Comparison of digitally assessed quality of posterior crown preparations performed with and without previous practice on patient-specific three-dimensional-printed teeth models.

INTRODUCTION: Three-dimensional (3D)-printing technology can provide customizable simulations, but its effects on patient care quality have not been well studied. This study aimed to assess the impact of practicing with patient-specific 3D-printed teeth models on the quality of patients' dental preparations performed by students transitioning to clinical training. Accordingly, the quality of posterior crown preparations was evaluated by objectively analyzing digital scans and grades in two groups: the study group, which practiced beforehand with patient-specific 3D-printed teeth models, and the control group, which did not practice with these models. METHODS: All 78 fourth-year dental students who had just finished their fixed prosthodontics course at the simulation laboratory with training on phantom heads and without previous clinical experience in crown preparations were invited to participate in the study. Sixty-eight agreed to take part and were randomly divided into a study group that practiced crown preparations on 3D-printed models of their own patient's teeth and a control group that did not practice with 3D-printed models and started their clinical work straightforwardly after simulation training. Students completed validated perception questionnaires on self-confidence and clinical skills before and after the protocol, which were compared using a chi-squared test. Crown preparations performed on 3D-printed models and then on patients were digitally scanned and objectively graded by prepCheck software for critical parameters, such as undercuts, taper, and occlusion reduction. Non-parametric tests were used to compare preparations on 3D-printed models and on patients performed by the study group and those on patients made by the control group. RESULTS: Initially, both groups reported similar perceptions of self-confidence and clinical skills levels. The study group significantly improved both aspects after the protocol. Analysis of the scanned preparations demonstrated that the study group removed less tooth structure from actual patients than from the initial 3D-printed models. In contrast, the control group showed excess occlusal clearance in their patients compared to the study group. CONCLUSIONS: Practicing patient-specific 3D-printed teeth before performing procedures clinically appears to enhance preparation quality and minimize unnecessary tooth reduction in early clinical experiences.

Repair Bond Strength of Aged Composite Resins Using Different Surface Treatment Protocols.

This study evaluated shear bond strength (SBS) of thermally aged composite resins repaired using different surface protocols. Four-hundred composite resin samples were made using the following materials (100 samples per material): Filtek Z350XT (FXT); Spectra Smart (SSM); IPS Empress Direct (EDI); and Forma (FOR). Each group's samples were then divided into 10 groups (n = 10 samples per group): G1: no surface treatment; G2: phosphoric acid-etching + universal-adhesive (PU); G3: surface roughening + PU (RPU); G4: RPU + silane (RPSU); G5: surface roughening + hydrofluoric acid-etching + universal adhesive (RHU); G6: RHU + silane (RHSU); G7: dry sandblast + PU (DsPU); G8: DsPU + silane (DsPSU); G9: wet sandblast + PU (WsPU); and G10: WsPU + silane (WsPSU). G1 was freshly repaired, and G2 to G10 were thermally aged before repair. Specimens were tested for SBS, and the failure type was observed with a magnifying loupe. Representative images were obtained using a scanning electronic microscope. Data were analyzed by two-way analysis of variance and Tukey post hoc tests (P = .05). Differences were detected among different surface treatments and among different composite resins with equal surface treatments (P < .05). SBS means ranged from 10.48 (FOR:G2) to 20.70 (FXT:G7). The highest SBS values were seen in G7 to G10 (P > .05), while lowest values were generally observed for G2. G1 showed higher results compared to G2 (P < .05), except for EDI (P > .05). Most failures corresponded with cohesive type. In general, thermally aged composite resin presented a decreased repair bond strength potential when no additional surface treatment was applied. Sandblasting improved the SBS of repaired aged composite resins.

Effect of scanning strategies on the accuracy of digital intraoral scanners: a meta-analysis of in vitro studies.

PURPOSE: This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis. MATERIALS AND METHODS: This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05. RESULTS: The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16). CONCLUSION: The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.

Comparison of a resin-based sealant with a nano-filled flowable resin composite on sealing performance of marginal defects in resin composites restorations: a 36-months clinical evaluation.

