Processamento e interpretação de dados 2D e 3D de GPR :aplicações no imageamento de feições kársticas e estruturas de dissolução no campo de petróleo de Fazenda Belém-CE

In Fazenda Belém oil field (Potiguar Basin, Ceará State, Brazil) occur frequently sinkholes and sudden terrain collapses associated to an unconsolidated sedimentary cap covering the Jandaíra karst. This research was carried out in order to understand the mechanisms of generation of these collapses. The main tool used was Ground Penetrating Radar (GPR). This work is developed twofold: one aspect concerns methodology improvements in GPR data processing whilst another aspect concerns the geological study of the Jandaíra karst. This second aspect was strongly supported both by the analysis of outcropping karst structures (in another regions of Potiguar Basin) and by the interpretation of radargrams from the subsurface karst in Fazenda Belém. It was designed and tested an adequate flux to process GPR data which was adapted from an usual flux to process seismic data. The changes were introduced to take into account important differences between GPR and Reflection Seismic methods, in particular: poor coupling between source and ground, mixed phase of the wavelet, low signal-to-noise ratio, monochannel acquisition, and high influence of wave propagation effects, notably dispersion. High frequency components of the GPR pulse suffer more pronounced effects of attenuation than low frequency components resulting in resolution losses in radargrams. In Fazenda Belém, there is a stronger need of an suitable flux to process GPR data because both the presence of a very high level of aerial events and the complexity of the imaged subsurface karst structures. The key point of the processing flux was an improvement in the correction of the attenuation effects on the GPR pulse based on their influence on the amplitude and phase spectra of GPR signals. In low and moderate losses dielectric media the propagated signal suffers significant changes only in its amplitude spectrum; that is, the phase spectrum of the propagated signal remains practically unaltered for the usual travel time ranges. Based on this fact, it is shown using real data that the judicious application of the well known tools of time gain and spectral balancing can efficiently correct the attenuation effects. The proposed approach can be applied in heterogeneous media and it does not require the precise knowledge of the attenuation parameters of the media. As an additional benefit, the judicious application of spectral balancing promotes a partial deconvolution of the data without changing its phase. In other words, the spectral balancing acts in a similar way to a zero phase deconvolution. In GPR data the resolution increase obtained with spectral balancing is greater than those obtained with spike and predictive deconvolutions. The evolution of the Jandaíra karst in Potiguar Basin is associated to at least three events of subaerial exposition of the carbonatic plataform during the Turonian, Santonian, and Campanian. In Fazenda Belém region, during the mid Miocene, the Jandaíra karst was covered by continental siliciclastic sediments. These sediments partially filled the void space associated to the dissolution structures and fractures. Therefore, the development of the karst in this region was attenuated in comparison to other places in Potiguar Basin where this karst is exposed. In Fazenda Belém, the generation of sinkholes and terrain collapses are controlled mainly by: (i) the presence of an unconsolidated sedimentary cap which is thick enough to cover completely the karst but with sediment volume lower than the available space associated to the dissolution structures in the karst; (ii) the existence of important structural of SW-NE and NW-SE alignments which promote a localized increase in the hydraulic connectivity allowing the channeling of underground water, thus facilitating the carbonatic dissolution; and (iii) the existence of a hydraulic barrier to the groundwater flow, associated to the Açu-4 Unity. The terrain collapse mechanisms in Fazenda Belém occur according to the following temporal evolution. The meteoric water infiltrates through the unconsolidated sedimentary cap and promotes its remobilization to the void space associated with the dissolution structures in Jandaíra Formation. This remobilization is initiated at the base of the sedimentary cap where the flow increases its abrasion due to a change from laminar to turbulent flow regime when the underground water flow reaches the open karst structures. The remobilized sediments progressively fill from bottom to top the void karst space. So, the void space is continuously migrated upwards ultimately reaching the surface and causing the sudden observed terrain collapses. This phenomenon is particularly active during the raining season, when the water table that normally is located in the karst may be temporarily located in the unconsolidated sedimentary cap

