An Fmri Study on Self-Perception of Patients After Aesthetic Implant-Prosthetic Rehabilitation

International Journal of Environmental Research and Public Health

Article An fMRI Study on Self-Perception of Patients after Aesthetic Implant-Prosthetic Rehabilitation

Francesca Cattoni 1,2 , Giulia Tetè 2,3, Riccardo Uccioli 1,2,*, Fabio Manazza 1, Giorgio Gastaldi 1,4 and Daniela Perani 5

1 Dental School, Vita-Salute San Raffaele University, 20121 Milan, Italy; [email protected] (F.C.); [email protected] (F.M.); [email protected] (G.G.) 2 Department of Dentistry, IRCCS San Raffaele Hospital, 20121 Milan, Italy; [email protected] 3 Specialization School in Oral Surgery, Vita Salute San Raffaele University, 20121 Milan, Italy 4 Unit of Oral Maxillofacial Surgery, San Rocco Clinical Institute, Ome, 25050 Brescia, Italy 5 Department of Nuclear Medicine and Division of Neuroscience, Vita Salute San Raffaele University, San Raffaele University, 20121 Milan, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-34-7344-3280

Received: 25 November 2019; Accepted: 11 January 2020; Published: 16 January 2020

Abstract: Objectives: In this functional magnetic resonance (fMRI) study, we investigated the activation of cerebral pathways involved in the elaboration of self-retracting photos (SELF) and the same pictures of others (OTHER). Each of the photographs showed one of the participants during different stages of the rehabilitation: pre-treatment (PRE), virtual planning using “Smile-Lynx” smile design software (VIR), and post-rehabilitation (POST). Methods: We selected eighteen volunteers, both male and female, between 22 and 67 years of age, who previously underwent prosthetic rehabilitation. Each of them was subjected to an fMRI acquisition. Various stimuli were then shown to the subjects in the form of self-retracting photographs and photographs of other participants, all in pseudo-randomized order. We then carried out a two- stage mixed-effects group data analysis with statistical contrast targeting two main effects: one regarding the main effect of Identity (SELF vs. OTHER) and the other regarding the effect of the prosthetic rehabilitation phase (PRE vs. VIR vs. POS). All the effects mentioned above survived a peak-level of p < 0.05. Results: For the effect of identity, results reported the involvement of dorsolateral frontoparietal areas bilaterally. For the phase by identity effect, results reported activation in the supplementary motor area (SMA) in the right hemisphere. A stronger activation in observing self-retracting photos (SELF) post-treatment (POST) was reported compared to the other phases considered in the experiment. Conclusions: All the collected data showed differences regarding the main effect of Identity (SELF vs. OTHER). Most importantly, the present study provides some trend-wise evidence that the pictures portraying the subject in their actual physiognomy (POST) have a somewhat special status in eliciting selectively greater brain activation in the SMA. This effect was interpreted as a plausible correlate of an empathic response for beautiful and neutral faces. The present research suggests a possible way to measure self-perception of the subject after an appearance-altering procedure such an implant-prosthetic rehabilitation. However, future clinical studies are needed to investigate this matter further.

Keywords: dental implant; prosthodontics; digital dentistry; aesthetic dentistry; mock up; fMRI

1. Introduction Achieving an aesthetically pleasing ﬁnal result is one of the most crucial goals of a successful dental prosthetic rehabilitation since the location and the number of missing teeth is an important factor aﬀecting the quality of life [1]; This often requires a multidisciplinary approach consisting of

