Socket shield technique: Stress distribution analysis.

Background: To analyze through finite element analysis the stress distribution in peri-implant bone tissues, implants, and prosthetic components induced by the socket shield (SS) technique in comparison to other techniques used to treat tooth loss. Materials and Methods: A three-dimensional model of a superior central incisor crown supported by implant was modeled and three different placement conditions were simulated: SS - 2.0-mm-thick root dentin fragment positioned between the alveolar buccal wall and implant; heterologous bone graft (HBG) - bovine bone graft positioned the alveolar buccal wall and implant; and control (C) - implant fully placed in bone tissue of a healed alveolus. The model was restricted at the lateral surfaces of the bone tissue and the following loads were simulated: Both oblique (45°) loads of 100 N on the lingual surface of the crown (maximal habitual intercuspation) and 25.5 N on the incisal edge of the crown (tooth contact during mandibular protrusion) were simultaneously applied. Tensile stress, shear stress, compression, and displacement were analyzed in the cortical bone, trabecular bone, dentin root fragment, and bone graft; while equivalent von Mises stresses were quantified in the implant and prosthetic components. Results: Stress values of SS and HBG in the bone tissues were higher than C, while slight differences within models were observed for dentin root fragment, bone graft, implant, and prosthetic components. Conclusions: The SS technique presented the highest stress concentration in the peri-implant tissues.

Seropositivity to Cysticercosis in School-Age Children Living in a Low-Income Municipality in the Midwest Region of Brazil.

Background: Human cysticercosis (CC) is a global public health problem, especially in Latin America, including Brazil. We aimed to analyze the seroprevalence of CC among school-age children and adolescents. Methods: We analyzed the presence of specific IgG antibodies against Taenia solium metacestodes in 500 serum samples from elementary school children and adolescents in Jataí City, state of Goiás, Brazil. IgG antibodies against the antigenic extract of the parasite were detected and analyzed by ELISA, and specific peptides were identified by confirmatory Western Blotting test. Results: Of the 500 study participants, 205 (41%) were male, and 295 (59%) were female. Participants aged between 4 and 18 years (mean age 8.4 years). The percentage of serum samples reactive by ELISA was 37.2%. These samples were analyzed by Western Blotting, which confirmed that the seropositivity rate was 6.2% (95% CI 2.4-14.7) in 31 samples reactive for CC-specific bands, determined in serum samples from 18 male (5-11 years old) and 13 female (4-12 years old) students. Conclusion: The CC seroprevalence demonstrated in schoolchildren suggests that this parasitosis is endemic in the study area. Further investigations are necessary to clarify the local epidemiology of this parasitosis.

Dental pain in adult and elderly homeless people: Prevalence, associated factors, and impact on the quality of life in Midwest Brazil.

OBJECTIVES: To investigate the prevalence and factors associated with dental pain and its impact on the quality of life of adult and elderly homeless people in Midwest Brazil. METHODS: A cross-sectional study was conducted with 353 individuals aged ≥18 attending a public homeless shelter in a Brazilian state capital (Goiânia). Data on sociodemographic, psychosocial, drug use and oral health-related factors, and quality of life [Oral Impact on Daily Performance scale (OIDP)] were collected through interviews. Pearson's Chi-square tests and robust Poisson regression were used for statistical analysis. RESULTS: The prevalence of dental pain in the past 6 months was 50 percent. Most of the respondents reported very severe pain and self-management including medication and tooth extraction. In the adjusted regression, the prevalence of pain was 1.48 times higher among individuals who last visited the dentist within the past 2 years, compared to those who had visited more than 2 years ago; and nearly five times higher among those with a perceived need for dental treatment, compared to those with no need. The prevalence of oral impact on daily performance was 80.1 percent and the most affected activities were "difficulty eating" and "feeling ashamed to smile or speak." The adjusted prevalence of impact was higher among individuals who had dental pain, regardless of their sociodemographic characteristics. CONCLUSIONS: The prevalence, intensity, and self-management of dental pain were high among the Brazilian homeless people studied. Reporting of pain was associated with factors related to dental care and negatively affected their quality of life.

Satisfaction with oral health and associated factors among homeless people in Midwest Brazil.