Proposta metodológica para o imageamento, caracterização, parametrização e geração de modelos virtuais de afloramentos

The aim of this work was to describe the methodological procedures that were mandatory to develop a 3D digital imaging of the external and internal geometry of the analogue outcrops from reservoirs and to build a Virtual Outcrop Model (VOM). The imaging process of the external geometry was acquired by using the Laser Scanner, the Geodesic GPS and the Total Station procedures. On the other hand, the imaging of the internal geometry was evaluated by GPR (Ground Penetrating Radar).The produced VOMs were adapted with much more detailed data with addition of the geological data and the gamma ray and permeability profiles. As a model for the use of the methodological procedures used on this work, the adapted VOM, two outcrops, located at the east part of the Parnaiba Basin, were selected. On the first one, rocks from the aeolian deposit of the Piaui Formation (Neo-carboniferous) and tidal flat deposits from the Pedra de Fogo Formation (Permian), which arises in a large outcrops located between Floriano and Teresina (Piauí), are present. The second area, located at the National Park of Sete Cidades, also at the Piauí, presents rocks from the Cabeças Formation deposited in fluvial-deltaic systems during the Late Devonian. From the data of the adapted VOMs it was possible to identify lines, surfaces and 3D geometry, and therefore, quantify the geometry of interest. Among the found parameterization values, a table containing the thickness and width, obtained in canal and lobes deposits at the outcrop Paredão and Biblioteca were the more relevant ones. In fact, this table can be used as an input for stochastic simulation of reservoirs. An example of the direct use of such table and their predicted radargrams was the identification of the bounding surface at the aeolian sites from the Piauí Formation. In spite of such radargrams supply only bi-dimensional data, the acquired lines followed of a mesh profile were used to add a third dimension to the imaging of the internal geometry. This phenomenon appears to be valid for all studied outcrops. As a conclusion, the tool here presented can became a new methodology in which the advantages of the digital imaging acquired from the Laser Scanner (precision, accuracy and speed of acquisition) were combined with the Total Station procedure (precision) using the classical digital photomosaic technique

Tropical dermatology: Venomous arthropods and human skin Part I. Insecta

Although many tropical insects carry infectious diseases, cutaneous injury can occur by other mechanisms, for example erucism (envenomation by caterpillars) or lepidopterism (dermatitis from moths). Pararama is a unique form of erucism seen in workers in contact with rubber trees in the Amazon, and it is caused by Premolis larvae, resulting in progressive periarticular fibrosis, ankylosis, and the loss of articulation. Ants and aquatic insects of the Belostomatidae family can cause painful bites and stings. Anaphylactic shock and death can result from the venom of bees and wasps. Beetles can cause vesicular dermatitis via cantharidin or paederin. Myiasis results from fly larvae (maggots) feeding on live or necrotic tissue of humans or other hosts, while New World screwworm fly larvae feed only on living tissue and burrow (ie, screw) more deeply when attempts are made to remove them. Tungiasis is characterized by very pruritic and painful papules and ulcers resulting from a Tunga flea penetrating the host's skin. Dermatologists should be able to diagnose and treat the cutaneous manifestations of these tropical insects and educate their patients on prevention. (J Am Acad Dermatol 2012; 67:339.e1-14.)

Uso do GPR na geração de modelos estáticos 3D para o planejamento de lavra de minerais pesados depositados em dunas eólicas

