This te ch n iq u e using acid e tching and com posite restorative m aterial can be successful fo r p ro vid in g an in term ediate restoration fo r teeth affected by enam el hypoplasia.

Acid etch and enamel bond composite restoration of permanent anterior teeth affected by enamel hypoplasia John R. Mink,

DDS, MS

Susan A. McEvoy,

DMD, MS, L e x in g to n , Ky

Enam el hypoplasia is the incom plete or defective form ation of the enam el of the teeth. T here are many causes of enamel hypoplasia, as well as a wide variation in clinical appearance. In mild cases that may need little or no attention, there may only be a few small pits or grooves in the enamel. In m ore severe conditions, large por­ tions o f the enam el m ay be absent. Because the dentin is often unprotected, these teeth can be sensitive to changes in tem perature and this may cause discom fort when children eat or drink or play in cold w eather. Teeth with hy­ poplastic defects are often m ore difficult to keep clean; it is not uncom m on for these defects to becom e stained or carious. Patients, especially children, with hypoplastic anterior teeth often are concerned with their appearance and the con­ dition may affect the way they smile and their personality. H ypoplastic perm anent anterior teeth have been restored using resins, silicate cem ents, open-face steel crow ns filled with acrylic resin or silicate cem ent, and jack e t and porcelain veneer crow ns. T his paper discusses an interm ediate restorative technique that enables the patient to

be satisfied with the appearance of his teeth until a m ore perm anent restoration can be m ade. We have used the technique for several years; it is based on the use o f acid etching and com posite restorative m aterials.

T e c h n iq u e fo r re s to rin g h y p o p la s tic te e th

Local anesthesia is not usually necessary. O cca­ sionally, if it is not used, the patient may notice som e sensitivity w hen the acid is placed on the tooth if the dentin is not protected, but the dis­ com fort is slight. H ow ever, local anesthesia is indicated for caries rem oval and for treatm ent of extrem ely sensitive teeth. It is im portant to determ ine the shade of the restoration before the rubber dam is placed (or the teeth will dehydrate and lighten in shade). Lighter shades are m ost com m only used for young perm anent teeth. A layer of calcium hy­ droxide m ay be used to m ask the darkly stained dentin before placem ent of the restorative m ater­ ials. JADA, Vol. 94, February 1977 ■ 305

Because m oisture contam ination is the most com m on cause of failure of a restoration in a tooth that has been acid etched, a dry field is nec­ essary. Proper rubber dam isolation results in the highest degree of m oisture control. ■ Cavity preparation: T he aim of cavity prep­ aration (Fig 1, 2) is to clean the hypoplastic defect w ithout unnecessary removal of sound tooth structure. Pitted or stained defects confined to the enamel usually can be cleaned with a mois­ tened flour of pum ice on a brush. Do not use a pum ice or prophylaxis paste containing fluoride; we have found that this will reduce the tooth’s susceptibility to later etching. Pits or stains that are resistant to cleaning with pum ice can be re­ moved with a round bur rotating at a slow speed. T he round bur also is used to remove caries and prepare the cavity outline. Size and shape of the enamel defect and the extent of the caries dic­ tate the outline form of the preparation. It is not necessary to establish retentive points, grooves, undercuts, or parallel walls in the preparation. Internally, the finished preparation looks more like a saucer. T he irregular outline form of the defect, in addition to the acid etching of the en­ amel, contribute to the retention of the restora-

tion. F o r larger defects that have few outline ir­ regularities, consider scalloping of the enamel margins to gain additional retention and more enamel surface for bonding. Since the retention of the restoration primarily depends on the am ount of enamel surface available for etching, the enamel should not be rem oved unnecessar­ ily. A calcium hydroxide liner or base should be placed over cut dentinal tubules (Fig 3). ■ E nam el etching1'7: A solution of 35% phos­ phoric acid is used to etch the enamel margins. A small brush or cotton pellet is used to apply the acid to the enamel surface in the cavity prepara­ tion as well as to a 1- to 3-mm width of enamel surface around the preparation. T he area is kept moist with the acid solution for one to tw o min­ utes. F o r teeth that have been exposed to a fluor­ ide paste, it may be necessary to etch the enamel surface for a longer time. T he teeth are rinsed thoroughly with w ater to rem ove the acid and debris; then they are dried with a stream of air. T he dried enamel surface should appear very white (frosty or chalky) when com pared with the nonetched adjacent enamel (Fig 3). It is im­ portant that the teeth are not contam inated with w ater or saliva after the enamel surface has been acid etched. T he presence of m oisture and de­ bris, as well as the possibility of recalcification, can reduce the retention value of etching.

more severe defects on lateral Incisors.

