Oral Health Birth Cohort Studies: Achievements, Challenges, and Potential

Birth cohorts are those among observational studies that provide understanding of the natural history and causality of diseases since early in life. Discussions during an International Association for Dental Research symposium in London, United Kingdom, in 2018, followed by a workshop in Bangkok, Thailand, in 2019, concluded that there are few birth cohort studies that consider oral health and that a broader discussion on similarities and differences among those studies would be valuable. This article aims to 1) bring together available long-term data of oral health birth cohort studies from the low, middle, and high-income countries worldwide and 2) describe similarities and differences among these studies. This work comprises 15 studies from all 5 continents. The most studied dental conditions and exposures are identified; findings are summarized; and methodological differences and similarities among studies are presented. Methodological strengths and weaknesses are also highlighted. Findings are summarized in 1) the negative impact of detrimental socioeconomic status on oral health changes over time, 2) the role of unfavorable patterns of dental visiting on oral health, 3) associations between general and oral health, 4) nutritional and dietary effects on oral health, and 5) intergenerational influences on oral health. Dental caries and dental visiting patterns have been recorded in all studies. Sources of fluoride exposure have been documented in most of the more recent studies. Despite some methodological differences in the way that the exposures and outcomes were measured, some findings are consistent. Predictive models have been used with caries risk tools, periodontitis occurrence, and permanent dentition orthodontic treatment need. The next steps of the group's work are as follows: 1) establishing a consortium of oral health birth cohort studies, 2) conducting a scoping review, 3) exploring opportunities for pooled data analyses to answer pressing research questions, and 4) promoting and enabling the development of the next generation of oral health researchers.

Evidence-based dentistry skill acquisition by second-year dental students

INTRODUCTION

Identification and assessment of Evidence-based dentistry (EBD) outcomes have been elusive. Our objective was to describe EBD skill acquisition during the second (D2) year of pre-doctoral dental education and student competency at the end of the year.

METHODS

The first and fourth (final) curricular-required EBD Exercises (ie, application of the first 4 steps of the 5-Step evidence-based practice process applied to a real or hypothetical situation) completed by D2 students (n = 151) during 2014-2015 and 2015-2016 were evaluated to measure skill acquisition through use of a novel rubric with measures of performance from novice to expert. Exercises were evaluated on the performance for each step, identification of manuscript details and reflective commentary on manuscript components. Changes in performance were evaluated using the chi-square test for trend and the Wilcoxon signed-rank test.

RESULTS

Seventy-eight per cent of students scored competent or higher on the Ask step at the beginning of the D2 year; scores improved with 58% scoring proficient or expert on the fourth Exercise (P < .001). Most students were advanced beginners or higher in the Acquire, Appraise and Apply steps at the beginning of the D2 year, with minimal growth observed during the year. Identification of manuscript details improved between the first and fourth Exercises (P = .015); however, depth of commentary skills did not change.

DISCUSSION

Unlike previous investigations evaluating EBD knowledge or behaviour in a testing situation, we evaluated skill acquisition using applied Exercises.

CONCLUSION

Consistent with their clinical and scientific maturity, D2 students minimally performed as advanced beginners at the end of their D2 year.

Evidence of Early Emergence of the Primary Dentition in a Northern Plains American Indian Population

