Oral-Hygiene-Related Mobile Apps in the French App Stores: Assessment of Functionality and Quality.

Mobile health apps can contribute to increased quality of individual oral hygiene behaviors. This study provides an overview and an evaluation of quality of oral-hygiene-related mobile apps currently available in Google Play Store and the French Apple App. A shortlist of nine apps was assessed by 10 oral health professionals using the Mobile App Rating Scale. Intraclass correlation was used to evaluate interrater agreement. Best quality scores were obtained by Oral-B (3.4 ± 0.97), Colgate Connect (3.20 ± 0.63), and Preventeeth (3.10 ± 1.1) and worst ones by Mimizaur se brosse les dents (1.80 ± 0.79) and Kolibree (2.30 ± 0.82). The subjective quality scores ranged from 2.62 ± 0.61 (Oral-B) to 1.5 ± 0.61 (MSD). Specificity of the content ranged from 3.46 ± 0.84 (Preventeeth) to 1.78 ± 0.47 (Mimizaur se brosse les dents). Thus, even if oral health professionals positively evaluated the quality of oral-hygiene-related mobile apps, they are less assertive concerning their impact on the user's knowledge, attitudes, and intentions to change, as well as the likelihood of actual change in the oral hygiene behavior. Further investigations are needed to assess whether information from these apps is consistent with oral hygiene recommendations and to determine the long-term impacts of these apps.

Effect of Oral Prophylactic Measures on the Occurrence of Pre-Eclampsia (OP-PE) in High-Risk Pregnant Women: A Cluster Randomized Controlled Trial.

Pre-eclampsia (PE), a pregnancy-specific hypertensive disorder, characterized by the development of placental endothelial dysfunction, remains a major source of maternal and perinatal morbidity and mortality, especially in low- and middle-income settings. Periodontal disorders during pregnancy, and particularly periodontal pathogens, may be related to the risk of PE. Standard oral hygiene methods, based mainly on the joint use of toothbrushes and interdental brushes, reduce periodontal inflammatory risk and modulate the dysbiosis of the oral microbiome. The aim of this trial is to compare the PE outcomes in high-risk pregnant women receiving oral prophylactic measures to a control group. This trial is designed as a two-arm, parallel, cluster randomized controlled trial with the antenatal obstetric clinic as the unit of randomization and an allocation ratio of 1:1. The pregnant women will be included at 3 months of pregnancy and will be followed throughout the pregnancy. The primary outcome measure will be the incidence of PE from a baseline during the pregnancy. Secondary outcomes measures will include changes from the baseline in quantification of the pathogenic bacterial load of the interdental microbiota, the severity scores of periodontal indicators, and the incidence of adverse perinatal outcomes. This trial should demonstrate that the implementation of daily oral hygiene reduces oral dysbiosis, the incidence of periodontal disease, and the risk of PE.

Periodontal Conditions and Pathogens Associated with Pre-Eclampsia: A Scoping Review.

BACKGROUND: Pre-eclampsia, the second most frequent direct source of maternal mortality, is a multisystem gestational disorder characterized by proteinuria and maternal hypertension after the 20th gestational week. Although the causes of pre-eclampsia are still discussed, research has suggested that the placenta has a central place in the pathogenesis of this disease. Moreover, current surveys indicated that periodontal disorders observed during the pregnancy and more particularly, periodontal pathogens could be link to the risk of pre-eclampsia. OBJECTIVES: This article aims to review recent studies focusing on periodontal conditions and pathogens associated with pre-eclampsia. METHODS: The process followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines. RESULTS: Metabolic conditions, immunological changes, fluctuating progesterone and estrogen levels of the pregnant woman induce a dysbiosis of the oral microbiota and contribute to increase inflammation of periodontal tissues. Periodontal pathogens could diffuse through the bloodstream inducing a placenta inflammatory response as well as inflammatory molecules produced in response to periodontopathogens could migrate through the bloodstream leading to a placenta inflammatory response. Also, periodontopathogens can colonize the vaginal microbiota through the gastrointestinal tract or during oro-genital contacts. CONCLUSION: A cumulative bi-directional relationship between periodontal conditions, pathogens and the pre-eclampsia exists.

