Resin-bonded fixed partial dentures. I. Proposed standardized criteria for evaluation

Resin-bonded fixed partial criteria for evaluation Morton Elaine Baltimore Md.

Wood, Romberg, College

DDS, PhD,” of Dental

MEd,a

Van

dentures.

P. Thompson,

and Grace V. Surgery, University

DDS,

I. Proposed

standardized

PhD,

Morrison, DDSd of Maryland at Baltimore,

Baltimore,

Since etched cast resin-bonded prostheses were introduced in 1980, many articles have been written about them. Most state that the reported clinical suiccess of these bonded restorations has been based primarily on the longevity of the bonding. For a comprehensive evaluation, however, it is important not only to examine the bonding but also to evaluate the periodontal response. The proposed standard method provides a consistent and comprehensive evaluation of resin-bonded prostheses that is applicable for researchers and clinicians alike.(J Prosthet Dent 1996;76:363-7.)

I

n 1980, etched, cast, resin-bonded fixed partial dentures (FPD) were incorporated as part of comprehensive patient treatment by students at the Dental School of the University of Maryland at Ba1timore.l Between 1980 and 1983,241 restorations were placed and primarily supervised by three faculty members. The main goals in selecting a resin-bonded FPD were to preserve tooth structure, maintain esthetics, and lower patient fees while providing restorations that had the potential for long-term service. Tooth preparations were minimal but still allowed the metal wings to wrap around the abutments and extend for maximal retention. The restorations were originally designed to be supragingival and have feathered gingival margins. Although the retainers were slightly overcontoured, they were thin and highly polished; it was anticipated that they would not contribute to an adverse periodontal response. Most of the literature on resin-bonded FPD, however, focuses on laboratory studies, is technique-oriented, or examines design-retention features, debond failures, and luting cements. 2-5 The primary clinical criterion is the length of time that restorations remained bonded. It has been demonstrated that resin-bonded FPD provide long-term service.‘j Now it is important to have a standardized approach that provides consistent, accurate, and convenient criteria that are useful to both researchers and clinicians. The following specific criteria make it possible to evaluate the long-term effects of resinbonded FPD according to the longevity of the bond and the periodontal response. The periodontal indexes and clinical response around abutments should be comparable to those of the control teeth. The presence of any restoration, however, is likely to cause an increase in

Supported “Associate bProfessor ‘Professor, %linical

OCTOBER

by NIH/NIDR grant No. ROl-DE09393. Professor, Department of Restorative Dentistry. Department of Restorative Dentistry. Department of Oral Health Care Delivery. Associate Professor, Department of Periodontics.

1996

plaque accumulation around the abutments.7s8 Loss of attachment is the most critical index of periodontal health and should not be substantially greater for abutments than for control teeth. If a population of patients with resin-bonded FPD are to participate in a longitudinal follow-up study, then calibrated baseline periodontal and prosthodontic indexes should be recorded.. If there are any statistically significant periodontal changes over time, these changes can be correlated with the prosthodontic indexes. This system establishes a relationship between the prosthesis and periodontal health. The purpose of this article is to describe a proposed standard method that allows consistent and comprehensive evaluation of resin-bonded prostheses. The method can be used by researchers and clinicians alike.

METHOD The proposed prosthodontic and periodontal evaluation criteria and indexes were developed for resin-bonded FPDs. The following describes the criteria in sequence of evaluation.

Periodontal

criteria

To determine the actual periodontal response around the abutments, it is important to evaluate appropriate control teeth. The primary choice of control should be the tooth contralateral to the abutment. When contralatera1 teeth are missing, restored with large lingual class V restorations or conventional FPD or are part of a restoration that crosses the midline, they should be excluded, and secondary control teeth should be substituted. Secondary control teeth should be selected according to the following criteria. First, teeth in the contralateral arch that are adjacent to the primary control teeth should be used if they meet the criteria listed for primary control teeth. Adjacent control teeth are selected because they are morphologically most similar to primary conTHE

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Fig. 1. Initial

view obtained at lo-year recall visit shows solid bridge of calculus limited to mandibular anterior FPD. Closer examination showed that soft tissues surrounding adjacent control teeth also were severely swollen, inflamed, and filled with calculus. To probe pocket depth and locate cementoenamel junction to measure recession, calculus must be removed.

trol teeth. Second, teeth with similar meet the criteria lected. To evaluate ing criteria were

Plaque

when adjacent teeth are not suitable, morphology on the opposing arch that for primary control teeth should be sethe periodontal response, the followused.

