Fertility and immigration: Do immigrant mothers hand down their fertility pattern to the next generation? Evidence from Norway.

We examined whether the fertility pattern of immigrant mothers is handed down to the next generation. Our analyses were carried out on population register data. These data contained information on all immigrants to Norway from 123 countries during the period 1935-1995. We examined whether there was a relationship between the fertility rate in the country of origin and the number of children for generations 1.5 and 2 in Norway. We estimated three models: fixed effects for country of origin, fixed effects for region, and no fixed effects. The three specifications yielded estimates with overlapping confidence intervals. We interpret the estimates from the models with fixed effects for region, and the model with no fixed effects as upper-bound estimates. They show that an increase of 1.00 in the fertility rate in the country of origin leads to an average increase in the number of children of 0.12 (no fixed effects) or 0.14 (fixed effects for region) for immigrant women in generations 1.5 and 2. The estimate from the model with fixed effects for country of origin was small and not statistically significant at the conventional level. We interpret this as a lower-bound estimate. Our upper-bound estimates for generations 1.5 and 2 are smaller than the estimates for generation 1, i.e. there has been a decrease in the fertility rate from the first to the second generation. As a result, if the proportion of the population with an immigrant background continues to increase, it may increase at a slower rate in the future.

Does subsidized orthodontic treatment reduce inequalities in access? Evidence from Norway based on population register data.

OBJECTIVE: An important part of Norwegian welfare policy is to provide subsidized orthodontic treatment for children and adolescents. The objective of this policy is that dental services should be allocated according to children's need for treatment, and not according to parents' ability to pay. The probability of receiving orthodontic treatment independent of parent's household income was examined. METHODS: The study population encompassed children and adolescents aged 10-18 years in 2019 (n = 354 439). Information about whether they had started orthodontic treatment was obtained from the Norwegian Health Economics Administration. The key independent variable was net equalized household income. Inequalities were measured using concentration indices, which were estimated according to the severity of the malocclusion (very great need, great need, obvious need and no need). Two indices were used to measure relative inequality: the unstandardized concentration index and the partial concentration index. Absolute inequality was measured using the corrected concentration index. Relevant control variables were included in some of the analyses. RESULTS: The unstandardized indices were in the range 0.04 (very great need) to 0.05 (obvious need). For all three groups of severity, the 95% confidence intervals overlapped. The values of the partial indices were significantly lower than the values of the unstandardized indices. The partial indices were in the range 0.008 (very great need) to 0.03 (obvious need). The 95% confidence intervals for the partial indices did not overlap with the 95% confidence intervals of the unstandardized indices. For all three groups of severity, the indices that measured absolute inequality were close to zero. CONCLUSIONS: It is possible to achieve the egalitarian aim of equality in service provision by subsidizing orthodontic treatment. This is possible within a system where the cost of orthodontic treatment is reimbursed according to the criteria of need. These criteria function in such a way that patients with the greatest need for orthodontic treatment are given the highest priority.

Inter-pregnancy interval and placental weight. A population based follow-up study in Norway.

INTRODUCTION: We studied changes in placental weight from the first to the second delivery according to length of the inter-pregnancy interval. METHODS: We followed all women in Norway from their first to their second successive singleton pregnancy during the years 1999-2019, a total of 271 184 women. We used data from the Medical Birth Registry of Norway and studied changes in placental weight (in grams (g)) according to the length of the inter-pregnancy. Adjustments were made for year and maternal age at first delivery, changes in the prevalence of maternal diseases (hypertension and diabetes), and a new father to the second pregnancy. RESULTS: Mean placental weight increased from 655 g at the first delivery to 680 g at the second. The adjusted increase in placental weight was highest at inter-pregnancy intervals <6 months; 38.2 g (95 % CI 33.0g-43.4 g) versus 23.2 g (95 % CI 18.8g-27.7 g) at inter-pregnancy interval 6-17 months. At inter-pregnancy intervals ≥18 months, placental weight remained higher than at the first delivery, but was non-different from inter-pregnancy intervals 6-17 months. Also, after additional adjustment for daily smoking and body mass index in sub-samples, we found the highest increase in placental weight at the shortest inter-pregnancy interval. We estimated no difference in gestational age at delivery or placental to birthweight ratio according to inter-pregnancy interval. DISCUSSION: Placental weight increased from the first to the second pregnancy, and the increase was most pronounced at short inter-pregnancy intervals. The biological causes and implications of such findings remain to be studied.