OBJECTIVES: Our goal was to evaluate the clinical behavior of resin-based composite (RBC) restorations with sealed marginal defects using nano-filled flowable RBCs (FRS) compared with resin-based sealant (RBS); this work used marginal adaptation, marginal staining, and secondary caries according to the World Dental Federation (FDI) criteria. MATERIALS AND METHODS: This was a prospective, randomized, double-blind, controlled trial. Fifty-four patients who met the inclusion criteria (older than 18 years old; with high cariogenic risk determined by Cariogram software; and restorations with marginal defects, 3 and 4 according to FDI criteria) were randomly divided into three groups. There were three defective RBC restorations per patient and were repaired (n = 162). The groups were RBS-marginal sealing using a resin-based sealant (Clinpro Sealant, 3 M ESPE, MN, USA) plus adhesive (Single Bond Universal, 3 M ESPE, MN, USA); FRS-sealing using flowable resin (Filtek Flow Z350XT, 3 M ESPE, MN, USA) plus adhesive (Single Bond Universal, 3 M ESPE, MN, USA); and control-no repair treatment. All procedures were performed under complete isolation. Evaluations were evaluated at 1-week post treatment (baseline) as well as at 18 and 36 months after treatment regarding marginal adaptation, marginal staining, and secondary caries according to FDI criteria. The data were analyzed using the Wilcoxon test (α = 0.05) to compare the differences in each treatment group at different evaluation times. RESULTS: Marginal adaptation of micro-repaired RBC restorations were seen in patients with a high risk of caries using flowable resin composite or resin-based sealants. There were differences (P < 0.001) when baseline was compared at 18 and 36 months. Marginal staining showed differences when baseline was compared to 18 months (P < 0.001) and 36 months (P = 0.001) for both treatments. Secondary caries parameters for RBS treatment showed differences when baseline was compared to 36 months (P = 0.025) and when 18 months was compared to 36 months (P = 0.046). CONCLUSIONS: Micro-repair of RBC restorations resulted in clinical deterioration of marginal adaptation and marginal staining. Nano-filled flowable resin composites were sealed on defective restorations; 3 and 4 FDI marginal defects have better clinical performance to prevent secondary caries than resin-based sealants after 36 months. CLINICAL RELEVANCE: Micro-repair with RBS does not seem to be an effective treatment to prevent secondary caries.

Students' and tutors' perceptions of a deliberate simulated practice using patient-specific virtual and three-dimensional printed teeth models: A pilot study.

OBJECTIVE: This pilot study aimed to investigate the perceptions of dental students and their tutors of a deliberate simulated practice using patient-specific virtual and three-dimensional (3D) printed teeth models. This is before they perform their first indirect posterior tooth restoration on their patients. METHODS: Seventy-eight fourth-year dental students from the 2021 Comprehensive Clinic I course at the University of the Andes, Chile, were invited to participate in a deliberate practice protocol. This consisted of digitally scanning their patients' teeth, printing the files three-dimensionally, and loading them into a virtual reality (VR) dental simulator to create patient-specific models. Subsequently, they practiced the same indirect posterior restorations on these models before performing them on their actual patients. Perceptions about students' preparedness to perform tooth preparations before and after the protocol were collected from students and their tutors through surveys. RESULTS: Sixty-three students (43 female) and six clinical tutors (all male) participated in the study. Before practicing with their patient-specific models, most students believed they had the knowledge, practical skills, and self-confidence to perform indirect restorations on their patients. However, after the protocol, most students thought their self-confidence increased and felt better prepared to treat their patients. Most students preferred the 3D-printed models over the VR models to practice but mentioned that it did not feel like drilling dental enamel. Tutors believed that participating students had higher self-confidence when treating their patients and were more autonomous. CONCLUSIONS: This study demonstrated that students and clinical tutors had positive perceptions of practicing with patient-specific virtual and 3D-printed teeth models before students performed their first indirect restorations on their patients.

Novel Trends in Dental Color Match Using Different Shade Selection Methods: A Systematic Review and Meta-Analysis.

Since color matching is considered a subjective procedure, accurate shade choice is often the most challenging stage of recreating the natural appearance of teeth. Furthermore, accurate determination of tooth color is imperative for the final outcome of dental restorations. The purpose of this research is to assess the accuracy of color match between diverse shade selection methods throughout a systematic review and meta-analysis. Two independent investigators (L.H. and R.B.) screened the literature in five electronic databases. Randomized controlled trials or in vitro papers studying the effect of using either digital shade selection or visual shade selection on the accuracy of color match were included. A total of 13 manuscripts comprised the meta-analysis. Color difference (ΔE) between restorations where the shade matching was performed by the conventional method was greater than those where the shade matching was performed by computerized methods (p = 0.007). According to the subgroup analysis, only the use of digital photographs for shade matching showed a reduction in the (ΔE) (p < 0.0001), while the use of a spectrophotometer has no advantages over the use of visual shade guide tabs (p = 0.57). On the other hand, global analysis showed that incorrect shade matching was higher when the conventional method using shade guide tabs was used (p < 0.001), irrespective of whether a spectrophotometer or a digital camera was used (p < 0.001). This study concluded that the use of digital photography and spectrophotometric measurements led to fewer color differences and less incorrect shade matching than conventional methods using color shade tabs.

