Faculty Bibliography

OBJECTIVE:To describe a shift from injectable resin composite technique to composite resin computer-aided design and computer-aided manufacturing (CAD/CAM) veneers in addressing esthetic concerns associated with diastemas between anterior lower teeth in a clinical case. CLINICAL CONSIDERATIONS/METHODS:Among several techniques proposed for direct resin composite restoration, the "Injectable resin composite technique" has gained popularity for its time-efficiency, reduced technique sensitivity, and diminished reliance on clinician skills. However, challenges such as staining and the need for frequent polishing follow-ups may prompt the consideration of more stable alternatives such as indirect veneer restorations. While ceramic veneers offer superior mechanical and optical properties, resin ceramic veneers, especially those milled from CAD/CAM resin ceramic blocks, offer advantages such as rapid, cost-effective production, simplified intra-oral repairs, less susceptibility to fracture, superior stress absorption, and requires minimal tooth preparation, making them an appealing option for many patients. Moreover, a fully-digital approach not only streamlines the process but also saves time and labor while ensuring the delivery of high-quality restorations to patients. CONCLUSION/CONCLUSIONS:In addressing a patient's dissatisfaction with constant polishing of direct resin composite restorations, a shift to resin composite CAD/CAM veneers was implemented. Utilizing a fully-digital approach with CAD/CAM resin ceramic restorations successfully restored both esthetics and function. CLINICAL SIGNIFICANCE/CONCLUSIONS:While the injectable resin composite technique achieves immediate esthetic results, its low color stability necessitates frequent polishing sessions. The replacement of direct resin composite restorations with CAD/CAM resin composite veneers becomes a viable option for patients seeking more stable restorations that require fewer follow-ups. This transition addresses both esthetic concerns and the need for enduring solutions in restorative dentistry.

PURPOSE/OBJECTIVE:To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra-translucent zirconia crowns for posterior teeth restorations. MATERIALS AND METHODS/METHODS:Fifty-four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y-TZP (Zirconn Translucent, Vipi), and (3) 5Y-PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth-motion step-stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope. RESULTS:Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95-99) regarding 3Y-TZP and 5Y-PSZ groups (84% CB: 65%-93% and 79% CB: 37&-94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%-91%) was higher than 5Y-PSZ (20% CB: 4%-44%) and not significantly different from 3Y-TZP (54% CB: 32%-72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface. CONCLUSIONS:Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high-load bearing regions must be carefully evaluated. CLINICAL SIGNIFICANCE/CONCLUSIONS:Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre-molars. Their clinical indication in high-load requirement regions must be carefully evaluated.

The natural outcome of dental composite restorations highly depends on the translucency of the enamel layer and fluorescence. This study aimed to evaluate the Translucency Parameter (TP) and Fluorescence Intensity (FI) of five different resin composite systems. Seven discs of each composite brand were prepared in a circular increasing thickness. For TP, a spectrophotometer measured the samples' colors. The color difference within the white/black backgrounds obtained the translucency parameter. For FI, samples were exposed to UV light, and ten photographs per group were taken. Each specimen was analyzed digitally. A mixed model analysis to a 95% confidence level analyzed groups differences. Higher values of TP were observed for ED and EL, followed by FZ. The lowest values were observed for EO and FO. FI values descending order was EL>FO>EO>ED>FZ. The composition of fillers and organic matrix influenced the behavior of fluorescence and translucency of resin composites. Key words:Resin composite, fluorescence, color, translucency parameter.

