Complexities in endodontics: A case series

There are cases in the endodontic treatment which are a real challenge. There are teeth with different anatomies of the root canals of different teeth and their treatment. There are most of the cases which are sevely carious and has lost more than 50% of the tooth structure. Patients usually lose their teeth because these problems. The aim of this study is to investigate several cases with different root canal anatomies like in open apex with blunderbuss canals in maxillary central incisors or mandibular premolar and molars with severly decayed crown tooth structures and their management. one case with severly decayed lower mandibular premolar i.e 45, one case of maxillary first molar with severly decayed crown structure i.e 16, a case of severly decayed mandibular first molar i.e 36, Three Cases of maxillary central incisors with immature open apex and blunderbuss canals w.r.t 21. Results are observed after several years. In performing a root canal treatment on such teeth, one should appreciate the complexity of the root canal system, canal obliteration and configuration, and the potential for regenerating the original anatomy of the tooth either Endodontic or Post Endodontic. Knowledge of the phenomenon of the complexity of the root canal system, canal obliteration and configuration, and the potential for regenerating tooth anatomies with the help of rebond fibres, MTA and Composite restorations, this will improve the medical practice of the general dental practitioner.

Yield and crown structure characteristics in a red oak (Quercus rubra L.) stand: Case study

The paper provides the results of a detailed analysis of timber volume and several important crown variables of red oak (Quercus rubra L.) based on an experimental plot in eastern Hungary. At the age 32 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I was considered as 100%, the volume of the mean tree of class II was 59%, and the mean tree of class III was only 36%. It appeared that there was a significant correlation between crown indices and yield. For this reason, diameter at breast height showed a positive linear correlation with crown diameter (R2= 0.6211). Additionally, there was also positive linear relationship between crown diameter and volume (R2= 0.6908). The variation of crown indices is height even within the same stand and indicates the importance of following a selective thinning operation method.

Virtual pruning of 3D trees as a tool for managing shading effects in agroforestry systems

Light is a limiting resource for crops within integrated land use systems especially those including woody perennials. The amount of available light at ground level can be modified by artificially pruning the overstory. Aiming to increase the understanding of light management strategies, we simulated the pruning of wild cherry trees and compared the shading effects of the resulting tree structures over a complete growing season, with fine spatiotemporal resolution. Original 3D-tree structures were retrieved employing terrestrial laser scanning and quantitative structure models, and subjected to two pruning treatments at low and high intensities. By using the ‘shadow model’, the analogous tree structures created diverse shaded scenarios varying in size and intensity of insolation reduction. Conventional pruning treatments reduced the crown structure to the uppermost portion of the tree bole, reducing the shading effects, and thus, shrinking the shaded area on the ground by up to 38%, together with the shading intensity. As an alternative, the selective removal of branches reduced the shading effects, while keeping a more similar spatial distribution compared to the unpruned tree. Hence, the virtual pruning of tree structures can support designing and selecting adequate tending operations for the management of light distribution in agroforestry systems. The evidence assembled in this study is highly relevant for agroecosystems and can be strategically used for maintaining, planning and designing integrated tree-crop agricultural systems.

Diversity of the hybrid forms between Siberian stone pine and Siberian dwarf pine

Siberian stone pine (Pinus sibirica) and Siberian dwarf pine (P. pumila) are Russian five-needle pines withdifferent life forms, namely upright tree and prostrate tree, respectively. Hybridization of the species was considered in thepaper from the point of view of the habitus of their natural hybrids. In early studies, it was always noted that the hybridswere intermediate in comparison with the parental species. Crown structure in hybrids are largely determined by twomain factors. These are deflection of the tree stem from the vertical axis and the selectivity of apical dominance. Hybridsgrowing in open places under full lighting conditions are characterized by strictly intermediate growth form. In a forestwhere there is no enough light, hybrid reaches for sun but gradually deviates to the side, which ultimately leads to a branchbreak or even the roots of the entire tree being upturned from the soil. In the mountains, hybrids can form uniform trunkbranches, forming a cup-shaped crown, similar to how it happens in Siberian dwarf pine. Thus, the previously notedintermediate morphology of hybrids represents a series of forms, from almost vertical multi-stemmed trees to pumila-likeones with a cup-shaped crown.

