Exploring Digital Gingival Shade Matching in Students

PURPOSE

To study the degree of accuracy in gingival shade matching of undergraduate students using a computer application.

MATERIALS AND METHODS

In total, 76 undergraduate dental students' gingival shade selection abilities were evaluated using an in-house developed computer application. A total of 15 intraoral gingival photographs and 21 pink gingival color porcelain samples were used. The environmental conditions were standardized, and no time limit was set for answering in the computer application.

RESULTS

Fourteen gingival color samples (66.6%) were not useful for representing the studied gingival shades. Not all natural gingival colors studied were represented within the 50.50% acceptability limits of the pink samples. There were no statistically significant differences between men and women in terms of "hit" percentages. The highest correlation coefficient (in absolute value) was for the L* coordinate (the darker the gingiva in the picture, the higher the hit rate for choosing the "ideal" shade tab); however, none of the linear correlation coefficients were statistically significant.

CONCLUSIONS

Not all colors provided in the pink ceramic system were useful for subjective gingival selection. There were no statistically significant differences between male and female dental students in gingival color perception. The L* coordinate was the only one that influenced the correct perception of gingival color by dental students, and it did so more in women than in men.

How do the dimensions of peri-implant mucosa affect marginal bone loss in equicrestal and subcrestal position of implants? A 1-year clinical trial

INTRODUCTION

There is evidence that the apico-coronal implant position and the mucosal phenotype can affect the extent of peri-implant bone loss. This clinical trial analyzes the bone remodeling and marginal bone loss that occur around conical-connection implants placed equicrestally and subcrestally, assessing the effect of the peri-implant soft-tissue phenotype.

METHODS

Fifty-one patients received 56 implants of distinct diameters (3.5 mm Ø n = 6; 4.3 mm Ø n = 41; 5 mm Ø n = 9) in the posterior part of the maxilla or mandible. The implants were placed equicrestally, 1 mm subcrestally and >1 mm subcrestally, depending on the initial supracrestal tissue height (STH). After 3 months of non-submerged healing, single metal-ceramic screw-retained implant-supported crowns were placed. Longitudinal measurements of STH, mucosal thickness and keratinized mucosa width (KMW) were made at the time of implant placement (T0), crown placement (T1), and after 3 (T2) and 6 months (T3) of prosthetic loading. At each of these points, a radiographic evaluation of bone remodeling and marginal bone loss was also performed.

RESULTS

STH was significantly greater for implants placed >1 mm subcrestally than for those placed 1 mm subcrestally. After 12 months of follow-up, a very significant (p < 0.001) loss of KMW was observed, in addition to a marginal bone loss of 0.08 ± 0.1, 0.15 ± 0.2, and 0.14 ± 0.2 mm in the groups placed equicrestally, 1 mm subcrestally and >1 mm subcrestally, respectively. After the multiple linear regression, marginal bone loss was found to depend primarily on KMW (β = -0.43), while also being affected by STH (β = 0.32) and implant diameter (β = -0.28).

CONCLUSIONS

Marginal bone loss may be influenced by the position with respect to the bone crest, as well as the KMW, STH, and implant diameter. However, more well-controlled studies are needed to verify these above-mentioned findings with different implant designs and connections.

Three-dimensional representation of the Vita Toothguide 3D-Master: An in vivo clinical study

STATEMENT OF PROBLEM

The Vita Toothguide 3D-Master (Vita Zahnfabrik) is considered the dental shade guide in which the three dimensions of color - lightness, hue, and chroma - are most well-ordered in the CIELAB color space. No research has yet explored how well the Vita Toothguide 3D-Master is ordered in the 3D color space by recording color coordinates in vivo.

PURPOSE

To evaluate the spatial color distribution of the Vita Toothguide 3D-Master's lightness, chroma, and hue groups and its 26 physical shade tabs.

MATERIALS AND METHODS

The dental color (L*, C*, h°, a*, and b* color coordinates) of a healthy maxillary central incisor was recorded for 1361 participants (aged between 18 and 89 years) using a Vita Easyshade Compact spectrophotometer (Vita Zahnfabrik). The R 2.7.2. statistics program was used to create the visual representations.

RESULTS

The five lightness levels are those that are best distributed in the color space, in relation to the L* coordinates, followed by the chroma group and, finally, the hue group. The 5M1, 5M2, and 5M3 physical shade tabs are situated at a greater distance apart from the other tabs in the color space.

CONCLUSIONS

The Vita Toothguide 3D-Master's 26 physical shade tabs are satisfactorily distributed in three-dimensional space, although strict mathematical criteria are not followed. The natural dental shades that fall lower on the lightness scale are the most poorly represented by the physical shade tabs.

CLINICAL IMPLICATIONS

Darker teeth are poorly represented by the Vita Toothguide 3D-Master's physical shade tabs. The spatial distribution of dental shade guides needs to be improved to ensure they provide homogeneous coverage of the entire chromatic spectrum corresponding to natural teeth. This would help reduce the errors inherent to the subjective visual color selection process.

Explaining the colour of natural healthy gingiva

To examine the differences between natural gingival colour in men and women. To determine the degree of predictability of changes in the gingival colour coordinates recorded for healthy gingiva, according to age, long-term medication, frequency of toothbrushing, and smoking habits. The CIELAB colour coordinates were recorded using a spectrophotometer for 360 Caucasian adult participants (aged 18-92 years), in three zones of the healthy attached gingiva of the maxillary central incisor. Regression models were created for each zone and each sex, taking the L*, a* and b* coordinates as dependent variables and age, frequency of toothbrushing, smoking habits (0-non-smoker; 1-smoker) and whether participants were taking long-term medication (0-no; 1-yes) as independent variables. The statistical analysis was conducted with SPSS version 26.0, using multiple regression models. Statistically significant differences between men and women were found only for colour coordinate b*, in all three zones. The only colour coordinate on which the predictor variables had a significant effect was the L* coordinate. In men, age and long-term medication had the greatest effect as predictors (maximum R2 = 0.149). In women, frequency of toothbrushing was the strongest predictor in the predictive models (maximum R2 = 0.099). The colour of gingiva in men contained a larger amount of blue, given that significantly lower values for colour coordinate b* were recorded in men than women, although this difference lacked clinical implications. For both sexes, the regression models produced had a modest predictive capacity. The L* coordinate was the dependent variable that showed the greatest predictability.

Comparison of surface roughness of additively manufactured implant-supported interim crowns fabricated with different print orientations

PURPOSE

To assess the influence of print orientation on the surface roughness of implant-supported interim crowns manufactured by using digital light processing (DLP) 3D printing procedures.

MATERIALS AND METHODS

An implant-supported maxillary right premolar full-contour crown was obtained. The interim restoration design was used to fabricate 30 specimens with 3 print orientations (0, 45, and 90 degrees) using an interim resin material (GC Temp PRINT) and a DLP printer (Asiga MAX UV) (n = 10). The specimens were manufactured, and each was cemented to an implant abutment with autopolymerizing composite resin cement (Multilink Hybrid Abutment). Surface roughness was assessed on the buccal surface of the premolar specimen by using an optical measurement system (InfiniteFocusG5 plus). The data were analyzed with a Shapiro-Wilk test, resulting in a normal distribution. One-way ANOVA and the Tukey HSD tests were selected (α = 0.05).

