|Year : 2012 | Volume
| Issue : 3 | Page : 174-178
The clinical survival rate of the FRC inlays prosthetic restorations in the evaluation period of seven years
Nedim Smajkic1, Amra Vukovic2, Selma Zukic2, Anita Bajsman2, Fahrudin Mucic1
1 Department of Dental Pathology and Endodontics, Faculty of Dental Medicine with Clinics of Sarajevo University, Bolnicka 4 Sarajevo, Bosnia and Herzegovina
2 Preclinical Dentistry, Faculty of Dental Medicine with Clinics of Sarajevo University, Bolnicka 4 Sarajevo, Bosnia and Herzegovina
|Date of Web Publication||11-Jun-2013|
Department of Dental Pathology and Endodontics, Faculty of Dental Medicine with Clinics of Sarajevo University, Bolnicka 4 Sarajevo
Bosnia and Herzegovina
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims: In this study, a sample of 28 patients followed the clinical functionality and durability of inlay fiber-reniforced composite (FRC) bridge restorations, laboratory fabricated, for a period of 7 years. Materials and Methods: Patients with the loss of a first molar in the posterior region were selected for the study. Fabrications of FRC structures were made of longitudinal and woven fibers and ceramic optimized polymer material was used for veneering. Statistical Analysis Used: The restorations were evaluated using the modified United States Public Health Service (USPHS) parameters system for the clinical evaluation of dental restorative materials. Kaplan-Meier survival test was used for analyzing the data. Results: During the evaluation period, no fracture of the FRC construction was found. At all tested restorations, significant color change of the Ceromer veneering material was observed. During the investigation time, the color of the restorations became slightly lighter, with loss of gloss. In two patients, a chip off from the veneered material was noticed after 4 years, in three patients over 5 years and in three patients after 6 years. Conclusions: FRC-Ceromer inlay fixed prosthetic restorations for a period of 7 years showed acceptable clinical durability and functionality.
Clinical Relevance to Interdisciplinary Dentistry
Fiber reinforced composite inlay restorations for a period of seven years showed exceptional durability and functionality with minimal preparation of the abutment teeth. FRC restorations present an acceptable alternative to the classical construction of the metal ceramic or full ceramic bridge which needs to make preparation with extensive reduction of the abutment teeth.
Keywords: Composite veneering, fiber-reinforced composite, inlay bridge
|How to cite this article:|
Smajkic N, Vukovic A, Zukic S, Bajsman A, Mucic F. The clinical survival rate of the FRC inlays prosthetic restorations in the evaluation period of seven years. J Interdiscip Dentistry 2012;2:174-8
|How to cite this URL:|
Smajkic N, Vukovic A, Zukic S, Bajsman A, Mucic F. The clinical survival rate of the FRC inlays prosthetic restorations in the evaluation period of seven years. J Interdiscip Dentistry [serial online] 2012 [cited 2022 Jul 1];2:174-8. Available from: https://www.jidonline.com/text.asp?2012/2/3/174/113247
Presentation at a Meeting: Third Dental Days of Bosnia and Hercegovina with International Participation 2009
Organisation: Faculty of Dental Medicine with Clinics of Sarajevo University
Place: Sarajevo, Bosnia and Herzegovina
Date: 8-10 October 2009
| Introduction|| |
With increased demand for minimally invasive aesthetic and tissue preservation, prosthetic restorations for replacing one or two missing teeth and reduced treatment costs, development of fiber-reinforced composite (FRC) offered the dental profession the possibility of fabricating resin-bonded, aesthetically acceptable and metal-free tooth restorations. The unique technology of fiber reinforcement enables, in dentistry, for the first time, the production of non-metallic translucent frameworks for crowns and bridges. Fiber-reinforced technology is being used in aircraft construction and shipbuilding. This method of construction is used where a low weight is required from materials with a certain elasticity and considerable stress distribution during continuous high load. Ceramic optimized polimer (Ceromer) for veneering dentin and enamel tooth structure combines the aesthetic appearance of ceramic, easy use of synthetic materials and similar abrasion like natural enamel. FRC-Ceromer restorations are fixed to the abutment teeth with two inlays made in connection with the bridge, which are cemented with resin cement in the existing cavities.
With the FRC fixed partial dentures (FPDs), there are two approaches on the use of the fibers: One is based on laboratory-made restorations while the other is based on using the fibers in chair-side direct restorations. The FRC constructions made in the laboratory provide better strength and veneer exhibit better physical properties and aesthetics than do direct placement FRC restorations.
