Review of the included articles was conducted independently by two reviewers. Differences were resolved by discussion and consensus. Trials were excluded if contains no computable data.

Trials excluded (with reason):
(1) Lin YC, Lai YL, Chen WT, Lee SY. Kinetics of fluoride release from and reuptake by orthodontic cements. Am J Orthod Dentofacial Orthop. 2008 Mar;133(3):427-34. No SD reported.
(2) Yan Z, Sidhu SK, Mahmoud GA, Carrick TE, McCabe JF. Effects of temperature on the fluoride release and recharging ability of glass ionomers. Oper Dent. 2007 Mar-Apr;32(2):138-43. No Mean, SD reported.
(3) Ariffin Z, Ngo H, McIntyre J. Enhancement of fluoride release from glass ionomer cement following a coating of silver fluoride. Aust Dent J. 2006 Dec;51(4):328-32. No Mean, SD reported.
(4) Can-Karabulut DC, Batmaz I, Solak H, Taştekin M.  Linear regression modeling to compare fluoride release profiles of various restorative materials. Dent Mater. 2007 Sep;23(9):1057-65. Epub 2006 Dec 11. No SD reported.
(5) Chan WD, Yang L, Wan W, Rizkalla AS.  Fluoride release from dental cements and composites: a mechanistic study. Dent Mater. 2006 Apr;22(4):366-73. Epub 2005 Aug 8. No SD reported.
(6) Tjandrawinata R, Irie M, Suzuki K.  Marginal gap formation and fluoride release of resin-modified glass-ionomer cement: effect of silanized spherical silica filler addition. Dent Mater J. 2004 Sep;23(3):305-13. No Mean, SD reported.
(7) Jost-Brinkmann PG.  Effect of air polishing on the fluoride release of (resin-modified) glass ionomer cements and of a polyacid-modified composite resin.  Clin Oral Investig. 1998 Jun;2(2):91-5. No Mean, SD reported.
(8) Komori A, Kojima I.   Evaluation of a new 2-paste glass ionomer cement. Am J Orthod Dentofacial Orthop. 2003 Jun;123(6):649-52. No Mean, SD reported.
(9) Osinaga PW, Grande RH, Ballester RY, Simionato MR, Delgado Rodrigues CR, Muench A. Zinc sulfate addition to glass-ionomer-based cements: influence on physical and antibacterial properties, zinc and fluoride release. Dent Mater. 2003 May;19(3):212-7. No Mean, SD reported.
(10) Ikebe K, Ettinger RL, Wefel JS.   In vitro evaluation of fluoride-releasing restorative materials for sealing the root canals of overdenture abutments.  Int J Prosthodont. 2001 Nov-Dec;14(6):556-62. No Mean, SD reported.
(11) Glasspoole EA, Erickson RL, Davidson CL.  Demineralization of enamel in relation to the fluoride release of materials.  Am J Dent. 2001 Feb;14(1):8-12. No Mean, SD reported.
(12) Karantakis P, Helvatjoglou-Antoniades M, Theodoridou-Pahini S, Papadogiannis Y. Fluoride release from three glass ionomers, a compomer, and a composite resin in water, artificial saliva, and lactic acid. Oper Dent. 2000 Jan-Feb;25(1):20-5. No Mean, SD reported.
(13) Glasspoole EA, Erickson RL, Davidson CL. A fluoride-releasing composite for dental applications.  Dent Mater. 2001 Mar;17(2):127-33. No SD reported.
(14) De Witte AM, De Maeyer EA, Verbeeck RM, Martens LC. Fluoride release profiles of mature restorative glass ionomer cements after fluoride application. Biomaterials. 2000 Mar;21(5):475-82. No Mean, SD reported.
(15) Preston AJ, Higham SM, Agalamanyi EA, Mair LH. Fluoride recharge of aesthetic dental materials.  J Oral Rehabil. 1999 Dec;26(12):936-40. No SD reported.
(16) Yip HK, Lam WT, Smales RJ. Fluoride release, weight loss and erosive wear of modern aesthetic restoratives. Br Dent J. 1999 Sep 11;187(5):265-70. No Mean, SD reported.
(17) Preston AJ, Mair LH, Agalamanyi EA, Higham SM.  Fluoride release from aesthetic dental materials. J Oral Rehabil. 1999 Feb;26(2):123-9. No Mean, SD reported.
(18) Verbeeck RM, De Maeyer EA, Marks LA, De Moor RJ, De Witte AM, Trimpeneers LM. Fluoride release process of (resin-modified) glass-ionomer cements versus (polyacid-modified) composite resins. Biomaterials. 1998 Mar;19(6):509-19. No Mean, SD reported.
(19) Forsten L.  Resin-modified glass ionomer cements: fluoride release and uptake.  Acta Odontol Scand. 1995 Aug;53(4):222-5. No Mean, SD reported.
(20) Tam LE, McComb D, Pulver F.  Physical properties of proprietary light-cured lining materials.  Oper Dent. 1991 Nov-Dec;16(6):210-7. No Mean, SD reported.
SD = Standard deviation; Mean = group mean values


