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.

Performance and efficacy of a recently introduced diamond rotary instrument: Cutting, surface preparation, and cleanability.

STATEMENT OF PROBLEM: Evaluation of the cutting efficiency and effectiveness, surface roughness, and cleanability of a novel rotary instrument is lacking. PURPOSE: The purpose of this in vitro study was to compare the cutting efficiency and effectiveness of a recently introduced diamond rotary instrument containing corundum microspheres with conventional instruments by evaluating the heat generated, surface roughness, and cleanability of each instrument after tooth preparations. MATERIAL AND METHODS: Sound molars (n=225) were used to evaluate cutting efficiency and effectiveness by measuring the heat generated by 3 diamond dental rotary instruments: test instrument (TI), reference instrument (RI), and NTI instrument (NI). Thirty cavity preparations (27 mm3) were prepared, and the thermal change (ΔT) was determined from a thermocouple inserted in the pulp chamber. The surface roughness of the dentin substrate was determined after veneer preparations using scanning white-light interferometry and scanning electron microscope imaging. The cleanability of TI and RI was also determined by comparing the efficacy of 3 conventional disinfection protocols after contaminating the instrument with Gram-positive or Gram-negative oral pathogens. The mean and standard deviation values for thermal change, surface roughness, and colony forming units were calculated at a 95% confidence level, and 1-way ANOVA was used to determine statistical significance (α=.05). RESULTS: The NI instrument had the lowest mean ΔT (1.47 °C). The TI (1.77 °C) and RI (1.85 °C) groups showed statistically similar means (P>.05). The TI presented the lowest surface roughness (1.68 µm), followed by the RI (1.87 µm) (P<.001). The NI resulted in the highest surface roughness (2.17 µm) (P<.001). The disinfection protocols used were more effective on the TI group than on the RI group regardless of organisms and time exposed to the cleaning solution (P<.001). CONCLUSIONS: The novel diamond instrument demonstrated similar cutting efficiency and effectiveness when compared with conventional diamond instruments. However, the novel instrument produced smoother tooth preparations and was easier to clean than the conventional diamond rotary instruments.

Influence of material and loading location on stress distribution of inlays.

PURPOSE: To evaluate the stress distribution of inlays fabricated with restorative materials of different elastic moduli under two functional loading conditions by using three-dimensional (3D) finite element analysis (FEA) models of a second maxillary premolar. METHODS: A 3D model of a sound maxillary left second premolar and its supporting bone was generated in a previous study and reutilized under permission of the authors for the present study. Inlay models obtained from the sound tooth were then assigned according to the type and inherent elastic modulus of the restorative material used, as follows: microhybrid composite (Filtek Z250); indirect resin composite (Paradigm); lithium disilicate reinforced glass ceramic (IPS e.max Press); and type III gold alloy. The geometric models were then exported for 3D FEA. All materials were considered isotropic, homogeneous, and linear-elastic. A static load of 100 N was applied in two conditions: axially at both cusps (axial loading) and at the mesial marginal ridge (proximal loading). Maximum principal and von Mises stresses were used to analyze the stress distribution pattern in inlays and sound premolar models. RESULTS: Under axial loading condition, either resin composite, ceramic or type III gold alloy inlays generated a similar biomechanical behavior, especially in terms of stress distribution in the remaining tooth structure and cusp deflection. However, higher tensile stresses were observed along the proximal gingival margin of the preparation under proximal loading in the Z250 and Paradigm models, as well as a greater cusp deflection. In contrast, a deflection like the sound model was observed in the ceramic and gold inlay models. CLINICAL SIGNIFICANCE: Restorative materials with higher elastic modulus, such as dental ceramics and type III gold alloys, seem to be the best choice for maxillary premolars restored with inlays in the presence of occlusal contact on the marginal ridge.

Influence of sonic application on surface roughness of bulk-fill resin composites.

PURPOSE: To evaluate the influence of sonic application on the surface roughness of bulk-fill resin composite restorations. METHODS: 80 intact bovine incisors had their incisal thirds removed, their buccal surfaces flattened, and standard preparations mimicking Class II preparations performed on their buccal surfaces. Specimens were then randomly assigned for restoration with the bulk-fill resin composites Tetric EvoCeram Bulk Fill, SureFil SDR flow+, and SonicFill 2, with sonic application for 15 seconds and 30 seconds as well as no sonic application. Filtek Supreme Ultra applied without sonic application served as control. Sonic application was accomplished with the KAVO SONICflex handpiece. Surface roughness was measured using a 3D scanner and data were analyzed using the Kruskal-Wallis and Mann-Whitney tests at a significance level of 0.05. RESULTS: No statistical differences were found between groups treated with and without sonic application. When materials were compared, Tetric EvoCeram Bulk Fill showed the lowest surface roughness in the 15-second sonic application subgroup; and SureFil SDR flow+ showed the highest surface roughness when applied without sonic application and in the 30-second sonic application subgroups. CLINICAL SIGNIFICANCE: Clinicians should expect a similar performance of bulk-fill resin composites in terms of surface roughness when applied with or without sonic activation. Precaution should be taken during the finishing/ polishing procedures of SureFil SDR flow+ resin composite.

Effect of finishing technique on the occurrence and length of microcracks in resin-based materials.