The purposes of this study were to describe primary tooth emergence in an American Indian (AI) population during the first 36 mo of life to compare 1) patterns of emergence between male and female children and 2) tooth emergence between these AI children and other U.S. ethnic groups. Data were derived from a birth cohort of 239 AI children from a Northern Plains tribe participating in a longitudinal study of early childhood caries, with examination data at target ages of 8, 12, 16, 22, 28, and 36 mo of age (±1 mo). Patterns of emergence in AI children were characterized and sex comparisons accomplished with interval-censored survival methodology. Numbers of erupted teeth in AI children at each age were compared via Kruskal-Wallis tests against those in children of the same age, as drawn from a cross-sectional study of dental caries patterns in Arizona; these comparisons were based on the dental examinations of 547 White non-Hispanic and 677 Hispanic children. Characterization of time to achievement of various milestones-including emergence of the anterior teeth, the first molars, and the complete primary dentition-provided no evidence of sex differences among AI children. AI children had significantly more teeth present at 8 mo (median, 3) than either White non-Hispanic (P < 0.0063) or Hispanic (P < 0.0001) children (median, 2 each). This was also true at 12 mo (P < 0.001; medians, 8 vs. 6 and 7, respectively) and 16 mo (P < 0.001; medians, 12 vs. 11 each). Less pronounced differences were seen at 22 mo (P < 0.0001). White non-Hispanic and Hispanic children did not differ at any time considered (P > 0.05). These results provide evidence of earlier tooth emergence in AI children than in the other 2 ethnicities. Although the underlying etiology of the severity of early childhood caries in AI children is likely to be multifactorial, earlier tooth emergence may be a contributing factor. Knowledge Transfer Statement: The findings of this study have practical implications for practitioners providing childhood oral health care to ethnic groups with early tooth emergence. It may be important to provide parents with information on toothbrushing, dentist visits, and other practices supportive of good oral health as early as possible to protect their children's primary dentition.

An approach on defining competency in evidence-based dentistry

INTRODUCTION

Assessment of evidence-based dentistry (EBD) knowledge and behaviour is hampered by lack of explicit competency criteria. This void impedes instructional design and assessment of student growth during the educational process.

METHODS

Knowledge and cognitive domains supporting educational objectives in a pre-doctoral dental programme were identified for each level of the EBD five-step process. We articulated educational objectives with behavioural expectations for each level of skill acquisition at each step of the EBD process. Outcome evaluation criteria identify students' progressive level of skill acquisition from novice to expert.

RESULTS

The educational objectives, type of knowledge, and nature of the cognitive process supporting these objectives are presented for each step of the EBD process. For example, educational objectives of the "Ask" step include (i) to construct a question from the patient presentation and knowledge limitations that addresses the clinical problem and (ii) to articulate the Problem, Intervention/Exposure, Comparison, Outcome (PICO) components. Achievement of these objectives requires both factual information regarding the PICO format and the cognitive process of understanding. Educational outcome criteria consistent with a competent clinician include clear articulation of the PICO with identifiable pieces that relate to the clinical situation.

DISCUSSION

Assessment strategies for progression towards EBD competency are limited due to the complexity associated with evaluating EBD knowledge and behaviours. To evaluate performance, the EBD academic community must define competency expectations for entry into unsupervised general dental practice.

CONCLUSION

This framework offers measurable outcome evaluation criteria to initiate a conversation with academic peers regarding current gaps in EBD assessment.

Examining caries aetiology in adolescence with structural equation modelling

OBJECTIVES

This analysis examines the aetiology of caries development in adolescents using structural equation modelling to identify behavioural mediators of the relationship between socioeconomic status (SES) and caries incidence, and to investigate the role of sex on caries-preventive behaviour and caries.

METHODS

This analysis was based on data from the Iowa Fluoride Study, a longitudinal study of a birth cohort. We hypothesized that socioeconomic status earlier in life has a direct effect on caries development and an indirect effect from improved behavioural variables-dental visit attendance, toothbrushing frequency and percentage of beverage intake consisting of sugar-sweetened beverages-and that sex also plays a role in behavioural variables, as well as caries. A structural equation model was developed based on these hypotheses, and direct and indirect standardized path coefficients were calculated, as well as their standard errors.

RESULTS

Based on our proposed model, SES at birth significantly influences SES during adolescence, but not adolescent behaviours. The effect of SES during adolescence on caries in the permanent dentition is mediated by adolescent behaviours. Female participants have worse caries than male participants, despite lower self-reported percentages of sugar-sweetened beverage intake and more frequent brushing and dental attendance.

