Influence of surface sealing on color stability and roughness of composite submitted to ultraviolet-accelerated aging.

AIM: In the present study, we evaluated the influence of surface sealing on color stability and surface roughness of a composite resin after accelerated artificial aging. METHODS: Thirty-two specimens of a composite were prepared. After 24 h, the specimens were polished and divided into four groups (n = 8), according to the surface sealant used, including the control, which had no sealant application. Baseline color was measured according to the CIELab system using a reflection spectrophotometer. Surface roughness was determined using a profilometer with a cut-off of 0.25 mm. After these tests, specimens were aged for 252 h in an ultraviolet (UV)-accelerated aging chamber. Color stability was determined by difference between coordinates obtained before and after the aging procedure. Data of color change and roughness were evaluated by anova and Fisher's exact test (α = 0.05). RESULTS: The results showed that the unsealed group had the highest color change compared to other groups (P = 0.0289), and there was no significant difference between groups sealed with surface sealant (P > 0.05). The artificial aging caused an increase in roughness values independent of the experimental group studied (P = 0.0015). CONCLUSION: The sealed composites showed lower color change after UV aging, but all groups showed clinically-acceptable color change, and only liquid polish decreased roughness.

Consideraciones metodológicas sobre el estudio de la adaptación del cemento sellador a las paredes del conducto: comparación entre el microscopio electrónico de barrido y el confocal láser / Methodological considerations on the study of endodontic sealer adaptation to root canal walls: comparison between scanning electronic and laser confocal microscopes

Objetivo: Evaluar la correlación entre las observaciones con el microscopio electrónico de barrido (MEB) y con el microscopio confocal láser (MCL) para el estudio de la adaptación a las paredes del conducto de TopSeal. Material y métodos: Diez dientes unirradiculares fueron instrumentados con el sistema de limas rotatorias MTwo hasta el 35/.04. Se irrigó con 5 ml de NaOCl (5,25%) entre limas y con 5 ml de EDTA (17%) como irrigante final. La obturación se realizó con condensación lateral utilizando conos de gutapercha y cemento TopSeal marcado con un fluorocromo. Se obtuvieron secciones transversales a 3, 5 y 8 milímetros del ápice, que fueron analizadas con MCL y luego metalizadas y observadas con MEB. Se estableció el grado de adaptación al perímetro del conducto en cada sección con ambos procedimientos. En el análisis estadístico se utilizaron el coeficiente de correlación de Pearson para la evaluación de la interfase cemento-dentina entre ambos métodos y el ANOVA para el análisis de la penetración intratubular del cemento evaluada con MCL. Resultados: El coeficiente de correlación de Pearson fue de 0,75 (p = 0,001) para los porcentajes medios de adaptación. Medias: MCL 71,40 y MEB 83,67. Los coeficientes para los tercios apical, medio y coronal fueron 0,940, 0,772 y 0,877 respectivamente, en todos los casos significativos. Respecto a la penetración del cemento sellador, no se encontraron diferencias significativas en los niveles estudiados. Conclusiones: Ambas técnicas microscópicas son complementarias, mientras que el MEB proporciona mayor seguridad en el estudio de la interfase, el MCL permite analizar la penetración intratubular del material

Aim: To compare two different microscopic techniques (SEM and CLSM) in studying filling materials adaptation to canal walls. Material and Methods: Ten sound extracted single-rooted teeth were selected, instrumented and filled with gutta-percha and TopSeal using lateral condensation technique. Following root filling, teeth were sectioned transversally at 3, 5 and 8 mm from the apex and analyzed using Confocal Laser Scanning Microscope and Scanning Electronic Microscope. Percentage of root canal perimeter with sealer penetration to the dentinal tubules and depth of penetration were compared between groups and statistically analyzed using a Pearson correlation analysis (p=0.001) and ANOVA test for intratubular penetration. Pearson’s correlation coefficient for the whole sample was 0.75 (p=0.001). Results: When comparing sealer adaptation to dentinal walls between thirds, apical medium and coronal, mean values were statistically significant: 0.940, 0.772 and 0.877 respectively. For intratubular penetration no significant difference between root canal thirds was found. Conclusions: Both techniques are complementary in the study of endodontic filling materials performance inside root Canals

Can Increasing the Manufacturer's Recommended Shortest Curing Time of High-intensity Light-emitting Diodes Adequately Cure Sealants?