Int. J. Environ. Res. Public Health 2020, 17, 588; doi:10.3390/ijerph17020588 www.mdpi.com/journal/ijerph Int. J. Environ. Res. Public Health 2020, 17, 588 2 of 8 the teamed-up work of different professionals such as prosthodontists, oral surgeons, prosthodontist periodontists, and dental technicians [2]. Thanks to the fast advances in technology, it is now easier to obtain an excellent outcome for the treatment, leaving the patient satisfied. It is also very convenient to visualize the outcome in advance with the aid of rendering software such as Smile Lynx (3D Lynx, Varese, Italy). These kinds of software can process different pictures of the patients, helping the clinician to trace guidelines for facial, dental, and gingival analysis, finally producing a digital pre-visualization of the final result [3]. Once the work is pre-viewed and the treatment accepted, the patients undergo different dental procedures. Such operations include the filing of selected teeth and the placement of single or multiple implants as a support for a prosthetic device. Every step of the treatment should be performed in the least invasive way possible to preserve the majority of the dental substance and to reduce healing times [4]. The prosthetic devices were produced based on both traditional and digital oral impressions. Both types of impressions are considered valid and accurate, even though the digital workflow is known to be less invasive [5]. At the end of the treatment, it is common to notice an improvement in patients’ self-perception and a consequent increase in beauty and confidence [6]. However, this kind of transformation is often self-reported and empirical. New analytic protocols based on the use of functional magnetic resonance (fMRI) allow clinicians from every field of medicine to investigate all the different activations and responses of the brain to external stimuli [7]. This research aims to evaluate the various neural patterns activations in patients at the end of their prosthetic rehabilitation, trying to interpret the results referencing findings already published in the literature.

2. Materials and Methods

2.1. Subjects (Protocol Viscon-01) Eighteen patients: 8 men and 10 women, with a range of ages between 22 and 67 years, were randomly selected from a group of patients who completed the treatment in the year before the beginning of this study. The selected subjects met the following inclusion criteria: they were all older than 20 years old, all reported general good health and all had previously undergone prosthetic dental rehabilitation supported both by natural teeth and implants. In the latter case, implants had been placed both on edentulous and non-edentulous dental arches. Winsix Implants (Biosafin, Ancona, Italy) were used to execute all the various rehabilitations both in the maxilla and in the mandibular bone. Implants were placed both in the anterior and in the posterior areas of the dental arches. The fMRI acquisitions of three subjects (all female, aged 67, 65, and 53) revealed unexpected cerebral vascular lesions, which, however, were not associated with cognitive impairment, as assessed by an extensive neuro-psychological test battery. It was therefore considered appropriate to retain these subjects within the experimental sample. Since the aim of the study was to investigate the selective activation of any specific areas in the brain following the submission of both self-retracting pictures and non-self-retracting pictures, we formulated a null hypothesis. This null hypothesis stated that there is not any specific cerebral pathway activation when it comes to the elaboration of self-retracting photos or photos of others.

2.2. Neuropsychological Battery Before the fMRI acquisition session, all volunteers underwent a neuropsychological assessment. Due to the quite large age range of our sample, the objective of this evaluation was to exclude the presence of individuals with cognitive functions below the normality level. The assessment batteries and tests included the Edinburgh Handedness Inventory [8], the Mini Mental State Examination Test [9] the Digit Span [10], in both the forward and backward versions, and a semantic verbal ﬂuency test cued by semantic category labels. Int. J. Environ. Res. Public Health 2020, 17, 588 3 of 8

Int. J. Environ. Res. Public Health 2020, 17, x FOR PEER REVIEW 3 of 9 2.3. Stimuli 2.3. Stimuli The stimuli used were photographs depicting each subject included in the experiment (Figure1). The stimuli used were photographs depicting each subject included in the experiment (Figure The1). photos The photos taken taken into into consideration consideration portrayed portrayed the the various various subjectssubjects before prosthetic prosthetic rehabilitation rehabilitation (PRE),(PRE), during during the the virtual virtual planning planning of of the the smile smile inin the Smile Lynx Lynx software software (VIR) (VIR),, and and after after completing completing thethe rehabilitation rehabilitation (POST). (POST). For For each each of of these these phases, phases, two two photographs photographs of of the the patient patient were were collected; collected; the ﬁrstthe one first depicting one depicting the patient the patient in a frontal in a frontal position position (FR), (FR), and theand secondthe second one one showing showing the the middle middle third of thethird face, of the i.e., face, the smilei.e., the in smile the esthetic in the esthetic zone (MT); zone the(MT); subject the subject was then was exposed then exposed to a total to a oftotal 198 of stimuli 198 throughoutstimuli throughout the duration the duration of the acquisition. of the acquisition. Each pictureEach picture was was presented presented for for a duration a duration of of 2000 2000 ms duringms during the fMRI the visualfMRI visual stimulation, stimulation, with awith variable a variable inter-stimulus inter-stimulus interval int durationerval duration between between 3 and 3 7 s. Forand each 7 s. patient, For each the patient, set of the 6 self-retracting set of 6 self-retracting photos photos (Figure (Figure1) was 1) presented was presented 4 times 4 times over theover entire the fMRIentire study, fMRI whereas study, wher the pictureseas the pictures of others of were others each were presented each presented only once. only This once. decision This decision was made was to ensuremade that to ensure the subjects that the would subjects familiarize would familiarize themselves themselves with their with picture, their picture, thus providing thus providing an accurate an reactionaccurate and reaction consistent and neuralconsistent pattern neural activation pattern activation for the analysis for the ofanalysis the main of t eheﬀ ectmain of theeffect prosthetic of the rehabilitationprosthetic rehabilitation phase. The entire phase. set The of stimuli entire wasset of divided stimuli in was two divided halves, inwhich two were halves, presented which were in two separatepresented fMRI in acquisitiontwo separate runs, fMRI each acquisition lasting runs, approximately each lasting 10 approximately minutes. Each 10 fMRIminutes. run, Each in addition fMRI to therun, experimental in addition to pictures, the experimental included 10 pictures, null events, included in order 10 null to maximize events, in the order hemodynamic to maximize signal the hemodynamic signal sensitivity of the event-related design. sensitivity of the event-related design.

