FujiCem 2 resin-modified glass ionomer cement: A researched review. Rmgi цемент
Циркониевые коронки/мосты: как добиться нужного цвета и надёжно фиксировать их?
Эти вопросы задал Гордону Кристенсену (DDS, MSD, PhD) один из читателей стоматологического информационного ресурса Dental Economics, и Гордон – стоматолог с большим опытом, автор курсов, основатель ряда организаций – развёрнуто ответил на оба, давая практически советы и делясь собственным опытом.Циркониевые коронки, установленные 3 года назад. Первый и второй моляры из циркония, цвет практически идеален.
Цвет циркониевых коронок
Циркониевые реставрации, отмечает Гордон, активно используются не особо давно, так что известная многим стоматологам проблема с их цветом – техник выдаёт коронку более светлую, чем надо, – скорее всего, будет решена в скором времени на уровне производителей материалов. На данном же этапе, д-р Кристенсен рекомендует:
- фотографировать зубы, которые попадут под коронки, но не распечатывать кадры, а отправлять их технику в электронном виде и просить выдать максимально близкий цвет;
- если фотографирование не даёт нужного результата, просто запрашивать коронки/мосты цветом на тон темнее, чем требуется.
Гордон указывает на тот факт, что сегодня цвет блоков циркония, из которых изготавливаются коронки, может отличаться от упаковки к упаковке вне зависимости от маркировки на них. Но проблема эта имеет временный характер.
Фиксация циркониевых коронок на цемент
Как отмечает Гордон Кристенсен, проблема с фиксацией имеет достаточное распространение, чтобы посвятить ей ряд исследований. Собственно, такими исследованиями–испытаниями и занимается одна из созданных д-ром Кристенсеном организаций, Clinicians Report Foundation (CR). На курсах Гордона многие отмечали, что циркониевые коронки и мосты просто слетают с зубов явно раньше срока. В качестве некоторых мер противодействия такому развитию событий, Кристенсен предлагает ряд рекомендаций. Все они основаны на актуальных результатах работы CR.
- Большинство стоматологов сходятся во мнении, что высота стенки такого препа от десневного края до окклюзионной поверхности должна быть не менее 4 мм, разница в высоте стенок – не более 20º по продольной оси.
- Надо ли применять бонд для улучшения качества связи композита в RMGI-цементе с зубом? Однозначного ответа на этот вопрос нет, но исследование, проводимое CR вот уже 12 лет, указывает на отсутствие такой необходимости: за этот временной промежуток потеря циркониевой коронки наблюдалась только в 4% случаев, все наблюдаемые коронки цементировались композитным стеклоиономерным цементом без бонда.
- Нужен ли праймер? То же исследование позволяет сделать вывод, что не нужен, если используется RMGI-цемент, однако при фиксации на обычный композитный цемент праймер может быть не лишним.
- В общем и целом, композитный стеклоиономерный цемент (RMGI-цемент) позволяет добиться хороших результатов при фиксации циркониевых коронок на «идеальный» преп (стенка 4 мм, расхождение не более 20º по продольной оси). Однако в будущем могут появиться более специализированные материалы.
Если преп не идеален…
Конечно, идеально препарировать под циркониевую коронку зуб получается не всегда. Порой указанные 4 мм и 20º получить не удаётся. Что делать в таких случаях? Д-р Кристенсен говорит, что многие стоматологи в подобных случаях используют композитный цемент, самоадгезивный (бондинг в составе) или обычный (бондинг наносится отдельно). Материалы, предлагаемые Гордоном как пример – RelyX Unicem 2 (3M ESPE), Maxcem Elite (Kerr Dental), Multilink Automix (Ivoclar Vivadent), Panavia (Kuraray Dental).
При этом, потеря циркониевых коронок, зафиксированных на такие цементы – явление более частое, чем потеря коронок на RMGI-цементах. Чтобы получать более надёжный результат при использовании композитных цементов, д-р Кристенсен предлагает наносить бондинг на препарированный зуб и на внутреннюю поверхность коронки. Совет основан на практическом опыте CR, но не на рекомендациях производителей цементов: Гордон с сожалением указывает на тот факт, что среди них единого мнения по этому вопросу просто нет.
Итого: фиксация циркониевой коронки/моста, шаг за шагом
Суммируя результаты проводимых CR исследований, Гордон Кристенсен предлагает следующий порядок действий при фиксации циркониевых коронок и мостов.
- Обработайте внутреннюю поверхность циркониевой коронки/моста струей песка или используйте пасту Ivoclean (Ivoclar Vivadent).
