Separate Roots Research Articles

Is Apical Enlargement with Single Reciprocating Instruments the Key to Success in Endodontic Retreatment?

Modern endodontics has provided significant advancements, particularly in the treatment and retreatment of root canals. However, the complete removal of obturation material during retreatment remains a challenge, especially in the apical third of root canals, where complex anatomy imposes limitations. This study aimed to evaluate the effectiveness of using WaveOne Gold reciprocating instruments of different diameters and kinematics (brushing motion and pecking motion) for removing obturation material from root canals during retreatment, with a particular focus on the apical third. Thirty human maxillary molars with separate roots were selected and divided into four groups. Root canals were prepared and obturated using different WaveOne Gold instruments (Primary and Medium) and then retreated with larger diameter instruments using different kinematics. The removal of obturation material was evaluated through cone beam computed tomography (CBCT). The results were statistically analyzed using ANOVA and logistic regression. Statistical analysis revealed no significant differences between the groups regarding the type of instrument or kinematics applied. Residual obturation material was observed in approximately 60% of the samples, regardless of instrument diameter or kinematics used, indicating that complete removal of obturation material from the apical portion of root canals remains a substantial challenge. The use of larger diameter instruments, such as the WaveOne Gold Medium, and the application of brushing motion kinematics did not prove significantly more effective in removing obturation material compared to smaller diameter instruments. These findings highlight the need to explore new approaches and technologies to optimize obturation material removal, especially in complex anatomical regions like the apical third of root canals.

Synergistic effect of biochar and intercropping on lead phytoavailability in the rhizosphere of a vegetable-grass system

The effects of engineered steam exploded biochar on the phytoavailability of toxic elements in the shared- and nonshared-rhizosphere of vegetable-grass intercropping system have not been investigated yet. Therefore, we explored and elucidated the synergistic effect of pristine rape-straw biochar (BC), steam exploded BC (BCSE), KMnO4-modified BCSE (BCSEMn), and hydroxyapatite-modified BCSE (BCSEHA) on the solubility, fractionation and phytoavailability of lead (Pb) in a vegetable-grass intercropping system. In a rhizosphere box, Brassica chinensis L. (pakchoi; PC, as a vegetable) and Pennisetum polystachion L. (mission grass; MG, as a Pb hyperaccumulator), were grown in the biochar treated soil with (non-shared rhizosphere) or without (shared rhizosphere) root separation. Addition of BCSEMn and BCSEHA, particularly BCSEMn, significantly improved plant growth, photosynthetic pigment levels, and positively influenced the gas exchange attributes by suppressing oxidative stress and boosting antioxidant enzymes activities. Both biochars altered a proportion of Pb in the acid soluble to the immobile fraction and thus significantly decreased its leachability (TCLP-Pb) and bioavailability (CaCl2-extrcated Pb) by 32.7 %–33.9 % and 48.5 %–53.5 %, respectively, as compared to the control. Both biochars, particularly BCSEMn, reduced significantly the Pb content in shoots and roots of PC and MG with a significantly higher efficiency in the PC than in the MG; this was the case more in the shared than in the non-shared rhizosphere. These findings indicate the synergistic effect of BCSEMn and BCSEHA and intercropping for enhancing the grass phytostabilization capacity for Pb and reducing its uptake by edible plants in a vegetables-grass system, which could be used as a promising approach for the phytomanagement of Pb contaminated soils.

Exploring the Root Canal Morphology of Third Molars in the Bosnia and Herzegovina Population.

