Crown Coverage Research Articles

The protective role of canopy cover against cork oak decline in the face of climate change

Abstract Cork oak (Quercus suber L.) mortality has reached alarming proportions in the last decades, exacerbated by climate change. Understanding this phenomenon is crucial in finding mitigation or adaptation strategies. This study conducts a diachronic analysis of cork oak mortality over 10 years using GIS (Geographic Information Systems) tools, focusing on Portugal’s Tagus Lezíria region. Topographic, edaphic and climatic variables were employed to create maps of edaphoclimatic aptitude for cork oaks. Dead trees were identified using remote sensing techniques and crown coverage was determined to calculate the trees’ mortality index. The diachronic analysis aimed the exploration of climate change effects on cork oak mortality. A decrease in precipitation was observed, significantly impacting stands with canopy cover below 40%. Furthermore, a negative effect of solar radiation identified only in stands with canopy cover of 40% suggested its role in cork oak decline. This study introduces a novel perspective, highlighting the protective effect of denser canopy cover against excessive solar radiation and the impact of reduced precipitation. The integrated and diachronic approach provides valuable information for adapting management strategies to climate change challenges.

Quality Assessment and Comparison of 3D-Printed and Milled Zirconia Anterior Crowns and Veneers: In Vitro Pilot Study

AbstractThe esthetic rehabilitation of a patient is a demanding yet rewarding procedure, improving the form, function, and well-being of a patient. Three-dimensional (3D) printed, or additive manufactured, zirconia has recently entered the dental space, but without a thorough assessment or comparison. This pilot study utilized digital impressions of two demonstration casts: Cast 1 prepared both central incisors for full ceramic crown coverage, while cast 2 had a lateral incisor (#22) prepared for a ceramic veneer. Both casts underwent digital scanning (Straumann CARES 3, Straumann, Basel, Switzerland) to create virtual STL models. Cast 1 had two full zirconia anterior crowns digitally designed, and Cast 2 had a zirconia veneer digitally designed, using Exocad GmbH software by a certified dental technician at Schulich Dentistry. The STL files were used for fabricating six milled zirconia crowns for central incisor (#21) and six 3D-printed zirconia crowns for the other central incisor (#11). Similarly, for Cast 2, milled and 3D-printed zirconia veneers were made for the prepared lateral incisor (#22). Statistical analysis employed Minitab 16.1.0 software to construct a 2 × 2 table for cross-tabulation and chi-squared analysis. This statistical approach assessed the relationship between restoration design and processing method. Cochran–Mantel–Haenszel test evaluated categorical variables considering different classification variables. Milled restorations showed minor variations, while 3D-printed units displayed consistency. Statistical tests found no significant associations. This in vitro study suggests 3D-printed zirconia for crowns and veneers meets precementation standards akin to conventionally milled restorations. Further research can assess its potential benefits for dentistry's efficiency, cost, and sustainability.

Terrestrial laser scanning vs. manual methods for assessing complex forest stand structure: a comparative analysis on plenter forests

In continuous cover forestry, plenter silviculture is regarded as an elaborated system for optimizing the sustainable production of high-quality timber maintaining a constant but heterogeneous canopy. Its complexity necessitates high silvicultural expertise and a detailed assessment of forest stand structural variables. Terrestrial laser scanning (TLS) can offer reliable techniques for long-term tree mapping, volume calculation, and stand variables assessment in complex forest structures. We conducted surveys using both automated TLS and conventional manual methods (CMM) on two plots with contrasting silvicultural regimes within the Black Forest, Germany. Variations in automated tree detection and stand variables were greater between different TLS surveys than with CMM. TLS detected an average of 523 tree stems per hectare, while CMM counted 516. Approximately 9.6% of trees identified with TLS were commission errors, with 6.5% of CMM trees being omitted using TLS. Basal area per hectare was slightly higher in TLS (38.9 m3) than in CMM (38.2 m3). However, CMM recorded a greater standing volume (492.7 m3) than TLS (440.5 m3). The discrepancy in stand volume between methods was primarily due to TLS underestimating tree height, especially for taller trees. DBH bias was minor at 1 cm between methods. Repeated TLS inventories successfully matched an average of 424 tree positions per hectare. While TLS adequately characterizes complex plenter forest structures, we propose enhancing this methodology with personal laser scanning to optimize crown coverage and efficiency and direct volume measurements for increased accuracy of wood volume estimations. Additionally, utilizing 3D point cloud data-derived metrics, such as structural complexity indices, can further enhance plenter forest management.