PURPOSE: To investigate sealant depth of cure after increasing the curing times of high-intensity light-emitting diode units (LEDs). METHODS: Three sealants (opaque-unfilled, opaque-filled, and clear-filled) were light cured in a covered-slot mold with: (a) three LEDs (VALO, SmartLite, Fusion) for six to 15 seconds; and (b) a quartz-tungsten halogen (QTH) light for 40 seconds as a control (N=10). Twenty-four hours after light curing, microhardness was measured at the sealant surface and through the depth at 0.5 mm increments. Results were analyzed via analysis of variance followed by the Student-Newman-Keuls test (significance level 0.05). RESULTS: The opaque-filled and clear-filled sealants cured with VALO for six or nine seconds had hardness values that were statistically equivalent to or better than the QTH to a depth of 1.5 mm. Using Fusion for 10 seconds (exposure limit) did not adequately cure the three sealants beyond one mm. SmartLite at 15 seconds (maximum exposure period without overheating) did not adequately cure the sealants beyond 0.5 mm. CONCLUSIONS: Among the tested high-intensity LEDs, only VALO at double or triple the manufacturers' shortest curing time (six or nine seconds) provided adequate curing of opaque-filled and clear-filled sealants at 1.5 mm depth compared to the 40-second QTH light.

Influence of light-curing mode on the cytotoxicity of resin-based surface sealants.

BACKGROUND: Surface sealants have been successfully used in the prevention of erosive tooth wear. However, when multiple tooth surfaces should be sealed, the light-curing procedure is very time-consuming. Therefore, the aim of this study was to investigate whether reduced light-curing time (while maintaining similar energy density) has an influence on resin-based surface sealant cytotoxicity. METHODS: Bovine dentine discs were treated as follows: group 1: untreated, groups 2-5: Seal&Protect and groups 6-9: experimental sealer. Groups 2 and 6 were light-cured (VALO LED light-curing device) for 40 s (1000 mW/cm2), groups 3 and 7 for 10 s (1000 mW/cm2), groups 4 and 8 for 7 s (1400 mW/cm2) and groups 5 and 9 for 3 s (3200 mW/cm2). Later, materials were extracted in culture medium for 24 h, and released lactate dehydrogenase (LDH) activity as a measure of cytotoxicity was determined photometrically after cells (dental pulp cells and gingival fibroblasts) were exposed to the extracts for 24 h. Three independent experiments, for both sample preparation and cytotoxicity testing, were performed. RESULTS: Overall, lowest cytotoxicity was observed for the unsealed control group. No significant influence of light-curing settings on the cytotoxicity was observed (p = 0.537 and 0.838 for pulp cells and gingival fibroblasts, respectively). No significant difference in the cytotoxicity of the two sealants was observed after light-curing with same light-curing settings (group 2 vs. 6, 3 vs. 7, 4 vs. 8 and 5 vs. 9: p > 0.05, respectively). CONCLUSIONS: Shortening the light-curing time, while maintaining constant energy density, resulted in no higher cytotoxicity of the investigated sealants.

Effect of acid etching and different Er:YAG laser procedures on microleakage of three different fissure sealants in primary teeth after aging.

The purpose of this study was to evaluate the effects of different surface conditioning procedures on microleakage and unfilled area proportions of three fissure sealants(Aegis, Helioseal and Helioseal F) in primary molar teeth. One hundred and fifty teeth were randomly divided into five main groups according to surface conditioning procedures. Main groups were; acid-etching(Group A); laser 3.75 W(Group B) and 5 W(Group D); acid-etching combined with laser 3.75 W(Group C) and 5 W(Group E). Samples were aged by thermocycling and water bath. Afterwards, they were immersed in basic fuchsin solution for 24 h and bucco-lingual sections were obtained from each tooth. Digital images were taken using a stereo-microscope and the microleakage and unfilled area proportions were assessed by using a software system. Consequently, Aegis FS containing amorphous calcium phosphate was found to exhibit the lowest microleakage in all surface conditioning procedures. Unfilled areas were not detected in Groups C and E of all FSs.

Comparison of halogen versus LED light-cured temporary endodontic filling materials for sealing.