The objective of this study was to evaluate the root canal morphology of third molars in the Bosnia-Herzegovina population. A total of 241 extracted third molars (105 maxillary and 136 mandibular) were subjected to a clearing procedure. The specimens were categorized into ten groups based on the Alavi classification for maxillary third molars (MaxTMs), and six groups were based on the Gulabivala classification for mandibular third molars (ManTMs). Root canal type according to the Vertucci classification, the presence and position of lateral canals, and intercanal communication were analyzed using a stereomicroscope x15. MaxTMs had three roots in 77.13% of the samples. Among MaxTMs, the most common morphology was three fused roots (33.33%) and Vertucci's type VIII (54. 28% of samples in Alavi's Group IV). 60.29% of ManTMs have two separate roots (Gulabivala's Groups II and III). The most prevalent types in mesial roots were type I (41.46% in Group II) and type IV (48.78% in Group III), although type I predominated in distal roots (91.24% and 100% in Groups II and III, respectively). Single-rooted third molars usually have a root canal morphology that is more favorable for endodontic treatment. In contrast, third molars with fused roots often have more complex root canal morphology.

Endodontic Non-Surgical Management of Dens Invaginatus Type Two with Open Apex and Separate Root Sheath: A Case Report and Literature Review

Dens invaginatus (DI) is a rare developmental anomaly with an unknown etiology and different complexity. It is classified into three types according to Oehler’s classification 1957 based on the extent of invagination. This case involves an upper lateral tooth demonstrating Dens invaginatus type 2, an open apex, and a separate root sheath and diagnosis of necrotic pulp with symptomatic apical periodontitis. A cone beam computed tomography (CBCT) assessment was conducted prior to nonsurgical root canal treatment, which included apexification with bio ceramic material and internal bleaching to address both healing potential and aesthetics. The procedure was performed under an operating microscope, and a 6-month follow-up was conducted with both clinical and radiographic signs of healing.

Micro–Computed Tomographic Analysis of Radicular Dentin Thickness in Mandibular Second Molars Across Diverse Anatomic Root Variations: Identifying Potential Danger Zones

IntroductionThis study aimed to investigate radicular dentin thicknesses in mandibular second molars (MSMs), considering variations in root configuration and the morphology of the pulp chamber floor (PCF). The types of radicular grooves and potential danger zones were also identified. MethodsA total of 149 MSMs were scanned with micro–computed tomographic imaging and classified into 4 groups according to root fusion and PCF morphology as follows: (1) 45 with fused roots and C-shaped PCFs, (2) 45 with fused roots and non–C-shaped PCFs, (3) 14 with a single canal, and (4) 45 with separated roots. The first 2 groups were subdivided into Ω-shaped, U-shaped, and V-shaped radicular groove subgroups. Measurements included minimum and mean dentin thickness from the start of the radicular groove or root bifurcation extending 5 mm apically, the ratio of outer to inner dentin thickness, and the distribution of dentin thickness. ResultsΩ-shaped and U-shaped subgroups showed significant thinner minimum inner wall thickness than V-shaped subgroups at 2–5 mm from the starting point of the radicular groove in both C-shaped and non–C-shaped pulp floor categories (P < .05). The mesial roots of separated rooted MSMs showed significant thinner dentin than a non–C-shaped floor regarding minimum and mean inner thickness and mean outer thickness (P < .05). Teeth with a single canal had significantly thicker walls compared with the other 3 groups. ConclusionsIn MSMs, caution must be exercised, especially in the presence of Ω-shaped and U-shaped grooves in C-shaped roots and around the root furcation of separated roots.

Above- and Below-Ground Interactions and Interspecific Relationships in Wheat/Maize Systems

