data for 300 pairs of twins examined at three different stages of development, once with primary teeth, once at the mixed dentition stage, and then again when the permanent teeth had emerged. The third cohort of twins comprises over 600 pairs of twins recruited at around birth, together with other family members. The emphasis in this third group of twins has been to record the timing of emergence of the primary teeth and also to sample saliva and dental plaque to establish the timing of colonization of decay-forming bacteria in the mouth. Analyses have confirmed that genetic factors strongly influence variation in timing of primary tooth emergence. The research team is now beginning to carry out clinical examinations of the twins to see whether those who become colonized earlier with decay-forming bacteria develop dental decay at an earlier age. By making comparisons within and between monozygotic (MZ) and dizygotic (DZ) twin pairs and applying modern molecular approaches, we are now teasing out how genetic, epigenetic, and environmental factors interact to influence dental development and also oral health.

A longitudinal case-control study of caries development from birth to 36 months.

BACKGROUND/AIMS: The aim of this longitudinal case-control study was to investigate variables associated with caries development from birth to 36 months. METHODS: Children (n = 1,017) who were followed up every 6 months from birth to 36 months were grouped into those that developed caries by age 30 and 36 months, respectively, and compared with children without caries. RESULTS: By 30 months (n = 608) there were 24 children (4%) who had caries and an additional 23 developed first caries at 36 months (n = 552), giving a total prevalence of 47 children with caries (9%) at 36 months. Children who showed caries by 30 months were more likely to be mutans streptococci (MS) colonised by 18 months (p = 0.001) compared to those who developed caries at 36 months, and showed the following variables: MS counts of >10(5) CFU/ml at 12 months (p = 0.005), missing enamel (p = 0.001), sugar in pacifier at 18 months (p = 0.02), child sleeping next to mother at 6, 18 and 24 months (p = 0.001 to p = 0.02), and exposure to household cigarette smoke at 24 months (p = 0.02). Caries at 36 months was associated with pregnancy problems (p = 0.024), mother having dental cavitations (p = 0.001) and MS presence at 36 months (adjusted odds ratio, AOR = 0.1, p = 0.01 for counts <10(5) CFU/ml). Caries at both 30 and 36 months was associated with MS presence at 18 months (AOR = 6.3, p = 0.005 and AOR = 4.9, p = 0.01). CONCLUSIONS: Children who developed caries by 30 months are colonised by MS at younger ages and with higher MS counts compared with children who develop caries at 36 months.

A randomised, controlled clinical trial comparing chlorhexidine gel and low-dose fluoride toothpaste to prevent early childhood caries.

OBJECTIVES. This randomised, controlled trial compared the effectiveness of 0.12% chlorhexidine (CHX) gel and 304% fluoride toothpaste to prevent early childhood caries (ECC) in a birth cohort by 24 months. METHODS. The participants were randomised to receive either (i) twice daily toothbrushing with toothpaste and once daily 0.12% CHX gel (n = 110) or (ii) twice daily toothbrushing with toothpaste only (study controls) (n = 89). The primary outcome measured was caries incidence and the secondary outcome was percentage of children with mutans streptococci (MS). All mothers were contacted by telephone at 6, 12, and 18 months. At 24 months, all children were examined at a community dental clinic. RESULTS. At 24 months, the caries prevalence was 5% (3/61) in the CHX and 7% (4/58) in the controls (P = 0.7). There were no differences in percentages of MS-positive children between the CHX and control groups (54%vs 53%). Only 20% applied the CHX gel once daily and 80% less than once daily. CONCLUSIONS. Toothbrushing using 304% fluoride toothpaste with or without the application of chlorhexidine gel (0.12%) reduces ECC from 23% found in the general community to 5-7%. The lack of effect with chlorhexidine is likely to be due to low compliance.

A controlled, longitudinal study of home visits compared to telephone contacts to prevent early childhood caries.

BACKGROUND: Home visits (HV) provide excellent opportunities for health promotion. AIM: This longitudinal study compared the effects of HV and telephone contacts (TC) in preventing early childhood caries (ECC) and colonisation of mutans streptococci (MS) and lactobacilli (LB) from 0 to 24 months. DESIGN: A total of 325 children were recruited from community health centres at mean age of 42 days, and randomly assigned to receive either HV or TC. A total of 188 children completed three, 6 monthly HV, and another 58 had three, 6 monthly TC. An additional 40 age-matched children from childcare facilities served as reference controls (RC). At 24 months, all groups were examined at a community dental clinic. RESULTS: At 24 months, three HV children of 188 (1.5%) had caries, compared to four TC of 58 (6.8%) and nine RC of 40 (22.5%) (P < 0.001 for HV versus RC; P = 0.05 for HV versus TC and P = 0.03 for TC versus RC). There were also more children with MS in the TC (47%) and RC (35%) compared to HV (28%) group (P = 0.01 and P = 0.02). CONCLUSIONS: Home visits and telephone contacts conducted 6 monthly from birth are effective in reducing ECC prevalence by 24 months.

