Restauration des prémolaires dévitalisées sévèrement délabrées. L'influence de la longueur de l'extension pulpaire sur l'intégrité marginale et sur la résistance à la fatigue des endocrowns CAD-CAM en céramique de disilicate de lithium

Objectifs: Le but de cette étude a été d'évaluer la performance, en termes d'adaptation marginale et de résistance après fatigue, des prémolaires traitées endodontiquement et restaurées par des endocrowns. Méthodes: Quarante-huit prémolaires traitées endodontiquement ont été restaurées selon quatre groupes (n=12): overlays (Groupe A, pas d'extension pulpaire), endocrowns avec 2 mm d'extension pulpaire (Groupe B), endocrowns avec 4 mm d'extension pulpaire (Groupe C), et couronnes classiques (Groupe D). Les échantillons ont été soumis à un chargement thermomécanique cyclique. Les échantillons qui ont survécu ont été soumis à un chargement cyclique isométrique progressif jusqu'à la complétion de 105000 cycles ou la fracture de l'échantillon. Résultats: Aucune différence en pourcentage de marges fermées n'a été trouvée entre les endocrowns (Groupes B, C), et les couronnes (Groupe D). Conclusions: Les endocrowns avec une extension pulpaire de 2 mm et de 4 mm ont présenté des résultats après fatigue équivalents aux couronnes classiques

Restauration des prémolaires dévitalisées sévèrement délabrées. L'influence de la longueur de l'extension pulpaire sur l'intégrité marginale et sur la résistance à la fatigue des endocrowns CAD-CAM en céramique de disilicate de lithium

Objectifs: Le but de cette étude a été d'évaluer la performance, en termes d'adaptation marginale et de résistance après fatigue, des prémolaires traitées endodontiquement et restaurées par des endocrowns. Méthodes: Quarante-huit prémolaires traitées endodontiquement ont été restaurées selon quatre groupes (n=12): overlays (Groupe A, pas d'extension pulpaire), endocrowns avec 2 mm d'extension pulpaire (Groupe B), endocrowns avec 4 mm d'extension pulpaire (Groupe C), et couronnes classiques (Groupe D). Les échantillons ont été soumis à un chargement thermomécanique cyclique. Les échantillons qui ont survécu ont été soumis à un chargement cyclique isométrique progressif jusqu'à la complétion de 105000 cycles ou la fracture de l'échantillon. Résultats: Aucune différence en pourcentage de marges fermées n'a été trouvée entre les endocrowns (Groupes B, C), et les couronnes (Groupe D). Conclusions: Les endocrowns avec une extension pulpaire de 2 mm et de 4 mm ont présenté des résultats après fatigue équivalents aux couronnes classiques

Stress distribution difference between Lava Ultimate full crowns and IPS e.max CAD full crowns on a natural tooth and on tooth-shaped implant abutments

The goal of this short communication is to present finite element analysis comparison of the stress distribution between CAD/CAM full crowns made of Lava Ultimate and of IPS e.max CAD, adhesively luted to natural teeth and to implant abutments with the shape of natural teeth. Six 3D models were prepared using a 3D content-creating software, based on a micro-CT scan of a human mandibular molar. The geometry of the full crown and of the abutment was the same for all models representing Lava Ultimate full crowns (L) and IPS e.max CAD full crowns (E) on three different abutments: prepared natural tooth (n), titanium abutment (t) and zirconia abutment (z). A static load of 400 N was applied on the vestibular and lingual cusps, and fixtures were applied to the base of the models. After running the static linear analysis, the post-processing data we analyzed. The stress values at the interface between the crown and the abutment of the Lt and Lz groups were significantly higher than the stress values at the same interface of all the other models. The high stress concentration in the adhesive at the interface between the crown and the abutment of the Lava Ultimate group on implants might be one of the factors contributing to the reported debondings of crowns

Novel non-invasive reinforcement of MOD cavities on endodontically treated teeth

Objectives: To evaluate the biomechanical influence of reconnecting the buccal and lingual walls of endodontically treated lower molar with a large MOD cavity. Methods: 3D models were created from a micro-CT scan of an extracted intact lower human molar. Finite element analysis was then used to compare the stress distribution and displacement of the structures between different models: Unrestored MOD on ETT (Unrest), MOD on ETT restored with composite resin (Norm), MOD on ETT reinforced with a non-invasive ring (Ring) and intact tooth as the control (Int). Results: This study showed that the Unrest model presented the highest stress values at the cervical level. The non-invasive Ring model showed the lowest stress values at the cervical level, and the lowest deflection of the cusps. Conclusions: Mechanically reconnecting the remaining tooth structures has a direct positive effect on stress distribution and deformation of the remaining structures. Clinical relevance: Reinforcing ETT in a non-invasive direct approach is efficient in terms of preserving sound tooth structures, reducing the time of treatment and eliminating the laboratory steps required to create the restorations

3D Digital Smile Design With a Mobile Phone and Intraoral Optical Scanner

Extraoral facial scanning using a mobile phone has emerged as a viable, cost-effective option for certain applications not requiring high precision, such as patient education and 3-dimensional (3D) digital smile design. This technological development is particularly promising for general practitioners (GPs) who may not be able to invest in expensive,complex digital impressioning devices. This article describes and illustrates a relatively simple and accessible workflow that avails digital 3D facial scanning benefits to GPs

Evaluation of the validity of digital optical microscopy in the assessment of marginal adaptation of dental adhesive interfaces