- Обработайте препарированный зуб порошком пемзы с водой, нанесите десенсибилизатор/дезинфектант (например, Gluma от Heraeus Kulzer, MicroPrime от Danville Materials) в два приёма по одной минуте, удалите его с помощью слюноотсоса, не смывайте.
- Зафиксируйте циркониевую коронку/мост RMGI-цементом.
- Обработайте внутреннюю поверхность циркониевой коронки/моста струей песка или используйте пасту Ivoclean (Ivoclar Vivadent).
- Нанесите MDP-праймер на внутреннюю поверхность коронки/моста (например, Z-Prime Plus от Bisco Inc., Monobond Plus от Ivoclar Vivadent).
- Сделайте поверхность препа более грубой (инструментальная обработка), очистите препарированный зуб порошком пемзы с водой, нанесите десенсибилизатор/дезинфектант, удалите его с помощью слюноотсоса, не смывайте.
- Нанесите бонд на внутреннюю поверхность циркониевой коронки/моста и на преп, зафиксируйте на композитный цемент.
В заключении д-р Кристенсен отмечает, что циркониевые коронки и мосты, безусловно, отличное решение для жевательных зубов, а проблемы с цветом наверняка будут решены в ближайшем будущем. В том же, что касается фиксации, приведённые выше советы основаны на исследованиях Clinicians Report Foundation и исследования эти не прекращаются, так что в следующих материалах на данную тему рекомендации могут быть расширены и дополнены.
На основе материала Cementing zirconia restorations
Поделитесь материалом с друзьями и коллегами:
Cement chemist notation - Wikipedia
Cement chemist notation (CCN) was developed to simplify the formulas cement chemists use on a daily basis. It is a shorthand way of writing the chemical formula of oxides of calcium, silicon, and various metals.
Abbreviations of oxides
The main oxides present in cement (or in glass and ceramics) are abbreviated in the following way:
Conversion of hydroxides in oxide and free water
For the sake of mass balance calculations, hydroxides present in hydrated phases found in hardened cement paste, such as in portlandite, Ca(OH)2, must first be converted into oxide and water.
To better understand the conversion process of hydroxide anions in oxide and water, it is necessary to consider the autoprotolysis of the hydroxyl anions; it implies a proton exchange between two OH−, like in a classical acid-base reaction:OH−acid 1 + OH−base 2 → O2−base 1 + h3Oacid 2
or also,2 OH− → O2− + h3O
For portlandite this gives thus the following mass balance:Ca(OH)2 → CaO + h3O
Thus portlandite can be written as CaO · h3O or CH.
Main phases in Portland cement before and after hydration
These oxides are used to build more complex compounds. The main crystalline phases described hereafter are related respectively to the composition of:
- Clinker and non-hydrated Portland cement, and;
- Hardened cement pastes obtained after hydration and cement setting.
Clinker and non-hydrated Portland cement
Four main phases are present in the clinker and in the non-hydrated Portland cement.They are formed at high temperature (1,450 °C) in the cement kiln and are the following:
The four compounds referred as C3S, C2S, C3A and C4AF are known as the main crystalline phases of Portland cement. The phase composition of a particular cement can be quantified through a complex set of calculation known as the Bogue formula.
Hydrated cement paste
Hydration products formed in hardened cement pastes (also known as HCPs) are more complicated, because many of these products have nearly the same formula and some are solid solutions with overlapping formulas. Some examples are given below:
|CH||Ca(OH)2 or CaO · h3O||Calcium hydroxide|
|C-S-H||0.6–2.0 CaO · SiO2 · 0.9–2.5 h3O, with variable composition within this range, and often also incorporating partial substitution of Al for Si||Calcium silicate hydrate|
|C-A-H||This is even more complex than C-S-H||Calcium aluminate hydrate|
|AFt||C6AS3h42, sometimes with substitution of Fe for Al, and/or CO2−3 for SO2−4||calcium trisulfoaluminate hydrate, or ettringite|
|AFm||C4ASh22, often with substitution of Fe for Al, and/or various other anions such as OH− or CO2−3 for SO2−4||Calcium monosulfoaluminate|
|C3AH6||3CaO · Al2O3 · 6 h3O||Hydrogarnet|
The hyphens in C-S-H indicate a calcium silicate hydrate phase of variable composition, while 'CSH' would indicate a calcium silicate phase, Cah3SiO4.
Use in ceramics, glass, and oxide chemistry
The cement chemist notation is not restricted to cement applications but is in fact a more general notation of oxide chemistry applicable to other domains than cement chemistry sensu stricto.
For instance, in ceramics applications, the kaolinite formula can also be written in terms of oxides, thus the corresponding formula for kaolinite,Al2Si2O5(OH)4,
isAl2O3 · 2 SiO2 · 2 h3O
or in CCNAS2h3.
