Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 19.145
Filtrar
1.
Braz. j. oral sci ; 21: e222812, jan.-dez. 2022. tab
Artículo en Inglés | LILACS, BBO - Odontología | ID: biblio-1348712

RESUMEN

Aim: To evaluate the influence of the parameters L* a* b* on the variation of the color of bovine tooth enamel submitted to artificial darkening, after simulated brushing, with whitening toothpastes containing blue covarine. Methods: To undertake this study in vitro, 60 specimens (SP) were divided into 6 groups (n=10): control group (CGwater) and 5 test groups (GT1-Colgate Total 12, GT2-Oral-B 3D White Perfection, GT3- Colgate Luminous Instant White, GT4-CloseUp White Diamond Attraction, GT5-Sorriso Xtreme White). The specimens were darkened with coffee and submitted to simulated brushing for 6, 12, and 24 months. The alteration in the color was evaluated using CIELAB parameters and the ΔL, Δa, Δb and ΔE were calculated. The data was analyzed through generalized linear models using the R program and considering a level of significance of 5%. Results: The parameters L*, a* and the ΔL, Δa obtained better results in the test group than in the control group. There were no statistical differences between CG and the test groups for the evaluation of the b* parameter. In the evaluation of the Δb, the GT3 differed statistically from the CG. In relation to the ΔE, all the group tests showed a variation in color statistically greater than that of the CG and the GT4 showed the greatest variation, not differing from the GT3 during the periods studied. Conclusion: The mechanical and optical whitening agents positively influenced the values L*a* and b*, as well as in its variations and in the ΔE. It is important to emphasize, however, that to analyze tooth whitening it is necessary to evaluate their parameters together


Asunto(s)
Diente , Pastas de Dientes , Color , Blanqueadores
2.
Homo ; 73(1): 77-92, 2022 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-36353971

RESUMEN

Dental macrowear is the non-pathological loss of hard tissues on the occlusal surface of the teeth. In archaeological contexts, the loss of tooth tissues is often correlated with lifestyles, habits, and with the physical properties of the consumed food - including preparation techniques. We report the first semiquantitative and quantitative assessment on dentine exposure of permanent second molars (M2) using the scale scoring technique, image analysis, and regression analysis on human teeth from Chalcolithic and Bronze Age archaeological populations discovered in North-Eastern Romania. We show an increase of dentine exposure percent (PDE) with the age-ranges, but no evidence of wear by sex were observed. In the linear regression analysis, the age and the dentine exposure percent, as variables, were correlated in 31% of the mandibular M2 molars and 49% in the maxillary ones (p < 0.001). Moreover, the multiple regression analysis involving the dentine exposure and the three variables that could influence the dental wear (i.e., age, occlusal area, and period) revealed no differences in dental wear between Chalcolithic and Bronze Age, as well as between different cultures of Bronze Age (i.e., Monteoru Culture and Noua Culture). Therefore, apart from age, occlusal area, and period, there may be other factors including diet and food-processing techniques that could be also considered when discussing the loss of tooth tissues in archaeological populations, especially farmers.


Asunto(s)
Desgaste de los Dientes , Diente , Humanos , Rumanía , Dieta , Diente/patología , Desgaste de los Dientes/patología , Diente Molar
3.
BMC Oral Health ; 22(1): 480, 2022 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-36352390