AIM: The purpose of this study was to compare the sealing ability of the three light-cured temporary restorative materials curing with two different light curing devices; halogen and LED. METHODS: After the preparation of standard endodontic access cavities, the canal systems were instrumented by using a step-back technique irrigated with sodium hypochlorite and EDTA. Light-cured temporary restorative materials; First fill, Bioplic, and Diatemp were applied and polymerized with either of the LED or Halogen light-curing devices. The specimens were immersed in 2% methylene blue solution for four days in an incubator for the leakage assessment. RESULTS: The first fill presented the least microleakage values for both the LED (2.54±0.53) and halogen (2.84±0.48) treated groups whereas; Diatemp presented the highest microleakage values for both the LED (2.83±0.59) and halogen (3.28±0.56) groups. The leakage values of all light-cured temporary filling materials for the LED-treated groups were lower than the halogen treated ones. However, there were statistically no significant differences among the three groups (P>0.05). CONCLUSION: It is concluded that light curing temporary filling materials can achieve a good and comparable sealing capacity when cured by both LED and halogen LCUs.

Effect of artificial aging on the bond durability of fissure sealants.

PURPOSE: To evaluate the effect of artificial aging on the bond durability of fissure sealants in vitro. MATERIALS AND METHODS: Twenty bovine incisors received 4 different sealant treatments and were divided into four groups: 1. Ultraseal XT plus (UX); 2. Enamel Loc (EL); 3. 35% phosphoric acid plus Enamel Loc (PEL); 4. Adper Prompt L-Pop plus Clinpro (PPC). Beam-shaped specimens were prepared and randomly divided into three subgroups. One subgroup underwent the microtensile bond strength (µTBS) test after 24-h storage in 37°C water. The other two subgroups were also subjected to the microtensile bond strength test after 5000 and 10,000 thermal cycles, respectively. Another twelve intact human third molars were sealed using 1 of 3 methods and were divided into 3 groups of 4 each: 1. Ultraseal XT plus; 2. Adper Prompt L-Pop plus Clinpro; and 3. Enamel Loc. Two specimens from each group were immersed in a 50% silver nitrate solution for 24 h, followed by exposure to fluorescent light for 8 h, before being scanned in a micro-CT (microcomputer tomography) machine. The other two were handled in the same way after undergoing 10,000 thermal cycles. The CT images obtained were evaluated. RESULTS: All samples from the EL group were broken during preparation, so no µTBS results were available. After 5000 thermal cycles, the bond strengths of the three other groups (UX, PEL, PPC) decreased significantly (p < 0.05). Longer thermocycling (10,000 cycles) resulted in more decreases in µTBS for group PEL and PPC, while the strength of the UX group remained relatively unchanged. After thermocycling, considerable silver penetration could be seen at the sealant/enamel interface of the EL group in micro-CT images. CONCLUSIONS: The etch-and-rinse procedure for sealant application promotes higher bond strength under artificial aging. Micro-CT, a nondestructive analytical tool, may be used to evaluate the sealant/enamel interface effectively.

Impact of adhesive and photoactivation method on sealant integrity and polymer network formation

We evaluated the influence of photoactivation method and hydrophobic resin (HR) application on the marginal and internal adaptation, hardness (KHN), and crosslink density (CLD) of a resin-based fissure sealant. Model fissures were created in bovine enamel fragments (n = 10) and sealed using one of the following protocols: no adhesive system + photoactivation of the sealant using continuous light (CL), no adhesive system + photoactivation of the sealant using the soft-start method (SS), HR + CL, or HR + SS. Marginal and internal gaps and KHN were assessed after storage in water for 24 h. The CLD was indirectly assessed by repeating the KHN measurement after 24 h of immersion in 100% ethanol. There was no difference among the samples with regard to marginal or internal adaptation. The KHN and CLD were similar for samples cured using either photoactivation method. Use of a hydrophobic resin prior to placement of fissure sealants and curing the sealant using the soft-start method may not provide any positive influence on integrity or crosslink density.

Impact of adhesive and photoactivation method on sealant integrity and polymer network formation.

We evaluated the influence of photoactivation method and hydrophobic resin (HR) application on the marginal and internal adaptation, hardness (KHN), and crosslink density (CLD) of a resin-based fissure sealant. Model fissures were created in bovine enamel fragments (n = 10) and sealed using one of the following protocols: no adhesive system + photoactivation of the sealant using continuous light (CL), no adhesive system + photoactivation of the sealant using the soft-start method (SS), HR + CL, or HR + SS. Marginal and internal gaps and KHN were assessed after storage in water for 24 h. The CLD was indirectly assessed by repeating the KHN measurement after 24 h of immersion in 100% ethanol. There was no difference among the samples with regard to marginal or internal adaptation. The KHN and CLD were similar for samples cured using either photoactivation method. Use of a hydrophobic resin prior to placement of fissure sealants and curing the sealant using the soft-start method may not provide any positive influence on integrity or crosslink density.

