Crown Form Research Articles

Crown forms and gingival phenotypes: Insights from a diverse Asian population

ObjectiveThis study aimed to classify the crowns of maxillary central incisors into distinct categories and to examine the associations between these crown forms and morphometric characteristics in an ethnically diverse Asian population. This is significant for the treatment planning and management of cases, especially for the anterior teeth, from the restorative and aesthetic points of view. Method and MaterialsClinical measurements and photographic data were collected from 160 participants, comprising students, staff, and patients of the Faculty of Dentistry, Universiti Kebangsaan Malaysia. The crown length, crown width, contact surface, papilla height, papilla fill, keratinized mucosa width, and gingival tissue thickness were measured. Cluster analyses were performed to identify the different crown form categories and corresponding characteristics. ResultsThe mean crown width measured 7.093 ± 0.637 mm, while the mean crown length was 10.209 ± 0.966 mm. Three crown-form clusters were identified: triangular (50 %), square/tapered (23.1 %), and square (26.9 %) shapes. The triangular cluster had a significantly higher mean papilla height (4.64 mm ± 0.818) and the highest incidence of incomplete papilla fill (17.5 %). The chi-squared test showed a significant difference in crown forms between the different ethnicities, χ2 (2, 160) = 0.033. ConclusionWithin this diverse Asian population, the crown form demonstrates three clusters: triangular, square/tapered, and square, characterized by a notably small average crown width and crown length. Most participants predominantly exhibited triangular crown forms with reduced crown width, crown length, and crown width/ crown length ratio. Furthermore, noticeable variations in crown forms and their morphometric attributes were observed among the three ethnic groups: Malays, Chinese, and Indians.

Convective flow generated in viscous liquid by isothermal and isoconcentration distribution in crown enclosure with novel aspects of inclined magnetic field

ABSTRACT Combined buoyancy shifts from temperature and concentricity gradients create double-diffusive convection. Complex Crown form enclosure with heat and mass source brings originality and practicality by enhancing use in a broad variety of technical, industrial, and geophysical operations. Current artifact is to explore thermosolutal diffusion in buoyantly driven flowing of viscid liquid contained in a crown enclosure with the installation of a uniformly heated and soluted circular cylinder. Novel physical characteristics of inclining magnetic field are introduced, and distributions affected by cylinder radius change are compared. Dimensionless PDEs are solved numerically using finite elements. Grid independence test ensures simulation mesh level. Hybrid meshing with triangular and rectangular components discretizes domain. Linear interpolating polynomials approximate pressure, whereas quadratic polynomials approach velocity, temperature, and concentricity. PARDISO solves a non-linear system of equations efficiently. Average Nusselt and Sherwood numbers are estimated by comparing relevant parameters to cylinder radius change. Heat transference rate rises to 40% and mass transport upsurges to 60% when radius of cylinder is increased from 0.1 to 0.2. Hartmann number tends to affect a decline in Nusselt and Sherwood quantities. Reduction in thermal and solutal boundary layers near surface of the cylinder is observed against the improve in radius of cylinder.

Experimental and numerical study of the post-impact behavior of a water droplet impacting on a hydrophilic surface with a cylindrical cavity

In this study, we couple a laboratory experiment with numerical simulations to investigate the post-impact behavior of a water droplet impacting a hydrophilic surface with a cylindrical cavity. In the experiment, we observe that either an increase in the depth of the cavity or a decrease in its diameter will promote crown formation, and the crown will be higher but narrower on a deeper or narrower cavity. Moreover, a higher impact speed leads to a larger crown. The numerical simulations of post-impact droplet behavior are in good agreement with the experimental results. More importantly, they shed light on the physics underlying the formation and development of the crown by computing the forces induced on the bottom, vertical wall, and surrounding wall of the cavity as the droplet impacts there. The simulations suggest that the cavity size and the impact speed play significant roles in determining the force profiles and thus whether a crown forms and, if so, how large it is. On the basis of the experimental and numerical results, we construct regime diagrams for the crown formation by considering the critical values of cavity size and impact speed.

