Urban green spaces and behavioral and cognitive development in children: A health impact assessment of the Barcelona "Eixos Verds" Plan (Green Axis Plan)

BACKGROUND

Urban environments lack natural features, while nature exposure in cities has been associated with health benefits, including children's neurodevelopment. Through extensive street greening, Barcelona's Eixos Verds (Green Axis) Plan enhances safety, environment, and climate resilience. We aimed to assess the Eixos Verds Plan's potential impact on children's behavioral and cognitive development due to the increased green space expected under the Eixos Verds implementation.

METHODS

We performed a quantitative health impact assessment for Barcelona children at census-tract level (n = 1068). We assessed the Eixos Verds Plan's impact by comparing baseline green space distribution with the proposed plan, translating it into percentage green area (%GA) and Normalized Difference Vegetation Index (NDVI). By combining these exposure metrics with child-specific risk estimates and population data, we estimated potential improvements in children's behavioral and cognitive development due to full Eixos Verds implementation.

RESULTS

With the full Eixos Verds implementation, citywide, %GA increased by 6.9% (IQR: 6.4%; range: 0-23.1%) and NDVI by 0.065 (IQR: 0.083; range: 0.000-0.194). Child behavioral and cognitive development outcomes are expected to improve compared to the baseline. Based on NDVI increases, children's Total Difficulties and Hyperactivity/Inattention scores, based on the Strengths and Difficulties Questionnaire (SDQ), are projected to decrease by 5% (95% CI: 0-15%) and 6% (95% CI: 0-17%). Working Memory and Superior Working Memory scores are expected to increase by 4% and 5%, respectively, based on the computerized n-back test, while the Inattentiveness score could be reduced by 1%, based on the computerized attentional test (ANT).

INTERPRETATION

Urban greening as planning tool can improve behavioral and cognitive development in city children. Methods and results of our study are applicable to many cities worldwide, and similar results for children of real-life urban greening interventions can be expected.

The Superblock model: A review of an innovative urban model for sustainability, liveability, health and well-being

INTRODUCTION

Current urban and transport planning practices have significant negative health, environmental, social and economic impacts in most cities. New urban development models and policies are needed to reduce these negative impacts. The Superblock model is one such innovative urban model that can significantly reduce these negative impacts through reshaping public spaces into more diverse uses such as increase in green space, infrastructure supporting social contacts and physical activity, and through prioritization of active mobility and public transport, thereby reducing air pollution, noise and urban heat island effects. This paper reviews key aspects of the Superblock model, its implementation and initial evaluations in Barcelona and the potential international uptake of the model in Europe and globally, focusing on environmental, climate, lifestyle, liveability and health aspects.

METHODS

We used a narrative meta-review approach and PubMed and Google scholar databases were searched using specific terms.

RESULTS

The implementation of the Super block model in Barcelona is slow, but with initial improvement in, for example, environmental, lifestyle, liveability and health indicators, although not so consistently. When applied on a large scale, the implementation of the Superblock model is not only likely to result in better environmental conditions, health and wellbeing, but can also contribute to the fight against the climate crisis. There is a need for further expansion of the program and further evaluation of its impacts and answers to related concerns, such as environmental equity and gentrification, traffic and related environmental exposure displacement. The implementation of the Superblock model gained a growing international reputation and variations of it are being planned or implemented in cities worldwide. Initial modelling exercises showed that it could be implemented in large parts of many cities.

CONCLUSION

The Superblock model is an innovative urban model that addresses environmental, climate, liveability and health concerns in cities. Adapted versions of the Barcelona Superblock model are being implemented in cities around Europe and further implementation, monitoring and evaluation are encouraged. The Superblock model can be considered an important public health intervention that will reduce mortality and morbidity and generate cost savings for health and other sectors.

