Color match analysis of single-shade and multi-shade composite resins using spectrophotometric and visual methods after bleaching.

The aim of this study is to evaluate the color match of the materials after the staining and bleaching procedures applied to the teeth restored with single-shade and multi-shade composite resins. Cavities prepared on the facial surface of human incisors were restored with two different composite resins. After 24 h, the color matching parameters between the initial filling-tooth of the samples were recorded. Then, the color measurements of the samples subjected to the coloring process were repeated. Each composite resin group was randomly divided into 2 subgroups and home and office bleaching methods were applied to the samples. After bleaching, color measurements were repeated. In terms of periods, a statistically significant difference was found in ΔE values 1 day and 28 days after bleaching (p<0.05). In addition, it was found that the color match between filling-tooth was generally weaker in Omnichroma material and after home bleaching.

The chameleon effect in customer relationship management: Experiments on the spillover effects of mimicry in natural settings of a chain hotel and a chain grocery shop.

Numerous experiments have proven that mimicry is highly beneficial (mainly to the mimicker but also to the mimickee). Some studies have shown initial data suggesting the potential of applying this knowledge to business settings. In the present paper we unpack this issue in two ways. First, by presenting potential benefits stemming from mimicry for the mimicking dyad, and second for the business environment represented by the mimicker. Two consecutive studies: a Pretest and a Main Experiment run in natural settings showed great potential in improving the assessments of quality of service provided by verbally mimicking (or not). The results of both studies showed that mimicry offers benefits for the mimicker (increased employee kindness and employee evaluation), and also spillover to the organization/company represented by the mimicking employee (increased opinion of and willingness to return to the shop/hotel). Future research directions and limitations are discussed.

Social Isolation Affects the Mimicry Response in the Use of Smartphones : An Ethological Experiment during the COVID-19 Pandemic.

Humans are social animals that rely on different ways to interact with each other. The COVID-19 pandemic strongly changed our communication strategies. Because of the importance of direct contact for our species, we predict that immediately after the forced social isolation, people were more prone to engage in direct rather than in virtual interactions, thus showing a lower mimicry response in the use of smartphones. In a non-longitudinal study, we collected behavioral data under naturalistic contexts and directly compared the data of the mimicry response gathered immediately following the Italian lockdown (May-September 2020) with those gathered one year later (May-October 2021). Contrary to our expectations, the mimicry response in the use of smartphones was higher immediately after the lockdown than a year later. Probably the large use of these devices during the lockdown translated into a greater sensitivity to be affected by others' smartphone manipulation. Indeed, social isolation modified, at least in the short term, the ways we interact with others by making us more prone to engage in "virtual" social interactions. The bright side of the coin unveiled by our findings is that the effect seems to diminish over time. The large behavioral dataset analyzed here (1,608 events; 248 people) also revealed that the mimicry response in the use of smartphones was higher between familiar subjects than between strangers. In this view, mimicry in manipulating smartphones can be considered an example of joint action that fosters behavioral synchrony between individuals that, in the long-term, can translate into the formation of social bonding.

Instrumental and visual evaluation of the color adjustment potential of different single-shade resin composites to human teeth of various shades.

OBJECTIVE: The study aims to evaluate the color adjustment potential (CAP-I, CAP-V) of different single-shade resin composites. MATERIALS AND METHODS: The shades of 40 human incisors were determined using a spectrophotometer, with the teeth divided into four groups of the same shade (n = 10). The following single-shade resin composites were tested: Omnichroma, Charisma Diamond One, Vittra Unique, and Essentia Universal. The specimens were prepared as "dual" and "single." Standardized cavity preparations (diameter, 7 mm; depth, 2 mm) were prepared in human incisor teeth and then restored for dual specimens. Composite duplicates of human incisors were prepared with resin composites for single specimens (n = 10). The color match of these specimens to that of unrestored human incisors was compared, and the color difference (ΔE*) was calculated. Independent observers conducted a visual evaluation of the specimens and scored them. CAP-I and CAP-V values were determined. A one-way analysis of variance test was used for statistical analysis (p < 0.05). RESULTS: There was no statistically significant difference between the CAP-V and CAP-I values of the tested single-shade resin composites (p > 0.05). All the materials tested had acceptable color-matching potential. CONCLUSIONS: In terms of color matching, there were no significant differences between the different tooth shades of all the tested resin composites. CLINICAL RELEVANCE: Single-shade resin composites have acceptable CAP. The use of single-shade resin composites can reduce in-chair clinical times by minimizing the time spent on shade selection.

Color adjustment potential of resin composites: Optical illusion or physical reality, a comprehensive overview.