The non-brain anterior nerve center and tentacle crown structure of Owenia borealis (Annelida, Oweniidae): the evolution of the nervous system and tentacles in Bilateria

The Oweniidae are marine annelids with many unusual features of organ system, development, morphology, and ultrastructure. Together with magelionds, oweniids have been placed within the Palaeoannelida, a sister group to all remaining annelids. The study of this group may increase our understanding of the early evolution of annelids (including their radiation and diversification) and of the morphology of the last common bilaterian ancestor. In the current research, scanning electron microscopy revealed that the tentacle apparatus consists of 10 branched arms. The tentacles are covered by monociliary cells that form a ciliar groove that extends along the oral side of the arm base. Light, confocal, and transmission electron microscopy revealed that head region contains two circular intraepidermal nerves (outer and inner) that give rise to the neurites of each tentacle, i.e., intertentacular neurites are absent. Each tentacle contains a coelomic cavity with a network of blood capillaries. Monociliar myoepithelial cells of the tentacle coelomic cavity form both the longitudinal and the circular muscles. The structure of this myoepithelium is intermediate between simple and pseudo-stratified myepithelium. Overall, tentacles lack prominent zonality, i.e., co-localization of ciliary zones, neurite bundles, and muscles. This organization, which indicates a non-specialized tentacle crown in O. borealis and other oweniids with tentacles, is probably ancestral for annelids and for all Bilateria. The outer circular nerve of O. borealis is a dorsal medullary commissure that apparently functions as an anterior nerve center and is organized at the ultrastructural level as a stratified neuroepithelium. Given the hypothesis that the anterior nerve center of the last bilateral ancestor might be a diffuse neural plexus network, these results suggest that the ultra anatomy of that plexus brain might be a stratified neuroepithelium. Alternatively, the results could reflect the simplification of structure of the anterior nerve center in some bilaterian lineages.

Crown Structure Explains the Discrepancy in Leaf Phenology Metrics Derived from Ground- and UAV-Based Observations in a Japanese Cool Temperate Deciduous Forest

Unmanned aerial vehicles (UAV) provide a new platform for monitoring crown-level leaf phenology due to the ability to cover a vast area while offering branch-level image resolution. However, below-crown vegetation, e.g., understory vegetation, subcanopy trees, and the branches of neighboring trees, along with the multi-layered structure of the target crown may significantly reduce the accuracy of UAV-based estimates of crown leaf phenology. To test this hypothesis, we compared UAV-derived crown leaf phenology results against those based on ground observations at the individual tree scale for 19 deciduous broad-leaved species (55 individuals in total) characterized by different crown structures. The mean crown-level green chromatic coordinate derived from UAV images poorly explained inter- and intra-species variations in spring leaf phenology, most probably due to the consistently early leaf emergence in the below-crown vegetation. The start dates for leaf expansion and end dates for leaf falling could be estimated with an accuracy of <1-week when the influence of below-crown vegetation was removed from the UAV images through visual interpretation. However, a large discrepancy between the phenological metrics derived from UAV images and ground observations was still found for the end date of leaf expansion (EOE) and start date of leaf falling (SOF). Bayesian modeling revealed that the discrepancy for EOE increased as crown length and volume increased. The crown structure was not found to contribute to the discrepancy in SOF value. Our study provides evidence that crown structure is a pivotal factor to consider when using UAV photography to reliably estimate crown leaf phenology at the individual tree-scale.

