Corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloys in different storage environments

Statement of problem. Removable partial dentures are affected by fatigue because of the cyclic mechanism of the masticatory system ansi frequent insertion and removal. Titanium and its alloys have been used in the manufacture of denture frameworks; however, preventive agents with fluorides are thought to attack titanium alloy surfaces.Purpose. This study evaluated, compared, analyzed the corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloy in different storage environments.Material and methods. For each metal, 33 dumbbell rods, 2.3 mm in diameter at the central segment, were cast in the Rematitan system. Corrosion-fatigue strength test was carried out through a universal testing machine with a load 30% lon er than the 0.2% offset yield strength and a combined influence of different: environments: in air at room temperature, with synthetic saliva, and with fluoride synthetic saliva. After failure, the number of cycles were recorded, and fracture surfaces were examined with on SEM.Results. ANOVA and Tukey's multiple comparison rest indicated that Ti-6Al-4V alloy achieved 21,269 cycles (SD = 8,355) against 19,157 cycles (SD = 3,624) for the commercially purr Ti. There were no significant differences between either metal in the corrosion-fatigue life for dry specimens, but when the solutions were present, the fatigue life was significantly reduced, probably because of the product-ion of corrosion pits caused by superficial reactions.

Tooth Discoloration Induced by Endodontic Phenothiazine Dyes in Photodynamic Therapy

Objective: This study sought to assess if discoloration of tooth structures occurs after photodynamic therapy (PDT) and to determine the efficacy of a protocol to remove the photosensitizers. Background data: PDT has been used in root canal treatment to enhance cleaning and disinfection of the root canal system. PDT uses a low power laser in association with a dye as a photosensitizer. Photosensitizers can induce staining of the dental structures, resulting in an unaesthetic appearance. Methods: Forty teeth were randomly divided into four groups according to the photosensitizer used and pre-irradiation time: 0.01% methylene blue for 5 min (MB5); 0.01% methylene blue for 10 min (MB 10); 0.01% toluidine blue for 5 min (TB5); and 0.01% toluidine blue for 10 min (TB 10). Specimens were irradiated with a 660 nm diode laser with a 300 mu m diameter optical fiber, at 40 mW power setting for 3 min. Immediately after, the photosensitizers were removed with Endo-PTC cream +2.5% sodium hypochlorite (NaOCl). The shade was measured by a Vita Easyshade spectrophotometer based on the CIELAB color system (L*a*b* values) at three different experimental times: before PDT (T0), immediately after PDT (T1), and after removal of the photosensitizer (T2). Results: The results showed a decrease in the averages of the L*a*b* coordinate values after PDT (T1) in all the groups, when compared with the number at T0, with a significant statistical difference in group MB10. After photosensitizer removal (T2), all the values of the coordinates increased with significant statistical differences (p < 0.05) between T1 and T2 in L* and a*. Conclusions: It can be concluded that both methylene blue and toluidine blue dyes cause tooth discoloration, and that Endo-PTC cream associated with 2.5% NaOCl effectively remove these dyes, regardless of the pre-irradiation time used for PDT.

Effect of the iron doping on the thermal decomposition of the polymeric precursor for the titanium dioxide powder synthesis

The Polymeric Precursor Method has proved suitable for synthesizing reactive powders using low temperatures of calcination, especially when compared with conventional methods. However, during the thermal decomposition of the polymeric precursor the combustion event can be releases an additional heat that raises the temperature of the sample in several tens of degrees Celsius above the set temperature of the oven. This event may be detrimental to some material types, such as the titanium dioxide semiconductor. This ceramic material has a phase transition at around 600 ° C, which involves the irreversible structural rearrangement, characterized by the phase transition from anatase to rutile TiO2 phase. The control of the calcination step then becomes very important because the efficiency of the photocatalyst is dependent on the amount of anatase phase in the material. Furthermore, use of dopant in the material aims to improve various properties, such as increasing the absorption of radiation and in the time of the excited state, shifting of the absorption edge to the visible region, and increasing of the thermal stability of anatase. In this work, samples of titanium dioxide were synthesized by the Polymeric Precursor Method in order to investigate the effect of Fe (III) doping on the calcination stages. Thermal analysis has demonstrated that the Fe (III) insertion at 1 mol% anticipates the organic decomposition, reducing the combustion event in the final calcination. Furthermore, FTIR-PAS, XRD and SEM results showed that organic matter amount was reduced in the Fe (III)-doped TiO2 sample, which reduced the rutile phase amount and increased the reactivity and crystallinity of the powder samples.