Environmental health impacts and inequalities in green space and air pollution in six medium-sized European cities

BACKGROUND

The GoGreenRoutes project aims to introduce co-created nature-based solutions (NBS) to enhance environmental quality in six medium-sized cities (Burgas, Lahti, Limerick, Tallinn, Umeå, and Versailles). We estimated the mortality and economic impacts attributed to suboptimal exposure to green space and air pollution, economic impacts, and the distribution thereof the adult population by socioeconomic status.

METHODS

We retrieved data from publicly accessible databases on green space (NDVI and % Green Area), air pollution (NO2 and PM2.5) and population (≥20 years, n = 804,975) at a 250m × 250m grid-cell level, and mortality for each city for 2015. We compared baseline exposures at the grid-cell to World Health Organization's recommendations and guidelines. We applied a comparative risk assessment to estimate the mortality burden attributable to not achieving the recommendations and guidelines. We estimated attributable mortality distributions and the association with income levels.

RESULTS

We found high variability in air pollution and green spaces levels. Around 60% of the population lacked green space and 90% were exposed to harmful air pollution. Overall, we estimated age-standardized mortality rates varying from 10 (Umeå) to 92 (Burgas) deaths per 100,000 persons attributable to low NDVI levels; 3 (Lahti) to 38 (Burgas) per 100,000 persons to lack of % Green Area; 1 (Umeå) to 88 (Tallinn) per 100,000 persons to exceedances of NO2 guidelines; and 1 (Umeå) to 206 (Burgas) per 100,000 persons to exceedances of PM2.5 guidelines. Lower income associated with higher or lower mortality impacts depending on whether deprived populations lived in the densely constructed, highly-trafficked city centre or greener, less polluted outskirts.

CONCLUSIONS

We attributed a considerable mortality burden to lack of green spaces and higher air pollution, which was unevenly distributed across different social groups. NBS and health-promoting initiatives should consider socioeconomic aspects to regenerate urban areas while providing equally good environments.

Spatial and sector-specific contributions of emissions to ambient air pollution and mortality in European cities: a health impact assessment

BACKGROUND

Ambient air pollution is a major risk to health and wellbeing in European cities. We aimed to estimate spatial and sector-specific contributions of emissions to ambient air pollution and evaluate the effects of source-specific reductions in pollutants on mortality in European cities to support targeted source-specific actions to address air pollution and promote population health.

METHODS

We conducted a health impact assessment of data from 2015 for 857 European cities to estimate source contributions to annual PM_2·5 and NO₂ concentrations using the Screening for High Emission Reduction Potentials for Air quality tool. We evaluated contributions from transport, industry, energy, residential, agriculture, shipping, and aviation, other, natural, and external sources. For each city and sector, three spatial levels were considered: contributions from the same city, the rest of the country, and transboundary. Mortality effects were estimated for adult populations (ie, ≥20 years) following standard comparative risk assessment methods to calculate the annual mortality preventable on spatial and sector-specific reductions in PM_2·5 and NO₂.

FINDINGS

We observed strong variability in spatial and sectoral contributions among European cities. For PM_2·5, the main contributors to mortality were the residential (mean contribution of 22·7% [SD 10·2]) and agricultural (18·0% [7·7]) sectors, followed by industry (13·8% [6·0]), transport (13·5% [5·8]), energy (10·0% [6·4]), and shipping (5·5% [5·7]). For NO₂, the main contributor to mortality was transport (48·5% [SD 15·2]), with additional contributions from industry (15·0% [10·8]), energy (14·7% [12·9]), residential (10·3% [5·0]), and shipping (9·7% [12·7]). The mean city contribution to its own air pollution mortality was 13·5% (SD 9·9) for PM_2·5 and 34·4% (19·6) for NO₂, and contribution increased among cities of largest area (22·3% [12·2] for PM_2·5 and 52·2% [19·4] for NO₂) and among European capitals (29·9% [12·5] for PM_2·5 and 62·7% [14·7] for NO₂).