Possible use of CCN in mineralogy
Although not a very developed practice in mineralogy, some chemical reactions involving silicate and oxide in the melt or in hydrothermal systems, and silicate weathering processes could also be successfully described by applying the cement chemist notation to silicate mineralogy.
An example could be the formal comparison of belite hydration and forsterite serpentinisation dealing both with the hydration of two structurally similar earth -alkaline silicates, Ca2SiO4 and Mg2SiO4, respectively.Calcium system belite hydration:
Belite2 Ca2SiO4 + water4 h3O → C-S-H phase3 CaO · 2 SiO2 · 3 h3O + portlanditeCa(OH)2
2 C2S + 4 H → C3S2h4 + CH
Forsterite2 Mg2SiO4 + water3 h3O → serpentine Mg3Si2O5(OH)4 + bruciteMg(OH)2
2 M2S + 3 H → M3S2h3 + MH
The ratio Ca/Si (C/S) and Mg/Si (M/S) decrease from 2 for the dicalcium and dimagnesium silicate reagents to 1.5 for the hydrated silicate products of the hydration reaction. In other term, the C-S-H or the serpentine are less rich in Ca and Mg respectively. This is why the reaction leads to the elimination of the excess of portlandite (Ca(OH)2) and brucite (Mg(OH)2), respectively, out of the silicate system, giving rise to the crystallization of both hydroxides as separate phases.
The rapid reaction of belite hydration in the setting of cement is formally "chemically analogue" to the slow natural hydration of forsterite (the magnesium end-member of olivine) leading to the formation of serpentine and brucite in nature. However, the kinetic of hydration of poorly crystallized artificial belite is much swifter than the slow conversion/weathering of well crystallized Mg-olivine under natural conditions.
This comparison suggests that mineralogists could probably also benefit from the concise formalism of the cement chemist notation in their works.
- Locher, Friedrich W. (2006). Cement: Principles of production and use. Düsseldorf, Germany: Verlag Bau + Technik GmbH. ISBN 3-7640-0420-7.
- Mindess, S.; Young, J.F. (1981). Concrete. Englewood, NJ, USA: Prentice-Hall. ISBN 0-13-167106-5.
FujiCem 2 resin-modified glass ionomer cement: A researched review
Randy Weiner, DMD, presents research on resin-modified glass ionomer cements and reviews GC FujiCem 2 from GC America.
A confusing part of restorative dentistry revolves around which material to use. When it comes to indirect restorations, there is no consensus as to which cement to is the most ideal. In 2005, I conduced a survey of dental schools in the United States and Canada to determine what these schools were teaching about what types of cement should be used in specific situations. I concluded that there was no agreement among the schools as to which material was appropriate for any given clinical scenario. (1) We have many products to choose from, and their numbers keep increasing as manufacturers continue to introduce new cements and improve existing ones.
An article published in the Australian Dental Journal stated that an indirect restoration must be sealed with a luting agent, the primary function of which is to fill the minute void between the tooth preparation and restoration and to mechanically lock the restoration in place to prevent dislodgement during function. (2)
Ideal properties of a dental cement include biocompatibility; caries inhibition; reduction of microleakage; physical properties that resist functional forces; insolubility; absence of postoperative sensitivity; low film thickness; extended working and setting time; ease of dispensation, mixing, cleanup, and use in general; stable bonding to the remaining tooth structure and the restorative material; radiopacity; and color stability. (3,4)
This article will review the resin-modified glass ionomer cement GC FujiCem2 from GC America.