RESULTS

Statistically significant discrepancies were found in the surface roughness mean values among the groups tested (p < 0.001). The lowest mean ± standard deviation surface roughness was found with the 90-degree group (1.2 ± 0.36 μm), followed by the 0-degree orientation (2.23 ± 0.18 μm) and the 45-degree group (3.18 ± 0.31 μm).

CONCLUSIONS

Print orientation parameter significantly impacted the surface roughness of the implant-supported interim crowns manufactured by using the additive procedures tested.

Influence of implant angulation and clinical implant scan body height on the accuracy of complete arch intraoral digital scans

STATEMENT OF PROBLEM

The accuracy of digital implant scans can be affected by the implant angulation, implant depth, or interimplant distance. However, studies analyzing intraoral scanning accuracy with different implant angulations and different scan body heights are scarce.

PURPOSE

The purpose of this in vitro study was to determine the influence of the implant angulation and clinical implant scan body height on the accuracy of complete arch scans.

MATERIAL AND METHODS

Two definitive implant casts with 6 implant analogs (Zimmer Biomet) were obtained: 1 cast had all the implant analogs parallel (GP group), and 1 cast had the implant analogs with divergence of up to 30 degrees (GD group). A coordinate measurement machine (Global Evo 09.15.08) was used to measure the positions of the implant analogs. Each group was divided into 3 subgroups depending on the clinical implant scan body height: 10, 6, and 3 mm. An implant scan body (Elos Accurate Scan Body Brånemark system) was positioned on each implant analog. A total of 10 scans of each subgroup were recorded by using an intraoral scanner (TRIOS 3). Each STL file obtained was imported into a reverse engineering software program (Geomagic), and linear and angular Euclidean measurements were obtained. The Euclidean calculations between the implant analog positions of the definitive implant casts were used as a reference to calculate the discrepancies among the corresponding subgroups. The Kolmogorov-Smirnov test revealed that the lineal measurements were not normally distributed, so the Kruskal-Wallis and pairwise comparison Dunn tests were used (α=.05). The Kolmogorov-Smirnov test revealed that the angular measurements were normally distributed. Therefore, the 2-way ANOVA and pairwise comparison Tukey tests were used (α=.05).

RESULTS

The Kruskal-Wallis test revealed significant differences in the linear Euclidean medians between the GP and GD groups with different clinical implant scan body heights (H(5)=23.18, P<.001). Significant differences in the linear Euclidean medians were computed between the GP-6 and GD-10 subgroups (P=.009), GD-3 and GD-6 subgroups (P=.029), and GD-3 and GD-10 subgroups (P=.001). Two-way ANOVA revealed that the implant angulation (F(1, 3.3437)=28.93, P<.001) and clinical implant scan body height (F(2, 0.4358)=3.77, P=.029) were significant predictors of discrepancies in the angular measurement.

CONCLUSIONS

Implant angulation and clinical scan body height influenced scanning accuracy. The lowest clinical implant scan body height tested had the lowest accuracy in both parallel and angled implants, but statistically significant differences were found only in the angled group.

Insight into (Electro)magnetic Interactions within Facet-Engineered BaFe12O19/TiO2 Magnetic Photocatalysts

A series of facet-engineered TiO2/BaFe12O19 composites were synthesized through hydrothermal growth of both phases and subsequent deposition of the different, faceted TiO2 nanoparticles onto BaFe12O19 microplates. The well-defined geometry of the composite and uniaxial magnetic anisotropy of the ferrite allowed alternate interfaces between both phases and fixed the orientation between the TiO2 crystal structure and the remanent magnetic field within BaFe12O19. The morphology and crystal structure of the composites were confirmed by a combination of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses together with the detailed study of BaFe12O19 electronic and magnetic properties. The photocatalytic activity and magnetic field effect were studied in the reaction of phenol degradation for TiO2/BaFe12O19 and composites of BaFe12O19 covered with a SiO2 protective layer and TiO2. The observed differences in phenol degradation are associated with electron transfer and the contribution of the magnetic field. All obtained magnetic composite materials can be easily separated in an external magnetic field, with efficiencies exceeding 95%, and recycled without significant loss of photocatalytic activity. The highest activity was observed for the composite of BaFe12O19 with TiO2 exposing {1 0 1} facets. However, to prevent electron transfer within the composite structure, this photocatalyst material was additionally coated with a protective SiO2 layer. Furthermore, TiO2 exposing {1 0 0} facets exhibited significant synergy with the BaFe12O19 magnetic field, leading to 2 times higher photocatalytic activity when ferrite was magnetized before the process. The photoluminescence emission study suggests that for this particular combination, the built-in magnetic field of the ferrite suppressed the recombination of the photogenerated charge carriers. Ultimately, possible effects of complex electro/magnetic interactions within the magnetic photocatalyst are shown and discussed for the first time, including the anisotropic properties of both phases.

Comparison of the Surface Roughness of CAD/CAM Metal-Free Materials Used for Complete-Arch Implant-Supported Prostheses: An In Vitro Study

The roughness of the intra-oral surfaces significantly influences the initial adhesion and the retention of microorganisms. The aim of this study was to analyze the surface texture of four different CAD-CAM materials (two high-performance polymers and two fifth-generation zirconia) used for complete-arch implant-supported prostheses (CAISPs), and to investigate the effect of artificial aging on their roughness. A total of 40 milled prostheses were divided into 4 groups (n = 10) according to their framework material, bio.HPP (B), bio.HPP Plus (BP), zirconia Luxor Z Frame (ZF), and Luxor Z True Nature (ZM). The areal surface roughness "Sa" and the maximum height "Sz" of each specimen was measured on the same site after laboratory fabrication (lab as-received specimen) and after thermocycling (5-55 °C, 10,000 cycles) by using a noncontact optical profilometer. Data were analyzed using SPSS version 28.0.1. One-way ANOVA with multiple comparison tests (p = 0.05) and repeated measures ANOVA were used. After thermocycling, all materials maintained "Sa" values at the laboratory as-received specimen level (p = 0.24). "Sz" increased only for the zirconia groups (p = 0.01). B-BP exhibited results equal/slightly better than ZM-ZF. This study provides more realistic surface texture values of new metal-free materials used in real anatomical CAISPs after the manufacturing and aging processes and establishes a detailed and reproducible measurement workflow.

Fifteen ceramic gingival samples: A proposed gingival shade guide

OBJECTIVE

(1) To put forward a set of valid pink ceramic samples for subjective gingival colour selection in the Caucasian population, and (2) to assess the quality of the shade matches provided by the selected pink samples.

