Clinical evaluation of fiber-reinforced fixed bridges

Fatigue Resistance of Dissected Lower First Molars Restored with Direct Fiber-Reinforced Bridges—An In Vitro Pilot Study

The aim of this research was to evaluate the mechanical impact of utilizing different fiber-reinforced composite (FRC) systems to reinforce inlay-retained bridges in dissected lower molars with different levels of periodontal support. A total of 24 lower first molars and 24 lower second premolars were included in this study. The distal canal of all molars received endodontic treatment. After root canal treatment, the teeth were dissected, and only the distal halves were kept. Standardized class II occluso-distal (OD) (premolars) and mesio-occlusal (MO) (dissected molars) cavities were prepared in all teeth, and premolar–molar units were created. The units were randomly distributed among four groups (n = six/group). With the aid of a transparent silicone index, direct inlay-retained composite bridges were fabricated. In Groups 1 and 2, both discontinuous (everX Flow) and continuous (everStick C&B) fibers were used for reinforcement, while in Groups 3 and 4, only discontinuous fibers (everX Flow) were used. The restored units were embedded in methacrylate resin, simulating either physiological periodontal conditions or furcation involvement. Subsequently, all units underwent fatigue survival testing in a cyclic loading machine until fracture, or a total of 40,000 cycles. Kaplan–Meyer survival analyses were conducted, followed by pairwise log-rank post hoc comparisons. Fracture patterns were evaluated visually and with scanning electron microscopy. In terms of survival, Group 2 performed significantly better than Groups 3 and 4 (p < 0.05), while there was no significant difference between the other groups. In the case of impaired periodontal support, a combination of both continuous and discontinuous short FRC systems increased the fatigue resistance of direct inlay-retained composite bridges compared to bridges that only contained short fibers. Such a difference was not found in the case of sound periodontal support between the two different bridges.

Comparison of Different Restoration Techniques for Endodontically Treated Teeth

The aim of the present study is to evaluate the physical properties of endodontically treated teeth restored with five different restorative techniques and materials. Hundred and forty extracted human molar teeth were used. In addition to five restoration groups, specimens with no restorations were used as the negative control, and intact molar teeth were used as the positive control. For flexural strength tests, material specimens were made from 5 different materials using a mould according to ISO 4049 standards. One-way ANOVA revealed that the fracture resistance was significantly affected by the restoration type. SFRC group showed the best fracture resistance values, while lowest values were seen in the GWF group. The test results of flexural strength showed values between 140 and 184 MPa and modulus of elasticity between 6.33 and 18.89 GPa ( $p<0.05$ ). Under the limits of this study, results showed that SFRC can be used to increase the fracture resistance of ETT.

Scanning electron microscopy assessment of the load-bearing capacity of cad/cam-fabricated molar crowns

Although fiber-reinforced composites are commonly used in dental practice, whether fiber-reinforced crowns and fixed partial dentures can be used as definitive prostheses remains to be determined. This study used scanning electron microscopy to evaluate the load-bearing capacity of non-reinforced and fiber-reinforced composite (FRC) molar crowns prepared by computer-aided design/computer-aided manufacturing (CAD/CAM). The crowns were fabricated from three empirical FRC blocks, one empirical composite block, and one commercial ceramic block. The FRC resin was prepared by mixing BaO silicate particles, E-glass fiber, and dimethacrylate resin. Specimens were divided into five groups (n = 10), differing in the amounts of filler, resin, and fiber. Crowns were statically loaded until fracture. One-way analysis of variance and Tukey's post hoc multiple comparison tests were used for statistical analyses. The groups showed significant differences in load-bearing capacity; empirical bidirectional FRC resin blocks had the highest capacity, while commercial ceramic blocks had the lowest capacity. Molar crowns formed from FRC resin blocks had higher load-bearing capacity compared to non-reinforced composite resin and ceramic blocks. These results show that fiber reinforcement increased the load-bearing capacity of molar crowns.

Comparison of Load-Bearing Capacities of 3-Unit Fiber-Reinforced Composite Adhesive Bridges with Different Framework Designs

Background

The aim of this study was to investigate and compare the load-bearing capacities of three-unit direct resin-bonded fiber-reinforced composite fixed dental prosthesis with different framework designs.

Material/Methods

Sixty mandibular premolar and molar teeth without caries were collected and direct glass fiber-resin fixed FDPs were divided into 6 groups (n=10). Each group was restored via direct technique with different designs. In Group 1, the inlay-retained bridges formed 2 unidirectional FRC frameworks and pontic-reinforced transversal FRC. In Group 2, the inlay-retained bridges were supported by unidirectional lingual and occlusal FRC frameworks. Group 3, had buccal and lingual unidirectional FRC frameworks without the inlay cavities. Group 4 had reinforced inlay cavities and buccal-lingual FRC with unidirectional FRC frameworks. Group 5, had a circular form of fiber reinforcement around cusps in addition to buccal-lingual FRC frameworks. Group 6 had a circular form of fiber reinforcement around cusps with 2 bidirectional FRC frameworks into inlay cavities. All groups were loaded until final fracture using a universal testing machine at a crosshead speed of 1 mm/min.

Results

Mean values of the groups were determined with ANOVA and Tukey HSD. When all data were evaluated, Group 6 had the highest load-bearing capacities and revealed significant differences from Group 3 and Group 4. Group 6 had the highest strain (p>0.05). When the fracture patterns were investigated, Group 6 had the durability to sustain fracture propagation within the restoration.

Conclusions

The efficiency of fiber reinforcement of the restorations alters not only the amount of fiber, but also the design of the restoration with fibers.

