Fiber-reinforced Composite Restorations Research Articles

Clinical evaluation of posterior flowable short fiber-reinforced composite restorations without proximal surface coverage

The purpose of this clinical trail was to assess the clinical behavior of posterior composite restorations supported by a substantial foundation of flowable short fiber-reinforced composite SFRC (everX Flow, GC, Japan) used without proximal surface coverage with particulate filler resin composite (PFC). Seventy patients (20 males, 50 females; mean age: 30 ± 10 years) were randomly enrolled in this trial. Patients received direct restorations of either SFRC covered only on the occlusal surface (1–2 mm) by conventional PFC composite (G-ænial Posterior, GC), or plain conventional PFC composite without fiber-reinforcement, in Class II cavities in premolar and molar vital teeth. One operator made all restorations using one-step, self-etch bonding agent (G-ænial Bond, GC) according to manufacturers’ recommendations. Two blinded trained operators evaluated the restorations at baseline, at 6, 12 and 18 months using modified USPHS criteria. Results indicated that, in both groups and at different follow-up intervals, according to evaluated criteria, restorations were rated mostly with best score (Alpha) (p > 0.05). For the marginal integrity after 6 months, a single case in the intervention [increased to 3 (8.8%) after 18 months] and 3 (9.7%) cases of the control group [increased to 4 (12.9%) after 18 months] had Bravo score but with no significant difference (p > 0.05). For color match measured after 6 and 18 months, three (8.8%) cases had Bravo score in the intervention group. The use of flowable SFRC composite without any PFC surface coverage proximally in Class II restorations demonstrated satisfactory clinical outcome throughout the 18-month follow-up.

Fracture Resistance of Fiber-Reinforced Composite Restorations: A Systematic Review and Meta-Analysis.

Composite resin is universally used for posterior teeth restorations. Fibers have been suggested for the mechanical improvement of the restorations. This study assessed the fracture resistance of class II fiber-reinforced composite restorations and compared it with the fracture resistance of three control groups: (1) healthy teeth, (2) non-fiber-reinforced restorations and (3) unrestored cavities. A search was performed using PubMed, Web of Science and Google Scholar from 15 May to 12 June 2023. Only in vitro studies from the last 10 years were included for this systematic analysis. This study was registered in the PROSPERO database, it followed PRISMA guidelines and the risk of bias was assessed using the QUIN tool. Fracture resistance median values, in Newtons (N), were calculated for the experimental and control groups (95% confidence interval). For pairwise comparison, nonparametric tests (p < 0.05) were applied. Twenty-four in vitro studies met the inclusion criteria. The fracture resistance of the experimental group was 976.0 N and differed (p < 0.05) from all controls. The experimental group showed lower values of fracture resistance than healthy teeth (1459.9 N; p = 0.048) but higher values than non-fiber-reinforced restorations (771.0 N; p = 0.008) and unrestored cavities (386.6 N; p < 0.001). In vitro systematic outcomes evidenced that glass and/or polyethylene fibers improved the fracture resistance of composite restorations.

Fatigue performance of endodontically treated molars reinforced with different fiber systems.