METHODS

The ceramic gingival shade samples (n = 133) were obtained by mixing pairs of basic colours from a single system. In each mixture, the proportions of the colours were altered in 10% increments, following the numerical order used by the manufacturers of the three colour systems under study (Heraceram, Vita VM9 and IPS Style). The CIELAB colour coordinates were recorded using spectrophotometry in three zones of healthy anterior gingiva (n = 360). The sample was randomly divided into two subsamples, each of which contained 180 participants. Subsample 1 was used to select the ceramic gingival samples that provided the best shade matches, using the k-means clustering method. Subsample 2 was used to assess the chromatic validity of the selected gingival samples, according to the coverage error.

RESULTS

To identify the ceramic gingival samples that best represented participants' gingival colour, the minimum colour differences (ΔEab∗, ΔE00) between the cluster centroids and the 133 gingival samples were calculated. Fifteen gingival samples were selected: 8 from the Heraceram system, 4 from the VM9 system, and 3 from the IPS Style system. Coverage errors for the 15 gingival samples fell below the gingival clinical acceptability thresholds in the three gingival zones examined.

CONCLUSIONS

The 15 ceramic gingival colour samples provide satisfactory coverage of the gingival colour space, with coverage errors below the ΔE00 clinical acceptability threshold of 2.9 units. These pink colour samples have the potential to provide good gingival shade matches in subjective colour selection.

CLINICAL SIGNIFICANCE

Mixing basic ceramic colours is a viable method for generating a series of pink shades that can be used as a physical gingival shade guide. The resulting guide provides valid results (under the acceptability thresholds) for subjective selection gingival colour selection in clinical practice.

Degree of Standardisation in Ceramic Gingival Systems

No gingival shade guide exists that can be used as a 'gold standard' in gingival shade selection. This research, therefore, aimed to determine whether comparable results in subjective gingival shade selection can be achieved using basic gingival colours produced by distinct manufacturers. It also aimed to explore how coverage of the colour space is affected by mixing these basic colours to create additional shades. To achieve these objectives, the basic gingival colours of three ceramic systems (Heraceram, Kulzer, Madrid, Spain; Vita VM9, Vita Zahnfabrik, Bad Säckingen, Germany; IPS Style, Ivoclar, Schaan, Liechtenstein) were analysed. The colour systems were expanded by creating porcelain gingival samples, whose colours were obtained by mixing the basic colours, altering each mixture by increments of 10%, and respecting the numerical order used by manufacturers to identify the colours. The colour coordinates of the basic and additional colours were recorded using spectrophotometry, and the intra- and inter-system colour differences were calculated using the Euclidean (ΔEab) and CIEDE2000 (ΔE00) formulae. None of the basic colours in the three systems, despite their similar nomenclature, were found to be interchangeable (the colour differences exceeded the gingival acceptability threshold: ΔE00 2.9 units). The expanded gingival colour systems, with mixtures altered by 10% increments, notably increased the gingival colour space covered by the original systems. The authors concluded that there are clear differences between the basic gingival colours produced by distinct manufacturers using the same nomenclature. Ceramic samples produced by mixing basic gingival colours are a resource with the potential to improve subjective gingival shade matching.

Coverage error and shade-match accuracy in three ceramic gingival systems

STATEMENT OF PROBLEM

Research into the coverage error (CE) of gingival systems that have been expanded by using ceramic specimens created by mixing basic colors is lacking.

PURPOSE

The purpose of this in vitro study was to compare the CEs of 3 ceramic gingival color systems that have been expanded with basic-color mixtures from a sample of 360 White participants and to classify the participants according to the accuracy of the shade match achieved with each system.

MATERIAL AND METHODS

L*a*b* color coordinates were recorded in 3 zones of attached gingiva for 360 White participants with healthy gingival tissue (187 men and 173 women). The CEs were calculated for 3 ceramic gingival systems that had been expanded with specimens obtained by mixing the basic colors in consecutive order, the color percentages in each mixture having been altered by 10% increments. The systems were Heraceram (Kulzer GmbH) (n=51); Vita VM9 (Vita-Zahnfabrik) (n=41); and IPS Style (Ivoclar AG) (n=41). The participants were classified into 3 groups according to how well the selected shade matched their gingival color (excellent, acceptable, or poor). The data were analyzed using a 1-way ANOVA with a randomized block design and the homogeneity of proportions test (α=.05).

RESULTS

Statistically significant differences were found between the CEs of the 3 expanded gingival systems in the 3 zones where gingival color was measured (P<.001). The expanded Heraceram system had the smallest CE (ΔE00: minimum 2.66 in the middle zone and maximum 2.95 at the mucogingival line). In the 3 gingival zones, the expanded IPS Style system produced the largest percentage of participants with a poor shade match (ΔE00: minimum 71.4% at the mucogingival line and maximum 75.8% at the free gingival margin), while the expanded Heraceram system had the lowest percentage of participants with a poor shade match (ΔE00: minimum 33.3% in the middle zone and maximum 41.7% at the mucogingival line).

CONCLUSIONS

The CEs calculated for the expanded Vita VM9 and IPS Style ceramic gingival color systems exceeded the clinical acceptability thresholds in the 3 zones examined. According to the ΔE00 formula, the gingival color of at least 33% of participants matched poorly with the expanded systems studied.

Influence of the Use of Transepithelial Abutments vs. Titanium Base Abutments on Microgap Formation at the Dental Implant-Abutment Interface: An In Vitro Study

This in vitro study aimed to assess the presence of microgaps at the implant-abutment interface in monolithic zirconia partial implant-supported fixed prostheses on transepithelial abutments versus Ti-base abutments.

METHODS

Sixty conical connection dental implants were divided into two groups (n = 30). The control group consisted of three-unit bridge monolithic zirconia connected to two implants by a transepithelial abutment. The test group consisted of monolithic zirconia three-unit restoration connected to two implants directly by a titanium base (Ti-base) abutment. The sample was subjected to thermocycling (10,000 cycles at 5 °C to 55 °C, dwelling time 50 s) and chewing simulation (300,000 cycles, under 200 N at frequencies of 2 Hz, at a 30° angle). The microgap was evaluated at six points (mesiobuccal, buccal, distobuccal, mesiolingual, lingual, and distolingual) of each implant-abutment interface by using a scanning electron microscope (SEM). The data were analyzed using the Mann-Whitney U tests (p > 0.05).

RESULTS

The SEM analysis showed a smaller microgap at the implant-abutment interface in the control group (0.270 μm) than in the test group (3.902 μm). Statistically significant differences were observed between both groups (p < 0.05).

CONCLUSIONS

The use or not of transepithelial abutments affects the microgap size. The transepithelial abutments group presented lower microgap values at the interface with the implant than the Ti-base group in monolithic zirconia partial implant-supported fixed prostheses. However, both groups had microgap values within the clinically acceptable range.

Study of attached gingiva space color according to gender and age in Caucasian population

OBJECTIVE

To describe the color of the healthy attached gingiva adjacent to the maxillary incisors and to evaluate the effect of age and gender on CIELAB color coordinates.

MATERIALS AND METHODS

The study included 216 Caucasian individuals (129 females and 87 males) divided into three age groups. A SpectroShade Micro spectrophotometer was used to register color coordinates at 2.5 mm apical of the zenith of the upper central incisors. Descriptive and inferential statistical analysis was performed.