BACKGROUND: Self-perceived oral health has been extensively investigated, but studies on homeless people are scarce, and there is currently no evidence from Latin America. OBJECTIVE: To investigate the prevalence and factors associated with satisfaction with the oral health of homeless individuals in one Brazilian capital of the Midwest region. SUBJECT AND METHODS: A cross-sectional study was carried out with 351 adult individuals attending a temporary public shelter who were interviewed about sociodemographic and psychosocial aspects, drugs use and oral health. The outcome was satisfaction with oral health (satisfied/dissatisfied). Pearson's chi-square test and Poisson regression with robust variance were used for statistical analysis. RESULTS: The prevalence of dissatisfaction with oral health was 68.9% (95% CI = 63.9-73.6). After adjusting for covariates, dissatisfaction was more frequent among individuals who were married/in a stable relationship (PR = 1.18; 95% CI = 1.02-1.36), with felt need for treatment (PR = 2.27; 95% CI = 1.23-4.17) or complete prosthesis (PR = 1.35; 95% CI = 1.18-1.55), and those who used illicit drugs in the past six months (PR = 1.22; 95% CI = 1.06-1.39). CONCLUSION: The prevalence of dissatisfaction with oral health in the homeless individuals studied was high and associated with their marital status, use of illicit drugs and self-reported need for dental treatment and complete prosthesis.

Significance of immediate dentin sealing and flowable resin coating reinforcement for unfilled/lightly filled adhesive systems.

BACKGROUND: Immediate dentin sealing implies applying an adhesive system to dentin directly after tooth preparation, before impression. The technique is universal (inlays, onlays, veneers, crowns) and well documented clinically and experimentally. Different types of dentin bonding agents (DBAs) are available on the market. Major differences lie in the thickness of the hybrid layer and overlaying adhesive resin (filled vs. unfilled/lightly filled adhesives). OBJECTIVE: The objective of this work is to provide precise clinical instructions and present new experimental data about the bond strength of five DBAs (Optibond FL, Scotchbond MP, Single Bond Plus, Clearfil SE Bond, and Scotchbond Universal) used conventionally (dentin sealed at the time of restoration delivery) or with immediate dentin sealing, as well as with an additional flowable resin coating. METHODS: Seventy-five human molars were selected, restored/tested according the microtensile bond strength method. Fifteen groups (n=5) were obtained from the combination of the five DBAs and three application modes: delayed dentin sealing, immediate dentin sealing and immediate dentin sealing with flowable resin coating. RESULTS: It appears that immediate dentin sealing was confirmed to significantly improve the bond strength of all tested adhesives. The use of a flowable resin coating reinforcement after immediate dentin sealing increased the microtensile bond strength of all unfilled/lightly filled adhesives (from 233% of increase for ScotchBond MP, up to 560% for Clearfil SE Bond) and maintained the performance of the 3-step golden standard adhesive. Optibond FL used with (52.51 MPa) or without (54.75 MPa) additional flowable resin coating and Clearfil SE Bond (45.64 MPa) used with flowable resin coating provided the best results. CLINICAL SIGNIFICANCE: The original immediate dentin sealing (IDS) technique implies the use of a filled DBA. With unfilled/lightly filled adhesives, it is suggested to reinforce IDS with an additional flowable resin coating. This seems especially paramount to the performance of simplified adhesive systems to protect the thin bonding interface from oxygen inhibition and preserve IDS layer during predelivery cleaning of the preparation. The clinical reinforcement of unfilled/lightly filled IDS with flowable resin composite is encouraged for more predictable bonding.

Resin Cement: Correspondence with Try-In Paste and Influence on the Immediate Final Color of Veneers.