The aim was to investigate the fatigue performance of root canal-treated (RCT) molars restored with different direct restorations utilizing discontinuous and continuous fiber-reinforced composite (FRC) systems. The impact of direct cuspal coverage was also evaluated. One hundred and twenty intact third molars extracted for periodontal or orthodontic reasons were randomly divided into six groups (n=20). Standardized MOD, regular cavities for direct restorations were prepared in all specimens, and subsequently, root canal treatment and root canal obturation was carried out. After the endodontic treatment, the cavities were restored with different fiber-reinforced direct restorations as follows: SFC group (control), discontinuous short fiber-reinforced composite (SFC) without cuspal coverage (CC); SFC+CC group, SFC with cuspal coverage; PFRC group, transcoronal fixation with continuous polyethylene fibers without CC; PFRC+CC group, transcoronal fixation with continuous polyethylene fibers with CC; GFRC group, continuous glass FRC post without CC; and GFRC+CC, continuous glass FRC post with CC. All specimens underwent a fatigue survival test in a cyclic loading machine until fracture occurred or 40,000 cycles were completed. The Kaplan-Meier survival analysis was conducted, followed by pairwise log-rank post hoc comparisons between the individual groups (Mantel-Cox). The PFRC+CC group was characterized by significantly higher survival compared to all the groups (p < 0.05), except for the control group (p = 0.317). In contrast, the GFRC group showed significantly lower survival compared to all the groups (p < 0.05), except for the SFC+CC group (p = 0.118). The control group (SFC) showed statistically higher survival than the SFRC+CC group (p < 0.05) and GFRC group (p < 0.05), but it did not differ significantly from the rest of the groups in terms of survival. Direct restorations utilizing continuous FRC systems (in the form of polyethylene fibers or FRC post) to restore RCT molar MOD cavities performed better in terms of fatigue resistance when CC was performed compared to the same FRC restorations without CC. On the contrary, teeth restored with SFC restorations performed better without CC compared to the ones where SFC was covered. In the case of fiber-reinforced direct restorations for MOD cavities in RCT molars, direct CC is recommended when utilizing long continuous fibers for reinforcement, however, should be avoided when only SFC is used for their reinforcement.

Clinical Effectiveness of Fiber-reinforced Composite Space Maintainer and Band and Loop Space Maintainer in a Pediatric Patient: A Systematic Review and Meta-analysis.

BackgroundObjectives: This systematic review aimed to evaluate the clinical effectiveness of fiber-reinforced composite space maintainer (FRCSM) and band and loop space maintainer (BLSM) in a pediatric patient.Materials and methodsEligibility criteria: Randomized controlled trials (RCTs) were conducted on 3–12-year-old children who received FRCSM and BLSM. Information sources: Literature search of electronic databases such as PubMed, Cochrane, and Google Scholar for the time period of 2000 to October 2020. Risk of bias: Cochrane collaboration's risk of bias tool was used to assess the risk of bias.ResultsIncluded studies: The search resulted in 147 published studies. After the removal of duplicate studies and full-text analysis, eight studies were selected. Synthesis of results: Fiber-reinforced composite restoration (FRCSM) was judged to be good for short-term space maintenance with good esthetics, less time-consuming, and good patient and parental acceptance. Meta-analysis was done for failure rate at 6 months and 12 months. After 6 months, the FRCSM group showed less failure, with a risk ratio of 0.83 (95% CI = 0.47–1.49; Z value = 0.61). However, after 12 months, the FRCSM group showed more failure, with a risk ratio of 1.30 (95% CI = 0.04–4.23; Z value = 0.44). Description of the effect: FRCSM performed better than BLSM for a short-term, i.e., around 6 months but after 12 months of space maintainer placement BLSM performed better than the FRCSM.DiscussionStrengths and limitations of evidence: The strength of this systematic review is its complete adherence to the PRISMA statement 2009. This review attempted to evaluate the effectiveness of FRCSM when compared with BLSM which has not been evaluated before. Additionally, only RCTs were included in this review adding to its validity. This review also included a meta-analysis that compared the failure rate at the 6th and 12th month. The main shortcoming of this systematic review is the limited number of databases searched and the limited number of existing studies. Interpretation: Within the limitations of this review, it can be stated that the FRCSM is an effective space maintainer for short-term space maintenance. However, it is necessary to conduct more RCTs with larger sample size, preferably using a split-mouth design to improve the longevity of FRCSM. Additionally, it is also necessary to standardize the technique of fabrication of FRCSM since an existing study showed high heterogeneity in the technique of fabrication.OtherFunding: None. Registration: The protocol of this systematic review was registered on PROSPERO (ID-CRD42020165831).How to cite this articleKamki H, Kalaskar R, Balasubramanian S, et al. Clinical Effectiveness of fiber-reinforced Composite Space Maintainer and Band and Loop Space Maintainer in a Pediatric Patient: A Systematic Review and Meta-analysis. Int J Clin Pediatr Dent 2021;14(S-1):S82–S93.

Survival Rates of Anterior-Region Resin-Bonded Fixed Dental Prostheses: An Integrative Review.