INTERPRETATION

We estimated source-specific air pollution health effects at the city level. Our results show strong variability, emphasising the need for local policies and coordinated actions that consider city-level specificities in source contributions.

FUNDING

Spanish Ministry of Science and Innovation, State Research Agency, Generalitat de Catalunya, Centro de Investigación Biomédica en red Epidemiología y Salud Pública, and Urban Burden of Disease Estimation for Policy Making 2023-2026 Horizon Europe project.

An urban green space intervention with benefits for mental health: A health impact assessment of the Barcelona "Eixos Verds" Plan

BACKGROUND

Mental health disorders account for over 30% of the global burden of disease. There is a positive association between green space exposure and better mental health, and therefore urban greening can be an effective public health tool. Barcelona is a compact city with one of the highest population and traffic densities in Europe, with limited green spaces. Under the umbrella of the Superblock model, the Barcelona City council is implementing the Eixos Verds Plan for extensive street greening. We estimated the potential mental health benefits of this plan.

METHODS

We performed a quantitative health impact assessment at the Barcelona grid-cell level (n = 1,096). We compared the baseline green space situation (2015) with the proposed plan and translated the increase in green space into a) percentage of green area (%GA) and b) NDVI. We combined exposure data with Barcelona-specific mental health risk estimates, adult population (n = 1,235,375), and mental health data, and calculated preventable cases.

FINDINGS

Under the Eixos Verds Plan, we estimated an average increase of 5·67 %GA (range: 0·00% - 15·77%) and 0·059 NDVI (range: 0·000 - 0·312). We estimated that with the Eixos Verds Plan implementation, 31,353 (95%CI: 18,126-42,882) cases of self-perceived poor mental health (14·03% of total), 16,800 (95%CI: 6828-25,700) visits to mental health specialists (13·37% of total), 13,375 (95%CI: 6107-19,184) cases of antidepressant use (13·37% of total), and 9476 (95%CI: 802-16,391) cases of tranquilliser/ sedative use (8·11% of total) could be prevented annually, along corresponding to over 45 M € annual savings in mental health costs annually.

INTERPRETATION

Our results highlight the importance of urban greening as a public health tool to improve mental health in cities. Similar results for green interventions in other cities could be expected.

Cooling cities through urban green infrastructure: a health impact assessment of European cities

BACKGROUND

High ambient temperatures are associated with many health effects, including premature mortality. The combination of global warming due to climate change and the expansion of the global built environment mean that the intensification of urban heat islands (UHIs) is expected, accompanied by adverse effects on population health. Urban green infrastructure can reduce local temperatures. We aimed to estimate the mortality burden that could be attributed to UHIs and the mortality burden that would be prevented by increasing urban tree coverage in 93 European cities.

METHODS

We did a quantitative health impact assessment for summer (June 1-Aug 31), 2015, of the effect of UHIs on all-cause mortality for adults aged 20 years or older in 93 European cities. We also estimated the temperature reductions that would result from increasing tree coverage to 30% for each city and estimated the number of deaths that could be potentially prevented as a result. We did all analyses at a high-resolution grid-cell level (250 × 250 m). We propagated uncertainties in input analyses by using Monte Carlo simulations to obtain point estimates and 95% CIs. We also did sensitivity analyses to test the robustness of our estimates.

FINDINGS

The population-weighted mean city temperature increase due to UHI effects was 1·5°C (SD 0·5; range 0·5-3·0). Overall, 6700 (95% CI 5254-8162) premature deaths could be attributable to the effects of UHIs (corresponding to around 4·33% [95% CI 3·37-5·28] of all summer deaths). We estimated that increasing tree coverage to 30% would cool cities by a mean of 0·4°C (SD 0·2; range 0·0-1·3). We also estimated that 2644 (95% CI 2444-2824) premature deaths could be prevented by increasing city tree coverage to 30%, corresponding to 1·84% (1·69-1·97) of all summer deaths.