Potato late blight severity monitoring based on the relief-mRmR algorithm with dual-drone cooperation

Late Blight in Potato, a prevalent potato disease, significantly impacts potato yield and stands as one of the principal afflictions affecting the potato crop. Timely and effective monitoring of late blight severity in potato and its spatial distribution has become an immediate priority. In this study, we employed a dual-drone collaborative approach, utilizing the multispectral drone from DJI as well as an ultra-high-resolution RGB drone. By integrating the vegetation index derived from the multispectral UAV, the texture index from the RGB drone, and the estimated crown coverage feature, we combined the relief-mRmR technique with machine learning modeling algorithms to monitor late blight in potato. We compared and constructed severity monitoring models for late blight in potato using Support Vector Machine (SVM), Random Forest (RF), and K-Nearest Neighbors (KNN) classification algorithms. The results indicate that the RF model exhibited the highest accuracy. For the training dataset, the overall accuracy (OA) and kappa coefficient were 92.50% and 0.90, respectively, while for the independent validation dataset, the OA and kappa coefficient reached 97.50% and 0.96, respectively. The findings also demonstrate that augmenting the vegetation index and texture index with the estimated high-resolution plant crown coverage information significantly enhances the accuracy of the late blight in potato monitoring model.

Evaluation of clones of Eucalyptus planted in an experimental plot for Forest Landscape Restoration in Paraguay

The adoption of strategies involving the combination of Eucalyptus plantations with native species emerges as an effective alternative to mitigate the issues of deforestation, degradation, and fragmentation affecting native forests. Eucalyptus, in this context, presents itself as a species that offers a rapid economic return, making it an appealing resource for private landowners aiming to carry out land restoration processes. The aim of this study was to compare the growth in diameter at breast height, diameter at collar height, crown coverage area, and height of the Eucalyptus urophylla S.T. Blake × Eucalyptus grandis W. Hill (clone i144) and Eucalyptus urophylla S.T. Blake × Eucalyptus camaldulensis Dehnh. (Clone vm01) hybrids. The study was conducted in the district of Hernandarias, Alto Paraná Department, Paraguay. It was structured into 5 blocks and 2 treatments randomly distributed. Both treatments were selected for this study, with the first treatment consisting of a strip of eucalyptus for timber purposes, and the second treatment serving energy purposes. The design of each experimental unit comprised two major strips, one for conservation and the other for production. The focus of the study was on the second strip, which included 32 trees per experimental unit on treatment 1, and the second treatment, with 44 trees, covering an area of 1080 m2 per unit. The parameters evaluated for this study were as follows: diameter at collar height (DAC), total height (Ht), Diameter at breast height (DAP), and crown coverage area (ACP) over a 24-month plantation period. Statistically, no significant differences were found in the analyzed variables; on average, it was determined that the means were 1167.3 cm, 11 cm, 3.9 m2, 132.3 cm for Ht, DAP, ACP, and DAC, respectively.

Strength and Surface Characteristics of 3D-Printed Resin Crowns for the Primary Molars.

Some resin polymers available for three-dimensional (3D) printing are slightly elastic, which may be advantageous when used for full crown coverage of the primary teeth. This study was performed to evaluate the mechanical properties of two types of 3D-printed resin crowns in terms of strength and surface characteristics. Polymer resins used for temporary crowns (TCs) and temporary flexible dentures (TFDs) were tested. Digitally designed crowns with different thicknesses (0.4 and 0.6 mm) were 3D-printed. Milled zirconia crowns were used as the control. The static and dynamic fracture loads of the crowns were measured. The crown surface was evaluated using scanning electron microscopy. The average strength did not differ between the types of crowns. The differences between the dynamic and static fracture loads were insignificant. In the TC group, thicker crowns showed lower strength both under static and dynamic loads. After thermomechanical loading, microcracks and dropouts of macrofillers were detected on the surface of all types of resin crowns. The deposition of abraded debris occurred more in the TFD group. The 3D-printed resin crowns were thought to endure biting forces in children. However, some limitations of the material itself should be improved for consideration as a new treatment option in pediatric dentistry.