Figure 1. Standard set of participants’ photos: Photos of one of the participant’s portrait in the three phasesFigure of 1. the Standard treatment set of (from participants’ above PRE–VIR–POST). photos: Photos of one Each of phasethe participant was featured’s portrait by twoin the di threeﬀerent photographs:phases of the one treatment showing (from the patient above in PRE frontal–VIR– positionPOST). Each (left column),phase was and featured one showing by two the different middle thirdphotographs: of the patient’s one showing face (right the column).patient in frontal position (left column), and one showing the middle third of the patient’s face (right column). 2.4. Factors Taken into Consideration 2.4. Factors Taken into Consideration The experimental design reﬂected a 2 3 factorial combination, as follows: × The experimental design reflected a 2 × 3 factorial combination, as follows: - IDENTITY FACTOR: with the two levels SELF and OTHER. - IDENTITY FACTOR: with the two levels SELF and OTHER. - PHASE FACTOR: with levels PRE, VIR, and POST. - PHASE FACTOR: with levels PRE, VIR, and POST. 2.5. Experimental Tasks The presentation of the stimuli and the recording of the responses was performed using an experiment control software called Presentation® 20.0 (Neurobehavioral Systems Inc., Albany, CA,

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USA) [11]. Subjects were requested to perform a task, which consisted in pressing a button every time a green-bordered photo appeared. These green-coded catch trials represented 15% of the total number of the stimuli, and were randomly interspersed within the stimulation sequence. The corresponding hemodynamic events were modeled as a confounding variable and were therefore excluded from the analysis of the experimental eﬀects of interest. Before the experimental fMRI runs, a brief fMRI training session was administered to each participant, in order to verify that the participant complied with the task instructions and requests.

2.6. fMRI Data Acquisition Magnetic resonance scans were acquired using a 3T Ingenia Philips scanner (Philips, Amsterdam, The Netherlands). The functional images were obtained with an echo-planar T2* sequence. Each functional image includes 34 contiguous axial sections with 4 mm thickness acquired in ascending interleaved mode, with a repetition time of 2000 ms (echo time: 30 ms, field of view: 240 240 mm, matrix size: 96 96, rotation angle 85 ). Each participant was subjected to 2 functional × × ◦ acquisition sessions. The duration of both sessions was 560 s, corresponding to 280 scans each. To allow for stabilization of the magnetic field, both sessions were preceded by 5 empty scans, which were eliminated before proceeding with the data analysis. For anatomical localization and visualization of brain activations, a high-resolution structural scan weighed in T1 was performed, with a repetition time of 7.1 ms (echo time: 3.5 ms; resolution: 0.7mm 0.7 mm 0.7 mm). × × 2.7. fMRI Data Analysis The “Statistical Parametric Mapping” software (Wellcome Centre for Human Neuroimaging, London, UK) [12] was used for preprocessing and statistical analysis of the fMRI data [13]. Functional images were corrected for slice timing and spatially realigned. The images were normalized to the Montreal Neurological Institute standard (MNI) space, using the Segment procedure with the subject-specific segmented structural images as customized segmentation priors. Finally, the images were spatially smoothed with an 8 mm Full width at half maximum (FWHM) Gaussian kernel. We adopted a two-level statistical approach with mixed-effects to enable result generalization at the population level. Statistical analysis was restricted to an explicit mask that included only voxels with gray matter tissue probability >0.1, based on the structural images of each participant. At the first level of analysis, the time series of each participant were filtered with a 128 s high-pass filter and with an AR [14] autoregressive model. No global normalization was performed. The hemodynamic response evoked by each experimental stimulus was modeled with a canonical hemodynamic response function [15]. We modeled two separate sessions, each including 6 regressors of interest (SELF–PRE, SELF–VIR, SELF–POS, OTHER–PRE, OTHER–VIR, OTHER–POST), with evoked responses aligned to the onset of each trial, and a duration of 2000 ms (Table1). Separate regressors modeled experimental sounds, including catch trials, task instructions, and head movement realignment parameters.