INTERPRETATION

Our results showed the deleterious effects of UHIs on mortality and highlighted the health benefits of increasing tree coverage to cool urban environments, which would also result in more sustainable and climate-resilient cities.

FUNDING

GoGreenRoutes, Spanish Ministry of Science and Innovation, Institute for Global Health, UK Medical Research Council, European Union's Horizon 2020 Project Exhaustion.

The evaluation of the 3-30-300 green space rule and mental health

BACKGROUND AND AIMS

Urban green space has many health benefits, but it is still unclear how much actually is needed for better health. Recently a new 3-30-300 rule of thumb for urban forestry and urban greening has been proposed, but this rule has not been evaluated for benefits on health. The rule requires that every citizen should be able to see at least three trees from their home, have 30 percent tree canopy cover in their neighbourhood and not live more than 300 m away from the nearest park or green space. The aim of this study was to evaluate the relationship between the 3-30-300 green space rule and its components in relation to mental health.

METHODS

We conducted a cross-sectional study based on a population-based sample of 3145 individuals aged 15-97 years from in Barcelona, Spain who participated in the Barcelona Health Survey (2016-2017). We created 3-30-300 green space indicators using questionnaire data, GIS, remote sensing and land cover maps. Mental health status was assessed with the 12-item General Health Questionnaire (GHQ-12) and also the use of tranquilizer/sedatives or antidepressants and psychiatrist or psychologist visits. Analyses were conducted using mixed effects logistic regression models with districts as the random effect, adjusted for relevant covariates.

RESULTS

We found that people in Barcelona had relatively little exposure to green space, whether through window view, living in an area with sufficient greenness, or access to a major green space, and only 4.7% met a surrogate 3-30-300 green space rule. Residential surrounding greenness, but not tree window view or access to major green space, was significantly associated with better mental health, less medication use, and fewer psychologist or psychiatrist visits. Meeting the full surrogate 3-30-300 green space rule was associated with better mental health, less medication use, and fewer psychologist or psychiatrist visits, but only for the latter combined the association was statistically significant (Odds ratio = 0.31, 95% CI: 0.11, 0.91).

CONCLUSION

Few people achieved the 3-30-300 green space in Barcelona and we used a surrogate measure. We observed health benefits when the full surrogate rule was met.

The impact of urban environmental exposures on health: An assessment of the attributable mortality burden in Sao Paulo city, Brazil

BACKGROUND

Currently, more than half of the global population lives in cities. Contemporary urban planning practices result in environmental risk factors (e.g. air pollution, noise, lack of green space, excess heat) that put health and well-being of city dwellers at risk and contribute to chronic diseases and premature death. Despite a growing body of evidence on adverse health impacts related to current urban and transport planning practices, especially for cities in the Global North, not much is known about associated health impacts in South American cities. Therefore, we estimated the mortality burden attributable to breaching internationally-recommended or locally-preferable exposure levels of urban planning related environmental exposures in Sao Paulo, Brazil.

METHODS

We carried out a health impact assessment study, following the comparative risk assessment framework, to assess preventable mortality impacts of breaching exposure recommendations for air pollution, green spaces and temperature at the census tract (CT) level (n = 18,363). We also assessed the distribution thereof by socioeconomic vulnerability.

RESULTS

We estimated that annually 11,372 (95% CI: 7921; 15,910) attributable deaths could be prevented by complying with recommended exposure levels. The largest proportion of preventable mortality was due to breaching air pollution limits (i.e. 8409 attributable deaths), followed by insufficient green space (i.e. 2593), and excess heat (i.e. 370). Adverse health impacts were larger in CTs of lower socioeconomic vulnerability, due to demographic profile, traffic density and residential area configurations.

DISCUSSION

Not complying with the health limits for air pollution, green space and temperature exposures resulted in a considerable preventable mortality burden (i.e. 17% of total expected deaths) in Sao Paulo. This burden can be reduced by improving current urban and transport planning practices.