An overview of development and status of fiber-reinforced composites as dental and medical biomaterials

Fibr-reinforced composites (FRC) have been used successfully for decades in many fields of science and engineering applications. Benefits of FRCs relate to physical properties of FRCs and versatile production methods, which can be utilized. Conventional hand lamination of prefabricated FRC prepregs is utilized still most commonly in fabrication of dental FRC devices but CAD-CAM systems are to be come for use in certain production steps of dental constructions and medical FRC implants. Although metals, ceramics and particulate filler resin composites have successfully been used as dental and medical biomaterials for decades, devices made out of these materials do not meet all clinical requirements. Only little attention has been paid to FRCs as dental materials and majority of the research in dental field has been focusing on particulate filler resin composites and in medical biomaterial research to biodegradable polymers. This is paradoxical because FRCs can potentially resolve many of the problems related to traditional isotropic dental and medical materials. This overview reviews the rationale and status of using biostable glass FRC in applications from restorative and prosthetic dentistry to cranial surgery. The overview highlights also the critical material based factors and clinical requirement for the succesfull use of FRCs in dental reconstructions.

Metal free, full arch, fixed prosthesis for edentulous mandible rehabilitation on four implants

PURPOSE

The goal of this work is to describe an implant-prosthetic protocol for rehabilitation of edentulous mandible, by using a fixed prosthesis made of fiber-reinforced composite material (FRC). The protocol contemplates a minimal invasive surgery and ensures predictable and safe results, with good aesthetic and performance combined to cost savings.

METHODS

FRC material is used to build the substructure of a prosthetic framework supported by four short implants (5mm long and 4mm wide). The prosthesis substructure is made of Trinia immersed in a matrix of epoxy resin (FRC). It is supplied in milling blocks (pre-cured) for the CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Implants are placed in lower edentulous jaw in position of first molar and canine, each side. Four month after, a resin bar is build based on a stone model, denture teeth are placed and the occlusion is checked. The resin bar and the stone model with milled abutments are scanned and a FRC bar is achieved with the CAD/CAM technique. The teeth are mounted to the substructure trough denture resin. Temporary cementation of framework is achieved on the abutments connected to the implants.

CONCLUSION

A protocol for a fixed mandibular implant-prosthetic rehabilitation is described. The protocol contemplates a minimal invasive surgery and ensures predictable and safe results, with good aesthetic and performance combined to cost savings. In addition, this technique allows performing basic surgery also in presence of atrophy.

Mechanical properties of orthodontic wires on ceramic brackets associated with low friction ligatures

Abstract Introduction Few studies investigated the mechanical properties of orthodontic wires on ceramic brackets associated the ligatures. Objective This study aimed to compare the load-deflection of orthodontic wires with round section of 0.016” made of stainless steel (SS), nickel-titanium (NiTi) and glass fiber-reinforced polymer composite (GFRPC). Material and method Sixty specimens obtained from 10 sectioned pre-contoured arches (TP Orthodontics), were divided into 3 groups of 20 according to each type of material (1 esthetic-type wire and 2 not esthetic) and length of 50 mm. The methodology consisted of a 3-point bending test using esthetic ceramic brackets (INVU, TP Orthodontics, Edgewise, 0.022”x 0.025”) as points of support. The tensile tests were performed on a mechanical test machine, at a speed of 10 mm/min, deflection of 1 mm, 2 mm and 3 mm. Friedman’s Non Parametric Multiple comparisons test was used (P<0.05). Result The nickel-titanium wire presented smaller load/ deflection compared with stainless steel. GFRPC wires had lower strength values among all groups evaluated (P<.05). The steel wire showed permanent deformation after 3 mm deflection, NiTi wire demonstrated memory effect and the esthetic type had fractures with loss of strength. Conclusion It can be concluded that steel wires have high strength values, requiring the incorporation of loops and folds to reduce the load / deflection. NiTi and GFRPC wires produced low levels of force, however the esthetic wire was shown to fracture and break.

Comparison of fiber reinforcement placed at different locations of pontic in interim fixed partial denture to prevent fracture: An in vitro study

BACKGROUND

The interim restoration is an important phase in fixed prosthodontic therapy. It should provide sufficient durability to withstand the forces of mastication. A fractured interim restoration is damaging to the prosthodontic care and may lead to an unscheduled appointment for repair. Several attempts have been made to reinforce interim fixed partial dentures (FPDs). These have included the use of metal wire, a lingual cast metal reinforcement, a processed acrylic resin interim restoration, and different types of fibers, e.g., carbon, polyethylene, nylon and glass. These fibers can be placed in the occlusal, middle or cervical thirds in the FPD. There is no scientific data to evaluate the effect of fiber placement methods on the fracture resistance of clinical interim FPDs.

PURPOSE OF THE STUDY

Hence this study was designed to evaluate fracture load values of interim FPDs with different locations of fiber reinforcement.

MATERIALS AND METHODS

30 interim FPD samples with polymethyl methacrylate (PMMA) reinforced with fibers at three different locations mainly occlusal, cervical and middle (10 samples each) were fabricated using a metal FPD on a master die. They were tested for fracture resistance in universal testing machine.

RESULTS

The fracture resistance was recorded and is tabulated and analyzed statistically. The results showed that the placement of the reinforcement in the occlusal third of the pontic resulted in higher fracture resistance which was significantly higher (P < 0.05) than all other locations.

CONCLUSION

The occlusal third of the pontic region from mesial to the distal end of the connector is the best site of placement of the fiber for reinforcing the PMMA interim restorative resin.

Fiber reinforced composites in prosthodontics - A systematic review

Fiber-reinforced composite (FRC), prostheses offer the potential advantages of optimized esthetics, low wear of the opposing dentition and the ability to bond the prosthesis to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: Fiber-composites to build the substructure and hybrid or micro fill particulate composites to create the external veneer surface. This article reviews the various types of FRCs and its mechanical properties.