Fotocatálise heterogênea de enterococcus faecalis e pseudomonas aeruginosa desencadeada pela ação da luz UV e branca em espátulas com revestimento de nanopartículas TiO2 e Ag

Nanotechnology, the science of minuscule, has developed products which are able t o manipulate atoms and molecules that could be applied in the sterilization process of dental instruments. Objetives: The objective of the present study was to evaluate the self-cleaning action of TiO2 and Ag nanoparticles coating on dental instruments by the photocataliys process under UV and visible light irradiation. Material and method: Microbiologic tests were done using dental cement spatulas coated with TiO2 and Ag nanoparticles (one or three layers), and contaminated with 10 mcrl of Pseudomonas aeruginosa and Enterococcus faecalis, respectively. After contamination, they were exposed to ultraviolet light and visible light for 120 minutes. Next, they were transferred to and stored in test tubes with BHI (Brain Heart Infusion) and incubated in 35 to 37 °C. Checking times for bacterial growth and for control and retrieval tests were done at: 24, 48, 72 and 96 hours. Result: The Pseudomonas aeruginosa was inactive after 120 minutes of ultraviolet light irradiation, thus confirming the heterogeneous photocatalytic activity of TiO2 and Ag. The Pseudomonas aeruginosa was not inactivated under visible light irradiation and the Enterococcus faecalis was not inactivated under UV and visible light irradiation of the dental cement spatulas coated with TiO2 and Ag nanoparticles in the readings to 96 hours, showing bacterial growth. Conclusion: There were no influence of one or three layers of TiO2 and Ag nanoparticles coating of the spatulas in the results. The heterogeneous photocatalysis activity of TiO2 and Ag under UV light irradiation was confirmed for Pseudomonas aeruginosa but not under visible light. Enterococcus faecalis did not confirmed the photocatalytics activity of TiO2 and Ag under UV light irradiation and visible lights irradiation.

Orbital wall reconstruction with titanium mesh:Retrospective study of 24 patients

The aim of this study was to evaluate the efficacy and safety of traumatic orbital defect reconstruction with titanium mesh. A retrospective study was made. Evaluations were made after a minimum postoperative follow-up of 12 months, looking for the main complications. Twenty-four patients were included in this evaluation; 19 were male (79.1%) and 5 (20.8%) were female. The main injury etiology was vehicle accidents (50%) followed by other causes. Fourteen patients (58.3%) presented orbital floor fractures, and 10 had more than one wall fractured (41.6%). Permanent infraorbital nerve hypoesthesia was observed in two patients (8.3%), enophthalmos occurred in five patients (20.8%), and exophthalmos was found in two patients (8.3%). Four patients (16.6%) still presented evidence of residual prolapsed intraorbital content, and one of those needed further surgical correction; sinusitis occurred in one patient (4.1%). Titanium mesh is a reliable option for orbital reconstruction, despite some complications found in this sample.

Aplicação do laser Er,Cr:YSGG em periodontia e implantodontia: revisão de literatura

Lasers are widely used tools in many therapeutic modalities in medical lasers and can be divided into low and high intensity. For the treatment of periodontal disease, lowintensity lasers are related to reduce the number of bacteria and to induce inflammatory and analgesic properties. The high intensity lasers can be used in surgical procedures, improving hemostasis, promoting more accurate cuts, removal of dental calculus as well as thermomechanical and photochemical interactions with tissue. The high-intensity laser Erbium impregnated with chromium: YSGG laser has shown satisfactory results when applied in endodontic, restorative denstistry, surgical procedures and non-surgical periodontal treatment. The purpose of this review is to evaluate the studies that investigated the effects of Er, Cr: YSGG laser on the morphology and biocompatibility of titanium and root surfaces irradiated with these lasers, even beyond the effect on the treatment of periodontitis and periimplantitis.