CONCLUSIONS

This analysis models the relationships among known causal factors for caries and suggests that the role of SES in caries may not be as important as previously thought and different behaviours that affect oral health between males and females as well as differences in caries between the sexes could begin during adolescence. These findings could help improve caries prevention programmes for adolescents.

Evidence-based dentistry: assessment to document progression to proficiency

INTRODUCTION

The integration of evidence-based dentistry (EBD) into pre-doctoral dental curricula requires the identification of desired outcomes, development of curricular content and design of assessment strategies which guide student performance whilst documenting achievement of desired curricular outcomes. Models for developing EBD curriculums have been described in the literature; however, the logistics of designing assessment instruments to progressively document student performance have received less attention. The objective of this article is to describe the University of Iowa's College of Dentistry's development and implementation of assessment strategies to guide student learning of EBD knowledge, application and assimilation to serve as a model for other institutions developing EBD assessment protocols.

ASSESSMENT DEVELOPMENT

Desired EBD knowledge and behaviour outcomes guided the development of curricular content and progressive formative and summative assessment strategies. Vertically and horizontally integrated educational activities enabling students to demonstrate EBD knowledge whilst modelling desired behaviours were identified, whilst assessment principles guided development of learning guides and assessment instruments to document achievement of desired outcomes. Consistent EBD language and educational activities are utilised throughout the 4-year interdisciplinary curriculum with stepwise assessment protocols matched to the curriculum. Examples of student learning guides and assessment instruments are provided.

SUMMARY

Curricular design guides development of assessment strategies. Assessment protocols provide consistent formative and summative feedback to enable continuous student growth to become proficient EBD practitioners.

Controls on the Fate and Speciation of Np(V) During Iron (Oxyhydr)oxide Crystallization

The speciation and fate of neptunium as Np(V)O2(+) during the crystallization of ferrihydrite to hematite and goethite was explored in a range of systems. Adsorption of NpO2(+) to iron(III) (oxyhydr)oxide phases was reversible and, for ferrihydrite, occurred through the formation of mononuclear bidentate surface complexes. By contrast, chemical extractions and X-ray absorption spectroscopy (XAS) analyses showed the incorporation of Np(V) into the structure of hematite during its crystallization from ferrihydrite (pH 10.5). This occurred through direct replacement of octahedrally coordinated Fe(III) by Np(V) in neptunate-like coordination. Subsequent analyses on mixed goethite and hematite crystallization products (pH 9.5 and 11) showed that Np(V) was incorporated during crystallization. Conversely, there was limited evidence for Np(V) incorporation during goethite crystallization at the extreme pH of 13.3. This is likely due to the formation of a Np(V) hydroxide precipitate preventing incorporation into the goethite particles. Overall these data highlight the complex behavior of Np(V) during the crystallization of iron(III) (oxyhydr)oxides, and demonstrate clear evidence for neptunium incorporation into environmentally important mineral phases. This extends our knowledge of the range of geochemical conditions under which there is potential for long-term immobilization of radiotoxic Np in natural and engineered environments.

Incorporation and retention of 99-Tc(IV) in magnetite under high pH conditions

Technetium incorporation into magnetite and its behavior during subsequent oxidation has been investigated at high pH to determine the technetium retention mechanism(s) on formation and oxidative perturbation of magnetite in systems relevant to radioactive waste disposal. Ferrihydrite was exposed to Tc(VII)(aq) containing cement leachates (pH 10.5-13.1), and crystallization of magnetite was induced via addition of Fe(II)aq. A combination of X-ray diffraction (XRD), chemical extraction, and X-ray absorption spectroscopy (XAS) techniques provided direct evidence that Tc(VII) was reduced and incorporated into the magnetite structure. Subsequent air oxidation of the magnetite particles for up to 152 days resulted in only limited remobilization of the incorporated Tc(IV). Analysis of both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data indicated that the Tc(IV) was predominantly incorporated into the magnetite octahedral site in all systems studied. On reoxidation in air, the incorporated Tc(IV) was recalcitrant to oxidative dissolution with less than 40% remobilization to solution despite significant oxidation of the magnetite to maghemite/goethite: All solid associated Tc remained as Tc(IV). The results of this study provide the first direct evidence for significant Tc(IV) incorporation into the magnetite structure and confirm that magnetite incorporated Tc(IV) is recalcitrant to oxidative dissolution. Immobilization of Tc(VII) by reduction and incorporation into magnetite at high pH and with significant stability upon reoxidation has clear and important implications for limiting technetium migration under conditions where magnetite is formed including in geological disposal of radioactive wastes.

