Operative Dentistry

Resin-modifíed glass-ionomer cement restoration of posterior teethwith proximal carious lesions

Jean-Michel Morand*/Pierre Jonas**

Remarkable improvemeiUs in ihe early deteciioii of proximal lesions and ¡he deveiopmen!of new restoralive materials warrant a reassessment of traditional cavit}- design. A protocoithat utilizes a new cavity design in conjunction with resin-modißed glass-ionomer cementsto treat proximal carious lesions is described. (Quintessence Int 199.x-26:389-394.)

Introduction

The development of adhesive dentistry and the avail-abiiity of reliable new dental materials, such as dentinaladhesives and glass-ionomer cements, have changedthe daily practice of dentistry, because these advanceshave led to more conservative cavity design. The mainpurpose of snch conservative cavity preparation is thepreservation of sound dental tissue.

Although conservative cavity preparations havelong been imagined, it was the development ofresin-modified glass-ionomer cements that have al-lowed the modified minimal designs. Resin-modifiedglass-ionomer cements possess the following impor-tant properties:'"'

• Improved physic o chemical adhesion to dental tis-sues (compared to conventional glass-ionomercements)

• Fluoride ion release that gives the material anti-cariogenic properties

• CoefTicient of thermal expansion close to that ofdentin, thereby providing good dimensional stabiiityto the restoration

• Excellent biocompatibility and adequate pulpaltolerance

• Sufficient radiopacity for postoperative examina-tions

• Wide range of shades• For some brands, easier and more predictable

handling because of predosed, encapsulated form

Because of these technical improvements and thetools available for early caries detection, a moreconservative means of treating proximal lesions cannow be recommended.

Technique (Figs 1 to 12)

The cavity is opened from the lingual and buccalsurfaces; the occlusal surface remains untouched.Previous reports have mentioned this approach in thepast,'"" but mechanical factors and the limits ofthematerials then on the market restrained these Initialefforts. The goals achievable today are (!) totalremoval of carious tissues; (2) maximal preservationand strengthening of hard tissue through microcavitypreparation and marginal ridge preservation (destruc-tion of the marginal ridge is often the main factorimplicated in the recurrent pathoses associated withtraditional restorations; and (3) insertion of an adhe-sive and fluoride-releasing material to prevent any riskof recurrent caries.

' Private Practice, Pédiatrie Dentistry. Paris, France; Head of PédiatrieDentistry, American Hospital of Paris, Neuilly, France; AssociateClinical Professor, Oral Heaith Praetice, University of Kentucky,College of Dentistry, Lexington. Kentucky,

" Private Practice. Jouy-en-Josas, France: Attache de Recherche,Laboratoire des Biomateriaux, université Paris Vil, Paris, France.

ReprÍDtreqiiestS:DrJ.-M, Moratid, 10 rue Le Sueur. 75116 Paris. France.

Discussion

Proper application of the technique is dependent onwell-defined selection criteria. Precise diagnosisshould be established early with definite objectivefindings. Clinical observation should include fiber-

iILW IIiltllliailüngí VÔlUrtlS^6>>lumber 6/1995 389

Operative Dentistry

Fig 1 Access to the cavity is achieved from Ihe lingual andthe buooal directions. The bur is oriented cervically tomaintain suflicienl heighl and strength of the marginalridge.

Fig 2 A wooden wedge is inserted to open the space andprevent rubber dam entrapment during the procedure. ANo. 4 carbide bur is recommended for preparing the toothand removing oaries.

Fig 3 The mesiai wing oi the clamp has been redesignedto allow correct orientation of the handpieoe during bucco-linguai opening of the cavity.

Fig 4 The procedure is simplified when two adiacentproximal iesions are present.

Fig 5 The matrix band is deliberaleiy kept loose to allowinjection of the material from a syringe with a CentrixNeedletube {Centrix].

Fig 6 Once the cement can be seen flowing from theopposite side of the preparation, the matrix is tightened tocompress the material. Light curing is initiated from theocolusal direction for 40 seconds.