Fiber-reinforced Composite Resin Bridge: A Treatment Option in Children

A number of treatment options, ranging from Maryland bridges to implants, are available for the replacement of congenitally or traumatically missing permanent anterior teeth. But, there are several limitations of these therapeutic options when they have to be used before the completion of the growth, particularly in children. Reinforcement of composite resins with polyethylene fibers significantly improves their mechanical properties. Fiber-reinforced composite (FRC) bridge can offer a good alternative to conventional treatment options in replacing a missing permanent anterior tooth until a more definitive prosthesis can be provided at the end of the growth period. The purpose of this article is to present a clinical case of a single tooth replacement utilizing noninvasive and metal free fixed FRC bridge in a 13 years old child as an interim treatment option. How to cite this article: Gupta A, Yelluri RK, Munshi AK. Fiber-reinforced Composite Resin Bridge: A Treatment Option in Children. Int J Clin Pediatr Dent 2015;8(1):62-65.

A review of the success and failure characteristics of resin-bonded bridges

OBJECTIVES

This literature review was designed to assess and compare the success rates and modes of failure of metal-framed, fibre-reinforced composite and all-ceramic resin-bonded bridges.

MATERIALS AND METHOD

A Medline search (Ovid), supplemented by hand searching, was conducted to identify prospective and retrospective cohort studies on different resin-bonded bridges within the last 16 years. A total of 49 studies met the pre-set inclusion criteria. Success rates of 25 studies on metal-framed, 17 studies on fibre-reinforced composite and 7 studies on all-ceramic resin-bonded bridges were analysed and characteristics of failures were identified.

RESULTS

The analysis of the studies indicated an estimation of annual failure rates per year to be 4.6% (±1.3%, 95% CI) for metal-framed, 4.1% (±2.1%, 95% CI) for fibre-reinforced and 11.7% (±1.8%, 95% CI) for all-ceramic resin-bonded bridges. The most frequent complications were: debonding for metal-framed, resin-bonded bridges (93% of all failures); delamination of the composite veneering material for the fibre-reinforced bridges (41%) and fracture of the framework for the all-ceramic bridges (57%).

CONCLUSIONS

All types of resin-bonded bridges provide an effective short- to medium-term option, with all-ceramic performing least well and having the least favourable mode of failure. The methods of failures were different for different bridges with metal frameworks performing the best over time.

A conservative treatment approach to replacing a missing anterior tooth

An implant-supported crown or conventionally fixed partial denture is the most common treatment modality to replace a missing anterior tooth but a more conservative approach, with a fiber reinforced composite resin FPD, can be used to replace a missing anterior tooth in young patients or when the patient does not agree for an implant, or conventional FPD or RPD therapy. It is an esthetic, conservative single sitting chairside procedure which can be used as a definitive treatment alternative in certain clinical situations for esthetic and functional replacement of a missing anterior tooth. To achieve desirable results, putty matrix was used for proper positioning of the pontic during direct fabrication of FRCFPD.

Esthetic rehabilitation of single anterior edentulous space using fiber-reinforced composite

A fiber-reinforced composite (FRC) fixed prosthesis is an innovative alternative to a traditional metal restoration, as it is a conservative treatment method. This case report demonstrates a detailed procedure for restoring a missing anterior tooth with an FRC. A 44-year-old woman visited our department with an avulsed tooth that had fallen out on the previous day and was completely dry. This tooth was replanted, but it failed after one year. A semi-direct technique was used to fabricate a FRC fixed partial prosthesis for its replacement. The FRC framework and the pontic were fabricated using a duplicated cast model and nanofilled composite resin. Later on, interproximal contact, tooth shape, and shade were adjusted at chairside. This technique not only enables the clinician to replace a missing tooth immediately after extraction for minimizing esthetic problems, but it also decreases both tooth reduction and cost.

A systematic review of outcome measurements and quality of studies evaluating fixed tooth-supported restorations

PURPOSE

The purpose of this systematic review was to review clinical studies of fixed tooth-supported prostheses, and to assess the quality of evidence with an emphasis on the assessment of the reporting of outcome measurements. Multiple hypotheses were generated to compare the effect of study type on different outcome modifiers and to compare the quality of publications before and after January 2005.

MATERIALS AND METHODS

An electronic search was conducted using specific databases (MEDLINE via Ovid, EMBASE via Ovid, Cochrane Library) through July 2012. This was complemented by hand searching the past 10 years of issues of the Journal of Oral Rehabilitation, Journal of Prosthetic Dentistry, Journal of Prosthodontics, and the International Journal of Prosthodontics. All experimental and observational clinical studies evaluating survival, success, failure, and complications of tooth-supported extracoronal fixed partial dentures, crowns, and onlays were included. No restrictions on age or follow-up time were placed.

RESULTS

The electronic search generated 14,869 papers, of which 206 papers were included for full-text review. Hand-searching added 23 papers. Inclusion criteria were met by 182 papers and were included for the review. The majority were retrospective studies. Only 8 (4.4%) were randomized controlled trials. The majority of the studies measured survival and failure, and few studies recorded data on success; however, more than 60% of the studies failed to define survival, success, and failure. Many studies did not use any standardized criteria for assessment of the quality of the restorations and, when standardized criteria were used, they were modified, thereby not allowing for comparisons with other studies. There was an increase of 21.8% in the number of studies evaluating outcome measurements of all-ceramic restorations in past 8 years.

CONCLUSIONS

Prosthodontic literature presents with a reduced percentage of RCTs compared to other disciplines in dentistry. The overall quality of recording prosthodontic outcome measurements has not improved greatly in the past 8 years.

