Influence of new complete dentures on the touch perception threshold and quality of life of edentulous patients.

OBJECTIVE: To evaluate the touch perception threshold of the alveolar mucosa and quality of life of edentulous patients before (T0) and 30 days after (T1) the insertion of new complete dentures. BACKGROUND: Touch perception is important so that edentulous patients can detect the position of complete dentures in their mouth. MATERIALS AND METHODS: This study included 32 complete denture wearers with good oral and systemic health and no temporomandibular disorders for at least 5 years. At each time point (T0 and T1), two tests were performed (touch perception threshold and quality-of-life scale). The touch perception threshold (Von Frey or Semmes-Weinstein test) was assessed using nylon monofilaments on the regions of the alveolar mucosa of the maxilla and mandible. The Oral Health Impact Profile for edentulous individuals (OHIP-EDENT) was administered to evaluate oral health-related quality of life. RESULTS: In the maxilla and mandible, the touch perception thresholds for all regions of the alveolar mucosa were significantly lower at T1 than at T0. The OHIP-EDENT mean scores showed that the overall quality of life was significantly better at T1 (3.6) than at T0 (4.7), and a significant improvement in quality of life was observed in all domains of the OHIP-EDENT at T1. For touch perception threshold, effect sizes ranged from 0.4 to 0.8; and for quality of life, effect sizes ranged from 0.4 to 1.0. CONCLUSIONS: New complete dentures reduced the touch perception threshold of the alveolar mucosa of both edentulous arches and improved individuals' quality of life.

Clinical reproducibility of different centric relation recording techniques in edentulous individuals: An observational cross-sectional study.

PURPOSE: To assess the reproducibility of four different centric relation (CR) recording techniques, and time spent performing each technique in edentulous individuals. MATERIALS AND METHODS: Four techniques were assessed: extraoral gothic arch (EOGA) tracing, intraoral gothic arch (IOGA) tracing, deglutition (D), and frontal manipulation with tongue elevation (FMTE). Twelve subjects participated in the study; four technique records were performed on each volunteer by the same operator. Each record was repeated three times, in the same period of the day, with a 30 min interval between each technique. The reproducibility of each technique was assessed by the tri-dimensional displacement of the position of the condylar housing (mandible condyle) to the wall of the condylar guide (glenoid cavity) in the semi-adjustable articulator (anteroposterior, mediolateral, and superior-inferior). The time spent on each technique was timed in seconds (from the beginning of each technique until the wax occlusion fixation). The analysis of variance (ANOVA) and the Tukey test were performed for anteroposterior displacement (two-way) and for time spent on CT recording techniques (one-way) (α < 0.05). Regarding mediolateral and superior-inferior displacements, the nonparametric Kruskal-Wallis was performed for the comparison between recording methods, whereas the Mann-Whitney test was performed for the comparison between sides (α < 0.05). RESULTS: The factor recording technique interfered with the anteroposterior displacement (ANOVA: α < 0.001; F = 11.396). The technique D (right side: 3.78 ± 0.69 mm; left side: 3.45 ± 0.74 mm) showed a statistically significant difference compared to the other techniques (EOGA: right side: 3.00 ± 0.00 mm; left side: 3.00 ± 0.00 mm; FMTE: right side: 2.81 ± 0.52 mm; left side: 2.82 ± 0.79 mm; IOGA: right side: 2.90 ± 0.65 mm; left side: 3.12 ± 0.44 mm). The time spent on the recording technique influenced the results (ANOVA: α < 0.001; F = 21.118). The IOGA (340.40 ± 163.41 s) and EOGA (285.93 ± 133.84 s) required more time compared to the D (86.00 ± 34.33 s) and FMTE (101.33 ± 36.72 s) techniques. CONCLUSION: Graphic recordings showed better reproducibility and accuracy of the position of the centric relation.

Complete Denture - Border Molding Technique Using a Laboratory Condensation Silicone Putty: Review.

During the fabrication of a complete denture, functional impression is taken. Literature studies show that polydimethylsiloxane (condensation silicone) has not been reported by United States dental schools to perform border molding. Thus, the purpose of this article is to review the functional impression technique when border molding is performed with a laboratory condensation silicone putty.

