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1.
Prog Orthod ; 22(1): 5, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33523325

RESUMEN

BACKGROUND: The influence of different biological agents on the rate of orthodontic tooth movement (OTM) has been extensively reviewed in animal studies with conflicting results. These findings cannot be extrapolated from animals to humans. Therefore, we aimed to systematically investigate the most up-to-date available evidence of human studies regarding the effect of the administration of different biological substances on the rate of orthodontic tooth movement. METHODS: A total of 8 databases were searched until the 16th of June 2020 without restrictions. Controlled randomized and non-randomized human clinical studies assessing the effect of biological substances on the rate of OTM were included. ROBINS-I and the Cochrane Risk of Bias tools were used. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: A total of 11 studies (6 randomized clinical trials and 5 prospective clinical trials) were identified for inclusion. Local injections of prostaglandin E1 and vitamin C exerted a positive influence on the rate of OTM; vitamin D showed variable effects. The use of platelet-rich plasma and its derivatives showed inconsistent results, while the local use of human relaxin hormone showed no significant effects on the rate of OTM. LIMITATIONS: The limited and variable observation periods after the administration of the biological substances, the high and medium risk of bias assessment for some included studies, the variable concentrations of the assessed biological agents, the different experimental designs and teeth evaluated, and the variety of measurement tools have hampered the quantitative assessment of the results as originally planned. CONCLUSIONS AND IMPLICATIONS: Despite the methodological limitations of the included studies, this systematic review provides an important overview of the effects of a variety of biological agents on the rate of tooth movement and elucidates the deficiencies in the clinical studies that have been conducted so far to evaluate the effectiveness of these agents in humans, providing some guidelines for future robust research. TRIAL REGISTRATION: PROSPERO ( CRD42020168481 , www.crd.york.ac.uk/prospero ).


Asunto(s)
Técnicas de Movimiento Dental , Diente , Animales , Factores Biológicos , Humanos , Estudios Prospectivos , Proyectos de Investigación
2.
Artículo en Inglés | MEDLINE | ID: mdl-33528446

RESUMEN

MAPA-cision, named after those who first introduced the method, is a novel simplified regenerative technique for periodontal-orthodontic cases that can be used in all circumstances where bone thickening is required. It is an innovative, minimally invasive piezoelectric surgical procedure designed to facilitate orthodontic tooth movement while simultaneously increasing bone thickness with guided bone regeneration principles. A new regenerative device consisting of a resorbable collagen membrane with filling materials (a "bone bundle" or "small sausage") is inserted through a tunneling procedure to increase the bone envelope width by allowing the teeth to move within an enhanced periodontal support.


Asunto(s)
Técnicas de Movimiento Dental , Diente , Regeneración Ósea , Humanos
3.
Artículo en Inglés | MEDLINE | ID: mdl-33528450

RESUMEN

There is a need to modify the definition of attached gingiva (AG) as it applies to healthy and diseased teeth and implants. There are two parts to this new definition: Part A is when the biologic width is supracrestal (epithelial attachment and gingival fibers) and is attached to a healthy tooth or tissue-level implant, and the zone of AG is measured from the base of the sulcus to the mucogingival junction (MGJ); Part B is when the biologic width is subcrestal-as with infrabony defects on periodontally involved teeth, periodontally involved tissue-level implants, and bone-level implants placed at or below the bone crest-and the zone of AG is measured from the bone crest (not the base of the sulcus) to the MGJ. Further, what the AG is actually attached to around teeth and different types of implants, and the clinical significance of these differences, are thoroughly discussed.


Asunto(s)
Implantes Dentales , Diente , Inserción Epitelial , Encía , Humanos
4.
Niger J Clin Pract ; 24(2): 220-224, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33605912

