Unfilled Sealant Research Articles

Microleakage Assessment of Repaired Pit and Fissure Sealants Using Different Surface Treatment – An In vitro Study

ABSTRACT Aim: In this in vitro study, the microleakage evaluation of repaired pit and fissure sealants with various surface treatments was compared. Study Design: The study included 120 extracted human third molars. The teeth were divided into two groups of 60 each. Group 1 was sealed with Clinpro™ unfilled sealant, while group 2 was sealed with Grandioseal nanofilled sealants. After curing, half of the polymerized sealant were removed. Both groups were divided further into two subgroups of 30 teeth each, with repair techniques using either Adper Easy One or Futura Bond. Three sections were obtained from each tooth resulting 6 surfaces per tooth to be examined and the sections of all four groups were scored for microleakage. Results: Conventional acid etching was found to be superior to self-etch adhesive technique. Conclusion: Microleakage was found to be greater with Grandio seal compared to Clinpro.

Physicomechanical Properties of Resin-Based Pit and Fissure Sealants Reinforced with Rice Husk Derived Nano Silica and Nanohydroxyapatite

Resin-based pit fissure sealants (RBS) are used to prevent occlusal caries in children. The success of RBS in preventing dental caries is largely influenced by its retention on the tooth surface, which is also affected by its physicomechanical properties. The physicomechanical properties of RBS can be enhanced through the addition of fillers. With the advent of nanofillers, the physicomechanical properties were improved without altering RBS flowability. The present study developed an RBS with a 70 wt% resin matrix and 30 wt% nanofillers. The resin matrix consisted of urethane dimethacrylate (55 wt%), triethylene glycol dimethacrylate (45 wt%), camphoroquinone (0.3 wt%), and 2-(dimethylamino) ethyl methacrylate (0.7 wt%). Silane-treated rice husk-derived nanosilica (20 wt%) and nanohydroxyapatite (10 wt%) were added as fillers. Clinpro, Fissurit FX, and an unfilled sealant were controls. All RBS were tested for surface roughness, Vickers hardness, flexural strength, and flowability. Statistical analysis with oneway ANOVA revealed significant differences between groups in surface roughness, hardness, flowability (p < 0.001), flexural strength, and flexural modulus (p < 0.05). Experimental sealants had higher flexural strength (78 MPa) and flow distance (29.05+1.16 mm) than commercial controls. However, the surface roughness of experimental sealants (0.25+0.08 µm) was higher than Clinpro (0.087+0.027 µm) but lesser than Fissurit FX (0.35+0.19 µm). The Vickers hardness of experimental sealants (23+1.63 VHN) was less than Fissurit FX (28.80+1.69 VHN) but higher than Clinpro (21.74+1.68 VHN). This novel RBS had physicomechanical properties comparable to commercial sealants. The use of nanosilica from rice husk makes this pit and fissure sealer sustainable and environmentally friendly in dentistry.

Microleakage Assessment of Different Preparation Techniques and Pit and Fissure Sealants in Permanent Molars.

This study aimed to evaluate the predisposition of microleakage in permanent molar teeth following different preparation techniques for pits and fissure sealants. In this cross-sectional analytical study, a dye penetration method was employed to evaluate microleakage in dental restorations. A total of 104 extracted molars were randomly assigned into two groups and further subdivided into two subgroups based on a class of sealant (filled/unfilled resin) containing 26 teeth each. Teeth in one group were prepared by a conventional method using pumice and acid etching with 37% phosphoric acid, and teeth in the other group were prepared with a 1/4-round carbide bur in a low-speed handpiece and then acid etched. In each group, 26 teeth were sealed with a filled sealant, and 26 teeth with an unfilled sealant. The chi-square test was used for the comparison of microleakage between the groups. Unfilled sealants prepared with bur preparation showed the lowest degree of microleakage. The greater number of teeth (17) showed no microleakage in the group of teeth prepared using the bur preparation technique. Furthermore, in dye penetration analysis, the subgroup of teeth that were filled with unfilled sealants showed a greater number of teeth (57.6%), with zero penetration, and the dye penetration scores were statistically significant among the groups with different preparation techniques (p=0.002). Teeth whose pits and fissures were prepared through 1/4 carbide bur and filled with unfilled pits and fissure sealants show less microleakage than those prepared with the conventional method and filled with filled sealants. Therefore, the choice of surface preparation technique for pit and fissure sealants can influence the effectiveness of the sealant in preventing microleakage.