390 Quintessence International Volume 26. Numhe

Operative Dentistry

Fig 7 Prior to rubber dam removal, a protective sealant isapplied with a brush. The sealant is gentiy air blown to flowon the proximai restoration, Fioss is inserted between theteeth before light curing.

Figs 8 and 9 A proximal cavity is prepared on the distal aspect of the primary mandibular second molar (lingual view].

Fig 8 Fig 9

Figs 10 and 11 Proximal lesions on this permanent mandibular premolar have been restored with proximal preparations toavoid unnecessary removal of sound denial tissue. The preparations were obturated with Fu|i II LC light-cured glass-ionomercement (GO.

Fig 10 Fig 11

Quintes Mm(^ Number 6/1995 391

operative Dentistry

Fig 12 (!op) Proximal lesions were detected on the firstpermanent molar and the second premolar in 1990 andrestored according to the described technique. The patientwas instructed to floss. Daily fluoride mouthrinse wasprescribed to remineraliza the initial lesions noticed be-tween the first and second premolars, (center) Instructionswere not followed regularly. A control bitewing radiographtaken in 1992 showed progression ot these lesions, whichwere then restored (boltorn) The control radiograph takenin 1994 shows the restorations in place with minimal toothloss.

optic trans illumination of the site inyolved, andbitewing radiographs should be taken to confirm thepresence of a lesion. '' The damage that could resultfrom forceful probing of demineralized intact enamel iswell documented and should be avoided.'^

There is a difference between the radiographieimage of a lesion and its clinical and histologie reality.Therefore any decision to open the tooth shouldconsider the dental status of the patient, includingdaily hygiene practices, fluoride availability, cariessusceptibility, diet, and recall intervals.''' Too often inthe past, a wait-and-see attitude was adopted, until thepatient would ultimately show up some time later withpulpa] involvement.'- Because it is also known todaythat fluoride can remineralize the initial decalcifiedlesion before cavitation takes place when propermotivation and regular professional monitoring are

ensured,'* no one plan will meet every patient's needs.When indicated, early interception of the cariousprocess will allow minimal intervention that will notinitiate the cycle of recurrent pathoses that result fromwell-intended but often iatrogenic procedures.

This solution is not indicated when the cariousprocess has led to considerable destruction of dentaltissue that risks the integrity of the marginal ridge.Wilson and McLean" precisely defined the prerequi-sites for marginal ridge preservation in their descrip-tion of the tunnel restoration. They concede that thesecavities require a rather large opening of the occlusalsurface and consequently cannot be considered asbeing economical of tooth substance; however, theirrecommendations for the preservation of the marginalridge remain valid to assure good resistance to thefacial slot restoration." More recently, some authorshave questioned the efficacy of this technique in theremoval of cades'* as well as the vahdity of the dentalstructure-preserving assumption attached to this ap-proach, "

Optical aids are required, and binoculars with x 2.5or X 3.5 magnification are essential. With these tools,buccal and lingual opening of the preparation issufficient for complete viewing of the cavity and totalremoval of carious tissues.

For the past 15 years, dental research has shown theadvantages of the glass-ionomer cements. It is impor-tant to understand their properties and to know theirlimitations, howeyer, to obtain the most benefit fromtheir use. Resin-modified glass-ionomer cements ben-efit from qualities already present in the traditionalautocured glass-ionomer cements. However, theirtechnology has resulted in an improvement in severalclinically releyant mechanical properties:

1. Tensile diametral strength has increased to 30 MPa(13 MPa for autocured cements) and compressivestrength to 170 MPa. (Metal-modified cermets hadonly reached 140 MPa in the past.)^**-'

2. Adhesive properties to both enamel and dentin areimproved.

3. Better esthetics result from better transparency withnatural tooth structure and the availability ofmultiple shades.

4. After 20 seconds of light curing, the water sensi-tivity is almost eliminated, allowing immediatepolishing of the restoration.-^

5. Placement is easier and faster because of thelight-command initial polymerization.

392 Quintessence Intemational Volume 26, Number

Operative Dentistry

6. Adequate radiopacity permits the radiographieexamination of the restoration. One of the materialson the market is not radiopaque and therefore wasnot used in this protocol.