Above- and below-ground interactions play a crucial role in achieving higher yields in intercropping systems. Nonetheless, it remains unclear how these interactions impact intercropping crop growth and regulate interspecific relationships. This study aimed to quantify the impact of above- and below-ground interactions on crop yield by determining the dynamics of dry matter accumulation, photosynthetically active radiation (PAR) transmittance, and leaf area index (LAI) in intercropped wheat and maize. Three below-ground intensities were set for an intercropping system: no root separation (CI: complete interaction below ground), 48 μm nylon mesh separation (PI: partial interaction below ground), and 0.12 mm plastic sheet separation (NI: no interaction below ground). Two densities were set for maize: low (45,000 plants hm−2) and high (52,500 plants hm−2). At the same time, corresponding monoculture treatments were established. The grain yields in the CI and PI treatments were, on average, 23.7% and 13.7% higher than those in the NI treatment at high and low maize densities, respectively. Additionally, the grain yield for high density was 12.3% higher than that of low density in the CI treatment. The dry matter accumulation of intercropped wheat under the CI and PI treatments was, on average, 9.1%, 14.5%, and 9.0% higher than that in the NI treatment at the flowering, filling, and maturity stages, respectively. The dry matter accumulation of intercropped maize at the blister, milk, and physiological maturity stages increased by 41.4%, 32.1%, and 27.8%, respectively, under the CI treatment compared to the NI treatment. The PAR transmittance and LAI of maize at the V6 stage were significantly increased by increasing the intensity of below-ground interactions. This study showed that complete below-ground interaction contributed to a significant increase in the competitiveness of intercropped wheat with respect to maize (Awm) under the high-density maize treatment, especially at the filling stage of wheat. Moreover, the CI treatment enhanced the recovery effects of maize (Rm) after wheat harvesting. Increasing the intensity of below-ground interactions can significantly enhance the Awm and Rm in intercropping systems, favoring the accumulation of crop dry matter mass and light energy utilization to increase system yields.

Insights into bioactive constituents of onion (Allium cepa L.) waste: a comparative metabolomics study enhanced by chemometric tools

BackgroundOnion waste was reported to be a valuable source of bioactive constituents with potential health-promoting benefits. This sparked a surge of interest among scientists for its valorization. This study aims to investigate the chemical profiles of peel and root extracts of four onion cultivars (red, copper-yellow, golden yellow and white onions) and evaluate their erectogenic and anti-inflammatory potentials.MethodsUPLC-QqQ-MS/MS analysis and chemometric tools were utilized to determine the chemical profiles of onion peel and root extracts. The erectogenic potential of the extracts was evaluated using the PDE-5 inhibitory assay, while their anti-inflammatory activity was determined by identifying their downregulating effect on the gene expression of IL-6, IL-1β, IFN-γ, and TNF-α in LPS-stimulated WBCs.ResultsA total of 103 metabolites of diverse chemical classes were identified, with the most abundant being flavonoids. The organ’s influence on the chemical profiles of the samples outweighed the influence of the cultivar, as evidenced by the close clustering of samples from the same organ compared to the distinct separation of root and peel samples from the same cultivar. Furthermore, the tested extracts demonstrated promising PDE-5 and anti-inflammatory potentials and effectively suppressed the upregulation of pro-inflammatory markers in LPS-stimulated WBCs. The anti-inflammatory activities exerted by peel samples surpassed those of root samples, highlighting the importance of selecting the appropriate organ to maximize activity. The main metabolites correlated with PDE-5 inhibition were cyanidin 3-O-(malonyl-acetyl)-glucoside and quercetin dimer hexoside, while those correlated with IL-1β inhibition were γ-glutamyl-methionine sulfoxide, γ-glutamyl glutamine, sativanone, and stearic acid. Taxifolin, 3’-hydroxymelanettin, and oleic acid were highly correlated with IL-6 downregulation, while quercetin 4’-O-glucoside, isorhamnetin 4’-O-glucoside, and p-coumaroyl glycolic acid showed the highest correlation to IFN-γ and TNF-α inhibition.ConclusionThis study provides a fresh perspective on onion waste as a valuable source of bioactive constituents that could serve as the cornerstone for developing new, effective anti-PDE-5 and anti-inflammatory drug candidates.