index

Control teeth are evaluated with a plaque index. The plaque index, as described by Silness and Loe,9 is used to evaluate the presence of plaque on the lingual areas of control teeth. A ranking of 0 through 3 is made at the mesiolingual, midlingual, and distolingual locations. When calculus is present, a plaque index of 3 is scored. A mean plaque index is then determined by averaging the three readings. The following rankings are recommended: 0, no plaque; 1, a film of plaque adhering to the tooth and free gingival margin seen when a periodontal probe is run across the tooth; 2, moderate accumulation of soft deposits on the tooth and free gingival margin seen with the naked eye; 3, abundance of soft matter on the tooth and free gingival margin. Abutments are evaluated by means of a modified plaque index. The modified plaque index is essentially the same as the plaque index, but it is modified slightly to evaluate the presence of plaque on the tooth, the free gingival margins, and the gingival margins of the casting. The modified plaque index was developed to evaluate resin-bonded FPD because abutments have the potential for increased levels of plaque retention. Plaque retention can increase if retainers are overcontoured, casting margins are in close approximation to the gingival crest, and small amounts of excess composite are present at the margins. Measurements are made for each abutment on the 364

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mesiolingual, midlingual, and distolingual sides. When calculus is present, a modified plaque index of 3 is scored. The mean modified plaque index is determined by averaging the three readings. The following rankings are recommended: 0, no plaque detectable on any margin; 1, a film of plaque adhering to the tooth and free gingival margin or gingival margin of the casting seen when a periodontal probe is run across the tooth; 2, moderate accumulation of soft deposits on the tooth and free gingival margin or gingival margin of the casting seen with the naked eye; 3, abundance of soft matter on the tooth and free gingival margin or gingival margin of the casting. If calculus deposits around either the abutment or control teeth prevent accurate measurement of pocket depth or recession, the deposits should be removed after an assessment of the gingival inflammation (Fig. 1).

Gingival

index

The gingival index, described by Lije and Silness,l”J1 is used to evaluate the degree of gingival inflammation on the lingual surface adjacent to the bonded retainers and the lingual surfaces of the control teeth. A ranking of 0 to 3 is made for each abutment on the mesiolingual, midlingual, and distolingual sides. The following rankings are recommended: 0, absence of inflammation; 1, mild inflammation (slight change in color and little change in texture); 2, moderate inflammation (moderate redness, edema, and hypertrophy); 3, severe inflammation (marked redness and hypertrophy). Bleeding with probing indicates a ranking of 2. Bleeding induced by an air syringe gives a ranking of 3. A mean gingival index is determined by averaging the three readings.

Probing

depth

The depth of the sulcus from the free crest of the gingival margin to the level of the attachment of the periodontal ligament is measured at six locations on abutments. The mesiobuccal, midbuccal, distobuccal, mesiolingual, midlingual, and distolingual locations are measured by use of a Williams periodontal probe inserted to the depth of the sulcus until resistance is met, as outlined by Ramfjord.12 Probing depths are recorded to the nearest 1 millimeter.

Recession A Williams periodontal probe is used to measure recession from the cementoenamel junction to the crest of the free gingival margin. The six locations on abutments listed for probing are measured. When the cementoenamel junction is apical to the crest, a negative (-) recording is made. When the gingival crest is apical to the cementoenamel junction, a positive (+) recording is made. All measurements are made to the nearest millimeter. VOLUME

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Fig. 2. Embrasure contour index. 0, A large gingival brush or periodontal aid easily passes embrasure or embrasure is visibly open. 2, Floss or small aid easily passes embrasure. 2, Space is limited but floss or periodontal probe passes embrasure. 3, Space is filled; floss or probing is not possible. Attachment

loss

Loss of attachment the readings obtained

PROSTHODONTIC Margin location

is measured from probing

by adding together and recession.

CRITERIA

The ideal cervical margin should be placed supragin.givally; however, tooth contours and demands for increased retention often dictate that margins be pIaced at the level of the gingival crest. The margin location of a potentially overcontoured retainer is critical in the evaluation of periodontal response. To determine the precise margin location, a Williams periodontal probe is placed along the lingual surface of the cast retainer and the distance from the cervical extent of the metal to the crest of the gingival tissue is measured and recorded to the nearest millimeter. If the gingival margins of the casting are subgingival, their distance is recorded as a negative measurement (-). Three sites on the lingual surface should be recordedmesiolingual, midlingual, and distolingual. Theses sit’es should remain consistent for all prosthodontic and periodontal rleadings to provide consistency for correlations between the restorations and the periodontal health.