Comparative Evaluation of Penetrative and Adaptive Properties of Unfilled and Filled Resin-Based Sealants When Placed using Conventional acid Etching, Lasing, and Fissurotomy Bur Technique of Enamel Preparation: An in vitro Scanning Electron Microscope Study.

There is a confusion regarding selection of unfilled or filled sealant and method of enamel preparation before sealant application. This study was carried out to compare three techniques of enamel preparation using both unfilled and filled type of sealants. The objective of the study is to assess the penetrative and adaptive ability of filled and unfilled sealants in three techniques of enamel fissure preparations. Total 36 extracted teeth were divided into 3 groups, each containing 12 samples. The samples of Group A were prepared by conventional acid etching with 37% phosphoric acid, and the Group B was subjected to Er: YAG lasing, while in Group C, fissurotomy followed by acid etching was done. The sealant placement was carried out using split tooth design in all the samples. Assessment of penetration and adaptation was done under scanning electron microscope using the scoring criteria adopted by Kane B et al. and Dukic W et al. Group A and Group C showed better adaptation than Group B. Statistically, no significant difference was observed in the penetration property among three techniques. Similarly, the unfilled and filled sealant showed statistically nonsignificant results for the penetration and adaptation comparison. Irrespective of the sealant material selected, the conventional method of acid etching alone or in conjunction with fissurotomy bur for better retentiveness seems to be an acceptable choice of treatment modality. The study will help the clinicians to choose the sealant material and technique of enamel preparation.

Retention and caries-preventive effect of four different sealant materials: A 2-year prospective split-mouth study.

The aim of this observational split-mouth study was to compare the retention and caries protective effect of four different sealant materials in children aged 6-13years during a 2-year follow-up period. Eighty children were included in this study, which was conducted in Blato (Korčula island), Croatia. Each participant received at least two different sealant materials on caries-free permanent molars in two different quadrants. Sealant materials (M1 - glass-ionomer cement; M2, M4 - resin-based filled sealants; M3 - resin-based unfilled sealant) were delivered in a random order. The results of this study showed that M2 (30 teeth, 46.2%) and M4 (27 teeth, 46.6%) showed statistically significantly higher number of teeth with total retention after 2-year follow-up period, in comparison with M1 (10 teeth, 19.2%) or M3 (12 teeth, 20.7%) (p<.001). There was no statistically significant difference in caries occurrence between different groups in which the sealant material was totally retained. According to the results of this study, filled resin-based sealant materials showed better retention during the 2-year follow-up period while both resin-based and glass-ionomer sealants demonstrated protection against dental caries if totally retained on the occlusal surface.

Comparison of the Success Rate of Filled and Unfilled Resin-Based Fissure Sealants: A Systematic Review and Meta-Analysis.

Objectives: Incorporation of fillers might improve the physical properties of sealants. This systematic review and meta-analysis evaluated the retention and caries development rate of filled and unfilled fissure sealants. Materials and Methods: This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. The PubMed, Scopus, Embase, Cochrane Database of Systematic Reviews, and ISI Web of Knowledge were searched until October 24, 2019. The risk of bias (ROB) was assessed for the included studies based on the Cochrane collaboration common scheme for bias, and the meta-analysis was performed through a random effects model. Results: The search resulted in 6,336 unrepeated relevant studies. After the title, abstract and full-text screening, 19 studies with 26 comparing groups were finally included in this systematic review and meta-analysis. According to the included studies, both retention rate and caries development in filled and unfilled resin-based sealants did not significantly differ within 2 years of follow-up. Conclusion: Since there was no significant difference in the retention rate and caries development between filled and unfilled sealants, it seems that the final decision should be made uniquely for each patient according to the type of fissure, patient’s age, habits, etc.

