Shiono et al.

Int Chin J Dent 2009; 9: 39-43.

Seven-year clinical evaluation of indirect restorations made of theEstenia composite
Hideaki Shiono, DDS, PhD,a Hiroyasu Koizumi, DDS, PhD,a,b Masakazu Hirata, DDS,aMichiya Ayano, DDS,a Daisuke Nakayama, DDS,a and Hideo Matsumura, DDS, PhD,a,bab

Department of Fixed Prosthodontics, and Division of Advanced Dental Treatment, Dental ResearchCenter, Nihon University School of Dentistry, Tokyo, Japan
Purpose: The aim of this study was to evaluate the clinical performance of tooth-colored crown restorations
made of a highly loaded indirect composite material.
Materials and Methods: A total of 17 restorations made of the Estenia indirect composite were clinicallyevaluated on the basis of the modified USPHS criteria. Color match, marginal integrity, surface texture, wear ofrestoration as well as antagonist, recurrent dental caries, fracture/detachment, and gingivitis around theabutments were examined. The observation period varied from 50 to 125 months with an average of 87.5
months.
Results: All restorations were judged as Alfa for all categories at baseline. After an average observation periodof 87.5 months, the following cases were judged as Bravo; eight for surface texture, one for wear, five for wearof the metallic antagonists, and one for gingival inflammation. Fracture of the restoration was detected in one
case. Problems associated with color match, marginal integrity, wear of enamel antagonists, and recurrent dental
caries were not observed in any patients.
Conclusion: Within the limitation of current evaluation, it can be concluded that the expected service period of
the indirect restorations made of the Estenia composite is five years or more. (Int Chin J Dent 2009; 9: 39-43.)
Key Words: clinical evaluation, composite, indirect restoration.

Introduction
Over the last decade, the application of composite materials for indirect restorations has increasedsubstantially.

This trend is probably due to improvement in both mechanical and handling properties ofmaterials. The Estenia material (Kuraray Medical Inc., Tokyo, Japan) is one of such composites applicable forindirect tooth-colored restorations. Laboratory evaluation demonstrated that the Estenia composite is superior incolor stability,1 wear resistance,2-5 and strengths,6,7 to other composites. The Estenia material is therefore
currently used for single restorations,8-10 fixed partial dentures (FPDs),6,11-13 as well as the super-structure of
implant-supported prostheses.14,15
Although in vitro assessment of the Estenia material has been reported extensively, only limited information isavailable concerning the clinical performance of restorations made of the Estenia composite.9,10 This report
evaluated clinically 17 single indirect restorations fabricated with the Estenia composite on the basis of modified
United States Public Health Service (USPHS) criteria, after an average observation period of seven years and3.5 months.

Materials and Methods
The Estenia composite material, which consists of 8% hydrophobic multifunctional methacrylates andurethane tetramethacrylate (UTMA), 16% submicron filler (0.02 µm), and 76% glass filler (1.5-2.0 µm), wasused in fabrication of restorations.
Sixteen adult female patients participated in the evaluation. Seventeen teeth (one maxillary incisor, one
maxillary canine, 11 maxillary premolars, and four mandibular premolars) were restored. The abutment wasprepared according to a typical design for a tooth-colored restoration with approximately 1.2 mm roundedshoulder preparation and 1.5-2.0 mm occlusal surface or incisal edge reduction.

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Table 1.

Int Chin J Dent 2009; 9: 39-43.

Modified USPHS criteria for direct clinical evaluations.

Category/Rating

10,16-18

Characteristics

Color matchA
The 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 teeth, and the mismatch is outside
the normal range of tooth shades and translucency.
Marginal integrity
AThe 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.
BThe 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.
CThe explorer penetrates a crevice defect.
Surface texture
ASurface texture is similar to polished enamel as determined by means of a sharp explorer.
BSurface texture is 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 antagonistA
The antagonist is a continuation of existing anatomic form or is slightly flattened.
B
A 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 elastomeric material, and a working cast was prepared.

A composite

restoration was fabricated with the Estenia system according to the manufacturer’s specifications.