The Potential Influence of Tree Crown Structure on the Ginkgo Harvest

Ginkgo biloba L. has significant health benefits and considerable economic value, but harvesting the fruit is highly labor-intensive. Mechanical vibration harvesting has been shown effective in harvesting various fruit types. In the study of vibration harvesting, the research on the vibration characteristics of fruit trees focuses on the natural frequency (resonance frequency), model, and damping coefficient, which are the main factors affecting the vibration characteristics of trees. But field harvesting experiments have shown that the tree structure may have an impact on the vibration characteristics of the fruit tree and the efficiency of mechanical harvesting. In addition, the research on the damping coefficient of fruit trees is mainly low-frequency damping, and the relevant results cannot be applied to the actual vibration harvesting frequency range. Applying a natural frequency with low damping coefficient to excite a tree can reduce additional energy dissipation. This study explored the influence of ginkgo crown structure on the vibration characteristics and the law of damping changes with frequency. After counting 273 ginkgo trees, two typical ginkgo crown structures, monopodial branching and sympodial branching, were selected to be analyzed for vibration spectrum and damping coefficient. The vibration models for different crown-shaped ginkgo trees were simulated to analyze the vibration state at different frequencies. For sympodial branching ginkgo trees, the consistency of natural frequencies at different branches was better than monopodial branching ginkgo trees. The finite element model analysis shows that monopodial branching ginkgo trees have mainly partial vibrations at different branches when vibrating at high frequencies. The high-frequency vibrations in sympodial branching reflect the better overall vibration of the canopy. The damping coefficients for the two crown types decreased with the increase in frequency. The monopodial branching damping coefficient was 0.0148–0.0298, and the sympodial branching damping coefficient was slightly smaller at 0.0139–0.0248. Based on the test results, the sympodial branching ginkgo tree has better vibration characteristics. The results indicate that controlling the crown structure of fruit trees to be sympodial branching by pruning may help improve the overall vibration characteristics of fruit trees.

Tree growth as affected by stem and crown structure

Key message Prediction of tree growth based on size or mass as proposed by the Metabolic Scaling Theory is an over-simplification and can be significantly improved by consideration of stem and crown morphology. Tree growth and metabolic scaling theory, as well as corresponding growth equations, use tree volume or mass as predictors for growth. However, this may be an over-simplification, as the future growth of a tree may, in addition to volume or mass, also depend on its past development and aspects of the current inner structure and outer morphology. The objective of this evaluation was to analyse the effect of selected structural and morphological tree characteristics on the growth of common tree species in Europe. Here, we used eight long-term experiments with a total of 24 plots and extensive individual measurements of 1596 trees in monospecific stands of European beech (Fagus sylvatica L.), Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea (Matt.) Liebl.). Some of the experiments have been systematically surveyed since 1870. The selected plots represent a broad range of stand density, from fully to thinly stocked stands. We applied linear mixed models with random effects for analysing and modelling how tree growth and productivity are affected by stem and crown structure. We used the species-overarching relationship $$\mathrm{iv}={{a}_{0}\times v}$$ iv = a 0 × v between stem volume growth, $$\mathrm{iv}$$ iv and stem volume, $$v,$$ v , as the baseline model. In this model $${a}_{0}$$ a 0 represents the allometric factor and α the allometric exponent. Then we included tree age, mean stem volume of the stand and structural and morphological tree variables in the model. This significantly reduced the AIC; RMSE was reduced by up to 43%. Interestingly, the full model estimating $$\mathrm{iv}$$ iv as a function of $$v$$ v and mean tree volume, crown projection area, crown ratio and mean tree ring width, revealed a $$\alpha \cong 3/4$$ α ≅ 3 / 4 scaling for the relationship between $$\mathrm{iv}\propto {v}^{\alpha }$$ iv ∝ v α . This scaling corresponded with Kleiber’s rule and the West-Brown-Enquist model of the metabolic scaling theory. Simplified approaches based on stem diameter or tree mass as predictors may be useful for a rough estimation of stem growth in uniform stands and in cases where more detailed predictors are not available. However, they neglect other stem and crown characteristics that can have a strong additional effect on the growth behaviour. This becomes of considerable importance in the heterogeneous mixed-species stands that in many countries of the world are designed for forest restoration. Heterogeneous stand structures increase the structural variability of the individual trees and thereby cause a stronger variation of growth compared with monocultures. Stem and crown characteristics, which may improve the analysis and projection of tree and stand dynamics in the future forest, are becoming more easily accessible by Terrestrial laser scanning.