Effect of enamel preparation method on in vitro marginal microleakage of a flowable composite used as pit and fissure sealant

OBJECTIVES

The aim of this in vitro study was to evaluate the microleakage in occlusal surfaces, after preparation with Er:YAG laser and compared to the diamond-bur conventional technique.

METHODS

Thirty premolars were divided into three groups: I - high-speed handpiece + 37% phosphoric acid; II - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + 37% phosphoric acid; and III - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + Er:YAG laser (80 mJ, 4 Hz, and 25 mJ/cm(2)). All cavities received the same adhesive system and were restored with flowable composite according to manufacturer's instructions. Teeth were submitted to thermal cycling and immersed in 50% silver nitrate solutions for 8 h in total darkness. Specimens were sectioned longitudinally in the bucco-lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution and was photographed, and microleakage was scored from 0 to 7, by three calibrated examiners.

RESULTS

A statistically significant difference (P < 0.0001) was observed between Er:YAG laser prepared and etched specimens and those in the other groups.

CONCLUSIONS

It can be concluded that no significant difference was noted between the two types of enamel preparation when etching was performed. Preparing and treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.

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

PURPOSE

The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials.

METHODS

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.

RESULTS

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.

Performance of a Conventional Sealant and a Flowable Composite on Minimally Invasive Prepared Fissures

Preparation prior to fissure sealing did not enhance the performance of the sealant. However, if caries is suspected and an enameloplasty has to be performed, opening the fissure with a diamond bur and sealing it with a conventional sealer is recommended.

An in vitro evaluation of the effect of sealant characteristics on laser fluorescence for caries detection

PURPOSE

The purposes of this study were to: (1) evaluate the ability of a laser fluorescence (LF) unit to detect simulated caries under pit and fissure sealants; (2) determine the effect of an opacifying agent in sealants on LF values; and (3) determine interexaminer reproducibility values of the unit in a highly controlled, laboratory setting. Sealant characteristics specifically considered were: (1) filler content; (2) opacity; and (3) intrinsic fluorescence.

METHODS

Three sealants were used in this study: 2 unfilled and 1 filled. To evaluate the effect of an opacifying agent, titanium dioxide powder was added to both filled and unfilled sealants. 0.5-mm thick sealant discs were prepared for all samples. The sealant discs were individually placed on top of 3 wells filled with varying amounts of protoporphyrin IX, a fluorescent material that mimicked dental caries. A total of 270 readings were made through the different sealant discs to evaluate signal attenuation of the laser fluorescence unit.

RESULTS

Clear sealants, without an added opacifying agent, attenuated LF readings. At baseline protoporphyrin IX levels yielding DIAGNOdent readouts of 20 and 60, there was a significant difference in the LF readings between the baseline protoporphyrin (uncovered) and with sealant disc covered in all 3 sealant types (P<.001). Furthermore, the filled sealant attenuated LF signals significantly more than the unfilled sealant (P<.001). Sealants with titanium dioxide added had variable levels of intrinsic fluorescence. Titanium dioxide added to the sealants also had a profound effect on fluorescence transmission of the underlying simulated caries. As the concentration of titanium dioxide approached 0.5%, the fluorescence signal was almost fully attenuated.

CONCLUSION

Clinical detection of caries under dental sealants with the use of laser fluorescence units is unreliable and not recommended due to a high likelihood of inaccurate readings caused by: (1) intrinsic fluorescence of sealant material; and (2) attenuation of fluorescence signals by the sealant.

Resin composite sealant vs. polyacid-modified resin composite applied to post eruptive mature and immature molars: two year clinical study

The aim of this study was to evaluate the effect of the post eruptive enamel maturation on the durability of polyacid-modified resin composite (PMRC; Dyract Seal) and resin composite (Fissurit F) sealant and understanding the effect of posteruptive enamel maturation on the sealant retention. To determine the possible effect of the enamel maturation to the sealant retention, the success of the sealants applied to the newly erupted mandibular first molars of the 6 to 7 years old children, who were in the fourth or fifth eruption stage according to Dennison's classification were compared with the sealants applied to first mandibular molars which were in the mouth at least for two years of the 9 years old children. The molars of the younger children were accepted as immature and the elders were posteruptively mature. The sealant retention was evaluated for two years. At the end of two years the retention rates of Dyract Seal were significantly lower. Maturation has no effect on the sealant retention. Dyract Seal application after NRC conditioning is not recommended.