This project was developed as a partnership between the Laboratory of Stratigraphical Analyses of the Geology Department of UFRN and the company Millennium Inorganic Chemicals Mineração Ltda. This company is located in the north end of the paraiban coast, in the municipal district of Mataraca. Millennium has as main prospected product, heavy minerals as ilmenita, rutilo and zircon presents in the sands of the dunes. These dunes are predominantly inactive, and overlap the superior portion of Barreiras Formation rocks. The mining happens with the use of a dredge that is emerged at an artificial lake on the dunes. This dredge removes sand dunes of the bottom lake (after it disassembles of the lake borders with water jets) and directs for the concentration plant, through piping where the minerals are then separate. The present work consisted in the acquisition external geometries of the dunes, where in the end a 3D Static Model could be set up of these sedimentary deposits with emphasis in the behavior of the structural top of Barreiras Formation rocks (inferior limit of the deposit). The knowledge of this surface is important in the phase of the plowing planning for the company, because a calculation mistake can do with that the dredge works too close of this limit, taking the risk that fragments can cause obstruction in the dredge generating a financial damage so much in the equipment repair as for the stopped days production. During the field stages (accomplished in 2006 and 2007) topographical techniques risings were used with Total Station and Geodesic GPS as well as shallow geophysical acquisitions with GPR (Ground Penetrating Radar). It was acquired almost 10,4km of topography and 10km of profiles GPR. The Geodesic GPS was used for the data geopositioning and topographical rising of a traverse line with 630m of extension in the stage of 2007. The GPR was shown a reliable method, ecologically clean, fast acquisition and with a low cost in relation to traditional methods as surveys. The main advantage of this equipment is obtain a continuous information to superior surface Barreiras Formation rocks. The static models 3D were elaborated starting from the obtained data being used two specific softwares for visualization 3D: GoCAD 2.0.8 and Datamine. The visualization 3D allows a better understanding of the Barreiras surface behavior as well as it makes possible the execution of several types of measurements, favoring like calculations and allowing that procedures used for mineral extraction is used with larger safety

As dunas eólicas de Natal/RN: datação e evolução

The main purpose of this study is to present complementary information on eolian systems that occur in the Center-South portion of the city of Natal, Rio Grande do Norte State, Brazil. The investigation focused on the identification of eolian units, absolute luminescence dating of eolian sediments, to geophysical analysis by Ground Penetrating Radar (GPR), as well as qualitative identification of the use and terrain occupation in the study area. A map was elaborated in order to separate eolian geological units, and describe their deposicional and erosional characteristics, by aerial photo-interpretation. The study lead to the identification of six main units: Unit I - Blowouts (BW), Unit II - Active dunes field (DA), Unit III - Fixed dunes field (DF), Unit IV - Parabolic dunes field (DP), Unit V - Red parabolic dunes field (DV) and Unit VI - Devastated dunes surface (SD). Were analised by Termoluminescense (TL) Method Eight samples from units I, III, IV and V. The largest number of samples with similar or close resulted yielded ages about 15,000 years. Two GPR profiles were obtained in areas of the Dunes Park, near the "Natal s Conventions Center". Results showed the migration a new dune generation over on older one, the geologic contact between dunes and the Formação Barreiras (FB), and the groundwater level inside the dune unit. The qualitative study on the use and terrain occupation of the soil in some dunes fields in the study area, it was possible identify some use and occupation, as the following ones: the construction of residential and commercial buildings, dunes fields cutted for construction to access road and garbage deposition

Caracterização da geometria de depósitos sedimentares na borda sudoeste da Bacia`Potiguar

This study focuses on the potential of several techniques used to identify depositional geometries and paleogeographical investigation on the SW border of the Potiguar Basin. Three areas were selected for an integrated geological, geophysical and geochemistry study. The main used techniques were facies analysis, remote sensing,ground penetrating radar (GPR) and gamma-ray in outcrops, as well as petrographic microscope observations and the using of scanning eletronic microscopic (SEM), and Carbon and Oxygen Isotopic study in the carbonate tufa. These methodological approaches were very efficient in the facies analysis of 2D geometries. The GPR profiles carried out in Quixeré identified important geological reflectors which allowed to the identification of depositional geometries of tufa. However, GPR profiles were not able to identify geological reflectors in the Apodi and Olho d´Água da Bica outcrops. Gammaray profiles also presented good results, which justify their use in 1D and 2D geometric analysis. Carbon and Oxygen Isotopic analyses were also used to investigate paleoenvironmental setting of tufa deposits. It is important to remark the excellent resultsof GRP using in the identification of deposition al geometries of tufa and their contact relationships with the underlying rocks. Field analysis of faults indicate a vertical sigma-1 orientation which was associated to normal faults