Table 1. Activation of supplementary motor area (SMA): Activations for the identity phase interaction × (OTHER/SELF vs. PRE/POS).

Brain Region Voxels p-Value Z MNI Coordinates (mm) 10 R Posterior-Medial Frontal (SMA) 1 0.09 4.5 10 0 76

For each subject, the following first level Student’s t-test contrasts were defined: c1-1. Main effect of Identity (SELF vs. OTHER). Contrast weights for [SELF–PRE, SELF–VIR, SELF–POST, OTHER–PRE, OTHER–VIR, OTHER–POST]: [+1 +1 +1 1 1 1]. − − − c1-2. Simple effect of Phase PRE vs. VIR. Contrast weights: [+1 1 0 +1 1 0]. − − c1-3. Simple effect of Phase PRE vs. POST. Contrast weights: [+1 0 1 +1 0 1]. − − Int. J. Environ. Res. Public Health 2020, 17, 588 5 of 8 Int. J. Environ. Res. Public Health 2020, 17, x FOR PEER REVIEW 5 of 9 c1-4.c1 Simple-3. Simple eff ecteffect of Phaseof Phase PRE PRE vs. vs VIR. POST. for SELFContrast (SELF–PRE weights: vs.[+1 SELF–VIR).0 −1 +1 0 −1]. Contrast weights: [+1 1 − c10-4. 0 Simple 0 0]. effect of Phase PRE vs. VIR for SELF (SELF–PRE vs. SELF–VIR). Contrast weights: [+1 −1 0 0 0 0]. c1-5. Simple effect of Phase PRE vs. VIR for OTHER (OTHER–PRE vs. OTHER–VIR). Contrast weights: c1-5. Simple effect of Phase PRE vs. VIR for OTHER (OTHER–PRE vs. OTHER–VIR). Contrast [0 0 0 +1 1 0]. weights:− [0 0 0 +1 −1 0]. c1-6.c1Simple-6. Simple eff effectect of of Phase Phase PRE PRE vs. vs. POST POST for for SELF SELF (SELF–PRE(SELF–PRE vs.vs. SELF SELF–POST).–POST). Contrast Contrast weights: weights: [+1 0 1 0 0 0]. [+1− 0 −1 0 0 0]. c1-7.c1Simple-7. Simple eff effectect of of Phase Phase PRE PRE vs. vs. POST POST for for OTHER OTHER (OTHER–PRE (OTHER–PRE vs.vs. OTHER OTHER–POST).–POST). Contrast Contrast weights:weights: [0 [0 0 00 +0 1+1 0 0 −1].1]. − At theAt the second second stage stage of analysis,of analysis, the the contrast contrast images images obtained obtained at theat the first first level level were were included included in in the followingthe following mixed-e mixedffects-effects models: models: c2-1. Main effect of Identity (SELF vs. OTHER): one-sample t-test over c1-1 contrasts. c2-1.c2Main-2. Main eff ecteffect of of Identity Phase (PRE (SELF vs. vs. VIR OTHER): vs. POST): one-sample two-samplet-test t-test over over c1-1 c1- contrasts.2 and c1-3 contrasts. c2-2.c2Main-3. Identity effect by of Phase Phase (PRE interaction vs. VIR (SELF/OTHER vs. POST): two-sample vs. PRE/VIR):t-test paired over c1-2t-test and over c1-3 c1 contrasts.-4 and c1-5 c2-3. Identitycontrasts. by Phase interaction (SELF/OTHER vs. PRE/VIR): paired t-test over c1-4 and c1-5 contrasts. c2-4.c2Identity-4. Identity by by Phase Phase interaction interaction (SELF(SELF/OTHER/OTHER vs. vs. PRE/POST: PRE/POST: paired paired t-testt -testover overc1-6 and c1-6 c1 and-7 c1-7contrasts. contrasts. All the reported effects survived a declared peak-level p < 0.05, using a small volume Family All the reported effects survived a declared peak-level p < 0.05, using a small volume Family Wise Wise Error (FWE) type correction for multiple comparisons. Error (FWE) type correction for multiple comparisons. 3. Results 3. Results 3.1. Main Effect of Identity 3.1. Main Effect of Identity Significant activations were found for both levels of the Identity factor (Figure 2). Greater Significant activations were found for both levels of the Identity factor (Figure2). Greater activation activation for SELF versus OTHER was found bilaterally in the dorso-lateral fronto-parietal cortex, for SELF versus OTHER was found bilaterally in the dorso-lateral fronto-parietal cortex, and in the and in the occipito-temporal cortex, including in particular the fusiform gyrus. In turn, OTHER occipito-temporalsignificantly activated cortex, more including than inSELF particular the bilateral the fusiform sensorimotor gyrus. cortices, In turn, the OTHER superior significantly temporal activatedgyrus, and more the than insula. SELF the bilateral sensorimotor cortices, the superior temporal gyrus, and the insula.