This study aimed to review clinical publications involving anterior-region resin-bonded fixed partial dentures to evaluate their survival rates vis-à-vis their materials and design. An electronic search was conducted using PubMed/MEDLINE to identify articles that reported on the longevity of anterior resin-bonded fixed dental prostheses published between 2000 and 2020. Only primary clinical studies that involved a follow-up after at least 3 years were included in this review. A statistical analysis was performed to evaluate resin-bonded fixed dental prostheses’ survival rates in relation to their materials and design. This review ultimately included 23 clinical publications, comprising prospective studies, retrospective studies, and randomized controlled trials. Its statistical analysis estimated the studied prostheses’ 5-year survival rate at 86.2% for metal-framed prostheses, 87.9% for zirconia prostheses, 93.3% for alumina prostheses, 100% for glass or ceramic prostheses, and 81.7% for fiber-reinforced composite restorations. Failure rates did not significantly differ between the different material groups or between the single- and double-retainer groups. Resin-bonded fixed dental prostheses present excellent 5-year clinical longevity in the anterior sector and a favorable benefit/risk/cost ratio. Currently, no consensus has been established on an ideal material for these restorations. Cantilever design tends to limit constraints on the prostheses’ retainers and, thus, increases their survival time. All-ceramic cantilever fixed partial dentures can be considered as a definitive therapy, given their high success and survival rates. They are an optimal solution for adolescents or young adults facing potentially continuous growth.

Fibre Reinforced Fixed Partial Denture for Periodontally Compromised Anterior Teeth

Aim: To describe a protocol to replace few missing anterior teeth with periodontally compromised abutments. Background: Due to their lower modulus of elasticity, fibre reinforced composites (FRCs) minimize the stress level at the tooth restoration interface and enable an adjustment of the framework’s mechanical properties by inserting adequate fibre volumes. Direct and semi-direct fabricated FRC Fixed Dental Prosthesis (FDP) now compete successfully with conventional cast metal resin-bonded FDPs. Case Description: A Fibre Reinforced Composite(FRC) bridge was given to replace missing 31 and 41. The FRC material was bonded from canine to canine (33-43) to ensure the stability of the periodontally compromised abutment teeth by acting as a splint with minimal intervention. Conclusion: Fiber-reinforced composite restorations reduce the number of appointments and make single visit dentistry possible especially when the abutments are periodontally compromised and require splinting. Clinical Significance: This case report demonstrates the benefits of splinting periodontally compromised abutment teeth.

Fiber-reinforced composite fixed dental prosthesis using an additive manufactured silicone index.

Digital tools such as facial and intraoral digitizers and additive manufacturing (AM) technologies assist restorative treatments. The objective of the present manuscript was to describe a workflow procedure for treatment planning and fabricating a fiber-reinforced composite fixed dental prosthesis (FDP) replacing an absent maxillary lateral incisor, using additively manufactured silicone indices to facilitate the clinical intervention. The elaboration of a direct fiber-reinforced composite restoration is a technique sensitive procedure which might be time-consuming for the clinician. The digital waxing helped to determine the exact position and size of the lingual wings and connectors of the fiber-reinforced FDP and to design a three-piece index. And the AM of the index helped to transfer the information to the patient's dentition accurately. The protocol minimizes the time of clinical intervention by facilitating the transference of the virtual diagnostic waxing teeth into the patient's mouth. The three-piece silicone index provides an individualized path of insertion of each index part while also providing a customized space and location of the lingual wings of the restoration. The usage of AM silicone indices facilitates the clinical intervention by translating the size and position of the diagnostic wax-up teeth into the patient's mouth, minimizing clinical procedure's time.