Salivary and Nasal Detection of the SARS-CoV-2 Virus After Antiviral Mouthrinses (BBCovid): A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: - To describe the evolution of the SARS-CoV-2 salivary viral load of patients infected with Covid-19, performing 7 days of tri-daily mouthwashes with and without antivirals. - To compare the evolution of the SARS-CoV-2 nasal and salivary viral load according to the presence or absence of antivirals in the mouthwash. TRIAL DESIGN: This is a multi-center, randomised controlled trial (RCT) with two parallel arms (1:1 ratio). PARTICIPANTS: Inclusion criteria - Age: 18-85 years old - Clinical diagnosis of Covid-19 infection - Clinical signs have been present for less than 8 days - Virological confirmation - Understanding and acceptance of the trial - Written agreement to participate in the trial Exclusion criteria - Pregnancy, breastfeeding, inability to comply with protocol, lack of written agreement - Patients using mouthwash on a regular basis (more than once a week) - Patient at risk of infectious endocarditis - Patients unable to answer questions - Uncooperative patient The clinical trial is being conducted with the collaboration of three French hospital centers: Hospital Center Emile Roux (Le Puy en Velay, France), Clinic of the Protestant Infirmary (Lyon, France) and Intercommunal Hospital Center (Mont de Marsan, France). INTERVENTION AND COMPARATOR: Eligible participants will be allocated to one of the two study groups. Intervention group: patients perform a tri-daily mouthwash with mouthwash containing antivirals (ß-cyclodextrin and Citrox®) for a period of 7 days. CONTROL GROUP: patients perform a tri-daily mouthwash with a placebo mouthwash for a period of 7 days. MAIN OUTCOMES: Primary Outcome Measures: Change from Baseline amount of SARS-CoV-2 in salivary samples at 4 and 9 hours, 1, 2, 3, 4, 5 and 6 days. Real-time PCR assays are performed to assess salivary SARS-CoV 2 viral load. SECONDARY OUTCOME MEASURES: Change from Baseline amount of SARS-CoV-2 virus in nasal samples at 6 days. Real-time PCR assays are performed to assess nasal SARS-CoV-2 viral load. RANDOMISATION: Participants meeting all eligibility requirements are allocated to one of the two study arms (mouthwash with ß-cyclodextrin and Citrox® or mouthwash without ß-cyclodextrin and Citrox®) in a 1:1 ratio using simple randomisation with computer generated random numbers. BLINDING (MASKING): Participants, doctors and nurses caring for participants, laboratory technicians and investigators assessing the outcomes will be blinded to group assignment. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): Both the intervention and control groups will be composed of 103 participants, so the study will include a total of 206 participants. TRIAL STATUS: The current protocol version is 6, August 4th, 2020. Recruitment began on April 6, 2020 and is anticipated to be complete by April 5, 2021. As of October 2, 2020, forty-two participants have been included. TRIAL REGISTRATION: This trial was registered on 20 April 2020 at www.clinicaltrials.gov with the number NCT04352959 . FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol." The study protocol has been reported in accordance with the Standard Protocol Items: Recommendations for Clinical Interventional Trials (SPIRIT) guidelines (Additional file 2)."

Nanoparticles as Anti-Microbial, Anti-Inflammatory, and Remineralizing Agents in Oral Care Cosmetics: A Review of the Current Situation.