Figure 2. Barplot of mean or standard error, identity by phase interaction effect (SELF/OTHER vs. ± PREFigure/POS). 2. Barplot of mean ± or standard error, identity by phase interaction effect (SELF/OTHER vs. PRE/POS). 3.2. Main Effect of Phase 3.2. Main Effect of Phase No significant activations were found. No significant activations were found. 3.3. Identity by Phase Interaction (Self /Other vs. PRE/VIR) No significant activations were found.

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3.3. Identity by Phase Interaction (Self/Other vs. PRE/VIR) Int. J.No Environ. significant Res. Public activations Health 2020, 17were, 588 found. 6 of 8

3.4. Identity by Phase Interaction (Self/Other vs. Pre/Post) 3.4. Identity by Phase Interaction (Self/Other vs. Pre/Post) A trend-wise activation effect was found in the supplementary motor area (SMA) of the right A trend-wise activation eﬀect was found in the supplementary motor area (SMA) of the right hemisphere (Figure 3). This interaction effect was mainly explained by a selective increase in brain hemisphere (Figure3). This interaction e ﬀect was mainly explained by a selective increase in brain activation for SELF pictures after the intervention (POST). activation for SELF pictures after the intervention (POST).

Figure 3. Various Activations: (above) Activation of the dorso-lateral fronto-parietal cortex and Figure 3. Various Activations: (above) Activation of the dorso-lateral fronto-parietal cortex and occipital-temporal cortex for the main effect SELF vs. OTHERS and (below) bilateral sensor motor occipital-temporal cortex for the main effect SELF vs. OTHERS and (below) bilateral sensor motor cortices, the superior temporal gyrus, and the insula for OTHER vs. SELF. cortices, the superior temporal gyrus, and the insula for OTHER vs. SELF. 4. Discussion 4. Discussion The results of this fMRI study concerning the visual apperception of self-retracting face pictures versusThe pictures results of of this others’ fMRI facesstudy confirmconcerning the the observations visual apperception of a number of self- ofretracting previous face studies pictures in versusthe literature pictures [16 of– 18others’], in showing faces confirm a greater the involvementobservations of braina number activations of previous in the studies dorso-lateral in the literaturefronto-parietal, [16–18], the in fusiform showing gyrus, a greater the inferiorinvolvement occipito-temporal of brain activations cortices, in and the thedorso insula.-lateral These fronto are- well-knownparietal, the brainfusiform circuits gyrus, displaying the inferior selective occipito self-temporal and other cortices, face-recognition and the insula. responses These [19 ].are Crucial well- knownaspects brainare the circuits involvement displaying of the selective frontoparietal self and motor other system face-recognition and visual associative responses [19].cortex Crucial in the aself-recognitionspects are the involvement and the involvement of the frontoparietal of somatosensory motor and system limbic and system visual for associative the recognition cortex of others.in the self-recognitionMost importantly, and the the involvement present study of somatosensory provides some and trend-wise limbic system evidence for the that, recognition among all of others.self-retracting faces in the different stages of the prosthetic rehabilitation, those portraying the subjectMost in herimportantly,/his actual physiognomythe present study (i.e., theprovides POST stage)some tren haved- awise somewhat evidence special that, status among in elicitingall self- retractingselectively faces greater in the brain different activation stages in theof the supplementary prosthetic rehabilitation, motor area (SMA) those portraying (Figure4). The the observedsubject in her/hisinteraction actual in the physiognomy SMA was accounted (i.e., the for POST by a selectively stage) have greater a somewhat activation specialin observing status self-retracting in eliciting photosselectively (SELF) greate afterr brain the prosthetic activation rehabilitation in the supplementary (POST) versus motor allarea the (SMA) other experimental(Figure 4). The conditions. observed interactionNotably, activation in the SMA in the was SMA accounted for face stimuli for by have a selectively been previously greater found activation in at least in oneobserving fMRIstudy