Mapeamento digital de análogos a reservatórios petrolíferos: exemplos para depósitos fluviais da Unidade Açu-3 - Bacia Potiguar

In the current work are presented the results about the study of digital mapping of analogs referents the fluvial oil reservoirs in the Açu Formation. With the regional recognizing in the south corner of Potiguar Basin was selected a area of 150 Km square in the west of Assu city. In this area was chosen the outcrops for the digital mapping and from the data fields and remote sensors were done the depositional architectural for the fluvial deposits, which it was named coarse meandering fluvial systems. In the deposits were individualized 3 (three) fluvial cycles, which they was separated by bounding surface of fifth order. Such cycles are preferentially sandy, with fining-upward sequence finished in flood plain deposits. Inner of the sandy levels of the filling channels were characterized least cycles, normaly incomplete, constituted by braided sandy bodies and bounding surfaces of fourth order. In the mapped area was chosen a outcrop with great exposition, where it was possible to see tipical deposits of filling channel and was in this outcrop that was done the digital mapping. In this outcrop was used diverse technics and tools, which they integrated sedimentological, altimetric (GPS, Total Station), LIDAR (Light Detection and Ranging), digital photomosaic of high resolution and of the inner geometries (Ground Penetration Radar) data sets. For the integrating, interpretation and visualization of data was used software GoCAD®. The final product of the outcrop digital mapping was the photorealistic model of part of the cliff (or slope) because the observed reflectors in the radargrams were absents. A part of bar oblique accretion was modeled according to GPR gride of 200x200 meters in the alluvial Assu river probable recent analog. With the data of inner geometries was developed the three-dimentional sedimentary architectural, where it was possible characterize sand sheet deposits and many hierarchy of braided channels. At last, simulations of sedimentary geometries and architectures of the Potiguar Basin Fluvial Reservoirs were done with PetBool software, in order to understand the capacity of this program in simulations with a lot of numbers of conditioning wells. In total, 45 simulations was acquired, where the time and the channel numbers increase in relation of the conditioning wells quantity. The deformation of the meanders was detected from the change of simulated dominion dimensions. The presence of this problem was because the relationship between the simulated dominion and the width of the meander

Dois testes de imageamento com GPR em problemas de controle ambiental em regiões tropicais: migração de dunas e localização de dutos de óleo enterrados

Because the penetration depth of Ground Penetrating Radar (GPR) signals is very limited in high conductive soils, the usefullness of this method in tropical regions is not yet completly known. The main objective of this researh is to test the usefullness of the method in Brazil. Two typical problems where GPR has been used in Europe and North American were choosed for this test: the first one is to characterize the internal structures of a sand body and the second problem is the localization of old buried pipes lines. The first test was done near the city of São Bento do Norte, in the northern coast of Rio Grande do Norte state, NE Brazil. In this region, there is a sand dune that is migrating very fast in the direction of adjacent settling areas. To characterize the internal structure of the dune and its relationship to the prevailing wind direction, as a preliminary step to understand the dune migration, GPR profiles using the 400 MHz frequency were performed in E-W, N-S, NE-SW, and SE-NW directions over the sand dune intersecting at the top of the dune. The practical resolution of the GPR data is around 30 cm; this was sufficient to distinguish individual foresets inside the dune. After applying the elevation correction to the data, we identified that dips of bedding structures are smallest for the N-S profile, which is perpendicular to the dominant wind direction, largest for the E-W profile, and intermediate for the SW-NE and SE-NW profiles. Foresets in the E-W profile dip with angles varying from 2 to 6 degrees. In the E-W profile, the water table and a horizontal truncation interface separating two generations of dunes were identified, as well as an abrupt directional change in the foreset patterns associated to a lateral contact between two dune generations, the older one extending to the west. The used high frequency of 400 Mhz does not allow a penetration deep enough to map completely these internal contacts. The second test was done near Estreito, a small town near Carnaúbais city, also in Rio Grande do Norte state. In this locality, there are several old pipe lines buried in area covered by plantations where digging should be minimized. Several GPR profiles using the 400 and 200 MHz frequency were performed trying to intercept perpendicularly the possible pipe lines. Because of the high conductivity of the soil, the raw original data can hardly be use to identify the pipe lines. However, after an adequate processing over the 200 MHz profiles, six pipe lines were identified. As a global result of the tests, GPR can be very usefull if the conductivity of the ground is low or, in the case of medium conductivities of the soils, if adequate processing is performed