PURPOSE: To evaluate the presence and length of microcracks in resin-based materials finished with different techniques, using optical coherence tomography (OCT). METHODS: Standardized Class V preparations (3x2x2mm) were made in the facial and lingual surfaces of 20 recently-extracted human third molars. 20 preparations were restored with a resin-based composite material (RBC; Filtek Supreme Ultra) and the other 20 with a resin-modified glass-ionomer material (RMGI; Ketac Nano). After final polymerization, specimens were further stratified by finishing system: aluminum oxide discs (Sof-Lex) or spiral fluted carbide bur series (H48L). By random allocation, each extracted tooth therefore received one RBC and one RMGI restoration, and equal numbers of restorations from each material were finished using each finishing system (n= 10). After 24 hours of storage in 100% humidity at room temperature, the specimens were evaluated at x20 to x600 under environmental SEM. Cross-sectional occlusal-cervical B-mode images were obtained in increments of 25 mm from the mesial margin to the distal margin of the restoration using a spectral-domain (SD) OCT system and analyzed using Image J software to identify and measure microcrack penetration into each restoration. The total length (mm) at the point of the deepest microcrack penetration in each specimen was recorded. Data were statistically analyzed using a t-test. RESULTS: No microcracks were observed in the RBC samples. However, microcrack presence was identified in all of the RMGI specimens. The t-test showed a statistically significant difference (P< 0.05) in mean microcrack length values based on the finishing technique used for the RMGI samples. [SofLex: 0.67 (± 0.28) mm; carbide: 1.26 (± 0.30)] mm. Two-way ANOVA showed significant differences in the factors "finishing technique" and "restorative material" (P< 0.001). The interaction of these two factors was also statistically significant (P< 0.001). For the tested RMGI, Tukey post-hoc test revealed that the finishing with aluminum oxide groups resulted in statistically significant lower mean microcrack length when compared to spiral fluted carbide burs (P< 0.001). CLINICAL SIGNIFICANCE: Resin-modified glass-ionomer (RMGI) is more susceptible to microcrack presence than resin-based composites. Also, aluminum oxide discs produced lower values of mean microcrack length than spiral fluted carbide burs after the finishing procedure of RMGI restorations.

Influence of contact points on the performance of caries detection methods in approximal surfaces of primary molars: an in vivo study.

This in vivo study aimed to evaluate the influence of contact points on the approximal caries detection in primary molars, by comparing the performance of the DIAGNOdent pen and visual-tactile examination after tooth separation to bitewing radiography (BW). A total of 112 children were examined and 33 children were selected. In three periods (a, b, and c), 209 approximal surfaces were examined: (a) examiner 1 performed visual-tactile examination using the Nyvad criteria (EX1); examiner 2 used DIAGNOdent pen (LF1) and took BW; (b) 1 week later, after tooth separation, examiner 1 performed the second visual-tactile examination (EX2) and examiner 2 used DIAGNOdent again (LF2); (c) after tooth exfoliation, surfaces were directly examined using DIAGNOdent (LF3). Teeth were examined by computed microtomography as a reference standard. Analyses were based on diagnostic thresholds: D1: D 0 = health, D 1 ­D 4 = disease; D2: D 0 , D 1 = health, D 2 ­D 4 = disease; D3: D 0 ­D 2 = health, D 3 , D 4 = disease. At D1, the highest sensitivity/specificity were observed for EX1 (1.00)/LF3 (0.68), respectively. At D2, the highest sensitivity/ specificity were observed for LF3 (0.69)/BW (1.00), respectively. At D3, the highest sensitivity/specificity were observed for LF3 (0.78)/EX1, EX2 and BW (1.00). EX1 showed higher accuracy values than LF1, and EX2 showed similar values to LF2. We concluded that the visual-tactile examination showed better results in detecting sound surfaces and approximal caries lesions without tooth separation. However, the effectiveness of approximal caries lesion detection of both methods was increased by the absence of contact points. Therefore, regardless of the method of detection, orthodontic separating elastics should be used as a complementary tool for the diagnosis of approximal noncavitated lesions in primary molars.

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.

2D and 3D finite element analysis of central incisor generated by computerized tomography.

The purpose of this study was to compare the results of different hierarchical models in engineering analysis applied to dentistry with 2D and 3D models of a tooth and its supporting structures under 100 N occlusal loading at 45° and examine the reliability of simplified 2D models in dental research. Five models were built from computed-tomography scans: four 2D models with Plane Strain and Plane Stress State with linear triangular and quadratic quadrilateral elements and one 3D model. The finite element results indicated that the stress distribution was similar qualitatively in all models but the stress magnitude was quite different. It was concluded that 2D models are acceptable when investigating the biomechanical behavior of upper central incisor qualitatively. However, quantitative stress analysis is less reliable in 2D-finite element analysis, because 2D models overestimate the results and do not represent the complex anatomical configuration of dental structures. Therefore 3D finite element analyses of dental biomechanics cannot be simplified.

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.

Three dimensional finite element analyses of oral structures by computerized tomography.

Our aim was to document the benefits of three dimensional finite element model generations from computed tomography data as well as the realistic creation of all oral structures in a patient. The stresses resulting from the applied load in our study did not exceed the structure limitations, suggesting a clinically acceptable physiological condition.

Influência do material restaurador e da estrutura dental remanescente na distribuição de tensões em restaurações indiretas / The restorative material and remaining tooth influence on the strain distribution into indirect restorations

O presente estudo teve como objetivo analisar, por meio do método de elemetos finitos, a influência do preparo cavitário e do material restaurador na distribuição de tensões em restaurações do tipo inlay. Sete modelos matemáticos bidimensionais foram criados a partir de uma imagem digitalizada de um primeiro molar inferior. A análise foi feita no programa Abaqus (HKS), utilizando-se uma carga estátística de 300N distribuídas em três regiões das superfícies oclusais dos modelos. Os resultados mostraram que o compósito laboratorial (cerômero) foi o que apresentou a melhor distribuição de tensões, gerando um padrão homogêneo das mesmas.

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