Pulp caries affected versus endodontic treated and composite resin restored young permanent molars -bite force and specific finite element analysis

Endodontic treatment (ETT) followed by direct composite resin restoration has been used for rehabilitating the severely damage molar teeth in young patients. The aim of this study was to evaluate the effect of the molar teeth with different levels of the dental structure loss before and after the ETT and direct restoration with bulk fill resin composite on the stress distribution and the bite force magnitude. Three young patients (with 9, 10 and 12 years old), with the first mandibular molar teeth with deep occlusal caries with pulp involvement were selected attending with different levels of the dental structure loss: PI, both marginal ridge and all cusps; PII, maintenance of one marginal ridge and loss of one cusp; and PIII, loss of both marginal ridge, maintaining only buccal cusps. ETT was restored using Filtek Bulk Fill Posterior (3M ESPE). The bite forces in Newtons were measured initially and postoperatively for all teeth in habitual bite force using a miniload cell. Cone-beam tomography imaging was performed, and the Digital Imaging and Communication in Medice (.dcm) files were exported to Mimics, 3-Matic (Materialise) and Patran (MSC Software) software to create a patient-specific FEA models. Bite load was carry out using contact load applied by antagonist teeth in two moments: without ETT and restoration: PI. 30.1/136.6; PII. 34.3/133.4 and PIII. 47.9/124.1; and after restorative procedure: PI. 136.6; PII. 133.4 and PIII. 124.1 N. Performing ETT and bulk fill resin composite restoration the bite load increased 260% (36.7±11.6) to 131.9±17.8). The restorations were evaluated after 2 years. Before rehabilitation the stresses concentrated on weakened coronal dental structure and after rehabilitation they were homogeneously transferred to root dentin, irrespective of the level of the tooth structure loss. When the postoperatively bite load was applied on nontreated tooth models, high stress concentration on weakened areas was verified. The restorations performed perfectly after 2 years. The extensive caries with pulp involvement affected negatively the bite load and increased the stress concentration on weakened areas and at furcation favoring the tooth fracture. The ETT and bulk fill resin composite restoration showed to be an efficient method for rehabilitate the biomechanical performance of molar teeth of young patients severely compromised structurally.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorCNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas GeraisDissertação (Mestrado)O tratamento endodôntico associado à restauração direta com resina composta tem sido utilizado para restaurar molares severamente destruídos em pacientes jovens. O objetivo deste estudo foi avaliar o efeito de diferentes níveis de perda de estrutura dentária antes e após a realização de tratamento endodôntico e restauração com resina composta bulk fill na distribuição de tensões e magnitude da força de mordida. Foram selecionados três pacientes jovens (9, 10 and 12 anos de idade) com primeiros molares com cárie extensa e envolvimento pulpar com diferentes níveis de perdas de estrutura dentária: PI, manutenção das duas cristas marginais e de todas as cúspides; PII, manutenção de pelo menos uma crista marginal e perda mínima de uma cúspide; e PIII, perda de ambas as cristas marginais, mantendo apenas as cúspides vestibulares. Os molares foram tratados endodonticamente utilizando técnica de instrumentação rotatória e obturados com guta-percha e cimento AHPlus (Dentsply) e em seguida foram restaurados com Filtek Bulk Fill Posterior (3M ESPE). A força de mordida em Newtons (N) foi mensurada antes e após a intervenção endodôntica e restauradora na posição habitual de oclusal usando aparelho de força de mordida por meio de uma célula de carga (Kratos). Tomografias computadorizadas cone beam foram realizadas antes e após o procedimento endodôntico/restaurador, e arquivos DICOM (.dcm) foram exportados para o software Mimics, 3-Matic (Materialize) e Patran (MSC Software) para criação dos modelos específicos dos pacientes nos dois momentos experimentais. A aplicação de carga foi simulada por contato oclusal dos dentes antagonistas nas cargas mensuradas clinicamente em cada momento. Nos modelos que representam as condições iniciais foram aplicados tanto os valores de força de mordida (N) mensurados no momento inicial quanto após o procedimento reabilitador: PI. 30,1/136,6; PII. 34,3/133,4 e PIII. 47,9/124,1 e para os modelos que representam a condição final foram utilizados os valores obtidos após a intervenção endodôntica e restauradora: PI. 136,6; PII. 133,4 e PIII. 124,1. As restaurações foram avaliadas após 2 anos. Após intervenção endodôntica e restauradora a força de mordida aumentou em 260% (de 36,7±11,6 para 12 131,9±17,8). Antes da intervenção endodôntica e restauradora, as tensões se concentraram na estrutura coronal e, após a reabilitação foram transferidas de forma homogênea para a dentina radicular, independente do nível de perda de estrutura dentária. Quando a carga final foi aplicada nos modelos de condições iniciais, evidenciou-se elevada concentração de tensão em áreas enfraquecidas e na região de furca. As restaurações apresentaram desempenho adequado após 2 anos. A presença de cárie extensa com envolvimento pulpar afetou negativamente a carga de mordida e aumentou a concentração de tensão na estrutura frágil o que pode favorecer à ocorrência de fratura dental. O tratamento endodôntico associado à restauração direta em resina composta bulk fill demonstrou ser um método eficiente para restabelecer o desempenho mastigatório e a eficiência biomecânica dos molares jovens com comprometimento severo da estrutura coronária