Iinterpretação conjunta de dados de GPR e medidas de permeabilidade sobre um análogo de reservatório siliciclástico falhado na bacia de Tucano, no NE do Brasil

It is presented an integrated geophysical investigation of the spatial distribution of faults and deformation bands (DB´s) in a faulted siliciclastic reservoir analogue, located in Tucano Basin, Bahia State, northeastern Brazil. Ground Penetrating Radar (GPR) and permeability measurements allowed the analysis of the influence of DB´s in the rock permeability and porosity. GPR data were processed using a suitable flow parametrization in order to highlight discontinuities in sedimentary layers. The obtained images allowed the subsurface detection of DB´s presenting displacements greater that 10 cm. A good correlation was verified between DB´s detected by GPR and those observed in surface, the latter identified using conventional structural methods. After some adaptations in the minipermeameter in order to increase measurement precision, two approaches to measure permeabilities were tested: in situ and in collected cores. The former approach provided better results than the latter and consisted of scratching the outcrop surface, followed by direct measurements on outcrop rocks. The measured permeability profiles allowed to characterize the spatial transition from DB´s to undeformed rock; variation of up to three orders of magnitude were detected. The permeability profiles also presented quasi-periodic patterns, associated with textural and granulometric changes, possibly associated to depositional cycles. Integrated interpretation of the geological, geophysical and core data, provided the subsurface identification of an increase in the DB´s number associated with a sedimentary layer presenting granulometric decrease at depths greater than 8 m. An associated sharp decrease in permeability was also measured in cores from boreholes. The obtained results reveal that radagrams, besides providing high resolution images, allowing the detection of small structures (> 10 cm), also presented a correlation with the permeability data. In this way, GPR data may be used to build upscaling laws, bridging the gap between outcrop and seismic data sets, which may result in better models for faulted reservoirs

Uso do gpr na caracterização da pluma de contaminação gerada por hidrocarbonetos a partir de um posto de combustível na praia de Búzios/RN

This work is the application of geophysical methods, using the Ground Penetrating Radar (GPR), with the objective of survey in a subsurface plume of contamination caused by a disabled gas station. The gas station is located on the Búzios beach in southern coast of the state to Rio Grande do Norte in an Area of Environmental Protection called Bonfim-Guaraíra. The interest to develop this work was the presence of contaminants (hydrocarbons) in a well located on the desktop, previously used for the abstraction of groundwater for residents living near the site. Were raised 15 geophysical survey lines totaling 775,48 lifting and installed 4 piezometer, to confirm the contamination and prepare a pluviometric map that helped in indicating the direction of local groundwater flow, thus showing the direction of movement of the probably plume of contamination. From the processing of the GPR lines was possible to identify two likely phases of contamination according to the classification proposed by Azambuja et al 2000, which are called phase absorbed and dissolved phase

Interpretação de dados de GPR com base na hierarquização de superfícies limitantes e na adaptação de critérios sismoestratigráficos

