Near-infrared imaging in orthodontic intraoral scanners for early interproximal caries detection.

INTRODUCTION: Intraoral scanners commonly used in orthodontic offices now offer near-infrared imaging (NIRI) technology, advertised as a screening tool to identify interproximal caries. This study aimed to evaluate the reliability and validity of NIRI detection of interproximal carious lesions in a common intraoral scanner (iTero Element 5D; Align Technology, San Jose, Calif) with and without bitewing radiograph complement, compared with a microcomputed tomography (micro-CT) reference standard. METHODS: Extracted human posterior teeth (premolars and molars) were selected for early (noncavitated) interproximal carious lesions (n = 39) and sound control surfaces (n = 47). The teeth were scanned via micro-CT for evaluation by 2 blinded evaluators using consensus scoring. The teeth were mounted to simulate anatomic interproximal contacts and underwent a NIRI scan using iTero Element 5D and bitewing radiographs. Two trained, calibrated examiners independently evaluated (1) near-infrared images alone with clinical photograph, (2) bitewing radiograph alone with clinical photograph, and (3) near-infrared images with bitewing radiograph and clinical photograph in combination, after at least a 10-day washout period between each evaluation. RESULTS: Interrater reliability was highest for NIRI alone (k = 0.533) compared with bitewing radiograph alone (k = 0.176) or in combination (k = 0.256). NIRI alone showed high specificity (0.83-0.96) and moderate sensitivity (0.42-0.63) compared with a micro-CT reference standard. Dentin lesions were significantly more reliably detected than enamel lesions. CONCLUSIONS: After rigorous training and calibration, NIRI can be used with moderate reliability, high specificity, and moderate sensitivity to detect noncavitated interproximal carious lesions.

Microcomputed Tomography Mineral Density Profile as Reference Standard for Early Carious Lesion Activity Assessment.

Early caries diagnosis is crucial to treatment decisions in dentistry and requires identification of lesion activity: whether a carious lesion is active (progressively demineralizing) or arrested (progressively remineralizing). This study aimed to identify microtomographic (micro-CT) differences between active and arrested smooth surface enamel lesions, to quantify those micro-CT differences by creating thresholds for ex vivo caries activity assessment to serve as a future reference standard, and to validate those thresholds against the remaining sample. Extracted human permanent teeth (n = 59) were selected for sound surfaces and non-cavitated smooth surface carious lesions. Each surface was then examined for caries activity by calibrated individuals via visual-tactile examination using the International Caries Classification and Management System (ICCMS) activity criteria. Each tooth was scanned via micro-CT and the mineral density was plotted against lesion depth. The area under the curve (AUC) was calculated and represented the loss of density for the outermost 96 µm of enamel. AUC thresholds obtained from micro-CT were established to classify sound, remineralized, and demineralized surfaces against the gold standard examiner's lesion assessment of sound, inactive, and active lesions, respectively. The established AUC thresholds demonstrated moderate agreement with the assessment in identifying demineralized lesions (k = 0.45), with high sensitivity (0.73) and specificity (0.77). This study demonstrated quantifiable differences among demineralized lesions, remineralized lesions, and sound surfaces, which contributes to the establishment of micro-CT as a reference standard for caries activity that may be used to improve clinical and laboratorial dental caries evaluations.

The natural CAD/CAM anterior implant single tooth restoration: A novel digital workflow.

OBJECTIVE: To report a novel digital workflow to replace an anterior maxillary tooth lost due to trauma with an implant multilayer restoration by using the patient's extracted tooth as a final crown restoration using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. CLINICAL CONSIDERATIONS: Instead of using the patient's natural tooth as an immediate provisional restoration to achieve predictable results in terms of esthetics and soft tissue structure, a novel digital strategy was performed to obtain a natural final crown restoration by using the patient's tooth associated with a lithium disilicate customized implant abutment. CONCLUSIONS: The perspective of using this strategic approach for implant restorative dental treatments in patients with traumatic root fractures in the anterior region has great potential as it helps to maintain the emergence profile of the natural dentition and esthetics. CLINICAL SIGNIFICANCE: Optimal esthetic outcomes are challenging in implant dentistry regarding soft tissue structure and morphology factors. Using natural teeth from surgery to deliver the final restoration might be beneficial when an anterior tooth is lost due to trauma.