self- retractingon the neural photos correlates (SELF) ofafter aesthetic the prosthetic face apperception rehabilitation [20]. (POST) In that versus study, all this the eff otherect was experimental tentatively conditions.interpreted Notably, as a plausible activation correlate in the of SMA an empathic for face stimuli response have for been beautiful previously and neutral found faces, in at least possibly one fMRIdriving study imagined on the motor neural plans correlates and actions. of aesthetic It is possibleface apperception that the SMA [20] activation. In that study, in the this present effect study was tentativelyis associated interpreted with an analogous as a plausible empathic correlate and of action an empathic response, response which for is beautiful greater for and the neutral recognition faces, possiblyof the self driving in the imagined actual better motor physiognomy plans and actions. state (POST), It is possible and it is that relatively the SMA reduced activation for all in the presentother conditions, study is ass includingociated with self-portraying an analogous pictures empathic before and theaction intervention response, which and pictures is greater of for others. the Therecognition type of rehabilitationof the self in the should actual be better alsobe physiognomy taken into consideration. state (POST), aand recent it is systematicrelatively reduced review and for meta-analysis of the literature conducted by Fueki and Baba in 2018 [1] stressed the fact that patients with implant-supported fixed partial dental prosthesis exhibit better quality of life, even though when Int. J. Environ. Res. Public Health 2020, 17, x FOR PEER REVIEW 7 of 9 all the other conditions, including self-portraying pictures before the intervention and pictures of others. The type of rehabilitation should be also be taken into consideration. a recent systematic review and meta-analysis of the literature conducted by Fueki and Baba in 2018 [1] stressed the fact Int. J. Environ. Res. Public Health 2020, 17, 588 7 of 8 that patients with implant-supported fixed partial dental prosthesis exhibit better quality of life, even though when compared with other types of prosthetic rehabilitation, the difference is not statistically comparedsignificant.with The same other work types reported of prosthetic that rehabilitation,the perceived need the di forfference dental is treatment not statistically is associated significant. with Thea quality same of work life reportedimpairment. that theBefore perceived fMRI acquisition need for dental studies, treatment investigations is associated on patients' with a quality perceptio of lifens impairment.of one's personal Before fMRI attractiveness acquisition havestudies, been investigations conducted on throughpatients’ perceptions the submission of one’s of personal paper attractivenessquestionnaires, have written been conductedstatements throughor visual the analog submission scales of [21 paper–23]. questionnaires, These original written methods statements always orpresented visual analog the significant scales [21 limitation–23]. These of being original subjective methods and always entirely presented empirical, the thus significant making limitationit difficult ofto being standardize subjective measurements and entirely andempirical, normalize thus making responses. it di Itffi cult is vital to standardize to also consider measurements the variou ands normalizelimitations responses.of this particular It is vital study, to also one consider of them thebeing various the altered limitations response of this to the particular photos of study, the vi onertual of themplanning being (VIR) the since altered the response output of to the the software photos ofis supposed the virtual to planning give a general (VIR) image since theof the output ideal ofsmi thele softwareof the patients, is supposed while to the give zoomed a general image image used of to the stimulate ideal smile the subject of the patients, lacked in while quality. the Anotherzoomed imagelimitation used involves to stimulate the small the subject number lacked of subjects in quality. taken Another into consideration limitation involves. New theand small more number in-depth of subjectsstudies are taken needed into consideration.to further investigate New and this more topic. in-depth studies are needed to further investigate this topic.