A 30-year retrospective cohort outcome study of periodontal treatment of stages III and IV patients in a private practice.

AIM: Tooth loss studies show that periodontal treatment is effective. However, it is not known whether these results can be projected into a lifetime of treatment. The aim of the study was to study all patients with stages III/IV of periodontitis over 30 years in a private practice. MATERIALS AND METHODS: All patients referred between 1986 and 1990 were monitored for 30 years for tooth loss and prognostic factors. All dropouts were accounted for. RESULTS: In all, 386 patients were followed, of whom 283 patients dropped out, leaving 103 patients (67 females and 36 males, average age 40.1 years) monitored over 30 years. Tooth loss was stable until 16 years, when the population was divided into groups of low (n = 65), moderate (n = 18) and high (n = 20) tooth loss, losing 1.05 (SD 1.27), 4.83 (SD 0.96) and 11.90 (SD 4.25) teeth, respectively. The strongest prognostic factors were first-degree relatives with periodontitis, periodontal treatment before the age of 35 years, diabetes and patients with teeth with initial hopeless prognosis. CONCLUSION: The majority of patients with stages III and IV periodontitis could be successfully treated with conventional periodontal treatment over a period of 30 years. The findings suggest that retrospective studies with shorter observation times cannot automatically be projected onto the outcome of a lifetime of periodontal treatment.

Do Norwegian private dental practitioners with too few patients compensate for their loss of income by providing more services or by raising their fees?

OBJECTIVE: In Norway, supply of dental services exceeds demand, mainly because of the marked improvement in dental health during the last few decades. The aim of the study was to investigate whether private dental practitioners counteract a fall in demand for their services by providing more services or by raising their fees. METHODS: The data were collected using a questionnaire that was sent to all private dental practitioners in Norway. Altogether 1237 practitioners responded, which gave a response rate of 56%. Our sample was representative of the population of practitioners in Norway. As a measure of patient supply, responses from the following questions were used: 'Based on an overall assessment of economy, workload and other personal factors, is the number of regular patients adequate? If not, do you wish to have more patients, or fewer patients?' The outcome variables were dental fees, length of recall interval and mean cost per visit. The data were analysed using ordinary least square regression and a linear probability model. The following characteristics of the private dental practitioners were included as control variables: age, gender, work experience in years and whether they worked in a solo practice. To test the robustness of the findings, a supplementary analysis with the patient as the unit of analysis was carried out, using survey data of Norwegians aged 20 years and older. Based on this survey, the relationship between population: dentist ratio and mean cost per dental visit were examined. RESULTS: Nearly 40% of all practitioners reported that they had too few patients. They compensated for their loss of income by raising their fees, by recalling their patients more often and by increasing the cost per visit. The finding in the supplementary analysis using survey data from patients was similar to the findings in the main analyses using survey data from private dental practitioners. CONCLUSION: The findings show that practitioners have market power. They were able to counteract a fall in demand for their services by providing more services and by raising their fees. The dental profession should be encouraged to provide appropriate services, in the present situation where supply exceeds demand.

Patient-Reported Outcome Measures on Oral Hygiene, Periodontal Health, and Treatment Satisfaction of Orthodontic Retention Patients up to Ten Years after Treatment-A Cross-Sectional Study.