Esthetic treatment of a periodontal patient with prefabricated composite veneers and fiber-reinforced composite: clinical considerations and technique

The advances in periodontal therapy and the clinical success of adhesive dentistry have changed the way dentists treat periodontal patients. As more teeth are saved, the demand for functional and esthetic restoration of periodontally involved teeth grows. Once, these teeth were restored with full-coverage splinted restorations, whereas today, adhesive techniques provide less invasive and less complicated treatment options. This paper presents a novel adhesive combination of fiber-reinforced composite and prefabricated composite veneers to restore function and esthetics in a periodontal patient with severe bone and attachment loss. After successful completion of the periodontal treatment, fiber-reinforced composite has been bonded to the buccal surface of the maxillary anterior teeth in order to control teeth mobility. At the same appointment, prefabricated composite veneers have been bonded to the splinted teeth in order to restore esthetics. The final result shows full integration of contemporary adhesive techniques for single-appointment, minimally invasive treatment of a periodontal patient.

CLINICAL SIGNIFICANCE

This paper describes the use of fiber-reinforced composite and prefabricated composite veneers for the treatment of severe periodontal patients with a minimally invasive, single-appointment technique.

Load-bearing capacity of fiber reinforced fixed composite bridges

OBJECTIVE

The aim of this study was to evaluate the reinforcing effect of differently oriented fibers on the load-bearing capacity of three-unit fixed dental prostheses (FDPs).

MATERIALS AND METHODS

Forty-eight composite FDPs were fabricated. Specimens were divided into eight groups (n = 6/group; codes 1-8). Groups 1 and 5 were plain restorative composites (Grandio and Z100) without fiber reinforcement, groups 2 and 6 were reinforced with a continuous unidirectional fiber substructure, groups 3 and 7 were reinforced with a continuous bidirectional fiber and groups 4 and 8 were reinforced with a continuous bidirectional fiber substructure and continuous unidirectional fiber. FDPs were polymerized incrementally with a handheld light curing unit for 40 s and statically loaded until final fracture.

RESULTS

Kruskal-Wallis analysis revealed that all groups had significantly different load-bearing capacities. Group 4 showed the highest mean load-bearing capacity and Group 7 the lowest.

CONCLUSION

The results of this study suggest that continuous unidirectional fiber increased the mechanical properties of composite FDPs and bidirectional reinforcement slowed crack propagation on abutments.

Single visit replacement of maxillary canine using fiber-reinforced composite resin

Missing a canine is of serious concern in social life of a patient in most of societies. While conventional fixed partial dentures and implant-supported restorations may often be the treatment of choice, fiber-reinforced composite (FRC) resins offer a conservative, fast and cost-effective alternative for single and multiple teeth replacement. This clinical report presents two cases where FRC technology was successfully used to restore canine edentulous area in terms of esthetic-cosmetic values and functionality.

An evaluation of fracture resistance of interim fixed partial denture fabricated using polymethylmethacrylate and reinforced by different fibres for its optimal placement: an in vitro study

BACKGROUND

Polymethylmethacrylate (PMMA) is the most common material used to fabricate interim fixed partial denture (FPD). Several attempts have been made to improve fracture strength of this material with various methods of reinforcement, but its effect on the fracture resistance of interim FPD was not evaluated.

METHOD

The study was designed in two stages. In the first stage various methods of reinforcement (glass fibre, polyethylene, combination of glass and polyethylene, and stainless steel) for interim FPD of PMMA were used and its effect on the fracture resistance of interim FPD was evaluated by three point bending test using universal testing machine. In the second stage, fibres which showed the highest fracture resistance value was used to ascertain the most appropriate site of placement for reinforcing interim FPD. Comparisons were made with analysis of variance.

RESULTS

Stainless steel and glass fibres showed significantly higher fracture resistance value than polyethylene alone or mixed with glass fibres (P < 0.001). Fibre placement in the occlusal third region of the pontic resulted in higher fracture resistance than the other locations (P < 0.05).

CONCLUSION

There was a definite improvement in the fracture resistance after reinforcement with fibres and stainless steel. The occlusal third region of the pontic is the most appropriate site of placement for reinforcement in interim FPD.

Resin-bonded fiber-reinforced composite for direct replacement of missing anterior teeth: a clinical report

Missing anterior teeth is of serious concern in the social life of a patient in most of societies. While conventional fixed partial dentures and implant-supported restorations may often be the treatment of choice, fiber-reinforced composite (FRC) resins offer a conservative, fast, and cost-effective alternative for single and multiple teeth replacement. This paper presents two cases where FRC technology was successfully used to restore anterior edentulous areas in terms of esthetic values and functionality.

Fixed partial dentures in an up to 8-year follow-up

Information on the longevity of fiber-reinforced composite fixed partial dentures (inlay FPDs) should be considered in the selection of materials, operative techniques and patient instructions related to prognosis and long-term cost-effectiveness.

Model system for measuring the effects of position and curvature of fiber reinforcement within a dental composite

PURPOSE

The aim of this study was to compare the effect of fiber curvature and position on flexural strength (FS), toughness, and elastic modulus in a dental flowable composite test specimen.

METHODS AND MATERIALS

Test specimens made of composite resin (Denfil Flow) were reinforced with preimpregnated glass fibers (Interlig). Control specimens (group A) did not contain fiber reinforcement. Fibers were placed with different positions and orientations into the test specimens (2 mm x 2 mm x 25 mm) (groups B, C, D). The test specimens (n = 10) were stored in distilled water for 3 days at 37 degrees C before testing in a three-point loading test (ISO 10477) at a crosshead speed of 1 mm/min to determine FS, flexural modulus (FM), and toughness. Data were analyzed with 1-way analysis of variance and Tukey HSD (sigma= 0.05).

RESULTS

The FM varied from 4.7 +/- 0.5 to 6.7 +/- 0.5 GPa. The lowest flexural strength and toughness values in reinforced specimens resulted from compression side fiber reinforcement (132 +/- 12 MPa, 21 +/- 4 MJ) and the highest from curved fiber reinforcement (174 +/- 8 MPa, 83 +/- 28 MJ), though this was not statistically significant from tension-side reinforcement. Although the toughness of the curved reinforced group was significantly higher than other groups, the flexural strength of curved reinforcement was not significantly higher than tension-side reinforcement.