RESULTS

The minimum and maximum coordinates in which the CIELAB natural gingival space is delimited are: L* minimum 40.4 - L* maximum 61.2; a* minimum 17.0 - a* maximum 30.2; b* minimum 9.8 - and b* maximum 21.9. There are statistically significant differences between males and females for coordinates L*, a* and b* in the attached gingival area selected. Age had a significant effect on coordinate b* (p = 0.000).

CONCLUSIONS

Statistically significant differences were found between the L*, a* and b* color coordinates of the attached gingiva between men and women, although the color difference is below the clinical acceptance threshold. The attached gingiva takes on a bluish color as the patients get older, which means that the b* coordinate decreases.

CLINICAL SIGNIFICANCE

With a prosthodontic approach, knowledge of the CIELAB natural attached gingival coordinates based on the patient's age and gender will facilitate the clinician's work in selecting the appropriate color. The CIELAB system values found can be used as a gingival shade guide reference.

Magnetic carbon Fe3O4 nanocomposites synthesized via Magnetic Induction Heating

Magnetic Induction Heating (MIH) of magnetite nanoparticles is employed as a novel synthesis procedure of carbon based magnetic nanocomposites. Magnetic nanoparticles (Fe₃O₄) and fructose (1:2 weight ratio) were mechanically mixed and submitted to a RF magnetic field (305 kHz). The heat generated by the nanoparticles leads to the decomposition of the sugar and to the formation of an amorphous carbon matrix. Two sets of nanoparticles, with mean diameter sizes of 20 and 100 nm, are comparatively analysed. Structural (X-ray diffraction, Raman spectroscopy, Transmission Electron Microscopy (TEM)), electrical and magnetic (resistivity, SQUID magnetometry) characterizations confirm the nanoparticle carbon coating through the MIH procedure. The percentage of the carbonaceous fraction is suitably increased controlling the magnetic heating capacity of the magnetic nanoparticles. The procedure enables the synthesis of multifunctional nanocomposites with optimized properties to be applied in different technological fields. Particularly, Cr (VI) removal from aqueous media is presented employing the carbon nanocomposite with 20 nm Fe₃O₄ nanoparticles.

Fe3O4-SiO2 Mesoporous Core/Shell Nanoparticles for Magnetic Field-Induced Ibuprofen-Controlled Release

Hybrid magnetic nanoparticles made up of an iron oxide, Fe₃O₄, core and a mesoporous SiO₂ shell with high magnetization and a large surface area were proposed as an efficient drug delivery platform. The core/shell structure was synthesized by two seed-mediated growth steps combining solvothermal and sol-gel approaches and using organic molecules as a porous scaffolding template. The system presents a mean particle diameter of 30(5) nm (9 nm magnetic core diameter and 10 nm silica shell thickness) with superparamagnetic behavior, saturation magnetization of 32 emu/g, and a significant AC magnetic-field-induced heating response (SAR = 63 W/g_Fe3O4, measured at an amplitude of 400 Oe and a frequency of 307 kHz). Using ibuprofen as a model drug, the specific surface area (231 m²/g) of the porous structure exhibits a high molecule loading capacity (10 wt %), and controlled drug release efficiency (67%) can be achieved using the external AC magnetic field for short time periods (5 min), showing faster and higher drug desorption compared to that of similar stimulus-responsive iron oxide-based nanocarriers. In addition, it is demonstrated that the magnetic field-induced drug release shows higher efficiency compared to that of the sustained release at fixed temperatures (47 and 53% for 37 and 42 °C, respectively), considering that the maximum temperature reached during the exposure to the magnetic field is well below (31 °C). Therefore, it can be hypothesized that short periods of exposure to the oscillating field induce much greater heating within the nanoparticles than in the external solution.

Double Lateral Sliding Bridge Flap versus Laterally Closed Tunnel for the Treatment of Single Recessions in the Mandibular Anterior Teeth: A Pseudorandomized Clinical Trial

(1) Background: This study compared the clinical and esthetic results of the double lateral sliding bridge flap (DLSBF) and the laterally closed tunnel (LCT) techniques, with a subepithelial connective tissue graft (SCTG), for the treatment of single Miller class II-III recessions in the mandibular anterior teeth. (2) Methods: This pseudorandomized clinical trial evaluated 14 patients, 7 of whom were part of the DLSBF + SCTG group, with an average follow-up of 58.7 ± 24.0 months, and 7 of whom were in the LCT + SCTG group, with an average follow-up of 16.7 ± 3.3 months. Clinical and esthetic evaluations of the following parameters were performed and the results for the two groups were compared: gingival recession depth, probing depth, keratinized tissue width, gingival thickness, percentage of root coverage and root coverage esthetic score. (3) Results: After the follow-up period, each technique provided evidence of a reduction in recession depth and clinical attachment level, as well as increased keratinized tissue width and gingival thickness, with statistically significant differences (p < 0.05). The analysis showed that gingival recession depth decreased less in the DLSBF group (4.3 ± 1.2 mm to 0.6 ± 1.1 mm) than it did in the LCT group (4.9 ± 1.1 mm to 0.1 ± 0.4 mm), but no significant difference was found between the two groups. Similarly, a greater reduction in the clinical attachment level parameter was observed in the LCT group, while a greater increase in gingival thickness was observed in the DLSBF group. The presence of scars was the only parameter for which statistically significant differences (p < 0.05) between the two study groups were found. (4) Conclusions: Within the limitations of the study, it indicates that the LCT + SCTG technique may be considered an optimal technique in terms of reducing gingival recession depth, complete root coverage and esthetic results for the treatment of single gingival recessions in the mandibular anterior teeth.

Epidemiological Study on Burnout in Spanish Dentists: Underlying Psychological Factors

The aim of this work is to study the personality factors and coping styles of Spanish dentists when facing burnout syndrome, through epidemiological work. An epidemiological study of 1928 Spanish dentists was undertaken through an online survey, which registered the age and gender, and three questionnaires: NEO-FFI (personality traits), Brief COPE (coping styles), and MBI-HSS (burnout questionnaire). A multivariate analysis and an explanatory binary logistic regression model were used to estimate the presence of burnout. Neuroticism turned out to be the strongest indicator (OR 1.10; IC 95% 1.09–1.14), while extraversion (OR 0.93; IC 95% 0.91–0.95) and agreeableness (OR 0.94; IC95% 0.92–0.98) showed an inverse relationship with the occurrence of burnout, as did age (OR 0.9; IC95% 0.96–0.99). Conscientiousness (OR 1.0; IC95% 1.00–1.06) had a direct relationship with the presence of burnout. An avoidant coping style was the only indicative coping style (OR 1.04 IC95% 1.02–1.06). Approximately 70% of the dentists scored high on one of the three dimensions of burnout. No differences were found in the degree of burnout according to gender. Certain personality factors (neuroticism, extraversion, agreeableness, and conscientiousness), the avoidant coping style, and age are powerful indicators to attempt to forecast the presence of burnout syndrome in dentists.