Background: This cross-sectional study evaluated patient-reported outcome measures (PROMs) on (1) oral hygiene, (2) periodontal health, (3) retainer failure, (4) orthodontic treatment satisfaction, and (5) outcome satisfaction in orthodontic retention patients. The purpose of the study was to evaluate whether orthodontic retention treatment is associated with patient-reported outcome measures on oral hygiene, periodontal health, and treatment satisfaction. Methods: A ten-item questionnaire on the five PROMs was conducted among 211 consecutive retention patients up to ten years following orthodontic treatment. Linear regression models were computed to detect possible associations between the PROMs and retention treatment or patient characteristics. Results: The presence of a fixed lingual retainer was not associated with the reduced ability to perform oral hygiene, self-perceived periodontal health, or orthodontic outcome satisfaction. Older patients were more content with the orthodontic treatment result (p < 0.05). Patients with fixed lingual retainers in the mandible were less satisfied with the course of orthodontic treatment (p < 0.05). Smokers more often reported gingival bleeding (p < 0.05). Females reported increased gingival recessions (p < 0.05) and perceived their teeth as longer than before treatment (p < 0.05). Longer orthodontic treatment duration corresponded to retainer failure (p < 0.05). Conclusions: In general, long-term orthodontic retention patients were satisfied with orthodontic treatment. These patients reported the satisfactory ability to perform adequate oral hygiene and periodontal health, and they communicated a high degree of treatment and outcome contentment. However, patients with a retainer in the mandible were less satisfied with orthodontic treatment.

The impact of the introduction of intrapartum fetal ECG ST segment analysis. A population study.

INTRODUCTION: ST segment analysis (STAN) of the fetal electrocardiogram was introduced as an adjunct to cardiotocography for intrapartum fetal monitoring 30 years ago. We examined the impact of the introduction of STAN on changes in the occurrence of fetal and neonatal deaths, Apgar scores of <7 at 5 min, intrapartum cesarean sections, and instrumental vaginal deliveries while controlling for time- and hospital-specific trends and maternal risk factors. MATERIAL AND METHODS: Data were retrieved from the Medical Birth Registry of Norway from 1985 to 2014. Individual data were linked to the Education Registry and the Central Person Registry. The study sample included 1 132 022 singleton births with a gestational age of 36 weeks or beyond. Information about the year of STAN introduction was collected from every birth unit in Norway using a questionnaire. Our data structure consisted of a hospital-year panel. We applied a linear probability model with hospital-fixed effects and with adjustment for potentially confounding factors. The prevalence of the outcomes before and after the introduction of STAN were compared within each birth unit. RESULTS: In total, 23 birth units, representing 76% of all births in Norway, had introduced the STAN technology. During the study period, stillbirths declined from 2.6 to 1.9 per 1000 births, neonatal deaths declined from 1.7 to 0.7 per 1000 live births, babies with Apgar score <7 at 5 min after birth increased from 7.4 to 9.5 per 1000 births, intrapartum cesarean sections increased from 6.4% to 9.5%, and instrumental vaginal deliveries increased from 7.8% to 10.9%. Our analyses found that the introduction of STAN was not associated with the decline in proportion of stillbirths (p =0.76) and neonatal deaths (p =0.76) or with the increase in intrapartum cesarean sections (p =0.92) and instrumental vaginal deliveries (p =0.78). However, it was associated with the increased occurrence of Apgar score <7 at 5 min (p =0.01). CONCLUSIONS: There is no evidence that the introduction of STAN contributed to changes in the rates of stillbirths, neonatal deaths, intrapartum cesarean sections, or instrumental vaginal deliveries. There was an association between the introduction of STAN and a small increase in neonates with low Apgar scores.

Does the use of Doppler ultrasound reduce fetal mortality? A population study of all deliveries in Norway 1990-2014.