Métodos de detecção de cárie / Methods of caries detection

A Odontologia contemporânea não deve restringir-se a identificar cavidades, mas, também, despertar para um diagnóstico precoce das lesões cariosas iniciais. Os mais diversos e modernos métodos de detecção de cárie vêm sendo desenvolvidos com objetivo de tornar mais preciso o diagnóstico de cárie dental. Os métodos de detecção mais utilizados são os convencionais, porém a associação dos métodos proporciona melhores resultados ao exame clínico tradicional isolado. Este estudo teve como propósito a revisão de literatura sobre os métodos de detecção da doença cárie disponíveis atualmente, baseados nos métodos radiográficos, fluorescência a laser e corrente elétrica.

The contemporary Odontology cannot be restricted to just identify cavities, but must be interested in an early diagnosis of caries lesions. Varied and modern methods of caries detection are being developed, aiming to turn the diagnosis of dental caries more accurate. The conventional methods are most used for detection, however, the association of methods offer better results to the clinician. The purpose of this paper was to do a literature review and to compare the methods of caries detection, based on radiographic methods, laser fluorescence and electric chain.

Topographical evaluation of different glass and quartz fiber post surface treatments by a tridimensional surface roughness test.

A tridimensional surface roughness test evaluation is a nondestructive method that can be used to perform a topographic analysis of different surface treatments for glass and quartz fiber posts. This study divided 75 fiber posts into three groups according to their manufacturer. Each group was divided into five subgroups (n = 5), according to the surface treatment each received: immersion in hydrofluoric acid, sandblasting, immersion in hydrogen peroxide, sandblasting followed by immersion in hydrofluoric acid, or sandblasting followed by immersion in hydrogen peroxide. Surface roughness was measured using a tridimensional surface roughness test and analyzed with three-dimensional analysis software. Results were statistically analyzed using Student's t-test. The only surface treatment to modify the surface topography of glass and quartz fiber posts and provide a significant increase in roughness was sandblasting airborne-particle abrasion with 50 micro alumina at a distance of 30 mm, using 2.5 bars of pressure for five seconds.

Three-dimensional stress distribution in the human periodontal ligament in masticatory, parafunctional, and trauma loads: finite element analysis.

BACKGROUND: The presence of the periodontal ligament (PDL) makes it possible to absorb and distribute loads produced during masticatory function and other tooth contacts into the alveolar process via the alveolar bone proper. However, several factors affect the integrity of periodontal structures causing the destruction of the connective matrix and cells, the loss of fibrous attachment, and the resorption of alveolar bone. METHODS: The purpose of this study was to evaluate the stress distribution by finite element analysis in a PDL in three-dimensional models of the upper central incisor under three different load conditions: 100 N occlusal loading at 45 degrees (model 1: masticatory load); 500 N at the incisal edge at 45 degrees (model 2: parafunctional habit); and 800 N at the buccal surface at 90 degrees (model 3: trauma case). The models were built from computed tomography scans. RESULTS: The stress distribution was quite different among the models. The most significant values (harmful) of tensile and compressive stresses were observed in models 2 and 3, with similarly distinct patterns of stress distributions along the PDL. Tensile stresses were observed along the internal and external aspects of the PDL, mostly at the cervical and middle thirds. CONCLUSIONS: The stress generation in these models may affect the integrity of periodontal structures. A better understanding of the biomechanical behavior of the PDL under physiologic and traumatic loading conditions might enhance the understanding of the biologic reaction of the PDL in health and disease.

Stress distribution in the cervical region of an upper central incisor in a 3D finite element model.