Removable Partial Denture - Functional Impression Techniques: Review.

The objective of this article is to concisely review the main clinical techniques used to make the functional impression to manufacture a removable partial denture. Through this review, the dentist can develop his clinical knowledge.

Effect of handling material on mechanical and optical properties of feldspathic porcelain.

OBJECTIVE: To evaluate the optical, chemical, and mechanical properties of feldspathic porcelain after handling with different instrument materials. MATERIAL AND METHODS: Feldspathic porcelain was manipulated with different spatula compositions: metal spatula (MS), plastic spatula (PS), and glass spatula (GS) for the fabrication of 30 (n = 10) disks. Contrast ratio (CR), translucency parameter (TP), and surface Knoop microhardness (KHN) were measured. The color change (ΔE00 ) was evaluated using the CIEDE2000 system. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used for surface analysis. Data were analyzed using one-way ANOVA and Tukey test (P < 0.05). RESULTS: All groups presented different morphological surfaces with higher presence of Al on the MS. PS group presented lower Al, Si, K than MS, and GS. Higher CR was observed for PS (0.734; P < 0.043), followed by MS (0.696; P < 0.043) and GS (0.65; P < 0.011). The highest TP (13.06) and KHN (386.27) were presented by GS (P < 0.001). MS and PS presented similar KHN results. The higher ΔE00 were found for plastic/metal comparison. Also, the L* values for the MS group (67.49) were lower than the other groups. CONCLUSION: The use of metal spatula promoted higher color alteration during feldspathic porcelain manipulation than did the other materials. Handling with glass instrument promoted higher microhardness than other spatula materials. CLINICAL SIGNIFICANCE: The effect of the material used for ceramic handling on feldspathic porcelain properties is often ignored. This study shows that the handling spatula material must be carefully chosen to avoid inadvertent changes to the feldspathic porcelain restoration.

Alcohol and light-polymerizing glaze effect on the physical and mechanical properties of a bisacrylate composite resin before and after immersion in chlorhexidine gluconate.

STATEMENT OF PROBLEM: The use of 0.12% chlorhexidine gluconate (CHX) may damage bisacrylate composite resin interim restorations, but whether they can be protected with an application of alcohol and/or the use of a glaze is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of applying a 70% alcohol solution on the physical and mechanical properties of a bisacrylate composite resin, with and without the application of a light-polymerizing glaze subjected to 0.12% CHX twice a day for 7 days. MATERIAL AND METHODS: Forty specimens of an autopolymerized bisacrylate composite resin were divided into 4 groups (n=10): Group C (without alcohol, without glaze), Group G (without alcohol, with glaze), Group A (with alcohol, without glaze), and Group AG (with alcohol, with glaze). All specimens were submitted to in vitro treatment with 0.12% CHX for 7 days, and tests of color alteration (ΔE00), microhardness, roughness, and surface were performed initially and after treatment. Data were submitted to analysis of variance (ANOVA) and the Tukey HSD test (α=.05). RESULTS: Group A had the lowest mean value of ΔE00 with a significant statistical difference from Group C. The groups with alcohol presented higher microhardness mean values compared with groups without alcohol in both periods of analysis, except for the groups with glaze in the final period. Group C showed higher mean roughness values in comparison with Group A in both periods. Group AG presented higher mean roughness values than Group G. Surface energy values did not vary significantly among groups, except between Groups C and A in the final period. CONCLUSIONS: The application of alcohol optimized the properties of the autopolymerized bisacrylate composite resin analyzed, with and without the application of glaze. Overall, the use of CHX changed the microhardness and roughness when the glaze was applied.

Comparison of different methods for obtaining centric relation: a systematic review.