Some guidelines musi be followed to obtain the bestresults with the material. After all infected dentin hasbeen carefijlly eliminated firom the lesion, it is neces-sary to remove the smear layer for proper adhesion ofthe material to dentin. The preparation is flooded witha 10"̂ polyacrylic acid for 15 seconds; it is thenthoroughly rinsed for abont 30 seconds to obtainproper cleansing of all debris. Some materials requirethe application of a light-cured primer. Photopoly-merization of the primer may not always be easy toachieve in some areas that are less accessible to light;therefore use of these materials may be more difficultwhen this technique is used.

Placement of the material with a syringe is recom-mended to avoid incorporation of air bubbles orformation of voids. The cement is then injected rapidlyinto the cavity, because setting of the material beginsshortly after mixing, and proper reaction of the materialwith the calcium ions of the dentin is better obtained atthe early stage of the setting reaction. Because access tothese cavities is limited, endodontic needle tips can bevery usefial for delivery of the material into the cavity.

When the cavity is completely obturated, the matrixband is tightened and squeezed against the tooth tocompress the material and increase its density, en-suring improved mechanical properties. Celluloidtransparent matrix bands appear to be ideal. Unfor-tunately, they tend to flaften when tightened on atooth, and preservation of the natural concave shape ofthe tooth is compromised. Stainless steel matrix bandsare easier to manipulate in this respect. However, alonger light exposure of at least 40 seconds from theocclusal direction, followed by additional buccal andlingual exposures of 20 seconds each after the band isremoved, is then necessary because of the light-obstructing nature of the metal. Excess material iscarefLiliy removed from the tooth with resin compo-site-polishing burs and abrasive disks and strips.

Although resin-modified glass-ionomer cementsare much less sensitive to initial water contaminationthan are traditional glass-ionomer cements, theirchetnical reaction will continue for about 9 minutes,and protection is advisable during this time. Adhesionto dentin and enamel is increased and develops morerapidly when a protective varnish or a sealant isapplied to the material surface after completion of therestoration.'''^•'

Conclusion

The technique of using glass-ionomer cement toreslore posterior teeth with proximal carious lesionshas limitations imposed by diagnostic findings and theproperties of the cement. Once these factors areunderstood, the technique brings an interesting solu-tion to nil the needs of today's dentistry. A minimadentistry refers to cavity preparation limited to thecarious lesion with maximum respect for healthy tissue,to ensure that the restored tooth enjoys a considerablygreater longevity than would be provided by traditionalrestorative techniques. Recent advances allow today'spracthioner to consolidate rather than to obturate, toreinforce without weakening, and to prevent, therebyavoiding unneeded mechanical intervention.

Acknowledgments

The authors wish to express their gratitude to Dr S. R. Koenigsberg forhis precious help in reviewing the English text of this article.

References

1. Ishira Y, Tosaki S. Comparison of physical properties betweenconventionai and iight-eured type glass ionomer cement. Presentedat the P-017 Second International Congress on Dental Materials.1-4 November 1994, Honolulu, Hawaii.

2. Mathis RS. Ferracane JL. Properties of glass ionomer/resin-composite hybrid material. Dent Mater 1989i5:33S-358.

3. Andren NA, Burgess JO. Norling BK. Mechanical properties ofglass lonomerspolymerized with and without light [abstract 12441. JDent Res I993;72.1259.

Mount OJ. An Atlas of Glass-lonoMartin Dunitz, 1994:94-122.

ed 2. London;

5. Wilson AD. Nicholson JW. Acid-Base Ccments-Their Biomédicaland Industrial Applications, Cambridge University Press, 1993:169-175.

6. Mitra SB. Fluoride release from a liyht-cured elass-ionomerliner-base. J Dent Res 1991-70:75-78.

7. Kupietzky A, Houpt M, Mellberg J, Shey Z. Fluoride exchange fromglass ionomer preventive restorations. Pediatr Dent 1994:16:340-345,

S. Katsuyama S, Nogami I, Hirota K. Light-cured restorative glass-Lonomer cement. In: Katsuyama, Ishikawa, Fujii (eds). Glass-loromer Dental Cement-The Materials and Their Clinical Lise. StLouis, Ishiyaku Euroamerica, 1993:166-177.