Study protocol of the European Urban Burden of Disease Project: a health impact assessment study

INTRODUCTION

Cities have long been known to be society's predominant engine of innovation and wealth creation, yet they are also hotspots of pollution and disease partly due to current urban and transport practices. The aim of the European Urban Burden of Disease project is to evaluate the health burden and its determinants related to current and future potential urban and transport planning practices and related exposures in European cities and make this evidence available for policy and decision making for healthy and sustainable futures.

METHODS AND ANALYSIS

Drawing on an established comparative risk assessment methodology (ie, Urban and Transport Planning Health Impact Assessment) tool), in nearly 1000 European cities we will (1) quantify the health impacts of current urban and transport planning related exposures (eg, air pollution, noise, excess heat, lack of green space) (2) and evaluate the relationship between current levels of exposure, health impacts and city characteristics (eg, size, density, design, mobility) (3) rank and compare the cities based on exposure levels and the health impacts, (4) in a number of selected cities assess in-depth the linkages between urban and transport planning, environment, physical activity and health, and model the health impacts of alternative and realistic urban and transport planning scenarios, and, finally, (5) construct a healthy city index and set up an effective knowledge translation hub to generate impact in society and policy.

ETHICS AND DISSEMINATION

All data to be used in the project are publicly available data and do not need ethics approval. We will request consent for personal data on opinions and views and create data agreements for those providing information on current and future urban and transport planning scenarios.For dissemination and to generate impact, we will create a knowledge translation hub with information tailored to various stakeholders.

Green space and mortality in European cities: a health impact assessment study

BACKGROUND

Natural outdoor environments including green spaces play an important role in preserving population health and wellbeing in cities, but the number of deaths that could be prevented by increasing green space in European cities is not known. We aimed to estimate the number of natural-cause deaths among adult residents that could be prevented in cities in 31 European countries, if the WHO recommendation for universal access to green space was achieved.

METHODS

In this health impact assessment study we focused on adult residents (aged ≥20 years; n=169 134 322) in 978 cities and 49 greater cities, in 31 European countries. We used two green space proxies: normalised difference vegetation index (NDVI), and percentage of green area (%GA). The exposure was estimated at a fine grid-cell level (250 m × 250 m) and the preventable mortality burden for 2015 was estimated at the local city-level.

FINDINGS

For 2015 we found that meeting the WHO recommendation of access to green space could prevent 42 968 (95% CI 32 296-64 177) deaths annually using the NDVI proxy (ie, 20% [95% CI 15-30] of deaths per 100 000 inhabitants-year), which represents 2·3% (95% CI 1·7-3·4) of the total natural-cause mortality and 245 (95% CI 184-366) years of life lost per 100 000 inhabitants-year. For the %GA proxy 17 947 (95%CI 0-35 747) deaths could be prevented annually. For %GA the number of attributable deaths were half of that of the NDVI and results were non-significant due to the exposure response function considered. The distribution of NDVI and %GA varied between cities and was not equally distributed within cities. Among European capitals, Athens, Brussels, Budapest, Copenhagen, and Riga showed some of the highest mortality burdens due to the lack of green space. The main source of uncertainty for our results was the choice of the age-structures of the population for the NDVI analysis, and exposure-response function for the %GA analysis.

INTERPRETATION

A large number of premature deaths in European cities could be prevented by increasing exposure to green space, while contributing to sustainable, liveable and healthy cities.

FUNDING

GoGreenRoutes, Internal ISGlobal fund, and the United States Department of Agriculture Forest Service.

The impact of urban and transport planning on health: Assessment of the attributable mortality burden in Madrid and Barcelona and its distribution by socioeconomic status

BACKGROUND

The population living in urban areas is growing rapidly. The level of exposure to adverse environmental factors is detrimental to human health and is directly related to urban and transport planning practices.

OBJECTIVE

To estimate the premature mortality burden of non-compliance with international exposure guidelines for air pollution, noise, access to green space and heat for Barcelona and Madrid (Spain), and its distribution among the population by the socioeconomic status (SES).