Many investigations have pointed out widespread use of medical nanosystems in various domains of dentistry such as prevention, prognosis, care, tissue regeneration, and restoration. The progress of oral medicine nanosystems for individual prophylaxis is significant for ensuring bacterial symbiosis and high-quality oral health. Nanomaterials in oral cosmetics are used in toothpaste and other mouthwash to improve oral healthcare performance. These processes cover nanoparticles and nanoparticle-based materials, especially domains of application related to biofilm management in cariology and periodontology. Likewise, nanoparticles have been integrated in diverse cosmetic produces for the care of enamel remineralization and dental hypersensitivity. This review summarizes the indications and applications of several widely employed nanoparticles in oral cosmetics, and describes the potential clinical implementation of nanoparticles as anti-microbial, anti-inflammatory, and remineralizing agents in the prevention of dental caries, hypersensitivity, and periodontitis.

Microbiota of interdental space of adolescents according to Risk of Caries: A cross-sectional study protocol.

Dental caries is a major oral disease resulting from a complex interaction between the commensal microbiota, host susceptibility (heredity, immunity, diseases, etc.) and environmental factors (diet, dental hygiene, etc.). To predict the patient's risk of new carious lesions or progression of existing lesions, the Caries Risk Assessment (CRA) takes account of clinical, biological and behavioural factors. Thus, the CRA can predict whether the patient is at high or low risk of developing caries. The practitioner can thus set up a follow-up adapted to the risk of the patient. However, although bacteria are the main etiological factor of carious lesions, the CRA does not consider bacterial quantification or just focus on the level of S. mutans in the saliva. As the majority of cavities are interproximal in adolescence, the aim of this trial is to identify and quantify the interdental microbiota of adolescents aged from 15 to 17 years with low or high carious risk. So, the quantification of new biomarkers associated with carious lesion could be added to the CRA to improve it.

Calibrated interdental brushing for the prevention of periodontal pathogens infection in young adults - a randomized controlled clinical trial.

Periodontal disease is clearly correlated with systemic disease. The presence of periodontal pathogens in interdental spaces in young, healthy adults is a strong indicator of the need to introduce daily interdental prophylaxis. Twenty-five subjects (aged 18-35 years), diagnosticated clinically as periodontally healthy, were enrolled in this study. One hundred interdental sites were included. Among these sites, 50 "test" sites were cleaned daily with calibrated interdental brushes (IDBs), whereas the other 50 sites were not cleaned and considered "controls". The interdental biofilm at these interdental sites was collected at the beginning of the study (basal) and at 1 week, 2 weeks, 3 weeks, 4 weeks, and 3 months. Real-time polymerase chain reaction (PCR) methodology was used to quantify (i) 19 periodontal bacteria, including Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, and (ii) total bacteria. In the test sites, the quantity of total bacteria decreased over time with the use of IDBs. The bacteria from the red and orange Socransky complexes, which are associated with periodontal disease, significantly decreased in the test sites but not in the control sites. Bacteria from the yellow, and purple Socransky complexes, which are associated with periodontal health, increased significantly in both groups whereas bacteria from the blue Socransky complex increased significantly only in the test sites. Furthermore, at basal, 66% of test sites and 68% of control sites bled during interdental brushing. These percentages decreased by 85% in 3 months for the test sites and by 27% in the control sites. In conclusion, the daily use of calibrated IDBs can reduce periodontal pathogens, reestablish symbiotic microbiota and, decrease interdental inflammation in interdental sites of healthy young adults.

The Oral Bacterial Microbiome of Interdental Surfaces in Adolescents According to Carious Risk.

Adolescence is closely associated with a high risk of caries. The identification of specific bacteria in an oral microniche, the interdental space of the molars, according to carious risk can facilitate the prediction of future caries and the anticipation of the progression or stabilization of caries in adolescents. A cross-sectional clinical study according to the bacteriological criteria of interdental healthy adolescents and carious risk factors-low and high-using a real-time polymerase chain reaction technique was conducted. The presence of 26 oral pathogens from the interdental microbiota of 50 adolescents aged 15 to 17 years were qualitatively and quantitatively analyzed. Bacteria known to be cariogenic (Bifidobacterium dentium, Lactobacillus spp., Rothia dentocariosa, Streptococcus cristatus, Streptococcus mutans, Streptococcus salivarius, Streptococcus sobrinus, and Streptococcus wiggsiae) did not present differences in abundance according to carious risk. Periodontal bacteria from the red complex are positively correlated with carious risk. However, only 3 bacteria-S. sobrinus, E corrodens and T. forsythia-presented a significant increase in the highest group. Estimating the risk of caries associated with bacterial factors in interdental sites of molars in adolescents contributes to the better definition of carious risk status, periodicity and intensity of diagnostic, prevention and restorative services.