Removal of organic debris with Er:YAG laser irradiation and microleakage of fissures sealants in vitro.

The current study was conducted to improve fissure sealing by pre-treatment with Er:YAG laser irradiation in order to remove organic debris. The surface morphology, surface roughness of fissure cavities, and the degree of microleakage after laser treatment were compared with those after bristle brush treatment in vitro. Sixty extracted human teeth were used in this study. The teeth were randomly divided into two groups of 30 each. Artificial fissures were prepared in all teeth into which artificial organic debris was placed. The debris in 30 teeth of one group was removed by means of Er:YAG laser system and the remaining 30 teeth were cleaned using a bristle brush with prophylaxis paste. Surface morphology and surface roughness of were analyzed in ten samples from each group by color laser three-dimensional (3D) microscopy and by scanning electron microscopic examination. The remaining samples were then filled with sealant and subjected to a microleakage test under thermocycling. Statistical analysis was performed using the Mann-Whitney U test; a value of p < 0.05 was considered significant. Morphologically, most of the debris was removed by Er:YAG laser treatment, whereas some fissures were not cleaned by bristle brush. However, microleakage test of both laser and etched brush methods showed similar results. Laser technique might facilitate good adaptation of resin sealant to enamel, because of an increase in surface roughness and favorable surface characteristics.

Tensile bond strength of sealants following Er:YAG laser etching compared to acid etching in permanent teeth.

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and pretreated as follows: (1) 37% phosphoric acid; (2) Er:YAG laser (1.5 ml/min water spray, 100 mJ energy output, 10 Hz frequency, focal distance 17 mm); (3) Er:YAG laser + 37% phosphoric acid. The treated surfaces were isolated by double adhesive Sellotape and after insertion of a split Teflon matrix at an isolated site, sealant was applied. The specimens were thermocycled and stored at 37°C in distilled water for 72 h, then subjected to a tensile bond strength test (50 kgf at 0.5 mm/min). The mean tensile bond strengths (± SD, in megapascals) were: 18.51 ± 5.68 in group 1, 8.06 ± 2.69 in group 2, and 17.33 ± 5.04 in group 3. Data were submitted to analysis of variance and the Tukey test. No significant difference were found between groups 1 (37% phosphoric acid) and group 3 (Er:YAG laser + 37% phosphoric acid) but treatment with the Er:YAG laser alone (group 2) resulted in significantly lower tensile bond strength than seen in the other groups. In this setting, the Er:YAG laser prepared the enamel surface for sealing but did not eliminate the need for acid etching before sealant application.

Effect of light curing methods on microleakage and microhardness of different resin sealants.

PURPOSE: This study's purpose was to evaluate the effect of light curing methods on the microleakage and microhardness of sealants. METHODS: The Elipar Free Light 2 light emitting diode (LED) with 10- and 20-second curing times, and the Elipar 2500 halogen light with a 20-second curing time were compared. Four different sealants were used: (1) Delton Clear; (2) Delton Opaque; (3) UltraSeal XT Clear; and (4) UltraSeal XT Opaque. Specimens were fabricated in a silicone mold (2-mm thick) and cured. Knoop hardness was measured at the bottom and top surfaces. For the microleakage evaluation, 120 human molars were divided into 12 groups and sealed with the sealants and curing methods, as stated previously. The teeth were thermocycled and immersed in 2% methylene blue for 24 hours. Each tooth was sectioned and examined for dye penetration. RESULTS: There were no statistically significant differences in the microleakage of sealants polymerized by either the halogen or LED curing methods. The microhardness of sealants varied according to the type of material and curing method. CONCLUSIONS: A 10-second polymerization time with light emitting diodes was not sufficient to cure the 2-mm-thick opaque or high filler loaded sealants. Decreasing the curing time, however, had no effect on the microleakage of the sealants.

Impact of extended radiant exposure time on polymerization depth of fluoride-containing fissure sealer materials.