Fracture behavior of Bi-structure fiber-reinforced composite restorations

ObjectiveThe aim of this study was to evaluate the fracture-behavior of direct composite restorations made with two different composite-core materials. In addition, fracture toughness (FT), flexural strength (FS) and flexural modulus (FM) of tested composites were evaluated. MethodsTwenty groups of posterior crown restorations were fabricated (n = 6/group). The groups were made of a 4–5 mm layer of composite-core materials (everX Flow and SDR Flow+) and covered by a 2 mm layer of conventional composite (G-aenial Anterior & Posterior, G-aenial Universal Injectable, Essentia, CeramX, Filtek Z500). Control groups were only made of conventional composites or composite-core materials. Crowns were statically loaded until fracture. Failure-modes were then visually examined. FT, FS and FM were determined for each tested composite (n = 6). ResultsANOVA revealed that crown restorations made only from everX Flow composite had significantly higher load-bearing capacities (3866 ± 263 N) (p < 0.05) among all the groups tested. No statistically significant differences were found in the load-bearing capacities between crowns made with different composite-core materials (p > 0.05). everX Flow exhibited the highest FT (2.8 MPa m1/2) and Z500 presented the highest FS values (197 MPa) (p < 0.05) among tested composites. With regard to the failure-mode analysis, crowns that had a fiber-reinforced core material of everX Flow revealed delaminating of surface conventional composite from the substructure layer. While in crowns that had a core material of SDR Flow+ or having only conventional composites with no fiber reinforcement, showed a crushing fracture pattern. ConclusionRestorations combining a fiber-reinforced composite core and a surface layer of conventional composite, displayed promising performance related to fracture-behavior.

Clinical Evaluation of Fiber-Reinforced Composite Restorations in Posterior Teeth - Results of 2.5 Year Follow-up.

Objectives:The aim of this study was to evaluate the clinical performance of posterior composite restorations reinforced by bulk base of short-fiber composite (everX Posterior, GC Corporation).Methods:Thirty-six short fiber-reinforced composite restorations were placed in premolar and molar teeth of 33 patients. Eight of the teeth were vital and 28 were non-vital. Average follow up time of the restorations was 30.6 months (2.5 years), ranging from 16.2 to 51.3 months (1.3 - 4.3 years).Results:One restoration failed during the follow-up period due to secondary caries, at time point 39.5 months. Three fillings had minor fractures during the follow-up. The overall survival rate of the restorations was 97.2% and success rate (no maintenance needed) was 88.9%, respectively.Conclusion:Posterior composite restorations with a bulk base of short-fiber composite showed good clinical performance in the short term evaluation.

Short fiber-reinforced composite restorations: A review of the current literature.

A newly-recommended method for restoring large cavities is the biomimetic approach of using short fiber-reinforced composite (SFRC) as dentine-replacing material. The aim of the current review was to present an overview of SFRC and to give the clinician a detailed understanding of this new material and treatment strategy based on available-literature review. A thorough literature search was done up to December 2017. The range of relevant publications was surveyed using PubMed and Google Scholar. From the search results, articles related to our search terms were only considered. The search terms used were "short fiber-reinforced composite", "everX posterior", and "fiber-reinforced composite restorations". Of the assessed articles selected (N=70), most were laboratory-based research with various test specimen designs prepared according to the ISO standard or with extracted teeth; only four articles were clinical reports. A common finding was that by combining the SFRC as a bulk base with conventional composite, the load-bearing capacity and failure mode of the material combination were improved, as compared to plain conventional composite restoration. In the reviewed studies, the biomimetic restoration technique of using SFRC showed promising characteristics, and therefore, might be recommended as an alternative treatment option for large cavities.

Comparative Evaluation of the Fracture Resistance of Two Different Fiber-reinforced Composite Restorations with Particulate Filler Composite Restorations.

Uncomplicated crown fractures are the most common form of traumatic dental injuries (TDIs) in children affecting their personal and social well-being.AimTo evaluate the fracture resistance of fractured incisors restored with particulate filler composites, glass fiber-reinforced composites, and Polyethylene fiber-reinforced composite restorations.Materials and methodsStandardized incisal and mesio-incisal fractures with chamfer preparation were prepared on human maxillary central incisors. Test samples were restored using particulate filler composites (Filtek Z 250), glass fiber-reinforced composites (Fiber-Splint) and polyethylene-reinforced composites (Ribbond). Static load was applied to the test samples using Universal testing machine at a cross-head speed of 1 mm/min. Data were tabulated and analyzed using analysis of variance (ANOVA) (p = 0.05).ResultsDescriptive statistics of mean [standard deviation (SD)] peak failure load in incisal restorations for particular filler composite, glass fiber-reinforced composites, and polyethylene fiber-reinforced composites were 196.00 (± 67.46), 186.28 (± 66.44), and 246.71 (± 24.52) respectively, whereas for mesio-incisal restorations, mean (SD) peak failure loads were 169.28 (± 33.53), 218.57 (± 74.41), and 225.71 (± 57.52) respectively.ConclusionPolyethylene-reinforced composites showed an improved load-bearing capacity in incisal and mesio-incisal restorations when compared with particulate filler composites and glass fiber-reinforced composites.How to cite this article: Patnana AK, Rao VVN, Chandrabhatla SK, Rajasekhar VR. Comparative Evaluation of the Fracture Resistance of Two Different Fiber-reinforced Composite Restorations with Particulate Filler Composite Restorations. Int J Clin Pediatr Dent 2018;11(4):277-282.

