Influence of storage times on bond strength of resin cements to root canal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reestablishment of occlusion with prosthesis and composite resin restorations

Here, we present a case report on prosthetic reconstruction of posterior teeth and composite resin restoration of anterior teeth yielding considerable esthetic improvement, reestablishment of disocclusion guides and function.

Root canal filling: fracture strength of fiber-reinforced composite-restored roots and finite element analysis

The aims of this study were to evaluate the effect of root canal filling techniques on root fracture resistance and to analyze, by finite element analysis (FEA), the expansion of the endodontic sealer in two different root canal techniques. Thirty single-rooted human teeth were instrumented with rotary files to a standardized working length of 14 mm. The specimens were embedded in acrylic resin using plastic cylinders as molds, and allocated into 3 groups (n=10): G(lateral) - lateral condensation; G(single-cone) - single cone; G(tagger) - Tagger's hybrid technique. The root canals were prepared to a length of 11 mm with the #3 preparation bur of a tapered glass fiber-reinforced composite post system. All roots received glass fiber posts, which were adhesively cemented and a composite resin core was built. All groups were subjected to a fracture strength test (1 mm/min, 45°). Data were analyzed statistically by one-way ANOVA with a significance level of 5%. FEA was performed using two models: one simulated lateral condensation and Tagger's hybrid technique, and the other one simulated the single-cone technique. The second model was designed with an amount of gutta-percha two times smaller and a sealer layer two times thicker than the first model. The results were analyzed using von Mises stress criteria. One-way ANOVA indicated that the root canal filling technique affected the fracture strength (p=0.004). The G(lateral) and G(tagger) produced similar fracture strength values, while G(single-cone) showed the lowest values. The FEA showed that the single-cone model generated higher stress in the root canal walls. Sealer thickness seems to influence the fracture strength of restored endodontically treated teeth.

Influence of dental chair backrest inclination on the registration of the mandibular position

Varying the inclination of the dental chair backrest might alter the distribution of occlusal contact points. The purpose of this study was to identify the influence of backrest inclination on the registration of the mandibular position. Ten participants aged between 18 and 30 years with a complete permanent dentition, uncompromised motor function, no tooth mobility, and no temporomandibular disorders were selected. To register interocclusal contacts, an autopolymerizing methylmethacrylate device was adapted to the maxillary anterior teeth and a composite resin increment was added to the mandibular central incisors. Contacts were registered with the following variations in the inclination of the dental chair backrest: 90 degrees, 120 degrees, and 180 degrees. A standardized digital photograph was made of each mark in each backrest position, and the images were superimposed to measure the distances in registration from 90 to 120 and from 90 to 180 degrees. Data were analyzed with the Student paired t test (α=.05). When the chair was inclined from the 90-degree to the 120-degree position, the mandible was repositioned posteriorly by a mean of 0.67 mm, but the difference was not statistically significant. When the chair was inclined from the 90-degree to the 180-degree position, however, the mandible was repositioned posteriorly by a statistically significant mean of 1.41 mm. Mandibular position is influenced by increasing inclination, and this influence was statistically significant at a 180-degree incline.

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Abutment coating with diamond-like-carbon films to reduce implant-abutment bacterial leakage

Backgroud: The influence of diamond-like-carbon (DLC) films on bacterial leakage through the interface between abutments and dental implants of external hexagon (EH) and internal hexagon (IH) was evaluated. Film deposition was performed by PECVD (Plasma Enhanced Chemical Vapor Deposition). Sets of implants and abutments (N=180, n=30) were divided according to the connection design and the treatment of the abutment base: (1) no treatment (control); (2) DLC film deposition, and (3) Ag-DLC film deposition. Under sterile conditions, 1 µL of Enterococcus faecalis was inoculated inside the implants, and abutments were tightened. The sets were tested for immediate external contamination, suspended in test tubes containing sterile culture broth, and followed-up for five days. Turbidity of the broth indicated bacterial leakage. At the end of the period, the abutments were removed and the internal content of the implants was collected with paper points and plated in Petri dishes. They were incubated for 24 h for bacterial viability assessment and colony-forming unit (CFU) counting. Bacterial leakage was analyzed by Chi-square and Fisher exact tests (α=5%). The percentage of bacterial leakage was 16.09% for EH implants and 80.71% for IH implants (P<0.0001). The bacterial load was higher inside these implants (P=0.000). The type of implant significantly influenced the results (P=0.000), whereas the films did not (P=0.487). We concluded that: (1) IH implants showed a higher frequency of bacterial leakage and (2) the DLC and Ag-DLC films did not significantly reduce the frequency of bacterial leakage and bacteria load inside the implants.

