Esthetic alternative for fluorosis blemishes with the usage of a dual bleaching system based on hydrogen peroxide at 35%

Esthetic dental procedures in pediatric dentistry represent sources of satisfaction and realization, as much for the patient as for the professional. Lack of dental esthetics may develop psychological problems in infant as well as in adolescent patients. Blemishes produced by fluorosis appear as a challenge to the pediatric dentist and alternatives for treatment are desired. The scope of this present paper is to relate a clinical case with esthetic solution for blemishes in teeth enamel due to fluorosis. A dual system of bleaching was used (photo/chemically activated) based on hydrogen peroxide at 35% (Hi-Lite-Shofu) in a male eight-year-old patient with white fluorosis blemishes on teeth 11 and 21. The bleaching system used was efficient in bleaching teeth with white blemishes due to fluorosis, thus masking the blemishes and providing a more uniform appearance.     

Human enamel veneer restoration in a deciduous tooth: clinical case

Trauma to deciduous anterior teeth, frequently occur in children, and the treatment is a big challenge for the pediatric dentistry. In these cases, besides the pain and discomfort provoked by the injury, both child and parents/persons responsible were eager to reconstruct the damage, as soon as possible. In modern operative restorative dentistry, no restorative material is able to substitute for the human dental enamel in quality, color and resistance. The aim of this paper is to relate the treatment of esthetic veneer (facet) of human dental enamel in a three-year-old child after trauma that caused concussion and accentuated color alteration. Clinical results showed an efficient esthetical resolution, revealing it to be a good alternative for treatment of traumatized anterior deciduous teeth.     

SHEAR BOND STRENGTH OF ORTHODONTIC BRACKETS TO ENAMEL UNDER DIFFERENT SURFACE TREATMENT CONDITIONS

The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI) of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15). In Groups 1 (control) and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturer''s recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-μm aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37°C for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa) showed no statistically significant difference between Groups 4 and 6 (p>0.05). Likewise, no statistically significant differences (p>0.05) were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (p<0.05). Group 3 had statistically significant lower bond strength than Groups 2, 4, and 6, but no statistically significant differences were found on comparison to Groups 1 and 5. A larger number of fractures at the bracket/composite interface were evidenced by the ARI scores. OrthoPrimer bonding agent yielded higher bond strength in the groups using either conventional or sandblasted polycarbonate brackets, which was not observed in the groups using metallic brackets.     

Screw vs cement-implant-retained restorations: an experimental study in the beagle. Part 2. Immunohistochemical evaluation of the peri-implant tissues

Crestal bone loss has been reported to occur around dental implants. Even if the causes of this bone loss are not completely understood, the presence of a microgap between implant and abutment with a possible contamination of the internal portion of the implants has been suggested. The aim of this study was to see if there were differences in the vascular endothelial growth factor (VEGF) expression, microvessel density (MVD), proliferative activity (MIB-1), and inflammatory infiltrate in the soft tissues around implants with screwed and cemented abutments. Sandblasted and acid-etched implants were inserted in the mandibles of 6 Beagle dogs. Ten 3.5- x 10-mm root-form implants were inserted in each mandible. A total of 60 implants (30 with screwed abutments and 30 with cemented abutments) were used. After 12 months, all the bridges were removed and all abutments were checked for mobility. A total of 8 loosened screws (27%) were found in the screwed abutments, whereas no loosening was observed in cemented abutments. A gingival biopsy was performed in 8 implants with cemented abutments, in 8 implants with screwed abutments, and in 8 implants with unscrewed abutments. No statistically significant differences were found in the inflammatory infiltrate and in the MIB-1 among the different groups. No statistically significant difference was found in the MVD between screwed and cemented abutments (P = .2111), whereas there was a statistically significant difference in MVD between screwed and unscrewed abutments (P = .0277) and between cemented and unscrewed abutments (P = .0431). A low intensity of VEGF was prevalent in screwed and in cemented abutments, whereas a high intensity of VEGF was prevalent in unscrewed abutments. These facts could be explained by the effects induced, in the abutments that underwent a screw loosening, by the presence of bacteria inside the hollow portion of the implants or by enhanced reparative processes.     

Effect of mechanical cycling on the flexural strength of densely sintered ceramics.