CONCLUSION

Position and fiber orientation influenced the flexural strength, FM, and toughness. The most effective in increasing toughness was curved placement of fibers.

Fiber-reinforced fixed partial dentures: a preliminary retrospective clinical study

The aim of this study was to evaluate the clinical performance (retention rate) of fiber-reinforced composite fixed partial dentures (FPDs). Polyethylene fiber (Ribbond®) was used combined with restorative composite during FPDs fabrication. FPDs were placed in thirteen patients in a private clinic. Nineteen FPDS were evaluated. The prosthetic space was filled with only one pontic using extracted teeth (2 cases), acrylic resin teeth (11 cases), or with composite resin (6 cases), combined with Polyethylene fiber. The clinical criterion used was based on retention rate of FPDs. If FPDs were in function in the mouth at the time of examination without previous repair they were classified as Complete Survival (CS) restorations. A classification of Survival with Rebonding (SR) was assigned in the event of an adhesive failure, but after rebonding the FPD still remained under evaluation. Treatment was classified as a Failure (F) if the FPD restoration was lost. The time of evaluation was 41.15 months (±15.13). The FPDs evaluated were retained (CS=94.75%), and no failure was found except for in one situation which required rebonding (SR=5.25%). According to the survival estimation method of Kaplan-Meyer the mean survival time was 42.3 months. At the time of evaluation investigated, polyethylene-reinforced FPDs showed a favorable retention rate in preliminary data.

The effect of different restoration techniques on the fracture resistance of endodontically-treated molars

AIM

This study compared the fracture resistance of endodontically-treated mandibular molars with mesio-occluso-distal (MOD) cavities restored using different restoration techniques.

METHODOLOGY

Sixty sound extracted mandibular molars were randomly assigned to six groups (n=10). Group 1 did not receive any preparation. The teeth in Groups 2-6 received root canal treatment and a MOD cavity preparation. The teeth in Group 2 were kept unrestored. Group 3 was restored conventionally with amalgam. Group 4 was restored with a dentin bonding system (DBS, Clearfil SE Bond) and resin composite (CR) (Clearfil Photoposterior). Group 5 was restored with indirect hybrid ceramic inlay material (Estenia). In Group 6, polyethylene ribbon fiber (Ribbond) was inserted into cavities in a buccal-to-lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens, except for Group 2, were loaded to failure by a chewing simulation device (60,000 cycles x 50 N load, 1.3 Hz frequency) in an artificial environment at 37 degrees C. Each tooth was subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/minute. The mean loads necessary to fracture were recorded in Newtons and the results were statistically analyzed.

RESULTS

The mean fracture values were as follows: Group 1: 2485.3 +/- 193.98a, Group 2: 533.9 +/- 59.4a, Group 3: 1705.8 +/- 135.7a, Group 4: 2033.3 +/- 137.6cd, Group 5: 2121.3 +/- 156.5d, Group 6: 1908.9 +/- 132.2cd. There were statistically significant differences between the groups annotated with different letters. Thus, Group 1 (intact teeth) had the greatest fracture resistance and Group 2 (non-restored teeth) the poorest. No statistically significant differences were found between Groups 3 (amalgam), 4 (resin composite) and 6 (polyethylene ribbon fiber reinforced composite) (p > 0.05). Group 5 (indirect hybrid ceramic inlay) had greater fracture resistance than Group 3 (p < 0.05).

CONCLUSIONS

Within the limitations of this study, although all of the restoration groups were stronger than the prepared-only group, none of the restoration techniques tested was able to completely restore the fracture resistance lost from MOD cavity preparation. However, use of indirect hybrid inlay restorations in these teeth may be recommended, because this restoration technique indicated more favorable fracture failure modes than other restoration techniques used in this study and particularly greater fracture strength than amalgam restorations. The promising result of indirect hybrid inlay restorations may need to be confirmed by long-term clinical studies.

Effect of a new restoration technique on fracture resistance of endodontically treated teeth

The aim of the study was to investigate the effect of a new fiber-reinforced composite restoration technique on fracture resistance in endodontically treated premolars. Eighty sound extracted human mandibular premolars were assigned to four groups (n = 20). Group 1 did not receive any treatment. In groups 2, 3 and 4, the teeth received root canal treatment and a mesio-occluso-distal cavity preparation. Group 2 was kept unrestored. Group 3 was restored with a dentin bonding system and composite resin. In group 4, a piece of polyethylene ribbon fiber was inserted into the groove in a buccal to lingual direction during the restoration of teeth with dentin bonding system and composite resin. After finishing and polishing, the specimens were stored in 100% humidity at 37 degrees C for 24 h and placed at an angle of 45 degrees to the long axis of the tooth and subjected to compressive loading in a universal testing machine at a crosshead speed of 0.5 mm min(-1). The load necessary to fracture the samples was recorded in Newton (N) and submitted to Kruskal-Wallis anova and Mann-Whitney U-test. The fracture strength of the teeth reinforced with a combination of polyethylene fiber and composite resin were not significantly different than those that were restored with only composite resin (P > 0.05). However, most of the failure modes of the reinforced teeth were limited to the level of the enamel, while the other three groups showed fractures generally at the level of the dentin, cemento-enamel junction or more below (P < 0.05). Therefore, polyethylene ribbon fiber-reinforced composite resin restorations seemed a more reliable restorative technique than traditional composite restorations for extensive cavities.