Analysis of marginal adaptation of dental adhesive interfaces using scanning electron microscopy has proven to be a powerful nondestructive method to evaluate the quality of adhesion. This methodology is, however, time-consuming and needs expensive equipment. The purpose of this study was to evaluate the possibility and efficiency of using a digital optical microscope (DOM) to perform marginal analysis and to compare it with the scanning electron microscope (SEM) analysis. Fifteen defect-free molars were selected for this study. Class V cavities were prepared and restored with resin composite, and epoxy replicas were obtained from silicone impressions of the restored teeth. Custom-made image analysis software was then used to measure the percentage of the noncontinuous margins (NCM) of each sample. To compare the DOM to the gold standard, SEM, each sample was analyzed 10 times using the DOM and three times using the SEM, by the same experienced operator. The repeatability coefficient and concordance were evaluated, and a Bland and Altman analysis was used for comparison of the two methods of measurements. To validate the DOM analysis method, an ANOVA approach (Gage R R) was used. Repeatability and reproducibility, which are two components of precision to validate the DOM analysis system, were calculated. For this, the same restorations were analyzed by two additional operators three times with the DOM. The duration of each step of the analysis using both methods was also recorded as a secondary outcome. Regarding the repeatability of each method, the Friedman test showed no statistically significant difference within the repetitions of measurements by SEM and DOM (p= 0.523 andp= 0.123, respectively). Moreover, the Bland-Altman analysis revealed a bias of 0.86 and concluded no statistically significant difference between the two methods, DOM and SEM. ANOVA evaluated DOM measurement system variation including the variances of repeatability and reproducibility that represented, respectively, 0.3% and 4% of the variance components. Reproducibility or inter-operator variability represented the principal source of variability with a statistically significant difference (p= 0.024). The time required for analysis with SEM was almost double that of DOM. The use of digital optical microscopy appears to be a valid alternative to the SEM for the analysis of marginal adaptation of dental adhesive interfaces. Further studies to evaluate the effect of training of operators in digital optical microscopy could reveal higher accuracy for this method and inter-operator agreement when experience is gained

Color stability of different composite resins after polishing

The goals of the present study were to evaluate, in vitro, the staining of different composite resins submitted to different common beverages, and to compare the staining effect of each of these solutions. A total of 288 specimens were randomly divided into six groups and immersed for 4 weeks in five staining solutions represented by red wine, orange juice, coke, tea and coffee or in artificial saliva as a control group. When analyzed over a black background, mean ΔE00 values varied from 0.8 for Venus Diamond, Saremco Microhybrid and ELS in saliva and Estelite Posterior in coke to 37.6 for Filtek Supreme in red wine. When analyzed over a white background, mean ΔE00 values varied from 0.5 for Saremco Microhybrid in saliva to 51.1 for Filtek Supreme in red wine. All materials showed significant changes in color after 4 weeks of immersion in staining solutions. Significant differences were found between the tested composite resins and also between the staining solutions

Influence of mechanical and chemical degradation on surface gloss of direct and CAD-CAM resin composite materials

To compare the gloss retention of four resin based materials, two direct resin composites (Tetric EvoCeram and Filtek Supreme) and two indirect resin composite CAD-CAM blocks (Tetric CAD and Lava Ultimate)

Efficiency of 3D-printed composite resin restorations compared with subtractive materials: Evaluation of fatigue behavior, cost, and time of production

Statement of problem: Three-dimensionally (3D)-printed composite resins have been marketed as materials for definitive restorations. However, limited information is available regarding the stability of the adhesive interface and the efficiency of 3D-printed composite resins. Purpose: The purpose of this in vitro study was to evaluate the integrity of the marginal adhesive interface before and after thermal and mechanical fatigue of an initial formulation of a 3D-printed composite resin and to evaluate the efficiency of this manufacturing method. Material and methods: Freshly extracted molars were prepared for onlays and adhesively restored with either 3D-printed composite resin (VarseoSmile Crown Plus) (Group 3D), milled composite resin (Tetric CAD) (Group MCOMP), milled PMMA (Telio CAD) (Group PMMA), and milled lithium disilicate (IPS e.max CAD) (Group EM). Marginal analysis was performed under a scanning electron microscope before and after fatigue by thermomechanical cyclic loading, and initial and terminal percentages of continuous margin (%CM) were compared. The time required for the production of each type of restoration was recorded, and the production costs were also compared. Results: Before aging, 3D, MCOMP, and EM presented comparable values of %CM (69.8%, 75.9%, and 63.1%, respectively) that were statistically significantly higher (P&lt;.05) than those of PMMA (45.1%). After aging, 3D and EM had comparable results (44.7% and 43.7%, respectively), which were lower than those of the MCOMP group (68.5%) but higher than those of the PMMA group (20.5%). Regarding time efficiency, 3D printing took less time than MCOMP or PMMA if more than 8 restorations were fabricated. For the production costs, 3D printing was 5.5, 8.7, and 10.2 times less expensive than PMMA, MCOMP, and EM, respectively. The initial equipment cost was also lower for the additive manufacturing method. However, 3D printing did not always considerably reduce waste. Conclusions: In terms of marginal adaptation, the evaluated initial formulation of a 3D-printed composite resin behaved similarly to other well-established definitive restoration materials and better than milled PMMA, both before and after fatigue. Three-dimensionally printed resins present advantages in terms of equipment and consumable costs, even for a single restoration, but also for production time when more than 8 restorations were fabricated.</p