Figure 4. Activation of the SMA: Identity by phase interaction eﬀect (SELF/OTHER vs. PRE/POS).

5. ConclusionsFigure 4. Activation of the SMA: Identity by phase interaction effect (SELF/OTHER vs. PRE/POS). This study is to be considered as one of the first steps towards exploring and understanding human5. Conclusions perception of dental aesthetics. These preliminary data provide important insights for future studiesThis by study suggesting is to be a possible considered neuro-cognitive as one of the measure first steps of how towards the perception exploring of and oneself understanding can vary as ahuman consequence perception of aesthetic of dental prosthetic aesthetics. rehabilitation. These preliminary data provide important insights for future studies by suggesting a possible neuro-cognitive measure of how the perception of oneself can vary Author Contributions: Conceptualization, F.C., F.M., R.U.; G.G., D.P.; methodology, D.P.; software, D.P.; validation, F.M.,as a consequence R.U. and D.P.; of formal aesthetic analysis, prosthetic D.P.; investigation, rehabilitation. F.C., G.T., R.U.; resources, G.T.; data curation, F.M., R.U.; writing—original draft preparation R.U; review and editing, F.C., G.T.; visualization, D.P.; supervision, D.P., G.G.; projectAuthor administration, Contributions: G.G., Conceptualization, F.C. All authors F.C.have, readF.M., and R.U.; agreed G.G. to, D.P.; the published methodology, version D.P.; of the software, manuscript. D.P.; Funding:validation,This F.M., research R.U. and received D.P.; no formal external analysis, funding. D.P.; investigation, F.C., G.T., R.U.; resources, G.T.; data curation, F.M., R.U.; writing—original draft preparation R.U; review and editing, F.C., G.T.; visualization, D.P.; Conflicts of Interest: The authors declare that they have no known competing financial interests or personal relationshipssupervision, D.P. that, couldG.G.; haveproject appeared administration, to influence G.G. the, F.C. work All reported authors in have this read paper. and agreed to the published version of the manuscript. Ethics Approval and Consent to Participate: This study was approved by the ethical board of the IRCCS San RaFunding:ffaele Hospital This research of Milan received (9/INT no/2015). external All patientsfunding. provided their informed consent in writing; they also gave their consent for the use of their facial portrait photos for experimental purposes. The authors declare that the investigationsConflicts of Interest were carried: The authors out following declare the that rules they of have the Declaration no known ofcompeting Helsinki offinancial 1975. interests or personal Availabilityrelationships of that Data could and have Materials: appearedAll to materials influence described the work in reported this manuscript in this paper. including all relevant raw data, will be freely available to any scientist wishing to use them for non-commercial purposes, without breaching participantEthics Approval confidentiality. and Consent to Participate: This study was approved by the ethical board of the IRCCS San Raffaele Hospital of Milan (9/INT/2015). All patients provided their informed consent in writing; they also gave Referencestheir consent for the use of their facial portrait photos for experimental purposes. The authors declare that the investigations were carried out following the rules of the Declaration of Helsinki of 1975. 1. Fueki, K.; Baba, K. Shortened dental arch and prosthetic effect on oral health-related quality of life: AvailabilityA systematic of Data review and Materials and meta-analysis.: All materialsJ. Oral described Rehabil. 2017in this, 44 manuscript, 563–572. [ CrossRefincluding][ allPubMed relevant] raw data, 2.will beLiebermann, freely available A.; Frei, to any S.; Pinheiroscientist wishing Dias Engler, to use M.L.; them Zuhr, for non O.; Prandtner,-commercial O.; pur Edelhoposes,ff ,without D.; Saedi breaching Pour, R. participantMultidisciplinary confidentiality. full-mouth rehabilitation with soft tissue regeneration in the esthetic zone. J. Esthet. Restor. Dent. 2018, 20, 22–29. [CrossRef][PubMed] 3. Smile Lynx-3D Lynx. Available online: http://www.3d-lynx.com/ (accessed on 1 January 2018). Int. J. Environ. Res. Public Health 2020, 17, 588 8 of 8

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