Resistência ao cisalhamento de diferentes sistemas adesivos no esmalte dental

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Treatment of traumatic dental intrusion by surgical repositioning: clinical case report

The prevalence of dental trauma and its consequences are challenging. This article presents a clinical case of a 9-year-old female who was in a bicycling accident and had a dental intrusion of the left maxillary lateral incisor with extensive dislocation. In the emergency department, surgical repositioning of the intruded tooth and a splinting with steel wire and composite resin was performed and the soft-tissue lesions were sutured. Two weeks after the first visit, pulp necrosis was found and endodontic treatment of the intruded tooth was started with a calcium hydroxide dressing. Despite the traumatic nature of the dental injury, the result of treatment was favorable. After 3 years of follow-up, repair of the resorptions and no signs of ankylosis of the teeth involved were evident. Considering the patient's age and the extent of intrusion, it was concluded that surgical repositioning associated with adequate endodontic therapy was an effective alternative treatment for this case.

Composite resin susceptibility to red wine staining after water sorption

Color stability of restorative materials is essential for longevity of esthetic composite restoration over time. The aim of this investigation was assess the effect of prior water immersion on the color stability of a composite resin to red wine staining. Seventy disccshaped specimens (6mm x 1.5mm) were carried out and randomized in 7 groups (n = 10), according to distilled water immersion time at 0 (control), 24, 48, 72,120,192, and 240 h. Baseline color was measured according to the ciel*a*b* system using a reflection spectrophotometer(uvc2450, shimadzu).After that, the specimens were storage in red wine for 7 days. Color difference (∆e) after aging was calculated based on the color coordinates before(baseline) and after storage period.Data were subjected to onecway anova(alpha=0.05).The different times of immersion in.Water before to the red wine storage showed similar behavior on the color stability, without statistical difference compared to control group, immersed directly in the wine(p=0.7057).The previous water uptake of composite resin evaluated did not decrease the susceptibility to red wine staining.

Evaluation in situ of tag formation in dental enamel submitted to microabrasion technique: effect of two etching times

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação in vitro do tempo de fotopolimerização com led de alta potência de bráquetes ortodônticos e remoção de adesivo remanescente sob luz ultravioleta

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Leakage of Saliva Through the Implant-Abutment Interface: In Vitro Evaluation of Three Different Implant Connections Under Unloaded and Loaded Conditions

Purpose: Bacterial leakage along the implant-abutment interface, with consequent species harboring the inner parts of two-part dental implant systems, has been reported in the literature. The aim of this in vitro study was to evaluate bacterial leakage from human saliva to the internal part of the implants along the implant-abutment interface under loaded and unloaded conditions using DNA Checkerboard. Materials and Methods: Sixty denial implants-20 each of external-hexagon, internal-hexagon, and Morse cone-connection designs-and their conical abutments were used in this study. Each group was subdivided into two groups of 10 loaded and 10 unloaded implants. The assemblies were immersed in human saliva and either (1) loaded with 500,000 cycles at 120 N (experimental group) or (2) incubated in static conditions for 7 days at 35 degrees C (unloaded control group). Results: Microorganisms were found in the internal surfaces of all types of connections. The Morse cone connection presented the lowest count of microorganisms in both the unloaded and loaded groups. Loaded implants presented with higher counts of microorganisms than unloaded implants for external- and internal-hex connections. Conclusion: Bacterial species from human saliva may penetrate along the implant-abutment interface under both unloaded and loaded conditions for all connections evaluated. Morse cone-connection implants showed the lowest counts of microorganisms for both conditions. External- and internal-hex implants showed a higher incidence of bacteria and higher bacterial counts after simulated loading. INT J ORAL MAXILLOFAC IMPLANTS 2012;27:551-560.