Force levels of fiber-reinforced composites and orthodontic stainless steel wires: a 3-point bending test

INTRODUCTION

The purpose of this study was to evaluate the force levels of 2 sizes (diameters, 0.6 and 1.2 mm) of fiber-reinforced composites (FRCs) (Ever Stick; Stick Teck Ltd, Turku, Finland) compared with orthodontic stainless steel wires (sections, 0.016, 0.018, 0.017 x 0.025, and 0.019 x 0.026 in) under the same testing conditions.

METHODS

The samples were divided into 12 groups, each consisting of 10 specimens. Each sample was evaluated with a 3-point bending test on a universal testing machine. The FRC groups were light-cured by hand with a halogen curing unit (Optilux 501; SDS Kerr, Danbury, Conn) for 40 seconds. Groups 1 through 6 were tested at 1-mm deflection, and groups 7 through 12 at 2-mm deflection.

RESULTS

The results of ANOVA indicated significant differences among the various groups (P = .000). The post-hoc test showed that the 2-mm deflection groups had significantly higher load values than the 1-mm deflection groups (P = .000). The highest force levels were recorded with the 1.2-mm FRCs, followed by the 0.019 x 0.026-in stainless steel wires. No significant differences were found between the 0.6-mm FRCs and the 0.017 x 0.025-in wires. The lowest load values were reported with the 0.016-in stainless steel wires.

CONCLUSIONS

The 1.2-mm FRCs showed higher load values than the other stainless steel wires and the FRCs, whereas no significant difference was found between the 0.6-mm FRCs and the 0.017 x 0.025-in stainless steel wires. Thus, FRCs can be considered a viable esthetic alternative to full-size stainless steel wires to rigidly join dental segments to form anchorage units or units for active tooth movement.

Flexure strength evaluation of a laboratory-processed fiber-reinforced composite resin

STATEMENT OF PROBLEM

A fiber-reinforced composite resin system has been introduced for posterior restorations; however, little information is known regarding possible degradation of its flexure strength with respect to aging and cyclic loading.

PURPOSE

The aim of this in vitro study was to determine whether the fiber reinforcement improved the flexure strength of an indirect composite resin aged in air and water for 3 months and then subjected to static and cyclic loading.

MATERIAL AND METHODS

The materials tested in this study, non-fiber-reinforced composite resin (n=160) (Tescera Dentin) and fiber-reinforced composite resin (n=160) (Tescera U-beam and Rod), were fabricated as bars, 25.0 x 4.5 x 4.5 mm, and polished with 120- to 320-grit silicon carbide grinding paper. The static (n=15) and cyclical (n=25) flexure strengths (MPa) of specimens were tested initially and after 3 months' aging in air and water. The specimens were tested in 3-point loading in their respective aging media at a loading rate of 2 mm/min. Cyclic testing followed the staircase approach of either 1000 cycles or until specimen fracture. Statistical analysis for the static-loaded specimens consisted of a 3-way analysis of variance (media, aging, and fiber-reinforced versus unreinforced) (alpha=.05), whereas the cyclic-loaded specimens used confidence levels of .95 for the respective variables (media, aging, and fiber-reinforced versus unreinforced) and to compare static versus cyclic loading.

RESULTS

The statistical analysis of the static specimens showed no significant difference between control (unaged) groups and aged groups and aging media, but a significant difference (P<.001) between reinforced versus unreinforced specimens. For the cyclic-loaded specimens, the confidence levels at .95 showed no difference between control (unaged) groups and aged groups and aging media (air or water), but a difference between reinforced versus unreinforced specimens, and static-loaded versus cyclic-loaded specimens. During testing, the specimens separated into several pieces when the fiber reinforcement was on the compressive side, whereas the specimen remained intact when the fiber reinforcement was on the tensile side.

CONCLUSIONS

When compared to indirect composite resin without fiber reinforcement, the addition of fibers is an effective method to improve the flexure strength of indirect composite resin for the materials tested.

Reinforcing effect of glass-fiber-reinforced composite on flexural strength at the proportional limit of denture base resin

OBJECTIVE

To evaluate the reinforcing effect of fiber-reinforced composite (FRC) on flexural strengths at the proportional limit (FS-PL) of a denture base resin.

MATERIAL AND METHODS

Bar-shaped acrylic resin specimens and maxillary acrylic resin complete denture specimens were fabricated. The FS-PL of the reinforced bar-shaped specimens was tested. Novel FRC, FibreKor, Remanium, Palatal Bar Wire, and Clasp-Wire were used as reinforcing materials. Likewise, the compressive strength at the proportional limit (CS-PL) of the reinforced maxillary denture specimens was tested.

RESULTS

The FS-PL of the bar-shaped specimens reinforced with the FRCs was significantly higher than that of the unreinforced specimens. The FS-PL of the bar-shaped specimens reinforced with the 1.0-mm-thick FRC was similar to the FS-PL of specimens reinforced with Remanium or Palatal Bar Wire. The FS-PL of specimens reinforced with the 1.5-mm-thick FRC was significantly higher than with the metal-reinforcing materials. The reinforcing efficiency of the 1.0-mm-thick FRC was 1.78-1.79 and of the 1.5-mm-thick FRC 3.14-3.27. The reinforcing effect of the FRC on the CS-PL of the maxillary denture specimen was similar to the effect on the FS-PL of the bar-shaped specimens. The reinforcing efficiency was 1.40 for the 1.0-mm-thick FRC and 1.67 for the 1.5-mm-thick FRC.

CONCLUSION

The unidirectional glass-fiber-reinforced composite had a reinforcing effect on the flexural strength at the proportional limit of the denture base resin.

Developing meaningful systematic review of CAD/CAM reconstructions and fiber-reinforced composites

OBJECTIVE

Clinical literature was examined for evidence supporting use of CAD/CAM reconstructions and fiber-reinforced materials.

