Shiono et al.

Int Chin J Dent 2005; 5: 17-21.

Clinical evaluation of jacket crowns made of the Estenia indirectcomposite
Hideaki Shiono, DDS, PhD,a,b Hiroyasu Koizumi, DDS, PhD,b,c Mika Nemoto, DDS,PhD,b,c Yumi Ishikawa, DDS,b Hideo Matsumura, DDS, PhD,b,c and Naomi Tanoue,DDS, PhDdab

Private Practice, Saitama, Department of Crown and Bridge Prosthodontics, Nihon University School
cof Dentistry, Tokyo, Division of Advanced Dental Treatment, Dental Research Center, NihondUniversity School of Dentistry, Tokyo, and Department of Specialized Dentistry, Nagasaki University
Hospital of Medicine and Dentistry, Nagasaki, Japan
Purpose: The purpose of the present study was to evaluate the clinical performance of jacket crowns made of ahighly loaded indirect composite material.
Materials and Methods: A total of 25 jacket crowns made of the Estenia composite were seated withresin-based luting agent, and thereafter clinically evaluated using modified USPHS criteria. Color match,marginal integrity, surface texture, wear of both restoration and antagonist, recurrent dental caries, fracture ordetachment, and gingivitis around the abutments were examined. The observation period varied from 16 to 83
months with an average of 38.9 months.
Results: All crowns were judged as Alfa for all categories at baseline. After an average observation period of
38.9 months, the following number of cases were judged as Bravo; one for color match, nine for surface texture,
one for wear, five for wear of the silver-palladium alloy antagonists, and two for gingival inflammation. Wearof enamel antagonists, however, was not remarkable. Deterioration of marginal integrity, recurrent dental caries,and fracture of crown were not observed in any patients.
Conclusion: It can be concluded that the Estenia composite is clinically applicable for use as jacket crowns.
(Int Chin J Dent 2005; 5: 17-21.)
Clinical Significance: Clinical evaluation demonstrated that jacket crowns made of the Estenia composite canfunction satisfactorily for more than three years.
Key Words: clinical evaluation, composite, jacket crown.

Introduction
The use of composite materials for restoration and fixed partial dentures (FPDs) has increased substantially,
probably due to improvement in material properties. The Estenia material (Kuraray Medical Inc., Tokyo, Japan)
is one of the most highly loaded composites applicable for indirect tooth-colored restorations.

In vitro

evaluation demonstrated that the Estenia composite is superior in color stability,1 wear resistance,2,3 and flexuralstrength,4 to other composites. Indication of the Estenia composite was therefore extended from single indirect
restorations5,6 to cast veneered FPDs,7 super-structure of implant-supported prostheses,8 and fiber-reinforced
FPDs.9Although the property test results and clinical procedure of Estenia restorations have been extensively
reported, limited information is available about clinical results of restorations made from the Estenia composite.
This study reports on the clinical performance of jacket crowns made from the Estenia composite, after an
average observation period of 38.9 months.

Materials and Methods
The Estenia composite was selected for clinical evaluation.

The material consists of 8% hydrophobic

multifunctional methacrylates including urethane tetramethacrylate (UTMA), 16% submicron filler (0.02 µm),
and 76% glass filler (1.5-2.0 µm). The total filler loading is 92%.

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Int Chin J Dent 2005; 5: 17-21.

A total of 21 adult patients (20 females and one male), in whom full coverage tooth-colored restorations wereplanned, were successively included. Twenty-five teeth (one maxillary incisor, two maxillary canines, 14
maxillary premolars, and eight mandibular premolars) were restored in the current study. The abutment wasprepared according to the conventional design for a jacket crown with approximately 1.2 mm rounded shoulder
preparation and 1.5-2.0 mm occlusal plane reduction.
Table 1.

Modified USPHS criteria for direct clinical evaluations.

Category/Rating

10-12

Characteristics

Color match
AThe restoration appears to match the shade and translucency of adjacent tooth tissues.
B
The restoration does not match the shade and translucency of adjacent tooth tissues, but the mismatch is within thenormal range of tooth shades.
CThe restoration does not match the shade and translucency of adjacent tooth, and the mismatch is outside
the normal range of tooth shades and translucency.
Marginal integrityA
The explorer does not catch when drawn across the surface of the restoration toward the tooth, or, if the explorer
does catch, there is no visible crevice along the periphery of the restoration.
B
The explorer catches and there is visible evidence of a crevice, into which the explorer penetrates, indicating thatthe edge of the restoration does not adapt closely to the tooth structure.
C
The explorer penetrates a crevice defect.
Surface texture
A
Surface texture similar to polished enamel as determined by means of a sharp explorer.
B
Surface texture gritty similar to a surface subject to a white stone or similar to a composite containing
supramicron sizes particles.
CSurface pitting is sufficiently coarse to inhibit the continuous movement of an explorer across the surface.
WearA
B
C

The restoration is a continuation of existing anatomic form or is slightly flattened.
A surface concavity is evident.
There is a loss of restorative substance such that a surface concavity is evident. Replacement is required.