Many studies have focused on the improvement of FRC FPD strength. The most accepted concept to produce FRC FPDs is based on the use of continuous unidirectional glass fibers in the dimethacrylate resin matrix as a substructure for the FPD.
In the dental literature, there are currently a limited number of clinical studies on the fiber-reinforced FPDs mostly made by the direct technique. ,,,, However, based on those results, it is assumed that FRC prostheses have considerable longevity, especially with those made by the laboratory technique. Although short-term clinical data exist for resin-bonded, glass FRC FPDs, long-term data are needed.
The aim of this paper is to follow the clinical functionality and durability of inlay FRC bridge restorations, laboratory fabricated, for a period of 7 years, on a sample of 28 patients.
| Materials and Methods|| |
For the study, patients were selected with the loss of a first molar tooth in the posterior region. All patients selected for research were with similar personal habits, proper oral hygiene and non-smokers. After testing the vitality and the radiograph analysis of teeth that need to serve as bridge abutments, old fillings and secondary caries were removed. Inlay cavities were prepared as class second (occlusal-proximal cavity). The depth of the cavity after preparation is 2 mm in the occlusal and proximal directions. Proximal preparation ends with gingival line, and, if possible, 1 mm above the gingiva. A proximal cavity dimension of the occlusal surface to the gingival margin is at least 3 mm to meet the thickness of the FRC connector design for fracture resistance. Teeth that have extensive fillings over 3 mm deep or advanced caries lesions below the gingival margin are not included for research. On completion of the preparation, a double impression is taken of both jaws with silicone impression material, followed by bite registration and color determination of the restoration.
An FRC structure was made of materials Vectris Pontic and Vectris Frame and veneering was done with Targis material (Ivoclar Vivadent AG, Scahaan, Liechtenstein). After receiving the restoration from the laboratory, the restoration was cemented into the cavity with resin cement (Maxcem, Kerr Corporation, Orange, CA, USA). Before cementation, the dentin and enamel surface were conditioned with total etch technique and the adhesives were applied (Optibond Solo Kerr Corporation). After removal of excess cement, occlusion and articulation were checked and complete restoration was polished with a silicone polisher. In the period of 7 years, all patients are recalled annually for inspection of the FRC inlay bridge restoration. On the recalls, the abutment teeth were checked for: Post-operative sensitivity, presence of secondary caries, tooth vitality, changes in the gingival tissue and marginal discoloration. The FRC structures were checked for fracture of the restoration and of the veneering material by: Wear due to articulation (surface texture), chip off and color stability. The vitality test was performed with an electric tester (Parkell, Edgewood, NY, USA). Checking of patients was done by five practitioners. The restorations were evaluated using criteria for clinical evaluation of dental restorative materials for use by United States Public Health Service (USPHS) modified by California Dental Assotiation for evaluating color, anatomic form and marginal characteristic and other functional properties. The scores were A (good), B (acceptable) and C (unacceptable). At the end of the evaluation period the scores were presented in percentage. The data of chipping of veneering material were analyzed with the Kaplan-Meier survival test (α = 0.05) software using MedCalc v12. 3.
| Results|| |
During the evaluation period, no fractures of the FRC construction were found [Figure 1]. For all 7 years during the evaluation, three cases of secondary caries on abutment teeth were found. Pulp vitality of all abutment teeth was at the normal level. Change in gingival tissue was not observed in any patient included in the sample. Eleven percent of the restorations after 5 years showed slight marginal discoloration at the occlusal and proximal surfaces of the inlay retainers. In two patients, a chip off from the veneered material was noticed after 4 years, three patients after 5 years and in three patients after 6 years [Figure 2] and [Figure 3], [Table 1].
|Figure 1: Fiber-reinforced composite inlay fixed partial denture 7 years after placement|
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|Figure 2: Kaplan-Meier survival test curve for a chip off of veneering material|
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|Table 1: Kaplan-Meier survival test for a chip off of veneering material|
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At all tested restorations, significant color change of the ceromer veneering material was observed. During the investigation time, the color of the restorations became slightly lighter with loss of gloss [Table 2].