BACKGROUND: The aim of the present study was to examine the effect that the introduction of Doppler ultrasound in obstetric care has had on fetal death in Norway. One mechanism by which Doppler ultrasound may reduce fetal death may be through the increased use of Caesarean delivery. Therefore, we also examined the effect that the use of Doppler ultrasound has had on the use of Caesarean delivery. METHODS: The Medical Birth Registry of Norway provided detailed medical information for ∼1.2 million deliveries from 1990 to 2014. Information about the year of introduction of Doppler ultrasound was collected directly from the maternity units, using a questionnaire. The data were analysed using a hospital fixed-effects regression model with fetal death as the outcome measure. The key independent variable was the introduction of Doppler ultrasound at each maternity ward. Hospital-specific trends and risk factors of the mother for fetal death were included as covariates. RESULTS: For pre-term deliveries, the introduction of Doppler ultrasound contributed to a reduction in fetal death of ∼30% and to an increase in planned Caesarean section of ∼15%. There were no effects for emergency Caesarean sections or inductions pre-term. The introduction of Doppler ultrasound had no effect on fetal death or Caesarean section for term deliveries. CONCLUSIONS: The introduction of Doppler ultrasound during the 1990s and 2000s made a significant contribution to the decline in the number of pre-term fetal deaths in Norway. Increased use of Caesarean section may have contributed to this reduction.

Inequality in access to dental services in a market-based dental care system: A population study from Norway 1975-2018.

OBJECTIVE: To examine income-related inequalities in access to dental services from 1975 to 2018. In Norway, dental care services for adults are privately financed. This may lead to income-related inequalities in access. In the early 1970s, that is, at the beginning of the study period, there were marked inequalities in access to dental services according to personal income. However, from the beginning of the 1970s, there has been a large increase in gross national income per capita in Norway as a result of the growth of the oil and gas industry. This increase in income also meant that people with a low income in 1975 had a rise in their level of income. According to the law of diminishing utility, an increase in income leads to higher consumption of dental services for people with a low level of income compared to people with a high level of income. The study hypothesis is that the inequalities in access to dental services that existed in 1975 became less over time. METHODS: Statistics Norway collected samples of cross-sectional health survey data for the following years: 1975, 1985, 1995, 2002, 2008, 2012 and 2018. For each sample, individuals 21 years and older were drawn randomly from the non-institutionalized adult population using a two-stage stratified cluster sample technique. Inequalities were measured using the concentration index. The dependent variable was the use of dental services during the last year, and the key independent variable was equivalized household income. RESULTS: The concentration index for inequalities in use of dental services according to income decreased from 0.10 (95% CI = 0.09, 0.11) in 1975 to 0.04 (95% CI = 0.03, 0.05) in 2018. The decrease was particularly large from 2002 to 2012. This was a period with a large growth in gross national income. CONCLUSION: People with a low income had a marked increase in their purchasing power from 1975 to 2018. This coincided with an increase in demand for dental care for this low-income group.

Proposing a model for auditing data quality of long-term periodontal outcome studies.

OBJECTIVE: The assessment of the success of conventional periodontal therapy is based on retrospective studies from private practice and university clinics. Due to their marked heterogeneity, it is difficult to assess the data quality and rate these studies. The aim is to test a model for auditing and rating the data quality of periodontal outcome studies. METHODS: The method was adapted from the NIH Health Care Systems Collaboratory model, which uses three data quality dimensions: completeness (including all the relevant variables), consistency (ensuring that the same variables are compared) and accuracy (proportion of data in error with a gold standard). The model was applied to studies from a Norwegian specialist practice and data from the Norwegian Health database to test if the auditing process was workable using real world data. RESULTS: Forty-seven risk and prognostic factors were included for completeness. Seven variables were specified for consistency: tooth loss, smoking, systemic conditions, oral hygiene, individual tooth prognosis, maintenance profiles and timing of extractions. The factors tested showed a 95.7% completeness and an average accuracy deviation from the gold standard of -2.3% for each of the risk/prognostic factors and an overall study score of 93.3%. CONCLUSIONS: It was possible to develop a method for auditing and rating the quality of periodontal outcome studies. The model was tested using both real world data including risk and prognostic factors from individual outcome studies and national big data. The application of the model to these sets of data showed a high accuracy of the risk/prognostic factors and a close relationship with national big data.