RESUMEN

Objective: The objective was to in-vitro evaluate the mode of failure of abutments supporting fixed partial dentures (FPDs) via different retention techniques. Materials and Methods: Thirty-six implants with diameter and length of 4.5 and 13 mm, respectively, were used to prepare 18 samples of FPDs. Based on the variations on abutment's design, the FPDs were divided into three groups: Group A is cement-based retention; Group B is screw-based retention; and Group C is multiunit screw-based retention. Using a chewing simulator, cyclic loads of 1,250,000 load cycles with the load of 70N were applied on all samples to simulate 5 years of human functional chewing. The samples were loaded until failure using an electromechanical test machine. Sample-size estimation was done and fracture-load values were recorded as means and corresponding standard deviations; and group comparisons were done using one-way analysis of variance and Tukey's post hoc tests. A P value below 0.01 was nominated as an indicator of statistical significance. Results: In total, 36 samples (12 implant-abutment connections per group) were assessed. Abutment bending was observed in 6 (50%), 6 (50%) and 6 (50%) samples in groups A, B and C, respectively. De-attachment of the FPD form the abutment occurred in 5 (41.7%) and 5 (41.7%) samples in groups A and C, respectively. Screw fracture and fracture of FPD at the connector side occurred in 1 (8.3%) and 1 (8.3%) sample in groups A and C, correspondingly. Failure of the FPD was more often encountered in groups A (100%) and C (100%), compared to group B (50%). Conclusion: All abutments underwent failures under cyclic loading with abutment bending being the most common failure mode. Cement- and multi-screw-supported abutments fail more often than screw-supported abutments.


Asunto(s)
Dentadura Parcial Fija , Diente , Pilares Dentales , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Humanos , Masticación , Ensayo de Materiales
5.
Niger J Clin Pract ; 24(2): 269-276, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33605919

RESUMEN

Background: Diabetes and periodontitis are two chronic inflammatory diseases sharing specific etiopathogenetic mechanisms, and both cause severe inflammation and destruction. Aims: The present study aimed to determine the receptor expressions of peroxisome proliferative-activated receptor (PPAR)-γ, retinoid X receptor (RXR)-α, vitamin D receptor (VDR), and nuclear factor kappa B (NF-κB) expressions in healthy gingiva and diseased gingival samples with or without diabetes. Methods: Forty-five participants as (1) healthy controls (C), (2) periodontitis group (P), and (3) diabetes and periodontitis group (DP) were enrolled. Plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment levels (CAL), and bleeding on probing (BOP) were recorded in all participants. Two gingival biopsies from each participant were obtained, and one underwent histological tissue processing while the other underwent qRT-PCR analysis of nuclear receptors. Inflammatory and fibroblast cell counts, PPAR-γ, RXR-α, VDR, and NF-κB were evaluated. Results: Fibroblast cells were lowest in the DP group and highest in the healthy group. PPAR-γ, VDR, RXR, and NF-κB expressions were higher in the healthy controls in the qRT-PCR analysis and similar in the other groups. Immunohistochemistry analysis also showed similar results. Conclusion: qRT-PCR results concluded that healthy gingival samples had higher PPAR-γ, RXR, VDR, and NF-κB expressions, and immunohistochemistry findings supported the results. In addition, healthy gingiva contained higher fibroblast cells and lower inflammatory cells.


Asunto(s)
Diabetes Mellitus , Periodontitis , Diente , Encía , Humanos , Índice Periodontal
6.
Int J Oral Sci ; 13(1): 4, 2021 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-33547271

RESUMEN

During embryonic development, organs undergo distinct and programmed morphological changes as they develop into their functional forms. While genetics and biochemical signals are well recognized regulators of morphogenesis, mechanical forces and the physical properties of tissues are now emerging as integral parts of this process as well. These physical factors drive coordinated cell movements and reorganizations, shape and size changes, proliferation and differentiation, as well as gene expression changes, and ultimately sculpt any developing structure by guiding correct cellular architectures and compositions. In this review we focus on several craniofacial structures, including the tooth, the mandible, the palate, and the cranium. We discuss the spatiotemporal regulation of different mechanical cues at both the cellular and tissue scales during craniofacial development and examine how tissue mechanics control various aspects of cell biology and signaling to shape a developing craniofacial organ.


Asunto(s)
Cráneo , Diente , Diferenciación Celular , Morfogénesis , Transducción de Señal
7.
Int J Esthet Dent ; 16(1): 76-128, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33502132

RESUMEN

Many clinicians are unsure of how to develop a comprehensive plan of treatment for patients who present with multiple problems and pathologies. In order to efficiently plan appropriate treatment for such complex patient cases, the clinician needs to either have or develop the necessary knowledge of evidence-based information on the predictability of available clinical procedures. The clinician also needs to understand the correct sequence in which such treatment is applied, and perfect the skills required for carrying out that treatment. Since most clinicians have not acquired all the knowledge and skills necessary for this task, an interdisciplinary approach to treatment is typically required. This article provides a practical step-by-step approach to planning comprehensive interdisciplinary treatment focused primarily on the teeth as they relate to each other and to the structures that surround them. The approach is based on the answers to six questions that are grouped into three steps: 1) evaluation of the teeth relative to the face and lips; 2) assessment of anterior tooth dimensions; and 3) analysis of the anteroposterior and maxillomandibular relationships. The information obtained must then be related to the patient's skeletal framework, periodontal status, caries susceptibility, and biomechanical risk assessment in order to formulate a clear and complete plan of treatment.