Effect of a Toothpaste/Mouthwash Containing Carica papaya Leaf Extract on Interdental Gingival Bleeding: A Randomized Controlled Trial.

Clinical research on herbal-based dentifrice +/- mouth rinse products is very limited compared with the plethora of research on conventional oral care products under normal oral hygiene conditions. The aim of this study was to determine the anti-inflammatory effects of a novel plant Carica papaya leaf extract (CPLE) on interdental bleeding in healthy subjects. In this randomized, single-blind parallel-design study, the eligible subjects were generally healthy non-smokers, aged 18⁻26, who exhibited healthy periodontal conditions upon study entry. The participants were equally randomized into the following four groups: CPLE dentifrice, CPLE dentifrice and mouthwash, sodium lauryl sulfate (SLS)-free enzyme-containing dentifrice and SLS-free enzyme-containing dentifrice with essential oil (EO) mouthwash. Subjects were instructed to brush their teeth twice a day without changing their other brushing habits. Interdental bleeding (BOIP) was measured from inclusion (T0) until the fourth week (T4) of the study. Clinical efficacy was assessed after one, two, three and four weeks of home use. The analyses compared BOIP between groups and were then restricted to participants with ≥70% and then ≥80% bleeding sites at T0. Pairwise comparisons between groups were performed at T0 and T4, and a logistic regression identified correlates of gingival bleeding (T4). Among 100 subjects (2273 interdental sites), the median percentage of bleeding sites per participant at T0 was 65%. The bleeding sites dramatically decreased in all groups between T0 and T4 (relative variations from -54% to -75%, p < 0.01 for all). Gingival bleeding did not significantly differ between the CPLE dentifrice and the SLS-free dentifrice +/- EO mouthwash groups (from p = 0.05 to p = 0.86), regardless of the baseline risk level. Among the CPLE dentifrice users, fewer bleeding sites were observed when toothpaste and mouthwash were combined compared to bleeding sites in those who used toothpaste alone (21% vs. 32%, p = 0.04). CPLE dentifrice/mouthwash provides an efficacious and natural alternative to SLS-free dentifrice +/-EO-containing mouthwash when used as an adjunct to mechanical oral care to reduce interdental gingival inflammation.

Educational outcomes of a new curriculum on interproximal oral prophylaxis for dental students.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of a preclinical oral prophylaxis education program by examining the effectiveness of the teaching module on changes to the students' attitudes towards their individual hygiene behaviors with interdental brushes (IDBs). METHODS: As being part of a new didactic program on oral interproximal prophylaxis, all preclinical third-year students (n = 96) enrolled in the 2014/15 academic year received theoretical, preclinical, and clinical lessons on interproximal prophylaxis. The evaluation of educational outcomes was linked to observed changes in students' hygiene behaviors using interdental brushes. Knowledge, skills, attitudes, satisfaction, competence and performance were also explored. The evaluation interviews were recorded at each recall, i.e., 1 week, 1 month, 3 months and 1 year after baseline. RESULTS: Motivation to use IDBs is clearly related to the perception of the effectiveness of the brushes and the perception of bleeding reduction. At one week, 89.6% of subjects reported using IDBs. Individual use decreased significantly from one week to one month (-26%, p = 0.006) while a non-significant upward trend occurred between one month and three months. Among students reporting usage of IDBs at 1 year (20.8%), only 2.0% used IDBs daily. Most students would recommend IDBs to other people at the beginning (69.8%). However, this share dropped to 50% at 3 months. IDB-users prescribed more than non-users. DISCUSSION AND PUBLIC HEALTH IMPLICATIONS: The implementation of a module on interdental hygiene practices in the oral health program is strongly recommended. However, corrective measures should be considered regarding the organization and frequency of recall periods in order to improve the performance of the curriculum.