Maize lowers the N2O emissions from maize/soybean intercropping

Interspecific interactions between intercropped maize and soybean are expected to cycle soil nitrogen efficiently and avoid N2O emissions. However, the unique interactions of maize and soybean with nitrogen cycling bacteria makes it hard to predict the crop-specific impact on soil N2O production. We conducted a field microcosm experiment with root separation to simulate monoculture and intercropping with maize and soybean. Intercropped maize reduced the N2O emissions by 16–41%, compared to monoculture maize. This was related to reduced nitrification by ammonia-oxidizing bacteria and denitrification reactions (as indicated by the abundance of nirS and nirK gene copies), as well as drier soil conditions and lower soil NO3−-N levels. Soil N2O emissions were the same in monoculture and intercropped soybean, suggesting stable denitrification (based on nirS, nirK and nosZ genes) with constant soil physicochemical conditions. As monoculture maize can stimulate soil N2O emission through denitrification, this work justifies the adoption of maize-soybean intercropping as a low N2O-emitting practice in sustainable agriculture, due to its beneficial effects on soil biology and biochemistry.

Application of Digital Correlation-Spectral Analysis for Identification, Classifiaction and Separation of Plant Roots and Plant Root Tissues: Simple Low-Cost Alternatives for Laser Diffractometer Based 2D FFT Pattern Recognition Techniques

Application of Digital Correlation-Spectral Analysis for Identification, Classifiaction and Separation of Plant Roots and Plant Root Tissues: Simple Low-Cost Alternatives for Laser Diffractometer Based 2D FFT Pattern Recognition Techniques

Wheat root exudates suppress faba bean Fusarium wilt disease

AbstractContinuous cultivation of faba beans often results in a high occurrence of Fusarium wilt. Nevertheless, this issue can be successfully managed through wheat‐faba bean intercropping. Our objective is to elucidate the function of non‐host wheat in combating faba bean Fusarium wilt. We assessed the impact of wheat on the development of faba bean Fusarium wilt through field and pot experiments, and examined and identified the compounds in the root exudates of wheat. The influence of wheat root exudates on Fusarium commun mycelial growth and spore multiplication was investigated through indoor culture experiments. Wheat‐faba bean intercropping significantly reduced the occurrence of Fusarium wilt in field trials. Root separation experiments in pots indicated that wheat root exudates might play a vital role in this outcome. The exogenous addition of wheat root exudates to faba bean grown alone notably decreased the occurrence and severity of Fusarium wilt. Furthermore, the exogenous addition of wheat root exudates effectively hindered the growth and reproduction of Fusarium commun's mycelium. And, wheat root exudates contained six compounds with relatively high concentrations, including salicylic acid, p‐hydroxybenzoic acid, tartaric acid, malic acid, glutamic acid, and threonine, all of which inhibited the growth and spore formation of Fusarium commun. In a wheat‐faba bean intercropping system, these six compounds found in the root exudate of non‐host wheat can help control Fusarium wilt in faba bean by inhibiting the mycelial growth and sporulation of Fusarium commun.

문법 모형에서 어휘선택 이전 ‘의도 접합부’ 고려의 필요성

This article aims to integrate "Grammatical models" and "Performance models". Accordingly, the purpose of this article is to elucidate the role that existing grammatical models play in performance models and to supplement necessary discussions. Existing grammatical models incorporate an 'Interface' to serve as a link between them, taking subsequent utterances into consideration. However, within performance models, the position of grammatical models aligns with the 'Formulator', situated between the 'Conceptualizer' and 'Articulator'. It has been identified that not only is an 'Interface' needed for connection with the 'Articulator', but an 'Interface' for connection with the 'Conceptualizer' is also imperative. Therefore, this article argues for the establishment of an 'Intentional Interface' as a connecting link between the 'Conceptualizer' and 'Formulator'. The theoretical basis for this argument is explained through the lexical selection process in the lexicon. In summary, while existing grammatical models do not delve into how lexical selection occurs in the lexicon, this article posits that lexical selection is based on the 'Intent' interpreted in the 'Intentional Interface'. This explanation, I believe, provides a theoretical foundation for explaining the 'Generation of Idiomatic expression', 'Generation of Active and Passive expressions', and 'Root separation'.

