Tensile stress distribution in maxillary central incisors restored with cast-made and prefabricated dental posts

To analyze and compare the tensile stress distribution in endodontically treated teeth restored with cast-made (Ni-Cr and gold) and prefabricated (titanium and glass fibre) dental posts. Methodology: Four threedimensional finite element (FE) models of a maxillary central incisor restored with Ni-Cr cast-made (Model Ni-Cr), gold cast-made (Model GO), prefabricated titanium (Model TI) and prefabricated glass fibre (Model FP) posts were constructed. An oblique loading of 100N was applied to each three-dimensional model. Tensile stress distribution within the root dentine and at the post and surrounding structure interfaces were analysed

Dental prostheses mimic the natural enamel behavior under functional loading: A review article

SummaryAlumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores), and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ) structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability

Functional Biomimetic Dental Restoration

Bioinspired functionally graded approach is an innovative material technology, which has rapidly progressed both in terms of materials processing and computational modeling in recent years. Bioinspired functionally graded structure allows the integration of dissimilar materials without formation of severe internal stress and combines diverse properties into a single material system. It is a remarkable example of nature’s ability to engineer functionally graded dental prostheses. Therefore, this novel technology is designed to improve the performance of the materials in medical and dental fields. Thus, this chapter book reviews the current status of the functionally graded dental prostheses and biomimetic process inspired by the human bone, enamel and dentin-enamel junction (DEJ) structures and the linear gradation in Young’s modulus of the human bone, enamel and dentin-enamel junction, as a new material design approach, to improve the performance compared to traditional dental prostheses. Notable research is highlighted regarding application of biomimetic prostheses into various fields in dentistry. The current chapter book will open a new avenue for recent researches aimed at the further development of new dental prostheses for improving their clinical durability

Niveles de percepción y confianza entre estudiantes de odontología y pasantes en la realización de diversos procedimientos de endodoncia.

Aim: The present study aimed to collect information from senior students and new interns enrolled at the College of Dentistry, University of Science and Technology (UST), regarding their confidence levels in performing endodontic treatments. Materials and Methods: Anonymous surveys were distributed to 40 senior students and 37 new interns at UST, in Sana'a, Yemen. They were asked to indicate their self-confidence level using a Likert scoring system ranging from 1 and 5. Mann-Whitney U test and chi-squared test were used to determine statistical significance between the studied groups. Results: 37.5% of students and 35.1% of interns rated endodontic practice as difficult. Only 55% of students found that the number of treated cases were satisfactory, similar to that reported by interns (56.8%). There were no statistically significant differences between both groups regarding self-confidence levels for most endodontic procedures (p<0.05). Placing of a rubber dam, followed by managing inter-appointment flare-ups were procedures in which both groups reported the lowest confidence. On the other hand, both groups felt the lowest confidence in the treatment of maxillary followed by mandibular molars. Statistically significant differences were reported between the two groups for performing root canal treatments (RCT) (p< 0.05). Self-confidence levels on the management of most different indications showed no statistically significant differences between both groups (p>0.05) with exception to the management of irreversible pulpitis, necrotic pulp, asymptomatic apical periodontitis, chronic abscess, and traumatic cases, in which significant differences were noticed (p<0.05). Immature apices, root resorption, endodontic-periodontal (EP) lesions, trauma, symptomatic apical periodontitis and acute abscess were ranked as the cases in which both groups reported the lowest confidence. Canal blockage and ledge formation were the main mishaps encountered during practice among students and interns. Conclusion: Students and interns displayed neutral confidence in performing endodontic treatments.Objetivo: El presente estudio tuvo como objetivo recopilar información de estudiantes de último año y nuevos pasantes inscritos en la Facultad de Odontología, Universidad de Ciencia y Tecnología (UST), con respecto a sus niveles de confianza en la realización de tratamientos de endodoncia. Materiales y métodos: se distribuyeron encuestas anónimas a 40 estudiantes de último año y 37 nuevos pasantes en UST, en Sana'a, Yemen. Se les pidió que indicaran su nivel de confianza en sí mismos utilizando un sistema de puntuación Likert que oscilaba entre 1 y 5. Se utilizaron la prueba U de Mann-Whitney y la prueba de ji al cuadrado para determinar la significación estadística entre los grupos estudiados. Resultados: el 37.5% de los estudiantes y el 35.1% de los pasantes calificaron la práctica de endodoncia como difícil. Solo el 55% de los estudiantes encontró que el número de casos tratados fue satisfactorio, similar al reportado por los pasantes (56.8%). No hubo diferencias estadísticamente significativas entre ambos grupos con respecto a los niveles de autoconfianza para la mayoría de los procedimientos de endodoncia (p<0.05). La colocación de una presa de goma, seguida de la gestión de brotes entre citas, fueron procedimientos en los que ambos grupos informaron la menor confianza. Por otro lado, ambos grupos sintieron la menor confianza en el tratamiento del maxilar seguido de los molares mandibulares. Se informaron diferencias estadísticamente significativas entre los dos grupos para realizar tratamientos de conducto radicular (ECA) (p<0.05). Los niveles de autoconfianza en el manejo de la mayoría de las indicaciones diferentes no mostraron diferencias estadísticamente significativas entre ambos grupos (p>0.05) con excepción del manejo de pulpitis irreversible, pulpa necrótica, periodontitis apical asintomática, absceso crónico y casos traumáticos, en los cuales se notaron diferencias (p<0.05). Los ápices inmaduros, la reabsorción radicular, las lesiones endodóncicas-periodontales (EP), los traumatismos, la periodontitis apical sintomática y el absceso agudo se clasificaron como los casos en que ambos grupos informaron la menor confianza. El bloqueo del canal y la formación de repisas fueron los principales percances encontrados durante la práctica entre estudiantes y pasantes. Conclusión: los estudiantes y los pasantes mostraron una confianza neutral en la realización de tratamientos de endodoncia