Intraoral Digital Scans for Fabricating Tooth-Supported Prostheses Using a Custom Intraoral Scan Body

This article describes a technique to assist with intraoral digital scans for fabricating tooth-supported prostheses by using a custom intraoral scan body when the extension of the scan or the clinical characteristics might compromise the reliability of the intraoral digital scan. A preliminary intraoral scan of the tooth preparations is used to design a custom intraoral scan body which is manufactured using polymethylmethacrylate and a 5-axis milling machine. A low-viscosity polyvinyl siloxane impression of the tooth preparations is obtained using the custom intraoral scan body. Subsequently, the custom intraoral scan body is digitized using an intraoral scanner. A design software program is used to align the digitized custom intraoral scan body with the preliminary intraoral scan to obtain the definitive virtual cast. This technique aims to reduce manual conventional laboratory procedures such as pouring dental impression or die trimming which might minimize inaccuracies on the virtual definitive cast.

Techniques to improve the accuracy of complete-arch implant intraoral digital scans: A systematic review

STATEMENT OF PROBLEM

The best method of optimizing the accuracy of complete-arch intraoral digital scans is still unclear. For instance, the location of the scan bodies can be significantly distorted with respect to their actual positions, which would lead to a nonpassive fit of the definitive prosthesis.

PURPOSE

The purpose of this systematic review was to analyze available techniques for improving the accuracy of digital scans in implant-supported complete-arch fixed prostheses.

MATERIAL AND METHODS

Three databases (Medline, Embase, and Google Scholar) were searched, and the results obtained were supplemented by a hand search. Specific descriptors identified techniques whose objective were to increase the accuracy of digital scans in implant-supported complete-arch fixed prostheses. Titles and abstracts were screened by 2 independent reviewers, and unclear results were discussed with a third independent reviewer. A qualitative analysis based on procedural parameters was used. The interexaminer agreements of both were assessed by the Cohen kappa statistic, and the Risk of Bias Tool was used to assess the risk of bias across the studies.

RESULTS

A total of 17 techniques matching the inclusion criteria were evaluated. Higher accuracy but also differences regarding the need for supplementary devices, number of intraoral scans, and time consumption of clinical and software program steps were observed compared with the conventional digital scanning protocol. The use of a splinting device was common to most of the studies. The outcome variables for the evaluation of the effectiveness of these protocols were heterogeneous.

CONCLUSIONS

The use of additional techniques during intraoral scanning can improve accuracy in implant-supported complete-arch fixed prostheses. However, higher complexity for those procedures should be expected.

Behaviour and Anxiety Management of Paediatric Dental Patients through Virtual Reality: A Randomised Clinical Trial

Clinicians should appreciate the effectiveness of virtual reality (VR) headsets for managing both the anxiety and the behaviour of non-cooperative paediatric patients who require treatment over several dental appointments. The aim of this study was to assess the effectiveness of using a VR headset as a distraction for managing the anxiety and behaviour of paediatric patients during their dental treatment. Eighty patients, aged between five and ten years old and who required dental treatment over three or more appointments, were randomly allocated into two groups. One group used a VR headset during all their appointments, and the other one did not use any distraction technique. The patients were asked to take a Facial Image Scale Test during their first and last appointments to assess their level of anxiety. Additionally, the dentist completed the Frankl Test to quantify the child's behaviour at the beginning and the end of their treatment. The results obtained, both from the group using the VR headset and from the control group, were compared using the chi-square test. The use of a VR headset during dental treatment significantly reduced anxiety (95% of the children were happy) and improved behaviour (100% positive behaviour) as compared with the control group (40% and 57.5%, respectively). A VR headset can effectively distract a paediatric patient, helping to reduce anxiety and manage behaviour during dental treatment.

Main 3D Manufacturing Techniques for Customized Bone Substitutes. A Systematic Review

Clinicians should be aware of the main methods and materials to face the challenge of bone shortage by manufacturing customized grafts, in order to repair defects. This study aims to carry out a bibliographic review of the existing methods to manufacture customized bone scaffolds through 3D technology and to identify their current situation based on the published papers. A literature search was carried out using "3D scaffold", "bone regeneration", "robocasting" and "3D printing" as descriptors. This search strategy was performed on PubMed (MEDLINE), Scopus and Cochrane Library, but also by hand search in relevant journals and throughout the selected papers. All the papers focusing on techniques for manufacturing customized bone scaffolds were reviewed. The 62 articles identified described 14 techniques (4 subtraction + 10 addition techniques). Scaffold fabrication techniques can be also be classified according to the time at which they are developed, into Conventional techniques and Solid Freeform Fabrication techniques. The conventional techniques are unable to control the architecture of the pore and the pore interconnection. However, current Solid Freeform Fabrication techniques allow individualizing and generating complex geometries of porosity. To conclude, currently SLA (Stereolithography), Robocasting and FDM (Fused deposition modeling) are promising options in customized bone regeneration.

Dental student, dentist, dental assistant, and layperson perception of pink gingival porcelain color

STATEMENT OF PROBLEM

How pink gingival porcelain color is perceived by participants classified according to profession and sex is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the degree of correlation between the ordering of color tabs by participants classified according to profession, years of dental work experience, and sex and the ideal chromatic order based on the color coordinate L∗ (lightness).

MATERIAL AND METHODS

Twenty-one colored specimens made of Heraceram pink gingival porcelain were used. A group of 352 participants (118 men and 234 women) comprised of dental students (n=126), dentists (n=54), dental assistants (n=56), and laypersons (n=116) were enrolled. They were asked to order the specimens starting from the lightest to the darkest. The Kendall coefficients of concordance W and correlation T were used to determine whether the individuals in each experimental group rating the specimens were consistent and accurate.

RESULTS

The degree of agreement between the ideal ordering and that carried out by the participants within the different professional categories was greater than 0.8 in all assessments. No statistically significant differences were found among the groups in relation to professional category, work experience, or sex (P>.05). The Kendall coefficients were higher in the ranking of the darker specimens for all groups of participants.

CONCLUSIONS

No statistically significant differences were found among dentists, dental assistants, dental students, and laypersons in the arrangement of pink porcelain specimens according to their lightness. In addition, in all groups, the darker gingival specimens were ordered significantly better according to their lightness than the lighter specimens.

Giant Stress Impedance Magnetoelastic Sensors Employing Soft Magnetic Amorphous Ribbons

Soft magnetic amorphous alloys obtained via rapid quenching techniques are widely employed in different technological fields such as magnetic field detection, bio labeling, non-contact positioning, etc. Among them, magnetoelastic applications stand out due to excellent mechanical properties exhibited by these alloys, resulting from their amorphous structure, namely, their high Young modulus and high tensile strength. In particular, the giant stress impedance (GSI) effect represents a powerful tool to develop highly sensitive magnetoelastic sensors. This effect is based on the changes in the high-frequency electric impedance as the result of the variation in magnetic permeability of the sample under the action of mechanical stresses. In this work, the GSI effect is analyzed in two soft magnetic ribbons ((Co_0.93 Fe_0.07)₇₅ Si_12.5 B_12.5 and (Co_0.95 Fe_0.05)₇₅ Si_12.5 B_12.5) for the subsequent development of two practical devices: (i) the characterization of the variations in the cross-section dimensions of irregularly shaped elements, and (ii) the design of a flow meter for measuring the rate of flow of water through a pipe.