The objective of this study was to compare techniques of different methods of obtaining centric relation to verify which technique generates the greatest reproducibility of the centric relation. The PubMed/MEDLINE, Cochrane Library, SciELO, Scopus, and Web of Science databases were searched for articles published up to May 15, 2018. The search terms were combinations of "dental centric relation" with each of the following terms (individually): "reproducibility of findings"; "jaw relation record"; "chin point"; "gothic arch"; "bimanual manipulation"; "swallowing"; and "jig." The inclusion criteria included clinical studies in English that had to compare at least 2 techniques representing different methods for obtaining centric relation (based on the reproducibility of the centric relation) in individuals without temporomandibular dysfunction; and studies performed in individuals with complete or nearly complete dentition or complete edentulism. Methods (techniques) included in this study were guided methods (chin point guidance and bimanual manipulation); graphic methods (intraoral and extraoral gothic arch tracing); and physiologic methods (swallowing and tongue retrusion along the palate). A total of 1638 articles were identified. After the inclusion and exclusion criteria were applied, 7 articles were included in this review. None of the reviewed studies evaluated edentulous individuals. Two articles compared physiologic methods with guided methods; one concluded that the swallowing technique generates greater variability than guided methods, and the other concluded that there was no difference between the swallowing technique and chin point guidance. Of 5 articles comparing intraoral gothic arch tracing with guided methods, 2 showed similar results between different methods, 2 showed superior results for gothic arch tracing, and 1 showed superior results for the guided methods. Based on the guided methods and swallowing technique, it is not possible to conclude which technique can generate the greatest reproducibility of the centric relation. It is possible to suggest that in most cases intraoral gothic arch tracing is superior or equivalent when compared to guided methods.

Titanium versus ceramic implants for overdentures: a meta-analysis of prospective studies.

The aim of this study was to compare the use of titanium and ceramic implants for overdentures in terms of their failure rates, surface treatments, and marginal bone loss (MBL). The literature was searched using the PubMed, Scopus, and Cochrane databases up to October 2019. Clinical studies in which ceramic and titanium implants for overdentures were compared in terms of their failure rates, surface treatments, and MBL were included in the meta-analysis. The meta-analysis was performed based on the Mantel-Haenszel and inverse variance methods using a fixed-effects model and 95% confidence intervals. A total of 2747 publications were identified after the exclusion of duplicate articles. Fifteen were selected for full-text reading, and 2 were included in the review. Each of the 2 studies initially enrolled 24 patients, and a total of 38 patients (mean age of 62 years) were evaluated at the 1-year follow-up. A total of 112 titanium implants (success rate of 71.1%) and 146 ceramic implants (success rate of 65.9%) were placed. Twenty titanium implants failed, and an associated MBL of 0.15 mm was observed. For ceramic implants, 42 failures occurred, and an associated MBL of 0.33 mm was observed. Titanium implants provided better clinical results (less MBL and lower failure rate) for the support of overdentures than did ceramic implants.

Influence of thermocycling and disinfection on the color stability and hardness of thermoplastic sheets used for occlusal splint fabrication.

The aim of this study was to compare PETG/TPU (polyethylene terephthalate glycol/thermoplastic polyurethane) with PETG (polyethylene terephthalate glycol), based on color stability and microhardness. Sixty circular specimens (10 mm in diameter × 3 mm thick) were fabricated (30 PETG/TPU and 30 PETG). The specimens in both groups were submitted to 2000 thermal cycles in alternating baths of 60 seconds at 5°C ± 1°C and 55°C ± 1°C. The specimens were then divided into subgroups (n = 10) that were disinfected 15 minutes per day for 60 days in 1 of 3 solutions: liquid soap, 2% chlorhexidine, or Listerine. Color change (∆E*) and Knoop microhardness tests were performed at baseline (T0), after thermocycling (T1), and after disinfection (T2). Analysis of variance (ANOVA) and Tukey test were used (P < 0.05). ANOVA showed that there was no statistically significant difference in color change between the 2 materials after thermocycling (∆E*1) or after disinfection (∆E*2), regardless of the disinfectant. Intragroup comparisons (Listerine, liquid soap, and 2% chlorhexidine) of the 3 PETG/TPU groups or 3 PETG groups after disinfection revealed no statistically significant difference for microhardness. Comparison of PETG/TPU with PETG based on the overall mean microhardness showed that the PETG/TPU had a significantly greater mean surface hardness value (P < 0.05). The Tukey test revealed statistically significant increases in microhardness at T1 and T2 for PETG/TPU and PETG so that T0 < T1 < T2 (P < 0.05). Both thermoplastic materials demonstrated an increase in hardness after thermocycling and after disinfection, and both showed similar color changes regardless of the disinfection method. Based on the color evaluation, the liquid soap proved to be the best option for disinfection of PETG/TPU and PETG, because the color change (∆E* value) was clinically acceptable for both materials.