Direct resin composite restoration of endodontically-treated permanent molars in adolescents: bite force and patient-specific finite element analysis

Objective: To evaluate the influence of three levels of dental structure loss on stress distribution and bite load in root canal-treated young molar teeth that were filled with bulk-fill resin composite, using finite element analysis (FEA) to predict clinical failure. Methodology: Three first mandibular molars with extensive caries lesions were selected in teenager patients. The habitual occlusion bite force was measured using gnathodynamometer before and after endodontic/restoration procedures. The recorded bite forces were used as input for patient-specific FEA models, generated from cone-beam computed tomographic (CT) scans of the teeth before and after treatment. Loads were simulated using the contact loading of the antagonist molars selected based on the CT scans and clinical evaluation. Pre and post treatment bite forces (N) in the 3 patients were 30.1/136.6, 34.3/133.4, and 47.9/124.1. Results: Bite force increased 260% (from 36.7±11.6 to 131.9±17.8 N) after endodontic and direct restoration. Before endodontic intervention, the stress concentration was located in coronal tooth structure; after rehabilitation, the stresses were located in root dentin, regardless of the level of tooth structure loss. The bite force used on molar teeth after pulp removal during endodontic treatment resulted in high stress concentrations in weakened tooth areas and at the furcation. Conclusion: Extensive caries negatively affected the bite force. After pulp removal and endodontic treatment, stress and strain concentrations were higher in the weakened dental structure. Root canal treatment associated with direct resin composite restorative procedure could restore the stress-strain conditions in permanent young molar teeth

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

Selective caries removal and glass ionomer liner reduce pulp stress of bulk-fill resin composite restoration

