Fracture resistance of teeth submitted to several internal bleaching protocols

Aim: The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP). Materials and methods: After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%). Results: The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p < 0.05). Conclusion: All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other. Clinical significance: There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.

Influence of standard load micro and nanopatterned in surface roughness of bleached teeth and submitted to different surface treatments?

The aim of this study was evaluate the dental enamel after whitening treatment with Opalescence Boost PF® 38%, correlating the structural alterations in the surface of the enamel with its respective pH and verify if whitened teeth submitted to different finishing and polishing techniques show similar surface texture to healthy teeth (control group). Sixty premolars were divided in 6 groups (n = 10), which had been immersed in artificial saliva during all the experiment. Protocol whitening was performed according to the manufacturer recommendations, and then the specimens were submitted to different polishing technique with Sof-Lex Pop On® disks, Flex Diamond® felt disks using two different micrometric polishing pastes (Enamelize® and Diamond Polish®) and two nanometric polishing pastes (Lummina-E Diamond and Lummina-E Alumina), according to the groups. Representative specimens were analyzed in scanning electronic microscopy (SEM). Whitening gel used in this experiment had modified the morphologic aspect of the enamel surface. It was found that two nanometric polishing pastes (G5 and G6) promoted a less rough surface compared to control group even after the whitening process.

Can an LED-laser hybrid light help to decrease hydrogen peroxide concentration while maintaining effectiveness in teeth bleaching?

The aim of this study was to compare the bleaching efficacy of 35% hydrogen peroxide and 15% hydrogen peroxide with nitrogen-doped titanium dioxide catalysed by an LED-laser hybrid light. We studied 70 patients randomized to two groups. Tooth shade and pulpal sensitivity were registered. Group 1: 15% hydrogen peroxide with nitrogen-doped titanium dioxide. Group 2: 35% hydrogen peroxide. Both groups were activated by an LED-laser light. No significant differences were seen in shade change immediately, one week or one month after treatment (p > 0.05). Differences were seen in pulpal sensitivity (p < 0.05). The use of an LED-laser hybrid light to activate 15% hydrogen peroxide gel with N_TiO2 permits decreasing the peroxide concentration with similar aesthetic results and less pulpal sensitivity than using 35% hydrogen peroxide for bleaching teeth.

Colour stability of acrylic resin denture teeth after immersion in different beverages

The colour stability of acrylic resin denture teeth in beverages was investigated. A spectrophotometer measured the colour (CIE-L*a*b* system) of all specimens after storage in distilled water for 24 h at 37°C (T0). Specimens were then immersed in various beverages. After 15 days (T1) and 30 days (T2), for each material, the mean ∆E values were calculated and compared by two-way ANOVA and Tukey intervals (α=0.05). In the ∆T0T1 period, specimens stored in red wine were significantly discoloured, compared to distilled water (P=0.003). There was no difference between immersion solutions in ∆ET0T2 (P=0.772) and in ∆ET1T2 (P=0.058), and no difference between materials in all immersion periods.

Effect of thermal and mechanical cycles on the hardness and roughness of artificial teeth

In this study the effects of thermal and mechanical cycles on the hardness and roughness of artificial teeth were evaluated. Materials and Methods:Specimens were prepared and stored in distilled water at 37ºC for 48 hours (n=10).The hardness and roughness readings were made in the following time intervals, according to each group:G1: after specimen storage in distilled water at 37°C for 48 hours; G2: after 600.000 constant mechanical cycles; G3: after 1.200.000 constant mechanical cycles; G4: after 2.500 thermalcycling baths, alternated between hot water (55°C) and cold water (5°C) and G5: after 5.000 thermalcycling baths, alternated between hot water (55°C) and cold water (5°C). After cycling and storage procedures, the specimens of each group were submittedto surface roughness and hardness readouts. Statistical evaluation was performed by three-way analysis of variance, complemented by the Tukey multiple comparisons of means test. The level of significance adopted was 5%. There was no significant difference between G1, G4 and G5 as regards mean roughness of different brands of artificial teeth. Groups G2 and G3 showed higher mean roughness values, and generally equivalent values in all time intervals, except for Trilux (G3> G2). Significant differences in hardness values were observed in different brands of artificial teeth, and differences in values after thermal and mechanical cycling. In conclusion, our findings suggest that thermal cyclingdid not change the roughness of the artificial teeth tested, but after the mechanical cycling the roughness values increased. Thermal and mechanical cycling influenced the hardness of the artificial teeth tested.

