Radiographic detection of recurrent carious lesions associated with composite restorations Taeko Goshima, DMD, and Yota Goshima, DDS. PhD, Tokyo, Japan TOKAI



The greatest potential problem associated with posterior composite restoration is secondary caries detection. It is essential that secondary caries is detected as early as possible to enhance the prognosis for a successful treatment outcome. This laboratory study evaluated the optimum level of radiopacity of composite materials for radiographic detection of secondary carious lesions associated with composite materials. Results indicated that for the radiologic detection of secondary caries, it is sufficient for composite materials to have the same level of radiopacity as enamel. (ORAL SURC ORAL MED ORAL PATHOL 1990;70:236-9)


adiographic interpretation of secondary carious lesions is aided if the restorative material present is radiopaque.’ Composite materials are now in widespread use for posterior teeth, replacing amalgam, because they have the advantages of being free of mercury, resistant to corrosion, and thermally nonconductive.* In spite of significant improvements in physical and chemical characteristics, however, secondary dental caries and wear resistance are still major concerns.’ Once detected clinically or radiographically, caries under a composite restoration can breach the pulpal chamber in as little as 6 to 8 months.4 In comparison, the same caries under an amalgam restoration wll take considerably longer to travel the same distance.4 Stanford and coworkers5 reported that composite materials are usually more radiopaque than dentin, but not necessarily more radiopaque than enamel. Previous investigations with respect to the radiopacity of dental composite materials have reviewed a number of current products with radiopacity in excess of that shown by enamel. They concluded that it is best for caries detection if composite materials have a higher degree of radiopacity than ename1.6y7Nevertheless, it should be remembered that excessradiopacity, as in amalgam and other metallic restorative 7/16/19793 236


--A “B

A . . . RESTORATION B.... DEFECT Fig, 1. Diagram of tooth with simulated secondary caries adjacent and lingual to restoration.

materials, can interfere with the detection of voids and recurrent caries. This is probably dependent on the angulation of the X-ray beam superimposing such metallic restorations over carious (or potentially carious) tooth structure. In 1986, Tveit and Espelid stated that secondary dental caries adjacent to a composite restoration of moderate radiopacity is easier to detect on bitewing radiographs than caries next to an amalgam restoration8 and that a 1O-degreepositive angulation of the beam plus gave the best diagnostic image.9 However, this study was limited as it compared only one composite material (P-30) to


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detection of recurrent caries


Fig. 2. Radiographs of test teeth. A, Radiopaque composite (P-30) fillings. B, Radiopaque composite (P30) with defect (1 .O mm). C, Radiopaque composite (P-30) with defect (1.6 mm). D, Radiopaque composite (Occlusin). E, Radiopaque composite (Occlusin) with defect (1 .O mm). F, Radiopaque composite (Occlusin) with defect (1.6 mm).

amalgam. In a previous investigation,” we evaluated the optimum level of radiopacity of posterior composite restorative materials compatible with radiographic interpretation. We simulated caries by making groovesof increasing depth in aluminum blocks of a thickness equivalent in radiopacity to enamel and assessedthe detectability of the caries beneath differing thicknesses of three representative composite resins. Unlike the other researchers, we suggested that composite materials with a radiopacity similar to enamel are best for the detection of secondary carious lesions and recurrent caries. The purpose of this study was to further determine the radiographic detectability of carious lesions associated with composite restoration in conventional clinical settings. MATERIAL


Two composite materials that are designed for use in posterior teeth and that are light cured under normal circumstances, P-30 (3M, St. Paul, Minnesota) and Occlusin (ICI Dental, Macclesfield, United Kingdom), were studied. The radiopacity of P-30 is that of enamel, whereas that of Occlusin is greater.‘O Five normal premolars that had been stored in 2%

QQQ Fig.

3. Example of an evaluator’s diagram.

benzalkonium chloride since the time of their extraction were selectedfor the study and radiographed with a Rex dental unit (Yoshida Co., Tokyo, Japan), at 60 kVp, 10 mA, and 0.3 seconds,with a target-to-object distance of 30 cm, with a total filtration of 2 mm Al, and Kodak Ektaspeed films (Eastman Kodak Co., Rochester, New York). The teeth were placed into a device that made it possible to obtain identical repeat radiographs. All radiographs were processedby means


Goshima and Goshima


I. Incorrect diagnosis of simulated secondary caries under composite resin restorations


Material P-30


1.O mm defect Evaluator


1 2 3 4 5 6 7 8 9 10 Total

0 0 0 0 1 2 0 0 0 1 41100

% 0 0 0 0 10 20 0 0 0 10 4 kO.lSSE

1.6 mm defect

1.O mm defect




0 0 0 0 2 1 2 1 0 0 61100

0 0 0 0 20 10 20 10 0 0 6 + 0.28SE

0 0 0 0 1 3 2 0 0 0 61100

76 0 0 0 0 10 30 20 0 0 0 6 t0.28SE

1.6 mm defect n


0 0 0 0 1 3 2 1 0 0 7/100

0 0 0 0 IO 30 20 10 0 0 1 -+0.32SE

n = No. of incorrect. % = % incorrect (mean)

of an Insta Fix processingunit (Microcopy, Newbury Park, California). The processing chemicals were prepared and used according to the manufacturer’s directions. Uniform image density was obtained by adjusting exposure times based on measurements with the use of an aluminum step-wedgeand a PDA15 densitometer (Konica Co., Tokyo, Japan). Next, class II cavity preparations were made in each tooth. P-30 was placed into the preparation, but not polymerized, to allow for easysubsequentremoval and replacement by Occlusin. Radiographs were then made with the use of the same factors and device. After the radiographs were made, the P-30 was removed and the cavity preparation cleaned with 95% alcohol. Occlusin was then placed into the preparation, not polymerized, and the above procedures repeated. With the aid of a 1.Omm diameter jet carbide bur, a simulated carious lesion was placed adjacent to the cavity preparation, on the lingual side (Fig. 1). The simulated lesion was then sealed with red wax, the radiopacity of which is negligible. P-30 was then placed into the preparation and the procedures, including radiographs, removal of P-30, and placement of Occlusin as described above, were repeated. After the radiographs of the Occlusin were made, the material was removed as above, and the simulated carious lesion was enlarged from 1.Omm to 1.6 mm. Radiographs of each tooth were taken in the following order: (a) the normal tooth without restoration,