Fluoride release rate from an orthodontic sealant and its clinical implications

The objectives were to measure the rate and amount of fluoride ions released from the sealant over a period of 17 weeks and to determine whether the fluoride-releasing sealant has a recharging ability when fluoride ions are reintroduced into the environment. Disc-shaped specimens were prepared from two types of sealants: (1) 10 discs were made using a fluoride-releasing sealant and (2) 10 discs were made of a nonfluoride adhesive primer (control). An ion analyzer was used to measure the fluoride release using a fluoride ion-specific combination electrode. The results of the repeated measure analysis (F = 7.76) indicated that the fluoride-containing sealant released fluoride ions into the solution in sustained but significantly (P = .014) decreasing rates from a high of 0.074 +/- 0.04 ppm/week/mm2 in the first week to a low of 0.015 +/- 0.017 ppm/week/mm2 at the end of the 17th week. Furthermore, the Pro Seal discs had the ability to be recharged with fluoride ions introduced from a foaming solution of acidulated phosphate fluoride. The mean fluoride release rate one week after recharging was 0.354 +/- 0.095 ppm/week/mm2 and decreased to 0.014 +/- 0.009 ppm/week/mm2 after eight weeks. The control sealant showed no significant fluoride release and was unable to absorb the fluoride ions available in the solution. The fluoride-containing sealant Pro Seal released fluoride ions in sustained but significantly decreasing amounts. The Pro Seal discs had the ability to be recharged with fluoride ions.

Effect of Placing a Clear Sealant on the Validity and Reproducibility of Occlusal Caries Detection by a Laser Fluorescence Device: An in vitro Study

The principal aim of this in vitro study was to assess the validity and reproducibility of the detection of occlusal caries using laser fluorescence (LF), prior to and following the placement of a clear fissure sealant. It also aimed to compare the manufacturer's standard cut-off recommendations with those published for in vitro studies and to compare the validity and reproducibility of LF with clinical visual examination (CVE) for the detection of occlusal caries under sealants. Three clinicians independently examined visually and with LF 37 extracted teeth (25 molars, 12 premolars), with a range of clinical caries from apparently sound to cavitated dentinal caries. Examinations were conducted under dental surgery conditions. Subsequently, the teeth were serially sectioned to provide the validating criterion. Following placement of the sealant, the specificity generally increased but there was an associated loss of sensitivity, at both the D1 (enamel and dentine) and D3 (dentine) diagnostic thresholds. The LF readings were significantly lower after placement of the sealant (p<0.05). The manufacturer's recommended cut-offs appear to be the most appropriate to use. The CVE had superior validity and reproducibility when compared to LF. Overall, the placement of a clear sealant does influence the detection of caries by LF but does not prevent the detection of caries by this method.

A field trial of resin-based and glass-ionomer fissure sealants: clinical and radiographic assessment of caries

OBJECTIVE

The purpose of the present study was to provide further data for comparison of retention and caries-preventive effect of a resin-based sealant (Delton, and a glass-ionomer sealant (Fuji III).

METHODS

The study was conducted in the municipality of Vaerløse located 15 km north of Copenhagen, Denmark in the period 1996-2001. The study comprised 153 children aged 8-13 years with a total of 364 site-pairs. Caries was diagnosed both clinically and radiographically, and sealant retention was diagnosed clinically. Sealants were placed either by one of four dentists, who had the responsibility for the children's dental care, by a dental hygienist or a dental assistant. Mean follow-up time was 38-39 months for sites on first permanent molars and 28-29 months for sites on second permanent molars.