Toothbrush-Dentifrice Abrasion of Dental Sealants: An In Vitro Study

Objective This study sought to investigate the toothbrush-dentifrice abrasion of dental sealants. Materials and Methods Weight loss (∆W) and depth loss (∆D) were used as abrasion indicators. Sealant samples from nine products were soaked in dentifrice slurry and abraded by using a toothbrushing machine with a brushing force of 300 g. The mean percentages of ∆W and mean values of ∆D after 24,000 and 48,000 strokes of brushing were compared by using paired t -test. A comparison of these mean values among sealant products was performed by using one-way ANOVA and multiple comparison analysis (Scheffe's test). Results Abrasive wear was observed in all sealants. Teethmate F-1 (Kuraray Noritake, Tokyo, Japan)—a fluoride-releasing unfilled sealant—exhibited the maximum abrasive wear, with ∆W and ∆D values of 1.14% ± 0.37% and 12.84 ± 4.28 µm, respectively. Delton (Dentsply Sirona, Charlotte, North Carolina, United States), a light-cured unfilled sealant, showed the minimum abrasive wear, with ∆W and ∆D values of 0.41% ± 0.09% and 2.93 ± 1.23 µm, respectively. No statistical differences were observed among unfilled sealants except when compared with Teethmate F-1. Similarly, no differences were observed when comparing among filled sealants and flowable composite. Conclusion Abrasive wear occurred in all sealants after brushing with dentifrice. Almost all unfilled sealants showed less wear compared with both filled sealants and flowable composite. However, the low abrasive values of all sealants after brushing with dentifrice implied that there is no clinical significance to this finding.

In Vitro Microleakage Comparison of Flowable Nanocomposites and Conventional Materials Used in Pit and Fissure Sealant Therapy.

Objectives:Pit and fissure sealants are recognized as an effective preventive approach in pediatric dentistry. Composite resin is the most commonly used sealant material. Adding nanoparticles to composite resin could result in production of flowable composite with higher mechanical properties and better flowability than previous sealants. This study aimed to compare the microleakage of a flowable nanocomposite and materials conventionally used as pit and fissure sealants.Materials and Methods:A total of 185 extracted mandibular third molar teeth were selected and randomly divided into 5 groups (n=36): flowable nanocomposite, flowable composite, filled sealants, nano-filled sealants, and unfilled sealants. Five teeth were reserved for examination under a scanning electron microscope (SEM). The samples were thermocycled (5–55°C, 1-minute dwell time) for 1000 cycles and immersed in 0.2% fuchsine solution for 24 hours. Teeth were sectioned buccolingually. Microleakage was assessed qualitatively and quantitatively by means of dye penetration and SEM. Data were analyzed using chi-square, Kruskal-Wallis, and Bonferroni-corrected Mann-Whitney U tests.Results: Qualitative microleakage assessment showed that flowable composite and nanofilled flowable composite had almost no microleakage (P<0.001). Regarding quantitative scores, the nanofilled flowable composite and unfilled fissure sealant showed the lowest and the highest rate of microleakage, respectively. No statistically significant difference was found between the two flowable composites (P=0.317). Filled resin-based sealant had significantly lower microleakage than unfilled resin-based sealant (P<0.001).Conclusion:Use of flowable and nanofilled flowable composites (but not unfilled resin-based fissure sealant) is recommended for sealing of pits and fissures of molars.

Retention of a flow able unfilled composite resin in comparison to a dual staged conventional posterior restorative and flow able unfilled resin-based sealant

Introduction: Dental caries in pits and fissures lead to various preventive inventions and creativity as blocking the pit and fissures and fluoride treatment. This effort against pit and fissure caries continues, and latest innovations in new materials and technologies tested each year. Keeping this these points in view a study was designed to assess the retention of flowable unfilled composite resin in comparison to a dual staged flowable unfilled and conventional resin-based sealant. Materials and methods: The experimental study was conducted in 30 children aged6 and 10 years, who visited the Public Health Dentistry Department, Vyas Dental College and Hospital. Screening was carried out by trained examiners using plain mouth mirrors, explorers, tweezers and pit and fissure sealants (Clinpro™ Sealant Fissure and filtek P 60 posterior restorative), and light cure. The statical analysis was done by using SPSS version 21(Chicago, USA). The p value? 0.05 was found to be statistically significant. Result: When retention was compared between Clinpro and Clinpro + Filtek P60 after 3 months and 6 months, the difference was statistically significant (p= 0.039 and 0.026 respectively, S.) shows when compared the mean surface retention and standard deviation it was found that the mean surface retention was in Clinpro then Clinpro + Filtek P60 higher after 6 months (0.600), as compared to 3 months (0.466). Conclusion: The resin-based unfilled pit and fissure sealant (Clinpro) clinically performed better when compared to and Clinpro (unfilled) resin-based pit and fissure sealants+ Filtek P60 (posterior restorative). Keywords: Pit and fissure sealants, Surface retention, Filled and unfilled resin, Dental caries, Marginal integrity

Effect of new light curing units on microleakage and microhardness of resin sealants.