A longitudinal study comparing mutans streptococci and lactobacilli colonisation in dentate children aged 6 to 24 months.

This longitudinal study aimed to investigate variables associated with colonisation of mutans streptococci (MS) compared with lactobacilli (LB) colonisation in a cohort of children (n = 214) from the time of first tooth eruption at approximately 6 months until 24 months of age. Repeated plaque and salivary samples were collected from the same infants at 6, 12, 18 and 24 months and assayed for MS and LB using a microbiological culture kit. Children having both MS and LB increased from 4% at 6 months to 13% at 12 and 18 months to 20% at 24 months (p = 0.004). LB presence at 6 months was correlated with MS presence at 12, 18 and 24 months (r = 0.21 to r = 0.46, p = 0.02), while MS presence at 6 months correlated with LB presence at all other times (r = 0.19 to r = 0.31, p = 0.03). At 6 and 12 months, the key variables for MS colonisation included unrestored dental cavities in the mother (p = 0.03), mother not persisting with toothbrushing (p = 0.001) and bottle taken to bed at night (p = 0.033), while the only significant variable for LB colonisation was natural birth (p = 0.01). At 24 months, the significant variables for MS colonisation were condiments added to pacifier (p = 0.022) and child being uncooperative for toothbrushing (p = 0.025), while the significant variables for LB colonisation were pregnancy problems (p = 0.028) and child being uncooperative for toothbrushing (p = 0.013). The ages 6-12 months thus represent a time period when key variables may be controlled to reduce MS and LB colonisation.

Mutans streptococci and lactobacilli colonization in predentate children from the neonatal period to seven months of age.

BACKGROUND/AIMS: The aim of this study was to investigate the colonization of mutans streptococci (MS) and lactobacilli (LB) in predentate children from the neonatal period to 7 months. METHODS: A total of 957 mother-and-child pairs were recruited from birth and followed up at 7 months. The 283 children who did not have erupted teeth at the second visit were included in the study. Oral mucosal swabs were taken, and the presence of MS and LB was determined using a commercial microbiological culture kit. RESULTS: At mean ages of 34 days and 7 months, 9 and 11% of the infants, respectively, showed the presence of MS. In contrast, LB presence increased from 24 to 47% (p < 0.0001). MS presence in the neonatal period was associated with maternal MS counts of >10(5) CFU/ml (p = 0.05), while LB presence was associated with natural birth (p = 0.03) and maternal LB presence (p = 0.02). At 7 months, MS presence was associated with maternal MS counts (p = 0.02) and LB counts of >10(5) CFU/ml (p = 0.007). Additional predictors of MS presence at 7 months were a child's MS counts of >10(5) CFU/ml at the neonatal visit (p = 0.019) and nighttime bottle feeding (p = 0.024). LB presence at 7 months was associated with maternal LB (p < 0.001) and MS presence (p = 0.02). CONCLUSIONS: MS and LB can be detected by culture in the oral cavity as early as 34 days after birth. Their infection rates increase to 11 and 47%, respectively, by the time the children reach the end of the predentate stage of oral development.

Environmental, maternal, and child factors which contribute to early childhood caries: a unifying conceptual model.

OBJECTIVES: Although the general pathways connecting the external social environment and child risk factors of early childhood caries (ECC) have been previously identified, the maternal and other links to ECC are not well understood. The aim of this paper is to propose a unifying conceptual model that ties together the broad social environmental, maternal, and child factors that are commonly associated with ECC. METHODS: The aetiological factors of ECC are first reviewed individually to demonstrate their connections with ECC risk followed by presentation of the unifying conceptual model. RESULTS: In severe ECC cases, there is usually a background of social disadvantage associated with low socioeconomic status, ethnicity or immigrant status, and low maternal educational level. These factors are commonly associated with economic and familial stresses which may in turn result in maternal psychological distress. The distress may be compounded by difficult temperaments of the children and can lead to dysfunctional parenting behaviours that place a child at risk for ECC. CONCLUSIONS: The proposed conceptual model provides a framework that connects the social, psychological, and behavioural mediating factors involved in ECC. It demonstrates that the causative pathways involved are best explored using a combination of quantitative and qualitative research.

The Queensland Birth Cohort Study for Early Childhood Caries: Results at 7 Years.