RESULTS

The retention rates were consistently, and considerably lower for Fuji III than for Delton. Relative risks of caries in Delton-sealed teeth over Fuji III-sealed teeth was 0.435 (95% CI 0.150-0.846) based on the clinical diagnosis, and 0.559 (95% CI 0.342-0.905) based on the radiographic diagnosis. The ratio of the relative risks (clinical over radiographic diagnosis) was close to 1 (0.778; 95% CI 0.272-1.481).

CONCLUSION

In the present study, Delton-sealed teeth had a lower risk than Fuji III-sealed teeth of developing caries, independent of the caries diagnostic method used.

Exposure to bisphenol A from bis-glycidyl dimethacrylate-based dental sealants

BACKGROUND

Bisphenol A (BPA) is a common component of composites and dental sealants. The potential exists for human exposure after sealant placement.

METHODS

The authors prospectively enrolled 15 men in an exposure assessment study; 14 completed the study. After placement of clinically appropriate amounts of one of two sealants, the authors measured BPA in saliva and urine samples collected at prescribed intervals after the sealants were placed. They used selective and sensitive isotope-dilution mass-spectrometry-based methods for BPA measurements, thus providing the most reliable results.

RESULTS

Helioseal F (Ivoclar Vivadent, Amherst, N.Y.) leached negligible amounts of BPA. Urinary and salivary BPA levels in subjects who received these sealants were similar to baseline levels. Delton Light Cure (LC) Opaque pit-and-fissure sealant (Dentsply/Ash, York, Pa.) leached more BPA, resulting in low-level BPA exposures similar to those used in laboratory animal testing. BPA exposure after Delton LC sealant placement was significantly higher than exposure after placement of Helioseal F. Patients treated with Delton LC had significantly higher doses of BPA (110 microg) than did those treated with Helioseal F (5.5 microg) (P < .0001).

CONCLUSIONS

Placement of clinically relevant amounts of Delton LC sealant resulted in low-level BPA exposure; however, exposure was negligible after placement of Helioseal F. Saliva collection after sealant placement likely reduced systemic absorption of BPA from dental sealants. Sealants should remain a useful part of routine preventive dental practice, especially those that leach negligible amounts of BPA.

CLINICAL IMPLICATIONS

Dental sealants may be a point source for low-level BPA exposure at levels that show health effects in rodents. Further research is required to determine whether human exposure to BPA at these levels causes adverse effects.

Wear resistance and surface roughness of a newly devised adhesive patch for sealing smooth enamel surfaces

A laboratory study assessed the wear resistance and surface roughness after chemical and mechanical wear of a newly devised adhesive patch when used as a smooth surface sealant. Forty-eight enamel discs were prepared from bovine lower central incisors. Sixteen specimens were treated with one of two sealing options: the prototype of an adhesive patch or a flowable resin. Unsealed enamel served as the positive control. Wear and surface roughness was measured at baseline and after all the samples were immersed in saliva or lactic acid (n=8 per treatment group) for up to 21 days, during which the experimental and control enamel surfaces were exposed to 10 double-stroke toothbrush cycles per day. In saliva and lactic acid, the sealed specimens showed no significant wear during the observation period (p=0.1841). Only untreated specimens exposed to lactic acid showed a significant substance loss after 14 and 21 days (p=0.0186). The patch and flowable resin showed no differences in surface roughness values at respective times (p=0.385); whereas the surface roughness of the unsealed specimens in lactic acid was significantly higher (p<0.0001). It was concluded that the adhesive patch under investigation merits further study to assess its potential as a sealant for smooth enamel surfaces.