Interim restoration using dynamic abutments to re-treat a single-implant crown with a labial angulation: A clinical report

The cause of some peri-implant problems may be primarily attributable to the design of the prosthesis. A screw-retained interim implant may be advisable for reversibility and to avoid peri-implant cement, although screw retention may be difficult for maxillary anterior implants with a labial angulation. In the treatment described, a interim screw-retained crown was attached to a dynamic abutment with a lingual screw access hole to obtain a correctly fitting restoration.

Dental Students' Perceived Clinical Competence in Prosthodontics: Comparison of Traditional and Problem-Based Learning Methodologies

The aim of this study was to compare the perceived competence for treating prosthodontic patients of two samples of fourth-year dental students: those educated using traditional methodologies and those educated using problem-based learning (PBL). Two cohorts of fourth-year dental students at a dental school in Spain were surveyed: the traditional methods cohort (n=46) was comprised of all students in academic years 2012 and 2013, and the PBL cohort (n=57) was comprised of all students in academic years 2014 and 2015. Students in both cohorts reported the number of prosthodontic treatments they carried out per year and their perceived level of competence in performing such treatments. The results showed that the average number of treatments performed was similar for the two cohorts, except the number of metal-based removable partial dentures was significantly higher for students in the traditional (0.8±1.0) than the PBL (0.4±0.6) cohort. The level of perceived competence to treat complete denture patients for the combined cohorts was significantly higher (7.3±1.1) than that for partial acrylic dentures (6.7±1.5) and combined dentures (5.7±1.3). Students' clinical competence in prosthodontics mainly depended on number of treatments performed as the operator as well as the assistant. Students in the traditional methods cohort considered themselves to be significantly more competent at treating patients for removable partial and fixed prostheses (7.8±1.1 and 7.6±1.1, respectively) than did students in the PBL cohort (6.4±1.5 and 6.6±1.5, respectively). Overall, however, the study found that practical experiences were more important than the teaching method used to achieve students' perceived competence.

Comparison of the CIELab and CIEDE 2000 Color Difference Formulas on Gingival Color Space

PURPOSE

To evaluate the CIELAB and CIEDE2000 formulas to determine which better reflects the difference in color perception, and whether there are gender differences in color perception.

MATERIALS AND METHODS

Fifty-six participants grouped 21 different-colored disks made of pink porcelain (color range: from 36.8 to 63.9 for L^* , from 16.4 to 35.2 for a^* , from 6.2 to 21.6 for b^* ), in which the only requirement was that each group be comprised of disks with chromatically indistinguishable colors. Each participant was free to choose the number and composition of the groups. Using the results obtained, a dissimilarity matrix was generated, and nonmetric multidimensional scaling (MDS) was applied to obtain the coordinates of the disks within a Euclidean space.

RESULTS

The linear correlation coefficient between the interpoint distances of the MDS configuration (MDS_total sample) and the color differences with the CIELAB formula (ΔE^* _ab ) was 0.719 (p < 0.001), whereas with the CIEDE2000 formula (ΔE00), it was 0.726 (p < 0.001). For the configuration obtained in the women's group (MDS_w), the correlations between the interpoint distances and the CIELab color difference was 0.720 (p < 0.001), and the CIEDE2000 color differences was 0.730 (p < 0.001). For the configuration obtained in the men's group (MDS_m), the perceived color differences, calculated with both formulas, were less sensitive, 0.670 for CIELab formula and 0.677 for CIEDE2000 formula.

CONCLUSIONS

Considering the limitations of this study, the data analyzed indicated that the CIEDE2000 formula reflected the color differences perceived by the human eye similar to the CIELAB formula (ΔE^* _ab ). Also, women were confirmed to be more sensitive than men to differences in color.

Factors Affecting the Decision to Use Cemented or Screw-Retained Fixed Implant-Supported Prostheses: A Critical Review

PURPOSE

This review aimed to compile and enumerate all the factors described in the literature that may affect the decision to use either cemented or screw-retained restorations and to determine the relative weights of each factor by type of retention and prosthesis.

MATERIALS AND METHODS

The literature was reviewed, and the factors were classified as either determining (present in a clinical situation in which one of the retention mechanisms was clearly more suitable than the other) or conditioning (present in clinical situations in which one type of restoration was not clearly more advantageous than the other).

RESULTS

Three determining factors (esthetic outcome, retention, and biologic risk) and five conditioning factors (passive fit, fracture strength, occlusal area, complications, and retrievability) were identified.

CONCLUSION

Although there is not a clearly better alternative for all clinical situations, determining factors in certain scenarios can render one of the two approaches more recommendable. For esthetic reasons, when the implant angle cannot be corrected to conceal the access hole, cementation is more suitable; however, screw retention is the better option when the occlusal space is under 6 mm or margins cannot be located supra- or equigingivally. In the absence of determining factors, the decision should be based on conditioning factors, which carry different weights depending on the type of prosthesis.

Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation

Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic transformation (martensite to austenite). In some of these alloys, the austenite phase can be retained on cooling under high magnetic fields, being the retained phase metastable after field removing. Here, we report a giant direct magnetocaloric effect linked to the anomalous forward martensitic transformation (austenite to martensite) that the retained austenite undergoes on heating. Under moderate fields of 10 kOe, an estimated adiabatic temperature change of 9 K has been obtained, which is (in absolute value) almost twice that obtained in the conventional transformation under higher applied fields. The observation of a different sign on the temperature change associated to the same austenite to martensite transformation depending on whether it occurs on heating (retained) or on cooling is attributed to the predominance of the magnetic or the vibrational entropy terms, respectively.

Association Between Sociodemographic Factors, Personality, and Oral Habits (Tooth Brushing and Smoking) in Spanish Adults

PURPOSE

The aim of the present study was to describe personality traits of a sample of Spanish adults, identify the main sociodemographic factors related to personality, and assess the influence of these traits on healthy dental habits.

MATERIALS AND METHODS

A cross-sectional design was used with 235 subjects, all of Spanish nationality and aged between 18 and 80 years, with a minimum educational level (ie, they had completed only the minimum obligatory schooling), ensuring that none of the subjects had any psychologic disturbance. The data on five personality dimensions were recorded. Sociodemographic and behavioral standard scores (z) were studied for each personality dimension, and the scores were related to the other variables studied.

RESULTS

A significant linear correlation was observed between the z scores of the personality factors and the sociodemographic and behavioral characteristics. The men had personalities with significantly less neuroticism, less openness, less agreeableness, and less conscientiousness than the women. In behavioral terms, those who brushed more than once a day were more agreeable (0.1 ± 0.9) than those who only brushed once a day (-0.2 ± 1.2), and smokers had higher mean scores for extroversion (0.3 ± 0.9) than did nonsmokers (-0.1 ± 1.0).

CONCLUSION

The most developed personality traits in this sample, as in the reference population, were conscientiousness (123.1 ± 22.9 points) and agreeableness (119.2 ± 19.1 points). The main sociodemographic factors of personality were found to be age and sex. Moreover, it was observed that certain personality dimensions were linked to smoking and tooth brushing habits.