Background: Resin-modified glass ionomer cements
Jivraj, et al., state that the resin-modified glass ionomer cement is the most frequently used cement for the cementation of well-fitting porcelain-fused-to-metal (PFM) crowns, full-cast crowns, and high-strength ceramic restorations (e.g., zirconia or aluminum core). (5) Christensen suggests that a resin-modified glass ionomer cement is the cement of choice for routine cementation of PFM and zirconia-based restorations because of its desirable characteristics. (6) He also writes that long-term studies have shown the use of a resin-modified glass ionomer cement to be sufficiently retentive for adequate tooth preparations, specifically with respect to lithium disilicate restorations. (7) A 2004 survey indicated that more than half of all porcelain-fused-to-metal crowns were cemented using a resin-modified glass ionomer cement. (8)[Native Advertisement]
Glass ionomer was developed in the early 1970s. The first of the two components is an acid-soluble calcium fluoroaluminosilicate glass, and the second is an aqueous solution of polyacrylic acid. When both components are mixed, an acid-base reaction occurs. The acid etches the surface of the glass particles, resulting in the release of calcium, aluminum, sodium, and fluoride. (9) The overall pulpal biocompatibility of glass ionomer materials has been attributed to the weak nature of the polyacrylic acid, which is unable to diffuse through the dentin due to its high molecular weight. (10)
An advantage of glass ionomers is their ability to bond with teeth. This adhesion occurs via a hydrogen bond between the carboxyl groups of the polyacrylic acid and the calcium in the tooth. Additionally, these materials have a low coefficient of thermal expansion, similar to tooth structure, which allows them to maintain a bond to tooth structure and allows for the release of fluoride to the surrounding tooth. The benefit of a low coefficient of thermal expansion is the reduction of microleakage and postoperative sensitivity. (11) The fluoride release occurs early and tapers after approximately 10 days. (7)
Fluoride release from these products causes the formation of fluorohydroxyapatite in the adjacent tooth structure, thereby making it more resistant to demineralization. (12) The fluoride release inhibits secondary caries, and fluoride is toxic to those microorganisms associated with caries. (13,14)
The fluoride that leaches out can be replaced or recharged with a neutral fluoride because an acidic one would dissolve the surface of the glass ionomer. (15) There are several vehicles that can accomplish this: toothpaste, topical fluoride application, and gels. The fluoride gel is the most effective. (16) Fluoride release from restorative materials can reduce caries, with no patient compliance required, and it's important for controlling caries in high-caries-risk patients. (17)
Resin-modified glass ionomer cements were developed to overcome the high solubility of glass ionomers. These cements bond to the inorganic dentin via a link to the calcium ion in the dentin. As with glass ionomers, this is an acid-base reaction that occurs in an aqueous environment. By combining the advantages of glass ionomer and resin, these materials also release fluoride, have an increased resistance to microleakage, adhere to tooth structure, and are less soluble than a conventional glass ionomer. (18,19) These materials have a longer working time than traditional glass ionomers. (9) Clinicians should be aware that, after the photopolymerization of the resin-modified glass ionomer is complete, the glass ionomer setting reaction continues.
The fact that the polymerization occurs prior to completion of the acid-base reaction helps decrease the solubility of these products. This makes this material more advantageous in a moist environment. Resin-modified glass ionomer cements are good for usage with restorations that have margins where crevicular fluids, salivary flow, or tongue control can present clinical challenges to the dentist in maintaining a dry field. (20)
Resin-modified glass ionomers have a chemical bond to sclerotic dentin than is stronger than the bond that results from etching dentin and placing a dentin bonding agent. (21) This is beneficial in scenarios when sclerotic dentin has been exposed because an existing restoration has been removed in preparation for an indirect restoration.
Ideally, when a preparation is made for a cast restoration, all caries would be removed. There is, however, the possibility that some caries-affected dentin will remain. Clinicians should be aware that the bond strength of a resin-modified glass ionomer cement to caries-affected dentin is higher than the bond strength of a glass ionomer to caries-affected dentin. (22)
Metal posts cemented with a resin-modified glass ionomer cement may be difficult to remove, should it be necessary to reenter the root canal system. (23) When mechanical retention is compromised, a resin-modified glass ionomer cement should be used. (23)
Some clinicians may apply a cavity disinfectant to the completed preparation. A 2009 study showed that the application of 2% chlorhexidine gluconate did not interfere with the microtensile strength of glass ionomer materials to both sound and caries-affected dentin. (24) Additionally, it was recently reported that the application of glutaraldehyde/ 2-hydroxyethylmethacrylate (HEMA) desensitizers to the preparation does not interfere with the use of a resin-modified glass ionomer as the final cementing agent. (7)
Because both glass ionomer and resin-modified glass ionomer products are water-based, clinicians should be aware of the expiration dates of the products in use. Although a product may appear clinically usable after its expiration date, its viscosity may be altered and its strength reduced.
Previously, low film thickness was mentioned as a characteristic of an ideal cement. Resin-modified glass ionomer cements are known for their low film thickness. The advantage this offers is that less material can be placed inside the casting, which can help eliminate the hydraulic issues associated with replacement of the prosthesis. (20) This can also reduce the chance of the casting not being fully seated.