In vitro evaluation of microleakage of different materials used as pit-and-fissure sealants

The aim of this study was to evaluate in vitro the marginal microleakage of different materials used as pit-and-fissure sealants (Delton, Filtek Flow, Dyract Flow and Vitremer). Fifty-six extracted sound human third molars were randomly assigned to 4 groups (n=14). After sealant placement, the teeth were thermocycled (500 cycles; 5 degrees C, 37 degrees C and 55 degrees C), isolated, immersed in 2% buffered methylene blue dye for 4 h, included in acrylic resin and sectioned longitudinally in a buccolingual direction. The sections were analyzed for leakage using an stereomicroscope. A 4-criteria ranked scale was used to score dye penetration. All materials exhibited dye penetration to some extension and no statistically significant difference was observed among the groups (p>0.05). In conclusion, the findings of this study showed that a flowable composite resin, a flowable compomer and resin-modified glass ionomer placed on occlusal pits and fissures had similar marginal sealing as the unfilled self-cured resin-based sealant.

Evaluation of the tissue response to MTA and MBPC: Microscopic analysis of implants in alveolar bone of rats

The aim of this study was to evaluate and compare the quantitative and qualitative inflammatory responses and bone formation potential after implantation of polyethylene tubes filled with a new calcium hydroxide containing sealer (MBPc) and ProRoot mineral trioxide aggregate (MTA). There were 48 Wistar rats divided in three groups: Group I (control group) empty polyethylene tubes were implanted in the extraction site; group II and III, polyethylene tubes were implanted filled with ProRoot mineral trioxide aggregate (MTA) and MBPc, respectively. At 7, 15, and 30 days after tube implantation, the animals were killed, the hemi-maxillas were removed and prepared to light microscopic analyses. The scores obtained were submitted to Kruskal-Wallis statistical test (p < 0.05). Significant differences between the materials were not observed. The results showed that both materials had similar biological response.

Clinical application of an adhesively bonded fiber post and Resilon

Traditionally, caring for endodontically treated teeth has represented a challenge in restorative dentistry. These teeth can experience apical or coronal leakage, root fractures, and various other complications that predispose the treated canal for reinfection and eventual failure. Thus, as such teeth will subsequently receive restorative care, representing a greater cost and effort for both dental patient and professional, it is imperative that the canal be stabilized through a diligent endodontic procedure. This article demonstrates the application of an adhesively bonded fiber post and a synthetic, polymeric root-filling material (Resilon) for the restoration of endodontically treated teeth.

Efficacy of composite surface sealers in sealing cavosurface marginal gaps

OBJECTIVES

The ability of commercially available composite surface sealers to penetrate and seal a controlled gap formed in all-enamel margin, Class V in vitro resin composite restorations in human bicuspids was examined.

METHODS

A fluorescent red dye (Rhodamine B) was incorporated to a variety of commercially available composite surface sealers. The teeth were restored using acid etching, a dentin bonding agent, and a photo-activated microfilled composite, finished, polished, and sealed. The teeth were thermocycled and then immersed in an aqueous solution of a green fluorescent dye (Dextran-Fluorescein) to evaluate the sealing ability and penetration of surface sealers into the controlled gaps formed at unbonded margins. Teeth were embedded, sectioned, and images recorded using confocal microscopy.

RESULTS

All sealers leaked, and use of a dentin-bonding agent to seal the gap performed better than the commercial sealing products.

CONCLUSIONS

Commercial surface sealers evaluated were not able to totally seal controlled-size cavosurface gaps, and sealer penetration into the controlled gap varied greatly. Composite restorative procedures should be performed to obtain ideal marginal sealing, minimizing the need for composite surface sealers, which were found to not totally seal an exposed cavosurface margin. Use of a dentin-bonding agent may provide better sealing than commercial products developed specifically for this purpose.

Caries-preventive potential of an adhesive patch after thermomechanical loading--a microbial-based in vitro study

PURPOSE

To assess the enamel-protective potential of a newly devised adhesive patch for smooth enamel sealing.