PURPOSE: To assess the correspondence of shades between try-in pastes and resin cements and their influence on the final color of veneers. MATERIALS AND METHODS: Bovine teeth (n = 140) were prepared and divided into 2 groups (a or b) according to ceramic veneer thickness (0.35 or 0.70 mm). Seventy teeth (n = 70) were distributed in 7 groups (groups 1 to 7a and groups 1 to 7b; n = 10). Try-in pastes and their corresponding resin cements were used according to the value: groups 1a and 1b (value -3); groups 2a and 2b (-2); groups 3a and 3b (-1); groups 4a and 4b (0); groups 5a and 5b (+1); groups 6a and 6b (+2); groups 7a and 7b (+3). Color measurements were performed with spectrophotometer, and the coordinates L* , a* , and b* were obtained. The final color change (ΔE) was calculated from these coordinates: ΔE0 (trial - substrate), ΔE1 (cementation - substrate), and ΔE2 (cementation - trial). The data were analyzed using the Kolmogorov-Smirnov test, the Wilcoxon test, or t-test for paired samples and repeated-measures ANOVA, post hoc Bonferroni, or the Friedman test (p < 0.05). RESULTS: The results indicated no statistically significant difference between the groups comparing ΔE0 and ΔE1 for 0.35 mm thickness laminate veneers, except for groups 2a and 5a. For 0.70 mm thickness laminate veneers, no statistically significant differences were observed between the groups comparing ΔE0 and ΔE1. ΔE2 values for 0.35 mm and 0.70 mm thickness laminate veneers ranged from 1.77 ± 0.81 to 4.99 ± 3.80 and from 1.01 ± 0.73 to 4.66 ± 2.96, respectively. CONCLUSIONS: Try-in pastes correspond with their respective resin cements for most colors investigated. The color of the resin cement may influence the final color of laminate veneers. Thickness of the ceramic was the most relevant variable for color change.

Screening the use of informed consent forms prior to procedures involving operative dentistry: ethical aspects.

Background. The present study aimed to screen the knowledge and attitudes of dentists toward the use of informed consent forms prior to procedures involving operative dentistry. Methods. A research tool containing questions (questionnaire) regarding the use of informed consent forms was developed. The questionnaire consisted of seven questions structured to screen the current practice in operative dentistry towards the use of informed consent forms. Results. The questionnaires were distributed among 731 dentists, of which 179 returned them with answers. Sixty-seven dentists reported not using informed consent forms. The main reasons for not using informed consent forms were: having a complete dental record signed by the patient (67.2%) and having a good relation with patients (43.6%). The dentists who reported using informed consent forms revealed that they obtained them from other dentists and made their own modifications (35.9%). Few dentists revealed contacting lawyers (1.7%) and experts in legal dentistry (0.9%) for the development of their informed consent forms. Conclusion. A high number of dentists working in the field of operative dentistry behave according to the ethical standards in the clinical practice, becoming unprotected against ethical and legal actions.

Frequency of Root Canal Isthmi in Human Permanent Teeth Determined by Cone-beam Computed Tomography.

INTRODUCTION: This study evaluated the frequency of root canal isthmi (RCIs) in human permanent teeth by using cone-beam computed tomography. METHODS: A sample of 1400 teeth of 618 patients (394 women; mean age, 43.4 years) was selected. RCIs were detected longitudinally on 0.1-mm/0.1-mm axial slices of cone-beam computed tomography images of roots scanned from the pulp orifice to the apex, and findings were classified into 7 categories according to RCIs beginning and end: (1) both in the cervical third, (2) begin in the cervical third and end in the middle third, (3) begin in the cervical third and end in the apical third, (4) both in the middle third, (5) begin in the middle third and end in the apical third, (6) both in the apical third, or (7) no isthmus. A χ(2) test with Yates correction or the Fisher exact test was used to analyze categorical variables, described as frequencies (%). The Student t test was used to compare quantitative variables. RESULTS: RCI is a common anatomic structure in human permanent teeth, except in maxillary anterior teeth. CONCLUSIONS: The higher frequencies of RCIs (87.9%) were found in mandibular first molars. The frequencies of RCIs according to mean age and tooth group were not significantly different (P > .05), except in mandibular central incisors. RCIs were less frequent among older patients.

Polycyclic aromatic hydrocarbon concentrations in gas and particle phases and source determination in atmospheric samples from a semiurban area of Dourados, Brazil.

A headspace solid-phase microextraction (HS-SPME) procedure that employs a PDMS/DVB fiber was developed for the analysis of gas-phase polycyclic aromatic hydrocarbons (PAHs) collected in polyurethane foam (PUF) by gas chromatography (GC) mass spectrometry. The method exhibited good linearity (R (2) > 0.99) and repeatability (4.9-25 %) as well as an impressive detection limit that ranged from 1.1 to 3.3 ng. Twenty-two air samples were collected by high-volume samplers from January to November 2007 in a semiurban area of Dourados (Brazil) and were analyzed for their content of total suspended particulates and PAHs. The PAHs were extracted from the PUF samples using the developed procedure (HS-SPME), and PAHs adsorbed on particulate matter were extracted with dichloromethane/methanol (4:1 [v/v]) in an ultrasonic bath. The values of the total daily concentrations of 16 PAHs determined in the samples ranged from 0.375 to 8.407 ng m(-3). In addition, diagnostic ratios were calculated, showing that the PAHs in the atmosphere at the sampling site originated predominantly from vehicle emissions and the combustion of grass and wood. Hierarchical cluster analysis and principal component analysis were performed as well, the results of which indicated (1) the same sources of PAH identified by the diagnostic ratios and (2) that the sampling days could be categorized into three groups depending on the atmospheric conditions. GC retention indices were also used to identify PAHs, biphenyl (phenylbenzene), and heterocyclic organic compounds (benzofurans) in some of the samples.