9, Loyola-Rodnguez J, Garcia-Godoy F, Lindquist Rt. Growthinhibition of glass ionomer cements on mutans streptococci. PediatrDent 1994:16:346-349.

10. NoarSJ, Sniith BGN. Diagnosis of caries and treatment decisions inproximal surfaces of posterior teeth in vitro. J Oral Rehabill990il7:209-2l8.

11, Roggenkamp CL, Cochran MA, Lund MR. Tlie facial slot prepara-tion: A nonoccluia] option for Class 2 carious lesions. Oper Denl1982:7:102-106.

li ilci i mliùi lal -WIUI MH-¿8,'Number 6/1995 393

operative Dentistry

i:. Verdonschot EH, van de Rijke JM, Brotiwer W, ten liosch JJ, TriiinGJ, Optical quantification anil radiographie diagnosis of mcipientptosimal caries lesions. Caries Rus I9yi;25,359-364,

n , Espelid I, Radiographic diagnoses and treatment decisions onproximal caries, Cummunity Dent Oral Epidemiol I986;I4;265,

1-1, Anderson MH, Bales DJ, Oninell KA. Mudem management ofdental caries: Tlie cutting edge is not the dontiil bur. J Am DentAssoc I993i 124:36-44,

15. Bader JD, Brown J I'. Dilemtïias in caries diagnosis, J Am Dent Asoc

16, Ceiger AM, Gotelick L, Owinnett AJ, Benson BJ, Reducing whitespot lesions in orthodontic populations with fluoride nnsinj;. Am JOrthod Dentofacial Orthop I992:10h405-407.

17 Wilson AD. McLean JW. Glass-kinumcr Comiint, Chicago: Quintes-sence. 1988:197-220,

18, Papa J, Cain C, Messer HH, EtVieacy of tunnel restorations in theremoval of caries. Quimessence Int 1993:24:715-719,

19, Papa J, Cain C. IMesser HH, Wilson PR, Tunnel restoratiorts versusClass II restorations for small proximal lesions: A comparison oftooth strengths. Quintessence Int 1993:24:93-98,

20, Cattani-Lorente MA, Godin G, Meyer JM, Mechanical behavior ofglass ionomer cements affected by long-term storage in water. DentMater 1994:10:37-44,

21, Nicholson JW, Anstice HM, McLean JW, A preliitiinary report onthe effect of storage in water on the properties of commercialiighl-cured glass-ionomer cements, Br Dent J 199 2; 173:98,

22, Anstice HM, Nichoison JM, Study on tlie effect of storage indifferent media on Fuji II LC—A light-cured restorative glass-ionomer cement |abslract|. Presented at the Fourth World Bio-materials Congress, Berlin Í992:S4,

23, Hotta M, Hirukawe H, Yamamoto K, Effect of coating materials onrestorative glass ionomer cement surface, Oper Dent 1992,17:57-61. D

394

Aesthetic Designfor Ceramic Restoratioiis

The mostnatural,

esthetic resultsin dentalceramics canbe achievedwith contem-

porary techniques—and this hook describeshow. Investigated are the characteristics ofnatural dentition, tissue management, impres-sions, occlnsal records, waxing techniques,color, and lahorator\' techniques, includingmethods for an aesthetic ceramic margin,opalescence, and developtnent of the dentinemamelon. Filled with practical tips, this hookis ideal for dentists and technicians.

US$78159 pages; 292 color illus; ISBN 1-85097-034-3

Contents1 Studies of Nacural Dentition

2 Dentist-Technician-Patient Communication

3 Tissue Management for Aestheticand Biological Harmony

4 Impres,iions and Occlusal Records

5 Aesthetic Wax Diagnostic Control

6 Accurate Registration a.nd Communicationof Colour Characteristics

7 Advanced Lahoratoiy Techniques8 Case Studies

quinlc/renccbook/

Order Now

Tbllfree 1-S00-62I-0387Fax 708 682-3288

Quintessence Publishing Co, Inc