RESUMEN

BACKGROUND: The aim of this study was to develop artificial intelligence (AI) guided framework to recognize tooth numbers in panoramic and intraoral radiographs (periapical and bitewing) without prior domain knowledge and arrange the intraoral radiographs into a full mouth series (FMS) arrangement template. This model can be integrated with different diseases diagnosis models, such as periodontitis or caries, to facilitate clinical examinations and diagnoses. METHODS: The framework utilized image segmentation models to generate the masks of bone area, tooth, and cementoenamel junction (CEJ) lines from intraoral radiographs. These masks were used to detect and extract teeth bounding boxes utilizing several image analysis methods. Then, individual teeth were matched with a patient's panoramic images (if available) or tooth repositories for assigning tooth numbers using the multi-scale matching strategy. This framework was tested on 1240 intraoral radiographs different from the training and internal validation cohort to avoid data snooping. Besides, a web interface was designed to generate a report for different dental abnormalities with tooth numbers to evaluate this framework's practicality in clinical settings. RESULTS: The proposed method achieved the following precision and recall via panoramic view: 0.96 and 0.96 (via panoramic view) and 0.87 and 0.87 (via repository match) by handling tooth shape variation and outperforming other state-of-the-art methods. Additionally, the proposed framework could accurately arrange a set of intraoral radiographs into an FMS arrangement template based on positions and tooth numbers with an accuracy of 95% for periapical images and 90% for bitewing images. The accuracy of this framework was also 94% in the images with missing teeth and 89% with restorations. CONCLUSIONS: The proposed tooth numbering model is robust and self-contained and can also be integrated with other dental diagnosis modules, such as alveolar bone assessment and caries detection. This artificial intelligence-based tooth detection and tooth number assignment in dental radiographs will help dentists with enhanced communication, documentation, and treatment planning accurately. In addition, the proposed framework can correctly specify detailed diagnostic information associated with a single tooth without human intervention.


Asunto(s)
Caries Dental , Periodontitis , Diente , Humanos , Radiografía Panorámica , Inteligencia Artificial , Caries Dental/diagnóstico por imagen
4.
Artículo en Inglés | MEDLINE | ID: mdl-36360780

RESUMEN

The main objective of this paper is to perform an updated literature review of guided endodontics based on the available up-to-date scientific literature to identify and describe the technique, its benefits, and its limitations. Four electronic databases (PubMed, Scopus, Science Direct, and Web of Science) were used to perform a literature search from 1 January 2017 to 13 May 2022. After discarding duplicates, out of 1047 results, a total of 29 articles were eligible for review. Guided endodontics is a novel technique that is currently evolving. It is applied in multiple treatments, especially in accessing and locating root canals in teeth with pulp canal obliteration, microsurgical endodontics, and removing glass fiber posts in endodontic retreatments. In addition, it is independent of an operator's experience, requires less treatment time for the patient, and is more accurate and safer than conventional endodontics.


Asunto(s)
Endodoncia , Diente , Humanos , Tratamiento del Conducto Radicular , Atención Odontológica , Cavidad Pulpar
5.
BMC Oral Health ; 22(1): 468, 2022 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-36335341

RESUMEN

BACKGROUND: The association between dental anomalies has been studied, giving rise to the concept of Dental Anomaly Pattern (DAP). Tooth agenesis has been associated with alterations such as molar infracclusion, taurodontism and delayed dental development. The aim of this study was to evaluate the dental development pattern in patients with non-syndromic dental agenesis, in comparison with a control group. METHODS: Dental and chronological age was analysed in a sample size of 204 orthopantomographs divided into a study group (n = 104) and a control group (n = 100) with the Demirjian Method. Intra and intergroup differences in chronological and dental age, and the correlation between them were calculated by statistical analysis with a 95% confidence level (p < 0.05). RESULTS: Dental age exceeded chronological age both in the control group and in the study group. Statistically significant differences (p = 0.004) were found when comparing the difference between chronological and dental age in the study (-0.16 ± 1.12) and control group (-0.58 ± 0.90). Regarding sex and age intergroup differences, the results were only statistically significant in the girls' group (p = 0.017), and the age over 8 years old (p < 0.05). There were no significant differences in tooth development depending on the number of missing teeth or the affected tooth group, but there was a delay in the development of the homologous tooth contralateral to the absent one in 14.9% of patients. CONCLUSIONS: The difference between chronological and dental age in permanent dentition is significantly lower in Spanish children with non-syndromic agenesis compared to a control group, presenting a lower dental age than chronological age than children without non-syndromic agenesis.