Dissimilarity in root traits and spatial distribution promotes the productivity of Piper nigrum L. and tree species in mixture systems

Background and aimsClarifying why species mixtures produce greater biomass compared to monocultures is important for understanding the effect of biodiversity in natural and agricultural systems. At present, it remains unclear whether differential root traits and spatial distribution between the liana and tree species can promote productivity of mixtures. MethodsA 4-month glasshouse experiment and a 3-year field trial were conducted to examine the influence of root traits and the vertical and horizontal root distribution on productivity of independently supported liana Piper nigrum (Pn) and five other species. In the glasshouse experiment, Pn was grown in monoculture or mixed with one of five species: Coffea arabica, Areca catechu, Artocarpus heterophyllus, Camellia oleifera, and Coffea canephora. In the field trial, the Pn/Ac system and each monoculture were tested. ResultsCompared with monoculture, all Pn and mixture systems showed a positive net effect and a high complementarity effect on shoot biomass. The variation in complementarity effect was mainly associated with dissimilarity in the multidimensional root space trait and a few specific individual traits (root phosphatase activity and mycorrhizal colonization) between Pn and the neighbors. In the field, Pn in the mixture increased proportion of root length in the 20–40 cm soil layer and allocated less root length in the space shared between Pn and Ac, thus achieving spatial separation of roots and promoting the final yield. ConclusionThese findings suggest that the dissimilarity in root traits and spatial distribution may be an important mechanism for promoting the productivity of mixtures of liana and tree species.

Root resection of multirooted teeth with premolarization of mandibular molar for successful oral rehabilitation

Abstract Root resection procedures are indicated in the treatment of periodontal furcation involvement and root fractures in one of the roots of multirooted teeth. Their long-term prognosis is comparable to that of implants. The present article is a case report of root separation and removal of the mesial root along with crown in mandibular first molar which was successfully employed as a part of the oral rehabilitation procedure.

A New Methodology to Determine the Orifice for Root Canal Configurations in First Permanent Molar Root and Canal Morphologies Using Micro-Computed Tomography.

The distinction between where the pulp chamber ends and the root canal system begins is poorly defined within the existing literature. This paper aimed to describe a range of accurate methods to define the transition from pulp chamber to root canal in different first molar root morphologies using micro-focus computed tomography (micro-CT). The sample consisted of 86 mandibular and 101 maxillary first molars from the skeletal collections housed in the Department of Anatomy and Histology of the Sefako Makgatho Health Sciences University and the Pretoria Bone Collection. A stepwise approach using the cemento-enamel junction (CEJ) and dedicated landmarks was followed to create an automated cross-sectional slice. Transition from pulp chamber to root canal could be accurately determined on maxillary and mandibular teeth. The occurrence of two separate roots in mandibular molars was 97.7%, with the remaining 2.3% having an additional disto-lingual root, with no mandibular molars displaying fused roots. In the maxillary molars, 92.1% had three separate roots and 7.9% displayed root fusion. Within this group, one tooth displayed a C-shaped root canal configuration and one a mesotaurodont-type morphology. The suggested methodology to determine orifice location was found to be appropriate in all morphological types.

Influence of different working lengths on the shaping ability of Reciproc Blue in the apical third and apical foramen