OBJECTIVE: The objective was to provide a comprehensive overview of color interactions between resin composite (RC) and its surroundings, analyze the design and results of respective research studies, and provide clinical and research recommendations. OVERVIEW: Resin composite (RC) materials can adjust their color to that of surrounding enamel and dentin to a different extent. This phenomenon has been referred to as the "chameleon effect" in dental jargon, while color blending/adjustment/shifting/assimilation is more scientific terms. Studies that evaluated the color adjustment potential of RCs have employed different methods. This article discusses the (a) terminology used to describe color adjustment potential, (b) color science theories associated with color adjustment, (c) design of respective studies, including methods, specimens, and calculations, and (d) their outcome and reported results. Clinical implications and future directions related to the color adjustment potential of RCs are also provided. CONCLUSIONS: Factors that influence the color adjustment potential of RCs are classified into three categories: (1) material type, (2) cavity design, and (3) the substrate surrounding the restoration. Each factor can be optimized to enhance color matching and the restorative outcome. CLINICAL SIGNIFICANCE: A material that blends well and exhibits pronounced color adjustment potential would likely improve the color match and therefore the esthetic outcome. These materials "work" for dental professionals by compensating for their suboptimal shade matching and/or lack of an excellent match in the used material. This review aims to further the understanding of the inherent properties of RCs and allow clinicians to fully utilize them to place RC restorations and minimize the time spent on modifying or replacing existing ones. Hence, the outcomes would encompass the increased chairside efficiency, enhanced esthetic outcome, and patient satisfaction.

The effect of refractive index of fillers and polymer matrix on translucency and color matching of dental resin composite.

OBJECTIVE: When restorative resin composites absorb light from the surrounding tooth structures, it creates a color-match, which is known as 'a chameleon effect'. In this study, series of co-monomer mixtures were prepared with an increasing refraction index (RI) and mixed with glass fillers. The aim of this study was to optimize the mismatch of RI of resin/fillers to create the chameleon effect. MATERIALS AND METHODS: BisGMA/TEGDMA resins were prepared with seven different mix fractions from 20 to 80%. Two different series (A&B) of submicron (Ø 0.7 µm) silanized fillers (70 wt%) (A: Schott RI = 1.53, B: Esschem RI = 1.54) were mixed with resins (30 wt%). Disc-shaped specimens (1 mm thickness, Ø10 mm) for each composite combination (n = 3) were prepared and light cured for 20 s. Commercial resin composite (OmniChroma, Tokuyama Dental) was used as control. The translucency parameter (TP) was measured using a spectrophotometer. The color matching abilities of the experimental composites were visually analyzed. Data were statistically analyzed using ANOVA. RESULTS: The composition of resin and type of fillers had a statistically significant effect on TP values (p < .05). The highest TP values were achieved around 50%-50% fractions of Bis-GMA and TEGDMA for series A and around 60%-40% fraction of Bis-GMA and TEGDMA for series B. Data showed that a high or low fraction of BisGMA resulted in a low translucent composite. Experimental resin composite (80% Bis-GMA) from series A was behaving similarly to Omnichroma in reference to TP values and color matching. CONCLUSIONS: Including fillers with RI of 1.53 into BisGMA/TEGDMA resin with RI of 1.524 resulted in composite resin providing a good color match with surrounding structure 'chameleon effect'.

The Reverse Chameleon Effect: Negative Social Consequences of Anatomical Mimicry.

Bodily mimicry often makes the mimickee have more positive feelings about the mimicker. Yet, little is known about the causes of mimicry's social effects. When people mimic each other's bodily movements face to face, they can either adopt a mirrorwise perspective (moving in the same absolute direction) or an anatomical perspective (moving in the same direction relative to their own bodies). Mirrorwise mimicry maximizes visuo-spatial similarity between the mimicker and mimickee, whereas anatomical mimicry maximizes the similarity in the states of their motor systems. To compare the social consequences of visuo-spatial and motoric similarity, we asked participants to converse with an embodied virtual agent (VIRTUO), who mimicked their head movements either mirrorwise, anatomically, or not at all. Compared to participants who were not mimicked, those who were mimicked mirrorwise tended to rate VIRTUO more positively, but those who were mimicked anatomically rated him more negatively. During face-to-face conversation, mirrorwise and anatomical mimicry have opposite social consequences. Results suggest that visuo-spatial similarity between mimicker and mimickee, not similarity in motor system activity, gives rise to the positive social effects of bodily mimicry.

Postural Stabilization Strategies to Motor Contagion Induced by Action Observation Are Impaired in Parkinson's Disease.

Postural reactions can be influenced by concomitant tasks or different contexts and are modulated by a higher order motor control. Recent studies investigated postural changes determined by motor contagion induced by action observation (chameleon effect) showing that observing a model in postural disequilibrium induces an increase in healthy subjects' body sway. Parkinson's disease (PD) is associated with postural instability and impairments in cognitively controlled balance tasks. However, no studies investigated if viewing postural imbalance might influence postural stability in PD and if patients are able to inhibit a visual postural perturbation. In this study, an action observation paradigm for assessing postural reaction to motor contagion in PD subjects and healthy older adults was used. Postural stability changes were measured during the observation of a static stimulus (control condition) and during a point-light display of a gymnast balancing on a rope (biological stimulus). Our results showed that, during the observation of the biological stimulus, sway area and antero-posterior and medio-lateral displacements of center of pressure significantly increased only in PD participants, whereas correct stabilization reactions were present in elderly subjects. These results demonstrate that PD leads to a decreased capacity to control automatic imitative tendencies induced by motor contagion. This behavior could be the consequence either of an inability to inhibit automatic imitative tendencies or of the cognitive load requested by the task. Whatever the case, the issue about the ability to inhibit automatic imitative tendencies could be crucial for PD patients since it might increase falls risk and injuries.