Asunto(s)
Anodoncia , Anomalías Dentarias , Diente , Niño , Femenino , Humanos , Anodoncia/diagnóstico por imagen , Anodoncia/epidemiología , Dentición Permanente , Radiografía Panorámica , Anomalías Dentarias/diagnóstico por imagen , Anomalías Dentarias/epidemiología , Odontología Pediátrica
6.
Int J Mol Sci ; 23(21)2022 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-36361687

RESUMEN

Teeth have proven to be a reliable source of DNA for forensic analysis as the pulp is rich in cells and protected from damaging factors and contamination by dental hard tissues. The pilot study aims to evaluate the feasibility of Next-Generation sequencing analysis on dental pulp to detect genetic mutations in DNA caused by post-mortem cell necrosis. We used a 56-gene oncopanel kit on a sample of 17 teeth extracted from living patients. Time of the tooth avulsion was assumed as death of the individual and Post-mortem Interval (PMI) was the time elapse since the DNA extraction and analysis. Days and Accumulated Degree Days (ADD) were assumed as measures of PMI that ranged between 0 to 34 days. Only 38 of the 56 considered genes proved to be affected by mutations (101), thus being of forensic interest. More specifically, 14 mutations occurred only in a specific range of PMIs/ADD; 67 were detected (alone or as clusters of the same gene) at specific PMI/ADD; 22 occurred at every PMI/ADD, except for some specific intervals. Since dental pulp was not targeted by any oncological diseases and all teeth were intact, vital, and from patients with unremarkable medical history, it could be assumed that mutations were due to post-mortem DNA changes induced by pulp death and the increasing time elapse since death. This pilot study found encouraging results in the application of NGS analysis on dental DNA, especially for PMIs of several days for which the traditional tools for PMI estimation have limitations. Further research on a larger sample of PMI and validation research on a larger sample of PMI and validation of the results are indeed necessary.


Asunto(s)
Cambios Post Mortem , Diente , Humanos , Proyectos Piloto , Autopsia , ADN
7.
BMC Oral Health ; 22(1): 472, 2022 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-36335336

RESUMEN

BACKGROUND: Occlusal force represents masticatory function. Using quantifiable occlusal indicators provides a more objective occlusal force evaluation. In the recent dental practice, digital methods such as the Dental Prescale II (DP2, GC Corp., Tokyo, Japan) and T-scan (T-Scan III v8; Tekscan Inc.) are commonly used in clinics to evaluate treatment outcomes. The T-scan provides the relative bite force (%) compared to the maximal bite force on individual teeth or the unilateral arch. The DP2 can quantify occlusal force, measured in newtons (N), on the half arch or the overall bite, but it is difficult to identify the bite force on an individual tooth. It is difficult to select a device that fulfils all the requirements to record occlusal force. This study aimed to investigate the association between the bite measured by the DPS2 and T-scan to determine whether the measured bite force is comparable through calculation. METHODS: A total of 80 healthy adults, including 41 women and 39 men with a mean age of 38.2, were requested to bite pressure sensitive film sheets ten minutes apart. Linear regression analysis was used to estimate the measured bite force by the DP2 and T-scan. RESULTS: There was a significant positive correlation between the occlusal force measured by the DP2 and T-scan (P < 0.01) when intercept was equal to zero as confounders were adjused. These results provided the comparability of the measured occlusal forces determined by the DP2 and T-scan. CONCLUSION: The estimated bite force determined by DP2 and T-Scan is convertible using the linear equation from this study to increase the value for clinical applications. The estimated bite force from the two quantifiable occlusal indicators are comparable. The two commercially available quantifiable occlusal indicators can be fully adapted to all clinical requirements according to this result.


Asunto(s)
Fuerza de la Mordida , Diente , Masculino , Adulto , Femenino , Humanos , Oclusión Dental , Modelos Lineales , Japón
8.
Expert Opin Biol Ther ; 22(11): 1405-1416, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36345819

RESUMEN

INTRODUCTION: Over the last two decades, an increasing body of research suggests that well-designed biomaterials can attract resident stem cells to injured areas and control their behaviors and activities to encourage tissue regeneration. Fabricated biomaterials can enhance cell recruitment, multiplication, and transformation while also acting as a delivery system for targeted cells. These capabilities might play a role in their ability to promote tooth regeneration. AREAS COVERED: This review aims to introduce the various materials used in endodontics. The potential of biomaterial-based approaches involved in cell homing for endodontics is also discussed. EXPERT OPINION: Applying the cell homing technique in restorative dentistry can affect various aspects of healthcare, industry, economy, and science. Biomaterial scaffolds can be used to encapsulate cells or for structural replacements. Also, both cell transplantation and cell homing are legitimate scientific procedures in endodontic therapy. Although the suggested biomaterials and procedures may hold promise for future dental pulp tissue regeneration, tooth structure's complexity and multicellular interconnections lead to significant problems that need to be overcome before any clinical trial.