Fracture behavior of single-structure fiber-reinforced composite restorations

Objective: The applications of single-structure fiber-reinforced composite (FRC) in restorative dentistry have not been well reported. This study aimed to clarify the static mechanical properties of anterior crown restorations prepared using two types of single-structure FRC.Materials and methods: An experimental crown restoration was designed for an upper anterior incisor. The restorations were made from IPS Empress CAD for CEREC (Emp), IPS e.max® CAD (eMx), experimental single-structure all-FRC (a-FRC), Filtek™ Supreme XTE (XTE), and commercially available single-structure short-FRC (everX Posterior™) (n = 8 for each material) (s-FRC). The a-FRC restorations were prepared from an experimental FRC blank using a computer-aided design and manufacturing (CAD/CAM) device. A fracture test was performed to assess the fracture load, toughness, and failure mode. The fracture loads were vertically applied on the restorations. The surface micromorphology of the FRC restorations was observed by scanning electron microscopy (SEM). The data were analyzed by analysis of variance (p = .05) followed by Tukey's test.Results: s-FRC showed the highest mean fracture load (1145.0 ± 89.6 N) and toughness (26.2 ± 5.8 Ncm) among all the groups tested. With regard to the micromorphology of the prosthetic surface, local crushing of the fiberglass was observed in s-FRC, whereas chopped fiberglass was observed in a-FRC.Conclusions: The restorations made of short-FRC showed a higher load-bearing capacity than those made of the experimental all-FRC blanks for CAD/CAM. The brittle-like fractures were exhibited in the recent dental esthetic materials, while local crushing fractures were shown for single-structure FRC restorations.

Effect of novel restoration techniques on the fracture resistance of teeth treated endodontically: An in vitro study.

The aim was to evaluate the effects of fiber-reinforced composite restorations and a bulk-fill resin composite on the fracture strength of mandibular premolars treated endodontically. Standard mesio-occluso-distal (MOD) cavities were prepared in 48 mandibular premolars. Following root canal treatment, teeth were assigned to four groups: Group 1, nano-hybrid resin composite; Group 2, polyethylene woven fiber plus nano-hybrid resin composite; Group 3, short fiber-reinforced resin composite plus nano-hybrid resin composite; and Group 4, bulk-fill resin composite plus nano-hybrid resin composite. Then, the teeth were subjected to the fracture toughness test. The data were analyzed statistically using one-way ANOVA, followed by Tukey's post-hoc test. The fiber-reinforced groups had better results than the nano-hybrid and bulk-fill composites (p<0.05), while the bulk-fill and nano-hybrid composite restorations gave similar results (p>0.05). Fiber-reinforcement improved the fracture strength of teeth with large MOD cavities treated endodontically. Bulk-fill composites can be used reliably as well as nano-hybrid composites.

Comparison of two different restoration materials and two different implant designs of implant-supported fixed cantilevered prostheses: A 3D finite element analysis