A comparison of ceramic crown color difference between different shade selection methods: Visual, digital camera, and smartphone.

STATEMENT OF PROBLEM: The light source stability of digital cameras and smartphones is important in shade matching in restorative and prosthetic dentistry to communicate objectively with the dental laboratory. Techniques that standardize the light source of such devices are lacking, and this limitation can lead to color mismatches, difficulties in color communication, and treatment documentation. PURPOSE: The purpose of this clinical study was to compare the magnitude of color difference (ΔE) among 3 shade selection methods during the fabrication of ceramic crowns: visual shade selection with a shade guide, digital shade selection with a digital camera and cross-polarizing filter, and digital shade selection with a smartphone and a light-correcting device. MATERIAL AND METHODS: Forty-five patients in need of ceramic crowns were enrolled, and shade selection was evaluated according to different protocols: visual shade selection (A-D shade guide and IPS Natural Die Material Shade Guide, sent to the dental laboratory technician via a laboratory prescription); digital shade selection with a digital camera (D7000; Nikon Corp) with an 85-mm lens and wireless close-up flash, with and without a cross-polarizing filter (Polar eyes); and digital shade selection with a smartphone and a light-correcting device (iPhone XS attached to Smile Lite MDP, with and without its cross-polarizing filter accessory). Information from the smartphone was imported to an app (IPS e.max Shade Navigation App; Ivoclar AG) that converted the reading to a shade and level of translucency for the ceramic restoration. For all photographs, a gray reference card with known color values was positioned by the mandibular teeth and was used for white balancing of the digital photographs with a software program. All photographs were edited and sent to the dental laboratory: white-balanced with the shade guide; white-balanced with the substrate shade guide; black and white; saturated; and cross-polarized. Ceramic crowns were made with the same lithium disilicate material (IPS e.max CAD; Ivoclar AG) and cemented with the same resin cement (RelyX Ultimate Clicker, A3 shade; 3M). The ΔE values between the crown and the adjacent tooth were determined. The data were analyzed by using a 1-way analysis of variance (ANOVA) and Tukey post hoc tests (α=.05). RESULTS: The mean ΔE between a cemented ceramic crown and the adjacent tooth in the visual shade selection group was 5.32, significantly different than both digital camera (ΔE=2.75; P=.002) and smartphone (ΔE=2.34; P=.001), which were not different from each other (P=.857). CONCLUSIONS: The digital shade selection with photographs acquired with both a digital camera and a smartphone with a light-correcting device showed a threshold within the acceptable values (ΔE<3.7), whereas the visual shade selection showed an average ΔE above the threshold for acceptable values (ΔE>3.7). The use of a gray reference card helped standardize the white balance from the digital images.

Accuracy of Dental Photography: Professional vs. Smartphone's Camera.

There is a scant literature on the accuracy of dental photographs captured by Digital Single-Lens Reflex (DSLR) and smartphone cameras. The aim was to compare linear measurements of plaster models photographed with DSLR and smartphone's camera with digital models. Thirty maxillary casts were prepared. Vertical and horizontal reference lines were marked on each tooth, with exception to molars. Then, models were scanned with the TRIOS 3 Basic intraoral dental scanner (control). Six photographs were captured for each model: one using DSLR camera (Canon EOS 700D) and five with smartphone (iPhone X) (distance range 16-32 cm). Teeth heights and widths were measured on scans and photographs. The following conclusions could be drawn: (1) the measurements of teeth by means of DSLR and smartphone cameras (at distances of at least 24 cm) and scan did not differ. (2) The measurements of anterior teeth by means of DSLR and smartphone cameras (at all distances tested) and scan exhibited no difference. For documentational purposes, the distortion is negligeable, and both camera devices can be applied. Dentists can rely on DSLR and smartphone cameras (at distances of at least 24 cm) for smile designs providing comparable and reliable linear measurements.

Evaluation of the effectiveness in teeth whitening of a single session with 6% hydrogen peroxide Laser/LED system.