The gingival phenotypes and related clinical periodontal parameters in a cohort of Pakistani young adults

ObjectiveTo evaluate the gingival phenotypes of healthy young adult Pakistanis attending a dental institution. MethodsA cross-sectional study of gingival phenotype, probing depth (PD), papilla height (PH), gingival width (GW), gingival thickness (GT), crown width (CW) and crown length (CL) of maxillary central incisors was conducted in 510 healthy, Pakistani young adults, aged 20–35 years, attending a regional dental hospital in Pakistan. The K-means clustering technique was employed to delineate clusters based on the characteristics of the periodontal phenotypes. The resultant data was compared with the available international findings. ResultsThree quarters (76 %) of the 510 patients examined exhibited a thick gingival phenotype, and the remainder a thin phenotype. The K-means clustering deployed the individual into three different clusters 1, 2 and 3, with varying ratios of PD, GW, CW/CL, with significant variations across the three clusters (p < 0.05). Our data where a vast majority of the cohort exhibited a thick gingival phenotype is comparable to most of the populations sampled in other regions of the world. ConclusionTaken together the current data, a first for a Pakistani population, indicate that healthy, young adult Pakistanis had differing gingival phenotypes and crown forms, with the thick gingival phenotype predominating. These results are similar to reports from most other regions of the world. However, a larger study with a broader swathe of the Pakistani population is required to derive country specific data on the subject.

Tree pruning improves tree form but not understory plant production in mixed stands of Sitka spruce and western hemlock, USA

Abstract Precommercial thinning and tree pruning are frequently used together to improve timber quality and wildlife habitat in even-aged Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla) stands. Thinning enhances crop tree growth and understory plant production; however, the benefits and drawbacks of tree pruning have received less attention. Tree pruning was investigated in two long-term experiments on the Tongass National Forest, Alaska, USA. Experiment 1 tracked four uniformly thinned sites for ~30 years that received 2.4, 3.6, and 5.2 m lift, and no pruning treatments. Experiment 2 tracked 11 sites for 16 years that received thinning/no pruning, thinning plus pruning (25% of trees), thinning plus pruning (50% of trees), and no thinning/no pruning treatments. We investigated (i) how pruning lift height affects tree form and understory production and (ii) how pruning density affects canopy closure and understory production. In Experiment 1, pruning reduced butt log taper and did not adversely affect diameter or height in either species. Pruning lift was visible in height-to-live crown measurements. Crown recession occurred first in low lift treatments and later in all treatments until crown form was similar after 28–31 years. Epicormic branching rates in Sitka spruce peaked 6–9 years after treatment before falling sharply. Deer forage declined through time and did not differ between lift treatments. In Experiment 2, canopy closure was lower shortly after thinning and pruning, but did not differ from the control after 16 years. Epicormic branching rates were greater shortly after thinning and pruning but did not differ from the control after 16 years. Deer forage declined with canopy closure and thinned and pruned treatments exhibited greater forage than the control. We conclude that pruning can improve log quality for timber applications but does not enhance understory plant biomass and deer forage over thinning treatment alone.

Morphological Crown Attributes Contributing to Differential Height and Diameter Growth among Families in a Coastal Douglas-Fir Progeny Test: Crown Structural Evidence for Crop Ideotypes

Theoretical tree crop ideotypes have long and narrow live crowns with a high total leaf area. This crown form allows more efficient exploitation of site resources, in part by physically occupying less growing space per unit leaf area and by packing a greater number of trees into a given area. Genetic selection for crop ideotypes has been proposed as a strategy for maximizing productivity per unit area in stands managed under intensive silviculture. The primary objective of this study was to test the relationship between the relative growth performance of different families in a Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) progeny test and morphological crown attributes that conform to a theoretical crop ideotype. The overarching goal was to identify attributes conferring superior height and diameter growth on families and to facilitate the incorporation of these attributes and associated growth mechanisms into hybrid growth models for intensively managed plantations. Crown structural attributes were measured on destructively sampled trees and averaged for the entire crown and each third of live crown length among families. Multivariate analysis revealed that crown attributes averaged over the entire crown performed best for identifying families with different height and diameter growth, followed successively by the bottom, middle, and top crown third. Trees with relatively short branch lengths and steep branch angles tended to have higher total leaf area per unit crown length (TLACL), and this structural attribute showed a strong positive correlation with cumulative diameter growth. The ratio of crown width to crown length (CWL) was moderately and negatively correlated with cumulative height growth. The families displaying the most rapid diameter growth in this progeny test conformed to a theoretical crop ideotype, while those with the most rapid height growth displayed crown attributes with a less obvious relationship to the crop ideotype concept. TLACL implied one possible mechanism driving genetic gain in Douglas-fir families, given its high heritability and strongly positive correlation with growth performance. Incorporating TLACL as an explanatory variable in diameter growth models could at least partly represent different genetic levels. TLACL is less strongly correlated with height growth rate, so incorporating CWL may better represent genetic effects on height growth models.