Asunto(s)
Materiales Biocompatibles , Diente , Humanos , Ingeniería de Tejidos/métodos , Células Madre , Dentina
9.
Sci Rep ; 12(1): 19809, 2022 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-36396696

RESUMEN

Deep learning allows automatic segmentation of teeth on cone beam computed tomography (CBCT). However, the segmentation performance of deep learning varies among different training strategies. Our aim was to propose a 3.5D U-Net to improve the performance of the U-Net in segmenting teeth on CBCT. This study retrospectively enrolled 24 patients who received CBCT. Five U-Nets, including 2Da U-Net, 2Dc U-Net, 2Ds U-Net, 2.5Da U-Net, 3D U-Net, were trained to segment the teeth. Four additional U-Nets, including 2.5Dv U-Net, 3.5Dv5 U-Net, 3.5Dv4 U-Net, and 3.5Dv3 U-Net, were obtained using majority voting. Mathematical morphology operations including erosion and dilation (E&D) were applied to remove diminutive noise speckles. Segmentation performance was evaluated by fourfold cross validation using Dice similarity coefficient (DSC), accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV). Kruskal-Wallis test with post hoc analysis using Bonferroni correction was used for group comparison. P < 0.05 was considered statistically significant. Performance of U-Nets significantly varies among different training strategies for teeth segmentation on CBCT (P < 0.05). The 3.5Dv5 U-Net and 2.5Dv U-Net showed DSC and PPV significantly higher than any of five originally trained U-Nets (all P < 0.05). E&D significantly improved the DSC, accuracy, specificity, and PPV (all P < 0.005). The 3.5Dv5 U-Net achieved highest DSC and accuracy among all U-Nets. The segmentation performance of the U-Net can be improved by majority voting and E&D. Overall speaking, the 3.5Dv5 U-Net achieved the best segmentation performance among all U-Nets.


Asunto(s)
Aprendizaje Profundo , Diente , Humanos , Estudios Retrospectivos , Tomografía Computarizada de Haz Cónico , Diente/diagnóstico por imagen , Cabeza
10.
Genes (Basel) ; 13(11)2022 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-36360314

RESUMEN

The site of Zhengzhou Shang City (ca. 1509-1315 cal. BC) was the capital of the early Shang Dynasty in China. Archaeological excavations have unearthed a ditch containing approximately one hundred unusual dead human skulls in the rammed-earth foundations of the palace area. The identity and origin of the skulls have long been disputed. In this work, strontium, carbon and nitrogen stable isotope analyses were carried out on 11 human skulls and 1 tooth from the ditch, as well as on 11 human bones, 11 human teeth from the ordinary tombs and 10 pig teeth from the Zhengzhou Shang City site. We determined that, in Zhengzhou Shang City, the local strontium isotope ratio ranges from 0.711606 to 0.711884, and ordinary inhabitants consumed mainly C4 plants supplemented by C3 plants. Moreover, humans buried in the ditch have 87Sr/86Sr values from 0.711335 to 0.711741 and consumed only C4 plants. Combining the isotopic data with the archaeological and cultural context, it is concluded that the unusual human skulls in the ditch are most likely those of prisoners of war captured by the central forces conquering the Xiaomintun area of Anyang in the early Shang Dynasty. The results provide valuable insight into the history of violence and military warfare in the early Chinese dynasty.