OBJECTIVES/OBJECTIVE:This article presents case reports highlighting over-treatments with resin composites, often misconceived as minimally invasive procedures. CLINICAL CONSIDERATIONS/METHODS:Tooth-colored restorative materials, such as ceramics and composites, have found widespread application to correct problems related to tooth color, shape, and alignment. When composite resin is used, these procedures can be done in a very conservative, cost-effective, and timely fashion. However, it is noteworthy that contemporary dental esthetic expectations are based on standards propagated by social media and other marketing and communications platforms. The abuse of and addiction to social media impacts can lead to unrealistic esthetic expectations and standards for both patients and dentists. CONCLUSIONS:After a critical discussion on ceramic veneers published in part I of this 2-part series, this article directs attention towards what has become a trendy fashion, i.e., the use of direct composite resins as "non-prep" veneers in clinical situations that arguably required no restorative intervention at all. We further explore how social media influences the decision-making processes of both professionals and patients.

INTRODUCTION/BACKGROUND:Currently, there is little clinical evidence to support the medium- and long-term survival and clinical performance of ultraconservative approaches using adhesive restorations in full-mouth restorations. The aim of this case series study was to evaluate the medium-term clinical performance of anterior and posterior adhesive restorations applied with direct and indirect techniques using resin composites and glass-ceramic-based materials. MATERIALS AND METHODS/METHODS:The inclusion criteria were an esthetic problem as the main reason for consultation and severe generalized wear of grade 2 to 4 according to the Tooth Wear Evaluation System (TWES 2.0). In addition, at each follow-up appointment, patients were required to submit a clinical-parameter-monitoring record according to the modified United States Public Health Service (USPHS) criteria. RESULTS:< 0.005) on the survival of the restorations. CONCLUSION/CONCLUSIONS:According to the results of this study, there is a significantly higher risk of restorative complications in posterior teeth compared to anterior teeth. Also, it can be concluded that the indication of adhesive anterior and posterior restorations is justified in the total oral rehabilitation of patients with severe multifactorial tooth wear, as they are associated with a low risk of failure.

OBJECTIVE:) ceramic structures fabricated using additive manufacturing (3D printing). METHODS:powder was combined with ammonium polyacrylate, hydroxypropyl methylcellulose, and polyelectrolyte to create a colloidal gel, which was then used for printing. A digital CAD model of a disc was designed, and the G-code transferred to a custom built DIW 3D printer. The control group samples were prepared using pre-crystallized ceramic blocks, which were cut to obtain discs with same dimensions as the AR group. Disc-shaped specimens from both groups were crystallized at 840 °C. Mechanical properties were evaluated using biaxial flexural strength test (BFS) and Vickers hardness test. Representative fractographic images of the specimens were acquired using scanning electron microscopy (SEM) to analyze the fracture origin and crack propagation. Energy-dispersive X-ray spectroscopy (EDS) and attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) were used for chemical analysis, and X-ray diffractometry (XRD) was performed to analyze the crystalline phases. RESULTS:) in the AM group. SEM micrographs showed a more porous microstructure associated with the 3D printed samples. SIGNIFICANCE/CONCLUSIONS:crystals and higher degrees of porosity.

PURPOSE/OBJECTIVE:To evaluate the effect of short curing time using a high-radiant emittance light on polymerization shrinkage vectors in different consistency bulk-fill composites (BFRCs) using micro-computed tomography. METHODS AND MATERIALS/METHODS:Radiopaque zirconia fillers were homogeneously incorporated and functioned as radiopaque tracers into two regular-paste: TBFill (Tetric EvoCeram Bulk Fill) and TPFill (Tetric PowerFill), and two flowable (n=6): TBFlow (Tetric EvoFlow Bulk Fill) and TPFlow (Tetric PowerFlow) resin composites. Class I cavities (4 mm depth × 4 mm length × 4 mm width) were 3D-printed and filled in a single increment: TBFill and TBFlow were light-activated using a Bluephase Style 20i (10 seconds in high-mode); TPFill and TPFlow were light-activated using a Bluephase PowerCure (three seconds). The same adhesive system (Adhese Universal) was used for all groups. Microcomputed tomography scans were obtained before and after light-activation. Filler particle movement was identified by polymerization shrinkage vectors at five depths (from 0-4 mm): top, top-middle, middle, middle-bottom and bottom. RESULTS:TPFlow showed the lowest total vector displacement, followed by TBFlow, TBFill and TPFill, significantly different among each other (p<0.05). Generally, BFRCs showed decreased vector displacement with increased depth, and higher displacement at the top-surface (p<0.05). Qualitative analysis showed a similar pattern of vector magnitude and displacement for groups TBFill and TPFill, with displacement vectors on occlusal (top) surfaces toward the center of the restoration from the top to middle areas, and relatively limited displacement at the bottom. TBFlow and TPFlow showed more displacement on the occlusal (top). CONCLUSIONS:Short curing time with high-radiant emittance on fast-curing BFRCs was shown to be a feasible option in terms of vector displacement. Flowable BFRCs presented lower vector displacement than their regular-viscosity versions.