Comparison of the Morse Cone Connection with the Internal Hexagon and External Hexagon Connections Based on Microleakage - Review.

The gap formed at the abutment-implant interface brings about a bacterial colonization. In addition, a bacterial reservoir can be established within the implant. The build-up of microorganisms around the implant can cause soft tissue infections and bone loss around the implant, which can lead to implant failure. Our literature review aimed to evaluate the infiltration at the implant-abutment interface, comparing the Morse cone connection with the external hexagon and internal hexagon connections. A literature search using the PubMed database was performed on March 24, 2021. The search terms were combinations of "Morse cone" or "Morse taper" with each of the following terms (individually): "microleakage", "leakage", "infiltration", and "penetration". The inclusion criterion was in vitro studies comparing the Morse cone with the external hexagon and/or internal hexagon, based on infiltration at the implant-abutment interface. The exclusion criterion was the evaluation of microleakage at the implant-abutment interface after applying a sealant over this region. The search was expanded as needed. There was no limit on the year of publication, and only articles written in English were included. In addition, references cited in included articles were also included in this review when they were appropriate. This literature review concluded that, in most cases, the microleakage in the Morse cone connection was lower when compared with the external hexagon and internal hexagon connections.

Effect of surface treatment on the retention of zirconia crowns to tooth structure after aging.

OBJECTIVE: To evaluate the effect of different surface treatments on the retention between zirconia crowns and tooth structure after in vitro aging. MATERIALS AND METHODS: Human third molars (n = 44) received crown preparations and CAD/CAM zirconia crowns were manufactured. Specimens were divided into two groups: no aging, control (NAC, n = 11) or aging (A, n = 33). NAC were bonded with universal adhesive (UA). Aged specimens were divided into three subgroups (n = 11) according to surface treatment: Control: no abrasion + UA; Alumina: alumina abrasion + UA; Silica: tribochemical silica coating + UA. The crowns were cemented with dual-cure resin cement. Specimens in group A were aged by a combination of mechanical, thermal, and pH cycling. Retention strength values were obtained by tensile tests and results were analyzed by one-way analysis of variance (ANOVA) and Tukey test (P < .05). RESULTS: Aging decreased the retention strength in control specimens (P < .001). Surface treatment improved the retention strength of aged specimens (P < .001), with similar results between alumina and tribochemical silica coating. CONCLUSION: The chemical interaction between the universal bonding system and zirconia's surface was not sufficient to withstand artificial aging. Tribochemical silica coating did not promote additional retention in comparison to alumina blasting. CLINICAL SIGNIFICANCE: The long-term retention of translucent zirconia crowns to tooth structure using phosphate-based materials is improved by means of mechanical surface treatments such as alumina blasting and tribochemical silica coating.

Influence of the ferrule effect on the failure of fiber-reinforced composite post-and-core restorations: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: The survival and/or success of post-retained restorations is influenced by the amount of residual coronal structure, known as the "ferrule effect." PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate whether the presence or absence of the ferrule effect influences the failure rate of fiber-reinforced composite post-and-core restorations. MATERIAL AND METHODS: A comprehensive review of the literature was performed using the PubMed/Medline, Embase, Scopus, and Cochrane Library databases for articles published up to May 2018. The risk ratio with 95% confidence interval was estimated using the Mantel-Haenszel method. Potentially eligible studies were selected based on the reading of the abstracts and full text of prospective clinical trials, randomized clinical trials, or prospective randomized studies, all with a minimum of 10 participants in each group, with a follow-up period longer than 6 months, and published in English. RESULTS: Of the 380 studies retrieved, 4 were included in this meta-analysis. A total of 297 teeth were evaluated, 157 with a ferrule and 140 without a ferrule. The mean survival rate was 88.35% in the ferrule group and 78.05% in the nonferrule group. No statistically significant difference was noted in the general failure analysis (risk ratio: 0.71 [95% confidence interval: 0.47 to 1.06]; P=.09), although a higher number of failures occurred in nonferrule restorations. More controlled and randomized clinical trials are needed to establish a clinical protocol for the use of post-retained restorations. CONCLUSIONS: Despite the limited number of available studies, the results of this meta-analysis suggest that the ferrule effect does not significantly reduce the failure rate in fiber-reinforced composite post-and-core restorations.