METHODS

The Urban and TranspOrt planning Health Impact Assessment (UTOPHIA) tool was applied and the attributable premature mortality due to non-compliance with recommended exposure levels was estimated. The distribution of the attributable mortality burden among the population by SES was investigated through Generalized Additive Models (GAMs) adjusting for spatial autocorrelation and a cluster analysis was performed to identify attributable mortality hot spots.

RESULTS

Annually, 7.1% and 3.4% of premature mortality in Barcelona and Madrid, respectively, could be attributed to non-compliance with the international exposure recommendations for air pollution, noise, heat and access to green space. In addition, analysis by SES showed that in Barcelona lower SES areas had an overall greater attributable mortality rate, while in Madrid, the distribution of the attributable mortality burden by SES varied by exposure.

CONCLUSION

This study shows the impact of environmental exposures on mortality and highlights the importance of taking integrated actions when designing cities considering the health impacts, but also the specificities of each city such as the socio-demographic context. Moreover, the high precision scale of the analysis enables the identification of environmental hazards and mortality hot spots providing a powerful tool to support priority-setting and guide policymakers towards a healthy, sustainable and just city for all of their residents.

Neurofibromatosis type I with periodontal manifestation. A case report and literature review

The term neurofibromatosis (NF) is used for a group of genetic disorders that primarily affect the cell growth of neural tissues. Neurofibromatosis type 1 (NF1), also known as von Recklinghausen's disease, is the most common type of NF and accounts for about 90% of all cases. It is one of the most frequent human genetic diseases, with a prevalence of one case in 3,000 births. The expressivity of NF1 is extremely variable, with manifestations ranging from mild lesions to several complications and functional impairment. Oral manifestations can be found in almost 72% of NF1 patients. A case of a NF1 patient with a gingival neurofibroma in the attached gingiva of the lingual aspect of the lower central incisors is presented. The lesion was nodular, with sessile base, non-ulcerated, non-painful, with normal colour and measured 1 cm in diameter. An excisional biopsy of the oral lesion was performed. Histopathological and immunohistochemical analysis confirmed the clinical hypothesis of neurofibroma. Because NF1 is one of the most common genetic diseases and oral manifestations are very common, dentists should be aware of the characteristics of this disease.

Identification of growth hormone receptor in localised neurofibromas of patients with neurofibromatosis type 1

BACKGROUND

The hallmark of neurofibromatosis type 1 (NF1) is the development of multiple neurofibromas. Solitary neurofibroma may occur in an individual who does not have NF1, but multiple neurofibromas tend to develop only in those with NF1. It has been suggested that hormones may influence the neurofibromas of patients with NF1. The evidence that hormones may influence the growth of neurofibromas comes mainly from the observation that localised neurofibromas of patients with NF1 commonly grow during puberty and pregnancy. Because growth hormone (GH) concentrations increase during puberty, it is possible that GH influences the growth of these tumours.

AIMS

To investigate the presence of GH receptors (GHRs) in neurofibromas.

METHODS

By means of immunohistochemistry, the presence of GHRs was investigated in two groups of patients: 16 patients without NF1 with solitary neurofibromas (group A) and 10 patients with NF1 with localised neurofibromas (group B).

RESULTS

Six of the 16 patients in group A had neurofibromas that were immunopositive for GHR, whereas nine of the 10 patients in group B were immunopositive.

CONCLUSIONS

Most patients with NF1 have localised neurofibromas that express GHR. This suggests that GH may play some role in the development of localised neurofibromas in patients with NF1.

Implant-retained removable prosthesis with ball attachments in partially edentulous maxilla

This clinical report presents a restorative option for the partially edentulous maxilla utilizing an implant-retained removable partial denture without retentive clasps. This approach required (1) fewer patient visits and laboratory procedures; (2) the use of minimal number of implants; (3) lower financial obligations; and (4) no sinus elevation surgery. The use of O-ring attachments provided excellent retention and stability. The detachable prosthesis over implants allows easier oral hygiene by the patient and provides superior esthetics and phonetics in cases involving advanced ridge resorption.