Administrative Plan for Reforestation of the Nineveh Forest for the Period 2019-2029

Forests are a moving ecosystem, so it is in a state of continuous movement with time due to the entry of new elements and the exit of others as a result of physiological death or cutting as a result of human activities, from that we see that the forest is in a state of continuous change in the area of the crown coverage of its trees, so the trees of the Nineveh forest include many species Trees, and eucalyptus trees are the largest part, and these trees were exposed to many environmental and social symptoms that led to their decline and affected their trees to a large extent, which requires identifying these changes during the last period, through the use of a space statement of the Landsat satellite for two periods of time (2010-2018) M, to prepare maps to extract information about the disturbances that occurred in the past, which led to their decline. In this study, we used nearly a decade of data to derive an estimate of the spatial changes that occurred in the forest trees of Nineveh. We have shown the area of crown coverage of trees for the two time periods, and the area of crown coverage in 2010 AD was 116.51 hectares, while the area of crown coverage in 2018 AD was 109.27 hectares. The area of the forest and the spatial area of the species change significantly for the different types of trees in the forest.

Comparative FEM study about various posts used on endodontically treated teeth

Objectives. The aim of the present study was to analyze comparatively, through the finite element method (FEM), the biomechanical behavior of different types of devices used to increase the resistance of restorations on endodontically treated teeth, upon the experimental application of a force of 350N. Materials and methods. We studied comparatively three types of posts, respectively: fiberglass post, cast post from Cr-Co-Mo alloy and prefabricated titanium post. Three irretrievable extracted teeth for periodontal reasons were endodontically treated and then specifically prepared for cementation of this devices. The teeth were scanned at a radio-diagnostic center, and the obtained DICOM files were processed with MIMICS and 3-matic and then subjected to finite element analysis with ANSYS. Results. From the 48 simulations carried out for the case of all-ceramic crown coverage, the use of titanium post is associated with 25 situations in which maximum or minimum values appear, the use of cast post presents 12 situations in which maximum or minimum values are developed, the use of fiberglass posts is associated with 10 simulations where maximum or minimum values occur, and in one case the deformations are equal. Regarding the use of the zirconium oxide crown, the results are comparable. Conclusions. The presence of zirconium oxide crowns generally produces less valuable stresses and deformations at the level of the components. The stress and strain values are lowest when using fiberglass posts, followed closely by cast post and far behind by titanium post. In all simulated situations, the limit values of stresses and strains are mostly recorded at the tooth root, which is susceptible to fracture in case of parafunctional forces, followed by the three devices themselves and the covering crowns.

Impact of Crown Closure on Cone Production and Effective Number of Parents in Natural Stands of Taurus Cedar (Cedrus libani A. Rich.)