Effects of 50- and 70-Gy radiation doses on polymethyl methacrylate denture bases.

The aim of this study was to evaluate the flexural strength and Knoop microhardness of the polymethyl methacrylate (PMMA) used in dental prostheses after receiving therapeutic radiation doses of 50 and 70 Gy. Thirty-six acrylic resin plates measuring 65.0 × 10.0 × 3.3 mm were fabricated and polymerized using a microwave. The specimens were randomly divided into 3 groups (n = 12): group 1, which received no radiation; group 2, which received 1 fractioned dose of 2 Gy per day, 5 days per week, for 5 weeks, totaling 50 Gy; and group 3, which received 1 fractioned dose of 2 Gy per day, 5 days per week, for 7 weeks, totaling 70 Gy. All specimens remained in ballistic gel at a temperature of 37°C throughout the study. Afterward, the specimens underwent flexural strength and Knoop microhardness tests. All data were analyzed using analysis of variance and Tukey post hoc test (P < 0.05). For flexural strength, there was a statistically significant difference between groups 1 and 2 (P = 0.012) and between groups 1 and 3 (P = 0.048). For Knoop microhardness, there was a difference between groups 1 and 2 (P = 0.001) and between groups 1 and 3 (P = 0.006). For both flexural strength and microhardness, groups 2 and 3 showed greater values than group 1. Therapeutic radiation doses of 50 and 70 Gy increased the flexural strength and Knoop microhardness of PMMA used in dental prostheses.

Marginal and internal adaptation of lithium disilicate partial restorations: A systematic review and meta-analysis.

AIM: The aim of this meta analysis was to evaluate the influence of the processing method on the marginal and internal gaps of lithium disilicate inlays/onlays. SETTINGS AND DESIGN: A systematic literature review was conducted using the PubMed/Medline, Embase, Scopus, and Cochrane Library databases. This review was registered on the PROSPERO platform. MATERIALS AND METHODS: The studies were selected according to the marginal and internal gaps of two different fabrication methods for lithium disilicate (milled and pressed). STATISTICAL ANALYSIS USED: The meta analysis was performed based on the Mantel-Haenszel and inverse variance methods, using the random effects model and a 95% confidence interval. RESULTS: From all databases, 127 studies were identified. Four in vitro studies were included in the qualitative analysis and three in the meta analysis. Moreover, 197 restorations were evaluated (103 pressed and 94 milled). During the evaluation of only the internal gap, there was a statistically significant difference favoring the pressed technique (P = 0.002). There was no statistically significant difference in the analyses of the marginal gap (P = 0.530) and the total gap (P = 0.450). CONCLUSION: Both the techniques provided acceptable marginal and total gaps, although the pressed technique revealed a more favorable internal adaptation than the milled onlays/inlays.

Evaluation of the level of cortisol, capillary blood glucose, and blood pressure in response to anxiety of patients rehabilitated with complete dentures.

BACKGROUND: The aim was to analyze the levels of stress of edentulous patients through the state-trait anxiety inventory (STAI) and salivary flow through the visual analogue scale (VAS) xerostomia questionnaire, as well as analyze the levels of cortisol, capillary blood glucose, and blood pressure (BP) before and after the installation of complete dentures. METHODS: Fifty patients were evaluated. The STAI and VAS xerostomia questionnaire were applied before the installation of the prosthesis, on the day of its installation, and 1 month after the last recall visit. The BP measurement, as well as salivary and blood collections, were performed before the installation of the prothesis, and 1 month after the last recall visit. Data from the VAS xerostomia questionnaire and cortisol levels were submitted to ANOVA and the Tukey test (P = .05). Data from the STAI, as well as blood glucose and BP levels, were submitted to the Chi-square test (P = .05). The correlation between cortisol and blood glucose and between cortisol levels and BP was analyzed. RESULTS: There was no statistically significant association between the questions of the VAS xerostomia questionnaire, STAI-state and STAI-trait scores, or the periods analyzed. However, the cortisol level collected in the morning decreased after the installation of the prosthesis. There was a correlation between cortisol and blood glucose and BP levels. CONCLUSIONS: The installation of complete dentures was beneficial for patients since it was probably responsible for the cortisol level reduction.