Treatment of a human transosseous mandibular defect by guided bone regeneration

The treatment of through-and-through human periapical lesions by barrier membrane techniques has not been reported in the periodontal literature. However, periodontists frequently perform this treatment. The authors present a case that demonstrates radiopacity after regeneration surgery of a human periapical transosseous mandibular defect, suggesting local bone regeneration. The surgical technique performed in this case was based on the principles of guided bone regeneration using a demineralized freeze-dried bone membrane (DFDBM). The bone membrane acted as an efficient barrier that excluded the nonosteogenic tissue. Radiographic findings demonstrated bone fill after 8 months.

Ridge augmentation following implantation of recombinant human bone morphogenetic protein-2 in the dog

BACKGROUND

Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier induces bone for reconstruction of skeletal defects. The rhBMP-2/ACS implant is prepared by administering a rhBMP-2 solution to dry ACS. Once prepared, rhBMP-2/ACS forms a moldable, cohesive, and adhesive implant. However, rhBMP-2/ACS does not have sufficient structural strength to withstand soft tissue compression at specific anatomic sites. To more fully understand the mechanisms that affect bone induction by rhBMP-2/ACS in the presence of soft tissue compression, it would be useful to have a preclinical model that appropriately simulates such circumstances in patients. This pilot study evaluated one such potential model.

METHODS

Bilateral, Class III alveolar defects were surgically produced in 4 adult mongrel dogs following extraction of the mandibular fourth premolars and reduction of the alveolar ridge. After an 8-week healing interval, mucoperiosteal flaps were elevated and rhBMP-2/ACS or rhBMP-2/ACS combined with hydroxyapatite (HA) was implanted into contralateral defects. The animals were euthanized at 12 weeks post-augmentation and block biopsies processed for histologic evaluation.

RESULTS

Limited augmentation followed implantation of rhBMP-2/ACS (0.7 +/- 0.6 mm). In contrast, sites receiving rhBMP-2/ACS/HA exhibited clinically relevant ridge augmentation (5.5 +/- 1.6 mm). Defects implanted with rhBMP-2/ACS exhibited dense trabeculation within the corpus of the reduced alveolar process. The cortices appeared intact without evidence of expansion into the defect area. Three defects receiving rhBMP-2/ACS/HA exhibited sparse bone trabeculae amidst HA particles, fibrovascular tissue, and marrow. Commonly, the HA particles were encapsulated by fibrous tissue. Some particles were observed in contact with bone.

CONCLUSIONS

The results suggests that rhBMP-2/ACS has limited effect alone in this augmentation model of Class III alveolar ridge defects. Inclusion of HA into the rhBMP-2 construct results in clinically relevant augmentation, however, the quality of bone is compromised.

Localized ridge maintenance using bone membrane

The immediate placement of a dental implant into a fresh extraction socket has been limited in many instances by the quantity of bone that remains after the extraction. This article presents two clinical cases that demonstrate successful regeneration of alveolar ridges in which there was extensive loss of the buccal plate of bone. This lack of alveolar process impeded the immediate placement of dental implants into fresh extraction sockets. The surgical technique performed in these cases was based on the principles of guided bone regeneration using a demineralized freeze-dried bone membrane. The bone membrane acted as an efficient barrier that excluded the nonosteogenic tissues. Bone formation took place for the placement of endosseous dental implants 8 months after the procedures were initiated. These human clinical cases confirm positive results of previous animal findings.