Trials accepted:
- in vitro -
(1) Brooks ES, Miller BH, Nakajima H, Guo I.  Manipulation effects on fluoride release from chemically-cured and resin-modified glass ionomers.  Am J Dent. 1997 Jun;10(3):120-2.
(2) Robertello FJ, Coffey JP, Lynde TA, King P.  Fluoride release of glass ionomer-based luting cements in vitro. J Prosthet Dent. 1999 Aug;82(2):172-6.
(3) Gao W, Smales RJ, Gale MS.  Fluoride release/uptake from newer glass-ionomer cements used with the ART approach. Am J Dent. 2000 Aug;13(4):201-4.
(4) Musa A, Pearson GJ, Gelbier M.  In vitro investigation of fluoride ion release from four resin-modified glass polyalkenoate cements. Biomaterials. 1996 May;17(10):1019-23.
(5) Rothwell M, Anstice HM, Pearson GJ.  The uptake and release of fluoride by ion-leaching cements after exposure to toothpaste.  J Dent. 1998 Sep;26(7):591-7.
(6) Freedman R, Diefenderfer KE.  Effects of daily fluoride exposures on fluoride release by glass ionomer-based restoratives. Oper Dent. 2003 Mar-Apr;28(2):178-85.
(7) Yap AU, Tham SY, Zhu LY, Lee HK. Short-term fluoride release from various aesthetic restorative materials. Oper Dent. 2002 May-Jun;27(3):259-65.
(8) Silva KG, Pedrini D, Delbem AC, Cannon M.  Effect of pH variations in a cycling model on the properties of restorative materials. Oper Dent. 2007 Jul-Aug;32(4):328-35.
(9) Kuvvetli SS, Tuna EB, Cildir SK, Sandalli N, Gençay K. Evaluation of the fluoride release from orthodontic band cements. Am J Dent. 2006 Oct;19(5):275-8.
(10) Pedrini D, Delbem AC, de França JG, Machado Tde M.  Fluoride release by restorative materials before and after a topical application of fluoride gel.  Pesqui Odontol Bras. 2003 Apr-Jun;17(2):137-41. Epub 2003 Oct 10.
(11) Hayacibara MF, Ambrozano GM, Cury JA. Simultaneous release of fluoride and aluminum from dental materials in various immersion media. Oper Dent. 2004 Jan-Feb;29(1):16-22.
(12) Hsu HM, Huang GF, Chang HH, Wang YL, Guo MK. A continuous flow system for assessing fluoride release/uptake of fluoride-containing restorative materials. Dent Mater. 2004 Oct;20(8):740-9.
(13) Dionysopoulos P, Kotsanos N, Pataridou A.  Fluoride release and uptake by four new fluoride releasing restorative materials. J Oral Rehabil. 2003 Sep;30(9):866-72.
(14) Yap AU, Khor E, Foo SH.  Fluoride release and antibacterial properties of new-generation tooth-colored restoratives.  Oper Dent. 1999 Sep-Oct;24(5):297-305.
(15) Okuyama K, Murata Y, Pereira PN, Miguez PA, Komatsu H, Sano H.  Fluoride release and uptake by various dental materials after fluoride application. Am J Dent. 2006 Apr;19(2):123-7.
(16) Attar N, Turgut MD.  Fluoride release and uptake capacities of fluoride-releasing restorative materials. Oper Dent. 2003 Jul-Aug;28(4):395-402.
(17) Xu X, Burgess JO. Compressive strength, fluoride release and recharge of fluoride-releasing materials. Biomaterials. 2003 Jun;24(14):2451-61.
(18) Preston AJ, Agalamanyi EA, Higham SM, Mair LH. The recharge of esthetic dental restorative materials with fluoride in vitro-two years' results.  Dent Mater. 2003 Jan;19(1):32-7.
(19) Hotta M, Kawano S, Sekine I.  Direct tensile strength of visible light-cured restorative materials containing fluoride.  J Oral Rehabil. 2001 Sep;28(9):854-9.
(20) Gao W, Smales RJ.  Fluoride release/uptake of conventional and resin-modified glass ionomers, and compomers.  J Dent. 2001 May;29(4):301-6.
(21) Vermeersch G, Leloup G, Vreven J. Fluoride release from glass-ionomer cements, compomers and resin composites. J Oral Rehabil. 2001 Jan;28(1):26-32.
(22) Vieira AR, de Souza IP, Modesto A. Fluoride uptake and release by composites and glass ionomers in a high caries challenge situation.  Am J Dent. 1999 Feb;12(1):14-8.
(23) Nagamine M, Itota T, Torii Y, Irie M, Staninec M, Inoue K.  Effect of resin-modified glass ionomer cements on secondary caries.  Am J Dent. 1997 Aug;10(4):173-8.
(24) Kan KC, Messer LB, Messer HH. Variability in cytotoxicity and fluoride release of resin-modified glass-ionomer cements.  J Dent Res. 1997 Aug;76(8):1502-7.
(25) Tam LE, Chan GP, Yim D. In vitro caries inhibition effects by conventional and resin-modified glass-ionomer restorations. Oper Dent. 1997 Jan-Feb;22(1):4-14.
(16) Xu HH, Eichmiller FC, Antonucci JM, Flaim GM.  Single-crystalline ceramic whisker-reinforced carboxylic acid-resin composites with fluoride release. Oper Dent. 2000 Mar-Apr;25(2):90-7.
ANSWER:
No. Resin-modified glass-ionomers (RMGIC) appear to release more fluoride.
QUESTION:
Do conventional GICs release more fluoride than RMGIC?
Evidence - Base
Database: PubMed
What is PubMed?
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1. Literature search and review
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Search date: 17.11.2009