Two-and tridimensional analysis of periapical repair after endodontic surgery

Objective The aim of this study was to evaluate repair after endodontic surgery using two- and tridimensional imaging methods. Materials and methods Periapical radiographs and cone beam computed tomography (CBCT) were performed before the surgeries and after 48 h (baseline), 4 months, and 8 months. The area (square millimeters) of periapical lesions in CBCT and in radiographs was compared regarding the percentage of repair. In the CBCT, multiple areas were converted to volume. Repeated-measures analyses and paired t tests (α=0.05) were used to compare the methods. Correlation coefficients were calculated between the periods of evaluation within the CBCT volumetric analysis. Bland-Altman plots were used to compare the methods, based on the 95 % limits of agreement for the difference of the means. Results Baseline showed a larger lesion volume (192.54 mm3 ) than 4-month (79.79 mm3 ) and 8-month (47.51 mm3 ) periods. No differences were found in the percentage of repair in the first 4 months and after 8 months. The volumetric analysis showed a higher percentage of repair when the first and last 4 months were compared. No differences were found in the percentage of repair by area in the CBCTs. Repair of 73 % was obtained after 8 months. Similar results were observed by the Bland-Altman agreement analyses. Conclusions The percentage of repair varied after 8 months, when lower values were obtained by volumetric evaluation. Clinical relevance Considering the outcome at follow-up periods over 4 months, tridimensional evaluation by CBCT is more capable of determining the absence of periapical bone repair than conventional two-dimensional radiographs. Therefore, the use of CBCT would be suggested only for more complex cases with slower evolution of repair or for the association of factors that make prognosis difficult after surgery.

Instrumentation of dental implants: a literature review

The aim of this study was to review the literature on the systems used to decontaminate the implant's surface. Different instruments have been proposed, but there is no agreement in the literature about which methods would be more efficient with no damage to the implant surface. It was reported the use of plastic, carbon fiber, stainless-steel and titanium curettes and also the use of other systems such as ultrasonic points with different tips, rubber cups and air abrasion. Literature review: In most of the studies, the injury caused on the titanium surface at the time of instrumentation was examined. In others, the cell adhesion on the titanium dental implants following instrumentation of the implant surface was observed. Moreover, to enhance cleaning around implants, ultrasonic systems were recently tested. Conclusion: Metal instruments can lead to major damage to implant surface, therefore, they are not indicated for decontamination of dental implants surfaces. Furthermore, non-metallic instruments, such as plastic curettes, rubber cups, air abrasion and some ultrasonic systems seem to be better choices to remove calculus and plaque of the sub- and supra-gingival peri-implant area. It is noteworthy that more studies evaluating the effects of these systems are required to establish best practices to be used in the treatment of patients with dental implants.

Comparative analysis of three rotary instruments used for coronal pre-enlargement in radicular dentin thickness and root canal area of mandibular molars

Purpose: The purpose of this study was to evaluate the increase of the cervical area and dentin thickness in mesial and distal walls of the mesial canals from mandibular molars after the use of LA Axxess (LA), CP Drill (CP) and Gates-Glidden (GG) rotary instruments. Material and Methods: Sixty root canals from thirty mandibular first molar were sectioned 3 mm below the cement-enamel junction, divided in 3 groups (n = 20 root canals, each) according to rotary instrument used, and the cervical images were captured before and after pre-enlargement instrumentation. The increase of the instrumented cervical area (mm2) and the dentin removal thickness (mm), at mesial and distal walls were calculated using Image tools software, by comparison of images. Data were analyzed by ANOVA and Tukey tests (p=0.05). Results: All rotary instruments promoted thickness reduction in dentin walls. In mesial wall, all rotary instruments promoted similar thickness reduction of dentinal wall and did not differ from each other (p>0.05). In distal wall, LA Axxess instrument promoted higher dentin thickness reduction than other groups (p<0.05). The three rotary instruments promoted different increase at the instrumented cervical area (p<0.05), LA promoted the highest increase area and GG and CP presented similar results. Conclusion: LA 20/0.06 promoted the highest thickness reduction in distal wall and increase of cervical area of root canal. On the other hand, CP was the safest instrument, with lower dentin removal of distal wall and similar increased area to GG.