■ Restoration o f the tooth: A layer of an enamel bonding agent is applied to the cavity preparation and the chalky-appearing etched enamel surface (Fig 4a). T he enamel bonding agent forms a me­ chanical lock with the enamel by penetrating the pits and crevices created by the acid. T he restorative m aterial is then inserted into the cavity preparation. Enough m aterial is added to overcontour the restoration onto the previous-

Fig 2 ■ Cavity preparations of hypoplastic defects. Size and shape

Fig 3 ■ Pulp protection fo r lateral incisors with calcium hydrox­

of defect dictate outline form of cavity preparation.

ide and com pleted etching of enamel surrounding all defects.

Fig 1 ■ Typical defects associated w ith enamel hypoplasia. Small pits and grooves on maxillary central Incisors and larger,

306 ■ JADA, Vol. 94, February 1977

posite surface. I f necessary, the entire proce­ dure may be repeated.

S u m m a ry

Fig 4 ■ a. Layer of enamel bonding agent applied to cavity prep­ aration and surrounding etched enamel; b, Restoration inserted and finished to etched margins of cavity preparation; c, Layer of

We have found that this procedure, using acid etching, can be very successful for providing an interm ediate restoration o f teeth disfigured by enamel hypoplasia. T he technique is easy, rela­ tively inexpensive for the patient, and quite ef­ fective for improving the appearance of the tooth.

enamel bonding agent applied to finished restoration.

ly etched and enam el-bond-treated surface around the cavity preparation (Fig 4b). T he re­ storative material forms a chemical bond with the corresponding bonding agent. R eduction of the restorative material can be m ade with high-speed burs and com posite finish­ ing disks and strips. D o not rem ove the com­ posite material down to the margin of the prep­ aration. Overlap of the restoration onto the etched margins of the preparation is necessary for retention. Since finishing of the com posite restoration can produce a rough surface, a sm ooth surface is achieved by applying a finish­ ing coat of the enamel bond agent (Fig 4c). ■ Repairing the restoration: If some of the com posite material becom es lost or discolored, new m aterial can be added to the original com ­

Dr. Mink is assistant dean for academic and clinical affairs and professor In the department of pedodontics at the University of Kentucky, College of Dentistry, Lexington, 40506. Dr. McEvoy is assistant professor in the department of pedodontics. Address requests for reprints to Dr. Mink. 1. Buonocore, M.G.; Matsui, A.; and Gwinnett, A.J. Penetration of resin dental materials into enamel surfaces with reference to bonding. Arch Oral Biol 13:61 Jan 1968. 2. Gwinnett, A.J. The bonding of sealants to enamel. J Am Soc Prev Dent 3:21 Jan-Feb 1973. 3. Gwinnett, A.J., and Matsui, A. A study of enamel adhesives. The physical relationship between enamel and adhesive. Arch Oral Biol 12:1615 Dec 1967. 4. Laswell, H.R.; Welk, D.A.; and Regenos, J.W. Attachment of resin restorations to acid pretreated enamel. JADA 82:558 March 1971. 5. Lee, B.D.; Phillips, R.W.; and Swartz, M.L. The influence of phosphoric acid etching on retention of acrylic resin to bovine enamel. JADA 82:1381 June 1971. 6. McLundie, A.C., and Messer, J.G. Acid etch incisal restora­ tive materials— a comparison. Br Dent J 138:137 Feb 18,1975. 7. Macchi, R.L., and Craig, R.G. Physical and mechanical prop­ erties of composite restorative materials. JADA 78:328 Feb 1969.

Mink— McEvoy: RESTORATION OF HYPOPLASTIC TEETH ■ 307

Acid etch and enamel bond composite restoration of permanent anterior teeth affected by enamel hypoplasia.

This te ch n iq u e using acid e tching and com posite restorative m aterial can be successful fo r p ro vid in g an in term ediate restoration fo r t...
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