MATERIALS AND METHODS

Potential evidence was identified via databases [PubMed; EMBASE (R) Drugs & Pharmacology; Center for Reviews and Dissemination, University of York; Cochrane Library], hand search of non-indexed literature, secondary reference searches, and personal contacts with clinical trial PI's. Search terms included: dental restorations; CAD/CAM; CEREC; LAVA; CERCON; Procera; inlay/onlay; dental prosthesis; fiber-reinforced composite (FRC).

RESULTS

Two randomized-controlled clinical trials were identified as examined in one Cochrane Collaboration review relevant to CAD/CAM inlays. One systematic review of 15 CAD/CAM inlay studies was examined. Six studies were identified of three commercial FRC endodontic posts and eight reported on FRC use for fixed denture prostheses. Fifteen ongoing prospective trials were identified studying CAD/CAM fabricated zirconia-based prostheses. A total of 76 papers were referenced including those related to use of in vitro measures as evidence.

CONCLUSIONS

Review of the Cochrane analysis raised concerns that typical RCT protocols may prove insufficient for stratification of confounding variables (patient, practitioner, material) when treatment outcomes are primarily prosthesis- or material-based (not patient-based, e.g., as in fracture). RCT designs are most straightforward when treatment outcomes are patient-based (e.g., soft tissue changes). When treatment responses are material-based, controls also become difficult to define and studies become tests of equivalency/superiority; where well-stratified cohort designs are likely preferred. Large numbers of independent cohort studies support the use of CAD/CAM ceramic inlay/onlay restorations and crowns but many complications inhibit the application of high-level systematic review. Except perhaps for fiber-based endodontic posts, the clinical FRC literature appears insufficient for expert review. Single in vitro measures cannot currently serve as evidence for clinical practice, except in limited cases of simple function (e.g., impression material accuracy). Batteries of in vitro measures are often applied during materials development but cannot substitute for clinical study.

Use of short fiber-reinforced composite with semi-interpenetrating polymer network matrix in fixed partial dentures

OBJECTIVES

The aim of this study was to determine the static load-bearing capacity of fixed partial dentures (FPDs) made of experimental composite resin (FC) with short fiber fillers and interpenetrating polymer network (IPN) polymer matrix.

MATERIALS AND METHODS

Experimental composite FC resin was prepared by mixing short E-glass fibers (3mm in length) of 22.5wt% and IPN-resin 22.5wt% with silane treated silica fillers 55wt%. Four groups of FPDs (3-unit) were fabricated (n=6); Group A: made from commercial composite resin (Sinfony dentin, 3M-ESPE, control), Group B: Sinfony and fiber-reinforced composite (FRC) substructure, Group C: made from FC, Group D: made from FC with 1mm surface layer of Sinfony. The bridges were polymerized with a hand-light curing unit for 40s then post-cured in vacuum curing device (Visio Beta) for 15min before they were statically loaded with speed of 1mm/min until fracture. Failure modes were visually examined. Data were analyzed using ANOVA (p=0.05).

RESULTS

ANOVA revealed that bridges made from experimental fiber composite had statistically significantly higher load-bearing capacity (2171N) (p<0.05) than the control restorations (1482N).

SIGNIFICANCE

Restorations made from short glass fiber containing composite resin with IPN-polymer matrix showed better load bearing capacity than in those made with conventional composites resin and similar with those reinforced with FRC-substructure.

Fiber-reinforced composites in fixed partial dentures

Fiber-reinforced composite resin (FRC) prostheses offer the advantages of good aesthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinforcement in the fabrication of laboratory or chairsidemade composite-fixed partial dentures of conventional preparation. Other applications of FRC in dentistry are briefly mentioned. The possibilities fiber reinforcement technology offers must be emphasized to the dental community. Rather than limiting discussion to whether FRC prostheses will replace metal-ceramic or full-ceramic prostheses, attention should be focused on the additional treatment options brought by the use of fibers. However, more clinical experience is needed.

The influence of electron beam irradiation on fibre-reinforced composite specimens

This study investigated whether glass fibre-reinforced composite (FRC) specimens can benefit from post-curing using electron beam irradiation. Twenty-four frameworks of the Vectris and 24 of the Stick glass fibre-reinforced system were veneered with their correspondent veneer materials. Eight specimens of both systems were post-cured using electron beam irradiation (3 x 33 kGy, 10 MeV). The specimens were fixed in a restrained-end apparatus and inserted in an artificial mouth. With the exception of controls (n = 8 each) all other groups were thermally cycled and mechanically loaded (TCML). Finally, all samples were loaded to fracture using a universal testing machine. In two of eight non-irradiated Vectris/Targis specimens facing fracture occurred during TCML. Irradiation avoided these failures. No Stick/Sinfony facing fractured. However, Stick frameworks showed considerable torsions. Post-curing with electron beam irradiation made Stick frameworks stiffer. The fracture load of irradiated Stick/Sinfony specimens reached 520 +/- 31 N; control (without TCML and irradiation) 396 +/- 14 N, TCML-group without irradiation 362 +/- 41 N. Irradiated Vectris/Targis had a fracture resistance of 575 +/- 57 N; the control 556 +/- 36 N and the TCML group without irradiation 383 +/- 51 N. This investigation demonstrated that different types of FRC systems could considerably benefit from electron beam irradiation. The reconstructions became stiffer and resisted higher load.

Clinical performance of posterior metal-free polymer crowns with and without fiber reinforcement: one-year results of a randomised clinical trial

OBJECTIVES

The aim of this study was to evaluate the clinical performance of posterior, metal-free polymer crowns with and without a glass-fiber framework, in comparison to metal-ceramic crowns.

METHODS

After randomisation, 80 single crowns, manufactured from a newly designed polymer composite, were set in posterior teeth. Half of these received a glass-fiber framework, while half were prepared without any framework stabilisation. All polymer crowns were adhesively luted with resin cement. As the control group, 40 conventional metal-ceramic crowns were inserted with hybrid cement. Documentation included failures and other complications, as well as gingival/plaque status and aesthetic performance.