MATERIALS AND METHODS

Approximal surfaces of 30 extracted molars were divided into three areas: the buccal thirds were treated with a flowable composite (Tetric Flow, Ivoclar Vivadent) and served as negative control sites, the lingual thirds were left untreated and served as positive control sites, and the middle thirds served as the test areas. This was sealed with either 1. a twofold application of an unfilled resin (Heliobond, Ivoclar Vivadent), 2. an adhesive prototype patch (Ivoclar Vivadent), or 3. an adhesive patch in combination with a flowable composite. After thermomechanical loading and demineralization in a microbial-based artificial caries chamber, demineralization depth was assessed using a confocal laser scanning microscope.

RESULTS

Negative control sites treated with the flowable composite showed no signs of demineralization. Areas treated with the patch showed no signs of demineralization, irrespective of whether it was used in combination with a flowable composite or directly bonded to the enamel. Caries-like lesions in untreated sites showed a mean depth of 134.3 +/- 35.9 microm. Demineralization depth at sites treated with the unfilled resin was 76.2 +/- 26.5 microm (p = 0.023).

CONCLUSIONS

Under the conditions of the present study, the adhesive patch under investigation completely protected the underlying enamel from demineralization. This merits further study to assess its potential as an interproximal sealant.

The impact of ozone treatment on enamel physical properties

PURPOSE

To assess the effects of the highly reactive molecule of ozone on sound enamel physical properties and its effects on sealing ability.

METHODS

The effect of ozone on sealant tag length, microleakage and unfilled area proportion were evaluated on intact and prepared sound molar fissures. Microhardness, contact angle and acid resistance tests were performed on ground sound smooth surfaces. The samples were treated with ozone for 40 seconds (HealOzone). Control samples were treated with air (modified HealOzone) or left untreated.

RESULTS

No statistically significant difference was observed between the control and ozone treated samples in all tests. Prepared fissures exhibited no unfilled areas and a statistically significantly lower microleakage compared to intact fissures. Ozone was shown to dehydrate enamel and consequently enhance its microhardness, which was reversible.

Bond strength of 4 sealants using conventional etch and a self-etching primer

PURPOSE

The purpose of this study was to determine and compare the shear bond strength of 4 fissure sealant systems (Dyract Seal, Concise, Visio-Seal, Helioseal) to enamel using conventional etch and self-etching primer (Prompt-L-Pop).

METHODS

Fifty-six newly extracted noncarious first permanent molars were used and embedded in a Teflon mold (3-mm height, 3-mm internal diameter). Mesial surfaces were exposed to a flattened area of enamel and then dried and washed. The teeth were divided into 8 groups, each consisting of 7 specimens stored in 37 degrees C distilled water for 24 hours. Then specimens were tested in a shear mode (Instron) at a crosshead speed of 0.5 mm/minute. The mean and standard deviations were subjected to an analysis of variance.

RESULTS

The average bond strengths using Prompt-L-Pop were: (1) Dyract Seal=20.61 MPa; (2) Concise=23.42 MPa; (3) Visio-Seal=2.94 MPa; and (4) Helioseal=11.83 MPa. These values were higher than and statistically different from those of Dyract Seal (10.18 MPa) and Concise (9.17 MPa) when the conventional etch system was used (student t test, P<.001).

CONCLUSION

The bond strengths of Prompt-L-Pop, in conjunction with Dyract Seal and Concise fissure sealant materials, exceeded those of conventional etch.

Polymerization kinetics and mechanical characterization of new formulations of light-cured dental sealants

The aim of the study was to develop and evaluate the in vitro performance of a new and simplified formulation of photocuring resin to be used as dental sealant. Two experimental dental sealants (CYTED1 and CYTED2) were formulated and their kinetic of polymerisation and physico-chemical properties were studied and compared to those of two commercially available sealants (Helioseal, Delton-FS). Rates of photoinitiated polymerisation (Rp), as well as the conversions and the quantum yields of polymerisation (phi(p)) were calculated. Flexural strength, Young's modulus, microhardness, microleakage, water sorption, and solubility were also tested. ANOVA, Student-Newman-Keuls, Pearson correlation and Kruskal-Wallis tests were used (p < 0.05). The highest Rp and phi(p) were obtained for the sealant CYTED2, Rp and phi(p) were similar for CYTEDl and Helioseal, and the lowest for Delton. Water sorption values were similar for Helioseal and CYTED2 being higher for CYTED1 and lower for Delton. No differences were found for solubility and microleakage values. Mechanical properties were better for Delton and no differences were found within the rest of the sealants. At short irradiation times (30 s), the maximum effectiveness of the photoinitiating system was obtained by the experimental CYTED2.