This study was carried out to estimate the effect of crown closure classes (degraded forest, low crown coverage, medium crown coverage, and full crown coverage) and growth characteristics (three heights, diameter at base, diameter at breast height, and crown diameter) on cone production and to estimate fertility variation and its allied parameters in 130-year-old natural populations of Taurus cedar, also called cedar of Lebanon (Cedrus libani A. Rich.). The effect of biotic (e.g., growth characteristics, crown closure) and abiotic (e.g., light penetration, temperature, humidity, and soil characteristics) factors on cone production, fertility variation, and gene diversity was evaluated in two consecutive years of Taurus cedar. The factors, viz., altitude, temperature, aspect, and rainfall, varied, while some of them could be managed by cultural operations such as management of the crown and stand density. The impact of crown closure on cone production, fertility variation, and related parameters were observed in Taurus cedar’s natural populations sampled from southern Turkey. Maximum cone productions of 29 and 40/tree were recorded with full crown closure in two consecutive years, due to significant differences among individuals within crown closure class. For instance, cone productions were between 10 and 67 in the full crown closure of the first year. The sibling coefficient, which is a measure of the fertility variation in a stand, was the highest (1.16) for the full crown closure in the first (meaning 86% fertile trees) and the second years (1.55, 65%), while it was the lowest for the medium crown closure (1.09, 92%) in both years. Gene diversity decreased from a degraded patch (0.987) to that with full crown closure (0.984). Results of variance analysis showed a significant (p ≤ 0.05) difference between crown closure classes for cone production within the second year and between years. Significant positive (p ≤ 0.05) correlations were noted between years for cone production (r = 0.22) and between cone production and crown closure in the first and second years (r = 0.29). However, growth characteristics had no effect on cone productions in individual crown closure classes, while there were significant (p ≤ 0.05) correlations between the diameter at breast height and cone production for both years (r = 0.15 and 0.17) in pooled populations.

Shear bond strength of dual-cured resin cements on zirconia: The light-blocking effect of a zirconia crown

The presence of restorative material between resin cement and the light-curing unit can reduce light transmission. This study aimed to evaluate the effect of the light-blocking effect of zirconia crown on shear bond strength (SBS) between three dual-cured resin cements and the zirconia surface. Sixty zirconia specimens were prepared and divided into three groups according to the type of resin cement [RXU (RelyX Ultimate); SC2 (SmartCem2); MEC (Maxcem Elite Chroma)]. Each group was further divided into two subgroups, with or without a 1-mm-thick zirconia crown (n=10). The specimens were light-cured from five different directions for 20s each. All specimens were thermocycled 5000 times and subjected to SBS testing, followed by scanning electron microscope examination. The presence of a 1-mm-thick zirconia crown had no significant effect on the SBS in all resin cements. However, the SBS was significantly affected by type of resin cement. RXU showed the highest SBS (8.35MPa with crown; 8.57MPa without crown), followed by SC2 (5.48MPa with crown; 5.57 without crown) and then MEC (3.37MPa with crown; 4.04MPa without crown. Fractured surfaces exhibited varying degrees of mixed failure patterns. A 1-mm-thick zirconia crown material between the light source and the dual-cured resin cement did not significantly influence the SBS of the resin cements on the zirconia substrates. RXU exhibited the highest SBS regardless of zirconia crown coverage. With sufficient light-curing, dual-cured resin cements can be a good choice for zirconia crown cementation.

Assessment of Past Decadal Dynamics of Tree Stands in Forest–Tundra Transition Zone on the Polar Ural Mountains Calibrated Using Historical and Modern Field Measurements

Altitudinal forest limits are typically climatically dependent, such that increasing temperatures connected to global warming are causing upslope shifts in treeline ecotones worldwide. However, at the local and regional levels, the degree of such a response is dependent on differences in climate, topography and soil features. In recent decades, attempts have been undertaken to estimate tree stand dynamics with remote sensing methods, but their resolution is still too coarse for a precise assessment of stand structural changes, and requires ground-truthing, which is not possible without historical data collected on a single-tree level. We used aerial photos (1962) and satellite images (2021) in combination with historical inventory data to investigate changes in open forest positions at different spatial scales at the eastern macroslope of the Polar Urals over the past 60 years. Additionally, obtained remote sensing data were validated on a single-slope level using tree crown size estimations. Our investigations showed that since 1960 up to present day, the total crown coverage increased from 6.9 to 22.1% within the test polygon. A highly spatially variable upslope advance in an open forest boundary was identified from 1.7 up to 7.1 m in altitude per decade. We revealed that the rate of tree stand transformations was to a great extent depended on the stand density in the 1960s, soil substrate type, moisture regime, slope aspect and inclination. Our results highlighted the necessity to consider the abovementioned factors when trying to predict climate-induced tree distributional responses in subarctic mountain regions.

