Surface Coating on GIC in Pediatric Dentistry

7/18/2019 Surface Coating on GIC in Pediatric Dentistry

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Journal of Indian Society of Pedodontics and Preventive Dentistry | Oct-Dec 2013 | Vol 31| Issue 4 |229

ABSTRACT

Background: To know the effect of surface protectiveagents used in day-to-day practice on the fluoriderelease property of conventional glass ionomercements (GIC) and discuss its pros and cons. Materialsand Methods: Thirty disc-shaped specimens

were fabricated from conventional GIC and blockrandomized into three groups (Group I, II, and III) of10 each. Group I specimens were unprotected, groupII coated with cavity varnish (Namuvar, Ratnagiri,India) and group III with petroleum jelly (Vaseline,Hindustan lever ltd). After polymerization, the diskswere immersed in three individual sealable plasticbottles containing deionized distilled water whichwas changed every 24 hours for 15 days to measurethe fluoride release. Statistics and Results: Statisticalanalysis was carried using software version Systat 10.0,and the data was subjected to one way ANOVA, usingDuncan Multiple Range test (Variable LSD) with the

level of significance set at 0.05 (P < 0.05). The greatestamount of fluoride was released from the uncoatedgroup, followed in ranking by petroleum jelly andvarnish coated and the difference among themwas statistically significant (P < 0.05). Conclusion: Application of varnish over GIC can severely impedeits fluoride release property. Similarly petroleum

jelly also impedes the fluoride release, but to a veryless extent. We suggest that in situations where thefluoride release property is more important than otherproperties it is better to coat the GIC with petroleum

jelly or leave the restoration without any coating.

KEYWORDS: Glass ionomer cement, petroleum jelly,varnish

Surface coatings on glass ionomer restorations inPediatric dentistry-Worthy or not?

Rekhalakshmi Kamatham, Sharada Reddy J.1

Departments of Pedodontics and Preventive Dentistry, Narayana Dental College, Nellore, 1Pedodontics and Preventive Dentistry,Government Dental College and Hospital, Afzulgunj, Hyderabad, Andhra Pradesh, India

Introduction

Cariostatic activity in tooth colored restorations has

been a desirable characteristic in the entire history of

modern dentistry. The glass ionomer cements (GICs) are

one of the products developed in this direction and arewidely used in Pediatric operative dentistry because oftheir ability to adhere to/bond with enamel and dentin

without any pre-treatment and potential to releasefluoride ions over a prolonged period of time.[1,2] Otherpositive characteristics of GIC include biocompatibilitywith dental tissues, resistance to microleakage, goodmarginal integrity and dimensional stability at highhumidity, coefficient of thermal expansion similar totooth structure, and fluoride rechargibility, whereasthe GIC possesses undesirable characteristics likeearly moisture sensitivity, poor wear resistance, lowstrength and average esthetics.[1,2] To surmount theproblem of moisture sensitivity, the application ofdifferent coatings like water proof varnish, petroleum

jelly, cocoa butter, or chemical/light cured bondingresins over the surface of the material immediatelyfollowing the initial set to maintain the water balanceduring maturation have been suggested[3] and areembedded into practice. However, there is very limitedexisting literature on the influence of these protectivecoatings on GICs[4-6] and even that literature is focusedmainly on the manufacturer recommended ones. Therecent literature on GICs is concentrating primarilyon the procedural aspects,[7] crystal growth,[8] self-reparability[9] and on the properties of GICs containingchlorhexidine diacetate/cetrimide mixtures[10] andpoly quaternary ammonium salts,[11] but not on the

Address for correspondence:Dr. Rekhalakshmi Kamatham,

Assistant Professor, Department of Pedodontics and PreventiveDentistry, Narayana Dental College,Nellore, Andhra Pradesh, India.E-mail: [email protected]

Original Article

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Kamatham and Reddy: Surface coatings on glass ionomer restorations in pediatric dentistry

Journal of Indian Society of Pedodontics and Preventive Dentistry | Oct-Dec 2013 | Vol 31| Issue 4 | 230

influence of surface coatings on GIC. Hence, the presentinvestigation has been performed to evaluate the effectof these protective coatings on fluoride release fromone of the commercially available GIC, Fuji II, underin vitro conditions. The surface protective coatingsselected in the present study were cavity varnish andpetroleum jelly (vaseline) as they are routinely used inclinical practice.