Quantum probability and Hilbert's sixth problem.

With the birth of quantum mechanics, the two disciplines that Hilbert proposed to axiomatize, probability and mechanics, became entangled and a new probabilistic model arose in addition to the classical one. Thus, to meet Hilbert's challenge, an axiomatization should account deductively for the basic features of all three disciplines. This goal was achieved within the framework of quantum probability. The present paper surveys the quantum probabilistic axiomatization.This article is part of the themed issue 'Hilbert's sixth problem'.

Gaze leading is associated with liking.

Gaze plays a pivotal role in human communication, especially for coordinating attention. The ability to guide the gaze orientation of others forms the backbone of joint attention. Recent research has raised the possibility that gaze following behaviors could induce liking. The present study seeks to investigate this hypothesis. We designed two physically different human avatars that could follow the gaze of users via eye-tracking technology. In a preliminary experiment, 20 participants assessed the baseline appeal of the two avatars and confirmed that the avatars differed in this respect. In the main experiment, we compared how 19 participants rated the two avatars in terms of pleasantness, trustworthiness and closeness when the avatars were following their gaze versus when the avatar generated gaze movements autonomously. Although the same avatar as in the preliminary experiment was rated more favorably, the pleasantness attributed to the two avatars increased when they followed the gaze of the participants. This outcome provides evidence that gaze following fosters liking independently of the baseline appeal of the individual.

Mimicry and expressiveness of an ECA in human-agent interaction: familiarity breeds content!

BACKGROUND: Two experiments investigated the effect of features of human behaviour on the quality of interaction with an Embodied Conversational Agent (ECA). METHODS: In Experiment 1, visual prominence cues (head nod, eyebrow raise) of the ECA were manipulated to explore the hypothesis that likeability of an ECA increases as a function of interpersonal mimicry. In the context of an error detection task, the ECA either mimicked or did not mimic a head nod or brow raise that humans produced to give emphasis to a word when correcting the ECA's vocabulary. In Experiment 2, presence versus absence of facial expressions on comprehension accuracy of two computer-driven ECA monologues was investigated. RESULTS: In Experiment 1, evidence for a positive relationship between ECA mimicry and lifelikeness was obtained. However, a mimicking agent did not elicit more human gestures. In Experiment 2, expressiveness was associated with greater comprehension and higher ratings of humour and engagement. CONCLUSION: Influences from mimicry can be explained by visual and motor simulation, and bidirectional links between similarity and liking. Cue redundancy and minimizing cognitive load are potential explanations for expressiveness aiding comprehension.

Distinct neural processes are engaged in the modulation of mimicry by social group-membership and emotional expressions.

People often spontaneously engage in copying each other's postures and mannerisms, a phenomenon referred to as behavioral mimicry. Social psychology experiments indicate that mimicry denotes an implicit affiliative signal flexibly regulated in response to social requirements. Yet, the mediating processes and neural underpinnings of such regulation are largely unexplored. The present functional magnetic resonance imaging (fMRI) study examined mimicry regulation by combining an automatic imitation task with facial stimuli, varied on two social-affective dimensions: emotional expression (angry vs happy) and ethnic group membership (in- vs out-group). Behavioral data revealed increased mimicry when happy and when out-group faces were shown. Imaging results revealed that mimicry regulation in response to happy faces was associated with increased activation in the right temporo-parietal junction (TPJ), right dorsal premotor cortex (dPMC), and right superior parietal lobule (SPL). Mimicry regulation in response to out-group faces was related to increased activation in the left ventral premotor cortex (vPMC) and inferior parietal lobule (IPL), bilateral anterior insula, and mid-cingulate cortex (MCC). We suggest that mimicry in response to happy and to out-group faces is driven by distinct affiliative goals, and that mimicry regulation to attain these goals is mediated by distinct neuro-cognitive processes. Higher mimicry in response to happy faces seems to denote reciprocation of an affiliative signal. Higher mimicry in response to out-group faces, reflects an appeasement attempt towards an interaction partner perceived as threatening (an interpretation supported by implicit measures showing that out-group members are more strongly associated with threat). Our findings show that subtle social cues can result in the implicit regulation of mimicry. This regulation serves to achieve distinct affiliative goals, is mediated by different regulatory processes, and relies on distinct parts of an overarching network of task-related brain areas. Our findings shed new light on the neural mechanisms underlying the interplay between implicit action control and social cognition.