Asunto(s)
Estética Dental , Diente , Humanos
9.
Int J Esthet Dent ; 16(1): 10-32, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33502129

RESUMEN

Every human smile is unique and special, reflecting the different shapes, textures, and colors of the teeth as well as their combinations. This uniqueness conveys a direct and specific message when it comes to creating a new smile design. Dentists need to consider the 'unity of the whole' concept in this task, which involves bringing together biology, structure, function, and esthetics to create the fifth dimension of the smile. This approach is quite different from the traditional one. A smile reflects the personality and emotional state of the patient, and the translation of this into a new smile design occurs in various ways. This can be performed either through analog methods or digitally; however, the use of visual language will assist the dentist and dental technician in the creation of a personalized smile design. Nowadays, with the significant digital advances that have occurred in dentistry, there are systems on the market that help the dental team to create a personalized new smile design for each specific patient. The Rebel system is one example of such a system. It is actually a virtual laboratory that creates individualized smile designs in three dimensions. The system, with its very sophisticated artificial intelligence (AI)-based software, immediately creates a digital wax-up (STL file). It is therefore simple to use for dentists and dental technicians at all skill levels because the direct mock-up and wax-up stages are eliminated.


Asunto(s)
Inteligencia Artificial , Diente , Estética Dental , Humanos , Sonrisa , Programas Informáticos
10.
Arch Oral Biol ; 122: 104999, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33340922

RESUMEN

OBJECTIVE: In this paper we aim to provide baseline data and model the changes of Ca, P and Mg throughout life in the mandibular bone, enamel and dentin of red (Cervus elaphus) and fallow deer (Dama dama) in Mediterranean ecosystems. DESIGN: Through a cross-sectional study of cervids from 1.5 to 20 yrs old, hunted between 1990 and 1997, we apply generalized additive models (GAMs) with data from scanning-electron-microscope with energy-dispersive X-ray (FESEM-EDX) and inductively coupled plasma-mass spectrometry (ICP-MS) analyses. RESULTS: The mineral content varied in a similar range to that reported for other ruminants. However, we detected lower Ca content values, while more similar results were obtained for P and Mg contents, which led to relatively lower Ca/P ratios and higher Ca/Mg in our deer at that time. A significantly lesser pattern of decreasing mineral content with aging was detected in the fallow deer males, similarities were found between the sexes, and significantly less resistance to demineralization was observed in dentin compared to bone. We discuss how the basic macromineral elements involved in the biomineralization process vary with age throughout life depending on deer species, sex and hard tissues. CONCLUSION: Allowing for possible inferences of differential changes in the mineralization state at the main stages in life history, our methodological approach opens up new possibilities in zooarchaeological, paleontological, and wildlife research.


Asunto(s)
Densidad Ósea , Ciervos/fisiología , Mandíbula/fisiología , Minerales/análisis , Diente/fisiología , Animales , Estudios Transversales , Masculino , Región Mediterránea
11.
J Am Dent Assoc ; 152(2): 146-156, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33358237

RESUMEN

BACKGROUND: The authors of this practice-based study estimated the risk of experiencing tooth fractures and crack progression over 3 years and correlated baseline patient-, tooth-, and crack-level characteristics with these outcomes. METHODS: Two-hundred-and-nine National Dental Practice-Based Research Network dentists enrolled a convenience sample of 2,601 participants with a cracked vital posterior tooth that had been examined for at least 1 recall visit over 3 years. Data were collected at the patient, tooth, and crack levels at baseline, annual follow-up visits, and any interim visits. Associations between these characteristics and the subsequent same-tooth fractures and crack progression were quantified. RESULTS: Of the 2,601 teeth with a crack or cracks at baseline, 78 (3.0%; 95% confidence interval, 2.4% to 3.7%) subsequently developed a fracture. Of the 1,889 patients untreated before year 1, 232 (12.3%; 95% confidence interval, 10.9% to 13.8%) had some type of crack progression. Baseline tooth-level characteristics associated with tooth fracture were the tooth was maxillary and had a wear facet through enamel and a crack was detectable with an explorer, on the facial surface, and in a horizontal direction. Crack progression was associated with males and teeth with multiple cracks at baseline; teeth with a baseline facial crack were less likely to show crack progression. There was no commonality between characteristics associated with tooth fracture and those associated with crack progression. CONCLUSIONS: Development of tooth fractures and crack progression over 3 years were rare occurrences. Specific characteristics were associated with the development of tooth fracture and crack progression, although none were common to both. PRACTICAL IMPLICATIONS: This information can aid dentists in assessing factors that place posterior cracked teeth at risk of experiencing adverse outcomes.