Parameters of apple tree crowns depending on the crown shape and pruning time

The apple tree is a leading fruit crop in Ukraine in terms of production volumes and planting areas and is a valuable food product with a high content of vitamins. In new modern plantings, fruit producers prefer intensive cultivation technologies that ensure the maximum amount of high-quality fruit yield per unit area. The main criterion for solving this problem is the design of plantings: a narrow-row scheme for planting trees and a low-volume crown shape. The purpose of the study was to establish the influence of the pruning period of different types of crown formations on the growth and productivity of apple trees of two varieties: Fuji and Honey Crisp. The study was conducted in the conditions of the central Forest-Steppe of Ukraine (Uman National University of Horticulture). The scheme of planting was 4x1 m, M.9 rootstock, chernozem sod-podzolic soil, drip irrigation. Field, statistical, and computational-analytical methods were used in the course of the study. It was identified that the growth pattern of the examined varieties differed substantially, and crown volume, projection area, and development of the feeding area prevailed in Honey Crisp trees. However, in terms of productivity, the plantings of the Fuji variety substantially exceeded the values of the Honey Crisp variety. Forming a ballerina crown with the removal of overgrown wood in a 25 cm zone on the central trunk above the lower tier of semi-cellular branches provided an increase in the growth activity of the examined trees by 3-5%. A substantial decrease in the values of crown parameters was provided by the formation of the French axis crown – there was a decrease in the crown diameter by 44%, the crown volume – by 67%, and the crown projection area and the development of the feeding area – by 69%. Performing additional summer pruning of trees also helped to reduce growth activity by 6-11%. However, the specific productivity of plantings doubled in plantings with the formation of the French axis and by 45-50% with the introduction of double pruning of trees. It is recommended that agricultural producers investigate the terms of pruning low-volume crown forms, considering varietal characteristics, to create compacted apple stands and increase the intensification of production

Effect of margin design changes on stress distribution in zirconia-based full-crown restorations: A three-dimensional finite element analysis

Aim: The aim of this study was to evaluate the effect of margin design changes on the stress distribution in zirconia-based full-crown restorations using three-dimensional finite element analysis. Methodology: For use in the design of full-crown restorations, tooth number 16 was prepared in chamfer step type on a maxillary tooth jaw model (AG-3: Tipodont, Frasaco, Germany). The prepared tooth was scanned using a desktop scanner, and a three-dimensional finite element analysis model was obtained. Zirconia frameworks are divided into three groups according to the margin design: uniform thickness hood type (Model A), ¾ partial crown form (Model B), and a lingual-band type (Model C). The crown form was completed using feldspathic porcelain as the superstructure material. To determine the stress distribution of the margin design on the restoration, the maximum principal stress (MPa) values under a 600 N vertical load were investigated. Results: The maximum stress on the zirconia framework was observed in Model A (82.90 MPa), and the maximum stress on the tooth was observed in Model B (49.34 MPa). The maximum stress on the feldspathic porcelain was highest in Model A (21.860 MPa), and the minimum stress on the tooth occurred in Model B (13.33 MPa). In the zirconia framework, the lowest stress was 11.54 MPa (Model B). Conclusion: The framework design was shown to affect the force generated on the restoration and transmitted to the tooth. The results of the present study will help dentists determine the ideal infrastructure design for zirconia-based restorations. Lingual band designs were found to be successful. How to cite this article: Güntekin N, Mohammadi R, Tunçdemir AR. Effect of margin design changes on stress distribution in zirconia-based full-crown restorations: A three-dimensional finite element analysis. Int Dent Res 2022;12(Suppl.1):10-5. https://doi.org/10.5577/intdentres.439 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Influence of interdental embrasures on interdental papilla