The aim of this study was to evaluate the stress distribution in the cervical region of a sound upper central incisor in two clinical situations, standard and maximum masticatory forces, by means of a 3D model with the highest possible level of fidelity to the anatomic dimensions. Two models with 331,887 linear tetrahedral elements that represent a sound upper central incisor with periodontal ligament, cortical and trabecular bones were loaded at 45 masculine in relation to the tooth's long axis. All structures were considered to be homogeneous and isotropic, with the exception of the enamel (anisotropic). A standard masticatory force (100 N) was simulated on one of the models, while on the other one a maximum masticatory force was simulated (235.9 N). The software used were: PATRAN for pre- and post-processing and Nastran for processing. In the cementoenamel junction area, tensile forces reached 14.7 MPa in the 100 N model, and 40.2 MPa in the 235.9 N model, exceeding the enamel's tensile strength (16.7 MPa). The fact that the stress concentration in the amelodentinal junction exceeded the enamel's tensile strength under simulated conditions of maximum masticatory force suggests the possibility of the occurrence of non-carious cervical lesions such as abfractions.

Stress distribution in the cervical region of an upper central incisor in a 3D finite element model

The aim of this study was to evaluate the stress distribution in the cervical region of a sound upper central incisor in two clinical situations, standard and maximum masticatory forces, by means of a 3D model with the highest possible level of fidelity to the anatomic dimensions. Two models with 331,887 linear tetrahedral elements that represent a sound upper central incisor with periodontal ligament, cortical and trabecular bones were loaded at 45º in relation to the tooth's long axis. All structures were considered to be homogeneous and isotropic, with the exception of the enamel (anisotropic). A standard masticatory force (100 N) was simulated on one of the models, while on the other one a maximum masticatory force was simulated (235.9 N). The software used were: PATRAN for pre- and post-processing and Nastran for processing. In the cementoenamel junction area, tensile forces reached 14.7 MPa in the 100 N model, and 40.2 MPa in the 235.9 N model, exceeding the enamel's tensile strength (16.7 MPa). The fact that the stress concentration in the amelodentinal junction exceeded the enamel's tensile strength under simulated conditions of maximum masticatory force suggests the possibility of the occurrence of non-carious cervical lesions such as abfractions.

Análise quantitativa in vitro da obturação de canais laterais / Quantitative in vitro analysis of the filling of lateral canals

O objetivo deste trabalho foi analisar a capacidade de penetração de guta-percha e cimento nos canais laterais simulados em blocos de resina acrílica realizados com o auxílio de uma microbiota cilíndrica de 0,2 mm de diâmetro. Os canais foram obturados utilizando duas técnicas de obturação: técnica de compactação vertical de Schilder modificada utilizando o Sistema Obtura II e técnica híbrida de Tagger. A técnica utilizando o Sistema Obtura II promoveu maior preechimento de guta-percha nos três terços, enquanto que a técnica híbrida de Tagger promoveu maior preenchimento de cimento nos canais laterais cervicais e mediais

Estudo das tensöes em prótese parcial fixa livre de metalalocerâmica - método dos elementos finitos / Stress study in a metal-free and metal-ceramic fixed partial denture - finite elements method

O objetivo desse estudo foi analisar a distribuiçäo de tensöes internas de von Mises, em uma prótese parcial fixa (PPF) de três elementos em metalocerâmica e em dois sistemas de cerâmica pura, através de carregamento estático aplicado em modelos matemáticos bidimensionais obtidos pelo método de elementos finitos. Em todos os modelos, foram utilizados retentores intra-radiculares fundidos (RIRF) em ouro. A partir da imagem impressa de uma peça anatômica de estudo, digitalizada diretamente em um "scanner", os desenhos foram confeccionados e suas imagens vetorizadas foram "exportadas" para o programa MSC/PATRAN 2000, onde foram realizados o pré e pós processamento, enquanto que a análise foi feita na ABAQUOS (HKS), utilizando-se um carregamento de 100N distribuídos em 17 pontos das superfícies oclusais dos modelos. Houve também a simulaçäo da ausência de contato interproximal no modelo de PPF em metalocêramica e em um dos sistemas de cerâmica pura. Os resultados mostraram que os dois sistemas cerâmicos para PPF avaliados se comportaram, sob o pono de vista mecânico e nas condiçöes impostas pela análise, satisfatoriamente em comparaçäo à metalocerâmica. Além disso, o estabelecimento de contato interproximal em modelos matemáticos avaliados pelo método de elementos finitos verdadeiros e confiáveis na análise