Asunto(s)
Síndrome de Diente Fisurado , Fracturas de los Dientes , Diente , Esmalte Dental , Humanos , Masculino , Fracturas de los Dientes/epidemiología , Fracturas de los Dientes/etiología
12.
J Endod ; 47(3): 366-373, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33359534

RESUMEN

INTRODUCTION: The objective of this case-control study was to investigate the association between denosumab use and the risk of developing external cervical resorption (ECR). METHODS: Thirty-three patients ≥45 years old who were diagnosed with ECR were selected. Controls were matched to the cases based on sex and age (±5 years) in a 1:1 ratio. Confounders were classified into systemic factors, including a history of systemic sclerosis, hepatitis B, denosumab use, and bisphosphonate use, or local factors, including a history of traumatic occlusion, periodontal procedures (scaling and root planing and periodontal surgeries), and tooth extraction (excluding third molar extraction). Additionally, the number of remaining teeth in each subject was recorded using panoramic radiographs. The baseline characteristics of the 2 groups, including age, sex, and the number of remaining teeth, were compared using the chi-square and Mann-Whitney U tests. Binary logistic regression was used to determine the possible association between denosumab use and the risk of developing ECR (α < 0.05). RESULTS: No significant differences in baseline characteristics were observed between the case and control groups (P > .05). After adjusting for systemic and local cofounders, denosumab use was significantly associated with the occurrence of ECR (odds ratio = 7.317; 95% confidence interval, 1.410-37.966; P < .05). CONCLUSIONS: Based on the binary logistic regression model, denosumab use could significantly predict the risk of developing ECR.


Asunto(s)
Resorción Radicular , Diente , Estudios de Casos y Controles , Preescolar , Denosumab/efectos adversos , Humanos , Persona de Mediana Edad , Cuello del Diente
13.
PLoS One ; 15(12): e0229370, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33326416

RESUMEN

The present study applies a dental morphological perspective to the understanding of the complex pre-contact population history of the South Central Andes, through the detection of the underlying dynamics, and the assessment of the biological ties among groups. It presents an analysis of 1591 individuals from 66 sites that date from the Archaic to the Late Intermediate phases from Bolivia, Chile and Peru. The results suggest this area is characterized by significant movement of people and cultures and, at the same time, by long standing population continuity, and highlight the need for wider perspectives capable of taking into account both the different micro-regional realities and the region in its entirety.


Asunto(s)
Migración Humana/historia , Dinámica Poblacional/historia , Arqueología , Bolivia , Chile , Femenino , Fósiles , Historia Antigua , Humanos , Indios Sudamericanos , Masculino , Perú , Diente
14.
Head Face Med ; 16(1): 37, 2020 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-33323128

RESUMEN

BACKGROUND: The aim of the study was to compare a 2D and 3D color system concerning a variety of statistical and graphical methods to assess validity and reliability of color measurements, and provide guidance on when to use which system and how to interpret color distance measures, including ΔE and d(0M1). METHODS: The color of teeth 14 to 24 of 35 patients undergoing regular bleaching treatment was visually assessed and electronically measured with the spectrophotometer Shade Inspector™. Tooth color was recorded before bleaching treatment, after 14 days, and again after 6 months. VITAPAN® Classical (2D) and VITA-3D-Master® (3D) served as reference systems. RESULTS: Concerning repeated measurements, the 2D system was superior to the 3D system, both visually and electronically in terms of ΔE and d(OM1), for statistics of agreement and reliability. All four methods showed strong patterns in Bland-Altman plots. In the 3D system, hue was less reliable than lightness and chroma, which was more pronounced visually than electronically. The smallest detectable color difference varied among the four methods used, and was most favorable in the electronic 2D system. Comparing the methods, the agreement between the 2D and 3D system in terms of ΔE was not good. The reliability of the visual and electronic method was essentially the same in the 2D and 3D systems; this comparability is fair to good. CLINICAL RELEVANCE: The 3D system may confuse human raters and even electronic devices. The 2D system is the simple and best choice.