Wear of antagonist
AThe antagonist is a continuation of existing anatomic form or is slightly flattened.
BA surface concavity is evident.
C
There is a loss of antagonist substance such that a surface concavity is evident. Replacement or restorative
treatment is required.
Recurrent dental caries
A
The restoration is a continuation of existing anatomic form adjacent to the restoration.
C
There is visual evidence of dark deep discoloration adjacent to the restoration.
Fracture/Detachment
ANo bulk fracture/detachment is present.
C
Bulk fracture/detachment is evident.
GingivaA
No clinical inflammation is present.
B
Clinical inflammation is present.
A, Alfa; B, Bravo; C, Charlie.

An impression was made with a silicone elastomeric material, poured with lab stone and die stone, and aworking cast was prepared. A composite jacket crown was fabricated with the Estenia composite according to
the manufacturer’s specifications. An opaque composite was used for specific cases to hide the metallic color of
the abutment dowel core. On the patient’s next visit, the jacket crown was tried-in, occlusion and articulation
were adjusted, and the crown was seated with one of the resin-based luting agents. Clearfil DC Cement, Panavia18Shiono et al.

Int Chin J Dent 2005; 5: 17-21.

F dual activated composites (Kuraray Medical Inc.) as well as other resin-based luting materials were employedfor luting. The patients entered a check-up program and oral examination was continued once or twice a year.
The jacket crowns were evaluated immediately after seating (baseline), after one year, and again after two or
three years. On the basis of the modified United States Public Health Service (USPHS) criteria, the following
characteristics of the crowns were evaluated: color match, marginal integrity, surface texture, wear of bothrestoration and antagonist, recurrent dental caries, fracture or detachment, and gingivitis around the abutments.
The modified USPHS guidelines used in the current study are shown in Table 1.10-12
The worn surface of an antagonist restoration was observed with a scanning electron microscope (SEM)
operated at 15 kV. The current study was performed in compliance with permission for use of human subjects
from the Medical Ethics Committee, Nihon University School of Dentistry.

Results
Table 2 shows the clinical evaluation of the jacket crowns at baseline and after an average observation periodof three years and 2.9 months. All crowns were judged as Alfa for all categories at the baseline evaluation. Thenumbers of crowns judged as Bravo rating at the recall visit were nine for surface texture, five for wear ofantagonist, two for gingivitis, one for color match, and one for wear of jacket crown. The remaining crowns
were judged as Alfa for all categories. In the current study, no crowns were judged as Charlie for any of thecategories.
Table 2.

Clinical evaluation of jacket crowns made of the Estenia composite.

Category
RatingColor match
Marginal integrity
Surface texture
Wear of jacket crown
Wear of antagonist
Recurrent caries
Fracture/Detachment
Gingiva

A2525252525252525Baseline
B00000After ave. 38.9 months
ABCC
000000024
24
16242025
25*
23010
91
50000000

Note

Ag-Pd alloy antagonist
Ag-Pd alloy antagonists

2A, Alfa; B, Bravo; C, Charlie. N=25. *Two dowel cores detached, but were re-seated.

12Figs. 1, 2. Buccal view of a jacket crown made of the Estenia composite during cementation (1) andthree years after insertion (2). The patient was satisfied with the clinical course of thetreatment.

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Int Chin J Dent 2005; 5: 17-21.

Fig. 3. Slightly worn antagonist opposed to
the Estenia jacket crown.

Fig. 4. An interface between the worn surface(lower right) and the intact surface.

Figs. 1 and 2 show a typical buccal view of a jacket crown during cementation and three years after insertion.
Degradation was not detected for majority of the crowns when they were in contact with saliva. Figs. 3 and 4
show scanning electron micrographs of a worn antagonist lingual cusp detected after two years and two months
from the baseline evaluation. The antagonist crown was made of a silver-palladium-copper-gold (Ag-Pd) alloy.
It was notable that a total of five antagonists showed moderate wear judged as Bravo, all of which were castrestorations made of silver-palladium-copper-gold alloy.

Discussion
The clinical evaluation of jacket crowns made of the Estenia composite demonstrated favorable results. Ofthe 25 jacket crowns, nine exhibited slight frosty appearance when the crown surface was air-dried. Surface
roughness of the crowns, however, was not distinct when the surface was in contact with saliva.

Thisphenomenon is clinically acceptable because it is desirable for individual dentition that the wear rate of natural
teeth and restorative materials is equivalent. The slightly roughened surface detected in the current cases could
be polished with a rotary silicone instrument containing file diamond particles (Compomaster, Shofu Inc., Kyoto,Japan).
Clinical evaluation also revealed that wear of antagonists was evident when they were restored with castrestorations made of Ag-Pd alloy. This is probably due to insufficient wear resistance and hardness of Ag-Pd
alloy when opposed to the Estenia composite, especially in the area of centric holding cusp.
As shown in the clinical results, jacket crowns made of the Estenia composite demonstrated clinical successfor all cases even after three years or more. On the basis of the current evaluation, it can be concluded that theEstenia composite is a clinically reliable material for use in anterior and premolar jacket crowns.
Acknowledgment
This work was supported in part by a Grant from Dental Research Center, Nihon University School of Dentistry, 2004.

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Reprint request to:
Dr. Hiroyasu Koizumi
Department of Crown and Bridge Prosthodontics, Nihon University School of Dentistry
1-8-13, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8310, Japan
Fax: +81-3-3219-8351 E-mail: koizumi@dent.nihon-u.ac.jp
Received January 4, 2005. Revised January 22, 2005. Accepted January 26, 2005.
Copyright ©2005 by the Editorial Council of the International Chinese Journal of Dentistry.

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