Aim: This study aimed to assess the shaping ability of Reciproc Blue in the apical third and apical foramen of moderately curved canals at different working lengths (WLs), by micro-computed tomography. Methods: Thirty-six mesial roots (mesiobuccal and mesiolingual canals) were included, each with 2 separate root canals and independent apical foramina, according to type IV of Vertucci’s classification of first and second mandibular molars. The canals were instrumented at three different WLs: G-1, 1mm short of the major apical foramen; G0, at the major apical foramen; G+1, 1mm beyond the major apical foramen. The groups were assessed for changes in root canal volume and untouched wall area in the apical third. Groups G0 and G+1 were also compared for percentage of untouched walls at the apical foramen. One-way ANOVA (post hoc Tukey test) and Student’s t-test adopted a 5% level of significance. Results: Root canal volumes (mm3) in the apical third were 22.86±10.46, 44.48±24.91, and 55.71±21.32 in G-1, G0 and G+1, respectively. G-1 volume following instrumentation increased significantly less than that of G0 or G+1 (P&gt;.05); G0 did not differ from G+1. The percentage of untouched wall area in the apical third did not differ among the three groups (P&gt;.05). G0 and G+1 did not differ regarding untouched walls in the major apical foramem walls. Conclusion: Extending the WL from 1mm short of the apical foramen to a point at and beyond the WL increases the apical third volume without increasing the prepared area. Untouched surface areas of the apical foramen were not modified by instrumentation at or beyond the foramen.

Quercetin Ameliorates Neuropathic Pain after Brachial Plexus Avulsion via Suppressing Oxidative Damage through Inhibition of PKC/MAPK/ NOX Pathway.

Brachial plexus avulsion (BPA) animally involves the separation of spinal nerve roots themselves and the correlative spinal cord segment, leading to formidable neuropathic pain of the upper limb. The right seventh cervical (C7) ventral and dorsal roots were avulsed to establish a neuropathic pain model in rats. After operation, rats were treated with quercetin (QCN) by intragastric administration for 1 week. The effects of QCN were evaluated using mechanical allodynia tests and biochemical assay kits. QCN treatment significantly attenuated the avulsion-provoked mechanical allodynia, elevated the levels of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) and total antioxidant capacity (TAC) in the C7 spinal dorsal horn. In addition, QCN administration inhibited the activations of macrophages, microglia and astrocytes in the C6 dorsal root ganglion (DRG) and C6-8 spinal dorsal horn, as well as attenuated the release of purinergic 2X (P2X) receptors in C6 DRG. The molecular mechanism underlying the above alterations was found to be related to the suppression of the PKC/MAPK/NOX signal pathway. To further study the anti-oxidative effects of QCN, we applied QCN on the H2O2-induced BV-2 cells in vitro, and the results attested that QCN significantly ameliorated the H2O2-induced ROS production in BV-2 cells, inhibited the H2O2-induced activation of PKC/MAPK/NOX pathway. Our study for the first time provided evidence that QCN was able to attenuate pain hypersensitivity following the C7 spinal root avulsion in rats, and the molecular mechanisms involve the reduction of both neuro-inflammatory infiltration and oxidative stress via suppression of P2X receptors and inhibition of the activation of PKC/MAPK/NOX pathway. The results indicate that QCN is a natural compound with great promise worthy of further development into a novel therapeutic method for the treatment of BPA-induced neuropathic pain.

Stress control and bicuspidization

Mandibular molars being the first teeth to erupt in the oral cavity have high caries susceptibility index, deprivation in its maintenance may lead to serious problem like furcation involvement. Recent advances in dentistry and the desire of patients to maintain their dentition, have lead to treatment of teeth that once would have been removed. Bicuspidization is a procedure in which separation of distal and mesial roots of mandibular molar with their coronal portion are done. This separation helps to eliminate the existing furcation and ensure effective oral hygiene maintenance. The mandibular molar teeth with severe bone loss at interradicular area may be retained of their roots. In this case report, a basic procedure of bicuspidization of right first mandibular molar followed by prosthetic treatment has been presented.