Asunto(s)
Diseño de Prótesis Dental , Diente , Color , Electrónica , Humanos , Reproducibilidad de los Resultados , Espectrofotometría
15.
J Dent Hyg ; 94(6): 25-32, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33376119

RESUMEN

Purpose: The purpose of this study was to determine whether the adjunctive use of an experimental calculus disruption solution (EXP-955), combined with the exclusive use of hand instruments, decreases the amount of time required to remove supragingival dental calculus deposits.Methods: A single-site, randomized, split-mouth clinical trial was conducted to compare the time needed to remove supragingival dental calculus on deposits pretreated with an experimental calculus disruption solution vs. calculus deposits that were not pretreated. Quadrants were randomized to either the treatment or control group and the principal investigator (PI) was timed while using hand instruments to remove the calculus. At the end of each session, both the subjects and the PI completed a questionnaire assessing their perceptions regarding the various aspects of the appointment and the solution. Descriptive statistics were used to analyze the data. Recurring themes from the questionnaire were examined.Results: Twenty-five healthy subjects, each having two quadrants matched for number of teeth and level of calculus deposits, completed the study (n=25). A statistically significant difference was found in in the supragingival calculus removal times between the control, (M=12.5 minutes; SD=6.0), and the treatment, (M=9.7; SD=4.6), quadrants; Mean difference (95% CI) = 2.8 (1.8-3.7), p<0.0001. Thematic analysis of the questionnaire responses showed that the perceptions of the principal investigator and subjects were positive towards the use of the solution with less pain being a common participant comment. The experimental calculus disruption solution was well tolerated by all subjects.Conclusions: Results from this proof of concept study provide preliminary evidence that use of an experimental calculus disruption solution (EXP-955) reduced the time needed to remove supragingival calculus while using hand instrumentation.


Asunto(s)
Cálculos Dentales , Diente , Cálculos Dentales/terapia , Atención Odontológica , Humanos , Prueba de Estudio Conceptual
16.
Biol Lett ; 16(12): 20200750, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33321067

RESUMEN

Theropod dinosaurs are well known for having a ziphodont dentition: serrated, blade-shaped teeth that they used for cutting through prey. Serrations along the carinae of theropod teeth are composed of true denticles, a complex arrangement of dentine, enamel, and interdental folds. This structure would have supported individual denticles and dissipated the stresses associated with feeding. These particular serrations were previously thought to be unique to theropod dinosaurs and some other archosaurs. Here, we identify the same denticles and interdental folds forming the cutting edges in the teeth of a Permian gorgonopsian synapsid, extending the temporal and phylogenetic distribution of this dental morphology. This remarkable instance of convergence not only represents the earliest record of this adaptation to hypercarnivory but also demonstrates that the first iteration of this feature appeared in non-mammalian synapsids. Comparisons of tooth serrations in gorgonopsians with those of earlier synapsids and hypercarnivorous mammals reveal some gorgonopsians acquired a complex tissue arrangement that differed from other synapsids.


Asunto(s)
Dinosaurios , Diente , Animales , Evolución Biológica , Dinosaurios/anatomía & histología , Fósiles , Mamíferos , Filogenia
17.
Angle Orthod ; 90(5): 680-687, 2020 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-33378488

RESUMEN

OBJECTIVES: To assess and compare spontaneous expansion of mandibular posterior teeth between tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME). MATERIALS AND METHODS: This study included 36 adolescents with bilateral maxillary crossbite receiving tooth-borne (average age: 14.4 ± 1.3 years) or bone-borne (average age: 14.7 ± 1.4 years) maxillary expansion. Cone beam computed tomography was acquired before expansion (T1) and after 6 months' retention (T2). Specific linear and angular measurements were performed in the coronal view to assess buccal inclinations and widths of mandibular posterior units. All data were statistically analyzed. RESULTS: In both groups there was a significant increase in buccal-lingual inclination of mandibular posterior teeth ranging from 1.67° to 2.30° in the TB group and from 1.46° to 2.11° in BB group. Mandibular posterior widths showed an increase ranging from 0.80 mm to 1.33 mm in TB group and from 0.64 mm to 0.96 mm in the BB group. No differences between groups were found for linear or angular measurements. CONCLUSIONS: A clinically significant gain of space in the mandibular arch should not be expected after RME.