Can Nonthermal Plasma Improve the Adhesion between Acrylic Resin for Ocular Prostheses and Silicone-Based Relining Material?

PURPOSE: To investigate the influence of nonthermal plasma (NTP) treatment on the tensile bond strength between heat-polymerized acrylic resin for ocular prostheses and silicone reliner, with and without the use of an adhesive primer. MATERIALS AND METHODS: One-hundred and sixty-four acrylic resin specimens were fabricated and randomly distributed into four groups according to the type of surface treatment: Sofreliner Primer, NTP, Sofreliner Primer + NTP, and NTP + Sofreliner Primer. Two specimens interposed with relining material (Sofreliner) formed one test sample to perform the tensile bond strength tests, before (initial) and after storage (final) in saline solution (37°C, 90 days, n = 10). Surface characterization was performed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The failure type was classified as cohesive, adhesive, or mixed. The data were analyzed statistically using the two-way ANOVA and Tukey test, as well as the chi-squared test (α = 0.05), Bonferroni correction (α = 0.005), and Spearman correlation coefficient (α = 0.05). RESULTS: The SEM and EDS analyses showed the presence of a thin, homogenous organic film in the groups treated with NTP. The NTP + Sofreliner Primer group presented the largest bond strength mean values in the initial period (p < 0.05). Sofreliner Primer and NTP + Sofreliner Primer groups presented the first and second largest tensile bond strength mean values in the final period (p < 0.05), respectively. NTP + Sofreliner Primer group also had the largest number of cohesive (70%, initial) and mixed (90%, final) failures. CONCLUSIONS: The NTP treatment performed before the primer application enhanced the bond between the acrylic resin ocular prosthesis and the Sofreliner silicone-based reliner, even after 90 days of immersion in saline solution.

Clinical outcome of removable prostheses supported by mini dental implants. A systematic review.

INTRODUCTION: For many years, edentulous patients have had no other option than conventional dentures to reestablish their oral function. To avoid the need for bone graft surgery, some professionals have suggested the use of mini dental implants (MDIs) to support prostheses. The MDIs are narrow implants, ranging approximately from 1.8 to 2.9 mm in diameter. Recently, the promising results of mini implants regarding osseointegration and patient satisfaction have led clinicians to accept them as a definitive treatment option. OBJECTIVE: Therefore, the proposition of this systematic review was to assess information on the outcomes of MDIs supporting removable prostheses. METHODS: The PubMed and Cochrane databases were searched for articles published before September 2017, which yielded a total of 774 studies for analysis. After exclusion and inclusion criteria, 22 prospective studies were included in this systematic review. RESULTS: Most mini implants were placed in a flapless single-stage surgery and loaded immediately. Most studies reported failures in the first year and prosthetic complications. The mean survival rate of the selected studies was 95.6%, and mean follow-up was 22.8 months. CONCLUSION: The MDI-supported removable prostheses successfully improved patients' chewing and speaking ability, quality of life, and satisfaction, suggesting that MDIs are a viable and safe option to support removable prostheses in the mandibular arch.

Effect of nonthermal plasma on the properties of a resinous liner submitted to aging.