Glass ionomer and resin-modified glass ionomers are available in powder-liquid, paste-paste, and encapsulated formulas. The powder-liquid versions are usually less expensive. Clinicians will find that the paste-paste products will produce equal and consistent amounts of both components (based on manufacturer research). These delivery systems also allow for easier cleanup, as do the encapsulated products that do not require hand mixing. Dentists who use a syringe delivery system that includes an automix tip will find that it is fast, easy to use, and convenient, and that it reduces the amount of air in the final mix compared to hand mixing. (25)
GC FujiCem2 is such a product. GC FujiCem has been available for many years and has enjoyed much success. The manufacturer, GC America, declares that over 150 million crowns have been cemented since the cement was introduced in 2001. In July 2012, an improved versionextexwvr of this material was introduced. GC FujiCem2, a resin-modified glass ionomer cement, is a paste-paste material (figure 1).
Clinical relevance of GC FujiCem 2
Internal research from GC America found that GC FujiCem 2 had more fluoride release after one week than other resin-modified glass ionomer cements. As with other resin-modified glass ionomer cements, the released fluoride can be replaced.
Using a resin-modified glass ionomer cement with a low film thickness would allow the casting to be properly seated. As previously stated, this characteristic would reduce hydraulic forces involved with cementation of castings. The film thickness of 10 microns is less than that of other, similar products, including GC FujiCem, so seating of castings should be easier for the clinician.
A stronger cement can improve the retention of indirect restorations. This second generation resin-modified glass ionomer has increased bond, flexural, and compressive strengths. This is due to, what has been termed, F2 Flex Fuse Technology, which incorporates high-elastic crosslinking monomers with a modified filler-surface treatment.
The flex is due to a flexible long-chain monomer that gives the material its higher flexural strength by acting like a shock absorber to resist occlusal forces, making the material suitable for all-porcelain restorations in addition to metallic-based ones. The modified filler-surface treatment creates a strong bond between the glass particles and the resin. A stronger material also translates to a reduction in the likelihood of restoration dislodgement. Clinicians should remember that glass ionomers have a chemical bond to tooth structure. On the topic of long-term proven results, according to Clinicians Report, FujiCem2 is an ideal product for use with zirconia, lithium disilicate, and metal-based crowns. (26)
There are benefits that some products have that do not directly affect the patient. One such benefit is the ease with which a product can be handled by the clinical staff. The clinician's ability to dispense and mix the material with minimal effort aids the patient indirectly because it can result in a shorter visit. GC FujiCem 2 is one of those products. It is available in an intro Kit, automix package, and a refill kit. Those dentists who mix by hand should be aware that pastes A and B have different colors; spatulation is complete when the material is homogeneous in color (light yellow). The material reaches a rubbery consistency one minute after restoration placement, allowing for a quick and easy removal of the excess material.
GC America has designed the Paste Pak system to dispense the correct amount of each paste so that the clinician has right proportions of each material.
There are two delivery systems for clinicians to choose from: the GC FujiCem 2 dispenser and the Paste Pak dispenser. The GC FujiCem 2 dispenser is 85% lighter than the metallic Paste Pak instrument. Both dispensers can be steam autoclaved, and both systems allow the operator to dispense directly into the casting (or tooth, in the case of a post-and-core restoration) via the automix tip or onto a mixing pad for hand spatulation.
Editor's Note: This article first appeared in Pearls for Your Practice: The Product Navigator. Click here to subscribe. Click here to submit a products article for consideration.
