Abstract
Purpose
The aim of this follow-up study was to report the long-term outcome of all-ceramic cantilever resin-bonded fixed dental prostheses (RBFDPs).
Materials and methods
In 16 patients (mean age of 33.3 ± 17.5 years) 22 RBFDPs made from a glass-infiltrated alumina ceramic (In-Ceram) were inserted with a phosphate monomer containing luting agent after air-abrasion of the retainer wings. The abutment preparation included a shallow groove on the cingulum and a small proximal box. The restorations replacing 16 maxillary and 6 mandibular incisors were followed over a mean observation time of 188.7 months.
Results
No restoration debonded. Two RBFDPs fractured and were lost 48 and 214 months after insertion, respectively. The 10-year and 15-year survival rates were both 95.4% and dropped to 81.8% after 18 years.
Conclusion
Anterior all-ceramic cantilever RBFDPs exhibited an excellent clinical longevity.
1
Introduction
All-ceramic resin-bonded fixed dental prostheses (RBFDPs) have been introduced in the early nineties of last century as treatment options for missing incisors . Unfortunately, all-ceramic RBFDPs with two conventional retainers showed a relatively high fracture rate within the first year of clinical service . However, often unilaterally fractured RBFDPs remained in situ as cantilever RBFDPs over five and ten years .
As a result of the positive clinical survival of the unilaterally fractured RBFDPs, in 1997 all-ceramic cantilever RBFDPs were suggested as an even more conservative treatment approach . The cantilever design reduces shear and tensile forces that result from splinting two abutment teeth with differential movements that occur in the conventional RBFDP design with two retainers . This reduces the risk of (unilateral) debonding with a high caries risk if the debonding is unperceived or ignored by the patient . In contrast cantilever RBFDPs will lose their retention when its retainer debonds so that the patient will immediately notice it.
During a observation time of ten years all-ceramic cantilever RBFDPs showed a better survival rate than two-retainer all-ceramic RBFDPs , which is in agreement with data on metal-ceramic RBFDPs . For metal-ceramic cantilever RBFDPs excellent long-term survival rates after 10 years (91%) and even after 15 years (84%) have been reported . In another clinical trial with 13 metal-ceramic cantilever RBFDPs replacing maxillary incisors the survival rate was actually 100% after 18 years . Comparable long-term data for all-ceramic cantilever RBFDPs are still absent.
Therefore, it was the aim of this follow-up report to present the long-term outcome of anterior all-ceramic cantilever RBFDPs over a period of up to 18 years.
2
Materials and methods
Sixteen patients (16 males and 6 females, mean age of 33.3 ± 17.5 years) with 22 missing incisors were included in the study. Fourteen incisors were congenitally missing, while 8 teeth were lost due to traumatic incidences or other reasons. Twenty-two anterior cantilever resin-bonded fixed dental prostheses ( Table 1 ) were fabricated from the glass-infiltrated alumina ceramic In-Ceram using the Celay copy-milling technique. RBFDPs frameworks were made from In-Ceram alumina (N = 14) or from In-Ceram zirconia containing about 26% zirconia (N = 8) . All RBFDPs were veneered with Vitadur-Alpha (both ceramics from Vita, Bad Säckingen, Germany).
| Central incisors | Lateral incisors | Total | |
|---|---|---|---|
| Maxilla | 0 | 16 | 16 |
| Mandible | 4 | 2 | 6 |
| Total | 4 | 18 | 22 |
The alumina ceramic frameworks consisted of one lingual retainer wing with a connector to the pontic. The minimal connector dimensions of the ceramic frameworks were 2 mm in horizontal thickness and 3 mm in vertical height. The minimal thickness of the retainer wings was 0.5–0.7 mm. No antagonistic contacts on the pontics during lateral or protrusive movements of the mandible were allowed.
The abutment preparation was strictly within the enamel and included a lingual veneer, a shallow groove on the cingulum and a small proximal box preparation (dimensions: 2 mm × 1 mm × 0.5 mm) . The preparation did not provide any mechanical retention but allowed definite positioning of the restoration during luting ( Fig. 1 ).
The RBFDPs ( Figs. 2 and 3 ) were inserted between 1996 and 2001 using a phosphate monomer containing luting resin (Panavia 21 TC, Kuraray) . Prior to resin application, the bonding surfaces of the retainers were airborne particle-abraded for 15 s. (50 μm alumina particles at 0.25 MPa pressure) and the enamel was etched for 30 s with phosphoric acid after rubber dam isolation.
Patients were recalled every year for a clinical examination to evaluate the restorations with regard to function and possible failures. Patients who moved out of the region and could not present for a clinical evaluation were contacted by phone and interviewed about the function of the restoration and asked to send clinical photos by mail for evaluation.
Using the Kaplan and Meier method 15 the survival rate of the restorations was analysed using a statistical software programme (Statistix 10, Analytical Software, Tallahassee).
2
Materials and methods
Sixteen patients (16 males and 6 females, mean age of 33.3 ± 17.5 years) with 22 missing incisors were included in the study. Fourteen incisors were congenitally missing, while 8 teeth were lost due to traumatic incidences or other reasons. Twenty-two anterior cantilever resin-bonded fixed dental prostheses ( Table 1 ) were fabricated from the glass-infiltrated alumina ceramic In-Ceram using the Celay copy-milling technique. RBFDPs frameworks were made from In-Ceram alumina (N = 14) or from In-Ceram zirconia containing about 26% zirconia (N = 8) . All RBFDPs were veneered with Vitadur-Alpha (both ceramics from Vita, Bad Säckingen, Germany).