The relationship between corn particle size and thermoregulation of laying hens in an equatorial semi-arid environment.

Heat stress is one of the main factors affecting egg production. One way to improve egg production is physical processing of the feed ingredients, allowing for better utilization of nutrients. In this study, the relationship between the corn particle size, measured as the geometric mean diameter (GMD), and thermoregulation was evaluated by determining the effect of the GMD on performance, egg quality, and physiological responses. Feed intake, eggshell quality (weight and thickness), rectal temperature (T R), respiratory rate (R R), and surface temperature (T S) were recorded in sixty 20-week-old naked neck laying hens that were fed corn of different particle sizes. Ambient temperature (T A) was also recorded during the trial. The GMD of corn particles was determined using a screens granulometer, resulting in sizes of 605, 1,030, and 2,280 µm. The analysis of variance (ANOVA) of a completely randomized design showed a significant effect (P < 0.05) of GMD on feed intake, shell weight, and shell thickness. The ANOVA performed by the least squares method showed a highly significant effect (P < 0.01) of GMD on T R and R R. T A, categorized into three classes (24.0-26, 26.1-28.9, and 29.0-31.0 °C), had a significant effect (P < 0.01) on T R and T S. The interaction between the GMD of corn particles and the T A classes was not statistically significant. Coarser corn particles cause an increase in the rectal temperature of naked neck hens, and these birds increase their respiratory rate to dissipate excess metabolic heat. This increase in the respiratory rate causes a decrease in the eggshell quality.

Shade evaluation of ceramic laminates according to different try-in materials.

The porcelain laminate replaces the visible portion of enamel with a ceramic, which is attached to the dental surface. To enhance cosmetic results, a preliminary color matching procedure is performed prior to cementing the veneers. This procedure can be performed using water, water-soluble gel, or try-in paste. The different shades of cement and try-in pastes are intended to obtain better color and esthetics of the final restoration. This study sought to evaluate the shade of ceramic veneers produced by different try-in materials. Forty bovine teeth and 40 ceramic discs (0.6 mm thick) were prepared. The samples were divided into 4 groups (n = 10). For Group 1 samples, no material was used between the tooth and the ceramic, Group 2 interposed samples with water, Group 3 used a water-soluble gel, and Group 4 used try-in paste (value 0). The color was measured with a spectrophotometer, obtaining L*, a*, and b* values to calculate the color difference (ΔE*). The data were subjected to normality tests and 1-way ANOVA. No significant statistical differences were found among the groups, indicating that the different try-in materials had similar effects on the color of the ceramic laminates.

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment.

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R S-W, W m(-2)), were recorded. The R S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R S-W remained below 500 W m(-2). The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m(-2), the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R S-W exceeded 700 W m(-2). The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R S-W were recorded (815 and 958 W m(-2), respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m(-2).

Influence of activation mode of resin cement on the shade of porcelain veneers.

PURPOSE: The aim of this study was to evaluate the influence of resin luting cement's activation mode in the final shade of porcelain veneers after accelerated artificial aging (AAA). MATERIALS AND METHODS: Porcelain veneers (IPS Empress Esthetic) were produced using a standardized shade (ET1) and thickness (0.6 mm). Twenty bovine teeth were collected, prepared, and divided into two groups: group I (n = 10)-light-cured group, only base paste was applied to the veneers; group II (n = 10)-dual-cured group, in which the same base paste used in group I and a transparent catalyst were proportionally mixed for 20 seconds and then applied to the veneers. The specimens were light-cured for 60 seconds each and were next subjected to AAA. They were submitted to color readings with a spectrophotometer in three instances: in the tooth surface (only the substrate), after the cementation and polymerization of the veneers, and after the AAA. The values of L*, a*, and b* were obtained and the total color change was calculated (∆E*). Values obtained were subjected to statistical analysis, with a significance of 0.05. RESULTS: There were no significant differences between dual- and light-cured modes considering ∆E*, L*, a*, and b* values obtained after aging (p > 0.05). Within the dual-cured mode there were no significant differences in ∆E*, L*, a*, and b* values (p > 0.05). CONCLUSION: No relevant differences were found between the two activation modes in color change. When submitted to aging, dual- and light-cured modes of the resin cement showed visually perceptible (∆E* > 1.0) color changes; however, within the threshold of clinical acceptance (∆E* > 3.3).