Standardization of vertical root resection during socket shield technique in immediate implant placement

Objectives. The aim of the present study was to standardize an accurate and significant technique of root separation during socket shield technique. Patients and methods. Two phases of the study were conducted. In vitro study was performed on 20 extracted single-rooted anterior teeth. The second phase was clinical application of the new technique on 10 patients seeking to restore their badly decayed anterior teeth in the esthetic area with immediate implant placement utilizing the socket shield technique. Decoronation was done. The root canal was mechanically enlarged by means of manual assorted files. Canals were further enlarged with Gates Glidden drills. Peeso Reamer drills were used till the root was entirely separated into two parts (buccal &amp; palatal). The palatal root was cautiously removed when the labial and palatal root halves were sufficiently separated. In case the root to be removed was endodontically treated, Gutta-percha was mechanically removed using Gates Glidden, &amp; Gutta-percha solvent to remove the coronal and apical parts. Outcomes. Using manual endodontic K-files, Gates Glidden burs, and Peeso Reamer’s drills in separating the single-rooted teeth into two halves is a reproducible, and reliable procedure during socket shield technique. Conclusions. This technique prevents possible complications of root sectioning during socket shield technique with immediate implant placement. It preserves surrounding soft tissue structures, and labial shield during shield preparations, maintains the integrity of the labial plate of bone during extraction. Additionally, it offers total root apex removal by entirely separating the palatal portion from the labial shield.

Qualitative properties, bifurcations and chaos of a discrete predator–prey system with weak Allee effect on the predator

In this work, the qualitative properties of the fixed points in the non-hyperbolic and degenerate cases, codimension-one bifurcations and Marotto’s chaos of a discrete predator–prey system with weak Allee effect on the predator are investigated. Utilizing the center manifold theorem and the reduction principle, the qualitative property of each fixed point in the non-hyperbolic case is explored. Based on the approximate flow theory, the qualitative property of the boundary fixed point in the degenerate case is investigated. Making use of the center manifold theorem and the bifurcation theory, all the potential codimension-one bifurcation types of the co-existence fixed point are explored, including flip bifurcation and Neimark–Sacker bifurcation. For each type of these bifurcations, not only the concise non-degenerate condition expressed by the system parameters is given, but also the analytical expression of the system orbit caused by the bifurcation is derived. Based on the non-negativity of the bifurcation critical values, the non-resonant and non-degenerate conditions for the occurrence of these bifurcations, the system parameter plane is divided into several regions using tools such as the polynomial complete discriminant system theory, real root separation theory, dichotomy method, implicit function theorem and Cardan’s formula. In each region, the direction and stability of these bifurcations are studied, which helps to theoretically explain the impact of Allee effect on the system. By proving that the co-existence fixed point is a snap-back repeller under appropriate conditions, it is obtained that the system is chaotic. Numerical simulations are completely consistent with all the theoretical analyses. The research results show that the impact of Allee effect on the population system depends not only on the assumption and construction of the system, but also on the system parameter and initial value of the system.

Furcation area and root proximity of molars as a risk indicator of periodontitis: a cone‑beam computed tomography-based study.

This study assessed the root proximity in molars and the furcation area (FA) in the first root separation point (RSP) using cone‑beam computed tomography (CBCT) and evaluated the association between the furcation area of molars and periodontal status of the patients. A total of 264 molar teeth in 66 participants were included in the study. The control group consisted of 110 molar teeth of participants, and 154 molar teeth were included in periodontitis group, which consisted of only stage II and III periodontitis patients. FA, RSP, and root proximities were measured in axial slices, and bone resorption rates were measured in sagittal slices. Both maxillary and mandibular molar groups had significantly less FA in periodontitis group than in controls (p < 0.005), and there were significant relationships between the degree of bone resorption in molars and FA and furcation grades (p < 0.001). According to regression analysis, the risk of periodontitis increased by 1.011 times as total FA decreased (p < 0.001), and periodontitis risk of maxillary molar was 1.693 times higher than mandibular molars but not found to be statistically significant (p = 0.152). When assessing the root proximity between molar teeth, maxillary molars showed significantly higher root proximity in CEJs than mandibular molars in both periodontitis and control groups (p < 0.05). The results indicate that the association between FA and the degree of bone resorption and root proximity of maxillary molars might be considered as a risk indicator for bone resorption in molars and might play a role during disease progression.