Materials and Method

Conventional GIC, Fuji II (GC Corporation, Tokyo, Japan), was chosen for this study. Using standardizedbrass mold, 30 disk shaped specimens 11 ± 0.1 mmin diameter and 5 ± 0.1 mm thick, were fabricated.GIC was mixed according to the manufacturer’sinstructions and immediately covered with polyesterstrip. A glass slab was laid over the top and held underhand pressure to ensure proper placement. Initiallythey were protected from dehydration and moisturecontamination within their molds for a period of 10

minutes (100% relative humidity at 37ºC). Any excessmaterial around the periphery was removed with ascalpel and the glass ionomer surfaces were gentlypolished under water, using wet carborundum paper(32 grit, waterproof, Metallurgy consumables emerypapers, Chennai) in a small polishing machine. Theywere weighed to verify standardization (±0.01 g),block randomized into three groups of 10 each usingblock size of 6 and table of random numbers. Surfacecoatings that is for one group, cavity varnish (Namuvar,Ratnagiri, India) and for another group, petroleum

jelly (Vaseline, Hindustan lever ltd.) were appliedwith a brush and then gently air dried. Immediatelyafter polymerization, the disks were immersed in threeindividual sealable plastic bottles containing 50 ml ofdeionized distilled water to prevent small volume oftest solution becoming saturated with fluoride. The

average fluoride concentration in deionized waterwas <0.01 ppm. These were then left undisturbed inan incubator set at 37ºC. After 24 hours, the bottleswere removed from incubator and the tooth sampleswere grasped with clean metal forceps coated withnail varnish and washed with 1 ml of deionized waterusing a syringe, over the original holding bottle, thuscollecting the rinse water in that bottle. The samples

were dried for two minutes on absorbent paper andthen transferred to a new bottle containing 50 mldeionized distilled water. The deionized distilledwater was changed every 24 hours and release offluoride was measured for 15 days.

Fluoride release was determined after buffering thesolution with equal volumes of total ionic strengthadjustment buffer (TISAB II), Orion Research, Inc,Beverly, MA, USA). Fluoride release was measuredwith a combination of fluoride electrode (Orion9609BN, Orion Research Inc) and an ion analyzer(Orion EA 940, Orion Research Inc). Data concerningfl

uoride was recorded in parts per million (ppm).Statistical analysis was carried using software versionSystat 10.0, and the data was subjected to one-wayANOVA, using Duncan Multiple Range test (VariableLSD) with the level of significance set at 0.05 (P < 0.05).

Results

Total fluoride releaseAll the three groups of GICs evaluated for the fluoriderelease during the entire period of the experiment. Theamounts of fluoride released from the three groupsduring 15 days period are presented in Table 1. Thegreatest amount of fluoride was released from theuncoated group, followed in ranking by petroleum

jelly coated and varnish coated and the differenceamong them was statistically significant. Almost 97%

Table 1: Mean fl uoride release (in ppm) from GIC with or without surface coatings at different timeintervals in de-ionized water

Fluoride release from controlspecimens in ppm (Mean ± SD)

Fluoride release from varnish coatedspecimens in ppm (Mean ± SD)

Fluoride release from petroleum jellycoated specimens in ppm (Mean ± SD)

P -value

Day 1 13.04±0.06 0.47±0.004 10.27±0.03 P < 0.05

Day 2 10.48±0.13 0.22±0.007 7.25±0.05 P < 0.05

Day 3 8.35±0.24 0.17±0.003 6.32±0.02 P < 0.05

Day 4 7.19±0.10 0.13±0.005 5.43±0.02 P < 0.05

Day 5 6.12±0.10 0.11±0.003 4.26±0.05 P < 0.05Day 6 4.07±0.11 0.09±0.004 3.74±0.003 P < 0.05

Day 7 3.16±0.09 0.07±0.001 2.57±0.02 P < 0.05

Day 8 3.03±0.05 0.06±0.002 2.48±0.008 P < 0.05

Day 9 2.87±0.02 0.06±0.002 2.13±0.004 P < 0.05

Day 10 2.61±0.11 0.06±0.003 1.98±0.003 P < 0.05

Day 11 2.43±0.03 0.06±0.001 1.85±0.003 P < 0.05

Day 12 2.34±0.05 0.05±0.001 1.75±0.002 P < 0.05

Day 13 2.12±0.02 0.05±0.001 1.70±0.002 P < 0.05

Day 14 1.96±0.03 0.05±0.001 1.62±0.002 P < 0.05

Day 15 1.85±0.03 0.05±0.001 1.56±0.006 P < 0.05








by low, prolonged elution. This result is similar to thefindings of other studies on conventional and resinmodified glass ionomers.[20-27] Studies done using ionchromatography and ion selective electrodes havealso given consistent findings.[28-32] This pattern can beexplained by the proposed mechanisms concerningfluoride release from GICs, that is superficial rinse,diffusion through pores and micro fractures and mass

diffusion. Of these mechanisms initial superficialrinsing effect is credited for the high level of fluoriderelease on the first day, and diffusion through cementpores and fractures for the constant release in thefollowing days, whereas mass diffusion requires moretime than considered and consequently occurs with alonger cement contact with storage media.[33] When theamount of fluoride release is considered, application ofeither varnish or petroleum jelly resulted in decrease ofthe release. However, the decrease was dramatic in caseof varnish. Thus surface protection of GICs definitelyimpedes the fluoride release property which might bedue to the associated reduction in the movement ofwater. The surface coating might have occluded the

mechanism of superficial rinse and diffusion throughpores. Thus these findings of the present study affirmthose of others done on manufacturer recommendedsurface protective agents.