To determine new developed light curing units with shorter curing times effects on microleakage and microhardness values for resin fissure sealants. Resin filled sealant (UltraSeal-XT), resin unfilled sealant (Delton Type-II) and ormocer-based sealant (Admira-Seal) were light cured with a quartz-tungsten-halogen (QTH), two LED light and a high power LED. Two hundred and forty extracted human molars were randomly allocated into four groups according to used light-curing unit and three subgroups were formed for three different fissure sealant materials. Specimens were immersed in 0.5% basic fuchsin for 24 h, sectioned and examined under a stereomicroscope, and scored for marginal microleakage. Knoop hardness number (KHN) readings were measured after 48 h. Statistical analyses of test were found in significant difference both microleakage and microhardness values between the various light curing units. The time saving approaches in the curing light were determined higher microhardness, although it was found in higher microleakage.

Efficacy of light-activated sealant on enamel demineralization in orthodontic patients: an atomic force microscope evaluation.

Objective:The purpose of this study was to investigate the efficacy of (Pro Seal) sealant in preventing enamel decalcification in-vivo and compare its effect with fluoride varnish and unfilled sealant using atomic force microscopy. Materials and Methods:Eight orthodontic patients who were candidates for extraction of all first premolars for orthodontic treatment were recruited to this study. Thirty two premolars (upper and lower) were randomly divided into four groups (n=8) for each group, 4 maxillary and 4 mandibular); Control (no -treatment); Fluoride varnish, Unfilled sealant (Light Bond) and filled sealant (Pro-Seal). After two months the brackets were debonded and the teeth were extracted and prepared for Atomic force microscopic scanning. Each sample was scanned twice at two different scan areas 50 and 10µm at the buccal cervical third of the crown. Images were recorded with slow scan rate and resolution and the mean roughness height and total surface area were calculated for each scan area. Comparison between groups was performed using one way analysis of variance test with level of significance was set to be 0.05.Results:Pro Seal treated samples show the lowest roughness height and total surface area.Conclusion:Pro Seal was the most effective prophylaxis technique in preventing enamel demineralization during orthodontic treatment.

Effect of Tooth Preparation on Sealant Success—An in vitro Study

This study compared the depth of penetration and marginal leakage of filled and unfilled sealants, with and without tooth preparation. One hundred and twenty extracted human third molar teeth that were free of restorations, fluorosis, caries, and sealants were used. After adequate storage and surface debridement, the teeth were randomly divided into four groups of 30 teeth each. In two groups, the occlusal surfaces were left intact, while in the other two groups, the occlusal surfaces were prepared using a diamond bur. Teeth in two groups were sealed with a filled sealant, and an unfilled sealant was used to seal teeth in the other two groups. The sealed teeth were then prepared for marginal leakage, immersed in 5% methylene blue (at 37 degrees C) for 24 hours. Subsequently, buccolingual sections were made and each section was examined for sealant penetration and marginal leakage, using a stereomicroscope. The depth of dye penetration and marginal leakage was evaluated according to a method described by Ovrebo and Raadal. The unfilled sealant placed after tooth preparation showed better enamel fissure penetration and less marginal leakage than the filled sealant.