BACKGROUND: Due to the current importance of dental whitening, multiple studies have been carried out in order to achieve an efficient, effective, and innocuous procedure. This study aimed to compare the effectiveness and sensitivity of in-office dental bleaching with one versus two applications of 6% hydrogen peroxide (HP) gel with nitrogen titanium dioxide (TiO2) nanoparticles activated by LED/Laser lamp in a single-session. METHODS: This RCT with a split-mouth design was performed in twenty-seven volunteers. The in-office dental bleaching technique was performed using 6% HP with nitrogen TiO2 nanoparticles. In each patient, groups were randomized by hemiarch: Group 1 received one application of 72 minutes and Group 2 received two applications of 36 minutes, both groups in a single-session. RESULTS: There were no significant differences in the effectiveness of a single-session with one or two applications of 6% HP with nitrogen TiO2 nanoparticles between both groups(p>0.05). A positive and increase of ∆E value was observed in both groups. Group 1 showed an increase of 4.45 in the immediate measurement, remaining at 4.41 until the one-week control, to increase up to an ∆E of 4.99 at one-month control. Group 2 showed a sustained increase of 4.02 units in the immediate control until reaching the maximum value of 5.46 units of ∆E at one-month control. CONCLUSION: One session single application protocol of 6% Hydrogen Peroxide gel with nanoparticulate TiO2 activated by LED/Laser is effective and efficient for dental bleaching.

Evaluation of trueness and precision of two intraoral scanners and a conventional impression: an in vivo clinical study.

OBJECTIVE: To evaluate, in vivo, trueness and precision of two intraoral scanners, CEREC Omnicam (OMNI) and CEREC Primescan (PRIM), compared to a conventional impression serving as a master model. METHOD AND MATERIALS: Impressions were performed for seven participants. For each participant, conventional polyvinylsiloxane impression and digital impressions using two intraoral scanners, OMNI (software 4.6; CEREC ORTHO Protocol) and PRIM (10 digital impressions per participant, per scanner), were made. Conventional impression was digitized with a laboratory scanner (INEOS X5), and used as reference model. .STL files were superimposed with software (Geomagic Control X) using the tools Initial Alignment and Best Fit Alignment, and trueness and precision were evaluated. Statistical evaluation was performed with Shapiro-Wilk and Mann-Whitney tests (P < .05). RESULTS: Total mean trueness for the OMNI system was 56.45 ± 7.80 µm, and 47.29 ± 5.47 µm for the PRIM system. Regarding precision, values from the OMNI system were 42.47 ± 6.91 µm and from the PRIM system 21.86 ± 4.40 µm. PRIM presented better results for both trueness (P = .000) and precision (P = .000) when compared to OMNI. CONCLUSIONS: PRIM provided a better combination of trueness and precision than its predecessor OMNI. However, both PRIM and OMNI performed acceptably when performing indirect restorations, according to the current acceptable thresholds, considering both trueness and precision. CLINICAL IMPLICATIONS: Full-arch impressions with Primescan presented more precision and trueness than Omnicam; however, compared to previous reported values of conventional impressions, they still presented lower accuracy.

Effect of different fabrication steps on color and translucency of a CAD-CAM feldspathic ceramic.

OBJECTIVE: To evaluate color differences (ΔE) of different fabrication steps performed on a feldspathic ceramic and relative translucency parameter (RTP) after glazing; and to evaluate their effects on the color parameters: L*, a* and b*. MATERIAL AND METHODS: Computer-aided design/computer-aided manufacturing (CAD-CAM) feldspathic maxillary right central incisor ceramic crowns (Cerec Blocs; 1.4 mm thickness) were fabricated through scanning a model preparation and milling. A total of 20 specimens were used and different parameters were compared with each other for color difference (ΔE): original block, milling, polishing, glazing and try-in cements; RTP was measured after glazing. Color parameters (L*, a*, and b*) were evaluated after each step with a spectrophotometer (Vita Easyshade V) and compared using the CIEDE2000 formula. Statistical analyses were done using one-way ANOVA and post-hoc tests. RESULTS: The highest ΔE value was observed for Original versus Milling group (4.73) and the lowest for Polishing versus Glazing (0.49). RTP after glazing presented a value of 12.01. L*, a*, and b* parameters were different among groups. Milling group was the one that presented more differences compared to the Original block regarding L*, a*, and b* parameters. CONCLUSIONS: Different fabrication steps resulted in perceptible color differences within themselves, and L*, a*, and b* parameters changed according to each step. All milling specimens presented unacceptable color differences when compared to the other steps, and milling specimens showed all color parameters (L*, a*, and b*) statistically different compared to the Original block. A high RTP value was observed, demonstrating that, at 1.4 mm thickness, the feldspathic ceramic presented high translucency, showing that opacification of substrate might be necessary. CLINICAL SIGNIFICANCE: Different fabrication steps can greatly affect the optical properties of the feldspathic ceramic restoration studied and cause a relevant impact when compared to the ceramic block itself. Crowns evaluated right after milling presented the highest color differences. In order to obtain optical properties as close as possible to the original feldspathic ceramic block, either polishing or polishing and glazing needs to be performed.