Physical properties such as surface hardness of dental materials are directly linked to their clinical behavior. The aim of this study was to investigate the influence of extended curing time on the polymerization depth offluoride-containing materials used as pit and fissure sealants. Conventional and extended exposure times (20 and 60 seconds) were used to photoactivate a gold-standard pit and fissure sealant (Fluroshield, Dentsply) and a flowable composite (PermaFlo, Ultradent). Twenty square-shaped samples (n=5) were prepared using a LED device (Bluephase 16i, Ivoclar). The Knoop Hardness Number (KHN) was calculated for the top and bottom surface of each sample 24 hours after polymerization. Bottom/top hardness ratio (B/T KHN) was than calculated. Averages were analyzed by two-way ANOVA and Tukey test (alpha=0.05). The flowable composite had higher KHN than conventional pit and fissure sealant for all experimental conditions (p<0.05). The 60-second photoactivation time increased KHN at the bottom surface and B/T KHN only of composite specimens. The flowable composite had better physical properties than the pit and fissure sealant, and they were improved by extended curing time.

In vitro evaluation of marginal leakage using invasive and noninvasive technique of light cure glass ionomer and flowable polyacid modified composite resin used as pit and fissure sealant.

AIM: This study compared the microleakage of light cure glass ionomer and flowable compomer as pit and fissure sealant, with and without tooth preparation. MATERIALS AND METHODS: One hundred premolars that were extracted for orthodontic purpose were used. After adequate storage and surface debridement, the teeth were randomly divided into four groups. In Group I and III, the occlusal surfaces were left intact, while in Group II and Group IV, tooth surfaces were prepared. Teeth in Group I and Group II were sealed with Light cure glass ionomer, whereas flowable compomer was used to seal teeth in Group III and IV. The sealed teeth were then immersed in dye. Subsequently, buccolingual sections were made and each section was examined under stereomicroscope for microleakage followed by scoring. RESULTS: In group I, microleakage score ranged from 2 to 4 with mean of 3.64 (±0.757), while in group II the range was observed to be 1-4 with mean of 2.88 (±1.236). Group III recorded a range of 0-4 with the mean of 2.20 (±1.443) while 0-2 and 0.60 (±0.707) being the range and mean observed, respectively, for group IV. CONCLUSION: Flowable compomer placed after tooth preparation showed better penetration and less marginal leakage than the light cure glass ionomer.

Effect of irradiation times on the polymerization depth of contemporary fissure sealants with different opacities.

The aim of this study was to evaluate the depth of curing of 10 contemporary blue light-activated dental flowable materials at several opacities, influenced by different irradiation times using FT-IR spectroscopy. Fifty-five specimens (n = 5) with a 5-mm diameter and 1-mm thickness of translucent (Opallis Flow T), yellowed (Master Flow A2; Opallis Flow A2; Natural Flow A2; Fluroshield Yellowed), and opaque materials (Master Flow OA2; Natural Flow O; Opallis Flow OA3.5; Opallis Flow OP; Fluroshield White) were obtained at six curing times (10s, 20s, 30s, 40s, 50s, and 60s) using a high-intensity LED (Coltolux, Coltène/Whaledent). The degree of conversion (DC) (%) was obtained using the Nexus 470 FTIR Spectrometer (Nicolet Instruments, USA). The FTIR-ATR spectra for uncured and cured samples were analyzed using a ZnSe crystal. The top and bottom surfaces of the cured specimens were analyzed to obtain the depth of curing. Two-way ANOVA was used to analyze the data. The highest curing depth was obtained by Natural Flow OA2, while the lowest was shown by Master Flow OA2. The shortest curing time generated similar depths of cure in comparison with the most extensive for Opallis Flow A2 and Fluroshield Yellowed. Therefore, depth of curing, influenced by the irradiation time, was dependent on the materials. Using the Natural Flow OA2 opaque sealant and the 10-s curing time for Opallis Flow A2 and Fluroshield Yellowed may represent alternative approaches to sealing tooth fissures.