Therestoration was tried-in and seated with the Panavia F dual activated luting composite (Kuraray Medical Inc.) orwith other resin-based luting agents. The patients entered a regular check-up program with oral examination
once or twice per year.
The restorations were evaluated immediately after seating (baseline) and periodically evaluated up to 10 years.
On the basis of the modified USPHS criteria, the following characteristics of the restorations were evaluated;color match, marginal integrity, surface texture, wear of both restoration and antagonist, recurrent dental caries,
fracture or detachment, and gingivitis around the abutments. The modified USPHS criteria used in the current
study are shown in Table 1.10,16-18 This study was performed in compliance with permission for use of humansubjects from the Medical Ethics Committee, Nihon University School of Dentistry (No. 2007-3).

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Int Chin J Dent 2009; 9: 39-43.

Results
Table 2 summarizes the results of clinical evaluation of the restorations at baseline and after an averageobservation period of seven years and 3.5 months. All restorations were judged as Alfa for all categories at thebaseline evaluation. The numbers of restorations judged as Bravo rating at the recall visit were eight for surface
texture, one for wear of restoration, five for wear of antagonist, and one for gingivitis. It was notable that a totalof five antagonists showed moderate wear judged as Bravo, all of which were cast restorations made of gold or
silver-palladium-copper-gold alloy. Fracture of the restoration occurred in one case, in which a hair-line crack
generated at the lingual surface of a maxillary second premolar. The remaining restorations were judged as Alfa
for all categories.
Table 2.

Clinical evaluation of crown restorations made of the Estenia composite material.

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

ABaseline
B

171717171717171700000

After ave. of 87.5 months
ABCC0000000

17
17
916
1217
16
16000
81
50000001

Note

Incisal edge
Five metallic antagonists

1A, Alfa; B, Bravo; C, Charlie. N=17.

Fig. 1. Buccal view of the abutment.

Fig. 2. A restoration made of the Estenia composite.

Figs. 3 and 4. Buccal (left) and occlusal (right) views of the restoration seated after eight years and 10 months.

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Int Chin J Dent 2009; 9: 39-43.

Figs. 1 through 4 show a typical restoration made of the Estenia composite.

This case did not show

discoloration, wear, and fracture of the restoration after service period of eight years and 10 months. Recurrent
dental caries was not detected, and condition of periodontal tissue appeared to be satisfactory. The patient wassatisfied with the clinical course of the treatment.

Discussion
Previous studies9,10 have demonstrated the effectiveness of the Estenia composite as a tooth-coloredrestorative material. This study evaluated longevity of the Estenia restorations for up to a maximum of 10 years
and five months on the basis of the modified USPHS criteria. The results after an average observation period of87.5 months were substantially similar to the results of 38.9-month evaluation.10 Specifically, eight of the 17
restorations exhibited a frosty appearance after their surface was air-dried. Roughening of the restorations,however, was not distinct when the surface was in contact with saliva. This phenomenon is not ideal but
clinically acceptable since it is desirable for individual dentition that the wear rate of natural teeth and restorative
materials is equivalent. The roughened surface could be polished with a rotary silicone instrument with file
diamond particles (Compomaster, Shofu Inc., Kyoto, Japan).
Wear is closely related to surface texture of both tooth and restorative materials. Ogino et al.5 evaluated wear
characteristics of the Estenia composite and gold alloy using a gold alloy antagonist. The results indicated thatthe Estenia composite was more wear resistant than gold alloy. The results agree with the clinical results of thecurrent and previous10 studies.

Table 2 shows that five worn antagonists were made of either gold or

silver-palladium-copper-gold alloy. The remaining antagonists that did not show remarkable wear were enamelof natural dentition. This may be due to insufficient wear resistance and hardness of alloys when opposed to theEstenia composite, especially in the area of the centric holding cusp.
As revealed in this evaluation, restorations made of the Estenia composite demonstrated clinical success in themajority of cases after seven years or more. On the basis of the current clinical results, it can be concluded that
the Estenia composite is a clinically reliable material for use in anterior and premolar tooth-colored restorations.
Acknowledgment
This work was supported in part by Sato Fund (2009) and Grant from Dental Research Center B (2008), Nihon University
School of Dentistry, and Special Research Grants for the Development of Distinctive Education from the Promotion andMutual Aid Corporation for Private School of Japan (2009).

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Correspondence to:Dr. Hiroyasu Koizumi
Department of Fixed 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
Accepted August 28, 2009.

Copyright ©2009 by the International Chinese Journal of Dentistry.

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