Daily variations in the thermoregulatory behaviors of naked neck broilers in an equatorial semi-arid environment.

The aim of this study was to evaluate the daily variations in the thermoregulatory behavior of 4- to 6-week-old naked neck broilers (Label Rouge) in an equatorial semi-arid environment. A total of 220 birds were monitored for 5 days starting at 0600 hours and ending at 1800 hours. The period of observation was divided into classes of hours (C H). The observed behaviors were as follows: feed and water intake, wing-spreading, sitting or lying, and beak-opening. A total of 14,300 behavioral data values were registered. In C H 2 (0900 hours to 1100 hours) and 3 (1200 hours to 1500 hours), the greatest average body surface temperature was recorded (34.67 ± 0.25 °C and 35.12 ± 0.22 °C, respectively). The C H had an effect on the exhibition of all behaviors with the exception of the water intake behavior. Feed intake was more frequent in C H 1 (0600 hours to 0800 hours) and 4 (1600 hours to 1800 hours). In C H 2 and 3, the highest frequency of sitting or lying behavior was observed. Beak-opening and wing-spreading behaviors occurred more frequently in C H 3 where the body surface temperature (35.12 ± 0.22 °C), radiant heat load (519.38 ± 2.22 W m(-2)), and enthalpy (82.74 ± 0.36 kJ kg(-1) of dry air) reached maximum recorded averages. Thus, it can be concluded that naked neck broilers adjust their behavior in response to daily variations in the thermal environment. Wing-spreading and beak-opening behaviors are important adaptive responses to the thermal challenges posed by the equatorial semi-arid environment.

Unilateral fusion of maxillary lateral incisor: diagnosis using cone beam computed tomography.

Objective. The objective of this paper is to report a dental fusion case focusing on clinical and radiographic features for the diagnosis. Method. To report a case of right maxillary lateral incisor fusion and a supernumerary tooth, the anatomy of the root canal and dental united portion were assessed by cone beam computed tomography (CBCT). Results. The clinical examination showed dental juxtaposition with the absence of interdental papilla and esthetic impairment in the right maxillary lateral incisor region. The periapical radiography did not provide enough information for the differential diagnosis due to the inherent limitations of this technique. CBCT confirmed the presence of tooth fusion. Conclusion. CBCT examination supports the diagnosis and provides both the identification of changes in tooth development and the visualization of their extent and limits.

Regional differences in the surface temperature of Naked Neck laying hens in a semi-arid environment.

The aim of this study was to evaluate the regional differences in the surface temperature of Naked Neck hens that were subjected to different temperatures in a semi-arid environment. The surface temperature was measured in four body regions (face, neck, legs and feathered area) of 60 Naked Neck hens. The following environmental variables were measured at the center of the shed: the black globe temperature (T G ), air temperature (T A ), wind speed (U) and relative humidity (R H ). The T A was divided into three classes: 1 (24.0-26.0 °C), 2 (26.1-28.9 °C) and 3 (29.0-31.0 °C). An analysis of variance was performed by the least squares method and a comparison of the means by the Tukey-Kramer test. The results showed a significant effect of T A class, the body region and the interaction between these two effects on the surface temperature. There was no significant difference between the T A classes for the face and neck. The legs and feathered area showed significant differences between the T A classes. Regarding the effect of body regions within each T A class, there was a significant difference among all regions in the three T A classes. In all T A classes the neck had the highest average followed by the face and legs. The feathered area showed the lowest average of the different T A classes. In conclusion, this study showed that there are regional differences in the surface temperature of Naked Neck hens, with the legs acting as thermal windows.

Effect of light source and solvent on the sorption and solubility of two dual-cured cements photocured through ceramic.