Chances and Limitations of Mixed Oak Regeneration under Continuous Canopy Cover—Evidence from Long-Term Observations

Traditionally, due to its light ecology, oak is regenerated on clear cuts or areas where the crown coverage is heavily reduced. Thus, the regeneration phase is relatively short. Recently, selective long-term regeneration phases avoiding large gaps in the canopy but fostering mixed-species stands have been advocated as being more in keeping with close-to-nature forestry in Central European forests. However, examples of the successful regeneration of oak in mixtures following this type of regeneration are largely missing. Here, we report the results of long-term experiments located in three different forest types, where oak was long-term regenerated under different mixing and canopy cover situations. The observation periods reached from 26 to 36 years. We focused on the dynamics of stem number reduction, as well as the height and biomass development of oaks and their interaction with interspecific competition and canopy density. The probability of oaks occurring in the regeneration basically decreased over the duration of the regeneration period. Despite this, considerable regeneration biomass growth could be observed, especially in the case of the lower standing volume of the mature stand. The development of beech as the main competitor is scarcely slowed down by the canopy cover compared to oak. Increasing canopy cover noticeably impeded oak regeneration in the considered mixed stands. The model results suggest that a reduction in competition within the regeneration by lowering the proportion of beech below 30% enhanced the success of oak regeneration in the long run even in small patches. The productivity of the remaining stand was primarily driven by standing volume. However, a negative trend of its productivity emerged with high regeneration biomasses. The study results show that small-scale oak regeneration with prolonged regeneration duration is possible in principle. However, oak regeneration requires active and continuous silvicultural assistance, which has to be adjusted to the specific site conditions.

Aesthetic Restoration of Traumatized Deciduous Anterior Teeth Using Custom Fabricated Zirconia Crowns - A Case Report

Loss of anterior teeth in children can adversely affect the aesthetics, decrease masticatory efficiency, cause speech disturbance and result in the development of parafunctional habits and psychological problems. There are various complete crown coverage restorations like polycarbonate crowns, stainless steel crowns (SSC), open-faced SSC, commercially veneered SSC, Figaro crowns and Zirconia crowns. The superior aesthetics, inertness, and biocompatibility of ceramics have made them acceptable as a dental restorative material by clinicians. Zirconia ceramics have become a frequently employed biomaterial in dentistry due to their enhanced aesthetics and mechanical properties.
 The aesthetic management of decayed and traumatized deciduous anterior teeth using complete coverage restoration in children is strenuous owing to their limited size, proximity to the pulp, decreased surface area for bonding, teeth isolation difficulties and lack of cooperation. Structural loss of anterior teeth affects aesthetics, impairs mastication and phonetics, causes eruption disturbance of permanent teeth and leads to the development of non-nutritive habits. This may result in a psychosocial crisis in the patient including reduced self-esteem.
 Full coronal restorations like polycarbonate crowns, strip crowns, and modifications of stainless-steel crowns including the open-faced and pre-veneered crowns are being used by clinicians to restore discoloured incisors. However, they are often associated with technical, functional, or aesthetic limitations. Over the past decades, advancement in different technologies in the sphere of dentistry and the immense booming of dental materials have always resulted in a continuous re-assessment of different treatment principles so employed. Paediatric zirconia crowns were introduced in 2010 and have gained popularity for aesthetic considerations.[1] Zirconia crowns are clinically justifiable and with greater parental gratification when compared with other full coverage coronal restorations. Zirconia crowns express high strength, aesthetics, durability, biocompatibility, reduced wear of opposing teeth, and cause less gingival irritation.