Due to its high resolution, Ground Penetrating Radar (GPR) has been used to image subsurface sedimentary deposits. Because GPR and Seismic methods share some principles of image construction, the classic seismostratigraphic interpretation method has been also applied as an attempt to interpret GPR data. Nonetheless some advances in few particular contexts, the adaptations from seismic to GPR of seismostratigraphic tools and concepts unsuitable because the meaning given to the termination criteria in seismic stratigraphy do not represent the adequate geologic record in the GPR scale. Essentially, the open question relies in proposing a interpretation method for GPR data which allow not only relating product and sedimentary process in the GPR scale but also identifying or proposing depositional environments and correlating these results with the well known Sequence Stratigraphy cornerstones. The goal of this dissertation is to propose an interpretation methodology of GPR data able to perform this task at least for siliciclastic deposits. In order to do so, the proposed GPR interpretation method is based both on seismostratigraphic concepts and on the bounding surface hierarchy tool from Miall (1988). As consequence of this joint use, the results of GPR interpretation can be associated to the sedimentary facies in a genetic context, so that it is possible to: (i) individualize radar facies and correlate them to the sedimentary facies by using depositional models; (ii) characterize a given depositional system, and (iii) determine its stratigraphic framework highligthing how it evolved through geologic time. To illustrate its use the proposed methodology was applied in a GPR data set from Galos area which is part of the Galinhos spit, located in Rio Grande do Norte state, Northeastern Brazil. This spit presents high lateral sedimentary facies variation, containing in its sedimentary record from 4th to 6th cicles caused by high frequency sea level oscillation. The interpretation process was done throughout the following phases: (i) identification of a vertical facies succession, (ii) characterization of radar facies and its associated sedimentary products, (iii) recognition of the associated sedimentary process in a genetic context, and finally (iv) proposal of an evolutionay model for the Galinhos spit. This model proposes that the Galinhos spit is a barrier island constituted, from base to top, of the following sedimentary facies: tidal channel facies, tidal flat facies, shore facies, and aeolic facies (dunes). The tidal channel facies, in the base, is constituted of lateral accretion bars and filling deposits of the channels. The base facies is laterally truncated by the tidal flat facies. In the foreshore zone, the tidal flat facies is covered by the shore facies which is the register of a sea transgression. Finally, on the top of the stratigraphic column, aeolic dunes are deposited due to areal exposition caused by a sea regression

Proposta metodológica para o imageamento digital e modelagem virtual 3d de um bloco de rochas travertinas

In this paper we present the methodological procedures involved in the digital imaging in mesoscale of a block of travertines rock of quaternary age, originating from the city of Acquasanta, located in the Apennines, Italy. This rocky block, called T-Block, was stored in the courtyard of the Laboratório Experimental Petróleo "Kelsen Valente" (LabPetro), of Universidade Estadual de Campinas (UNICAMP), so that from it were performed Scientific studies, mainly for research groups universities and research centers working in brazilian areas of reservoir characterization and 3D digital imaging. The purpose of this work is the development of a Model Solid Digital, from the use of non-invasive techniques of digital 3D imaging of internal and external surfaces of the T-Block. For the imaging of the external surfaces technology has been used LIDAR (Light Detection and Range) and the imaging surface Interior was done using Ground Penetrating Radar (GPR), moreover, profiles were obtained with a Gamma Ray Gamae-spectômetro laptop. The goal of 3D digital imaging involved the identification and parameterization of surface geological and sedimentary facies that could represent heterogeneities depositional mesoscale, based on study of a block rocky with dimensions of approximately 1.60 m x 1.60 m x 2.70 m. The data acquired by means of terrestrial laser scanner made available georeferenced spatial information of the surface of the block (X, Y, Z), and varying the intensity values of the return laser beam and high resolution RGB data (3 mm x 3 mm), total points acquired 28,505,106. This information was used as an aid in the interpretation of radargrams and are ready to be displayed in rooms virtual reality. With the GPR was obtained 15 profiles of 2.3 m and 2 3D grids, each with 24 sections horizontal of 1.3 and 14 m vertical sections of 2.3 m, both the Antenna 900 MHz to about 2600 MHz antenna. Finally, the use of GPR associated with Laser Scanner enabled the identification and 3D mapping of 3 different radarfácies which were correlated with three sedimentary facies as had been defined at the outset. The 6 profiles showed gamma a low amplitude variation in the values of radioactivity. This is likely due to the fact of the sedimentary layers profiled have the same mineralogical composition, being composed by carbonate sediments, with no clay in siliciclastic pellitic layers or other mineral carrier elements radioactive

