Brassinosteroids Mitigate Cadmium Effects in Arabidopsis Root System without Any Cooperation with Nitric Oxide

The heavy metal cadmium (Cd) affects root system development and quiescent center (QC)-definition in Arabidopsis root-apices. The brassinosteroids-(BRs)-mediated tolerance to heavy metals has been reported to occur by a modulation of nitric oxide (NO) and root auxin-localization. However, how BRs counteract Cd-action in different root types is unknown. This research aimed to find correlations between BRs and NO in response to Cd in Arabidopsis’s root system, monitoring their effects on QC-definition and auxin localization in root-apices. To this aim, root system developmental changes induced by low levels of 24-epibrassinolide (eBL) or by the BR-biosynthesis inhibitor brassinazole (Brz), combined or not with CdSO4, and/or with the NO-donor nitroprusside (SNP), were investigated using morpho-anatomical and NO-epifluorescence analyses, and monitoring auxin-localization by the DR5::GUS system. Results show that eBL, alone or combined with Cd, enhances lateral (LR) and adventitious (AR) root formation and counteracts QC-disruption and auxin-delocalization caused by Cd in primary root/LR/AR apices. Exogenous NO enhances LR and AR formation in Cd-presence, without synergism with eBL. The NO-signal is positively affected by eBL, but not in Cd-presence, and BR-biosynthesis inhibition does not change the low NO-signal caused by Cd. Collectively, results show that BRs ameliorate Cd-effects on all root types acting independently from NO.

Aluminum Stress Induces Irreversible Proteomic Changes in the Roots of the Sensitive but Not the Tolerant Genotype of Triticale Seedlings

Triticale is a wheat–rye hybrid with a higher abiotic stress tolerance than wheat and is better adapted for cultivation in light-type soils, where aluminum ions are present as Al-complexes that are harmful to plants. The roots are the first plant organs to contact these ions and the inhibition of root growth is one of the first plant reactions. The proteomes of the root apices in Al-tolerant and -sensitive plants were investigated to compare their regeneration effects following stress. The materials used in this study consisted of seedlings of three triticale lines differing in Al3+ tolerance, first subjected to aluminum ion stress and then recovered. Two-dimensional electrophoresis (2-DE) was used for seedling root protein separation followed by differential spot analysis using liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS/MS). The plants’ tolerance to the stress was evaluated based on biometric screening of seedling root regrowth upon regeneration. Our results suggest that the Al-tolerant genotype can recover, without differentiation of proteome profiles, after stress relief, contrary to Al-sensitive genotypes that maintain the proteome modifications caused by unfavorable environments.

Orthodontic Treatment of Bilateral Transposition of Maxillary Canines and Lateral Incisors

Dental transposition is a severe disturbance of tooth position and its eruptive sequence. It may affect any tooth, and it may occur at any location within the dental arch, although some teeth may be more frequently affected than others. There are several types of dental transposition, and their classification depends on the type of teeth involved. The aetiology of transposition is not very clear and has always been the subject of controversies, and it is still not completely understood. The prevalence of dental transposition and the factors related to this dental anomaly have been well documented in the literature. When treating dental transposition, many factors which may affect the treatment results must be considered, such as aesthetics, occlusion, treatment duration, patient comfort, patient cooperation, and periodontal support. Various treatment options are currently available for the treatment of dental transposition. Successful treatment outcomes depend on the patient’s age, concern about facial and dental aesthetics, motivation of the patient, functional requirements, type of malocclusion, and the position of the root apices. The present case report is aimed at outlining the orthodontic treatment of a young adult patient diagnosed with bilateral maxillary canine-lateral incisor transposition.