Background: There is growing attention on anterior esthetics by both dentists and patients, which emphasizes the need for conduct of study encompassing the anatomical features of an embrasure and correlating with papilla fill. Hence the present study has been designed to meet these parameters, including food lodgement.&#x0D; Aim: To assess the influence of anatomical and morphological characteristics of interdental embrasures on interdental papilla and food lodgement.&#x0D; Objectives: were set as the following:&#x0D; 1.Correlation of Modified Papilla Index Score (PIS) with interdental anatomical measurements as follows:&#x0D; a. Distance between Contact Point and Bone Crest (CP-BC). b. Interdental Distance (IDD).c. Embrasure Space Area (EA).d. Crown Form (CF).e. Papilla Length (PL).&#x0D; 2.To determine the optimal dimensions of interdental embrasure between maxillary incisors so as to be completely filled by normal healthy interdental papilla.&#x0D; 3.To correlate occurrence of food lodgement with Modified Papilla Index Score (PIS) and Embrasure Space Area (EA).&#x0D; Materials and methods : 532 patients aged 18-58 years who had fully erupted permanent dentition and healthy gingiva with probing depth ≤ 3mm were included into the study. Quantitative analysis of interdental papillae were done using clinical parameters along with radiographic examination.&#x0D; Results : The clinical and radiographic assessment of 1312 interdental papillae revealed that the interdental anatomical factors viz (which are) CP-BC distance, IDD, EA, CF and PL significantly influenced the degree of papilla fill. The study also highlighted the possible occurrence of food lodgment in patients with open embrasures.&#x0D; Conclusion : Embrasure anatomical parameters and papillary heightvary widely among individuals. Interdental papillary deficiency is a relative phenomenon since it is an outcome of net influence of all the other parameters.

Human disturbance influences occupancy of Altai wapiti in Mongolia

This study was conducted to investigate effects of thinning on the tree growth and stand characteristics in Pinus sylvestris plantation forests, northern Mongolia. Three study sites were located in the Tujiin nars area, in 18- to 20-year-old plantation forests that were thinned in 2016 and 2017, respectively. In each site, three plots in thinned and an unthinned (control) plot were established to examine changes in growth and stand characteristics. Thinning induced an increase in diameter increment and it was strongly correlated with annual precipitation and year of planting at all sites. The effects of thinning on height growth were insignificant. Crown morphology differed significantly between thinned and unthinned stands; thinning increased crown diameter and crown projection area but mean crown length and crown form index were higher in unthinned stands.

Short-term effects of thinning on the growth and stand characteristics of Scots pine (Pinus sylvestris L.) plantations in northern Mongolia

This study was conducted to investigate effects of thinning on the tree growth and stand characteristics in Pinus sylvestris plantation forests, northern Mongolia. Three study sites were located in the Tujiin nars area, in 18- to 20-year-old plantation forests that were thinned in 2016 and 2017, respectively. In each site, three plots in thinned and an unthinned (control) plot were established to examine changes in growth and stand characteristics. Thinning induced an increase in diameter increment and it was strongly correlated with annual precipitation and year of planting at all sites. The effects of thinning on height growth were insignificant. Crown morphology differed significantly between thinned and unthinned stands; thinning increased crown diameter and crown projection area but mean crown length and crown form index were higher in unthinned stands.

Горобина домашня (Sorbus domestica L.): біоекологічні особливості нових форм і біохімічні показники плодів для перспективних напрямів у селекції на адаптивність і якість