Asunto(s)
Personal Militar , Diente , Humanos , Porcinos , Animales , Isótopos , Arqueología , Cráneo
11.
Medicina (Kaunas) ; 58(11)2022 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-36363473

RESUMEN

Background and Objectives: The purpose of this study is to observe the usefulness of autogenous tooth transplantation by examining the cumulative survival rate according to the period of auto-transplanted teeth as pre-implant treatment. Materials and Methods: This study was conducted on 111 patients who visited Kyungpook National University Dental Hospital and underwent autogenous tooth transplantation between November 2008 and January 2021 (about 13 years). The cumulative survival rate of autogenous tooth transplantation according to the causes of extraction of the recipient tooth (caries, periapical lesion, crack, crown fracture, periodontitis) and condition of opposing teeth (natural teeth vs. fixed prosthesis). The cumulative survival rate of autogenous tooth transplantation according to the age (under 30 vs. over 30) was also investigated and it was examined whether there were any differences in each factor. Results: The average follow-up period was 12 months, followed by a maximum of 162 months. The 24-month cumulative survival rate of all auto-transplanted teeth was 91.7%, 83.1% at 60 months and the 162-month cumulative survival rate was 30.1%. There were no statistical differences between the causes of extraction of the recipient's teeth, differences in the condition of the opposing teeth, and differences under and over the age of 30. Conclusions: The survival rate of autogenous tooth transplantation appears to be influenced by the conditions of the donor tooth rather than the conditions of the recipient tooth. Although autogenous tooth transplantation cannot completely replace implant treatment, it is meaningful in that it can slightly delay or at least earn the time until implant placement is possible.


Asunto(s)
Fracturas de los Dientes , Diente , Humanos , Tasa de Supervivencia , Diente/trasplante , Trasplante Autólogo , Extracción Dental , Estudios de Seguimiento , Resultado del Tratamiento
13.
Naturwissenschaften ; 109(6): 52, 2022 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-36322292

RESUMEN

The radula, a chitinous membrane spiked with teeth, is the molluscan autapomorphy for the gathering and processing of food. The teeth, as actual interfaces between the organism and the ingesta, act as load transmitting regions and have to withstand high stresses during foraging - without structural failure or high degrees of wear. Mechanisms contributing to this were studied previously in paludomid gastropods from Lake Tanganyika. For some species, gradients in hardness and Young's modulus along the teeth were detected, enabling the bending and relying of teeth onto the next row, distributing the stresses more equally. The here presented study on one of them - Lavigeria grandis - aims at shedding light on the origin of these functional gradients. The mechanical properties were identified by nanoindentation technique and compared to the elemental composition, determined by elemental dispersive X-ray spectroscopy (EDX, EDS). This was done for the complete radular (mature and immature tooth rows), resulting in overall 236 EDX and 700 nanoindentation measurements. Even though teeth showed regional differences in elemental composition, we could not correlate the mechanical gradients with the elemental proportions. By applying confocal laser scanning microscopy (CLSM), we were finally able to relate the mechanical properties with the degree of tanning. CLSM is a common technique used on arthropod cuticle, but was never applied on radular teeth before. In general, we found that nanoindentation and CLSM techniques complement one another, as for example, CLSM is capable of revealing heterogeneities in material or micro-gradients, which leads to a better understanding of the functionalities of biological materials and structures.


Asunto(s)
Gastrópodos , Diente , Animales , Dureza , Módulo de Elasticidad
14.
Proc Biol Sci ; 289(1982): 20221132, 2022 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-36300520

RESUMEN

Traits for prey acquisition form the phenotypic interface of predator-prey interactions. In venomous predators, morphological variation in venom delivery apparatus like fangs and stingers may be optimized for dispatching prey. Here, we determine how a single dimension of venom injection systems evolves in response to variation in the size, climatic conditions and dietary ecology of viperid snakes. We measured fang length in more than 1900 museum specimens representing 199 viper species (55% of recognized species). We find both phylogenetic signal and within-clade variation in relative fang length across vipers suggesting both general taxonomic trends and potential adaptive divergence in fang length. We recover positive evolutionary allometry and little static allometry in fang length. Proportionally longer fangs have evolved in larger species, which may facilitate venom injection in more voluminous prey. Finally, we leverage climatic and diet data to assess the global correlates of fang length. We find that models of fang length evolution are improved through the inclusion of both temperature and diet, particularly the extent to which diets are mammal-heavy diets. These findings demonstrate how adaptive variation can emerge among components of complex prey capture systems.


