Aesthetic outcomes of different materials for delayed, single-tooth restorations for immediately placed implants. A randomized controlled clinical trial.

OBJECTIVES: The aim of this study is to compare the aesthetic outcomes of metal porcelain (C), lithium disilicate (T1) and porcelain-layered zirconium (T2) immediate implant-supported single crowns in the anterior maxilla. MATERIALS AND METHODS: Forty-five immediate dental implants were provided for 45 patients that required the extraction of a single tooth in the anterior maxilla. A temporary prosthesis was provided at 8 weeks after placement followed by the final prosthesis at 24 weeks post-implantation. The patients were randomly allocated into 3 groups: 15 patients in the control group (C) received a metal-porcelain restoration, 15 patients (T1) received a lithium disilicate (LD) restoration and 15 patients (T2) received a porcelain-layered, zirconium (Z) restoration. Pink (PES) and White (WES) esthetic scores, radiographic bone levels, periodontal parameters and patient's esthetic satisfaction using a visual analogue scale (VAS) were evaluated at the time of final restoration placement (t0) and at 12-months post-loading (t12). RESULTS: No implants were lost during the duration of this study. Statistically significant higher WES and VAS scores (p < 0.05) were recorded in T1 vs C and T1 vs T2 groups respectively. Similar radiographic bone levels and periodontal parameters were recorded in all groups. CONCLUSION: Within the limitations of this study, it was concluded that T1 restorations provided better WES outcomes when compared to C restorations and better VAS scores when compared to T2 restorations at 12 months post-loading. Besides, different material interphases did not have an impact in PES, bone levels or periodontal parameters. CLINICAL RELEVANCE: There is limited data comparing aesthetic outcomes of implant supported single crowns made of different ceramic materials based on accepted and comparable indexes and the evaluation of the patient's perspective regarding these aesthetic outcomes.

Unveiling the Hidden Entropy in ZnFe2O4.

The antiferromagnetic (AFM) transition of the normal ZnFe2O4 has been intensively investigated with results showing a lack of long-range order, spin frustrations, and a "hidden" entropy in the calorimetric properties for inversion degrees δ ≈ 0 or δ = 0. As δ drastically impacts the magnetic properties, it is logical to question how a δ value slightly different from zero can affect the magnetic properties. In this work, (Zn1-δFeδ)[ZnδFe2-δ]O4 with δ = 0.05 and δ = 0.27 have been investigated with calorimetry at different applied fields. It is shown that a δ value as small as 0.05 may affect 40% of the unit cells, which become locally ferrimagnetic (FiM) and coexists with AFM and spin disordered regions. The spin disorder disappears under an applied field of 1 T. Mossbauer spectroscopy confirms the presence of a volume fraction with a low hyperfine field that can be ascribed to these spin disordered regions. The volume fractions of the three magnetic phases estimated from entropy and hyperfine measurements are roughly coincident and correspond to approximately 1/3 for each of them. The "hidden" entropy is the zero point entropy different from 0. Consequently, the so-called "hidden" entropy can be ascribed to the frustrations of the spins at the interphase between the AFM-FiM phases due to having δ ≈ 0 instead of ideal δ = 0.

Short Dental Implants (≤8.5 mm) versus Standard Dental Implants (≥10 mm): A One-Year Post-Loading Prospective Observational Study.

BACKGROUND: Recent data have shown that short dental implants can be the preferred treatment in most of cases of posterior atrophic alveolar ridges, offering higher survival and lower complication rates than long implants. The survival rates, stability, and marginal bone level changes were compared between short implants (7 and 8.5 mm) and standard-length implants (≥10 mm). METHODS: Prospective observational study in which adult patients requiring ≥1 osseointegrated implants to replace missing teeth were recruited consecutively. A clinical examination was performed on the day the definitive prosthesis was placed and after 6 and 12 months. Implant stability quotient (ISQ), marginal bone level (MBL) changes, and the correlation between these parameters and the characteristics of the implants were evaluated. RESULTS: A total of 99 implants were inserted (47 short, 52 standard) in 74 patients. The 12-month survival rate was 100%. ISQ values showed a similar pattern for both types of implants. No correlation was found between ISQ changes after one year and MBL values, nor between the latter and the characteristics of the implants. CONCLUSIONS: With clinical treatment criteria, shorter implants (7 and 8.5 mm in length) can be just as useful as standard-length implants in atrophic alveolar ridges, demonstrating similar rates of survival, stability, and crestal bone loss.

Influence of Fluoride Varnish Application on Enamel Adhesion of a Universal Adhesive.

Purpose: To study the effect of the varnish type, application time and surface polishing on the shear bond strength (SBS) of a universal adhesive in healthy and demineralized bovine enamel. Materials and Methods: 432 bovine primary central incisors were assigned to 18 groups according to enamel mineralization [healthy and demineralized], topical varnish [Clinpro White Varnish (CWV; 3M Oral Care) and Profluorid (PFV, Voco)], remineralization time [24 h or 21 days] and polishing or not of the enamel surface. Adhesion was tested using Futurabond M (Voco)+ and GrandioSO (Voco). Sheer bond strength (SBS) was measured and the fracture mode studied. The statistical analysis was performed using two-way ANOVA, Tukey's test, and Pearson's chi-squared test. Results: In healthy bovine enamel, CWV reduced SBS at 24 h and 21 days; polishing significantly improved SBS. PFV increased SBS in healthy enamel at 21 days and demineralized enamel at 24 h and 21 days; polishing had no effect on SBS. The application time and polishing of the enamel surface affected the behavior of varnishes with respect to SBS. There was a correlation between the type of fracture and the degree of mineralization as well as the timepoint of varnish application. Conclusions: Remineralization of demineralized enamel with fluoride varnishes permits the recovery of the bond strength obtained in healthy enamel. Of the two varnishes studied, PFV had the highest SBS and more uniform behavior, regardless of the application timepoint, degree of mineralization, and surface treatment of the enamel..

Iron oxide - clay composite vectors on long-distance transport of arsenic and toxic metals in mining-affected areas.

Mine wastes from abandoned exploitations are sources of high concentrations of hazardous metal(oid)s. Although these contaminants can be attenuated by sorbing to secondary minerals, in this work we identified a mechanism for long-distance dispersion of arsenic and metals through their association to mobile colloids. We characterize the colloids and their sorbed contaminants using spectrometric and physicochemical fractionation techniques. Mechanical action through erosion may release and transport high concentrations of colloid-associated metal(oid)s towards nearby stream waters, promoting their dispersion from the contamination source. Poorly crystalline ferrihydrite acts as the principal As-sorbing mineral, but in this study we find that this nanomineral does not mobilize As independently, rather, it is transported as surface coatings bound to mineral particles, perhaps through electrostatic biding interactions due to opposing surface charges at acidic to circumneutral pH values. This association is very stable and effective in carrying along metal(oid)s in concentrations above regulatory levels. The unlimited source of toxic elements in mine residues causes ongoing, decades-long mobilization of toxic elements into stream waters. The ferrihydrite-clay colloidal composites and their high mobility limit the attenuating role that iron oxides alone show through adsorption of metal(oid)s and their immobilization in situ. This may have important implications for the potential bioavailability of these contaminants, as well as for the use of this water for human consumption.