Personality traits and dental anxiety in self-reported bruxism. A cross-sectional study

OBJECTIVES

The aim of this study was to investigate the association between psychological factors (Personality and Dental anxiety) with self-reported bruxism-related symptoms.

METHODS

526 subjects, over 18 years old and not seeking dental treatment, were recruited from the families and acquaintances of dental students from the University of Salamanca. Bruxism activity was estimated by means of a six-item questionnaire aimed at recording common bruxism-related symptoms and clenching/grinding awareness. The Spanish version of the modified dental anxiety scale (MDAS) was used to determine the level of anxiety perceived in 5 typical scenarios of dental assistance. The NEO-FFI inventory was applied to assess personality profiles associated with 5 different factors (neuroticism, extroversion, openness, agreeableness, and conscientiousness). Pearson correlations, Student T-tests, and logistic regression modelling were used for the statistical analyses.

RESULTS

Thirty-five point nine percent of this adults sample was classified as being bruxers, where sleep bruxers comprised more than half of the sample at 20.2%. Bruxers tended to perceive more anxiety in all of the situations included within the MDAS, where they exhibited a higher level of phobia towards the teeth scaling and local anaesthetic injection. The risk of being considered a bruxer is reduced with age (OR: 0.99), and increases proportionally for some personality traits, such as neuroticism (OR: 1.06) and extraversion(OR: 1.04), to the MDAS total score (OR: 1.08) and in smokers (OR: 1.61), after controlling for all potentially confounding factors.

CONCLUSIONS

Self-reported bruxism is significantly associated to several personality traits (mainly neuroticism and extraversion) and to the level of dental anxiety (MDAS score).

CLINICAL SIGNIFICANCE

Clinicians should be aware of the typical psychological profiles of patients who experience bruxism and the relationship with dental phobias.

Clinical Study of the 3D-Master Color System among the Spanish Population

PURPOSE

To study whether the shades of the 3D-Master System were grouped and represented in the chromatic space according to the three-color coordinates of value, chroma, and hue.

MATERIALS AND METHODS

Maxillary central incisor color was measured on tooth surfaces through the Easyshade Compact spectrophotometer using 1361 participants aged between 16 and 89. The natural (not bleached teeth) color of the middle thirds was registered in the 3D-Master System nomenclature and in the CIELCh system. Principal component analysis and cluster analysis were applied.

RESULTS

75 colors of the 3D-Master System were found. The statistical analysis revealed the existence of 5 cluster groups. The centroid, the average of the 75 samples, in relation to lightness (L*) was 74.64, 22.87 for chroma (C*), and 88.85 for hue (h*). All of the clusters, except cluster 3, showed significant statistical differences with the centroid for the three-color coordinates (p <0.001).

CONCLUSIONS

The results of this study indicated that 75 shades in the 3D-Master System were grouped into 5 clusters following coordinates L*, C*, and h* resulting from the dental spectrophotometer Vita Easyshade compact. The shades that composed each cluster did not belong to the same lightness color dimension groups. There was no special uniform chromatic distribution among the colors of the 3D-Master System.

Sociodemographic, Educational, Behavioral, and Psychologic Factors Underlying Orofacial Esthetics and Self-Reported Oral Health

PURPOSE

The aim of the present study was to compare sociodemographic, behavioral, and educational characteristics, together with personality traits, on perceptions of individuals' own oral health and orofacial esthetics.

MATERIALS AND METHODS

The participants had different educational backgrounds: dentistry students and students not following health care-related courses (university groups), and volunteers with no university studies (nonstudent group). The age range was 18 to 30 years. Sociodemographic and behavioral data and data on facial and dental attractiveness were gathered via personalized interviews. Personality traits were measured using the Big Five Inventory (BFI) (extroversion, agreeableness, conscientiousness, neuroticism, openness), and the Life Orientation Test was used to measure optimism and pessimism.

RESULTS

No statistically significant differences were observed among the three educational groups regarding the mean scores on the five personality variables. The nonstudent group accorded significantly greater importance to tooth color, whereas the university groups considered tooth alignment more important (P = .016). The logistic regression model used to predict perceptions about orofacial health and esthetics revealed that underlying behavioral (pattern of visits to dentist and brushing habits), psychologic (pessimism and agreeableness), and educational (training in dentistry) factors affected the participants' perceptions of orofacial attractiveness, oral satisfaction, and self-rated oral health.

CONCLUSIONS

The results of this study show that there are behavioral, psychologic, and educational factors that significantly modulate people's perceptions of orofacial esthetics, oral satisfaction, and self-rated oral health.

Does Length, Diameter, or Bone Quality Affect Primary and Secondary Stability in Self-Tapping Dental Implants?

PURPOSE

Implant stability is a clinically valuable measurement of the strength of implant anchorage in the bone during placement and in the post-osseointegration period. This study aimed to determine 1) the effect of implant diameter and length and bone quality on measurements of primary and secondary stability (insertion torque [IT] and implant stability quotient [ISQ]), 2) the correlation between IT and primary and secondary ISQ, and 3) differences in ISQ in the post-osseointegration period (secondary stability) compared with immediate post-placement (primary) stability.

PATIENTS AND METHODS

In this longitudinal clinical study, titanium self-tapping implants were inserted in edentulous patients. The implants were grouped according to 3 independent variables: length (10 and 11.5 mm), diameter (3.75 and 4.25 mm), and bone quality (Lekholm and Zarb classification) to analyze primary and secondary implant stability (outcome variables). Statistical analyses were performed using the Student t test for paired data, 1-way analysis of variance, and the Tukey procedure for multiple pairwise comparisons.

RESULTS

Data were collected on 88 self-tapping implants inserted in 63 partially edentulous patients. IT and implant stability were affected by diameter (3.75-mm implants, 26.5-N/cm IT and 74.0 ISQ; 4.25-mm implants, 33.8-N/cm IT and 77.0 ISQ) and bone type (type 1 + 2, 34.86-N/cm IT and 77.4 ISQ; type 3, 27.09-N/cm IT and 75.6 ISQ; type 4, 20.63-N/cm IT and 70.5 ISQ; P < .01 for all comparisons). Secondary ISQ was affected by diameter only (77.41 for 3.75- vs 75.51 for 4.25-mm implants). IT correlated with primary ISQ (R = 0.56; P < .01), although no clear correlation with secondary stability was found.

CONCLUSIONS

IT and primary ISQ in self-tapping implants differed in patients with different bone quality and implant diameter but did not differ between the 2 implant lengths compared in this study. Secondary stability was not substantially affected by any of these factors. Although IT was closely related to primary ISQ, it was unrelated to secondary ISQ. Very high primary ISQ values tended to decrease, whereas intermediate and low values tended to increase, in the transition to secondary stability.

Study of the most frequent natural tooth colors in the Spanish population using spectrophotometry

PURPOSE

To identify the most frequent natural tooth colors using the Easyshade Compact (Vita -Zahnfabrik) spectrophotometer on a sample of the Spanish population according to the 3D Master System.