The purpose of this study was to verify the polymerization efficiency of two curing units through a ceramic barrier. Forty specimens apiece of two resin luting cements (AllCem and RelyX U100) were made in a stainless steel mold. The experimental group was photocured through a ceramic barrier, while the control group was photocured without a barrier. The specimens were stored in deionized water or 75% ethanol for 28 days and submitted to tests of sorption and solubility (ISO 4049:2000). Values obtained were subjected to ANOVA and Tukey multiple comparison tests (P < 0.05). RelyX U100 suffered more sorption and solubility than AllCem. The light sources did not influence sorption and solubility values, except for the specimens of RelyX U100 that were photocured with an LED unit through ceramic and stored in ethanol; these specimens demonstrated higher values than those photocured using a halogen lamp.

How light sources and distance of the light tip influence water sorption, solubility, and biaxial flexural strength of a composite resin.

This study evaluated the water sorption (WS), solubility (SL), and biaxial flexural strength (BFS) of a resin composite based on different polymerization units, storage permeants (distilled water and 75% ethanol), and distances between the light's tip and the composite resin. Using a stainless steel mold, 80 specimens were made and separated in two independent groups, according to the duration of storage (7 days or 60 days). The specimens were photocured using either a QTH or LED light (both used at 600 mW/cm2 for 40 seconds), with the light's tip guide either 0 mm or 2 mm from the surface of the resin. In general, the 75% ethanol produced higher WS and SL values but lower BFS values compared to water. Both distances influenced the WS and SL values, especially when 75% ethanol was used (p < 0.05), although neither distance affected BFS values (p > 0.05). For nearly all groups, the WS, SL, and BFS in different solvents and at different distances for photocuring of the tested resin were not affected by the curing light used.

Influence of pulse-delay curing on sorption and solubility of a composite resin.

The purpose of this study was to evaluate the sorption and solubility of a composite resin (TPH(3); Dentsply) cured with halogen light due to different storage media and curing modes. The methodology was based on the ISO 4049 standard. Two independent groups were established according to the storage time (7 days-G1; 60 days-G2). A stainless steel mould (2 mm x 8 mm Ø) was used. The selected curing modes were: I (Conventional - C): 40s - 600 mW/cm(2); II (Pulse I - PD): 3 s - 200 mW/cm(2) + 2 min (delay) + 39 s - 600 mW/cm(2); III (Pulse II): 10 s - 200 mW/cm(2) + 2 min (delay) + 37 s - 600 mW/cm(2); IV (Pulse III): 3 s- 600 mW/cm(2) + 2 min (delay) + 37 s -600 mW/cm(2). The media used were: distilled water, 75% ethanol and 100% chlorophorm. Five repetitions were made for each group. The specimens were placed in a desiccator at 37 masculineC for 24 h and, after that, at 23 masculineC for 1 h to be weighed until a constant mass (m1) was obtained. The discs were immersed separately into the 3 media for 7 days (G1) and 60 days (G2), and thereafter reweighed (m2). The reconditioning in the desiccator was done until a constant mass (m3) was obtained. Sorption and solubility were calculated and the data of G1 and the sorption data of G2 were subjected to two-way ANOVA and Tukey's tests (p=0.05). The solubility data of G2 were analyzed by Kruskal-Wallis test (p=0.05). For G1 and G2, no statistically significant differences were found in sorption among curing techniques (p>0.05). The solubility values were negative, which means that there was mass gain. Regarding the storage media, in G2 chlorophorm had the highest sorption values. It may be concluded that the curing modes (C and PD I, II and III) did not affect the sorption of the tested composite resin. However, different storage media influenced sorption behavior. The solubility test demonstrated negative data, masking the real solubility.

Evaluation of internal adaptation of Class V resin composite restorations using three techniques of polymerization.

OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M) and 3M Filtek Z250/ Single Bond (H) in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm(2)); Group 2 - Soft-start (20 s - 200 mW/cm(2) , 40 s - 600 mW/cm(2)); Group 3 - Pulse Activation (3 s - 200 mW/cm(2), 3-min hiatus, 57 s - 600 mW/cm(2)). Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls). RESULTS: The mean scores of the groups were (+/-SD) were: G1M-3.0 (+/- 0.0); G2M-2.43 (+/- 0.8); G3M- 1.71 (+/- 0.9); G1H- 2.14 (+/- 1.2); G2H- 2.00 (+/- 0.8); G3H- 1.67 (+/- 1.1). Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05) was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.