A framework for a forest ecological base map – An example from Norway

In the management of forest ecosystems, spatial information about the extent, condition and pressures are essential. In the current study, we present a framework for a remote sensing-based forest ecological base map covering Norway. Combining remotely sensed imagery from optical satellite systems such as Sentinel-2 and Landsat provides information about forest ecosystem extent and change over time. Utilizing a national dataset of airborne laser scanning (ALS) data allowed predicting a range of attributes describing forest condition, including naturalness. In total, seven definitions of naturalness were evaluated. Pressures on the forest ecosystems were mapped using a change detection algorithm and satellite data from 1986 to 2020. Change detection is the cornerstone in monitoring and for understanding the pressures on the ecosystems. The predicted forest extent had an overall accuracy of 85 to 89% using Sentinel-2 imagery from 2020 and 71 to 81% using Landsat imagery from 1986. For the forest condition attributes, the explained portion of the variances were >70% for biomass, height and volume and from 21% to 64% for number of stems, crown coverage and a diversity index. Naturalness was classified with accuracies of 77 to 98%, except for age-based definitions. Nevertheless, a large number of false positives were present. Change detection was evaluated in terms of final harvest and was identified with an overall accuracy of 84–92%. The land cover change classification had an overall accuracy of 70–92%. The detailed maps of forest condition and forest pressures were aggregated to a local level using model-based inference, providing estimates of mean values and uncertainty at a scale suitable for ecosystem indicator development. The collection of map layers describing forest extent, condition and pressures form a forest ecological base map important for environmental management.

Metabarcoding of canopy arthropods reveals negative impacts of forestry insecticides on community structure across multiple taxa

Abstract Insecticides used to combat outbreaks of forest defoliators can adversely affect non‐target arthropods. Forestry insecticides typically suppress Lepidoptera larvae which are the cornerstone of the canopy community of deciduous oak forests. The abrupt removal of this dominant component of the food web could have far‐reaching implications for forest ecosystems, yet it is rarely investigated in practice owing to several methodological shortcomings. The taxonomic impediment and the biased nature of arthropod sampling techniques particularly impede the assessment of insecticide impacts on diverse communities. To tackle this issue, we propose an experimental approach combining sampling by pyrethrum knockdown and species determination via DNA metabarcoding, using community subsampling to derive estimates of species abundances. We applied this protocol to investigate the short‐term effects of the insecticides diflubenzuron (DFB) and Bacillus thuringiensis var. kurstaki (BTK) on canopy‐dwelling arthropod communities in German oak woodlands. Our approach allowed us to detect most of the diversity and integrate species abundances in our analyses. By classifying arthropod species into assemblages based on their expected sensitivity rather than coarse taxonomic groupings, we could unveil substantial effects of DFB across multiple taxa 5 weeks after application. Although strong effects on single species appear related to direct toxicity, substantial impacts of DFB on parasitoids and xylophagous beetles suggest that anti‐defoliator treatments can have previously unsuspected indirect effects on some components of forest arthropod communities. The impacts of BTK on community structure were consistent with that of DFB though much weaker. Synthesis and applications. Comparing diversity patterns in the arthropod communities of sprayed and unsprayed oak canopies, our results show that selective insecticides can alter species diversity in presumably non‐sensitive taxa. Even though the ecological significance of these impacts has yet to be assessed in an operational setting, their existence calls for increased regulatory scrutiny on indirect effects. As community approaches become more attainable with the rapid development of DNA metabarcoding, we suggest the inclusion of community‐level end points as regulatory requirements for the approval of forest‐use insecticides.

Clumping Effects in Leaf Area Index Retrieval From Large-Footprint Full-Waveform LiDAR

Clumping effect denotes the nonrandomness of foliage. It deviates from the random distribution assumption of Beer’s law which is usually applied to leaf area index (LAI) retrieval from large-footprint full-waveform light detection and ranging (LiDAR). Some studies correct for large gaps-induced between-crown clumping, yet ignore the within-crown clumping. The error of LAI caused by these clumping effects and the influence of the forest structure parameters on them have not been quantitatively studied. This study quantified the between-crown, within-crown, and total clumping indices through a theoretical derivation, clarifying the mechanism of clumping; we used airborne LiDAR point clouds data in 11 290 footprints (diameter = 25 m) to estimate these indices in real forests. We found that: 1) the underestimation of LAI caused by directly applying Beer’s law could be up to 93%, and it decreases with fractional crown coverage but increases with crown length and leaf area density; 2) the method of correcting between-crown clumping improves LAI retrieval for cylindrical canopies effectively; however, 3) considerable underestimation (up to 58%) exists if we neglect the within-crown clumping for other canopies, which has not been realized before; and 4) both the between-crown and the within-crown clumping can be the dominant contributor, and the within-crown clumping was greater than the between-crown clumping in 47% of the studied footprints. In the two physically based LAI retrieval methods, Beer’s law has been commonly used due to its simplicity. Pathways to improve future LAI retrieval would be instrument improvement to capture the between-crown gaps and method study to correct the within-crown clumping further.