Inadequate nutrient intakes are common and are associated with low diet variety in rural, community-dwelling elderly

Poor dietary habits and inadequate nutrient intakes are of concern in the elderly. The nutritional characteristics of those who survive to become the oldest are not well defined. Our goal was to describe dietary habits, nutrient intakes and nutritional risk of community-dwelling, rural Iowans, 79 y of age and older. Subjects were interviewed (n = 420) using a standardized format on one occasion in their homes and instructed to complete 3-d diet records (n = 261) after the in-home interview. Standardized interviews assessed demographic information, cognitive function and dietary habits (Nutrition Screening Initiative Checklist). Adequate nutrient intake was defined as consumption of the nutrient's estimated average requirement, 67% adequate intake or 67% recommended dietary allowance. Mean age was 85.2 y, 57% lived alone and 58% were widowed. Subjects completing 3-d diet records were younger, more cognitively intact and less likely to be at nutritional risk than subjects not completing diet records. The percentage of subjects with inadequate intakes of selected nutrients was 75% for folate, 83% for vitamin D and 63% for calcium. Eighty percent of subjects reported inadequate intakes of four or more nutrients. Diet variety was positively associated with the number of nutrients consumed at adequate intakes (r = 0.498), total energy (r = 0.522) and dietary fiber (r = 0.421). Our results suggest that rural, community-dwelling old have inadequate intakes of several nutrients. Recommendations to increase diet variety and consume a nutrient supplement may be necessary for elderly people to achieve adequate nutrient intakes.

In vitro and in vivo assessment of lipid peroxidation of infant nutrient preparations: effect of nutrition on oxygen toxicity

Commercial infant formulas, human milk, and lipid emulsions were analyzed for evidence of naturally occurring lipid peroxidation and for susceptibility to an in vitro oxidative challenge using neonatal rat lung, liver, or intestine homogenates. Peroxidation was assessed by quantitation of TBA reactants, diene conjugates, lipid peroxides, and ethane and pentane hydrocarbons. The peroxidation of commercial formulas and human milk was influenced by the nutrient composition, as PUFA and iron enhanced while vitamin E inhibited one or more of the peroxidation pathways. Formulas and lipid emulsions differed in their response to a biological oxidant challenge. Neither neonatal rat lung nor liver tissue were effective in peroxidizing the formula or human milk in vitro, but both formula and human milk were peroxidized by exposure to neonatal rat intestinal tissue. The lipid emulsion was readily peroxidized by neonatal rat lung, liver, and intestinal tissue. The influence of nutrition on survival in hyperoxia was also studied by exposing newborn rat pups to either air or greater than 95% oxygen in the course of feeding Ringer's lactate, Similac 24 + iron, human milk, or Intralipid 10%. The survival of newborn rat pups exposed to air or greater than 95% oxygen was affected by the type of diet received.