STATEMENT OF PROBLEM/BACKGROUND: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/OBJECTIVE: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/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 Vivadent 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 Vivadent 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 posthoc 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.

OBJECTIVES/OBJECTIVE:This study aims to evaluate the opalescence (OP) and color stability of composite resins over a period of 180 days and to compare composite resins' OP with enamel's OP. MATERIALS AND METHODS/METHODS:Twenty human enamel specimens (5.0 × 0.3 mm) and 9 specimens (10.0 × 1.0 mm) of 10 colors of 4 different composite resins (3 M ESPE, FGM, Ivoclar-Vivadent, Miscerium) and one brand of adhesive (3 M ESPE) were made. The results were obtained by measuring the reflectance and transmittance spectra in the visible region. After baseline measurement, composites and adhesive were analyzed after 2, 7, 30, 60, 120, and 180 days. The Lab color coordinates were used in the calculations of the OP parameter and color differences in the CIELab and CIEDE2000 methods. The data were analyzed statistically. RESULTS:The materials tested showed variation and an increase in OP over time. The OP found for enamel was 18.06 ± 2.99, and some resins showed higher results. There was a strong correlation between the coordinate b*T and the OP over time. Enamel Plus was the only one material that presented no color changes during all periods in both color analyses. Filtek Z350 XT, AT, and BT did not show differences in any time when analyzed by CIELAB. CONCLUSIONS:The OP of most composite resins changed during the period of 180 days and was different from the OP of tooth enamel. In general, composites demonstrated small color changes over the period tested, being this characteristic material dependent. CLINICAL RELEVANCE/CONCLUSIONS:Natural teeth present different optical properties. Composite resins restorations should present properties similar to natural teeth and it is important that characteristics like color and opalescence remain stable over time.

OBJECTIVES/OBJECTIVE:To compare the operative time and presence of air voids on Class II restorations fabricated by dental practitioners with 1 to 5 years of experience using incremental and bulk-filling techniques. METHOD AND MATERIALS/METHODS:Four techniques were evaluated: incremental, bulk-filling, bulk-filling with heated composite, and snowplow technique. Standardized mandibular first molars with a MOD (mesial, occlusal, and distal) cavity were used. Voluntary operators made two restorations using each technique and the time required for each restoration was recorded. The restorations were scanned by micro-computed tomography to calculate the volume of the restoration occupied by air voids. The "operative time" and "volume of air voids" were analyzed individually by two-way ANOVA and Tukey HSD post hoc (α = .05) for the factors operator and insertion technique. A correlation between "operative time" and "volume of air voids" was evaluated using Pearson coefficient (α = .05). RESULTS:The incremental technique required significantly longer time, yet no differences were observed between the bulk-filling techniques. There were no significant differences between techniques regarding the volume of air voids. A significant, but weak, and inverse linear correlation (P = .0059; r = -.29; r2 = 8.41%) was found between the operative time and volume of air voids. CONCLUSION/CONCLUSIONS:There were no significant differences in the volume of air voids among the evaluated techniques, although bulk-filling techniques required a shorter operative time. Hence, implementing bulk-filling techniques by dental schools and restorative dental practitioners with different levels of expertise may reduce chair time and produce a volume of air voids similar to the incremental technique.