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9Q U I N T E S S E N C E I N T E R N AT I O N A L

VOLUME 45 NUMBER 1 JANUARY 2014

Clinical evaluation of anterior all-ceramic resin-bonded xed dental prosthesesAristidis A. Galiatsatos, DDS, Dr Dent1/Dimitra Bergou, DDS2

Objectives: All-ceramic resin-bonded xed dental prostheses (RBFDPs) were introduced as a conservative treatment many years ago. The purpose of this study was to evaluate for 8 years the clinical survival of RBFDPs made with a conventional two-retainer design. Method and Materials: A total of 54 an ter-ior RBFDPs were made from the glass-inltrated alumina ceramic In-Ceram. The restorations were placed in 49 patients, aged 18 to 60 years, by a single operator using the same clin-ical procedure. The restorations were examined for debonding, fracture rate, caries, and patient acceptance. All restorations

were examined clinically at 1, 2, 4, 6, and 8 years after place-ment. Results: At 8 years, the success rate was 85.18%. Patient acceptance was very encouraging and dental caries were not detected with any abutment. Two restorations debonded dur-ing the evaluation period and fracture of porcelain occurred in six restorations (two total fractures and four partial fractures). Conclusion: All-ceramic RBFDPs made from high-strength oxide ceramics oer an eective conservative treatment for replacing anterior teeth. (Quintessence Int 2014;45:914; doi: 10.3290/j.qi.a30766)

Key words: clinical performance, esthetics, fracture, In-Ceram system, resin-bonded FDP

RESTORATIVE DENTISTRY

Aristidis A. Galiatsatos

torations may present disadvantages with regard to

esthetics and biocompatibility.14-16 The esthetically

unsatisfactory grayish shine through of metal is a

common problem in the anterior region. The biocom-

patibility of certain nonprecious alloys has been ques-

tioned because of their corrosive, allergenic, and even

mutagenic potentials.14-18

To overcome these problems, all-ceramic RBFDPs

were introduced.19-21 It has been shown by several

authors that the aluminum oxide ceramic In-Ceram

(Vita Zahnfabrik) has much better physical properties

than other ceramic or glass materials.22-27 For this rea-

son, RBFDPs have been suggested as an alternative to

traditional resin-bonded restorations, which use a

metal framework.25 The recommended design of In-

Ceram prostheses is similar to the design of the con-

ventional metal-ceramic resin-bonded restorations.25

Several studies on all-ceramic RBFDPs have been

Conventional resin-bonded xed dental prostheses

(RBFDPs) with metal framework have been used in den-

tal practice for many years as alternatives to conven-

tional FDPs when abutments are intact or exhibit only

minimal caries lesions.1-5 The longevity of the prosthe-

ses has been improved since the initial use as a result of

preparation of the abutment teeth and a variety of new

methods to increase mechanical and chemical resin-to-

metal retention.2,6-9

The most common type of failure with RBFDPs is the

debonding of the cast metal framework from the luting

cement, but debondings of the luting cement from the

enamel surface have also been reported.10-13 These res-

1 Assistant Professor, Department of Dental Technology, Division of Fixed Pros-thodontics, Technological Educational Institution of Athens, Athens, Greece.

2 Private practice, Athens, Greece.

Correspondence: Dr Aristidis A. Galiatsatos, 60 Str. Rogakou Str., 15125 Athens, Greece. mail: [email protected]

10

Q U I N T E S S E N C E I N T E R N AT I O N A L

Galiatsatos / Bergou


reported and the observation periods and success rates

in these reports vary considerably.

The purpose of this study was to add to the knowl-

edge of all-ceramic RBFDPs by evaluating the long-

term clinical survival of such restorations.

METHOD AND MATERIALS

The study population consisted of 49 patients. There

were 28 women and 21 men, ranging in age from 18 to

60 years (Table 1). Patient selection was accomplished

according to preestablished criteria. Abutments were

intact and caries-free, or exhibiting only minimal lesions

that did not interfere with bonding, and tooth alignment

was acceptable. Patients who exhibited bruxism, deep

bite situation, severe inammation, poor oral hygiene, or

a high caries rate were ineligible for this study. Only

patients with one missing mandibular or maxillary an ter-

ior tooth (central or lateral incisor) were selected. Five of

them had both one missing maxillary and one missing

mandibular anterior tooth. None of the selected patients

dropped out or were dismissed. In the majority of the

cases, an implant-supported prosthesis was not advis-

able as available bone volume was minimal, or the adja-

cent root was in close proximity.28 Also, many patients

declined the several surgical procedures required.

The selected patients were provided with a total of

54 anterior RBFDPs with a conventional two-retainer

design in a private practice. The glass-inltrated alumi-

num ceramic In-Ceram technique was selected to fabri-

cate the above restorations. The distribution of the

restorations is presented in Table 2. The reasons for the

loss of teeth in this study were congenitally missing

teeth, trauma, dental caries, endodontic complications,

and periodontal disease (Fig 1).

All procedures were performed by a single investi-

gator, and all materials were mixed and used according

to the recommendations of the manufacturers. Shades

were matched with the Vita-Lumin Vacuum shade

guide (Vita Zahnfabrik).

All abutments were prepared according to common

principles for these kinds of restorations.25,29-31 The lin-

gual surfaces were reduced by approximately 0.5 mm

to provide space for a sucient thickness of ceramic

material. The margins of the preparations were approx-

imately 1 mm from the gingival margin and 1 to 1.5 mm

from the incisal edge with a supragingival chamfer n-

ish line. The proximal surfaces of abutments adjacent to

the edentulous space were prepared to reduce convex-

ity and provide an increased tooth surface available for

bonding. An additional shallow box preparation was

made in each abutment proximally to the pontic side

(dimensions approximately 2 2 0.5 mm).32,33 Proxi-

mal contact areas were not invaded.

Full-arch impressions were made with a single

impression/double mixing technique and polyether ma-

Table 2 Distribution of the restorations

Arch location No. of RBFDPsReplaced central incisors

Replaced lateral incisors

Maxilla 30 20 10

Mandible 24 15 9

Total 54 35 19

Table 1 Age and gender of patients

Age (years) Men Women Total

1830 10 12 22

3140 8 8 16

4150 2 4 6

5160 1 4 5

Total 21 28 49

Fig 1 Preoperative view of a patient with congenitally missing lateral incisor.

11




terial (Permadyne, 3M Espe). Provisional restorations

were made by placing composite resin (Tetric Ceram,

Ivoclar Vivadent) directly on prepared unetched surfaces,

nished, and polished. At the second visit, the provi-

sional restorations were easily removed with a scaler.

The In-Ceram restorations were constructed by the

same technician in accordance with the manufacturers

recommendations within 1 week after the nal impres-

sions were made (Fig 2).

The inner surfaces of the restorations were air

abraded with aluminum oxide particles (Korax 250,

Bego) and coated with silane (Monobond S, Ivoclar

Vivadent). After isolation of the teeth, the prepared

surfaces of the abutment teeth were thoroughly

cleaned with pumice slurry and etched with 37% phos-

phoric acid gel (Ultra-Etch, Ultradent) for 60 seconds,

rinsed with water spray, and dried with air pressure.

The dentin adhesive system Syntac Classic (Ivoclar Viva-

dent) was then applied.

The ceramic restorations were cemented with dual

polymerizing composite resin cement (Variolink II, Ivoclar

Vivadent). After cementation, the occlusion was carefully

evaluated and necessary corrections were performed.

Finally, the inserted restorations were nished with dia-

monds burs and polishing disks and strips (Sof-Lex, 3M

Espe). Intraoral color photographs were taken (Fig 3). All

patients received oral hygiene instructions with special

emphasis on the proximal and lingual surfaces.

The patients were examined clinically at 1, 2, 4, 6,

and 8 years after placement of the restorations. Such

periodic tests were conducted by the authors with a

mirror, a sharp probe, and intraoral photographs.

To assess reliability, 10% of the restorations were

reexamined after 1 month, in order to conrm the nd-

ings of the rst examination.

The following information was recorded during the

examination:

Debonding. Each retainer was checked for debond-

ing through nger pressure and a sharp probe. The

units were classied as debonding when it was pos-

sible to force the sharp tip between the retainer and

the abutment, and when pushing the abutment

teeth in the opposite direction of the restoration

there was a visible gap between the retainer wing

and the abutment.

Fracture. The fractures were divided into total and

partial fractures. The loss of the restoration due to

fracture of the ceramic was dened as a total frac-

ture. A fractured restoration which remained in clin-

ical service as a cantilevered FDP was considered a

partial fracture.

Caries. All abutment teeth were examined to detect

presence of dental caries by clinical examinations

and by intraoral radiographs.

Patient acceptance. The patients were asked about

the esthetic appearance of the restorations, their

chewing ability, problems with cleaning, and symp-

toms of masticatory parafunction or dysfunction. A

questionnaire presented an opportunity for giving

alternative answers and personal remarks.

Fig 2 Palatal view of the In-Ceram framework on the master cast.

Fig 3 Intraoral view of completed treatment immediately after insertion.

12




RESULTS

The results after 8 years of service are shown in Table 3.

The reliability test showed no disagreement. Dental

caries was not detected with any abutment during the

observation time.

On the 49 patients reexamined, 48 were satised

with the function and the esthetic appearance of their

restorations. The unsatised patient had a broad maxil-

lary anterior edentulous space and the pontic created

an asymmetrical appearance. All patients stated that

the prosthesis did not cause any subjective symptoms

such as headache, and their chewing ability was very

good and satisfactory. Five patients avoided using their

prostheses during chewing or biting on hard food,

because they had previous fractures of porcelain-fused-

to-metal crowns in the posterior teeth and, therefore,

feared a new failure.

Two restorations debonded during the evaluation

period. Both of them were in the mandibular arch. In

the rst case, 3 years after the insertion of the restor-

ation, the patient complained about mobility of the

pontic replacing the mandibular right central incisor.

Clinical examination revealed the wing on the man-

dibular right lateral incisor to be loose. In an attempt to

create space to recement, the connector on the man-

dibular left central incisor was fractured. In the second

case, which was similar, the pontic of the restoration

was replacing the mandibular left lateral incisor and the

wing debonded after a period of 3.5 years of clinical

use. The fractured RBFDPs were removed and two new

restorations were inserted.

During the observation time, six fractures in the

ceramic material occurred. These can be divided into

two total and four partial fractures. In all cases, restor-

ations fractured at the connector between the retainer

and the pontic, but all retainer wings remained bonded

to the abutment teeth. In total fractures, the bridge

framework fractured at the mesial and distal connector.

The rst total fracture occurred during the rst year

after placement of the restoration, and the second after

a period of 4 years of clinical use. Both were replaced

during the observation period with similar restorations.

In partial fractures, only one of the two connectors frac-

tured. All partial fractures occurred between the fourth

and seventh years of clinical use. These fractured

RBFDPs remained in function as cantilevered restor-

ations during the observation time.

DISCUSSION

All-ceramic RBFDPs are used as a minimally invasive,

tooth-tissue loss preventing alternative for replacing

anterior teeth.34 They have been performed for many

years and have become a useful and recognized tech-

nique. Clinical indicators include intact abutment teeth,

a short edentulous span such as one missing tooth, and

minimal dynamic occlusal contacts on the abutment

teeth. The advantages of these restorations are numer-

ous and result from the combined advantages of com-

posite resins (adhesion, conservation of tooth substrate),

and ceramic (color stability, wear resistance, enamel-like

thermal expansion, and rened esthetics).21-32

This clinical study evaluated 54 In-Ceram anterior

RBFDPs with a conventional two-retainer design for 8

years. The results suggest that when the indications

and patient are selected appropriately, the overall out-

come and clinical behavior are satisfactory. In this study

the success rate for In-Ceram RBFDPs was 85.18% after

8 years.

Patient acceptance of the restorations at 8 years

was very encouraging. Only one patient complained

about a minor esthetic problem, because he had a

broad maxillary edentulous space and the pontic cre-

ated an asymmetrical appearance.

Table 3 Results of the clinical investigation

Category 1Y 2Y 4Y 6Y 8Y

Satised patient 48 48 48 48 48

Unsatised patient 1 1 1 1 1

Caries 0 0 0 0 0

Debonding 0 0 2 2 2

Total fractures 1 1 2 2 2

Partial fractures 0 0 2 3 4

13




During the observation time, two of the restorations

debonded. The explanation of this phenomenon per-

haps was related to the adhesive method used in this

study (silane application after air-abrasion only). Kern

and Thompson35 clearly showed in a laboratory study

on bonding methods to In-Ceram, that silane applica-

tion after air-abrasion of In-Ceram is inferior to silica

coating and silane application or to using phosphate

monomercontaining resins after air-abrasion. Also, a

critical factor is the composite resin cement. Degrada-

tion within the resin cement may be related to break-

down of the ller-resin interface bond, which could

contribute to resin cement failure.36 Many factors con-

tribute to this phenomenon, like the polymerization

shrinkage of composite resin, the dissolution of the

resin matrix of composite resins in oral uids, and the

loss of marginal integrity caused at baseline by poly-

merization shrinkage or by removal of cement ashes

with blunt instruments.37,38 In our study, both of the

debonded restorations were in the mandibular arch.

This may be attributable to the reason that moisture

control during cementation is more dicult to obtain

in the mandibular arch than in the maxillary arch. This

means that a substantial amount of extra chairtime

may be needed following the incorporation of a RBFDP,

and the use of rubber dam during cementation is

highly recommended. These two failures occurred 3

and 3.5 years after the insertion of the restorations.

Complications such as debonding are most likely to

occur with RBFDPs within a period of 5 years, with a 3%

mean annual debonding rate.39

Fractures of ceramic material occurred in six restor-

ations: two total fractures and four partial fractures. On

condition that the absence of any ceramic fracture is

chosen as a criterion for success, the success rate was

88.88%. Nevertheless, if functioning of the restorations

is considered a success (thus including the three-unit

and two-unit cantilever restorations) the success rate

was 96.29%. Other clinical studies have reported higher

and lower failure rates resulting from fracture (Kern and

Strub32 94.1% after 5 years of clinical service; Pjetursson

et al39 87.7% after 5 years; Wassermann et al40 92.3%

after 5 years). In all cases, restorations fractured at the

connector between the retainer and the pontic, but all

retainer wings remained bonded to the abutment

teeth. One of the main causes for failure of all-ceramic

RBFDPs is fracture of the connector area.29,31,32,41 To

achieve improved fracture strength, dierent frame-

work designs have been proposed. Pospiech at al42,43

suggested a design with two proximal grooves (0.8 to

1.0 mm 4.0 mm) and a connector with increased

dimensions (4.0 2.0 mm minimum). Also, rounded

edges and little interdental separation were signicant

for stress reduction. Kern at al44 concluded that the

fracture strength of all-ceramic RBFDPs fabricated with

In-Ceram substructure was signicantly improved by

the addition of small proximal box preparations to the

abutments, and veneer applied to the In-Ceram frame-

work circumferentially instead of only labially. In our

study, the connectors of the frameworks were designed

to be as thick as possible, and a shallow box prepar-

ation was made in each abutment proximally to the

pontic side (dimensions approximately 2 2 0.5 mm)

The four partial fractures in this study occurred

between the fourth and seventh years of clinical use, but

these fractured RBFDPs remained in function as cantile-

vered restorations during the observation time. Clinical

and in vitro studies have reported that high-strength

oxide ceramics used as a cantilever restoration is a viable

alternative for anterior tooth replacement.29,32,40,45-48

These results may not be surprising if one considers the

mechanics of tooth movement. Dierential movement

of the abutment teeth in a two-retainer RBFDP during

occlusal excursive movements causes shear and torque

forces on the pontic and connectors, resulting in a frac-

ture, bending, debonding, or stress at the resin-RBFDP

interface.29,36,46

CONCLUSION

This study evaluated 54 In-Ceram anterior RBFDPs with

a conventional two-retainer design for 8 years. The suc-

cess rate was 85.18 % after 8 years. The results suggest

that when the indications and patient are selected

appropriately, the overall outcome and clinical behav-

ior are satisfactory. Further research should be directed

14




toward the potential indications, ecacy, and progno-

sis of this type of prosthesis.

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