Dental caries in young molars progress rapidly, generating the need for restorative interventions in cavities involving dentin degradation. The removal of infected and caries-affected tissue is still controversial in the most appropriate strategy to be used. According to this context, the purpose of this study was to evaluate the effect of selective or total caries removal on molars affected by deep caries restored using bulk fill composite resin (Tetric N Ceram, Ivoclar Vivadent) with or without the use of a protective layer of the complex dentino-pulp with resin-modified glass ionomer cement, RMGIC (Vitrebond, 3M Oral Care) in the distribution of tension in the pulp chamber roof as a possible cause of pulp sensitivity. Finite element models were created from digital X-ray of the lower first molar characterizing the experimental groups: I. healthy tooth; II. tooth with deep caries; III. selective removal of infected dentin using a glass ionomer liner; IV. selective removal of infected dentin and without using a glass ionomer liner; V. non-selective removal of decayed dentin and using a glass ionomer liner; and VI. non-selective removal of decayed dentin and without using a glass ionomer liner. The dentin healthy elasticity module, affected and infected tooth decay was calculated using dynamic nanoindentation. The post-gel contraction of the bulk fill and RMGIC composite resin were determined using the extensometry method. The modified Von Mises tension (MPa) was extracted at the nodes of the inner wall of the pulp ceiling chamber after a restorative procedure and with a 100N occlusal load simulation. The data were analyzed qualitatively by images of stress distribution patterns and quantitatively by stress peaks along the pulp chamber roof. Both factors of the study influenced the stress concentration during the restorative procedure. The tension generated during the restorative procedure was higher for non-selective caries removal without using RMGIC (25.9 MPa) and lower for selective caries removal using RMGIC (13.5 MPa). Molar with deep caries showed high tension in the pulp roof (89.6 MPa) and in the weakened coronal structure. During the bite force simulation, the group with non-selective caries removal without using RMGIC presented higher modified von Mises tension values than the selective caries removal associated with the use of RMGIC. The selective removal of caries followed by the use of RMGIC reduced the sensibility on the pulp chamber roof after restoration and during the bite force. The pulp sensitivity observed in molar teeth affected by caries during the chewing process can also be explained by the high concentration of stresses in the roof of the pulp chamber. The selective removal of caries in molar teeth with deep caries, in addition to avoiding accidental pulp exposure, can also minimize the occurrence of pulp sensitivity after restoration with bulk fill composite resin, especially when associated with RMGIC.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTese (Doutorado)A cárie dental em molares jovens progride de forma acelerada gerando necessidade de intervenções restauradoras em cavidades que envolvem degradação da dentina. A remoção do tecido infectado e afetado pela cárie gera ainda controvérsia na estratégia mais adequada a ser utilizada. Frente a este contexto, o objetivo desse estudo foi avaliar o efeito da remoção seletiva ou total de tecido cariado em molares afetados por cárie profunda restaurados usando resina composta bulk fill (Tetric N Ceram, Ivoclar Vivadent) com ou sem o uso de camada protetora do complexo dentino-pulpar com cimento de ionômero de vidro modificado por resina, CIVMR (Vitrebond, 3M Oral Care) na distribuição de tensão no teto da câmara pulpar como possível causa de sensibilidade pulpar. Modelos de elementos finitos foram criados a partir de raio-X digital de primeiro molar inferior caracterizando os grupos experimentais: I. dente hígido (H); II.dente com cárie profunda (CP); III. remoção seletiva da dentina infectada e com uso de base de ionômero de vidro (RS-CIVMR); IV. remoção seletiva da dentina infectada e sem uso de base de ionômero de vidro (RS-SCIVMR); V. remoção não seletiva da dentina cariada e com uso de base de ionômero de vidro (RNSCIVMR); e VI. remoção não seletiva da dentina cariada e sem uso de base de ionômero de vidro (RNS-SCIVMR). O módulo de elasticidade da dentina hígida, afetada e infectada por cárie foi calculado usando nanoindentação dinâmica. A contração pós-gel da resina composta bulk fill e CIVMR foram determinadas usando o método de extensometria. A tensão de Von Mises modificado (MPa) foi extraída nos nós da parede interna da câmara do teto pulpar após procedimento restaurador e com simulação de carga oclusal de 100N. Os dados foram analisados qualitativamente por imagens de padrões de distinção de tensões e quantitativamente pelos picos de tensões ao longo do teto da câmara pulpar. Ambos os fatores do estudo influenciaram a concentração de tensão durante o procedimento restaurador. A tensão gerada durante o procedimento restaurador foi maior para remoção não seletiva de cárie sem uso de CIVMR (25,9 MPa) e menor quanto à remoção seletiva de cárie com uso de CIVMR (13,5 MPa). Molar com cárie profunda mostrou alta tensão no teto da polpa (89,6 MPa) e na estrutura coronal fragilizada. Durante a simulação da força de mordida o grupo com remoção não seletiva de cárie sem uso CIVMR apresentou valores de tensão de von Mises modificado mais elevados que a remoção seletiva de cárie associada ao uso de CIVMR. A remoção seletiva de cárie seguida pelo uso de CIVMR reduziu as tensões no teto da câmara pulpar após restauração e durante a força de mordida. A remoção seletiva de cárie em dentes molares com cárie profunda, além de evitar a exposição acidental da polpa, pode também minimizar a ocorrência de sensibilidade pulpar após a restauração com resina composta bulk fill, principalmente quando associada ao CIVMR.2022-09-1

Selective carious tissue removal and glass ionomer liner reduction of pulp stress in bulk fill resin composite restorations