Abstract Purpose: A key factor for the success or failure of a dental implant is the manner of stresses transferred to the surrounding bone. Parallel to this situation, cantilever extensions where it is not possible to place another implant, would cause greater stress and it should be avoided if possible. Manufacturers and clinicians try to develop new implant designs and superstructure materials to reduce the stresses around the implant and supporting bone tissue. This study analyzed the influence of superstructure materials and implant designs on stress distribution around dental implants supporting cantilever restoration under loading conditions. Materials and Methods: Three-dimensional finite element models of a 3-unit cantilever bridge were subjected to 150 N occlusal load to evaluate two different superstructure materials (conventional metal ceramic, fiber reinforced composite) and two different implant designs, cylinder type (Institut Straumann AG, Waldenburg, Switzerland) and cylinder type with micro threads around implant neck (Astra Tech AB, Mölndal, Sweden). To evaluate the distribution of stresses within the bone surrounding the implants, 3-dimensional finite element analysis was conducted using four mathematical models of unilateral 3-unit cantilever fixed partial dentures supported by two implants. Results: The stress distribution patterns and stress values were similar and stress concentrations were similar in both restoration materials. The highest stress concentrations were around the adjacent ITI implant, which supports the conventional metal porcelain restoration. Conclusions: Although, there was no significant difference in stress distribution between fiber reinforced composite (FRC) and conventional metal porcelain, stress values were lower in FRC restorations. The Astra-Tech micro-thread design reduced the stress that was distributed throughout the implant body, but it should be noted that the peak stress was still present on the implant neck.

Directly fabricated inlay-retained glass- and polyethylene fiber-reinforced composite fixed dental prostheses in posterior single missing teeth: a short-term clinical observation.

To evaluate the clinical usefulness of directly fabricated glass and polyethylene resin-bonded fiberreinforced composite (FRC) inlay-retained fixed dental prostheses (FDPs) in posterior single missing teeth over a short period of time. Fourteen inlay-retained FRC FDPs with tub-shaped or box-shaped retainers were directly constructed in patients of both genders. A baseline examination was performed and the patients were examined regularly at 6-month intervals. The sulcus bleeding index, Silness-Löe plaque index, and probing depths of the abutments were checked regularly. Modified US Public Health Service (USPHS) parameters were used to compare the restorations at baseline and final examination. The Kaplan-Meier survival estimation method was performed to detect the overall survival rates and mean survival times of the restorations at the end of the follow-up. The length of the clinical observation was between 16 and 40 months for the FDPs still functioning after the end of the follow-up. No partial or total debonding of the prostheses or fracture of the frameworks was detected. Four veneering composite fractures at the veneer layer/fiber framework interface occurred in the pontic elements of 2 glass FRC FDPs and 2 polyethylene FRC FDPs after 6 and 10 months, and 20 and 22 months, respectively. Periodontal evaluation revealed clinically acceptable results, as did the USPHS evaluation. The overall survival curves of Kaplan-Meier at the end of the follow-up illustrated a 71% survival rate for the both glass and polyethylene FRC FDPs with mean survival times of 27 and 35 months, respectively. This study reported a mean period of service of 19 and 31 months for directly fabricated inlayretained glass and polyethylene FRC FDPs, respectively, with a 71% survival rate for the two framework constructions. Within the limitations of the study, these results can only be considered as preliminary. However, because of the lack of clinical data available for directly fabricated inlay-retained FRC FDPs, the results of this clinical observation may contribute to the still-evolving clinical knowledge of the FRC restorations.

Relationship of Margin Design for Fiber-Reinforced Composite Crowns to Compressive Fracture Resistance

Fiber-reinforced composite restorations provide excellent esthetics; however, little is known regarding the influence of margin design on marginal fit and fracture resistance for this type of crown. This study evaluated the effect of variations in tooth-preparation design on the marginal fit and compressive fracture resistance of fiber-reinforced composite crowns. Three metal dies with a total convergence of 5° and different margin designs (0.5-mm light chamfer, 1.0-mm deep chamfer, and 1.0-mm shoulder) were prepared. Sixty standardized crowns (FibreKor) were made on duplicated base metal alloy dies (n = 20 for each margin design). Marginal fit was stereoscopically evaluated by measuring the distances between each of the four pairs of indentations on the crowns and on the dies. The specimens were then subjected to a compressive fracture-loading test using a universal testing machine. The data were analyzed with one-way analysis of variance (ANOVA) followed by Ryan-Einot-Gabriel-Welsch multiple-range test (α = 0.05). Analysis of marginal fit and fracture resistance disclosed a statistically significant difference for tooth-preparation design (p < 0.001). The marginal adaptation of preparations with the 0.5-mm light chamfer (66.2 μm) and 1.0-mm deep chamfer (69.7 μm) was significantly better than preparations with a shoulder finish line (92.8 μm) (p < 0.001). The fracture strength of the preparations with the 0.5-mm light chamfer (15.8 MPa) and 1.0-mm deep chamfer (15.1 MPa) was significantly greater than those of the preparations with the 1.0-mm shoulder (13.7 MPa) (p < 0.001). Marginal fit of fiber-reinforced crowns was adversely affected by tooth-preparation design. The marginal gaps were greater for the shoulder margin specimens than in the light or deep chamfer margin specimens; however, the fracture strength of the chamfer margin specimens was greater than that of the shoulder margin specimens.