Intraoral Scanner Technologies: A Review to Make a Successful Impression.

To overcome difficulties associated with conventional techniques, impressions with IOS (intraoral scanner) and CAD/CAM (computer-aided design and manufacturing) technologies were developed for dental practice. The last decade has seen an increasing number of optical IOS devices, and these are based on different technologies; the choice of which may impact on clinical use. To allow informed choice before purchasing or renewing an IOS, this article summarizes first the technologies currently used (light projection, distance object determination, and reconstruction). In the second section, the clinical considerations of each strategy such as handling, learning curve, powdering, scanning paths, tracking, and mesh quality are discussed. The last section is dedicated to the accuracy of files and of the intermaxillary relationship registered with IOS as the rendering of files in the graphical user interface is often misleading. This overview leads to the conclusion that the current IOS is adapted for a common practice, although differences exist between the technologies employed. An important aspect highlighted in this review is the reduction in the volume of hardware which has led to an increase in the importance of software-based technologies.

Efficacy of interdental calibrated brushes on bleeding reduction in adults: a 3-month randomized controlled clinical trial.

This study investigated the effect of interdental brushes on the reduction of interproximal bleeding in adults without periodontal disease. Forty-six adults were enrolled in a 3-month, observer-blinded, parallel-group randomized control trial. The test group used a standard manual toothbrush twice daily and an interdental brush daily. The control group used a standard manual toothbrush. At each visit, a calibrated colorimetric probe was used in all interdental spaces to determine the appropriate size of the interdental brush required, the brush of the corresponding size was introduced into the interproximal space, and the presence of bleeding was recorded. The outcome was the frequency of bleeding after application of the appropriate interdental brush. All participants were evaluated 1 wk, 1 month, and 3 months after the baseline visit. The overall preventive fraction with respect to bleeding frequency was 46% at 1 wk and 72% at 3 months. More bleeding reduction was observed in anterior sites than in posterior sites (80% vs. 69%, respectively). Participants with low baseline bleeding frequency presented with less bleeding (OR = 2.3). This study shows that daily use of calibrated interdental brushes reduces interdental bleeding. These findings may support interdental cleaning as an effective means to help individuals maintain and/or achieve optimal oral health.

Oral Health Behavior and Lifestyle Factors among Overweight and Non-Overweight Young Adults in Europe: A Cross-Sectional Questionnaire Study.

Being overweight is a risk factor for many chronic diseases including oral diseases. Our aim was to study the associations between oral health behavior, lifestyle factors and being overweight among young European adults, 2011-2012. The subjects constituted a representative sample of adult population aged 18-35 years from eight European countries participating in the Escarcel study. The participants completed a self-administered questionnaire on dietary habits, oral health behavior, smoking, exercise, height, and weight. Overweight was defined as body mass index (BMI) ≥ 25 kg/m² using the World Health Organization criteria. Mean BMI was 23.2 (SD 3.48) and 24.3% of the study population were overweight. Those who were overweight drank more soft drinks (p = 0.005) and energy drinks (p = 0.006) compared with those who were non-overweight. Brushing once a day (OR 1.6; 95% CI 1.3-2.0), emergency treatment as the reason for last dental visit (OR 1.6; 95% CI 1.3-1.9) and having seven or more eating or drinking occasions daily (OR 1.4; 95% CI 1.1-1.7) were statistically significantly associated with overweight. Associations were found between oral health behavior, lifestyle and overweight. A greater awareness of the detrimental lifestyle factors including inadequate oral health habits among overweight young adults is important for all healthcare providers, including oral health care professionals.