It is the formation of a new and replenishment of the existing breeding and genetic bank and selection of the biotypes from the natural and semi-natural ecological systems, local, inland and foreign cultivars etc. that is actual in the implementation of the breeding programmers for the creation of new genotypes of minor crops the biological potential of which meets the modern requirements of horticulture. The analysis of the theoretical material has shown that the representatives of the species Sorbus domestica L. have the greatest importance for breeding which possesses a rather big areal in Ukraine (the Transcarpathia, locally under the conditions of the Lisosteppe), in the Baltic counties (Chernogoria, Serbia), Haly, France, Great Britain, Cheque, Spain, Switzerland, Austria, Germany, Algeria, Tunissia and so on. In the natural conditions of Crimea and the Transcarpathia service-tree mountain ash grows as single trees mainly in the under-wood of beech-hornbeam, oak and hornbeam - oak forest. The analysis of the literary data has shown that outstanding scientists obtained a considerable amount of S. domestica in particular, 8 varieties were created. In Crimea the researchers of the Nikitsky Botanical Garden selected 6 forms from local samples the investigators of the M. M. Gryshko National Botanical Garden (NBG) of the National Academy of Sciences of Ukraine did one form 4 cultivars lected in – in Serbia, 3 – in Italy, 1 – in Great Britain. The M.M. Hryshko NBG experts state that in our country the service-tree mountain ash plants flowering stage falls on the end of the third decade of April or the beginning of the first one of May and in some years on the second decade of April on the average this stage lasts 10-14 days. In Ukraine the S. domestica fruits technical and complete ripeness begins in September-October. The every year fruit-bearing of the most of the service-tree mountain ash plants begins in the eight-twelfth years of life and the yield of a forty years tree may be 100-250 kg of fruits (maximum up to 1500 kg). Under the field conditions of the IH NAAS stationary among the numerous seedlings five S. domestica forms (F 01/17-G, F 04/17-G, F 12/17-G, F 19/17-G and F 22/17-G)were selected which are characterized with the increased hardiness concerning unfavourable environmental factors, green shades of leaves, distinguish themselves for the ornamentality of the crown form. The nitrogenous fertilizers are recommended to be used for the service tree mountain ash plants (including two-three years ones) only in spring (in April-May) and summer (July). The autumn top-dressing with the mentioned fertilizers should not be applied because it causes the vegetation period prolonging and the plants winter-hardiness decrease. In the framework of the scientific cooperation between the Institute of Horticulture and M.M. Hryshko NBG the S. domestica forms were explored on the territory of the above mentioned garden berries were selected and estimated as regards their morphological traits and biochemical properties for the further breeding on adaptability and quality.

The morphobiological specificities of the growth and development of promising hawthorn seedlings with different crown shapes in the conditions of the Central Black Earth Region

In the literature there is very little information about fruiting, growth activity of various hawthorn species. Therefore, a comprehensive study of hawthorns is necessary in order to improve the health and living conditions in cities, as well as to obtain the highest quality harvest of fruits with valuable traits. The article presents data on the development of phases of vegetation of elite hawthorn seedlings using natural, improved vase-like and sparse-tiered crown forms in the Central Black Earth Region. It was found that the greatest annual growth of shoots was observed in the elite seedling Michurinsky Dessertniy with an improved vase-like crown shape. The largest fruits were obtained from an improved vase-like crown shape of hawthorn trees, (Karamelka, 3.7 g; Tambovskiy Volk, 3.4 g).

Responses of Visual Forms to Neighboring Competition: A Structural Equation Model for Cotinus coggygria var. cinerea Engl.

Background: The visual forms of individual trees in peri-urban forests are driven by a complex array of simultaneous cause-and-effect relationships. Materials and Methods: Structural Equation Modeling (SEM), as a specialized analytical technique, was used to model and understand the complex interactions. It was applied to find out responses of visual forms to neighboring competition in a peri-urban forest dominated by Cotinus coggygria var. cinerea Engl. in Beijing, China. Research Highlights: Light interception and space extrusion have substantial effects on visual forms, expressed as crown forms and foliage forms. The structural model in SEM tested hypothetical correlations among latent variables, namely neighboring competition, crown forms, and foliage forms. Results: The fitted model suggested a direct negative effect of neighboring competition on crown forms and an insignificant negative direct effect on foliage forms. Moreover, an indirect positive effect on foliage forms mediated by crown forms was revealed. Conclusions: The fitted SEM and associated findings should facilitate peri-urban forest landscape management by providing insight into causal mechanisms of visual forms of individual trees and thereby assisting in the visual quality promotion.

Phenotypic Variability and Differences in the Drought Response of Norway Spruce Pendula and Pyramidalis Half-Sib Families

In a changing climate, forest managers need to select productive and climate-change-resilient tree species and provenances. Therefore, assessing the growth response of provenances growing in field trials to climate provides useful information for identifying the more appropriate provenance or variety. To determine the genetic gain through selection of the most productive and resilient families and to decipher the role of crown forms of Norway spruces (Picea abies (L.) Karst.), we used 24 families with a classical crown (pyramidalis) and 24 with a narrow crown (pendula) from eight provenances, growing in a 25-year-old comparative trial. The annual wood characteristics (ring width and early- and latewood), the wood resistance (expressed by latewood proportion (LWP)), and the growth response to climate of the two spruce crown forms were investigated. No significant differences between the two spruce forms were found regarding the ring width characteristics. However, three pendula families of Stâna de Vale I provenance exhibited the highest LWP and could be included in a future selection strategy, the respective trait having also high heritability. Radial growth was positively and significantly correlated with previous September and current July precipitation and negatively with current June temperature. Both spruce forms showed good recovery capacity after a drought event.