Agência(s) de fomento: CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico; FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais e CAPES - Finance code 001 - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.Este estudo foi realizado no Centro de Pesquisa em Biomecânica, Biomateriais e Biologia Celular – CPBIO/FOUFU.Link para acesso ao trabalho: https://www.scielo.br/j/bor/a/cvLj4XkBRqfvtNzdSJSxfJh/?lang=enTo evaluate the effect of selective or nonselective carious tissue removal and the use of a resin-modified glass ionomer (RMGIC) liner under bulk fill resin composite restoration on the stress at the pulp chamber, the elastic moduli of hard, firm, soft and intact dentin were calculated using nanoindentation. Post-gel shrinkage of the bulk fill resin composite and RMGIC were determined using the strain- gauge method. Six finite element models were created by using digital radiography with the combination of two study factors: a) carious tissue removal: selective removal or nonselective removal of carious tissue, and b) use of RMGIC liner: with or without 1.0 mm of RMGIC liner. The modified von Mises stresses (mvm) (MPa) were extracted on the nodes of the internal wall of the pulp ceiling chamber at 100 N occlusal loading. Data were analyzed descriptively and recorded quantitively. Both study factors influenced the stress distribution. The mvm stress during the restorative procedure was higher for nonselective carious tissue removal without RMGIC (25.9 MPa) and lower for selective carious tissue removal associated with RMGIC (13.5 MPa). The dentin elastic modulus increased from soft carious (3.6 0.3 MPa) to firm carious (5.2 1.0 MPa) to hard carious (10.9 1.2 MPa) to intact dentin (22.7 3.0 MPa). Molars with carious lesions showed high mvm stress at the pulp ceiling (89.6 MPa) and at fragilized coronal structure remaining. Selective carious tissue removal followed by restoration using a Vitrebond liner and Tetric N-Ceram Bulk fill reduced the stress at the pulp chamber ceiling.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoTrabalho de Conclusão de Curso (Graduação)Avaliar o efeito da remoção seletiva ou não seletiva de tecido cariado e o uso de proteção com ionômero de vidro modificado por resina (RMGIC) sob restauração de resina composta bulk fill na distribuição de tensões no teto da câmara pulpar. O módulo de elasticicidade da dentina rígida, consistente, amolecida e intacta foram calculados usando nanoindentação. A contração pós-gel da resina composta bulk fill e RMGIC foram determinadas utilizando o método de extensometria. Seis modelos de elementos finitos foram criados usando uma radiografia digital com a combinação de dois fatores de estudo: a) remoção de tecido cariado: remoção seletiva ou não seletiva de tecido cariado, e b) uso de proteção RMGIC: com ou sem proteção de 1,0 mm de RMGIC. As tensões de von Mises modificadas (mvm) (MPa) foram extraídas nos nós da parede interna da câmara do teto pulpar com carga oclusal de 100 N. Os dados foram analisados descritivamente e registrados quantitativamente. Ambos os fatores do estudo influenciaram a distribuição de tensão. A tensão mvm durante o procedimento restaurador foi maior para remoção não seletiva de tecido cariado sem RMGIC (25,9 MPa) e menor para remoção seletiva de tecido cariado associado ao RMGIC (13,5 MPa). O módulo de elasticidade da dentina aumentou de cárie amolecida (3,6 ± 0,3 MPa) para cárie consistente (5,2 ± 1,0 MPa) para cárie rígida (10,9 ± 1,2 MPa) e para dentina intacta (22,7 ± 3,0 MPa). Molares com lesões de cárie apresentaram alta tensão mvm no teto pulpar (89,6 MPa) e no restante da estrutura coronária fragilizada. A remoção seletiva de tecido cariado seguida da restauração usando proteção com Vitrebond e Tetric N-Ceram Bulk fill reduziu a tensão no teto da câmara pulpar.2024-07-1

Polymerization shrinkage stress of composite resins and resin cements – What do we need to know?

Abstract Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed

How biomechanics can affect the endodontic treated teeth and their restorative procedures?

Abstract: Endodontic treatment is a common dental procedure used for treating teeth which the pulp tissue has become irreversibly inflamed or necrotic as a result of the carious process or dental trauma. This procedure which involves mechanical and chemical preparation of root canal may affect several mechanical and physical properties of the tooth structure. The endodontic treatment can also influence the longevity of the rehabilitation of endodontically treated teeth and biomechanics during the oral function. For restoring endodontically treated teeth several factor and clinical decisions should be observed. The decision of the fiberglass post usage and the restorative materials are related to several factors such as the quantity and quality of remaining dental structure, presence of ferrule, post cementation length and final coronal restoration. In this review, the authors will address the effect of the endodontic treatment procedures on canal shape and mechanical properties of a tooth, and also discuss the parameters and the biomechanical principles of root canal treated teeth