Fracture resistance of endodontically-treated teeth submitted to bleaching treatment with hydrogen peroxide and titanium dioxide nanoparticles photoactivated by LED-laser

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Molar incisor hypomineralization (MIH): conservative treatment management to restore affected teeth

The purpose of this study was to evaluate the 12-month clinical performance of glass ionomer restorations in teeth with MIH. First permanent molars affected by MIH (48) were restored with glass ionomer cement (GIC) and evaluated at baseline, at 6 and at 12 months, by assessing tooth enamel breakdown, GIC breakdown and caries lesion associations. The data were analyzed using the chi-square test and actuarial survival analysis. The likelihood of a restored tooth remaining unchanged at the end of 12 months was 78%. No statistically significant difference was observed in the association between increased MIH severity and caries at baseline (p > 0.05) for a 6-month period, or between increased MIH severity and previous unsatisfactory treatment at baseline (p > 0.05) for both a 6- and 12-month period. A statistically significant difference was observed in the association between increased MIH severity and extension of the restoration, involving 2 or more surfaces (p < 0.05) at both periods, and between increased MIH severity and caries at baseline (p < 0.05) at a 12-month period. Because the likelihood of maintaining the tooth structures with GIC restorations is high, invasive treatment should be postponed until the child is sufficiently mature to cooperate with the treatment, mainly of teeth affected on just one face.

Fracture resistance of simulated immature teeth after different intra-radicular treatments

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Taste alteration, mouth dryness and teeth staining as side effects of medications taken by elderly

Elderly patients generally use several types of medication, some of which may cause oral side effects. Aim: To investigate the oral side effects caused by medication in an elderly sample. Methods: Three hundred patients were interviewed about their use of medication and were divided in two groups: institutionalized (n=150) and community-dwelling (n=150) elderly. Results: The most used drugs were antihypertensives (53%) for community-dwelling elders and antiulceratives (76%) for the institutionalized ones. The more prevalent side effects were taste alterations that occurred in 19%, dry mouth in 17% and teeth staining in 2%. Conclusions: A high prevalence of oral side effects from medications used by the elderly was found in this study. The health professionals should be aware of the possible side effects caused by prescribed medications.

Assessment of structural cardiac abnormalities and diastolic function in women with gestational diabetes mellitus

Background: The main manifestation of hyperglycaemia during pregnancy is gestational diabetes mellitus. It can herald diabetes mellitus type 2 and its deleterious long-term effects, such as hypertension and cardiovascular disease. The aim of this study was to assess diastolic function in women with gestational diabetes mellitus, one of the first signs of future cardiovascular disease.Methods: A total of 21 women with gestational diabetes mellitus and 23 healthy pregnant women (control group) between 34 and 37weeks of gestation underwent echocardiographic assessment. The diagnosis of gestational diabetes mellitus was made in agreement with the American Diabetes Association criteria. Echocardiographic images obtained were analysed according to the criteria of the American Society of Echocardiography. Data were analysed using Pearson correlation coefficient, analysis of variance and Student's t-test.Results: Women with gestational diabetes mellitus had higher posterior wall and interventricular septum thickness, increased left ventricular mass and left ventricular mass index, lower early diastolic annular velocity and early diastolic annular velocity/late diastolic annular velocity ratio. There was a positive correlation between left ventricular mass index and fasting glucose and pregnancy body mass index.Conclusion: Patients with gestational diabetes mellitus seem to have a different diastolic profile as well as a mildly dysfunctional pattern on echocardiogram, which may show a need for greater glycaemic control.

Long-term clinical evaluation of the color stability and stainability of acrylic resin denture teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stress distribution in delayed replanted teeth splinted with different orthodontic wires: a three-dimensional finite element analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of method of caries induction on aged resin-dentin bond of primary teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Responses of Dental Pulp Cells to a Less Invasive Bleaching Technique Applied to Adhesively Restored Teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)