Marginal fidelity of crowns fabricated from six proprietary provisional materials

Marginal fidelity of crowns fabricated from six proprietary provisional materials Anthony H. L. Tjan, Dr Dent, DDS, PhD, a lacopo Castelnuovo, DDS, b and Goichi Shiotsu, DDS C

Loma Linda University School of Dentistry, Loma Linda, Calif., University of Rome "Tor Vergata," School of Dentistry, Rome, Italy, and University of Washington, School of Dentistry, Seattle, Wash. Statement of problem. The most important requirement for an interim crown is suitable marginal adaptation.

Purpose. This in vitro study compared vertical discrepancies of margins for complete crowns made with six provisional materials (Provipont, Protemp Garant, Unifast LC, Triad VLC, Splintline, and ~et).

Material and M e t h o d s . A direct technique was used to fabricate 60 provisional complete crowns on prepared molars with a polyvinyl siloxane impression and a vacuum-formed polypropylene sheet as matrices. A measuring microscope was used to measure vertical marginal discrepancies at ×100. Data were analyzed with Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests (~ = 0.05). Results. Significant differences were found between resinous materials tested (p = 0.0002) and multiple comparisons tests indicated no significant difference between Splintline and Protemp Garant; Provipont, Unifast LC, and Triad VLC; and Unifast LC, Triad, and Jet provisional materials. Conclusions. This study indicated that provisional crowns fabricated with Splintline and Protemp Garant interim restorative materials recorded the least marginal discrepancies. (] Prosthet Dent 1997;77:482-5.)

P r o v i s i o n a l restorations are used to protect and sedate the pulp of prepared abutments, promote periodontal healing and health, ~evaluate parallelism of abutments, replace missing teeth, prevent migration of abutments, and provide esthetics. Provisional restorations also assist in the development ofocclusal schemes and evaluation of phonetics, occlusal vertical dimension, and mastication. 2 In addition, they protect abutments from miroleakage and chemical injuries 3a and stabilize compromised teeth. S Provisional crowns are seated on the prepared abutments at a critical phase of treatment, because soft tissues have been injured inadvertently during tooth preparation. Therefore, the most important morphologic and Presented before the International Association of Dental Research, San Francisco, Calif., March 1996. aEmeritus Professor and Consultant in Biomaterials Research, Former Professor and Director of Biomaterials Research, Department of Restorative Dentistry, Loma Linda University. bResident, Graduate Prosthodontics, University of Washington; Associate, Department of Restorative Dentistry, University of Rome "Tot Vergata." CResident, Graduate Prosthodontics, Loma Linda University. 482

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physiologic requirements for an interim crown is suitable marginal adaptation. 2-s Shiny and s m o o t h surfaces w i t h o u t porosities, strength, retention during function, cleansibility, esthetics, comfort, desirable contours and adequate embrasures, harmonious occlusion, and color stability are all factors that have contributed to a well-integrated provisional restoration. 2 A hastily prepared, poorly adapted provisional restoration can result in plaque accumulation with subsequent periodontal problems that range from gingival inflammation with bleeding to gingival recession, especially when the margins of restorations are placed subgingivally.6,9 Provisional crowns with accurate marginal adaptation are compatible and promote gingival health.t° The purpose of this in vitro study was to compare the vertical marginal fidelity of provisional crowns made from six biomaterials by direct method. MATERIAL AND METHODS The materials tested, the manufacturer information, resin type, and batch number are listed in Table I. Provisional complete crowns were made by direct technique VOLUME 77 NUMBER 5

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Table I. Materials tested Product name

Provipont

ProtempGarant Unifast LC Triad VLC Splintline Jet

Manufacturer

Ivoclar Williams Ivoclar North America Inc. Amherst, N. Y. Espe Premier Sales Co. Norristown, Pa. GC America Inc. Chicago, Ill. Dentsply, York Division, York, Pa. Lang Dental Mfg. Co. Inc. Wheeling, IlL Lang Dental Mfg., Co. Inc.

Resin type

Batch number

Bis-GMA/UDMA

6541555

B[S-Acry[-Composite

9421

MMA

040842

UDMA

940425A

EMA Powder 2475PO2 MMA

Liquid 1122094 Liquid 1113094 Powder 055PO1

Fig. 1. Prepared Ivorene teeth mounted in dental stone block.