Effect of two formulations of 10% sodium ascorbate on fracture resistance of endodontically treated tooth submitted to dental bleaching with hydrogen peroxide associated titanium dioxide nanoparticles

Purpose: This study evaluated the effect of 10% sodium ascorbate (10SA), in gel (10SAg) or aqueous solution (10SAs) formulations, on fracture resistance of endodontically treated tooth submitted to dental bleaching procedures with 15% hydrogen peroxide associated with titanium dioxide (15HP-TiO2) nanoparticles and photoactivated by LED-laser. Material and methods: Forty maxillary premolars were endodontically-treated and embedded in acrylic resin up to the cement-enamel junction. The specimens were divided into four groups (n=10): G1 (negative control): no bleaching, coronal access restored with composite resin; G2 (positive control): three dental bleaching sessions using 15HP-TiO2 and LED-laser photoactivation and restored with composite resin (positive control); G3 (10SAg): similar procedures to G2, but applied 10SA, in gel formulation, for 24 hours before restoration; G4 (10SAs): similar procedures to G3, but applied 10SA, in aqueous solution formulation. The 15HP-TiO2 was applied on buccal and lingual surfaces of the crown tooth and inside the pulp chamber and photoactivated by LED-laser. Between each bleaching session, the teeth were maintained in artificial saliva, at 37oC, for 7 days. In sequence, the teeth were submitted to fracture resistance testing using an eletromechanical machine test. The data was analyzed using Kruskal Wallis test (p = 0.05) Results: There are no differences significant among the groups in relation to fracture resistance of endodontically treated teeth (p>0.05). Conclusions: The use of 10% sodium ascorbate, in gel or aqueous solution formulations, did not interfered on the fracture resistance teeth after dental bleaching using 15HP-TiO2 and LED-laser photoactivation.

Ethanol is inefficient to remove endodontic sealer residues of dentinal surface

Endodontic sealer residues on dentinal surface have negative effects on adhesion of adhesives system and/or can cause discoloration of the dental crown. Objective: To evaluate the efficacy of 95% ethanol in removal of residues of epoxy-based (AH Plus), methacrylate-based (Epiphany SE) or calcium-based (Sealapex) sealers on dentinal surface. Material and methods: Thirty-two bovine incisor dental crown fragments (0.5 mm x 0.5 mm) were treated with 17% EDTA and 2.5% NaOCl. The specimens were divided into three experimental groups (n = 10): G1 (AH Plus), G2 (Epiphany SE) and G3 (Sealapex). In each group was applied a coating of one endodontic sealer type and were left undisturbed for 5 minutes. After this period, the specimens were cleaned with 95% ethanol. The control group was composed by two specimens that did not receive any sealer or cleaning treatment. The sealer residues persistence after cleaning with 95% ethanol was evaluated by scanning electron microscopy (x500) and a score system was applied. Data obtained were analyzed by Kruskal-Wallis and Dunn tests (α = 5%). Results: Moderate amount of endodontic sealer residues were observed in all groups, regardless of the endodontic sealer compositions. G1, G2 and G3 presented similar amount of sealer residues on dentinal surface after cleaning with 95% ethanol (p > 0.05). Conclusion: 95% ethanol was inefficiency to remove completely AH Plus, Epiphany SE and Sealapex residues of sealer-contaminated dentin.

Ethanol is inneficient to remove endodontic sealer residues of dentinal surface

Introduction: Endodontic sealer residues on dentinal surface have negative effects on adhesion of adhesives system and/or can cause discoloration of the dental crown. Objective: To evaluate the efficacy of 95% ethanol in removal of residues of epoxy-based (AH Plus), methacrylate-based (Epiphany SE) or calcium-based (Sealapex) sealers on dentinal surface. Material and methods: Thirty-two bovine incisor dental crown fragments (0.5 mm x 0.5 mm) were treated with 17% EDTA and 2.5% NaOCl. The specimens were divided into three experimental groups (n = 10): G1 (AH Plus), G2 (Epiphany SE) and G3 (Sealapex). In each group was applied a coating of one endodontic sealer type and were left undisturbed for 5 minutes. After this period, the specimens were cleaned with 95% ethanol. The control group was composed by two specimens that did not receive any sealer or cleaning treatment. The sealer residues persistence after cleaning with 95% ethanol was evaluated by scanning electron microscopy (x500) and a score system was applied. Data obtained were analyzed by Kruskal-Wallis and Dunn tests (α = 5%). Results: Moderate amount of endodontic sealer residues were observed in all groups, regardless of the endodontic sealer compositions. G1, G2 and G3 presented similar amount of sealer residues on dentinal surface after cleaning with 95% ethanol (p > 0.05). Conclusion: 95% ethanol was inefficiency to remove completely AH Plus, Epiphany SE and Sealapex residues of sealercontaminated dentin.