Asunto(s)
Maloclusión , Diente , Adolescente , Tomografía Computarizada de Haz Cónico , Humanos , Maxilar/diagnóstico por imagen , Técnica de Expansión Palatina
18.
Angle Orthod ; 90(6): 811-822, 2020 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-33378522

RESUMEN

OBJECTIVES: To determine the different impact of moment-to-force ratio (M:F) variation for each tooth and spatial plane and to develop a mathematical model to predict the orthodontic movement for every tooth. MATERIALS AND METHODS: Two full sets of teeth were obtained combining cone-beam computed tomography (CBCT) and optical scans for two patients. Subsequently, a finite element analysis was performed for 510 different force systems for each tooth to evaluate the centers of rotation. RESULTS: The center of CROT locations were analyzed, showing that the M:F effect was related to the spatial plane on which the moment was applied, to the force direction, and to the tooth morphology. The tooth dimensions on each plane were mathematically used to derive their influence on the tooth movement. CONCLUSION: This study established the basis for an orthodontist to determine how the teeth move and their axes of resistance, depending on their morphology alone. The movement is controlled by a parameter (k), which depends on tooth dimensions and force system features. The k for a tooth can be calculated using a CBCT and a specific set of covariates.


Asunto(s)
Técnicas de Movimiento Dental , Diente , Tomografía Computarizada de Haz Cónico , Análisis de Elementos Finitos , Humanos , Fenómenos Mecánicos , Diente/diagnóstico por imagen , Raíz del Diente/diagnóstico por imagen
19.
Ann Biol Clin (Paris) ; 78(6): 593-603, 2020 Dec 01.
Artículo en Francés | MEDLINE | ID: mdl-33361014

RESUMEN

The use of dental stem cells has raised many hopes in the development of new treatments for neurodegenerative diseases. According to current statistics, about 1 in 6 people in the world would be affected by a neurological disease. This number continues to increase as the world's population ages, making neurodegenerative diseases probably the one of the major challenges of public health in the 21st century. Neurodegenerative diseases are characterized mainly by a progressive loss of cognitive abilities and patient autonomy related to loss and degeneration of neurons in brain structures. Unfortunately, today, the only treatments available for this type of disease do only relieve the symptoms, they do not treat them, and few clinical trials have been truly convincing to date. Hence, hope lies for these diseases in the development of other therapeutic approaches. As such, dental stem cells could be a promising area of research because of their rapid growth, their great capacity for differentiation into different types of cells (among neuronal ones for some of them) and how easy they can be obtained, without raising ethical issues as for example for embryonic stem cells.


Asunto(s)
Células-Madre Neurales/fisiología , Enfermedades Neurodegenerativas/terapia , Medicina Regenerativa/tendencias , Células Madre/fisiología , Diente/citología , Animales , Diferenciación Celular , Humanos , Regeneración Nerviosa/fisiología , Células-Madre Neurales/citología , Neurogénesis/fisiología , Medicina Regenerativa/métodos , Trasplante de Células Madre/métodos , Trasplante de Células Madre/tendencias , Células Madre/citología , Bancos de Tejidos/tendencias , Técnicas de Cultivo de Tejidos/métodos , Técnicas de Cultivo de Tejidos/tendencias
20.
PLoS One ; 15(12): e0243985, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33378326

RESUMEN

Sixteen specimens of the Early Triassic cynodont Galesaurus planiceps (including eight that were scanned using micro-computed tomography) representing different ontogenetic stages were assembled to study the dental replacement in the species. The growth series shows that the incisors and postcanines continue to develop and replace, even in the largest (presumably oldest) specimen. In contrast, replacement of the canines ceased with the attainment of skeletal maturity, at a basal skull length of ~90 mm, suggesting that Galesaurus had a finite number of canine replacement cycles. Additionally, the functional canine root morphology of these larger specimens showed a tendency to be open-rooted, a condition not previously reported in Mesozoic theriodonts. An alternating pattern of tooth replacement was documented in the maxillary and mandibular postcanine series. Both postcanine series increased in tooth number as the skull lengthened, with the mandibular postcanine series containing more teeth than the maxillary series. In the maxilla, the first postcanine is consistently the smallest tooth, showing a proportional reduction in size as skull length increased. The longer retention of a tooth in this first locus is a key difference between Galesaurus and Thrinaxodon, in which the mesial-most postcanines are lost after replacement. This difference has contributed to the lengthening of the postcanine series in Galesaurus, as teeth continued to be added to the distal end of the tooth row through ontogeny. Overall, there are considerable differences between Galesaurus and Thrinaxodon relating to the replacement and development of their teeth.


Asunto(s)
Dinosaurios/anatomía & histología , Fósiles/anatomía & histología , Diente/anatomía & histología , Animales , Dinosaurios/clasificación , Maxilar/anatomía & histología , Filogenia
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