Influence of the application time on the penetration of different dental adhesives and a fissure sealant into artificial subsurface lesions in bovine enamel

Sealing of approximal enamel lesions by infiltration with low viscous resins seems to be a promising approach in non-operative dentistry and should bear advantages compared to remineralization or invasive treatment.

OBJECTIVE

The aim of this in vitro study was to evaluate the penetration ability of five dental adhesives and a fissure sealant into initial enamel lesions for an application time of either 15 s or 30 s.

METHODS

In each of 54 specimens of bovine enamel, three windows were demineralized for 14 days. Subsequently, two windows were etched with phosphoric acid for 5s in order to degrade the surface layer, whereas one window served as untreated control. The specimens were randomly divided into six groups and a fissure sealant as well as five different adhesives were applied onto the subsurface lesions and allowed to penetrate for either 15 or 30 s. Overlying material was wiped away and the resins were light cured. To visualize the penetrated resins and the remaining pore structures, the specimens were infiltrated with a low viscous fluorescent resin and studied using a Confocal Laser Scanning Microscope (CLSM).

RESULTS

For Helioseal, Heliobond, Resulcin Monobond, and Excite an application time of 30s resulted in significantly higher (p < 0.05; t-test) penetration depths (47-105 microm) compared to 15s (29-49 microm).

SIGNIFICANCE

Helioseal, Heliobond, Resulcin Monobond, and Excite are suitable for sealing artificial subsurface enamel lesions in vitro. After an application time of 30 s a significant deeper penetration could be observed for these materials.

Sealing ability of a new experimental "cold ceramic" material compared to glass ionomer

OBJECTIVE

The purpose of this study was to compare the sealing ability of a new experimental material named "cold ceramic" with glass ionomer using an electrochemical method.

METHODOLOGY

Forty extracted human teeth were used in this study. The crowns were removed at the cemento-enamel junction. The roots were prepared, the apical 3 to 4 mm of each root was resected, and a class 1 cavity of 2 mm depth was prepared. After application of nail polish to the external surface of the roots, the samples were randomly divided into two groups, each with 20 roots. Each sample was filled with one of the two materials. After 24 hours, to allow complete setting, the roots were immersed in normal saline solution for 10 days. Microleakage was measured by an electrochemical method.

RESULTS

The results indicated that there is a statistically significant difference in the microleakage between the two materials (p = 0.0001), with the cold ceramic providing a better seal than the glass ionomer.

CONCLUSION

Cold ceramic has proper sealing ability and reduced initial setting time that demonstrate its potential as a root end filling material.

Measurement of clinical wear of two packable composites after 6 months in service

Original large-particle composites exhibited poor wear characteristics. With the packable composites, there has been a reintroduction of large particles. The clinical wear characteristics of such packable composites are relatively unknown. The purpose of this study was to compare wear between two types of packable composites: Alert (Jeneric Pentron) and Surefil (Dentsply Caulk). Each material was compared with and without a surface sealant. Fifty-two subjects were included. Subjects had to have two to four eligible teeth, be 21 years of age, in good health and in need of moderate to large class 2 restorations on molars, and/or a two-surface class 1 on molars. Wear was assessed, using the Moffa-Lugassy (ML) scale, by evaluating stone models made from polyvinyl siloxane (PVS) impressions taken at baseline and 6 months. Rating was done by four calibrated examiners using a forced consensus model. The use of a surface sealant with Alert significantly reduced the median wear rate at 6 months compared with that of the SureFil restorations.