Improvements in Dental Health and Dentists' Workload in Norway, 1992 to 2015.

OBJECTIVES: There has been a marked improvement in dental health in Norway during the last few decades. What effect has this had on provision of dental services, and how has private dental practitioners' assessment of their workload changed? METHODS: The data were from 2 large surveys of private dental practitioners carried out in 1992 (n = 1056) and 2015 (n = 1237). An analysis of nonresponders showed that they were evenly distributed according to their age, gender, and the region in which their practice was located. Thus, the samples were representative of private dental practitioners. For 1 representative week in practice, the practitioners were asked to report the number of visits and the number of patients who received 1 or more of the following items of treatment: filling, crown, bridge, denture, root filling, extraction, and periodontal treatment. As a measure of patient supply, the responses from the following questions were used: "Based on an overall assessment of economy, workload, and other personal factors, is the number of regular patients adequate? If not, do you wish to have more patients or fewer patients?" RESULTS: From 1992 to 2015, the annual number of visits per practitioner decreased by 23%. The number of patients per practitioner who received fillings, crowns, bridges, dentures, root fillings, or extractions decreased by 50% or more. The decrease was largest for practitioners younger than 35 years and for men. The proportion of practitioners who reported a deficit of patients increased from 20% to 37%. CONCLUSIONS: Many dentists will have too few patients and a fall in income in the years to come is expected.

The impact of primary care physician density on perinatal health: Evidence from a natural experiment.

We examined the impact of primary care physician density on perinatal health outcomes in Norway. From 1992 and onwards, primary care physicians who chose to work in selected remote municipalities were given an annual reduction in their student loan. This reduction, combined with increased supply of physicians, led to an increase in the density of primary care physicians in these selected municipalities. Our register-based population study showed that this increase in physician density significantly improved perinatal health in terms of fewer fetal deaths and increased birth weight. The richness of the data allowed us to perform several robustness tests.

Periodontal status in long-term orthodontic retention patients up to 10 years after treatment - a cross-sectional study.

OBJECTIVE: To assess periodontal status in long-term orthodontic retention patients and investigate possible risk indicators. MATERIALS AND METHODS: Plaque index (PI), gingival index (GI), probing pocket depth (PPD), gingival recessions (GR) and calculus were recorded in 211 patients with or without fixed retainers. RESULTS: Periodontal parameters were within the limits of clinically healthy periodontium. The use of fixed retainers was associated with higher PI in the maxilla (ß = 1.10 [0.37]; p <.05). Older age was associated with higher PI in the mandible (ß = 0.27 [0.11]; p <.05). Smoking was associated with gingival bleeding on both palatal (ß = 0.63 [0.16]; p < .01) and labial sides in the maxilla (ß = 0.46 [0.20]; p <.05). Smoking was also associated with increased prevalence of GR in the mandible (ß = 0.24 [0.07]; p <.01), while use of snuff had similar effect on the labial side in the maxilla (ß = 0.35 [0.08]; p <.01). Higher age (ß = 0.05 [0.02]; p <.05) and the presence of a retainer (ß = 0.23 [0.07]; p < .05) were associated with calculus accumulation on the lingual side in the mandible. CONCLUSION: The present observational study suggest that long-term fixed retainers alone have no detrimental effect on the periodontium. Additional factors may increase the risk of plaque deposits and increased probing pocket depths. Further prosepective studies are needed to confirm the present outcome.

Educational inequalities in access to fixed prosthodontic treatment in Norway. Causal effects using the introduction of a school reform as an instrumental variable.