Tailored Polyethylene Nanocomposite Sealants: Broad-Range Peelable Heat-Seals Through Designed Filler/Polymer Interfaces

The heat sealing behavior of novel polyethylene-based nanocomposite films was investigated, as they relate to flexible packaging of fresh-cut vegetables, processed foods and biomedical devices. Appropriately designed sealant nanocomposites, which include dispersed montmorillonite nanofillers and ethyl vinyl acetate copolymer, produce a hermetic but peelable heat seal across a broad, 30–40°C, range of heat sealing temperatures, outperforming optimized commercial polyethylene-based sealants that achieve peelable seals in a much narrower heat sealing temperature range, of less than 15°C. Appropriate nanocomposite design leads to a general easy-open/peelable character of heat seals, which is: (a) independent of sealing conditions and apparatus — ranging from long dwell times at very high sealing pressures to very short heat impulses at very low sealing pressures; (b) markedly independent of the opposite side of the heat seal — for example, when sealed on itself, on unfilled sealant, or on high density polyethylene; and (c) rather insensitive to formulation variations of the sealant — for example, variations of the polyethylene of the ethyl vinyl acetate type and concentration, and of nanofiller loading. Insights from observations of the fracture seal surfaces by infrared spectroscopy and electron microscopy reveal that the underlying mechanism of this behavior is related to a synergistic effect of the ethyl vinyl acetate copolymer and the montmorillonite clay nanofiller, which introduces weak interfaces in the nanocomposite that lead to cohesive failure of the sealant.

Filled and unfilled restorative materials to reduce enamel decalcification during fixed-appliance orthodontic treatment

Enamel decalcification is a potential problem that can compromise the esthetic results of orthodontic treatment. Patient compliance with preventive measures is frequently inadequate to resolve this issue. The purpose of this study was to determine the effectiveness of sealing around the bracket periphery in reducing decalcification. Sixty extracted teeth were collected and randomized to 4 groups: group 1, bonded and then sealed around the bracket with an unfilled sealant material; group 2, bonded and then sealed with a filled, flowable composite material; group 3, bonded and sealed with excess bracket adhesive contoured at bracket periphery; and group 4, conventional treatment with excess bonding material removed and no additional protection at the bracket periphery. Each group was subjected to mechanical, thermal, and decalcification challenges to simulate in-vivo conditions. Groups 1 and 2 had the lowest incidence of decalcification; however, decalcification was not statistically significantly reduced by the use of an additional restorative/bracket adhesive material. An incidental finding was a statistically significant loss of bracket adhesive material beneath the bracket pads of group 4. Prophylactic sealing around the orthodontic bracket pad periphery with an unfilled sealant or a filled flowable composite restorative material did not significantly reduce the incidence of decalcification.

Effect of 10% Carbamide Peroxide Dental Bleaching on Microhardness of Filled and Unfilled Sealant Materials

The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials. Fluroshield, Vitroseal Alfa, and one unfilled (Clinpro) sealants were placed in Teflon matrices (4 mm in diameter by 2 mm in height) and polymerized for 40 seconds. A total of 20 specimens were prepared for each material, in which half were assigned as the control group (stored in artificial saliva and no bleaching treatment). For the remaining half, Clarigel Gold bleaching agent (10% carbamide peroxide) was placed over the specimen surface for 4 hours/day during 4 weeks. When specimens were not under bleaching treatment, they were kept in artificial saliva. Afterwards, specimens were subjected to Knoop microhardness testing using a 25-g load for 5 seconds. Five measurements were made on the sealants' surfaces and then calculated in Knoop hardness values. The data were statistically analyzed by two-way analysis of variance and Tukey's tests with a 5% confidence level. The results of this in vitro study showed that the application of a carbamide peroxide-based bleaching material significantly affected the microhardness values of filled sealant materials. The bleaching agent did not affect the microhardness of the unfilled sealant. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that the bleaching agents altered the surface hardness of filled sealant restorative materials. This could possibly lead to increased wear and surface roughness.

Prevention of enamel demineralization: An in-vitro study using light-cured filled sealant

Enamel demineralization is an undesirable side effect of orthodontic treatment with fixed appliances. The purpose of this in-vitro study was to evaluate the efficacy of applying a light-cured filled sealant onto the buccal tooth surfaces to prevent demineralization. Fifty extracted human third molars were allocated to 1 of 5 groups: (1) enamel surface untreated (control); (2) surface etched; (3) fluoride varnish applied; (4) enamel etched and coated with a light-cured, unfilled sealant (control sealant); and (5) enamel etched and coated with a light-cured, filled sealant (Pro Seal, Reliance Orthodontic Products, Itasca, Ill). The enamel surface of each specimen was brushed for 15,000 strokes with nonfluoride toothpaste slurry with a piston-action brushing machine under a standardized load. All samples were then cycled for 14 days through a daily procedure of demineralization for 6 hours and remineralization for 17 hours. Then the teeth were sectioned and evaluated quantitatively by cross-sectional microhardness testing. Demineralization in the Pro Seal group was significantly less (P < .05) than in the other groups. Teeth treated with fluoride varnish exhibited 30% less demineralization than the control teeth, the enamel-etched teeth, and the teeth treated with a light-cured, unfilled sealant (P < .05). Pro Seal can be considered for use as a preventive method to reduce enamel demineralization adjacent to orthodontic attachments, particularly in patients who exhibit poor compliance with oral hygiene and home fluoride use.