Parenthetically, it is a proved fact that exposure of GICimmediately to oral fluids after placement without anysurface protection will disturb the water balance in turnaffecting the setting reaction.[34] Disintegration of thesurface structure, increased surface roughness, inferiortranslucency and discoloration are documented.[35,36] Correlation between early exposure to water andpoor clinical performance has also been reported.[37] The reason for this has been attributed to washing outof Ca+2 and Al+3 ions and impaired acid base settingreaction, leading to improper matrix formation withinferior mechanical properties with lower compressivestrength.[38] It has also been documented in vitro that thesealing of the GIC material for at least 1 hour duringthe initial setting will produce specimens of optimumcompressive strength[29] and it has been attributed toincrease in the amount of bound water in the cement;contrarily higher shear punch strength of GIC at 24hours for uncoated specimens than for coated ones withno significant difference at longer time interval is alsoreported and they suggested for additional hydrationin order to develop maximum shear punch strength

rapidly.[5]

All these suggest that the subject of waterbalance in GICs is complicated, and though for most ofthe purposes, early protection of cements is desirable, itdoes not favor every aspect of cement maturation. Thusvarnish application on the surface of GI restorations forthe sake of improving the strength properties cannot berecommended in primary dentition, where the life spanof tooth itself is limited and as the chewing forces willbe comparatively less in children. If at all the dentistprefers to use a surface protective agent, petroleum jellycan be a viable alternative which has less hindrance onfluoride release.

of fluoride release was hampered when varnish wasused as a protective coating, thus indicating a dramaticdecrease in the release [Figure 1].

Pattern of fluoride releaseThe fluoride release in the present study showed aspecific pattern. There was an initial burst of releasein the first 48 hours and there was a gradual decreasein the release day-by-day irrespective of the surfacecoating employed.

Discussion

The fluoride release property of GICs is very importantespecially in Pediatric dentistry, as GIC is the materialof choice in techniques such as indirect pulp capping,alternative restorative treatment and interim therapeuticrestorations. The benefit of fluoride released from GIC isseen not only in enamel adjacent to the restoration, butalso has been reported in areas up to three millimetersaway from the restoration’s margin and may even

offer protection for the entire tooth.[12,13] The protectiverole will be more on decalcified dental tissues as theyare proved to be more reactive with fluoride, thuspreventing further demineralization.[14,15] Fluoride hasbeen found to neutralize the acid solutions and slightlyinhibit the acid production.[16] Also the concentrationsof fluoride released from freshly mixed GIC sampleshave been reported to be sufficient to inhibit and alterbacterial metabolism in vitro,[17] though not substantiatedby in vivo studies.[18,19] Hence the present study has beenconducted to determine the effect of the surface coatingson this very important property of GIC.

Despite the wide variations in the amounts of fluoridereleased in the present study, the pattern of releaseremained consistent irrespective of the surface coating.There was an initial burst of fluoride release followed

Figure 1: Mean fluoride release (in ppm) from GIC with or withoutsurface coatings at different time intervals in de-ionized water







Journal of Indian Society of Pedodontics and Preventive Dentistry | Oct-Dec 2013 | Vol 31| Issue 4 | 232

The major limitation of the present study is that we didnot compare the fluoride release from the specimens indifferent media, as studies have proved that amountof fluoride release under in vitro conditions was morein acidic and demineralizing-remineralizing regimens,followed by distilled water and the least in artificialsaliva.[39] As fluoride release is intermediate in distilledwater among the three, we have used it in the present

study. Another limitation is that we continued thestudy for only 15 days, the reason for this being aproved fact that the initial high amounts of fluoridedecrease rapidly after 24-72 hours and get plateauedto a nearly constant level within 10-20 days.[20,40] Beingan in vitro study is also a drawback as the influence oftooth brushing and dietary habits on the retention ofthese surface protective agents could not be assessed.Clinical studies are also necessary to compare theadvantages of different protective agents overconventional GICs, as results obtained from in vivo studies can differ from those of in vitro studies. Furtherstudies on the influence of these protective agents onthe fluoride rechargeability and re-release are alsonecessary, as they are very important properties ofGIC to be called a smart material in dentistry.

Conclusion

1. Application of varnish over GIC can severelyimpede its fluoride release property.

2. Application of petroleum jelly also impedes thefluoride release, but to a very less extent.

3. In situations where the fluoride release propertyis more important than other properties it is betterto coat the GIC with petroleum jelly or leave therestoration without any coating.

Thus the pediatric dentist should wisely decidewhether to apply surface coating or not, and if decidedto apply which one to be used.

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How to cite this article: Kamatham R, Reddy SJ. Surface

coatings on glass ionomer restorations in Pediatric dentistry-

Worthy or not?. J Indian Soc Pedod Prev Dent 2013;31:229-33.

Source of Support: Nil, Conflict of Interest: None declared.

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Surface Coating on GIC in Pediatric Dentistry