Upper canopy tree crown architecture and its implications for shade in cocoa agroforestry systems in the Western Region of Ghana

Several studies have been conducted on shaded cocoa systems, but few of these have examined species-specific crown architecture of upper canopy trees and its influence on shade provision in cocoa agroforestry systems. In view of the fact that cocoa agroforestry is a recommended practice to drive cocoa production onto a climate-smart pathway, and given the role of upper canopy trees in the moderation of shade and light to the cocoa system, there is the need to understand the dynamics of upper canopy crown as well as dendrometric parameters and how these parameters influence shade provision for the cocoa system. Employing a replicated transect method, quantitative data on upper canopy trees in cocoa agroforestry systems were collected from twelve (12) 1 ha plots established on a 5 km long transect at the Bonsu Nkwanta cocoa growing district in the Western Region of Ghana. Given that there was no existing information on various crown forms of upper canopy trees in cocoa systems in Ghana, the crown forms generated by (Frank, 2010) were adopted for this study. These were “spreading to cylindrical”, “elongate to rounded to oval”, “upswept and vase shaped”, “conical to pyramidal” and “spade shaped” crown forms. One hundred and sixty (160) upper canopy trees comprising of 44 species, which were distributed in 21 families were recorded in the cocoa agroforestry systems surveyed in the study area. Newbouldia laevis was observed to be the most abundant species recorded in the sampled farms. The results showed that crown and dendrometric characteristics of the upper canopy trees did not differ in cocoa agroforestry systems of different ages. Also, the highest values of crown volume, crown area and shade area were recorded by the “spreading to cylindrical” crown forms followed by the “elongate” crown form, respectively. Furthermore, the study showed that crown area, crown volume, crown diameter, tree DBH and crown height were the parameters that strongly affected the ability of a particular crown form of a tree to provide higher shade. Based on the results, we conclude that in selecting upper canopy trees for the provision of shade in cocoa agroforestry systems, trees with “spreading to cylindrical” and “elongate” crown forms are the most suitable crown forms to incorporate in cocoa agroforestry systems. However, these constituted the least crown forms in the cocoa systems studied. The study provides a useful guide to the selection and management of upper canopy tree species for the provision of shade in cocoa agroforestry systems, and holds further applications for the provision of decision support for the promotion of climate – smart cocoa agroforestry in Ghana and the West African cocoa belt.

Correlation analysis of periodontal tissue dimensions in the esthetic zone using a non-invasive digital method.

PurposeDirect intraoral scanning and superimposing methods have recently been applied to measure the dimensions of periodontal tissues. The aim of this study was to analyze various correlations between labial gingival thickness and underlying alveolar bone thickness, as well as clinical parameters among 3 tooth types (central incisors, lateral incisors, and canines) using a digital method.MethodsIn 20 periodontally healthy subjects, cone-beam computed tomography images and intraoral scanned files were obtained. Measurements of labial alveolar bone and gingival thickness at the central incisors, lateral incisors, and canines were performed at points 0–5 mm from the alveolar crest on the superimposed images. Clinical parameters including the crown width/crown length ratio, keratinized gingival width, gingival scallop, and transparency of the periodontal probe through the gingival sulcus were examined.ResultsGingival thickness at the alveolar crest level was positively correlated with the thickness of the alveolar bone plate (P<0.05). The central incisors revealed a strong correlation between labial alveolar bone thickness at 1 and 2 mm, respectively, inferior to the alveolar crest and the thickness of the gingiva at the alveolar crest line (G0), whereas G0 and labial bone thickness at every level were positively correlated in the lateral incisors and canines. No significant correlations were found between clinical parameters and hard or soft tissue thickness.ConclusionsGingival thickness at the alveolar crest level revealed a positive correlation with labial alveolar bone thickness, although this correlation at identical depth levels was not significant. Gingival thickness, at or under the alveolar crest level, was not associated with the clinical parameters of the gingival features, such as the crown form, gingival scallop, or keratinized gingival width.