(b) with cavity preparation restored by meansof each of the composite materials, and (c) the tooth with a defect (1 .Oand 1.6 mm, respectively) associatedwith restoration. Examples of radiographs of the teeth used are shown in Fig. 2. The above procedures were repeated for both P-30 and Occlusin and were reviewed by 10 dentists with from 5 to 10 years of experience in practice. Three were full-time faculty members of the Department of Oral Radiology, one was a full-time faculty member of the Department of Oral Surgery, one was a full-time faculty member of the Department of Restorative Dentistry at the School of Dental Medicine at Tsurumi University, three were general practitioners, and two were specialist prosthodontists in private practice. The investigators did not perform the evaluation of the radiographs. This was to assure impartiality. (Note: In Japan, there is no board of specialty as there is in the United States.) Each evaluator was given four different sets of 10 radiographs (thus a total of 40 each). Each group of 10 included radiographs from the following pattern: (1) P-30 with 1.0 mm defect,(2) P-30 with 1.6 mm defect, (3) Occlusin with 1.Omm defect, and (4) Occlusin with 1.6 mm defect. All films were individually mounted in black plastic mounts. Before interpreting the radiographs, the evaluators were told that each 1O-radiograph set included radiographs of teeth both with and without defects. They were then given diagrams on which to mark the location of any defects they observed. Thus, if no defect

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was observed, no mark was made. The evaluators were required not only to confirm whether a defect was present or not, but also to accurately locate the position of the defect. All radiographs were viewed on the same illuminator in a lighted room, without the aid of a magnifying glass. No time limit was imposed.” The film order was randomized for each evaluator. Each film was coded on the back to identify it to the investigator. RESULTS

The results of this study are summarized in Table I, and an example of an evaluator’s diagram is shown in Fig. 3. On average for all cases,the evaluators were over 90% accurate in their detection of the defects; however, individual evaluators were up to 30% inaccurate. The differing degreesof radiopacity and lesion sizesdid not affect the evaluators’ ability to correctly identify the defect within the parameters used for this study. It would appear that evaluator perception was more important than the other factors in this experimental study. DISCUSSION

Radiopacity is desirable in restorative materials because it allows radiographic differentiation between existing restorations and recurrent dental caries.* Secondary caries is apparently more common with posterior composite resins than it is with amalgam.4 Not only does it occur more frequently, but it also progressesat a substantially faster rate.4 A high degree of radiopacity has been deemeddesirable for radiographic interpretation$ however, our previous study lo showedthat, under certain circumstances, radiopacity of composite materials is unable to help reveal a small simulated carious defect (0.5 mm). The present study confirmed that there was no difference


detection of recurrent caries


between P-30 and Occlusin is radiographic images for detecting simulated dental caries defects associated with restorations. We express our appreciation to Dr. Farouk Mourshed and to Dr. Akira Yamamoto for his department’s support. REFERENCES I. Sewerin 1. Radiographic identification of simulated caries le-

sions in relation to fillings with Adaptic Radiopaque. Stand J Dent Res 1980;88:377-81. 2. Boksman L. Suzuki M. Jordan RE. Charles DH. A visible light-cured posterior composite resin; results of a 3-year clinical evaluation. J Am Dent Assoc 1986;112:627-3I. 3. Moffa JP, Jenkins WA, Hamilton JC. The longevity of composite resins for the restoration of posterior teeth [abstract]. J Dent Res 1984;63(special issue):199. 4. Leinfelder KF. Current development in posterior composite resins. Adv Dent Res 1988;2:115-21. 5. Stanford CM, Knoeppel R, Fan PL, Stanford JW, Schoenfeld CM. Radiopacity of light-cured posterior composite resins. J Am Dent Assoc 1987;115:722-4. 6. Lutz F, Phillips RW, Roulet JF, SetcosJC. In vivo and in vitro wearofpotentialposteriorcomposites. J Dent Res 1984;63:91420. 7. Omer OE, Wilson NHF, Watts DC. Radiopacity of posterior composite. J Dent 1986;14:178-9. 8. Tveit AB, Espelid I. Radiographic diagnosis of caries and marginal defects in connection with radiopaque composite fillings. Dent Mater 1986;2:159-62. 9. Tveit AB, Espelid I, Erickson RL. Radiographic diagnosis of caries adjacent to amalgam and composite restorations [abstract]. J Dent Res 1989;63(special issue):454. 10. Goshima T, Goshima Y. The optimum level of radiopacity in posterior composite resins. Dentomaxillofac Radio1 1989; 18:19-21. 11. Frommer HH. A comparative clinical study of group D and E dental film. ORAL SURG ORAL MED ORAL PATHOL 1987; 63:738-42. Reprint requests to:

Dr. Takeo Goshima Tokai Dental Clinic 3-4-14 Minami Shinagawa Shinagawa-ku, Tokyo 140 Japan

Radiographic detection of recurrent carious lesions associated with composite restorations.

The greatest potential problem associated with posterior composite restoration is secondary caries detection. It is essential that secondary caries is...
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