Evaluation of the effect of periapical lesions and other odontogenic conditions on maxillary sinus mucosal thickness characteristics and mucosal appearance: A CBCT study

Background. This retrospective study aimed to investigate the effect of various dental and maxillary sinus variables on maxillary sinus mucosal thickness (MT). The variables included periodontal bone loss (PBL), periapical status, dental restorations of posterior maxillary teeth, and the distance from the root apices to the sinus mucosa. Methods. Cone-beam computed tomography (CBCT) images of the maxillary sinuses (n=600) in 300 patients were examined. The sinus MT and the distance of the roots from maxillary sinuses were measured. Apical lesions of the roots, PBL, and situations of adjacent teeth were recorded. The relationships between these conditions and MT and characterization of MT were evaluated. The Kruskal–Wallis H test was used to compare groups due to the non-normal distribution of the data. The relationship between categorical variables was analyzed using chi-squared test. Results. There was a significant correlation between maxillary sinus MT and periapical lesions, PBL, and restorations (P<0.05). MT increased as the apical lesions of premolar teeth enlarged (P<0.05, P=0.022). MT increased in cases of mild PBL of molar teeth (P=0.041). Conclusion. In this retrospective study, the MT significantly increased in patients with periapical lesions, inadequate endodontic treatment, increased PBL, and inadequate dental restorations.

Local Irradiation of Mouse Tooth Germ Gives Insight into the Direct Effects of Irradiation on Root Development

To elucidate the mechanism underlying the failure of root formation after irradiation, we established a method of local irradiation of the molar tooth germ and demonstrated that radiation directly affected dental root development. In the current study, to locally irradiate the lower first molars of 5-day-old C57BL/6J mice, we used lead glass containing a hole as a collimator. We confirmed that our local irradiation method targeted only the tooth germ. The irradiated root was immature in terms of apical growth, and dentin formation was irregular along the outside of the root apices. Moreover, calcified tissue apically surrounded Hertwig's epithelial root sheath, which disappeared abnormally early. This method using a local irradiation experimental model will facilitate research into radiation-induced disorders of dental root formation.

Incisor position and alveolar bone thickness:

ABSTRACT Objectives To evaluate incisor position and its relationship to alveolar bone in untreated optimal occlusions and in untreated Class II malocclusions. Materials and Methods Fifty-seven lateral cephalograms of individuals with naturally occurring optimal occlusions (mean age = 23 years) were used to assess positions of central incisors and their relationships to alveolar bone. Data were compared to a sample of 57 individuals with untreated Class II malocclusions with concurrent anterior-posterior (AP) skeletal discrepancies (mean age = 16.9 years). Results Significant intergroup differences were found for AP jaw relationship, maxillary alveolar bone thickness, mandibular incisor inclination, maxillary incisor root distance to labial surface of alveolar bone, and mandibular incisor root apex distance to labial surface of alveolar bone. Small differences between females and males existed for several variables. In both samples, maxillary incisor roots were located closer to the labial surface of alveolar process than to the palatal surface by roughly a 2:1 ratio. Mandibular incisor root apices were generally equidistant from the labial and lingual surfaces of the alveolus in the optimal sample but closer to the lingual surface in the Class II sample. Conclusions Maxillary incisors tend to occupy the anterior one-third of the alveolus in untreated individuals, regardless of AP interarch dental relationships or AP jaw relationships. Mandibular incisor root apices tend to be centered within the alveolus in untreated optimal occlusions but are more positively inclined, and their root apices are more posterior in untreated Class II malocclusions.

Comparison of the Effect of Three Irrigation Techniques and Root Canal Preparation Size on Sodium Hypochlorite Penetration into Root Canal Dentinal Tubules