Tasa de supervivencia de prótesis fija unitaria de cerámica feldespática y feldespática reforzada / Survival rate of feldspathic and reinforced feldspathic ceramic single-unit fixed prostheses

Introducción: Gracias a su eficiencia y al uso exclusivo de cerámicas libres de metal, en rehabilitación oral se ha logrado alcanzar los estándares estéticos y mecánicos, manteniendo o, incluso, superando, la calidad de los tratamientos en comparación con las restauraciones metal cerámicas tradicionales. Actualmente los mecanismos de confeccion de cerámica libre están evolucionando cada vez mas hacia las tecnologías maquinadas CAD-CAM y disminuyendo su producción mediante la técnica de Inyeccion PRESS. Objetivo: Comparar la tasa de supervivencia de prótesis fija unitaria realizadas con cerámicas feldespáticas convencionales y reforzadas con disilicato de litio, confeccionadas con sistema CAD/CAM de CEREC® chair-side, en comparación con el método de inyección de laboratorio PRESS convencional de prensión. Métodos: Revisión sistemática realizada a través de búsqueda de evidencia científica en PubMed, PubMed Clinical Queries, Epistemónikos, Tripdatabase, Cochrane Library, recursos electrónicos de la Universidad de los Andes y bibliografía retrógrada, de artículos publicados hasta el año 2019. Se incluyeron todos aquellos estudios referentes a prótesis fija unitaria de cerámicas feldespática convencional y feldespática reforzada con disilicato de litio, confeccionadas mediante CAD/CAM y/o método convencional. Resultados: Un total de 28 artículos cumplieron los criterios de inclusión: 21 estudios observacionales de cohorte, 4 ensayos clínicos aleatorizados y 3 no aleatorizados. A corto y mediano plazo, CAD/CAM de CEREC® registró tasas de supervivencia de 98 por ciento y 91,9 por ciento, respectivamente. El sistema convencional registró tasas de supervivencia de 97,5 por ciento a corto plazo y 93 por ciento a mediano. Conclusiones: A corto plazo se describe en la literatura que CAD/CAM de CEREC® tuvo una tasa de supervivencia ligeramente superior al sistema convencional. Por otro lado, a mediano plazo CAD/CAM de CEREC® presentó una leve disminución respecto al sistema convencional. Aún no hay estudios disponibles para determinar la supervivencia clínica de los tratamientos a largo plazo(AU)

Introduction: Thanks to its efficiency and the exclusive use of metal-free ceramics, in oral rehabilitation it has been possible to achieve aesthetic and mechanical standards, maintaining or even exceeding the quality of the treatments compared to traditional metal-ceramic restorations. Currently, free ceramic manufacturing mechanisms are increasingly evolving towards CAD-CAM machined technologies and decreasing their conventional production through the PRESS Injection technique. Objective: Compare the survival rate of single-unit fixed prostheses made with conventional feldspathic ceramics and reinforced with lithium disilicate by the CEREC® CAD/CAM chairside system, with the conventional PRESS laboratory injection method. Methods: A systematic review was conducted of scientific evidence included in papers published until the year 2019 in PubMed, PubMed Clinical Queries, Epistemonikos, Tripdatabase, Cochrane Library, electronic resources of Los Andes Peruvian University, and retrograde bibliography. The papers selected dealt with conventional and lithium-disilicate reinforced feldspathic ceramic single-unit prostheses made by CAD/CAM and/or the conventional method. Results: A total 28 papers met the inclusion criteria. Of these, 21 were observational cohort studies, four were randomized clinical assays and three were non-randomized assays. Short- and mid-term, CEREC® CAD/CAM achieved survival rates of 98 percent and 91.9 percent, respectively. The conventional system achieved survival rates of 97.5 percent short-term and 93 percent mid-term. Conclusions: As described in the literature, CEREC® CAD/CAM had a slightly higher survival rate than the conventional system in the short term. In the medium term, however, CEREC® CAD/CAM displayed a slight reduction in comparison with the conventional system. No studies are available to determine the clinical survival of the treatments in the long term(AU)

Improvement preclinical and clinical skills for dental preparations using assisted training software.