| Discussion|| |
Fiber-reinforced frameworks with composite veneering materials offer a convenient, less-invasive solution for replacing one missing tooth. , There are few clinical studies on the behavior of FPDs, and most are short-term evaluations. ,,
A long-term clinical study was performed for 3, 4 and 5 years, which showed acceptable clinical result for more than 65% survival rate. ,,,
Bohlsen and Kern presented a 3-year prospective study of survival rate for FRC FPDs, and showed that it had a low survival rate because the restorations were cemented with temporary cement, zinc phosphate and glass ionomer cement.  Those cements are not suitable for cementation of FRC FPDs like metal ceramic restorations. FRC FPDs can be only cemented with resin luting cements. Chemical bonding between FRC and tooth structure, with the applied adhesive system, can be achieved only with a resin cement. The result of this long-term clinical research shows a satisfactory durability of all 28 treated patients. The aesthetics of composite veneering material shows satisfactory results. The best aesthetics was shown during first 3 years after placement. In some researches, the aesthetics of FRC composite restorations is described to be even better than with metal FPDs.  One hundred percent of the restorations was showed a slight loss of luster and the color of the restorations was changed to a slightly lighter shade after the third year. Twenty-five percent of the restorations showed loss of texture in the occlusal area after the third year. Eleven percent of the FPDs recorded the chip off of the veneering composite material in the occlusal regions of inlays and pontics. This could be the result of insufficient thickness of the veneering material. Those failures were successfully repaired intraorally with a composite material, which is an advantage of the FRC FPDs.  Small secondary caries were found in three cases 4 years after placement inlay FRC FPDs on occlusal areas, and these were successfully treated with a composite filling without removing or damaging the FPDs. Patients did not feel any post-operative sensitivity after placing the FRC FPDs. Significant changes in vitality test value were not found, and all teeth abutments during the investigation period had a positive vitality reaction. No inflammatory changes in the gingival tissue that came in contact with the FRC FPDs were found in all specimens in the evaluation period. Marginal discoloration was found in 11% of the restorations after 5 years. These discolorations are a result of the leakage between a restoration and tooth structure, and could be the result of polymerization shrinkage of resin cement on the surface.  Those marginal discolorations were found after 5 years. The occlusal load during 5 years could be also the reason for the same. We described it as being clinically acceptable. There are no records for inlay bridge debonding of the abutment teeth for all restorations in a period of 7 years. There is no evidence of any crack or fracture of the FRC frameworks during the evaluation period. The FRC framework is designed with the guidelines that the thickness of the framework cannot be less than 3 mm and, to avoid air bubbles left in the material structure, the framework is pressed under vacuum and is polymerized. The FRC framework made in this way in the laboratory has better fracture resistance than frameworks made chair side.  Fracture resistance is improved by using longitudinal fibers that are then coated with woven fibers, which are manufactory recommended. 
There were reports about fractures of veneering composite material in the pontic area. , The reason for those fractures could be in failures of framework design or in preparing the framework to receive veneering composite material. All FRC frameworks were sandblasted with aluminum oxide powder to produce the rough surface for microretention. It is also used to clean the frameworks from resin, which stays unpolimerized because of oxygen contact from air; this is also a manufactory recommendation.  After that, the framework was silanized and then the veneering material was applied. A result of this research shows that the FRC structure has a clinically excellent fracture resistance and tissue accessibility. This can be used for the fabrication of long-term FPDs. The veneering material shows excellent aesthetics during the period of 3 years. The veneering material showed aesthetical change that was caused with aging of the composite material and abrasion resistance after the third year, but this was still clinically acceptable. All 28 patients included in this clinical research showed satisfaction with the aesthetics and function of the FRC FPDs. During this evaluation, Targis veneering material was not available in the market, and it was changed with the new generation material. The new generations of composite veneering materials show better properties of aesthetics and wear resistance. The new indirect resin material demonstrated color stability at or below a quantitative level that would be considered clinically acceptable. Douglas (2000) presented a study with results that color changes of ceramic-polymers occurred because of changes in chroma, rather than because of alterations in lightness. New veneering resins demonstrated color stability that was not significantly different from the porcelain control.  Vectris material, which showed 100% survival rate for fracture resistance in clinical conditions, is also not available on the market. There are other companies that produce glass fibers in polymer matrix with similar properties and proper handling characteristics (Polydentia Swiss and Micerium Italy).
FRC veneered with Ceromer inlay fixed prosthetic restorations for a period of 7 years showed exceptional durability and functionality with minimal preparation of the abutment teeth. FRC-Ceromer inlay bridge restorations present an acceptable alternative to the classical construction of the metal ceramic or full ceramic bridge, which needs to be prepared with extensive reduction of the abutment teeth.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]