Фотосинтетическая продуктивность листьев вишни и черешни в связи с формами кроны

The scientific article presents the results of research work on the study of varietal characteristics of sour cherry and sweet cherry and methods for artificial formation of tree crowns at the level of photosynthetic activity of leaves with the orientation of growing trees by their intensive technology. Zoned cherry varieties Shubinka, Podbelskaya and Shpanka chernaya, sweet cherry Bakhor, Revershon and Drogana jyoltaya grown on a weak vegetatively propagated rootstock BBA-1 and BCL-2 (Krymskiy-5) were used as the object of the study. As a result of the conducted research, it was found that the optimal crown system for varieties of sour cherry and sweet cherry is a five skeletal wall. The formation of the crown in these forms contributes to a decrease in the volume of the crown by an average of 25%, at which the net productivity of leaf photosynthesis in comparison with the usual formation of the crown — freely growing and sparse-tiered shape, reaches 34.73 g/m2 per day. With the formation of bushy crown forms in cherries and sweet cherries, the level of leaf formation improves and the chlorophyll content in the leaves increases to 13.42 mg /g of fresh weight of leaves.

Terrestrial laser scanning reveals convergence of tree architecture with increasingly dominant crown canopy position

AbstractTo fulfil their growth and reproductive functions, trees develop a three‐dimensional structure that is subject to both internal and external constraints. This is reflected by the unique architecture of each individual at a given time. Addressing the crown dimensions and topological structure of large tropical trees is challenging considering their complexity, size and longevity. Terrestrial laser scanning (TLS) technology offers a new opportunity for characterising and comparing these properties across a large number of individuals and species.In the present study, we specifically developed topology and geometry metrics of crown architecture from TLS data and investigated how they correlated with metrics of tree and crown form, crown position and shade tolerance.Fifty‐nine trees belonging to 14 coexisting canopy species in semideciduous forests of Cameroon were scanned with TLS and reconstructed using quantitative structural models (QSMs). The species belonged to different shade‐tolerance groups and were sampled in different crown positions. Crown‐form metrics and branch topology metrics were quantified from the TLS data, and principal component analysis (PCA) was used to study how the 59 sampled trees were distributed along axes of architectural diversity. Allometric scaling parameters derived from West Brown and Enquist (WBE) metabolic theory were also quantified from the QSMs, and their correlations with the PCA axes were evaluated.The results revealed that the branch topology and crown‐form metrics were not correlated since similar topologies could lead to contrasting crown forms. Crown form, but not branch topology, changed with tree shade tolerance, while convergence in tree topology and towards expected WBE parameters was observed for all trees reaching dominant crown positions independent of species shade tolerance.This convergence is interpreted as resulting from a liberation effect of canopy trees from side‐shading constraints, leading to crown development processes through sequential reiteration.A freePlain Language Summarycan be found within the Supporting Information of this article.

Influence of Different Thinning Treatments on Stand Resistance to Snow and Wind in Loblolly Pine (Pinus taeda L.) Coastal Plantations of Northern Iran

Loblolly pine (Pinus taeda L.) is one of the main exotic conifer species that has been widely planted for the past fifty years for timber production in the coastal areas of northern Iran. Heavy snowfall and strong winds can cause much damage to these forests over a short time span of only a few years. This study was conducted to estimate snow and wind damage and analyze the role of stand thinning in their resistance to snow and wind. Amount and type of snow and wind damage were examined through systematic (80 m × 80 m) sample plots (each plot area of 625 m2) in nine different stands (2–10 plots in each stand) in terms of age, structure, and silviculture history in three replications for each stand in April and May 2020. Results showed that the amount of snow and wind damage had a wide range from 1.3% to 30.7%. Snow damage was more than three times that of wind. Snow and wind damage in the young stands were significantly more serious (p &lt; 0.01) than in the middle-aged and old stands, and damage was significantly higher (p &lt; 0.01) in the unthinned stands than in the thinned ones. Slenderness coefficient (Height/Diameter ratio, HD ratio) of trees resulted to be a good indicator in young and middle-aged stands, while crown form indices (relative crown length and relative crown width) were acceptable indicators in old stands for risk of snow and wind damage. Our results showed that the normal thinning (15% of basal area) decreased snow and wind damage in all the stands, while the heavy thinning (35% of basal area) reduced the snow damage, but it increased the wind one. It is possible to recommend high intensity thinning in young stands, normal thinning in middle-aged stands, and light thinning (15% of basal area) in old ones.