Asunto(s)
Diente , Viperidae , Animales , Filogenia , Diente/anatomía & histología , Viperidae/anatomía & histología , Ponzoñas , Dieta , Mamíferos
15.
J Proteome Res ; 21(11): 2736-2742, 2022 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-36287021

RESUMEN

The radula is a unique foraging organ to Mollusca, which is important for their evolution and taxonomic classification. Many radulae are mineralized with metals. Although the remarkable mechanical properties of mineralized radulae are well-studied, the formation of mineralization from nonmineralized radulae is poorly understood. Taking advantage of the recently sequenced octopus and chiton genomes, we were able to identify more species-specific radular proteins by proteomics. Comparing these proteomes with the known limpet radula proteome enabled us to gain insight into the molecular components of nonmineralized and mineralized radula, highlighting that iron mineralization in the chiton radula is possibly due to the evolution of ferritins and peroxiredoxins. Through an in vitro binding assay, ferritin is shown to be important to iron accumulation into the nonmineralized radula. Moreover, radular proteomes reflect their adaption to dietary habits to some extent. The octopus radula has many scaffold modification proteins to suit flexibility while the chiton radula has abundant sugar metabolism proteins (e.g., glycosyl hydrolases) to adapt to algae feeding. This study provides a foundation for the understanding of molluscan radula formation and evolution and may inspire the synthesis of iron nanomaterials.


Asunto(s)
Proteómica , Diente , Animales , Hierro/metabolismo , Proteoma/genética , Proteoma/metabolismo , Moluscos/genética , Moluscos/química , Moluscos/metabolismo
16.
Arch Oral Biol ; 144: 105553, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36182707

RESUMEN

OBJECTIVE: This systematic review examines the effect of age on changes to coronal dentin properties. DESIGN: Pubmed, Cinhal, Scopus, Web of Science and the Cochrane Database were searched for publications up to 31 December 2021. All studies were uploaded and reviewed using Covidence software. At different stages of the review, study selection and the extraction of data were completed by six independent reviewers based on the eligibility criteria. The quality of the articles was judged based on JBI Critical Appraisal Checklist for quasi-experimental studies. RESULTS: Twelve studies satisfied the eligibility criteria and were included. Dentin characteristics and mechanical properties alter with age, and spatially within a tooth to depend on tubule orientation. Age-related mineral deposition within tubules, and collagen maturation in intertubular dentin compound the spatial effects on mechanical properties. Mechanical properties depend on collagen fiber orientation and apatite alignment relative to dentin tubules, characteristic differences in peritubular and intertubular dentin, and relative dentin tubule distribution within a tooth. The bulk of the research focussed on age-related apatite effects, although many reported limited understanding of changes to collagen, particularly in intertubular dentin. CONCLUSION: Investigations into the effect of age, depth, site and location on dentin collagen are warranted to minimize tooth loss in older populations by providing targeted adhesive, restorative or preventative interventions.


Asunto(s)
Dentina , Diente , Adulto , Humanos , Anciano , Colágeno , Apatitas , Minerales
17.
PLoS One ; 17(10): e0276198, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36264869

RESUMEN

Although placing a vent hole on the occlusal surface of the implant crown can reduce cervical marginal cement extrusion, it has disadvantages. Transferring the hole to the buccal or lingual surface of the posterior implant crown could therefore be an alternative solution. This study investigated the effect of transferring the vent hole to the lateral side of the implant posterior crown on the hydrodynamics of excess cement extrusion and the crown's retention ability. Specially fabricated posterior implant crowns were divided into five groups: crowns with an occlusal hole (OH), occlusal lateral hole (OLH), middle lateral hole (MLH), cervical lateral hole (CLH), and no hole (NH). Each set of implant analog-abutment-crown specimens was wrapped in a polymethylacrylate base. The base of the implant crown was divided into four 90-degree quadrants along the diagonal of the square base with a pen mark. Cement was used to bond the crowns and the abutments, and the weight of cement extrusions at the vent holes and the abutment cervical margins were calculated. The distribution of cement extrusion at the margin was photographed in each quadrant, and the areas of surface coverage of cement extrusion were compared with ImageJ software. Retentive strength was measured as the dislocation force using a universal testing machine. One-way analysis of variance was used for result analysis. The cervical marginal cement extrusions of crowns with lateral holes (OLH, MLH, and CLH) were significantly less than that of NH crowns (P<0.05), but more than that of OH crowns (P<0.05). Subgroup analysis among the lateral hole groups indicated that the higher the position of the lateral hole, the lower the weight of the cement extrusion, and the smaller the total distribution area of cement extrusion. The cement extrusion distribution area was larger in the quadrant with the hole than in those opposite and next to the hole. Retention strength comparison indicated no significant difference between crowns with NH, OH, or lateral holes. Transferring the vent hole of the posterior implant crown to the lateral side could reduce cement extrusion at the cervical margin while reducing retention strength deterioration and the esthetic drawbacks caused by occlusal hole opening.