INTRODUCTION: Digital workflow is currently available for different fields of dentistry. Additionally, to clinical use, digital technology is focused on the education and training of students. The objective of this study was to show the potential benefit of the use of digital CAD / CAM technology and assisted training software in the evaluation and improvement of student skills in preclinical and clinical environments. MATERIALS AND METHODS: 30 models of dental preparations were digitalised and analysed by PrepCheck software, after that was used the PrepCheck Report tool, gathering the results of the analysis in an automatically created report and containing the following parameters: analysis of the conicity, distance between a preparation and the opposing jaw, analysis of the type of preparation, quality of the margin and total occlusal convergence. RESULTS: The use of the PrepCheck Pro 2.1 software makes evident the errors made by the students during the biomechanical preparation, since they generally change the inclination, in order to have less difficulties to comply with the parameters established in the preparations. Regarding the evaluated parameters for anterior and posterior fixed prosthesis) such as: 'Conicity', 'Type of preparation' and 'Distance to the antagonist', the preparations, in their majority, were classified within the tolerance range with of 50-60%, 80-93% and 53-67%, respectively. CONCLUSION: This pilot study demonstrated the benefits of using software and CAD/CAM technology in both preclinical and clinical environments for teaching and learning. Its use on preclinical environments allows the student observe qualitatively and quantitatively a preparation flaws when compared to a master's preparation. Lastly, the ease of visualising errors associated with magnification would allow students to improve their skills.

Comparison of visual analog shade matching, a digital visual method with a cross-polarized light filter, and a spectrophotometer for dental color matching.

STATEMENT OF PROBLEM: During the selection of tooth color, subjective communication with the laboratory and an incorrect color registration technique can lead to a poor color match of a restoration to adjacent teeth and oral structures. PURPOSE: The purpose of this cross-sectional study was to compare color registration and color matching in a young Chilean population with 3 different methods: visual with a shade guide, digital visual with a cross-polarized filter, and instrumental with a spectrophotometer. MATERIAL AND METHODS: A total of 60 young volunteers were selected for tooth color registration of the maxillary right central incisor by using 3 different methods. Tooth color registration was performed using the CIELab and ΔE coordinate system. RESULTS: Significant differences were detected between the coordinates recorded by the visual analog method in comparison with the other 2 methods. In contrast, no significant differences were found between the L∗ and b∗ coordinates of the spectrophotometer and the digital visual method with use of a cross-polarization filter. The ΔE obtained between the visual shade and spectrophotometer was 7.35, and the ΔE between the digital visual method with the use of a cross-polarization filter and the spectrophotometer was 6.12. CONCLUSIONS: No statistically significant differences were observed in the digital image with the cross-polarization filter and the spectrophotometer in the L∗ and b∗ coordinate of the CIELab system. In contrast, the visual analog method led to large differences with the other methods under study. The ΔE of the digital visual method with the use of cross-polarization filters and the spectrophotometer was 6.2, considered as an acceptable color mismatch (<ΔE 6.8).

Prevalencia e intensidad de sensibilidad posoperatoria durante el tratamiento de prótesis fija / Prevalence and intensity of postoperative hypersensitivity during fixed prosthodontic treatment

RESUMEN Introducción: Durante la realización de prótesis fijas, el paciente puede presentar sensibilidad posoperatoria. Se ha descrito en la literatura diferentes prevalencias de esta sensibilidad, las cuales varían ampliamente, entre 3 por ciento y 34 por ciento. Objetivo: Determinar la prevalencia e intensidad de sensibilidad posoperatoria en el tratamiento de prótesis fija sobre diente vital. Métodos: se realizó un estudio clínico piloto descriptivo. La muestra fue de 35 dientes tratados de 20 pacientes. Esta fue conformada por pacientes atendidos por alumnos del Centro Odontológico de la Universidad de Los Andes, a los cuales se les realizó un tratamiento en base a prótesis fija sobre diente vital, desde el mes de abril hasta octubre del año 2015. Se registró la sensibilidad durante el tratamiento por medio la escala visual análoga a través de un diario completado por el paciente y por la escala verbal numérica aplicada por el investigador en distintas etapas clínicas. Resultados: Se observó una prevalencia del 31,4 por ciento con una intensidad de 0,62 ± 0,49 según la escala visual análoga y de 0 según la escala verbal numérica. Conclusiones: la prevalencia de la sensibilidad posoperatoria se aproximó al rango más alto descrito en la literatura. La intensidad de la sensibilidad observada fue leve a imperceptible clínicamente(AU)