Human immunodeficiency virus: seroprevalence in parturients in rural South Carolina

To establish the prevalence of human immunodeficiency virus (HIV) in the population of childbearing women in a rural South Carolina community, a blinded seroprevalence survey was conducted using all cord blood samples collected during a one-year period at a signal hospital. There were 1,811 live births (57% white, 43% black) during that period. Of the 1,365 samples collected and tested, six (0.44%) were HIV-positive by enzyme-linked immunosorbent assay, and three (0.22%) were confirmed by Western blot analysis. Based on these percentages, we estimate that there are approximately 80 HIV-infected women of childbearing age among the 180,000 residents of our health district. Although the seroprevalence of HIV in our parturients is low, it is somewhat higher than that reported from other rural areas. We therefore recommend counseling and voluntary blood testing for HIV antibodies, with informed consent, for all pregnant women living within our health district.

Physiologic changes associated with endotracheal intubation in preterm infants

Physiologic changes associated with endotracheal intubation were examined in 10 preterm infants. Laryngoscopy was associated with apnea and minor abnormalities in cardiac rhythm in 2 infants. Three infants had nasal airflow recordings which demonstrated obstructed breaths during laryngoscopy. Systolic blood pressure (BP) increased 47% when the trachea was intubated, whereas heart rate and transcutaneous oxygen tension (PtcO2) decreased. Because endotracheal intubation is a physiologically stressful procedure, personnel who intubate preterm infants must be skilled and experienced to minimize the duration of laryngoscopy and the number of intubation attempts.

Physiologic changes associated with ligation of the ductus arteriosus in preterm infants

Cardiorespiratory and transcutaneous oxygen monitors were used on 13 preterm neonates to examine physiologic changes during ductus arteriosus ligation. Transcutaneous oxygen decreased 30 seconds after left lung deflation; all infants required increases in inspired oxygen and ventilation to correct abnormal values after the left lung was compressed. Transcutaneous oxygen decreased 30 seconds after ductus arteriosus ligation (mean delta tcPO2 = -17 mm Hg +/- 11.4) but increased 150 seconds after left lung inflation (mean delta tcPO2 = 46.9 mm Hg +/- 28.8). Arterial blood pressure increased (mean delta systolic BP = 17.9 mm Hg +/- 9.5) and heart rate decreased 10 seconds after ductus arteriosus ligation. In five neonates, gradual closure of the ductus arteriosus over 40 to 75 seconds resulted in a more gradual increase in blood pressure. Intraventricular hemorrhage was confirmed in two patients after surgery. Ligation of the ductus arteriosus results in an abrupt increase in blood pressure, which may be related to the pathogenesis of intraventricular hemorrhage. We suggest that the ductus arteriosus be closed gradually to allow a more gradual increase in blood pressure.

Transcutaneous oxygen monitoring of neonates during surgery

Thirteen neonates who underwent surgery under general anesthesia were studied for a cumulative total of 30 hr of intraoperative transcutaneous oxygen (tcO2) monitoring. Simultaneous umbilical or radial arterial blood gas measurements were recorded frequently throughout each operation. A variety of drugs and anesthetics (including halothane) were used during surgery. PaO2 ranged from 27 to 390 mm Hg and PaCO2 ranged from 11 to 75 mm Hg. All patients but one required adjustment of inspired oxygen to correct abnormal values. In 11 of 13 patients there was close correspondence between PaO2 and PtcO2 (r = .92) in the absence of hypotension. In one patient, the transcutaneous electrode came loose, in another patient with edema the tcO2 monitor was unreliable both during and after surgery (r = .25). A low PtcO2/PaO2 ratio (.48) in one patient suggested decreased blood volume, and the ratio returned to normal (1.0) after a blood transfusion. The tcO2 monitor was the earliest indicator of airway compromise (extubation and kinked endotracheal tube) in two patients. The tcO2 monitor was reliable with inspired halothane of 1% or less. Since intraoperative blood gases fluctuate greatly and because of the risks of hypoxia and retrolental fibroplasia, it is important that frequent blood gas monitoring be routinely performed during neonatal surgery. In the non-edematous, normotensive patient, the tcO2 monitor is reliable and can provide an early indicator of intraoperative airway compromise, hypovolemia, hypoxemia, or hyperoxemia.