OBJECTIVES: The aim of this study was to evaluate the effect of mechanical cycling on the biaxial flexural strength of two densely sintered ceramic materials. METHODS: Disc shaped zirconia (In-Ceram Zirconia) and high alumina (Procera AllCeram) ceramic specimens (diameter: 15 mm and thickness: 1.2 mm) were fabricated according to the manufacturers' instructions. The specimens from each ceramic material (N=40, n=10/per group) were tested for flexural strength either with or without being subjected to mechanical cycling (20,000 cycles under 50 N load, immersion in distilled water at 37 degrees C) in a universal testing machine (1 mm/min). Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha=0.05). RESULTS: High alumina ceramic specimens revealed significantly higher flexural strength values without and with mechanical cycling (647+/-48 and 630+/-43 MPa, respectively) than those of zirconia ceramic (497+/-35 and 458+/-53 MPa, respectively) (p<0.05). Mechanical cycling for 20,000 times under 50 N decreased the flexural strength values for both high alumina and zirconia ceramic but it was not statistically significant (p>0.05). SIGNIFICANCE: High alumina ceramic revealed significantly higher mean flexural strength values than that of zirconia ceramic tested in this study either with or without mechanical cycling conditions.     

Effect of surface treatment of a glass-infiltrated alumina ceramic on the microtensile bond strength

This study evaluated the microtensile bond strength of a resin composite to a ceramic submitted to three surface treatments. Twelve glass-infiltrated alumina ceramic blocks (In-Ceram Alumina, VITA) and twelve resin composite blocks (Clearfil APX, Kuraray) with dimensions of 6mm x 6mm x 5mm were made. The surface of the ceramic was wet-grounded with # 600, 800 and 1200-grid sandpaper, and the blocks were divided in three groups: Group 1 - sandblasting with aluminum oxide - particles 110mm (Micro-Etcher, Danville); Group 2 - Rocatec System (ESPE): Tribochemical silica coating (Rocatec pre-powder + Rocatec-Plus powder + Rocatec-Sil); Group 3 - CoJet System (3M/ESPE): silica coating (silica oxide + ESPE-Sil). The ceramic blocks were cemented to the resin composite blocks with Panavia F (Kuraray Co), following the manufacturer's instructions, under load of 750g for 10min. The samples were stored (distilled water / 7 days / 37O C) and sectioned in two axis, x and y, with diamond disk under cooling in order to obtain samples (S) with 0.6 ± 0.1mm2 of adhesive area (n=36). The S were attached in adapted device for the microtensile test that was performed at an universal testing machine (EMIC), at a speed of 1mm/min. The results (MPa) were submitted to ANOVA and Tukey's test (p<0.05): G1 - 15.36; G2 - 30.98; G3 - 31.25. Groups 2 (Rocatec) and 3 (CoJet) presented larger bond strength than group 1. There was no statistical difference between group 2 and group 3.     

Clinical evaluation of three different materials used as pit and fissure sealant: 24-months results

To evaluate the retention and caries experience effects of three different materials used as fissure sealants after 24 months of clinical application: a resin-modified glass ionomer cement (A), a flowable resin composite (B) and a compomer (C). One hundred and seventeen (117) teeth were sealed with material A, 119 teeth with material B and 120 teeth with material C. Children were randomly assigned. Each one received only one of the materials studied. Plaque index, dmft score and socioeconomic level were scored at baseline. The clinical exams were conducted 6, 12 and 24 months after application of the sealant. Statistical analysis (Kruskal-Wallis) revealed that there were statistically significant differences between the retention rates of groups A and B and between groups B and C after 2 years, with material B showing better results. After 2 years, 3.1% of the teeth of group A, 4.3% of group B and 6.7% of group C were Carious+Filled. There was no evidence of association between caries presence after 2 years and plaque index, dmft score and socioeconomic level. These results suggest that flowable resin composite had a satisfactory retention after this period of evaluation and all three materials were effective on occlusal caries prevention.     

Capacity of coronal dentin to increase fiberglass post retention: a pull-out test

PURPOSE: To evaluate the capacity of residual dentin in the coronal part of the root canal to increase the retention of serrated fiberglass posts (Extra-glass P-6%). METHODS: 40 freshly-extracted maxillary central incisors were randomly and evenly divided into four test groups (TGs) with no (TG0), one (TG1), two (TG2) and three (TG3) coronal walls, respectively. After shaping, the canals were filled with gutta-percha and prepared to receive fiberglass posts. Coronal wall dentin was etched with 38% phosphoric acid for 60 seconds, rinsed, and dried. Dentin bonding agent (Prime & Bond NT) was applied, and fiberglass posts were luted for 8 mm into the post space using a self-cure composite (ResiLute). All samples were then subjected to tensile forces in a universal testing machine. Data were analyzed with ANOVA and Student t-tests (P< 0.01). RESULTS: The samples with residual coronal dentin showed higher bond strength than the samples without residual crown walls (TG0=100.30N; TG1=201.83N; TG2=263.54N; TG3=278.86N). The differences between the groups were all statistically significant at P< 0.01, except for the difference in tensile strength between TG2 and TG3, which was not statistically significant. Residual crown walls significantly increased the tensile load required to displace the posts.