1. Weiner R. Teaching the use of liners, bases, and cements: A 10-year follow-up survey of North American dental schools. Dentistry Today. 2006;25:74–79.2. Hill EE and Lott J. A clinically focused discussion of luting materials. Aust Dent Journ. 2011;56(1 Suppl):67–76.3. Strassler HE, Coviello V. FujiCem resin-reinforced glass ionomer cement. Contemp Esthet Restorat Practice. 2001;12:1–2.4. Simon J, Darnell L. Considerations for Proper Selection of Dental Cements. Compend Contin Educ Dent. 2012;33(1):28–35.5. Jivraj SA, Reshad M, Donovan T. Selecting luting agents. Inside Dentistry. 2013;9(2):108–114.6. Christensen GJ. Ask Dr. Christensen. Dental Economics. 2008;98(5):50–54.7. Christensen G. Clinicians Report. 2013;6(4):1–3.8. Farah H. Opinions about cement. Dentaltown. 2004;5(1):56.9. Anusavice KJ. Phillip’s Science of Dental Materials. 11th ed. St. Louis, MO: Mosby Elsevier; 2003.10. Craig RG, Powers JM. Restorative Dental Materials. 12th ed. St. Louis, MO: Mosby Elsevier; 2006: 119.11. Anusavice KJ, Shen C, Rawls HR. Phillip’s Science of Dental Materials. 12th ed. St. Louis, MO: Mosby Elsevier; 2013: 322.12. Mount GJ. Minimal intervention dentistry: rationale of cavity design. Oper Dent. 2003;28:92–99.13. Forsten L. Fluoride release from a glass ionomer cement. Scand J Dent Res. 1977;85:503–504.14. Onose H. Study on the antibacterial effects of glass ionomer cement. Biocomp Dent Mat. 1977;20:130–132.15. Craig RG, Powers JM. Restorative Dental Materials. 11th ed. St. Louis, MO: Mosby Elsevier; 2002.16. Ugarte J, Lagravere MO, Revoredo JA, et al. Fluoride agent’s uptake effect over two glass ionomer cements and a resin-modified. J Dent Res. 2003;82(Spec issue B):Abstract 938.17. Burgess J. Fluoride-releasing materials and their adhesive characteristics. Compend Contin Educ Dent. 2008; 29(8):82–91.18. Simon J, de Rijk WG. Dental Cements. Inside Dentistry. 2006;2(2):42–47.19. Estafan D, Pines MS, Erakin C, et al. Microleakage of Class V restorations using two different compomer systems: an in vitro study. J Clin Dent. 1999;10:124–126.20. Lowe R. Dental cements: an overview. Dentistry Today. 2011;30(10):138–143.21. Browning MD. The benefits of glass ionomer self-adhesive materials in restorative dentistry. Compend Contin Educ Dent. 2006;27:308–314.22. Palma-Dibb RG, de Castro CG, Ramos RP, et al. Bond strength of glass-ionomer cements to caries-affected dentin. J Adhes Dent. 2003;5(1):57–62.23. Mitchell CA. Selection of materials for post cementation. Dent Update. 2000;27(7):350-354.24. Erin NK, Candan U, Aykut A, et al. No adverse effect to bonding following caries disinfection with chlorhexidine. J Dent Child. 2009;76(1):20–27.25. Fixed unit prosthesis: metal free. CRA Newsletter. 2003;27(5):1.26. Christensen G. Clinicians Report. 2015;8(6):1–2.
Randy Weiner, DMD, is a leading researcher, publisher, and lecturer on the clinical application of dental materials. Much of his work has focused on the comparative merits of liners, bases, and cements. Dr. Weiner earned his DMD at Tufts University School of Dental Medicine and subsequently achieved fellowships in the Academy of General Dentistry, Pierre Fauchard Academy, and American College of Dentists. Other professional affiliations include membership in the American Dental Association, International Association of Dental Research, American Association of Dental Schools, American Analgesia Society, and Alpha Omega Dental Fraternity. For more than a decade, Dr. Weiner served as an assistant clinical professor in the department of restorative dentistry at Tufts University School of Dental Medicine in Boston. Dr. Weiner frequently lectures and runs hands-on courses, and he practices restorative and general dentistry in Millis, Massachusetts. He resides with his wife and two daughters in nearby Ashland, Massachusetts. He can be reached via email at [email protected]
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Dental cement - Wikipedia
Dental cements are a group of materials with a wide range of Dental & Orthodontic applications. Common uses include temporary restoration of teeth, cavity linings to provide pulpal protection, sedation or insulation and cementing fixed prosthodontic appliances. 
Traditional cements are presented as separate power & liquid components, manually mixed to form a viscous liquid, which then sets to form a brittle solid after application on the required treatment surface. More advanced cements, such as GIC, can also be presented in capsule form and are mechanically mixed using rotational or oscillating mixing machines.
Ideal Cement Properties
- Non irritant - many cements are acidic and therefore an irritant to the pulp. However, on setting there is a rapid increase in pH and polycarboxylate cements are considered to be the most biocompatible of the cements due to its most rapid rise in pH.
- Provide a good marginal seal to prevent marginal leakage.
- Resistant to dissolution in saliva, or in any oral fluid - a primary cause of failure of cements is due to dissolution of the cement at the margins of a restoration.
- High strength in tension, shear and compression to resist stresses at the restoration-tooth interface.
- Adequate working and setting times.
- Good aesthetics.
- Good thermal and chemical resistance.
- Opacity - for diagnostic purposes on radiographs.
- Low film thickness (ideally 25 microns).