Embrasure

contour

index

As compared with conventional fixed partial prosthodontics, interproximal tooth preparations for resin-bon’ded FPD are usually minimal and limited to enamel in the occlusal half. As a result, the gingival

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Fig. 3. Margin

contour index. 0, Ideal margin with smooth tooth-metal interface. 1, Thickened margin provides slight resistance to explorer. 2, Thickened margin provides moderate resistance to explorer. 3, Frank overhang provides complete resistance to explorer. embrasure space between the abutments and the pontic is often limited, causing difficulty in cleaning around this portion of the restoration. This embrasure space is particularly limited in the posterior regions. To determine whether the interproximal periodontal response is related to the contour of the embrasure between the abutment tooth and the casting pontic, embrasure contour indexes are recorded for the areas mesial or distal to the pontic. One evaluates embrasure contour by placing a periodontal probe between the abutment and adjacent pontic. The ratings are based on cleansibility and scored on a scale from 0 to 3, which depends on how much space is present (Fig. 2).

Margin

contour

index

Whether the gingival extent of the cast retainer is a feather type margin or a chamfer, when more distinct preparations are made, there should be a smooth transition between tooth structure and casting. However, retainers with less than ideal fit and contour are often found because of differences in tooth morphology, FPD design, quality of laboratory phases, operator skill, and need for bulk of metal to resist flexing. Because less than ideal gingival margins are commonly found, their contour should be evaluated to determine the quality of the tooth-metal interface. When moving an explorer from tooth structure to metal at 90 degrees to the surface, there should be a smooth junction rather than a bulk of material. Measurements are made at the gingival margins of the cast retainer on the mesiolingual, midlingual, and

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The criteria for adaptation are as follows: 1, all margins closed; 2, minor voids or defects; 3, debond. Voids found along the margins of the retainer give a score of 2 for the entire retainer. Debonds are scored as 3, and the entire restoration is listed as a debond failure even if one or more retainers are still well bonded.

Caries If caries is found, the tooth number, scription are recorded (Fig. 4).

location,

and de-

CALIBRATION

Fig. 4. A, Gross caries is evident on this mandibular premolar. B, Lingual view of same tooth reveals that premolar retainer has debonded and all surfaces in contact with retainer have become carious. Patient avoided dental treatment for almost 2 years after becoming aware of debond. distolingual aspects at the locations listed previously. The measurements are made with an explorer moved from tooth structure to the casting margin and graded from 0 to 3, which depends on how great a “catch” was detected (Fig. 3).

Adaptation All cast metal margins are checked circumferentially for the presence of voids or defects. A visual and manual inspection is performed with an explorer to determine how well the metal retainer was adapted to tooth structure. Originally it was believed that a disclosing dye, used for caries detection (Caries Detector, J. Murita USA, Inc., Tustin, CA), could be applied to the margins of the retainers to aid in detection of voids. The dye is applied for 10 seconds and rinsed, and the margins are inspected for retention or penetration of residual dye. It was theorized that dye retention would be an indicator of the initiation of debond; however, it was not effective. The only accurate and predictable method for detection of voids or debonds remains manual examination with the aid of a sharp explorer. 366

All evaluations are completed with calibrated examiners. It is essential that examiners be calibrated before the study begins in calculating the following periodontal indexes: (1) plaque indexes, (2) gingival index, and (3) loss of attachment. If a population is to be followed over time, recalibration every 6 months to 1 year is necessary. Calibration for the prosthodontic indexes also is important. During an initial calibration exercise, examiners must be able to agree on their rankings by consultation. Final determination of interexaminer calibration may be assessed through the use of the kappa statistic for modified plaque index, plaque index, gingival index, embrasure contour index, and adaptation.13 For measurements by means of probing, either Pearson’s r or the intraclass correlation coeffcient14 may be used depending on the total number of examiners.