ABSTRACT Introduction: During fixed prosthodontic treatment, patients may present postoperative hypersensitivity. The prevalence rates contained in the literature on the topic range from a mere 3 percent to 34 percent. Objective: Determine the prevalence and intensity of postoperative hypersensitivity during fixed prosthodontic treatment of vital teeth. Methods: A pilot descriptive clinical study was conducted. The sample was 35 treated teeth from 20 patients. These patients had been treated by students from the Dental Center at the University of Los Andes, and had undergone fixed prosthodontic treatment on vital teeth from April to October 2015. Hypersensitivity during the treatment was recorded with the visual analog scale based on a diary kept by patients and on the verbal numerical rating scale as applied by the researcher at the various clinical stages. Results: Prevalence was 31.4 percent with an intensity of 0.62 ± 0.49 by the visual analog scale and of 0 by the verbal numerical rating scale. Conclusions: The prevalence of postoperative hypersensitivity approached the highest range described in the literature, whereas the intensity of hypersensitivity ranged from mild to clinically imperceptible(AU)

Comparison of a non-destructive technique using three-dimensional imaging and histoanatomical chemical dissolution for dental morphology analysis.

AIM: The present work aims to compare a digital dental histoanatomical analysis method with chemical enamel dissolution for the study of dental morphology. MATERIAL AND METHODS: Extracted maxillary anterior teeth were scanned under microcomputed tomography (µCT) (µCT 40; Scanco Medical), segmented, and reconstructed three-dimensionally (Amira, version 5.5.2; VSG). Following the digital acquisition of dental morphology, all specimens were acid treated with 5% formic acid for careful dissolution of the enamel layer. Six measurements (three buccopalatal and three mesiodistal) per specimen were performed, both digitally following the µCT scan and physically both before and after enamel dissolution. The obtained measurements were subjected to statistical analysis through concordance coefficient measurements and linear regression. RESULTS: A straight line correlation behavior with no statistically significant difference was found between both methods, with a concordance correlation coefficient of 97%. CONCLUSION: The digital, nondestructive, µCT-layered, three-dimensional reconstruction method presented comparable results to acid-etched enamel dissolution, confirming that both options are reliable for the histoanatomical analysis of enamel and dentin morphologies.

Factores de riesgo asociados a sensibilidad dental en el tratamiento con protésis dental fija. Revision de literature / Risk factors associated with tooth sensitivity in fixed dental prosthesis treatment: a literature review

Las piezas dentarias vitales que reciben tratamiento en base a prótesis dental fija (PDF) sufren un proceso inflamatorio pulpar durante su preparación, esta respuesta inflamatoria puede ser transitoria o perpetuarse y convertirse en un daño pulpar. Como consecuencia se puede presentar sensibilidad post operatoria en algunos pacientes durante el tratamiento y esta podría estar relacionada con ciertos factores de riesgo. El objetivo del presente trabajo es describir los factores de riesgo relacionados con la sensibilidad postoperatoria termica, quimica o mecanica en el tratamiento mediante prótesis dental fija. Método: Se utilizaron diferentes bases de datos para buscar estudios que incluyeran las siguientes palabras clave: sensibilidad dental, hipersensibilidad dental, respuesta pulpar, corona, prótesis fija, postoperatorio, post cementación, preparación dentaria. Todos los estudios encontrados se analizaron según el nivel de evidencia, la calidad del informe y las implicaciones éticas. Resultados: Se seleccionaron un total de 43 artículos. De ellos, 10 correspondieron a estudios clínicos, 7 revisiones de literatura y 26 estudios in vitro. El nivel de evidencia, la calidad del informe y las consideraciones éticas fueron calificados como regulares. Conclusiones: La evidencia existente describe algunos factores de riesgo relacionados con la sensibilidad postoperatoria en tres etapas del proceso de confección de una prótesis dental fija, pero sin embargo no es concluyente respecto a su mecanismo de origen ni prevención por lo que se sugiere realizar estudios clínicos aleatorizados.

Variability of color matching with different digital photography techniques and a gray reference card.