on prepared tTpodont teeth with an impression and a vacuum-formed template as matrices. Five artificial maxillary molar teeth (Ivorine teeth, Columbia Dentoform Corp., New York, N. Y.) were prepared for complete crown restorations with I mm shoulder finish lines 7 mm high with a taper o f approximately five degrees. The radicular portions were lubricated with petroleum jelly and mounted in a dental stone block (Fig. 1) to allow their removal for measurement of the marginal discrepancies o f the provisional crowns. V-grooves were cut on both ends o f the stone block to orient the matricies d u n g seating. Before teeth were prepared, an impression was m a d e with a high viscosity a d d i t i o n silicone (Permagum, ESPE-Premier Corp.) and a perforated acrylic resin custom tray with adhesive (Fig. 2). This impression served as a matrix for making the provisional crowns for all materials tested except for Triad VLC resin, which required a vacuum-formed polypropylene matrix (Fig. 3). Three autopolymerizing resins (Protemp Garant; Splintline; Jet) and three photopolymerizing resins (Provipont, Unifast LC, Triad VLC) were evaluated (Table I). Ten provisional crowns were made from each o f these materials according to the manufacturers with regard to mixing, manipulation, proportioning, time o f removal, and duration o f irradiation. Resin-filled matrices were adapted on lubricated master dies. The provisional crowns made with Triad VLC resin were photopolymerized for 10 seconds through the transparent matrix, then removed fi'om master dies and placed in a Triad VLC curing unit to complete the polymerization process. MAY 1997

Fig. 2. High viscosity addition silicone matrix.

All other matrix-material assemblies were secured firmly with rubber bands and immersed in a water bath set at 37 ° C. The provisional crowns were reseated once during the elastic phase of polymerization. After 2 minutes the crowns fabricated with Provipont and Unifast LC provisional restorative materials were removed from the matrix, seated on the master dies, and irradiated for 80 seconds. For the other resins, the excess material was periodically tested to indicate the appropriate time for provisional crown removal. Excess flash was trimmed away from the margins o f crowns with scissors. The crowns were reseated on tooth preparations and allowed to set completely in a water bath at 37 ° C for i 0 minutes. After curing was completed the gingival margins o f all provisional crowns were trimmed with a ×20 binocular microscope (Anchor Optical Co., H a d d o n Heights, N. J.). A spring-loaded holding device was used during measurement to secure provisional crowns on its preparation with a uniform load (Fig. 4). A centrally located hole at the base o f the tooth engaged the pointer rod that was incorporated in the device. The marginal discrepancy o f the provisional crown was measured with a 483

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TJAN, CASTELNUOVO, A N D SHIOTSU

PROVISIONAL CROWN

..2[-

t

T

DISCREPANCY*

T

Fig. 3. Vacuum-formed polypropylene matrix.

* Measured at four reference points Fig. 5. Determination of vertical marginal discrepancy performed by measuring discrepancy at four reference points. Table II. Means and SD of marginal discrepancy (mm) Product name

Resin

X

SD

(n = 10 per group) Splintline Protempt Garant Provipont Unifast LC Triad VLC Jet

EMA BIS-AcryI-Composite BIS-GMA/UDMA MMA UDMA MMA

0.18 0.22 0.29 0.36 0.39 0.40

0.123 0.136 0.065 0.103 0.152 0.094

Mean rank

13.2 [ 18.4 I 30.0 I 38.3 ] 40.5 42.5

II

Mean ranksconnectedby verticallinesare not significantlydifferent.

RESULTS

Fig. 4. Spring-loaded holding device.

microscope (Toolmakers' microscope, Mitutoyo, Japan) equipped with electronic digital micrometers calibrated to 0.001 mm at x l 0 0 original magnification. The marginal discrepancy was determined by measuring the space (marginal opening) between the margin of the crown and finish line oft_he tooth preparation (Fig. 5). For each crown and tooth preparation assembly, measurements were recorded at four reference vertical lines previously marked at the midpoint of the tooth preparation finish line for each face of the die. Measurements were recorded by one investigator to ensure consistency. The marginal discrepancy value was the arithmetic mean of these four measurements. I(,ruskal-Wallis one-way analysis of variance (ANOVA) and Mann-Whitney U-tests were used to analyze data because the homogeneity of variance assumption was not satisfied for both raw and log-transformed data. A significance level o f ~ = 0.05 was used for all statistical analyses. 484

Table II lists the mean and standard deviation values of marginal discrepancy for the six provisional materials tested (Fig. 6). The Kruskall-Wallis ANOVA test indicated significant differences between resinous materials (p = 0.0002). In particular, the Mann-Whitney U-test indicated no significant difference between Splintline and Protemp Garant resins (p = 0.236), among Provipont, Unifast LC, and Triad VLC resins (p = 0.070;p = 0.081; p = 0.3 ] ], respectively), and among Unifast LC, Triad VLC, and Jet resins (p = 0.311; p = 0.285; p = 0.454, respectively). Provisional crowns made with Splintline and Protemp Garant restorative materials recorded the least marginal discrepancies. DISCUSSION In this in vitro study, provisional restorations were fabricated by direct method and in particular by using the "on-off" technique described by Moulding et al., H for which interim crowns are removed once from the prepared t o o t h on initial polymerization and then reseated. That study demonstrated that provisional crowns made with the on-off technique were the least VOLUME 77 NUMBER5