MATERIALS AND METHODS

The middle third of the facial surface of natural maxillary central incisors was measured with an Easyshade Compact spectrophotometer (Vita Zahnfabrik) in 1361 Caucasian Spanish participants aged between 16 and 89 years. Natural tooth color was recorded using the 3D Master System nomenclature. The program used for the present descriptive statistical analysis of the results was SAS 9.1.3.

RESULTS

The results show that the most frequent dental color in the total sample studied is 3M1 (7.05%), followed by the intermediate shade 1M1.5 (6.91%) and 2L1.5 (6.02%).

CONCLUSION

According to the research methodology used, and taking into account the limitations of this study, it can be proposed that the most frequent color among the Spanish population is 3M1; the most common lightness group is 2; the most frequent hue group according to the 3D Master System is M and the most frequent chroma group is 1.5.

Application of the Social Appeal Scale to a Selected Spanish Population

PURPOSE

The aim of this study was to validate the Social Appeal Scale (SAS) among the Spanish general population, exploring the underlying dimensions of the construct assessed.

MATERIALS AND METHODS

The SAS test was applied to 555 participants between 16 and 75 years of age. The scale is divided into four dimensions: social competence (SC), intellectual ability (IA), psychologic adjustment (PA), and relationship satisfaction (RS).

RESULTS

The SAS (12 items) had a Cronbach alpha of .93, and SC had a Cronbach alpha of .83. For IA it was .85, for PA .87, and for RS .84.

CONCLUSION

Bearing in mind the limitations of the present study, it may be concluded that the Social Appeal Scale is a valid and reliable instrument to assess social perceptions related to changes in tooth color.

Natural Tooth Color Estimation Based on Age and Gender

PURPOSE

Assessment of the predictability of tooth color coordinates according to the CIELab system to estimate the color of the maxillary central incisor based on patient age and gender.

MATERIAL AND METHODS

The tooth color of one of the maxillary central incisors of 1361 Caucasian Spanish individuals aged 16 to 89 years, male and female, was measured using the Easyshade compact spectrophotometer. Color coordinates L*, C*, h*, a*, and b* were recorded according to age and gender.

RESULTS

The results obtained show that differences in age account for 45% of the total variation of the L (lightness) coordinate; 21% of the variation in coordinate a*, and 17% of the variation in coordinate b* is due to the same reason. At a confidence level of 95% it may be proposed that the mean estimated color difference (ΔE_ab *) between real natural color and that predicted by the linear regression model is between 6.4 and 6.9 units.

CONCLUSIONS

In this sample of Caucasians from Spain, teeth became darker yellow and more reddish with increasing age. The L* coordinate is most strongly related to tooth color in aging.

Effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles

In this work the effect of a SiO2 coating on the magnetic properties of Fe3O4 nanoparticles obtained by the sol-gel method is analyzed. Two sets of samples were prepared: Fe3O4 nanoparticles and Fe3O4@SiO2 core-shell composites. The samples display the characteristic spinel structure associated with the magnetite Fe3O4 phase, with the majority of grain sizes around 5-10 nm. At room temperature the nanoparticles show the characteristic superparamagnetic behavior with mean blocking temperatures around 160 and 120 K for Fe3O4 and Fe3O4@SiO2, respectively. The main effect of the SiO2 coating is reflected in the temperature dependence of the high field magnetization (μ(0)H = 6 T), i.e. deviations from the Bloch law at low temperatures (T < 20 K). Such deviations, enhanced by the introduction of the SiO2 coating, are associated with the occurrence of surface spin disordered effects. The induction heating effects (magnetic hyperthermia) are analyzed under the application of an AC magnetic field. Maximum specific absorption rate (SAR) values around 1.5 W g(-1) were achieved for the Fe3O4 nanoparticles. A significant decrease (around 26%) is found in the SAR values of the SiO2 coated nanocomposite. The different heating response is analyzed in terms of the decrease of the effective nanoparticle magnetization in the Fe3O4@SiO2 core-shell composites at room temperature.

Ni doped Fe3O4 magnetic nanoparticles

In this work, the effect of nickel doping on the structural and magnetic properties of Fe3O4 nanoparticles is analysed. Ni(x)Fe(3-x)O4 nanoparticles (x = 0, 0.04, 0.06 and 0.11) were obtained by chemical co-precipitation method, starting from a mixture of FeCl2 x 4H2O and Ni(AcO)2 x 4H2O salts. The analysis of the structure and composition of the synthesized nanoparticles confirms their nanometer size (main sizes around 10 nm) and the inclusion of the Ni atoms in the characteristic spinel structure of the magnetite Fe3O4 phase. In order to characterize in detail the structure of the samples, X-ray absorption (XANES) measurements were performed on the Ni and Fe K-edges. The results indicate the oxidation of the Ni atoms to the 2+ state and the location of the Ni2+ cations in the Fe2+ octahedral sites. With respect to the magnetic properties, the samples display the characteristic superparamagnetic behaviour, with anhysteretic magnetic response at room temperature. The estimated magnetic moment confirms the partial substitution of the Fe2+ cations by Ni2+ atoms in the octahedral sites of the spinel structure.

Vibrational and magnetic contributions to the entropy change associated with the martensitic transformation of Ni-Fe-Ga ferromagnetic shape memory alloys

Ferromagnetic shape memory alloys undergo a martensitic transformation accompanied by a change in the magnetic and vibrational properties. However, these property changes are not independent. In this paper, the interplay between magnetic and vibrational properties in the martensitic transformation entropy change has been analyzed for Ni-Fe-Ga ferromagnetic shape memory alloys. The martensitic transformation entropy change has a magnetic and a vibrational contribution, ΔS(p−>m)=ΔS(vib)(p−>m) + ΔS(mag)(p−>m). Using a mean field approximation for the magnetic entropy, the full entropy ΔS(p−>m) has been decomposed and the magnetic contribution ΔS(mag)(p−>m) calculated. Upon removing the magnetic term, the vibrational entropy ΔS(vib)(p−>m) does not change substantially in the composition range where T(M) is below T(C). This latter contribution to the martensitic transformation entropy change has been analyzed using a Debye distribution for the density of states and a proportion of Einstein modes that account for the anomalous phonon mode of the austenite.

Temperature dependence of magnetic susceptibility in the vicinity of martensitic transformation in ferromagnetic shape memory alloys

Temperature dependences of low-field quasistatic magnetic susceptibility in the vicinity of martensitic transitions in an NiFeGa alloy are studied both by experiment and analytically. Pronounced reversible jumps of the magnetic susceptibility were observed near the martensitic transition temperature. A general description of the temperature dependences of the susceptibility in ferromagnetic austenite and martensite phases and the susceptibility jump at the transition is suggested. As a result, the main factors governing the temperature dependences of the magnetic susceptibility in the magnetic shape memory alloys are revealed. The magnetic susceptibility jump value is found to be related to changes of: (i) magnetic anisotropy; (ii) magnetic domain wall geometrical constraints (those determined by the alignment and size of twin variants) and (iii) mean magnetic domain spacing.