STATEMENT OF PROBLEM: Color matching in restorative and prosthetic dentistry is important for the success of dental treatments, although communication with the dental laboratory remains subjective, and studies of the performance of objective communication methods are lacking. PURPOSE: The purpose of this study was to evaluate color differences (ΔE) and compare color luminosity (L*) values among different types of digital photography equipment used to document tooth color, with and without a gray reference card, and to determine whether the gray card could be used to standardize color assessment in dental photography. MATERIAL AND METHODS: Sixty photographs were made (n=10) using different equipment: a D7000 digital camera (Nikon Corp) with an 85-mm lens and wireless close-up flash (DC+WCF); close-up flash surrounded by 80 grams per square meter (gsm; specification of paper thickness) white printing paper (DC+WPP); ring flash (DC+RF); close-up flash attached to a dual-point rigid flash bracket (DC+DPRF); cross-polarizing filter attached to a close-up flash (DC+CPF); and iPhone 7 (I7). For all photographs, a gray reference card with known color values was positioned at the patients' mandibular teeth, acting as a parameter for the analysis of white-balanced digital photographs. Each photograph underwent white balance with the reference card and software. ΔE were obtained from each piece of equipment by comparing images with and without white balance (original photo) with software and the smallest ΔE achieved was used as the gold standard for comparisons of luminosity. Values of luminosity were subsequently obtained for the different equipment with and without white balancing the photographs; these values were compared using a general estimating equation with Huber-White standard error (α=.05). RESULTS: The use of a cross-polarizing filter was used as the gold standard for luminosity evaluation, as the smallest ΔE (3.4) among photographs were observed when those with and without white balance were compared. Luminosity results from the cross-polarizing filter method (DC+CPF) were not significantly different from those of the DC+DPRF (P=.73), DC+WPP (P=.106), and DC+WCF (P=.551) groups but were statistically different from DC+RF (P=.028) and I7 groups (P<.001). Use of a gray card was significant when a ring flash (P=.008) or the iPhone (P=.023) were used but not statistically significant for the other groups (P>.05). CONCLUSIONS: The use of a cross-polarizing filter results in more color-standardized photographs, while the ring flash system and the iPhone 7 result in less standardized photographs. The gray reference card had a significant effect when a ring flash system or iPhone 7 was used.

Prevalence of tooth forms and their gender correlation.

OBJECTIVE: This study evaluated different tooth shapes from female and male genders, matching them with the firstly proposed pure basic forms, and proposed different hybrid shapes; it also evaluated the percentage of correct gender identification of lay people, dentists and dental students. MATERIALS AND METHODS: Standardized digital photos were taken from 460 people and analyzed by 3 experts regarding genders and tooth forms: pure basic forms-oval (O), triangular (T), square (S) and rectangular (R); and combined hybrid forms-oval-rectangular (OR), triangular-rectangular (TR), triangular-oval (TO), square-oval with flat lateral incisors (SOF), and square-oval with scalloped lateral incisors (SOS). Then, correct gender identification (%) was evaluated among lay people, dentists and dental students (n = 10). RESULTS: Pure forms showed less prevalence in the population studied (O:6.52%; S:3.48%; T:3.26%; R:2.39%) than hybrid ones (TO:20.87%; SOS:20.65%; OR:19.57%; SOF:16.96%;TR: 6.30%). Tooth gender selection among different evaluators was not significantly different (≈50% correct answers). CONCLUSIONS: No correspondence exists between tooth shapes and patient genders. Pre-standardized pure tooth forms appeared less than hybrid ones, while the most frequently found in the population studied were TO, SOS, and OR forms, disregarding genders. CLINICAL SIGNIFICANCE: Esthetic perception is an increasingly important criterion critical to satisfy patients. The correlation of reported tooth shapes with specific genders was not reliably observed in natural smiles. Tooth shapes should be selected according to the wishes of the patient rather than by previously believed gender specific tooth shapes. Pure basic tooth forms should be complemented with the addition of combination forms to more accurately portray forms found in nature.

Preliminary Evidence for the Complete Digital Esthetic Rehabilitation Treatment: Case Report and 1-Year Follow-up.

PURPOSE: To show through computer-aided design and manufacturing technology combined with novel digital acquisition images and the right restorative material that the technology can provide an easier and predictable workflow for general practitioners. BASIC PROCEDURE: This case report presents a fully digital treatment of a 59-year-old patient with tooth-supported crowns and provides a detailed step-by-step digital technique to obtain a successful result. CONCLUSION: By avoiding traditional impression and fixed prosthetic techniques, excellent clinical results can be obtained, minimizing the required steps and simplifying the overall procedure. This adds information to the current literature, allowing general practitioners to choose the best treatment option. The function and esthetics remained unaltered over a 1-year follow-up period. No fracture or decementation was observed.