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sensitive, and several interim crowns were remade during testing because of tearing during the elastic phase or surface irregularities such as marginal roughness and bubbles.

d.Marginai

lsqrep~ncy tmm) 0.45 0.4 0.35

iii!iiiii

0.3 0.25 0.2 0.15

0.1 Provipont

Protemp Unifast Garant LC

Triad

Splintline

Jet

VLC

Materials

Fig. 6. Graphic representation of means and standard deviations of marginal discrepancies. accurate compared with other techniques. 8,u The presence of undercuts in the prepared abutments and the possibility of injuring the pulp because of the temperature rise in the pulpal chamber during polymerization of resins suggested that provisional restorations should not remain on the prepared abutments during final curing. 12q4 Youdelis and Fancher1~suggested that provisional restorations could be repeatedly removed, teeth could be cooled with wateG and then the provisional restorations reseated. Conversely, removal of provisional crowns before sufficient curing can result in distortions. 4 However, it is possible that the six biomaterials in this study could record better marginal adaptation if the restorations were fabricated indirectly. It has been reported that provisional restorations were more accurate when an indirect m e t h o d was used compared to a direct method.4,6,11,16

In this study, measurements of marginal discrepancy were recorded within 3 hours after complete polymerization of provisional materials and with no relining procedures. Barghi et al.1 reported that relining of vented provisional restorations substantially improved marginal adaptation. Moreover, polymerization shrinkage of resins contributed in creating marginal discrepancy of provisional crowns) Koumjian and Holmes7discovered that marginal discrepancy increased after 1 week of storage in air, whereas water storage improved marginal adaptation for certain biomaterials. In this instance, storage in water appeared impractical because provisional crowns fabricated by direct method are intended for immediate use. Among the provisional restorative biomaterials tested, Protemp Garant resin clearly demonstrated ease of manipulation without, or with minimal, material waste. Provipont restorative material was extremely technique-

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SUMMARY This in vitro study compared the vertical marginal discrepancy of provisional crowns made with a direct method. Three autopolymcrizing resins (Splintline, Protemp Garant, Jet) and three photopolymerizing resins (Provipont, Unifast LC, Triad VLC) were tested. Interim crowns made with Splintline and Protemp Garant provisional restorative materials recorded the best marginal adaptation. REFERENCES 1. Barghi N, Simmons EW Jr. The marginal integrity of the temporary acrylic resin crown. J Prosthet Dent 1976;36:274-7. 2. Federick DR. The provisional fixed partial denture. I Prosthet Dent 1975;34:520-6. 3. Robinson FB, Hovijitra S. Marginal fit of direct temporary crowns, l Prosthet Dent 1982;47:390-2. 4. Tjan AH, Tjan AH, Grant BE. Marginal accuracy of temporary composite crowns. J Prosthet Dent 1987;58:414-21. 5. Kaiser DA. Accurate acrylic resin temporary restorations. J Prosthet Dent 1978;39:158-61. 6. Monday JJ, Blais D. Marginal adaptation of provisional acrylic resin crowns. J Prosthet Dent 1985;54:194-7. 7. Koumjian JH, Holmes lB. Marginal accuracy of provisional restorative materials. J Prosthet Dent 1990;63:639-42. 8. Moulding MB, Loney RW, Ritsco RG. Marginal accuracy of provisional restorations fabricated by different techniques, lot J Prosthodont 1994;7:468-72. 9. Waerhaug J. Temporary restorations: advantages and disadvantages. Dent Clin North Am 1980;24:305-16. 10. Donaldson D. Gingival recession associated with temporary crowns, j Periodonto[ 1973;44:691-6. 11. Moulding MB, Loney RW, Ritsco RG. Marginal accuracy of indirect provisional restorations fabricated on poly(vinyl siloxane) models, lot J Prosthodont 1994;7:554-8. 12. Grajower R, Shaharbani S, Kaufman E. Temperature rise in pulp chamber during fabrication of temporary self-curing resin crowns. ] Prosthet Dent 1979;41:535-40. 13. Tjan AH, Grant BE, Godfrey MF 111.Temperature rise in the pulp chamber during fabrication of provisional crowns. J Prosthet Dent 1989;62:622-6. 14. Martignooi M, Schonenberger A. Precision fixed prosthodontics: clinical and laboratory aspects. Chicago: Quintessence Pub Co; 1993:149. 15. Youdelis RA, Faucher R. Provisional restorations: an integrated approach to periodontics and restorative dentistry. Dent Clin North Am 1980;24:285303. 16. Crispin BJ, Watson JF, Caputo AA. The marginal accuracy of treatment restorations: a comparative analysis. J Prosthet Dent 1980;44:283-90. Reprint request to: DR. JAcoPo CASTELNUOVO VIA ARCHIMEDENO. 185

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