Search words (MeSH/Textwords/Boolean string):
"Fluorides"[Mesh] AND ("Glass Ionomer Cements"[Mesh] OR "Cermet Cements"[Mesh]) AND (("resins, plant"[MeSH Terms] OR ("resins"[All Fields] AND "plant"[All Fields]) OR "plant resins"[All Fields] OR "resin"[All Fields]) AND modified[All Fields] AND ("glass ionomer cements"[MeSH Terms] OR ("glass"[All Fields] AND "ionomer"[All Fields] AND "cements"[All Fields]) OR "glass ionomer cements"[All Fields] OR ("glass"[All Fields] AND "ionomer"[All Fields] AND "cement"[All Fields]) OR "glass ionomer cement"[All Fields])
Search strategy: PubMed search using search words, followed by reference check of included articles

Criteria for article inclusion:
1. Relevant to review question
2. Published in English language
3. 2-arm prospective longitudinal study (in-vitro, in-situ, in-vivo)

Search results:
Total number of articles found = 171
Number of articles included based on the inclusion criteria = 46 trials
Number of trials excluded after further review = 20
Number of trials accepted after further review = 26
2. Data analysis and results
6. Publication bias
3. Conclusion
The systematic literature search found 171 articles of which 46 in-vitro trials were identified to be in line with the inclusion criteria. Of these, 26 trials were traced and accepted for further review and data extraction. From the 25 reviewed trials 184 individual datasets were extracted and analysed. There was no conclusive difference found between both materials in their cumulative fluoride release. However, the fluoride release at time intervals appeared to be higher for RMGIC.
Collaborating review centre:
Universidade de São Paulo
Departmento de Ortodontia e
OdontopediatriaFaculdade
de Odontologia
Av Prof Lineu Prestes
2227 Sao Paulo
Brazil
email
The systematic literature search identified and traced 26 in-vitro trials in line with the inclusion and exclusion criteria. From these, a total of 184 independent datasets were extracted. Details of these datasets are provided in Table 1.

The trials investigated the difference between glass-ionomer cement (GIC) and resin-modified GIC (RMGIC) in cumulative fluoride release after periods of time and the fluoride release after certain time intervals.

Of the 184 datasets,  109 were combined in 35 separate meta-analyses and 75 datasets were analyses independently. Trials differed in methodological aspects. Datasets of the same outcome measure,  unit of measurement and time interval (t) were pooled for meta-analyses. Differences in the type of medium, in which the material samples were placed, were not considered. The results are presented in Table 2 (cumulative fluoride release after periods of time) and Table 3 (fluoride release after certain time intervals).
R E S U L T S:
A high volume of highly heterogeneous data was found. The comparison between both materials regarding their cumulative fluoride release showed non conclusive results, with a mix of datasets showing no differences or favoring either GIC or RMGIC. In contrast, the results of fluoride release at certain time intervals were largely in favor of RMGIC.