CONCLUSION When the prosthodontic and periodontal indexes described herein are applied to resin-bonded FPD and selected control teeth, a comprehensive evaluation is possible. The clinical indexes are readily obtained in a brief recall visit so that the periodontal health and prosthodontic characteristics can be compared. REFERENCES 1. Livaditis GJ, Thompson VP. Etched castings: an improved retentive mechanism for resin-bonded retainers. J Prosthet Dent 1982;47:52-8. 2. Creugers NH, Snoek PA, Van’t Hof MA, I(iiyser AF. Clinical performance of resin bonded bridges: a &year prospective study. I. Design of the study and influence of experimental variables. J Oral Rehabil 1989;16:427-36. 3. Marine110 CP, Kershbaum T, Heinenberg B, et al. Experiences with resin-bonded bridges and splints: a retrospective study. J Oral Rehabil 1987;14:251-60. 4. Thayer KE, Williams VD, D&-Arnold AM, Bayer DB. Acid-etched, resin bonded cast metal prostheses: a retrospective study of 5- to 15- year old restorations. Int J Prosthodont 1993;6:264-9. 5. Wood M. Etched casting resin bonded retainers: an improved technique for periodontal splinting. Int J Periodont Restor Dent 982;2:825. 6. Boyer DB, Williams VD, Thayer KE, Denehy GE, Diaz-Arnold AM. Analysis of debond rates of resin-bonded prostheses. J Dent Res 1993;72:1244-8. 7. Creugers NH, Snoek PA, Vogels AL. Overcontouring in resin-bonded prostheses: plaque accumulation and gingival health. J Prosthet Dent 1988;59:17-21. 8. Freilich MA, Niekrash CE, Katz RV, Simonsen RJ. The effects of

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resin-bonded and conventional fixed partial dentures on the periodontium: restoration type evaluated. J Am Dent A,ssoc 1990;121:265-9. Silness J, L6e H. Periodontal disease in pregnancy. II. Correlation between oral hygiene and periodontal condition. Acta Odontol Stand 1964;22:112-35. L6e H, Silness J. Periodontal disease in pregnancy. I. Prevalence and severity. Acta Odontol Stand 1963;21:533-51. L6e II. The gingival index, the plaque index, and the retention index systems. J Periodontol 1967;38 Suppl:610-6. Ramfjord SP. The periodontal disease index (PDI). J Periodontol 1967;38:602-10. Landis JR, Kock GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159-74. Cohen ME, Cecil JC. Intraclass correlation and the application of analysis of variance to dental data. J Dent Res 1983;62:322-6.

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CONTRIBUTING

JOURNAL

OF PROSTHETIC

DENTISTRY

AUTHOR

Jon B. Suzuki,

DDS, PhD, Professor

University of Pittsburgh burgh, Pa.

School of Dental

and Dean, Medicine, Pitts-

Copyright 0 1996 by The Editorial Council of The Journal Prosthetic Dentistry. 0022-3913/96/$5.00 + 0. 10/l/75276

of

to:

DR. MORTON WOOD DEPARTMENT OF RESTORATIVE DENTISTRY 666 WEST BALTIMORE ST. BALTIMORE, MD 21201

Microleakage

and thermal

properties

of hybrid

ionomer

restoratives.

Puckett

AD, Fitchie JG, Bennett B, Hembree JH. Quintessence Int f995;26:577-81. Purpose. Since their introduction in 1972 glass-ionomer materials have undergone major clinical improvements. Today glass-ionomers are used as luting cements, non-stress-bearing area restorative materials, liners/bases, and core build-up materials. Studies on glass-ionomer clinical performance have shown a reduction in marginal microleakage because they chemically bond to tooth structure and tlheir coefficient of thermal expansion is similar to natural tooth structure. This makes them useful in the restoration of the class V erosive or carious lesions or where esthetics is important. This study determined the in vitro microleakage and thermal properties Iof two new hybrid glass-ionomer materials, Variglass VLC (LD CaulMDentsply Int) and Fuji II LC (GC America). The results obtained were compared with those obtained from a conventional glass-ionomer (Ketac-Fil Applicap, ESPE Premier). Material and Methods. Thirty extracted bovine incisors were used!. Class V preparations (2 mm axially, 3 mm mesiodistally, 2 mm incisocervically) wer’e made on the facial surface of each tooth. The teeth were divided into groups of 10 and restored with either Ketac-Fil (group l), Variglass (group 2), or Fuji II (group 3) material. The teeth were aged and then placed in calcium 45labeled isotope for 2 hours and sectioned, and x-ray examination was performed to produce autoradiographs. In addition, to evaluate thermal expansion, five standard cylindric specimens of each material was made according to the manufacturer’s directions. These were tested with a thermal mechanical analyzer (Mettler Instruments) to determine each material’s thermal expansion. Data were collected and analyzed; materials were compared by use of the Mann-Whitney U test. Results. The conventional glass-ionomer Ketac-Fil Applicap material exhibited significantly less microleakage and thermal expansion than either of the two new hybrid materials tested. The two newly introduced hybrid materials appeared to exhibit different thermal behavior. Fuji II material exhibited many of the characteristics of a conventional glass-ionomer, whereas the Variglass acted like a glass-filled composite. 12 References.RP Renner

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1996

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