STATEMENT OF PROBLEM: The properties, such as softness and viscoelasticity, of a resinous reliner can deteriorate and extrinsic elements can become incorporated, making surface protection of the reliner material essential. PURPOSE: The purpose of this in vitro study was to evaluate the effect of low temperature plasma on Coe-Soft resinous reliner, submitted to aging in artificial saliva for up to 180 days. Sorption, solubility, Shore A hardness, surface energy, and topographic characteristics were analyzed by scanning electronic microscopy (SEM) and energy-dispersive spectroscopy (EDS). MATERIAL AND METHODS: Forty-four specimens were fabricated and distributed in 2 groups: nonplasma reliner (control group) and reliner with plasma (plasma group). The plasma was applied with a mixture of 70% hexamethyldisiloxane, 20% O, and 10% Ar. Total work pressure was maintained at a constant 20 Pa for 30 minutes of deposition. The specimens were analyzed before and after aging in an incubator with immersion in artificial saliva for 30, 90, and 180 days. The quantitative data were submitted to 2-way ANOVA and the Tukey test (α=.05), while qualitative data were compared visually. RESULTS: The control group presented lower Shore A hardness values only in the initial period, and surface energy increased with aging for both groups until 90 days. Greater sorption percentage values were encountered at 180 days in the plasma group. Greater solubility values were encountered in the control group in all periods. CONCLUSIONS: Plasma is an option for the protection of the material studied because the deposited film remained on the surface of the reliner material after aging.

Initial investigation of the corrosion stability of craniofacial implants.

STATEMENT OF PROBLEM: Although craniofacial implants have been used for retention of facial prostheses, failures are common. Titanium undergoes corrosion in the oral cavity, but the corrosion of craniofacial implants requires evaluation. PURPOSE: The purpose of this in vitro study was to investigate the corrosion stability of commercially pure titanium (CP Ti) exposed to simulated human perspiration at 2 different pH levels (5.5 and 8). MATERIAL AND METHODS: Fifteen titanium disks were divided into 3 groups (n=5 per group). The control group was subjected to simulated body fluid (SBF) (control). Disks from the 2 experimental groups were immersed in simulated alkaline perspiration (SAKP) and simulated acidic perspiration (SACP). Electrochemical tests, including open circuit potential (3600 seconds), electrochemical impedance spectroscopy, and potentiodynamic tests were performed according to the standardized method of 3-cell electrodes. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α=.05). RESULTS: Simulated human perspiration reduced the corrosion stability of CP Ti (P<.05). The SBF group presented the lowest capacitance values (P<.05). SAKP and SACP groups showed increased values of capacitance and showed no statistically significant differences (P>.05) from each other. The increase in capacitance suggests that the acceleration of the ionic exchanges between the CP Ti and the electrolyte leads to a lower corrosion resistance. SAKP reduced the oxide layer resistance of CP Ti (P<.05), and an increased corrosion rate was noted in both simulated human perspiration groups. CONCLUSIONS: Craniofacial implants can corrode when in contact with simulated human perspiration, whereas alkaline perspiration shows a more deleterious effect. Perspiration induces a more corrosive effect than simulated body fluid.

The Effect of Surface Treatment on Shear Bond Strength between Y-TZP and Veneer Ceramic: A Systematic Review and Meta-Analysis.

PURPOSE: The objective of this systematic review with meta-analysis was to evaluate surface treatment in yttria-stabilized tetragonal zirconia polycrystal ceramic (Y-TZP) on the shear bond strength (SBS) values between Y-TZP (core ceramic) and veneer ceramic, compared to untreated specimens. MATERIALS AND METHODS: This review was registered at PROSPERO platform under the number CRD42016036493. The systematic review of the extracted publications was performed to compare the effect of surface treatment on SBS between Y-TZP ceramic and veneering ceramic. A comprehensive review of the literature from the earliest available dates through January 2017 was performed in the PubMed/Medline, Embase, Scopus, and Cochrane Library databases. RESULTS: A total of 15 studies were identified for the inclusion of data, with only in vitro studies. A random-effect model found statistically significant differences between untreated and treated surfaces of Y-TZP (p < 0.00001; MD: 2.84; 95% CI: 2.19 to 3.49). In another analysis, a random-effect model found statistically significant differences between the groups that only performed the associations of treatments and control group (p < 0.00001; MD: 3.19; 95% CI: 2.11 to 4.28). CONCLUSIONS: Surface treatment in Y-TZP improved the values of SBS between the Y-TZP and veneer ceramic. The associations between two or more treatments also showed positive effect on the bond strength due the cumulative effect of the treatments.