The influence of crown coverage on the accuracy of static guided implant surgery in partially edentulous models: An in vitro study

ObjectiveTo evaluate the influence of crown coverage of surgical guides on the accuracy of static computer-assisted implant surgeries (sCAISs) in different partially edentulous situations. MethodsAcrylic models with five types of partially edentulous situations were fabricated in this study. In coDiagnostiX software (Dental Wings, Montreal, Canada), surgical templates were designed and fabricated with reduced crown coverage (RCC), standard crown coverage (SCC) and extended crown coverage (ECC). Then, fully guided implant placement into the acrylic models was performed by dental surgeons with more than 10 years of experience. In total, 120 models and 120 guides were manufactured, and 168 bone-level Straumann replica implants (4.1 × 10 mm, Institut Straumann AG, Basel, Switzerland) were inserted. Postoperative implant positions were scanned (Trios 3, 3 shape, Copenhagen, Denmark) and compared with the preplanned virtual positions via coDiagnostiX (Dental Wings, Montreal, Canada). The angular, coronal and apical deviations were measured and analyzed to evaluate the accuracy of implant insertion. Statistical analysis was performed using one-way ANOVA and Tukey's test. ResultsFor single tooth missing situations, the RCC group was similar to the SCC group and ECC group in anterior sites. In premolar or molar sites, the SCC and ECC groups had no statistically significant difference (p > .05), while the RCC group had more coronal and apical deviation (p < .05). For multiple teeth missing situations, there was no difference among the RCC, SCC and ECC groups (p > .05). No difference was found among the five edentulous situations with different CCs (p > .05). ConclusionThe CC of templates can significantly affect the accuracy of guided surgeries when implants are inserted in a single gap at posterior sites. Templates with CC extended to the undercut line may be an optimal choice for static guided surgeries. Clinical significanceThe accuracy of static guided implant surgery can be influenced by the CC of templates, and proper CC with the guide covering extending to the undercut line may contribute to improved accuracy. CC should be taken into consideration when designing surgical templates.

Habitat use and conservation threats to Wild Water Buffalo Bubalus arnee (Mammalia: Artiodactyla: Bovidae) in Koshi Tappu Wildlife Reserve, Nepal

Wild Water Buffalo (WWB) Bubalus arnee is an endangered species and a protected animal in Nepal. The remaining WWB population is located in Koshi Tappu Wildlife Reserve (KTWR), and it appears to have low viability under prevailing conditions. We assessed the habitat use and conservation threats to wild water buffalo in KTWR. For habitat analysis the quadrant method was used. Eighty-four quadrants of 25 m2 for trees, 168 quadrants of 10m2 for shrubs and 336 quadrants of 1 m2 for herbs were laid out in the study area. Ivlev’s electivity index (IV) was calculated to assess the use of different habitat components. The important Value Index (IVI) was used for vegetation assessment. A relative threat ranking method was used to assess conservation threats for wild buffalo and their habitats. Wild buffalo mostly preferred habitats with distance to water resources less than 500 m (IV= 0.4), less than 25 % crown coverage (IV= 0.39) and more than 75 % ground coverage (IV= 0.42). The trees species Phyllanthus emblica, Acacia catechu, shrub species Mimosa pudica and the herb species Brachiaria distachya, Vetiveria zizanioides, Imperata cylindrica, and Saccharum spontaneum were preferred by WWB in the study area. Among the different plant categories, we found that Acacia catechu was the most preferred tree species (IVI= 156.95), Mimosa pudica the most preferred shrub species (IVI= 58.68), and Imperata cylindrica the most preferred herb species (IVI= 64.73). Major conservation threats perceived by local stakeholders for wild buffaloes were overgrazing by cattle and genetic swamping through crossbreeding with domestic buffalo. Therefore, conservation of grass species through control of grazing, and prevention of cross breeding are measures supported by this study. Additionally, site-specific conservation strategies should be adopted, based on identified threats in the study area.