- Retention - if an adhesive bond can be created between the cement and the restorative material, this can greatly enhance the retention. Otherwise, the retention is governed by the geometry of the tooth preparation. [page needed]
The following table describes the properties of each type of cement in more detail:
|Cement type||Brands Available |
|Zinc phosphate||Hy-Bond Zinc Phosphate Cement (Shofu Dental) |
Modern Tenacin (L.D. Caulk)
Zinc Cement Improved (Mission White Dental)
|Long span bridges |
orcelain jacket crowns
|All-ceramic restorations - due to setting expansion |
Inadequate retention form of tooth preparation
|Highest elastic modulus |
High Compressive Strength
Low film thickness
|Acidic - possible pulpal irritation |
Lack of antibacterial action
Lack of adhesion
Low tensile strength
Provides only mechanical seal
Exothermic during set
High solubility (in oral fluids)
|Zinc polycarboxylate||Hy-Bond Polycarboxylate Cement (Shofu Dental) |
Tylok Plus (L.D. Caulk)
|Porcelain restorations |
|Titanium based restorations (cement discolouration occurs)||Antibacterial |
Adhesive to tooth structure
Sufficient compressive strength
Higher tensile strength than Zinc Phosphate
Low post-op sensitivity
|Low pH initially |
Low resistance to erosion in acidic environment
Short working time
|Glass ionomer (GI)||Fuji I (GC America) |
|Metal and Metal-Ceramic Restorations |
All Ceramic Crowns with high strength cores such as alumina or zirconia
Restoring erosion lesions
|Allergy (rare) |
Dentine close to pulp (place suitable liner first)
|Adhere to teeth and metal |
Ease of Mixing
Thermal compatible with enamel
Good resistance to acid dissolution
|Soluble in water |
Rapid set - time limitation especially in cementation of several units.
Moisture sensitivity at set
Low fracture toughness
Poor wear resistance
Possible pulpal sensitivity
|Resin modified glass ionomer (RMGI)||Fuji Plus (GC America) |
Vitremer Luting (3M/Espe)
Advance (L.D. Caulk)
Rely X Luting
|Cavity liners |
|All-ceramic crowns - due to uptake of water causing swelling and pressure on the crown |
Veneer - not retentive enough
|Dual cure |
Higher flexural strength than GI
Capable of bonding to composite materials
|Setting expansion may lead to cracking of all-ceramic crowns |
|Zinc oxide eugenol||Temp-Bond |
Fynal (L.D. Caulk)
Super EBA (Bosworth)
|Temporary crowns, bridges |
Provisional cementation of fixed partial dentures
Provisional restoration of teeth
|When resin cement to be used for permanent cementation||Neutral pH |
Good sealing ability
Resistance to marginal penetration
Obtundent effect on pulpal tissues
|Weakest of the cements |
Low abrasion resistance
Soluble (in oral fluids)
Little anticariogenic action
|Resin cements||Panavia 21 (Kurarary) |
Dual Cement (Vivadent)
Rely X Unicem (3M/Espe)
|All crown types |
Bonding fixed partial dentures
Indirect resin restorations
|If a ZOE cement has been used for the previous temporary. |
Light cured under a metal crown since it would not cure through the metal.
|Strongest of the cements - highest tensile strength. |
Least soluble (in oral fluids)
High micromechanical bonding to prepared enamel, dentin, alloys and ceramic surfaces
|Setting shrinkage - contributing to marginal leakage |
Requires a meticulous and critical technique
Possible pulpal sensitivity
Difficult to remove excess cement
Dental cements can be utilised in a variety of ways depending on the composition & mixture of the material. The following categories outline the main uses of cements in Dental procedures.
Unlike composite and amalgam restorations, cements are usually used as a temporary restorative material. This is generally due to their reduced mechanical properties which may not withstand long-term occlusal load.
Bonded Amalgam restorations
Amalgam does not bond to tooth tissue and therefore requires mechanical retention in the form of undercuts, slots and grooves. However, if insufficient tooth tissue remains after cavity preparation to provide such retentive features, a cement can be utilised to help retain the amalgam in the cavity.
Historically, zinc phosphate and polycarboxylate cements were used for this technique, however since the mid-1980s composite resins have been the material of choice due to their adhesive properties. Common resin cements utilised for bonded amalgams are RMGIC and dual-cure resin based composite.
Liners and Pulp Protection
When a cavity reaches close proximity to the pulp chamber, it is advisable to protect the pulp from further insult by placing a base or liner as a means of insulation from the definitive restoration. Cements indicated for liners and bases include:
- Zinc oxide eugenol
- Zinc polycaroxylate
Pulp capping is a method to protect the pulp chamber if the clinician suspects it may have been exposed by caries or cavity preparation. Indirect pulp caps are indicated for suspected micro-exposures whereas direct pulp caps are place on a visibly exposed pulp. In order to encourage pulpal recovery, it is important to use a sedative, non-cytotoxic material such as Setting Calcium Hydroxide cement.
Luting materials are used to cement fixed prosthodontics such as Crowns & Bridges. Luting cements are often of similar composition to restorative cements, however they usually have less filler meaning the cement is less viscous.