Asunto(s)
Hidrodinámica , Diente , Coronas , Cementos de Ionómero Vítreo , Cementos para Huesos , Cementos Dentales , Pilares Dentales , Ensayo de Materiales , Cementación
18.
Leg Med (Tokyo) ; 59: 102148, 2022 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-36223694

RESUMEN

INTRODUCTION: Although the dental age assessment is commonly applied in forensic and maturity evaluation, the long-standing dilemma from population differences has limited its application. OBJECTIVES: This study aimed to verify the efficacy of the machine learning (ML) to build up the dental age standard of a local population. METHODS: We retrospectively studied 2052 panoramic films retrieved from healthy Taiwanese children aged 2.6-17.7 years with comparable sizes in each age-group. The recently reported Han population-based standard (H method) served as the control condition. To develop and validate ML models, random divisions of the sample in an 80%-20% ratio repeated 20 times. The model performances were compared with the H method, Demirjian's method, and Willems's method. RESULTS: The ML-assisted models provided more accurate age prediction than those non-ML-assisted methods. The range of errors was effectively reduced to less than one per year in the ML models. Furthermore, the consistent agreements among the age groups from preschool to adolescence were reported for the first time. The Gaussian process regression was the best ML model; of the non-ML modalities, the H method was the most efficacious, followed by the Demirjian's method and Willems's methods. CONCLUSION: The ML-assisted dental age assessment is helpful to provide customized standards to a local population with more accurate estimations in preschool and adolescent age groups than do studied conventional methods. In addition, the earlier complete tooth developments were also observed in present study. To construct more reliable dental maturity models in the future, additional environment-related factors should be taken into account.


Asunto(s)
Determinación de la Edad por los Dientes , Diente , Niño , Adolescente , Preescolar , Humanos , Determinación de la Edad por los Dientes/métodos , Radiografía Panorámica , Estudios Retrospectivos , Asiáticos , Aprendizaje Automático
19.
Artículo en Inglés | MEDLINE | ID: mdl-36232005

RESUMEN

Estimation of children's chronological age is highly important in human and forensic sciences. The Demirjian method has been reported as accurate for this purpose. The literature review shows some evidence that the accuracy of estimating chronological age via the Demirjian standards is not a straightforward process. The objective of this research is to analyze the reliability of the Demirjian standards in Portuguese and Spanish children and adolescents and adapt it to include sex and group age as contingent factors. METHODS: Orthopantomographs of 574 Portuguese and Spanish male and female children and adolescents were employed to test the reliability of the Demirjian method. After testing for inter-rater consistency and age estimation using the Demirjian standards, multiple regression analysis was performed controlling for sex and age group. RESULTS: The Demirjian standards overestimated chronological age for both sexes, mainly for females. Through the development of regression functions, more detailed dental age estimation was performed. The predictive capacities of the Demirjian method and the significant teeth varied as a function of children's age. The Demirjian global standard predicted over 65% of the variance of the chronological age. Taking a tooth-by-tooth approach, the predictive ability increased by over 70%. CONCLUSIONS: The accuracy of estimating chronological age via the Demirjian method is not as reliable as it might appear, judging from the results found according to age group and according to sex crossed with age group.


Asunto(s)
Determinación de la Edad por los Dientes , Diente , Adolescente , Determinación de la Edad por los Dientes/métodos , Niño , Femenino , Humanos , Masculino , Portugal , Radiografía Panorámica/métodos , Reproducibilidad de los Resultados
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...