Bird species richness across a Northern Andean city: Effects of size, shape, land cover, and vegetation of urban green spaces

Cities are human-dominated ecosystems where landscape transformation decreases biodiversity, a conservation concern when urbanization sprawls into biodiversity hotspots with high endemism. We aimed to evaluate the effects of site-specific features such as size and shape of green spaces, land cover, and vegetation on bird species richness in Medellín, Colombia, a city of Northern Andes (n = 44 urban green spaces sampled from February 2018 to February 2019). We found 255 plant species: 23 % of trees and 41 % of understory were native sensu stricto (local origin); most native species and individuals were in green spaces lacking vegetation management. Bird species richness (25.80 ± 8.05 resident species per sampling point; 83 resident species overall) increased towards larger and more regular-shaped urban green spaces (squared or rounded), with less percentage of impervious surfaces and more of grass–shrubs, and less influence of introduced trees in habitat structure (i.e. less crown coverage, basal area, and average height). Bird species richness also increased when richness or abundance of native understory vegetation sensu lato (local or regional origin) increased, but introduced trees dominance represented higher and most significant effects to explain bird species richness. Increasing edge effects across urban green spaces and human-related habitat transformation favoring non-native vegetation might represent significant constraints for enhancing local biodiversity in highly developed Andean cities.

Follow-up of Endodontically Treated Teeth Without Crown Coverage in Vidarbha Region

Statement of Problem: Teeth are weakened after endodontic treatment and should, preferably, be crowned, especially posterior teeth. However, this is not always possible due to certain reasons. Information about the appropriate treatment modalities. This retrospective study was carried out to evaluate the survival of endodontically treated teeth (ETTs) without crown coverage on the basis of various parameters in the region of Vidarbha in Maharashtra, India. Purpose: The aims of this cohort study were to evaluate the survival rate for endodontically treated molars without crown coverage and to identify possible related factors. Materials and Methods: Relevant data from 300 subjects for 148 ETTs was recorded at the Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College, Wardha, Maharashtra. Follow-up data were derived from a clinical examination and review of the dental record and radiographs. Subjects were not included in the study if teeth had provisional crowns, definitive restorations with cuspal coverage, or with dowel and core and/or crown restorations. The outcome evaluated was defined as a failure if there were negative findings in the condition of a tooth that required a restoration, tooth repair, or extraction. Tooth loss due to endodontic and periodontal reasons was excluded. The independent variables assessed were patient age, gender, location (maxilla or mandible), the existence of an opposing dentition and adjacent teeth, remaining tooth structure, and types of restorative material. One hundred and forty-eight teeth restored using glass-ionomer cement (GIC), SF, and composites were considered successful during the observation time of 3 years because no intervention was needed in these teeth were labeled as “survived.” The teeth restored with composite were 90. The teeth restored with GIC were 14. The teeth restored with silver amalgam were 44. Out of 148 teeth were considered successful during the observation time of 3 years because no intervention was needed in these teeth were labeled as “survived.” Follow-up was done at regular intervals after 5, 7, and 10 years, respectively. At the end of 10 years, the number of teeth survived was 26. The teeth restored with composite were 14. The teeth restored with GIC were 4. The teeth restored with silver amalgam were 8. Results: At the end of the observation time period (10 years), 13 teeth had to be extracted at the end of 6 years and 19 restorations were repaired or replaced at 5, 7, and 9 years. Conclusion: Within the limitations of this study, the amount of remaining tooth structure and types of restorative material have a significant association with the longevity of endodontically treated molars without crown coverage. ETTs evaluated after 10 years showed positive survival and success in long time period. Various parameters were significantly seen to influence the outcome and thereby survival of teeth in the arch when no crowns were placed on ETTs.