Clinical and histologic evaluation of the demineralized freeze-dried bone membrane used for ridge augmentation

The biologic principle of guided bone regeneration has been successfully used to regenerate alveolar ridges. The objective of this pilot study was to clinically and histologically evaluate the demineralized freeze-dried bone membrane. Four premolar teeth were extracted from two dogs, and the remaining alveolar bone was surgically reduced in width and height to produce Class III ridge defects. After a 2-month healing period, mucoperiosteal flaps were elevated, and demineralized freeze-dried cortical columns were used as space maintainers. Bone membranes were used as barriers. The animals were sacrificed at 3 months and the surgical areas were recovered and processed for histologic evaluation. Results showed ridge augmentation in all sites. Clinically, the augmented areas appeared to have the same hardness as the surrounding bone on the periphery of the experimental site. After elevation of a mucoperiosteal flap, the bone membrane could be seen. Histologically, the bone membrane acted as an efficient barrier, excluding the nonosteogenic tissues. New bone formation underneath the membrane was found in all specimens. This study suggests that a bone membrane in combination with a space maintainer can guide new bone formation to regenerate localized chronic alveolar ridge defects.

Clinical comparison of cellulose and expanded polytetrafluoroethylene membranes in the treatment of class II furcations in mandibular molars with 6-month re-entry

The present study compared two barrier membranes, ePTFE and cellulose, used to treat Class II furcations in mandibular molars. Fifteen patients with no history of systemic diseases and presenting matched pair defects were selected. The following soft tissue measurements were taken at baseline (after the hygienic phase), and 6 months after surgery: gingival recession, probing depth, clinical attachment level, and width of keratinized tissue. At the time of membrane placement, and 6 months later (re-entry), the following hard tissue parameters were recorded: cemento-enamel junction (CEJ) to alveolar crest, CEJ to base of osseous defect, alveolar crest to base of osseous defect, and horizontal defect depth. According to the surgical protocol, the ePTFE membranes were completely covered by the flaps (subgingival placement), whereas the cellulose membranes extended 1 mm coronal to the gingival margin (supragingival placement). Healing was uneventful in all cases and membranes remained in place for 4 weeks. Data were analyzed using the Wilcoxon signed-rank test at the 5% level of significance. No statistically significant differences were found between the ePTFE and cellulose membranes, respectively (in mm): probing depth reduction (2.87+/-1.0 versus 3.27+/-1.1), gain in attachment level (2.53+/-1.2 versus 2.8+/-1.3), defect fill (3.0+/-1.4 versus 4.0+/-2.3), horizontal furcation fill (2.87+/-1.1 versus 2.93+/-1.0), alveolar crest resorption (2.4+/-10 versus 2.73+/-1.2), and intrabony defect fill (0.6+/-1.2 versus 1.27+/-1.7). We conclude that both ePTFE and cellulose membranes are effective, not showing statistical differences in efficacy. A larger study may be necessary to show differences in efficacy and adverse effects.

A new approach to regeneration of surgically reduced alveolar ridges in dogs: a clinical and histologic study

Premolar teeth were extracted from dogs and the remaining alveolar bone was surgically reduced to produce Class III ridge defects. Following 2 months of healing, a new technique using allogeneic cortical columns to prop up the raised mucoperiosteal flaps and create space for developing tissue was employed to create space for regeneration of the ridges. In the control sites, the cortical columns alone were used to prop up the mucoperiosteal flap; whereas in the experimental sites, barrier membranes (expanded polytetrafluoroethylene or bone membranes) were interposed between the flaps and the projecting cortical columns. In alternate sites, decalcified allogeneic freeze-dried particulate bone was added to fill the voids between the cortical columns, the underlying host bone, and the membranes. Variations of the new approach that were based on the principles of guided tissue regeneration provided the most significant gains in ridge width, with a mean aggregate gain of 3.31 mm. Histologically, all variations of the basic technique were seen to have augmented the surgically reduced ridges. Osseous regeneration was observed only where the barrier membranes were used. The addition of particulate bone filler did not appear to offer any advantage. This new approach to ridge augmentation meets the requirements for alveolar ridge regeneration.