Tensile stress distribution in maxillary central incisors restored with cast-made and prefabricated dental posts.

Abstract: Aim: To analyze and compare the tensile stress distribution in endodontically treated teeth restored with cast-made (Ni-Cr and gold) and prefabricated (titanium and glass fibre) dental posts. Methodology: Four three-dimensional finite element (FE) models of a maxillary central incisor restored with Ni-Cr cast-made (Model Ni-Cr), gold cast-made (Model GO), prefabricated titanium (Model TI) and prefabricated glass fibre (Model FP) posts were constructed. An oblique loading of 100N was applied to each three-dimensional model. Tensile stress distribution within the root dentine and at the post and surrounding structure interfaces were analysed. Results: In all the FE models studied, a higher magnitude of tensile stresses was observed on the palatal aspect of the cervical dentin as compared to the labial aspect and progressively decreases from the outer to the inner part of the root. The gold cast-made and glass fibre post models showed significantly less tensile stress concentration in the post-core component than the other experimental models. The maximum tensile stress was seen on the palatal aspect of the Ni-Cr compared to other posts. The higher magnitude interfacial tensile stress concentration was observed in a pulpless tooth restored with a Ni-Cr cast-made post, followed by titanium and gold cast-made posts, respectively. However, the minimum interfacial tensile stress was noticed in a pulpless tooth restored with a glass fibre post. Conclusion: Glass fibre posts tend to transfer tensile stress more homogenously within the tooth and at interfaces than the other types of investigated posts

External and Internal Anatomy of Mandibular Permanent Incisors

A clear understanding of dental root anatomy, external and internal, is an essential prerequisite to all dental procedures. In periodontology, the external root morphology has been proven to have a clinical significance in the predisposing factors of periodontal diseases. Orthodontic literature shows the importance of radicular anatomy in orthodontic mechanics through the concept of anchorage. The significance of internal root anatomy has been emphasized by studies demonstrating that variations in canal geometry before cleaning, shaping, and obturation procedures had a greater effect on the outcome than the techniques themselves. The mandibular central incisor is the smallest tooth in the mouth, but the buccolingual dimension of its root is very large. This tooth is usually single-rooted; however, the root canal system of this group is unpredictable. The incidence of two canals has been reported as low as 0.3% and as high as 45.3%. The wide range of variation reported in literature regarding the prevalence of a second canal has been related to methodological and racial differences. This chapter will summarize the morphological aspects of the root canal anatomy published in the literature of the anterior mandibular teeth. This will provide precious knowledge regarding root canal morphology and its variation among populations

External and Internal Anatomy of Maxillary Permanent First Molars

Adequate knowledge of the tooth morphology is of paramount importance for clinicians worked in the different branches of dentistry in order to maintain good oral health. Unfortunately, tooth morphology shows a high level of complexity and variability. These anatomical variations have been reported to be related to many factors including age, gender and ethnicity. The permanent first molars are the largest teeth in the maxilla which play an important role in mastication. Because of their early eruption, they are more vulnerable to caries and subsequent pulp and periapical pathoses. This chapter will summarize the internal and external morphologic features of these teeth with the reported variations in relation to age, gender and population in order to provide clinicians with the morphological knowledge necessary for performing successful dental treatments

Assessment of the prevalence of radix entomolaris and distolingual canal in mandibular first molars in 15 countries: a multinational cross-sectional study with meta-analysis

Aim: The aim of this study was two-folded: i) to assess the prevalence of Distolingual Canal (DLC) and Radix Entomolaris (RE) in Mandibular First Molars (M1Ms), using Cone Beam Computed Tomography (CBCT) images and ii) to assess the impact of sociodemographic factors on the prevalence of these conditions worldwide. Methods: CBCT images were scanned retrospectively and the ones including bilateral M1Ms were included in the study. The evaluation was performed by 1 researcher in each country, trained with CBCT technology. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating axial sections from coronal to apical. The presence of DLC and RE in M1Ms (yes/no) was identified and recorded. Results: Six thousand three hundred four CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries regarding the prevalence of both RE and DLC (P .05). Conclusion: The overall prevalence of RE and DLC in M1Ms was 3% and 22%. Additionally, both RE and DLC showed substantial bilaterally. These variations should be considered by endodontic clinicians during endodontic procedures in order to avoid potential complications

Application of Calcium Phosphate Materials in Dentistry

Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields