journal of dentistry 42 (2014) 660–663
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Survival of anterior cantilevered all-ceramic resin-bonded fixed dental prostheses made from zirconia ceramic Martin Sasse *, Matthias Kern Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University, Arnold-Heller Str. 16, 24105 Kiel, Germany
Objectives: This study evaluated the clinical outcome of all-ceramic resin-bonded fixed
Received 2 September 2013
dental prostheses (RBFDPs) with a cantilevered single-retainer design made from zirconia
Received in revised form
9 February 2014
Methods: Forty-two anterior RBFDPs with a cantilevered single-retainer design were made
Accepted 26 February 2014
from yttrium oxide-stabilized zirconium oxide ceramic. RBFDPs were inserted using Panavia 21 TC as luting agent after air-abrasion of the ceramic bonding surface. Results: During a mean observation time of 61.8 months two debondings occurred. Both
RBFDPs were rebonded using Panavia 21 TC and are still in function. A caries lesion was
detected at one abutment tooth during recall and was treated with a composite filling.
Therefore, the overall six-year failure-free rate according to Kaplan–Meier was 91.1%. If only
Fixed dental prostheses
debonding was defined as failure the survival rate increased to 95.2%. Since all RBFDPs are
still in function the overall survival rate was 100% after six years.
Conclusions: Cantilevered zirconia ceramic RBFDPs showed promising results within the
observation period. Clinical Significance: Single-retainer resin-bonded fixed dental prostheses made from zirconia ceramic show very good mid-term clinical survival rates. They should therefore be considered as a viable treatment alternative for the replacement of single missing anterior teeth especially as compared to an implant therapy. # 2014 Elsevier Ltd. All rights reserved.
The use of zirconia ceramic in dental practices around the world increased strongly in recent years. High fracture strength and fracture toughness1 makes it suitable for the fabrication of frameworks of fixed dental prostheses. Further on cantilevered all-ceramic resin-bonded fixed dental prostheses (RBFDPs) might * Corresponding author. Tel.: +49 431 597 2874; fax: +49 431 597 2860. E-mail address: [email protected]
(M. Sasse). http://dx.doi.org/10.1016/j.jdent.2014.02.021 0300-5712/# 2014 Elsevier Ltd. All rights reserved.
also benefit from using zirconia ceramic. So far, high long-term survival rates of RBFDPs made from alumina ceramic have been reported.2,3 Case reports on zirconia ceramic RBFDPs can be found in the literature.4 However except for few studies5,6 no data on the clinical outcome of zirconia ceramic RBFDPs is available. The aim of this paper was to provide further data on the clinical outcome of densely sintered zirconia ceramic made, single-retainer, all-ceramic RBFDPs with a cantilevered design.
journal of dentistry 42 (2014) 660–663
This is of special interest since there still is some controversy among the scientific community on how stable and reliable the bond strength to zirconia ceramic is in the long-term clinical use. Various bonding techniques to zirconia ceramic are being utilized clinically nowadays and were discussed in the literature7,8 therefore clinical data on longterm stability is of outmost importance. The purpose of this report is reveal the medium- to longterm outcome of cantilevered single-retainer all-ceramic RBFDPs made from densely sintered zirconia ceramic after a clinical service time of at least 3 years.
Materials and methods
Thirty-seven consecutive patients with the indication for anterior RBFDPs received 42 anterior restorations made from zirconia ceramic with a cantilevered single-retainer design. RBFDPs replaced either upper (61.9%, n = 26) or lower (38.1%, n = 16) incisors. Table 1 shows descriptive statistics of measured baseline characteristics. Most of these RBFDPs replaced missing upper lateral incisors (n = 22, 52.4%) or lower central incisors (n = 13, 31.0%). In three patients, each receiving two cantilevered RBFDPs replacing maxillary lateral incisors, the restorations were produced as mesially splinted RBFDPs to provide long-term retention after orthodontic closure of a diastema mediale. These three RBFDP frameworks were splinted in the mesial proximal contact area of the retainerwings and both laterals were cantilevered distally. The preparation of the abutment teeth (Fig. 1a) was done as described in previous publications5,6 (an oral veneer preparation with a notch and a proximal box).9,10 Using a polyether material (Permadyne, 3 M ESPE; Seefeld, Germany) with a simultaneous dual-mix technique, impressions were taken. Since a fully computer-aided-designing of RBFDP frameworks was not supported by the software, the frameworks were modelled manually in resin (Pattern Resin, GC Europe) and wax and were scanned. The zirconia frameworks were then produced using the Cerec inLab 3D CAD/CAM system (Sirona, GER). They were milled out of pre-sintered zirconia ceramic blocks and afterwards they were densely sintered in a special
Table 1 – Patient/tooth characteristics. Characteristic
No. of patients (n) Male Female Mean age (y) (SD) Tooth replaced (FDI) 11 21 12 22
37 17 25 32.7 (19.4) 1
Maxilla total 31 41 32 42
26 6 7 1 2
3 11 11
Fig. 1 – (a) Preparation of a lower lateral incisor for a singleretainer RBFDP replacing the missing central incisor. (b) Final try-in of the veneered restoration before bonding.
furnace. After try-in the frameworks were veneered with IPS e.max Ceram (Fig. 1b). The adhesive cementation procedure using the autocuring resin Panavia 21 TC followed a standardized procedure. The bonding surfaces of the retainer wings were air-abraded with 50 mm alumina particles at 0.25 MPa.11 While air-abrading, the veneering ceramic was shielded by a temporary resin coating (Pattern Resin, GC Corporation, J).12 Afterwards the restorations were ultrasonically cleaned in 97% isopropyl alcohol. Rubberdam was applied and the tooth surfaces were cleaned with an air polishing system using a water-soluble sodium bicarbonate cleaning powder. The enamel was etched with 36% phosphoric acid for 30 s, rinsed with water spray and air dried. RBFDPs were adhesively luted with the phosphate monomer containing composite resin Panavia 21 TC applied directly onto the air-abraded ceramic surface. Times until debonding, failure or censoring (i.e. last followup examination, Fig. 2) were recorded. Statistical analysis was made using SPSS software.13,14
Within a mean observation period of 61.8 months (min. 37.2, max. 123.5) two debondings and one biological complication occurred in the 42 RBFDPs.
journal of dentistry 42 (2014) 660–663
Fig. 2 – Oral view of a zirconia ceramic RBFDP after 2 years of clinical service.
Fig. 4 – Kaplan–Meier analysis demonstrating the survival of the RBFDPs regarding debonding as failure.
Both debondings occurred after about 11 months. The first debonding occurred in one of the splinted RBFDPs and the patient was not able to tell exactly when and how the debonding took place. In this case only one retainer wing debonded, but due to the splinted design the RBFDP stayed in place. The framework was cut into two single pieces transforming the twosplinted RBFDPs into two separate RBFDPs. The debonded RBFDP was then rebonded using the same procedure. The second debonding occurred when a patient accidently got hit in the face with an elbow by her preschool age daughter while playing. This RBFDP was successfully rebonded as well. In both cases resin leftovers could be found partly on the enamel surface and partly on the retainer wing in a comparable amount. Failures were of adhesive cause but partly off the tooth and partly off the ceramic surface. A caries lesion was detected at one abutment tooth during recall at 61.4 months. It was treated with a small composite filling. Therefore, the overall six-year failure-free rate according to Kaplan–Meier15 was 91.1% (Fig. 3). Considering debonding as (partial) failure the success rate was 95.2% after 6 years (Fig. 4). No catastrophic failures occurred. Since after reinsertion of the two debonded restorations all RBFDPs were still in function, after six years the survival rate of the RBFDPs was 100%.
No statistically significant difference could be found when comparing the rate of failure free RBFDPs replacing upper versus RBFDPs replacing lower incisors (Maxilla 84%, N = 26; Mandible 100%, N = 16, Gehan–Wilcoxon, p = 0.14, Fig. 5). Regarding the type of RBFDP, whether it was the regular single type or a splinted design, a statistically significant difference could be found (single type 93%, N = 39; splinted 67%, N = 3, Gehan–Wilcoxon, p = 0.03, Fig. 6). This difference has to be regarded with great caution though because of the very small number of splinted RBFDPs within the study.
Fig. 3 – Kaplan–Meier analysis demonstrating the rate of failure-free RBFDPs.
Fig. 6 – Failure free rate of single type RBFDPs and splinted RBFDPs.
Fig. 5 – Failure free rate of RBFDPs in the maxilla and mandible.
journal of dentistry 42 (2014) 660–663
The high survival rate of the zirconia ceramic RBFDPs in this study is in agreement with previous results reported in the literature on this kind of restoration2,3,5,6,16. In this study two debondings occurred, one of which was related to traumatic impact and therefore cannot be considered as a failure of the dental restoration by intended use. The second debonding occurred at one of three splinted RBFDPs of this study. Again this compares well with the results on two-retainer RBFDPs which were reported to be inferior to single-retainer RBFDPs3. It might be assumed that the decreased survival of the two-retainer RBFDPs relates to the differential movement of the abutment teeth which induces a shear force on the retainer wing. This shear force might finally lead to the debonding of the RBFDP. The splinted RBFDPs probably undergo this differential movement of the abutment teeth as well and might possibly therefore show inferior survival rates. None of the reported complications led to the final loss of the RBFDP. Even though two debondings were recorded within the observation period, after rebonding of the RBFDPs their intended function was not impaired. None of the frameworks fractured even at traumatic impact. In a previous study, dependent on the design all-ceramic RBFDP were sometimes subject to fracture when made from aluminium oxide ceramics.17 Such fractures could not be found using zirconia ceramic with the design used in this study. Single-retainer cantilevered zirconia ceramic RBFDPs showed very promising results during six years of clinical service. It remains to be seen how RBFDP survival will turn out over longer-term observation. However, according to the results of this study, the use of single-retainer all-ceramic RBFDPs can be recommended for the anterior region only. Whether this concept might also work for the replacement of canines or premolars is still unknown. Regarding the replacement of molars a cantilevered RBFDP cannot be recommended; however the use of a modified inlay-retained zirconia FDP might be a promising alternative approach.18
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