RESULTS

During the 12-month observation period, eight polymer crowns and three metal-ceramic crowns showed clinically relevant complications. The most frequent complications were root canal treatments (n=4) and decementation (n=4) of the crowns. A total of two crowns (one polymer crown with fiber network and one crown of the control group) had to be replaced. After 12 months, polymer crowns with glass-fiber framework exhibited significantly higher plaque accumulation (p=0.005) and gingival index (p=0.04) than metal-ceramic crowns, while no significant differences could be demonstrated for polymer crowns without fiber reinforcement. Postoperative sensibility and aesthetic performance did not differ significantly between the groups.

CONCLUSIONS

Within a 12-month observation period, posterior polymer crowns with and without glass-fiber framework demonstrated acceptable stability and aesthetic performance. Polymer crowns with fiber framework showed significant higher plaque accumulation and gingival index than metal-ceramic crowns.

Fracture Resistance of Inlay-retained Fixed Partial Dentures Reinforced with Fiber-reinforced Composite

In this study, the effect on the fracture load of inlay-retained composite fixed partial dentures (FPDs) caused by reinforcing them with fiber-reinforced composite (FRC) in different positions was examined. Experimental FPDs were fabricated using Estenia/EG Fiber (Kuraray Medical). Pontic reinforcement was then performed in one of the following three ways: reinforced the central area in a single line or in double straight lines, or reinforced the bottom in a curved line. The finding was that, when the area ranging from the connector to the bottom of the pontic was reinforced with FRC in a curved line, the fracture load of the FPDs tended to become higher. In addition, the FPDs fractured mainly at the veneering composite of the connector area. Based on the results of this study, it was concluded that reinforcement using FRC is effective, and that the veneering composite in the connector area needs to have sufficient strength to prevent the fractures.

Damage mechanics and load failure of fiber-reinforced composite fixed partial dentures

OBJECTIVES

Damage mechanics has been defined as the study of the initiation (initial failure) and accumulation of damage to and including rupture (final failure). This study was designed to evaluate the effect of increasing fiber-reinforced composite (FRC) substructure within a standardized fixed partial denture (FPD) model on the failure performance, in terms of damage mechanics.

METHODS

The two FRC restorative systems, Targis/Vectris (TV) (Ivoclar Vivadent) and EverStick (ES) (Stick Tech with Gradia, GC Corp.), were used to restore the molar FPD model (1.5 mm axial and 2.0 mm occlusal reduction). Templates were used to standardize substructure designs with 0, 18, 43, and 66% cross-sectional FRC volume fraction (V(FRC)) of fiber substructure. Specimens (n = 5) were homogenized at 29 points and stored for 1 week at 37 degrees C in distilled water. Specimens were luted with calcium hydroxide, then statically loaded until failure. Initial failure (IF), final failure (FF) and the mode of failure were recorded.

RESULTS

The lowest mean load to initial failure was 530 N (TV 18%) and the highest was 1208 N (ES 66%). Linear regression analysis calculated the Pearson's correlation coefficient (r) for the interactions between V(FRC) and IF (ES: r = 0.7879, TV: r = 0.6184), V(FRC) and FF (ES: r = 0.912, TV: r = 0.8152), and between IF and FF (ES: r = 0.892, TV: r = 0.7237). Unreinforced specimens universally fractured instantaneously.

SIGNIFICANCE

The highest loads to initial and final failure were yielded by specimens with the highest cross-sectional V(FRC).

Chairside Replacement of Posterior Teeth Using a Prefabricated Fiber-Reinforced Resin Composite Framework Technique: A Case Report

The fixed replacement of a single posterior missing tooth for those patients who cannot have either implants or conventional laboratory-generated fixed prostheses has always been a challenge to clinicians. The development of fiber-reinforced composites (FRCs) has opened up new possibilities of chairside treatment options to manage these types of clinical situations. Techniques using FRCs as frameworks with traditional restorative resin composites as veneering materials can provide chairside fixed prostheses that are esthetic and potentially durable, with minimal abutment tooth loss. A clinical case is presented that will illustrate a novel concept for tooth replacement--the use of an FRC prefabricated framework--to allow for a single visit, chairside replacement of a missing molar. The assembly of the framework and the clinical steps used in the framework placement and pontic fabrication are shown in detail.

CLINICAL SIGNIFICANCE

The combination of FRC technology and adhesive techniques can provide minimally invasive and cost-effective treatment options for the chairside replacement of missing posterior teeth.

Evaluation of two matrix materials intended for fiber-reinforced polymers

Two matrix resins for fiber composites that remain in a fluid state during storage and handling before polymerization were evaluated. The resin mixtures, based on methyl methacrylate (MMA), were produced with two different cross-linking agent systems: 1,4-butanediol dimethacrylate and ethylene glycol dimethacrylate or diethylene glycol dimethacrylate. Water sorption, water solubility, water uptake and residual MMA monomer were determined. Thermomechanical analysis was used to determine linear dimensional changes as a function of temperature. Flexural strength and modulus as well as fracture work and the maximum stress intensity factor were determined. The results revealed similar values for both matrix polymers regarding water sorption, water solubility, water uptake, residual MMA monomer (0.5 wt% (+/- 0.03)) and coefficient of linear thermal expansion. Flexural strength for polymer B was 68.7 MPa (+/- 9.8) compared to 56.0 MPa (+/- 13.3) for polymer A when tested dry and 64 MPa (+/- 6.1) compared to (54 MPa (+/- 3.3) when water-saturated. Fracture toughness tests showed higher maximum stress intensity factor values for polymer B (0.75 +/- 0.17) MPa x m1/2 than for polymer A (0.55 +/- 0.12) MPa x m1/2. The resin binders showed an appropriate consistency while remaining in a fluid state during storage and manipulation.