Evaluation of the flexural strength of carbon fiber-, quartz fiber-, and glass fiber-based posts

This study investigated the flexural strength of eight fiber posts (one carbon fiber, one carbon/quartz fiber, one opaque quartz fiber, two translucent quartz fiber, and three glass fiber posts). Eighty fiber posts were used and divided into eight groups (n = 10): G1: C-POST (Bisco); G2: ÆSTHETI-POST (Bisco); G3: ÆSTHETI-PLUS (Bisco); G4: LIGHT-POST (Bisco); G5: D.T. LIGHT-POST (Bisco); G6: PARAPOST WHITE (Coltene); G7: FIBERKOR (Pentron); G8: REFORPOST (Angelus). All of the samples were tested using the three-point bending test. The averages obtained were submitted to the ANOVA and to Tukey's test (p < 0.05). The mean values (MPa) of the groups ÆSTHETI-POST - carbon/ quartz fiber post (Bisco) and ÆSTHETI-PLUS - quartz fiber post (Bisco) were statistically similar and higher than the mean values of the other groups. The mean values of the groups C-POST - carbon fiber post (Bisco), LIGHT-POST - translucent quartz fiber post (Bisco), D.T. LIGHT-POST - double tapered translucent quartz fiber post (Bisco), PARAPOST WHITE - glass fiber post (Coltene) and FIBREKOR - glass fiber post (Pentron) were similar and higher than the group REFORPOST - glass fiber post (Angelus). Copyright © 2005 by the American Association of Endodontists.

Restoration of severely decayed primary incisors using indirect composite resin restoration technique

Caries of primary incisors is a common problem in paediatric dentistry in some countries. The restoration of primary incisors which have been severely damaged by early childhood caries or trauma is also a difficult challenge for clinicians. This case report describes an indirect technique for the restoration of primary anterior teeth using composite resin reinforced with a fibreglass post. Over a one-year period, the crowns have demonstrated good retention and aesthetic results. The restorations were provided in two short chair-side sections, with satisfactory patient cooperation. © 2005 BSPD and IAPD.

The effect of adhesive systems on the pullout strength of a fiberglass-reinforced composite post system in bovine teeth

Purpose: To evaluate the pullout strength of a glass fiber-reinforced composite post (glass FRC) cemented with three different adhesive systems and one resin cement. The null hypothesis was that pullout strengths yielded by the adhesive systems are similar. Materials and Methods: Thirty bovine teeth were selected. The size of the specimens was standardized at 16 mm by sectioning off the coronal portion and part of the root. The specimens were divided into three groups, according to the adhesive system, which were applied following the manufacturers' instructions: G1, ScotchBond Multi-Purpose Plus; G2, Single Bond; G3, Tyrian SPE/One-Step Plus. The glass FRCs (Reforpost) were etched with 37% H3PO4 for 1 min and silanized (Porcelain Primer). Thereafter, they were cemented with the dual resin cement En-Force. The specimens were stored for 24 h, attached to an adapted device, and submitted to the pullout test in a universal testing machine (1 mm/min). The data were submitted to the one-way ANOVA and Tukey's test (α = 0.05). Results: G1 (30.2 ± 5.8 Kgf) displayed the highest pullout strength (p < 0.001) when compared to G2 (18.6 ± 5.8 Kgf) and G3 (14.3 ± 5.8 Kgf), which were statistically similar. Analysis of the specimens revealed that all failures occurred between the adhesive system and the root dentin (pullout of the post cement), regardless of group. Conclusion: The multiple-bottle, total-etch adhesive system provided higher pullout strength of the glass FRC when compared to the single-bottle, total-etch, and single-step self-etching adhesive systems. The null hypothesis was rejected (p < 0.001).

Influence of brush type as a carrier of adhesive solutions and paper points as an adhesive-excess remover on the resin bond to root dentin

Purpose: To evaluate the influence of the brush type as a earner of priming adhesive solutions and the use of paper points as a remover of the excess of these solutions on the push-out bond strength of resin cement to bovine root dentin. The null hypotheses were that brush type and the use of paper points do not affect the bond strength. Materials and Methods: The canals of 80 single-root bovine roots (16 mm in length) were prepared at 12 mm using the preparation drill (FRC Postec Plus, Ivoclar). Half of each root was embedded in acrylic resin and the specimens were divided into 8 groups, considering the factors brush type (4 levels) and paper point (2 levels) (n = 10): Gr 1: small microbrush (Cavi-Tip, SDI); Gr 2: Microbrush (Dentsply); Gr 3: Endobrush (Bisco); Gr 4: conventional brush (Bisco); Gr 5: Cavi-Tip (SDI) + paper points; Gr 6: Microbrush (Dentsply) + paper points; Gr 7: Endobrush (Bisco) + paper points; Gr 8: conventional brush (Bisco) + paper points. The root dentin was treated with a multistep total-etch adhesive system (All Bond 2). The adhesive system was applied using each microbrush, with and without using paper points. One fiber post was molded with addition silicon and 80 posts were made of resin cement (Duolink), The resin posts were luted (Duolink resin cement), and the specimens were stored for 24 h in water at 37°C. Each specimen was cut into 4 disk-shaped samples (1.8 mm in thickness), which were submitted to the push-out test. Results: The brush type (p < 0.0001) (small microbrush > microbrush = endobrush = conventional brush) and the use of paper points (p = 0.0001) (with > without) influenced the bond strength significantly (two-way ANOVA). The null hypotheses were rejected. Conclusion: The smallest brush (Cavi-Tip) and the use of paper points significantly improved the resin bond to bovine root dentin.