AIMS: This study investigated caries predictors in 378 children remaining from a birth cohort of 1,052 at 7 y and compared the efficacy of home visits (HVs) and telephone contacts (TCs) for early childhood caries (ECC) prevention. METHODS: The HVs or TCs were made at ages 6, 12, 18, 30, and 42 mo with annual dental clinic examinations at ages 2 to 7 y. At every visit, the parents completed validated questionnaires regarding the children's family, medical, dental, and dietary histories. RESULTS: The caries prevalence increased from 2% and 6% at ages 2 and 3 y to 15%, 33%, 42%, and 52% at ages 4 to 7 y. The mean caries experience (decayed, missing, and teeth extracted due to caries) of the total cohort increased from 0.1 ± 0.5 at age 2 y to 0.2 ± 1.1 at 3 y, 0.5 ± 1.6 at 4 y, 1.1 ± 2.4 at 5 y, 1.6 ± 2.6 at 6 y, and 2.0 ± 2.7 at 7 y. The prevalence of mutans streptococci (MS) in the total cohort at years 2 to 7 was 22%, 36%, 42%, 42%, 39%, and 44%, respectively. MS was strongly correlated with caries prevalence for all years (all P < 0.001). Statistical modeling employing the generalized estimating equations identified caries predictors as holding a Health Care Card (low socioeconomic status) (P = 0.009; odds ratio [OR] = 2.05; confidence interval [CI]: 1.20-3.52), developmental defects of enamel (DDEs) (P < 0.001; OR = 1.09; CI: 1.05-1.14), and MS counts ≤105/mL (P = 0.001; OR = 1.63; CI: 1.24-2.14). By contrast, HVs were more protective than TCs for caries (P = 0.008; OR = 0.42; CI: 0.22-0.80). CONCLUSIONS: This study provides prospective, clinical evidence that MS, DDEs, and low socioeconomic status are strongly correlated with early childhood caries and that HVs are more efficacious than TCs in ECC prevention. KNOWLEDGE TRANSFER STATEMENT: This 7-y birth cohort study provides longitudinal clinical evidence that mutans streptococci, developmental defects of enamel, and low socioeconomic status are key risk indicators of early childhood caries.

Increased traffic exposure and negative birth outcomes: a prospective cohort in Australia.

BACKGROUND: Pregnant women exposed to traffic pollution have an increased risk of negative birth outcomes. We aimed to investigate the size of this risk using a prospective cohort of 970 mothers and newborns in Logan, Queensland. METHODS: We examined two measures of traffic: distance to nearest road and number of roads around the home. To examine the effect of distance we used the number of roads around the home in radii from 50 to 500 metres. We examined three road types: freeways, highways and main roads. RESULTS: There were no associations with distance to road. A greater number of freeways and main roads around the home were associated with a shorter gestation time. There were no negative impacts on birth weight, birth length or head circumference after adjusting for gestation. The negative effects on gestation were largely due to main roads within 400 metres of the home. For every 10 extra main roads within 400 metres of the home, gestation time was reduced by 1.1% (95% CI: -1.7, -0.5; p-value = 0.001). CONCLUSIONS: Our results add weight to the association between exposure to traffic and reduced gestation time. This effect may be due to the chemical toxins in traffic pollutants, or because of disturbed sleep due to traffic noise.

Enamel hypoplasia in the primary dentition of monozygotic and dizygotic twins compared with singleton controls.

BACKGROUND: The study of enamel hypoplasia (EH) and opacity in twins provides insights into the contribution of genetic and environmental factors in the expression of enamel defects. AIM: This study examined prevalence and site concordance of EH and opacity in the primary dentition of 2- to 4-year-old twins and singleton controls to assess the relative contribution of genetics and the environment to the aetiology of these defects. DESIGN: The study sample consisted of 88 twin children and 40 singletons aged 2-4 years of age. Medical histories were obtained and the children examined for enamel defects. RESULTS: The prevalence of EH by teeth was 21% in monozygotic twins (MZ), 22% in dizygotic twins (DZ), and 15% in singleton controls. Twins showed a higher prevalence of EH compared with singletons (P < 0.05). Factors contributing to increase EH in twins were neonatal complications including intubation. There were no significant differences in site concordance of EH within the MZ twin pairs compared with DZ twin pairs when only presence of EH was considered, whereas a greater concordance was noted between MZ twin pairs compared with DZ twin pairs when both presence and absence of EH were considered. CONCLUSIONS: The results suggest that both genetic and environmental factors contribute to observed variation of EH, although it is likely that environmental factors exert a greater influence.

Comparison of enamel defects in the primary and permanent dentitions of children from a low-fluoride District in Australia.

PURPOSE: The purpose of this study was to compare developmental defects of enamel (DDE) in the primary and permanent dentitions of children from a low-fluoride district. METHODS: A total of 517 healthy schoolchildren were examined using the modified DDE criteria. RESULTS: The prevalence of DDE in the primary and permanent dentition was 25% and 58%, respectively (P<.001). The mean number of teeth with enamel opacity per subject was approximately threefold compared to that affected by enamel hypoplasia (3.1±3.8 vs 0.8±1.4, P<.001 in the primary dentition and 3.6±4.7 vs 1.2±2.2, P<.001 in the permanent dentition). Demarcated opacities (83%) were predominant compared to diffuse opacities (17%), while missing enamel was the most common type of enamel hypoplasia (50%), followed by grooves (31%) and enamel pits (19%) (P=.04). In the permanent dentition, diffuse and demarcated opacities were equally frequent, while enamel grooves were the commonest type of hypoplasia (52%), followed by missing enamel (35%) and enamel pits (5%; P<.001). CONCLUSIONS: In a low-fluoride community, developmental defects of enamel were twice as common in the permanent dentition vs the primary dentition. In the primary dentition, the predominant defects were demarcated opacities and missing enamel, while in the permanent dentition, the defects were more variable.