Caracterização geológica tridimensional e monitoramento de dunas no litoral oriental do Rio Grande do Norte

This work presents geophysical and geological results obtained in a dunefield located in the east coast of Rio Grande do Norte State, with the aim to recognize the aeolian body depositional geometries to a future geologic modeling of the aeolian petroliferous reservoirs. The research, which was done in blowouts region situated at Nisia Floresta Municipally, included the characterization of external geometries with GPS and internal geometry analysis by GPR. Data was integrated in GoCAD software, where it was possible the three-dimensional characterization and interpretation of the studied deposits. The interpretation of GPR profiling allowed identifying: First-order bounding surfaces that separated the aeolian deposits of the Barreiras Formation rocks; Second-order bounding surfaces, which limit dune generations and Third-order bounding surfaces, a reactivation surface. This classification was based and adapted by the Brookfield (1977) and Kocurek (1996) propose. Four radarfacies was recognized: Radarfacies 1, progradational reflectors correlated to foresets of the dunes, Radarfacies 2, plain parallels reflectors related to sand sheets, Radarfacies 3, plain parallels reflectors associated to reworking of the blowout dune crest and Radarfacies 4, mounded reflectors associated to vegetated mound of sand or objects buried in subsurface. The GPR and GPS methods was also employed to the monitoring of dunefields susceptible to human activities in Buzios Beach, where the constructions along the blowout region and the tourism are changing the natural evolution of the deposits. This fact possibly to cause negative impacts to the coastal zone. Data obtained in Dunas Park, a unit environmental conservation, was compared with information of the Buzios Beach. There is a major tendency of erosion in Buzios, specifically in blowout corridor and blowout dune

Effect of fluid resins on the surface roughness and topography of resin composite restorations analyzed by atomic force microscope

The aim of the study was to verify the influence of surface sealants on the surface roughness of resin composite restorations before and after mechanical toothbrushing, and evaluate the superficial topography using atomic force microscope. Five surface sealers were used: Single Bond, Opti Bond Solo Plus, Fortify, Fortify Plus and control, without any sealer agent. The lowest values of surface roughness were obtained for control, Single Bond and Fortify groups before toothbrushing. Fortify and Fortify Plus were the sealer agents that support the abrasive action caused by the toothbrushing although Fortify Plus group remained with high values of surface roughness. The application of specific surface sealants could be a useful clinical procedure to maintain the quality of resin-based composite restorations. (C) 2010 Elsevier Ltd. All rights reserved.

Assessing the surface roughness of a posterior resin composite: effect of surface sealing

This study assessed the in vitro influence of surface sealing on the surface roughness of a posterior resin composite before and after tooth-brushing. Thirty. specimens (13 nun diameter x 1 mm high) were fabricated from Filtek-P60 resin composite and randomly assigned to three groups (n=10): a non-sealed control and two groups sealed with one of the tested materials-a surface-penetrating sealant (Protect-it!-PI) and a one bottle adhesive system (Single Bond-SB). The samples were subjected to a surface roughness reading to determine the initial roughness, then submitted to simulated toothbrushing with 35,600 cycles for 100 minutes. Specimens were then cleaned and a post-abrasion surface roughness reading accomplished. Means (pm), recorded before (B) and after (A) toothbrushing, and standard deviations were: Control-(B): 0.032 (+/-0.005), (A): 0.054 (+/-0.005); PI-(B): 0.034 (+/-0.005), (A): 0.060 (+/-0.034); SB (B): 0.031 (+/-0.004), (A): 0.047 (+/-0.007). Data were tabulated and submitted to two-way ANOVA. No statistically significant difference was observed when the control and experimental groups were compared. However, a significant difference (p<0.05) was found between the measurements performed before and after toothbrushing. Based on these results, it may be concluded that using either a surface penetrating sealant or a one bottle adhesive system did not provide the optimization of superficial integrity. The use of a dentifrice and toothbrush resulted in significant alterations to the surface smoothness of the resin composite.