Quantitative Molecular Detection of 19 Major Pathogens in the Interdental Biofilm of Periodontally Healthy Young Adults.

In oral health, the interdental spaces are a real ecological niche for which the body has few or no alternative defenses and where the traditional daily methods for control by disrupting biofilm are not adequate. The interdental spaces are the source of many hypotheses regarding their potential associations with and/or causes of cardiovascular disease, diabetes, chronic kidney disease, degenerative disease, and depression. This PCR study is the first to describe the interdental microbiota in healthy adults aged 18-35 years-old with reference to the Socransky complexes. The complexes tended to reflect microbial succession events in developing dental biofilms. Early colonizers included members of the yellow, green, and purple complexes. The orange complex bacteria generally appear after the early colonizers and include many putative periodontal pathogens, such as Fusobacterium nucleatum. The red complex (Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) was considered the climax community and is on the list of putative periodontal pathogens. The 19 major periodontal pathogens tested were expressed at various levels. F. nucleatum was the most abundant species, and the least abundant were Actinomyces viscosus, P. gingivalis, and Aggregatibacter actinomycetemcomitans. The genome counts for Eikenella corrodens, Campylobacter concisus, Campylobacter rectus, T. denticola, and Tannerella forsythensis increased significantly with subject age. The study highlights the observation that bacteria from the yellow complex (Streptococcus spp., S. mitis), the green complex (E. corrodens, Campylobacter gracilis, Capnocytophaga ochracea, Capnocytophaga sputigena, A. actinomycetemcomitans), the purple complex (Veillonella parvula, Actinomyces odontolyticus) and the blue complex (A. viscosus) are correlated. Concerning the orange complex, F. nucleatum is the most abundant species in interdental biofilm. The red complex, which is recognized as the most important pathogen in adult periodontal disease, represents 8.08% of the 19 bacteria analyzed. P. gingivalis was detected in 19% of healthy subjects and represents 0.02% of the interdental biofilm. T. forsythensis and T. denticola (0.02 and 0.04% of the interdental biofilm) were detected in 93 and 49% of healthy subjects, respectively. The effective presence of periodontal pathogens is a strong indicator of the need to develop new methods for disrupting interdental biofilm in daily oral hygiene.

Access to Interdental Brushing in Periodontal Healthy Young Adults: A Cross-Sectional Study.

PURPOSE: Interdental diameter space is largely undefined in adults, which compromises the decision support for daily interdental cleaning during routine practice in individual oral prophylaxis. This study assesses the distribution of diameter access of interdental spaces in an 18- to 25-year-old adult population free of periodontal disease. METHODS: In March-April 2015, a cross-sectional study using random sampling was performed at the University Lyon 1, France. The interproximal dental spaces of 99 individuals were examined using a colorimetric calibrated probe associated with the corresponding calibrated interdental brush (IDB). RESULTS: Of the 2,408 out of 2,608 sites, the overall accessibility prevalence of any interdental brushing was 92.3%. In total, 80.6% of the sites required interdental brushes with smaller diameters (0.6-0.7 mm). In anterior sites, the diameter of the interdental brushes used was smaller (55.8% of IDB with 0.6 mm) than the diameter of the interdental brushes used in posterior sites (26.1% of IDB with 0.6 mm) (p < 0.01). The adjusted ORs indicate a significant association with the location of the sites (approximately doubling the risk of bleeding, i.e., OR = 1.9, in posterior sites). CONCLUSIONS: Most interdental sites can be cleaned using interdental brushes. Even in healthy people, interdental hygiene requirements are very high. Strengthening the oral hygiene capacity by specifically using interdental brushes can have an effect on the health of the entire population. Screening of the accessibility of the interdental space should be a component of a routine examination for all patients.

Corrosion resistance measurements of dental alloys, are they correlated?