Objective. This study aims to compare the effects of conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), and innovative sonic-powered irrigation (EDDY) on the penetration of sodium hypochlorite (NaOCl) solutions into root canal dentinal tubules at different levels of the root canal. Materials and Methods. One hundred ninety-two extracted first mandibular premolars of 17- to 25-year-old patients were decoronated 13 mm from the root apices and separated into two groups according to apical preparation sizes (APS) 25 and 40. The root canals were dried with a paper point and stained in crystal violet for 72 hours. Each APS group was separated into three groups according to irrigation techniques, as follows: CSI, PUI, and EDDY. Roots were perpendicularly resected to the long axis at three levels (coronal, middle, and apical). Photomicrographs were taken of all three cross-sections of each tooth under a stereomicroscope. The depth of the bleached zone was measured with ImageJ software. The data were analyzed by Welch’s analysis of variance and an independent t-test ( p = 0.05). Results No penetration was found at the apical level in the CSI25, CSI40, and PUI25 groups. The EDDY25 and EDDY40 groups showed the most significant penetration at the middle and apical levels compared to the other groups ( p < 0.05). Conclusions. Within the limitations of this study, irrigation techniques and APS affect the penetration depth of NaOCl into the root canal dentinal tubules. In terms of irrigation techniques, the penetration was deepest when EDDY was used, followed by PUI and CSI. In terms of APS, NaOCl penetrated deeper into APS40 than APS25. The use of the EDDY irrigation technique in APS25 can improve the penetration of NaOCl into root canal dentinal tubules at the apical level.

Polarly localized receptor-like kinases PXC2 and IRK act redundantly during Arabidopsis root development in the radial axis

SUMMARYIn plants, coordination of cell division and differentiation is critical for tissue patterning and organ development. Directional cell signaling and cell polarity have been proposed to participate in coordination of these developmental processes. For instance, a leucine-rich repeat receptor-like kinase (LRR-RLK) named INFLORESCENCE AND ROOT APICES KINASE (IRK) functions to restrict stele area and inhibit longitudinal anticlinal divisions (LADs) in the endodermis where it is polarly localized. The LRR-RLK most closely related to IRK is PXY/TDR CORRELATED 2 (PXC2) and we find that PXC2 shows similar polarized accumulation as IRK in root cell types. To further understand how these proteins operate in directional cell-cell signaling and root development we explored PXC2 function. pxc2 roots have an increase in stele area, indicating that PXC2 also functions to restrict stele size. Additionally, compared to either single mutant, irk pxc2 roots have an enhanced phenotype with further increases in endodermal LADs and stele area indicating redundant activities of these receptors. The double mutant also exhibits abnormal root growth, suggesting broader functions of PXC2 and IRK in the root. However, PXC2 is not functionally equivalent to IRK, as endodermal misexpression of PXC2 did not fully rescue irk. We propose that PXC2 is at least partially redundant to IRK with a more predominant role for IRK in repression of endodermal LADs. Our results are consistent with the hypothesis that repression of specific endodermal cell divisions and stele area through a PXC2/IRK-mediated directional signaling pathway is required for coordinated root growth and development.SIGNIFICANCE STATEMENTIn the root, coordination of growth and developmental processes is critical for organ function and directional cell-to-cell signaling and cell polarity are implicated in these processes. Our studies indicate that laterally polar transmembrane receptor kinases, PXC2 and IRK, have redundant functions in restriction of specific endodermal cell divisions and stele size, and are important for gravitropic root growth.

Autotransplantation of Two Immature Third Molars with the Use of L-PRF

Tooth autotransplantation is a procedure which provides the extraction of an erupted or impacted tooth and its repositioning to another site in the oral cavity. This Case Report describes a successful case of two autotransplantations of open-apex mandibular third molars in place of the hopeless first mandibular molars with the use of L-PRF in a growing patient. A 15-year-old male patient was referred to the Dental Clinic for the extractions of the two hopeless mandibular first molars. Autotransplantation was considered the best treatment option for both sites 36 and 46, because the presence of two impacted mandibular third molars (38 and 48) with an incomplete root formation. Teeth 36 and 46 were extracted and replaced with teeth 38 and 48. The patient had an uneventful healing. At follow-up visits, the two autotransplanted teeth showed physiologic mobility, absence of inflammation and discomfort, and absence of infection; probing depth values were within normal range, and the vitality tests were positive. After 2 years, the teeth in position 36 and 46 showed absence of infection and mobility, and positive pulp vitality tests and the radiographic examinations exhibited closure of the root apices as well as absence of any periapical radiolucency or root resorption. Tooth autotransplantation is a good treatment option in case of tooth loss offering an alternative to traditional or implant-supported prosthesis especially for growing patients.