OBJECTIVES: Equality in access to dental services, independent of level of education, is an important aim of Scandinavian welfare policy. In Norway, this policy is the main justification for a dental public subsidy scheme for adults. An important part of the subsidy scheme is to cover the cost of fixed prosthodontic treatment, including implant-based crowns and bridges for premolars, canines and incisors. A stated policy goal is to secure equal access to everybody in need of these services, independent of their level of education. The aim of this study was to estimate the causal effect of education on the probability of receiving fixed prosthodontic treatment in the adult Norwegian population. METHODS: During the period 1960-1972, all municipalities in Norway were required to increase the number of compulsory years of education from seven to nine years. We used this education reform as the instrumental variable to create exogenous variation in the individual's number of years of education. The education data were combined with data from the Norwegian Health Economics Administration, which contained our outcome variable. Our sample included individuals with 9 years education or less. Altogether 113 237 individuals were included in the study. RESULTS: For men, the first stage regression coefficient was 0.87 (confidence interval: 0.82-0.92). This means that the reform resulted in 0.87 additional years of education. For men, the probability of receiving fixed prosthodontic treatment increased by 0.67 percentage points per additional year of schooling. For women, the first stage regression coefficient was 0.84 (confidence interval: 0.79-0.88). The second stage regression coefficient was small (= 0.0022) and not statistically significant at a conventional level. CONCLUSION: From a welfare policy point of view, for men, the subsidy scheme has not succeeded to redistribute resources so that dental services are accessible independent of their social status.

Provision of treatment for periodontitis in Norway in 2013 - a national profile.

BACKGROUND: Epidemiological studies have reported high levels of periodontal diseases worldwide. Over the last 40 years, Norway has introduced several measures including major financial support to reduce periodontal diseases. The aims of this study were to establish the present level of periodontal treatment, the treatment profiles for the nation, and to assess if long-term clinical data support the findings. MATERIALS AND METHODS: The database of the Norwegian Health Economic Administration for 2013 was analysed to establish the prevalence of treated periodontitis in a cross-sectional register-based study. Treatment profiles including patients' ages, gender, geographic distributions, treatment types, prosthetic tooth replacements and the treatment distributions between the dental health professionals were assessed. RESULTS: 4.4% of the 20 years and older age group was treated for periodontitis. More females (55%) than males (45%) were treated with predominance in the 60-69 year age group. Private general dental practitioners performed 43.8% of the total periodontal treatment, while dental hygienists performed 22.5%. Periodontists performed 32.8% of the non-surgical and 74.6% of the surgical treatment. Tooth replacements for teeth lost due to periodontal diseases were provided for 0.57% of the population. Clinical studies from Norway showed marked improvements in the periodontal parameters examined over the last 40 years. CONCLUSION: The frequency of periodontal treatments in Norway was low, but sufficient to maintain major tooth retention for the population. Long-term external clinical data supported these findings. The treatments were well distributed between private general dental practitioners, hygienists and periodontists.

Who dies early? Education, mortality and causes of death in Norway.

We estimated the effects of education on mortality and causes of death in Norway. We identified causal effects by exploiting the staggered implementation of a school reform that increased the length of compulsory education from seven to nine years. The municipality-level education data were combined with complete records of all deaths from 1960 to 2015 from the Norwegian Cause of Death Registry. These data covered the entire life span of persons aged 16-64. One additional year of education caused a reduction in mortality of about 10% for men. The effect was negligible for women. For men, a large part of the effect was due to fewer accidental deaths. We suggest two explanations for this finding. First, there are differences in risk-taking behaviour between people with a high level of education and those with a low level. Second, more education leads to upward occupational mobility. This mobility is mainly from occupations for which the risk of accidents is high to occupations for which the risk is low. Our results supported the fundamental cause theory. This is because education had a stronger effect on mortality for causes of death that are preventable than for causes of death that are not preventable. More education had no effect on the probability of dying of diseases that were amenable to medical intervention only. This gives some support to our results that patients are treated equally, independent of their level of education. This may be due to the large public involvement in financing and provision of health services.