OBJECTIVES: The aim was to assess in vitro the resistance to corrosion of eight commercial dental alloys by two quantitative methods, electrochemical and immersion tests, then to statistically test the hypothesis of possible correlation between the polarization resistance (R(p)) and the elemental release. METHODS: Two quantitative methods; electrochemical and immersion test, were used. From the first, after recording the OCP during 24h immersion in acidified artificial saliva (pH 2.3), R(p) was obtained using the linear polarization in anodic path and applying the Mansfeld's method. From the static immersion test, using the same test solution, the elemental release from was analysed and determined using the ICP-AES. Thereafter, the two measurements were used to plot the regression line and to determine the correlation coefficient. The significance of the correlation was tested using F-test at a confidence interval of 0.99. RESULTS: : The resistance to corrosion results obtained from the two methods were ranked and compared; an inverse relation between them was evident. Then, the obtained coefficient of correlation (R(2)) was 0.886. With the F-test at 0.99 confidence interval, the hypothesis was accepted as the calculated F was about 44 against critical F=13.7. CONCLUSION: The correlation between the two measurements, R(p) and mass loss, was proved statistically significant. This result may provide a new approach to predict the corrosion behaviour of dental alloys by firstly using the easier methods.

Combination fixed and removable prostheses using a CoCr alloy: a clinical report.

It is now possible to provide combination fixed/removable prosthetic restorations using only 1 dental alloy, such as CoCr, a nonprecious alloy. This alloy offers clinical performance and demonstrated corrosion resistance. This clinical report demonstrates use of a single CoCr alloy for metal-ceramic fixed partial dentures in conjunction with a mandibular removable partial denture.

Influence of casting procedures on the corrosion resistance of clinical dental alloys containing palladium.

The aim of this study was to compare the in vitro corrosion resistance in artificial saliva of two palladium-silver alloys (a Pd-Ag (Pors on 4) and an Ag-Pd (Palliag LTG)), with and without casting defects; 1 nickel-chrome alloy and 1 high-gold alloy, cast under recommended conditions, served as controls. For each of the palladium-based alloys, three specimens corresponding to three different casting conditions were used: under recommended conditions, with the use of a graphite-containing investment and crucible, and by reusing the sprues and sprue button. The electrochemical tests were run in Fusayama-Meyer artificial saliva. The open-circuit potential was recorded in mV/SCE at t=24h. Then, potentiodynamic polarization was performed to measure the polarization resistance (R(p)) in kOmega cm(2) and the corrosion current (i(corr)) in microA cm(-2). Data were evaluated with one-way analysis of variance and multiple comparisons test (alpha=0.05). In addition, each specimen was examined by scanning electron microscopy. Compared to the control alloys, the electrochemical experiments in artificial saliva indicated satisfactory corrosion resistance for the Pd-Ag and Ag-Pd alloys; these results are related to their high noble metal content and stable substructure. The Pd-Ag alloy displayed superior electrochemical properties to those of the Ag-Pd alloy regardless of the casting condition. The use of the graphite-containing crucible and investment during the cast process did not dramatically reduce the corrosion resistance values, but the reuse of sprues and the sprue button did. The optimal corrosion resistance values were obtained for the alloys cast according to the recommended conditions.

Corrosion resistance of cobalt-chromium and palladium-silver alloys used in fixed prosthetic restorations.

The corrosion resistance of a cobalt-chromium (Co-Cr) alloy was assessed with a view to determining its potential use in the manufacture of fixed dental prostheses. The electrochemical behaviour of the alloy was compared with that of two palladium (Pd)-based alloys. Measurements of corrosion potential and anodic polarization were performed on the alloys, and the specimen surfaces were examined by using scanning electron microscopy. Although the corrosion potential of the Co-Cr alloy was lower than that of the Pd-based alloys, the corrosion currents and polarization resistance values were similar for all three alloys. All materials showed a very high resistance to corrosion. Given that the beneficial mechanical properties of Co-Cr alloys have already been established, this type of alloy may be a suitable alternative for use in the manufacture of fixed dental prostheses.