Effect of irradiation times on the polymerization depth of contemporary fissure sealants with different opacities

The aim of this study was to evaluate the depth of curing of 10 contemporary blue light-activated dental flowable materials at several opacities, influenced by different irradiation times using FT-IR spectroscopy. Fifty-five specimens (n = 5) with a 5-mm diameter and 1-mm thickness of translucent (Opallis Flow T), yellowed (Master Flow A2; Opallis Flow A2; Natural Flow A2; Fluroshield Yellowed), and opaque materials (Master Flow OA2; Natural Flow O; Opallis Flow OA3.5; Opallis Flow OP; Fluroshield White) were obtained at six curing times (10s, 20s, 30s, 40s, 50s, and 60s) using a high-intensity LED (Coltolux, Coltène/Whaledent). The degree of conversion (DC) ( percent) was obtained using the Nexus 470 FTIR Spectrometer (Nicolet Instruments, USA). The FTIR-ATR spectra for uncured and cured samples were analyzed using a ZnSe crystal. The top and bottom surfaces of the cured specimens were analyzed to obtain the depth of curing. Two-way ANOVA was used to analyze the data. The highest curing depth was obtained by Natural Flow OA2, while the lowest was shown by Master Flow OA2. The shortest curing time generated similar depths of cure in comparison with the most extensive for Opallis Flow A2 and Fluroshield Yellowed. Therefore, depth of curing, influenced by the irradiation time, was dependent on the materials. Using the Natural Flow OA2 opaque sealant and the 10-s curing time for Opallis Flow A2 and Fluroshield Yellowed may represent alternative approaches to sealing tooth fissures.

Light transmittance characteristics and refractive indices of light-activated pit and fissure sealants.

We examined the light transmittance characteristics and refractive indices of light-activated pit and fissure sealants. Five commercial pit and fissure sealants and human enamel were studied, along with the CIE L*a*b* color values of the materials and enamel. The light transmittance spectra of the pit and fissure sealants showed a similar trend to the enamel, especially at wavelengths below 530 nm. The average light transmittance values from 400 to 500 nm of the materials at 0.5-mm-thick ranged from 10.0% to 40.4%. The refractive indices at 589.3 nm ranged from 1.504 to 1.546, and were approximately 4-8% lower than that of enamel. The measurements for the surface hardness of materials indicate that the light-attenuating effect of enamel and the material itself reduced the polymerization efficiency of the material. For all materials, chromatic a* showed negative and b* showed positive values, as did enamel. Significant differences in light transmittance characteristics and refractive indices between the materials and enamel may affect color matching between them.

A comparative study to evaluate the effect of fluoride releasing sealant cured by visible light, argon lasers, and light emitting diode curing units: an in vitro study.

In Pediatric Dentistry, the use of pit and fissure sealant is one of the essential forms of prevention. Pit and fissure caries may be substantially decreased by obliteration of these developmental defects in occlusal, buccal and lingual surfaces with resin based dental sealants. Visible light-curing units, or LCUs, are an integral part of modern adhesive dentistry" They are used to cure resin based composite restoration materials, resin modified glass-ionomer and pit and fissure sealants, as well as to bond orthodontic teeth. Most recently, the argon laser has been approved for initiating the setting reaction with visible light cured-resins. Argon curing of resin materials has been show to enhance the physical properties and degree of polymerization of the resin, while reducing the polymerization time by 75 percent. The study is undertaken considering the inadequate research reports of regarding the comparison of curing ability using argon laser. LEDs and visible light as well as the resistant towards caries activity of the preventive fluoride releasing pit and fissure sealant cured by above mentioned curing units.

Effect of gamma irradiation on fluoride release and antibacterial activity of resin dental materials.

This study evaluated the effect of gamma irradiation on fluoride release and antibacterial activity of FluroShield (FS) and Clearfil Protect Bond (CPB). Four groups were formed: G1-FS + gamma; G2-FS without gamma; G3-CPB + gamma; G4-CPB without gamma. For fluoride release analysis, 12 disks of each material were prepared and covered with nail polish, except for one side (50.4 mm(2) area). G1 and G3 were sterilized with a 14.5 KGy dose at 27 degrees C for 24 h, while G2 and G4 (controls) were not sterilized and were maintained under the same time and temperature conditions. Fluoride release measurements were made in duplicate (n=6) by an ion specific electrode. The antibacterial activity of the CPB and FS against Streptococcus mutans after gamma sterilization was evaluated by the agar-disc diffusion method. The diameter of the zones of microbial growth inhibition was recorded after 48 h. Data were analyzed statistically by ANOVA and Tukey's test (alpha=5%). Gamma sterilization decreased the fluoride release of FS by approximately 50%, while CPB was not affected. There was no statistically significant difference (p>0.05) in the antibacterial effect of CPB between gamma and non-gamma sterilization groups. FS presented no antibacterial activity. Gamma irradiation decreased the fluoride release of FS, but did not affect the antibacterial activity of the studied materials.