Bond strengths and remnant adhesive resin on debonding for orthodontic bonding techniques

Bond strengths and remnant adhesive resin on the tooth surface after debonding for three bonding techniques used to attach foil mesh orthodontic brackets to 315 freshly extracted bovine incisor teeth were compared in an in vitro study. Each method of bonding used 105 teeth in groups of 15, bonded with seven different (bis-GMA type) two-paste chemically cured resins. The direct method comprised bonding the attachments directly to the incisors with the composite resin. The indirect-1 method comprised securing attachments to die-stone models of the teeth with a water soluble glue, making silicone positioners to transfer the brackets from the models to the teeth, and bonding to the teeth with the use of the two-paste composite resin system. The indirect-2 method comprised bonding the attachments to die-stone models of the teeth with composite resin, making silicone positioners to transfer the brackets from the models to the teeth, and bonding to the teeth with the use of unfilled sealant resin. Significant differences in bond strength existed among the groups evaluated. The direct technique had statistically significant ( p < 0.05) higher bond strength as compared with the indirect-1 and indirect-2 techniques in four of the seven groups evaluated. The indirect-1 and indirect-2 techniques were not significantly different ( p < 0.05) in bond strength in six of seven groups tested. The indirect-2 technique had significantly lower adhesive remnant index scores (ARI) compared with the direct and indirect-1 techniques. The direct technique had significantly lower adhesive remnant indices compared with the indirect-1 technique. Thus the indirect-2 technique of bonding orthodontic brackets to teeth demonstrated comparable laboratory bond strengths and easier clean-up during the debonding procedure. (A M J O RTHOD D ENTOFAC O RTHOP 1995;108:302-7.)

Change in occlusal height resulting from placement of pit and fissure sealants

This in-vitro study was done to identify the amount of change in occlusal height resulting from standard sealant application technique and to determine whether this change was uniform for both a filled and an unfilled sealant material. Twelve dental hygienists experienced in sealant technique each applied 10 filled sealants and 10 unfilled sealants in standardized artificial teeth mounted in a dentiform and mannikin setup in a dental unit. The teeth were measured with a digital caliper before and after sealant placement. Measurements were from a predetermined point at the apical area of the teeth to the depth of the central fossa. For the sample of 240 teeth, the mean sealant thickness was 0.43 ± 0.20 mm. When the data for the filled and unfilled sealants were examined separately, the means were 0.47 ± 0.23 mm and 0.38 ± 0.16 mm, respectively. A t-test indicated a significant difference at p < 0.001. Analysis of variance revealed significant interoperator differences in sealant thickness ( p < 0.01).

Occlusal discrepancies after sealant therapy

To date there has been no evidence concerning the need for adjusting the occlusion after sealant placement. Thus, this study investigated the occlusal effects of filled and unfilled sealants. For each of 18 subjects a sealant was applied and the occlusion monitored for 1 week. Each participant received a filled and an unfilled sealant for the specified period. With the filled sealant, nearly all subjects experienced a perceptable occlusal change and most were unable to abrade the interferences to a comfort level. These results indicate that the occlusion should be routinely verified and, if necessary, adjusted immediately after placement of a filled sealant.

Laboratory studies of visible-light cured fissure sealants: setting times and depth of polymerization.

Measurements were made, using an acoustic transmission method, of the setting times of three visible-light curing sealants (two filled, one unfilled). Five commercially available visible-light polymerizing sources were tested with each material. Only three of the light sources gave setting times not significantly different from the manufacturers' recommended times for all three materials tested. The variation in microhardness with depth of sealant was measured to study the depth of polymerization of the sealants, all of which were adequate. The filled sealants had microhardness values greater than the unfilled sealant, at all depths studied.