In Vitro Repair of Fractured Fiber-Reinforced Cusp-Replacing Composite Restorations

Objective. To assess fracture resistance and failure mode of repaired fiber-reinforced composite (FRC) cusp-replacing restorations. Methods. Sixteen extracted human premolars with fractured cusp-replacing woven (Group (A)) or unidirectional (Group (B)) FRC restorations from a previous loading experiment were repaired with resin composite and loaded to fracture. Results. Differences in fracture loads between groups were not statistically significant (P = 0.34). Fracture loads of repaired specimens were significantly lower than those of original specimens (P = 0.02 for Group (A) and P < 0.001 for Group (B)). Majority of specimens showed failure along the repaired surface. In Group (B) 89% of specimens showed intact tooth substrate after restoration fracture, while this was 28% in Group (A) (P = 0.04). Conclusion. Fractured cusp-replacing FRC restorations that are repaired with resin composite show about half of fracture resistance of original restorations. Mode of failure with a base of unidirectional fibers is predominantly adhesive.

Direct Fiber-reinforced Composite Restoration in an Endodontically-treated Molar: A Three-year Case Report

The reconstruction of structurally compromised non-vital posterior teeth may represent one of the most challenging adhesive-based restorative procedures. Several factors may influence the longevity of direct fiber-reinforced resin composite restorations: endodontic procedures prior to post cementation, dentin and/or post surface treatments, selection of the appropriate post design and architecture, resin composite polymerization and layering techniques. Thus, different specialties, such as endodontics and restorative dentistry, should work as a team to improve the longevity of restorations. This article presents three-year clinical results following reconstruction of a severely damaged endodontically-treated molar using direct fiber reinforced resin composite systems.

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.

Fracture resistance of fiber-reinforced composite restorations with different framework design

Objectives. Veneer fracture and bond deficiency between framework and veneer are typical failures of fiber-reinforced inlay fixed partial dentures (FPD). An eccentric load point on the pontic was used in this study to investigate the fracture resistance of FPDs with different framework designs. As null hypothesis, it was assumed that fracture resistance was not influenced by the fiber framework supporting the veneer. Methods. Four groups of Vectris/Adoro FPDs (4×n=10 each) were manufactured. Beams (25 mm length) of Vectris Pontic (parallel aligned) with (a) rectangular (3×3) sectional view and (b) circular sectional view (⊘ 3 mm) were directly veneered using Adoro. (c) Circular beams like “b” were modified, i.e. those on the upper side were coated with two layers of the cross-sectioned fiber mat Vectris frame. (d) Vectris Pontic fibers were “anatomically” placed in the pontic area and wrapped using Vectris Frame. The frameworks were constructed in a vacuum/pressure process. All FPDs were mounted in a restrained-end apparatus and thermally cycled and mechanically loaded (TCML: 6000×5°C/55°C; 1.2×106×50 N, 1.66 Hz). After TCML, the FPDs were loaded to fracture. Results. All FPDs surpassed TCML, with no visible damage to the veneer or framework. Without transversal enlargement of the framework, additional cross-sectioned fiber mats alone did not improve resistance to fracture (a: 573±158 N (mean, standard deviation given); b: 737±66 N; c: 694±93 N; d: 902±149 N). Fracture lines occurred only in the veneer; the fiber frameworks were never affected. Conclusions. Anatomical enlargement of the fiber framework at the pontic area (height, width) to support the veneer material improves the fracture resistance of fiber-reinforced FPDs.