[Short-term fluoride release from conseal F fissure sealant in some media--an in vitro study]

INTRODUCTION

Low fluoride concentrations constantly maintained in the oral cavity are important for caries prevention. Application of fissure sealants containing fluoride improves protection and reinforces caries prophylaxis. The aim of this study was to assess the level of fluoride release from Conseal F fissure sealant in different media.

MATERIAL AND METHODS

Sealant samples were placed in (a) artificial saliva without calcium ions (C++) at pH of 4.5, 5.5, 6.0, 7.0, and 7.5, (b) artificial saliva with calcium ions (Ca") at pH 4.5, and 5.5, (c) saline, and (d) deionized water. Fluoride concentration in solution was measured after 1, 3, 24, 48, 72, and 168 hours from the start of the experiment.

RESULTS

The highest cumulative fluoride concentration was found in saline (9.39 +/- 2.17 microg F/mm(2)), the lowest in artificial saliva at pH of 7.0 (0.45+/-0.14 microg F/mm(2)). The highest fluoride emission was observed during the first three hours which then decreased to a low but relatively stable level.

CONCLUSION

The level of fluoride release from Conseal F fissure sealant depends on composition and pH of the medium. Decrease in pH increased fluoride release. This property is essential for patients with low salivary pH and high risk of caries.

Curing of pit & fissure sealants using Light Emitting Diode curing units

Light Emitting Diode (LED) curing units are attractive to clinicians, because most are cordless and should create less heat within tooth structure. However, questions about polymerization efficacy have surrounded this technology. This research evaluated the adequacy of the depth of cure of pit & fissure sealants provided by LED curing units. Optilux (OP) and Elipar Highlight (HL) high intensity halogen and Astralis 5 (A5) conventional halogen lights were used for comparison. The Light Emitting Diode (LED) curing units were Allegro (AL), LE Demetron I (DM), FreeLight (FL), UltraLume 2(UL), UltraLume 5 (UL5) and VersaLux (VX). Sealants used in the study were UltraSeal XT plus Clear (Uclr), Opaque (Uopq) and Teethmate F-1 Natural (Kclr) and Opaque (Kopq). Specimens were fabricated in a brass mold (2 mm thick x 6 mm diameter) and placed between two glass slides (n=5). Each specimen was cured from the top surface only. One hour after curing, four Knoop Hardness readings were made for each top and bottom surface at least 1 mm from the edge. The bottom to top (B/T) KHN ratio was calculated. Groups were fabricated with 20 and 40-second exposure times. In addition, a group using a 1 mm-thick mold was fabricated using an exposure time of 20 seconds. Differences between lights for each material at each testing condition were determined using one-way ANOVA and Student-Newman-Keuls Post-hoc test (alpha=0.05). There was no statistical difference between light curing units for Uclr cured in a 1-mm thickness for 20 seconds or cured in a 2 mm-thickness for 40 seconds. All other materials and conditions showed differences between light curing units. Both opaque materials showed significant variations in B/T KHN ratios dependent upon the light-curing unit.

Evaluation of fissure sealant applied to topical fluoride treated teeth

Fissure sealant is an important tool in the prevention of dental caries. This study evaluated the effect of treating the enamel with topical fluoride gel prior to acid etching on sealant retention clinically (Part I) and in vitro (Part II). In part I a split mouth design using contralateral first permanent molars was conducted. Seventy (35 pairs) molars were sealed. Fissure sealant was applied on one side of the mouth (control group) and the contralateral tooth received acidulated phosphate fluoride gel (test group) prior to acid etching. The sealant was evaluated after 6 and 12 months and scored as intact, partially lost or completely missing. In part II, the shear bond strength between sealant and buccal enamel of extracted permanent molars without or with topical fluoride treatment was evaluated. Results showed no statistically significant differences between the test and control groups either clinically or in vitro. It is concluded that topical fluoride application prior to acid etching does not have a deleterious effect on sealant retention. However, further investigations should be conducted using different types of fluoride before altering the traditional practices.