Relationship between elastic and mechanical properties of dental ceramics and their index of brittleness

The purpose of the study was to verify the effects of a number of materials' parameters (crystalline content; Young's modulus, E; biaxial flexure strength, sigma(i); Vickers hardness, VH; fracture toughness, K-Ic; fracture surface energy, gamma(f); and index of brittleness, B) on the brittleness of dental ceramics. Five commercial dental ceramics with different contents of glass phase and crystalline particles were studied: a vitreous porcelain (VM7/V), a porcelain with 16 vol% leucite particles (d.Sign/D), a glass-ceramic with 29 vol% leucite particles (Empress/E1), a glass-ceramic with 58 vol% lithium-disilicate needle-like particles (Empress 2/E2), and a glass-infiltrated alumina composite with 65 vol% crystals (In-Ceram Alumina/IC). Discs were constructed according to manufacturers' instructions, ground and polished to final dimensions (12 mm x 1.1 mm). Elastic constants were determined by ultrasonic pulse-echo method. sigma(i) was determined by piston-on-3-balls method in inert condition. VH was determined using 19.6 N load and K-Ic was determined by indentation strength method. gamma(f) was calculated from the Griffith-Irwin relation and B by the ratio of HV to K-Ic. IC and E2 showed higher values of sigma(i), E, K-Ic and gamma(f), and lower values of B compared to leucite-based glass-ceramic and porcelains. Positive correlations were observed for sigma(i) versus K-Ic, and K-Ic versus E-1/2, however, E did not show relationship with HV and B. The increase of crystalline phase content is beneficial to decrease the brittleness of dental ceramics by means of both an increase in fracture surface energy and a lowering in index of brittleness. (C) 2012 Elsevier Ltd and Techna Group Sri. All rights reserved.

Bacterial leakage along the implant-abutment interface: culture and DNA Checkerboard hybridization analyses

Objective Bacterial species have been found harboring the internal surface of dental implants as consequence of their failed connections. The aim of the present study was to compare the detection frequency of bacterial leakage from human saliva through the implantabutment interface, under non-loading conditions, using either DNA Checkerboard or culture method. Materials and methods Thirty dental implants with hexagonal platforms were connected to pre-machined abutments according to the manufacturers specifications. The assemblies were individually incubated in human saliva under anaerobic conditions for 7 similar to days at 37 degrees C. Afterward, contents from the inner parts of the implants were collected and evaluated with either DNA Checkerboard (s similar to=similar to 15) or culture (n similar to=similar to 15). Subsequently, identification and quantitation of bacterial species from saliva and implants were carried out for the group evaluated with the DNA Checkerboard method. Results Both DNA Checkerboard and culture showed positive signals of bacterial leakage in 6 of the 15 evaluated samples. Capnocytophaga gingivalis and Streptococcus mutans were the most frequently detected species harboring the internal surface of the implants followed by Veillonella parvula. Conclusion Occurrence of bacterial leakage along the implantabutment interface is comparably detected with both DNA Checkerboard hybridization and conventional culture methods.

Influence of dental materials used for sealing caries lesions on laser fluorescence measurements

The aim of this study was to determine the influence of thickness and aging on the intrinsic fluorescence of sealing materials and their ability to block fluorescence from the underlying surface as assessed using a laser fluorescence device. Cavities of 0.5 mm and 1 mm depth were drilled into acrylic boards which were placed over two surfaces with different fluorescence properties: a low-fluorescence surface, to assess the intrinsic fluorescence of the sealing materials, and a high-fluorescence surface, to assess the fluorescence-blocking ability of the sealing materials. Ten cavities of each depth were filled with different sealing materials: Adper Scotchbond Multi-Purpose, Adper Single Bond 2, FluroShield, Conseal f and UltraSeal XT Plus. Fluorescence was measured with a DIAGNOdent pen at five different time points: empty cavity, after polymerization, and 1 day, 1 week and 1 month after filling. The individual values after polymerization, as well as the area under the curve for the different periods were submitted to ANOVA and the Tukey test (p < 0.05). At 0.5 mm, Scotchbond, FluroShield and UltraSeal showed insignificant changes in intrinsic fluorescence with aging and lower fluorescence after polymerization than Single Bond and Conseal. At 1 mm, Scotchbond and FluroShield showed the lowest intrinsic fluorescence, but only Scotchbond showed no chagnes in fluorescence with aging. At both depths, Scotchbond blocked significantly less fluorescence. All sealing materials blocked more fluorescence when applied to a depth of 1 mm. At 0.5 mm, fissure sealants blocked more fluorescence than adhesives, and did not show significant changes with aging. Scotchbond had the least affect on the fluorescence from the underlying surface and would probably have the least affect on the monitoring of sealed dental caries by laser fluorescence.