- Zinc Polycarboxylate cement
- Zinc oxide eugenol luting cement
Summary of clinical applications
|Clinical application||Type of cement used|
|Metal||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|Metal ceramic||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|All ceramic||Resin cement|
|Temporary crown||Zinc oxide eugenol cement|
|3/4 crown||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|Conventional||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|Resin bonded||Resin cement|
|Temporary bridge||Zinc oxide eugenol cement|
|Inlay||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|Onlay||Zinc phosphate, GI, RMGI, self or dual cured resin *|
|Post and core|
|Metal post||Any cement which is non-adhesive (NOT resin cements)|
|Fibre post||Resin cement|
|Orthodontic brackets||Resin cement|
|Orthodontic molar bands||GI, zinc polycarboxylate, composite|
Composition and classification
ISO classification Cements are classified on the basis of their components. Generally, they can be classified into categories:
- Water-based acid-base cements: zinc phosphate (Zn3(PO4)2), Zinc Polyacrylate(Polycarboxylate), glass ionomer (GIC). These contain metal oxide or silicate fillers embedded in a salt matrix.
- Non-aqueous/ oil bases acid-base cements: Zinc oxide eugenol and Non-eugenol zinc oxide. These contain metal oxide fillers embedded in a metal salt matrix.
- Resin-based: Acrylate or methacrylate resin cements, including the latest generation of self-adhesive resin cements that contain silicate or other types of fillers in an organic resin matrix.
Cements can be classified based on the type of their matrix:
These cements are resin based composites. They are commonly used to definitively cement indirect restorations, especially resin bonded bridges and ceramic or indirect composite restorations, to the tooth tissue. They are usually used in conjunction with a bonding agent as they have no ability to bond to the tooth, although there are some products that can be applied directly to the tooth (self-etching products).
There are 3 main resin based cements;
- Light-cured - required a curing lamp to complete set
- Dual-cured - can be light cured at the restoration margins but chemically cure in areas that the curing lamp cannot penetrate
- Self-etch - these etch the tooth surface and do not require an intermediate bonding agent
Resin cements come in a range of shades to improve aesthetics.
Zinc Polycarboxylate Cements
- Powder + liquid reaction
- Zinc oxide (powder) + poly(acrylic) acid (liquid)= Zinc polycarboxylate
- Zinc polycarboxylate is also sometimes referred to as zinc polyacrylate or zinc polyalkenoate
- Components of the powder include zinc oxide, Stannous fluoride, magnesium oxide, silica and also alumina
- Components of the liquid include poly(acrylic) acid, itaconic acid and maleic acid.
- Zinc polycarboxylate cements adhere to enamel and dentine by means of chelation reaction.
Indications for use:
- Temporary restorations
- Inflamed pulp
- Cementation of crowns
|Bonds to tooth tissue or restorative material||Difficult to mix|
|Long term durability||Opaque|
|Acceptable mechanical properties||Soluble in moth particularly where stannous fluoride is incorporated in the powder|
|Relatively inexpensive||Difficult to manipulate|
|Long and successful track record||ill-defined set|
Known contra-indications of dental cements
Dental materials such as filling and orthodontic instruments must satisfy biocompatibility requirements as they will be in the oral cavity for a long period of time. Some dental cements can contain chemicals that may induce allergic reactions on various tissues in the oral cavity. Common allergic reactions include stomatitis/dermatitis, uticaria, swelling, rash and rhinorrhea. These may predispose to life threatening conditions such as anaphylaxis, oedema and cardiac arrhythmias.
Eugenol is widely used in dentistry for different applications including impression pastes, periodontal dressings, cements, filling materials, endodontic sealers and dry socket dressings. Zinc oxide eugenol is a cement commonly used for provisional restorations and root canal obturation. Although classified as non-cariogenic by the Food and Drug Administration, eugenol is proven to be cytotoxic with the risk of anaphylactic reactions in certain patients.
Zinc oxide eugenol constituents a mixture of zinc oxide and eugenol to form a polymerised eugenol cement. The setting reaction produces an end product called zinc eugenolate which readily hydrolyses producing free eugenol that causes adverse effects on fibroblast and osteoclast-like cells. At high concentrations localised necrosis and reduced healing occurs whereas for low concentrations contact dermatitis is the common clinical manifestation.
Allergy contact dermatitis has been proven to be the highest clinical occurrence usually localised to soft tissues with buccal mucosa being the most prevalent. Normally a patch test done by dermatologists will be used to diagnose the condition. Glass Ionomer cements have been used to substitute zinc oxide eugenol cements (thus removing the allergen), with positive outcome from patients.
3. Acid-base Cements (1993) A. D. Wilson and J.W. Nicholson