Fatigue resistance of bovine teeth restored with resin-bonded fiber posts: Effect of post surface conditioning

This study evaluated the effect of post surface conditioning on the fatigue resistance of bovine teeth restored with resin-bonded fiber-reinforced composite (FRC). Root canals of 20 single-rooted bovine teeth (16 mm long) were prepared to 12 mm using a preparation drill of a double-tapered fiber post system. Using acrylic resin, each specimen was embedded (up to 3.0 mm from the cervical part of the specimen) in a PVC cylinder and allocated into one of two groups (n = 10) based on the post surface conditioning method: acid etching plus silanization or tribochemical silica coating (30 μm SiOx + silanization). The root canal dentin was etched (H2PO3 for 30 seconds), rinsed, and dried. A multi-step adhesive system was applied to the root dentin and the fiber posts were cemented with resin cement. The specimens were submitted to one million fatigue cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture. All of the specimens were resistant to fatigue. No fracture of the root or the post and no loss of retention of the post were observed. The methodology and the results of this study indicate that tribochemical silica coating and acid etching performed equally well when dynamic mechanical loading was used.

Comparison of resin push-out strength to root dentin of bovine- and human-teeth

Aim : To compare the push-out strength of bovine- and human-root dentin and, thus, evaluate the suitability of bovine-root dentin to substitute human-root dentin for bond strength testing. Materials and Methods : Ten single-rooted human-teeth and ten bovine incisors were prepared using a #3 bur of a fiber post system (12 mm long). The posts were duplicated with resin cement (Duolink). The root canals were treated with All Bond 2 adhesive system and the resin posts were cemented using Duolink. The specimens were cut perpendicular to their long axis, yielding disc-specimens with 1.5 mm thickness, which were submitted to a push-out test (1 mm/min). Ten bond strength values per group (n = 10) were used for statistical analysis (Student t test, a =.05). Results : Statistically significant differences were found for the bond strength values between bovine- (4.1 1.3 MPa) and human-root dentin (8.6 5.7 MPa) (P =.0001). Conclusion : The push-out strengths of bovine- and human-root dentin were statistically different.

Functional and esthetic rehabilitation with In-Ceram alumina and zirconia system: A multidisciplinary approach

The development of all-ceramic systems following metalceramics restorations allowed simulation of natural dentition due to favorable esthetics and resistance. In-Ceram is an alternative when esthetics is primordial as well as resistance required in rehabilitation. However, an ideal smile is associated to not only shape, color, texture and translucency but also harmony with gingival tissue. So, the aim of this study is to report a clinical case based on periodontal and fixed partial dentures principles to perform periodontal plastic surgery followed by esthetic rehabilitation. A female patient, 40-year-old, presented complaint about dental esthetics. After clinical and radiographic exams, metal-ceramics crowns (teeth 11, 12, 13, 21, 22 and 23) were considered unsatisfactory due to marginal leakage, color change in gingival tissue associated to metallic margin, and gummy smile. So, a crown lengthening surgery of anterior teeth was performed followed by rehabilitation of superior teeth with In-Ceram single crowns. Clinical significance: The interaction between periodontics and fixed prosthodontic area is the key of an adequated treatment planning which involves gingival smile to provide function and an esthetic condition in association with an esthetic, resistant and predictable material.

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: Eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts-FRC and cast post and core-CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom # 2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45 degrees, 37 degrees C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45 degrees device with 1 mm/min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario.

Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of adhesive system on quartz fiber post dislocation resistance in endodontically treated teeth

Aim: To evaluate the dislocation resistance of the quartz fiber post/cement/dentin interface after different adhesion strategies. Methods: Forty bovine lower central incisors were selected and prepared with K-files using the step-back technique, and irrigated with 3 mL of distilled water preceding the use of each instrument. Prepared teeth were stored at 37ºC and 100% humidity for 7 days. The roots were prepared and randomized into 4 groups. The quartz fiber post was cemented with an adhesion strategy according to the following groups: GBisCem- BISCEM; GOneStep±C&B- One Step ± C&B; GAllBond±C&B- AllBond3 ± C&B; GAllBondSE±C&B- AllBondSE ±C&B with a quartz fiber post. Cross-sectional root slices of 0.7 mm were produced and stored for 24 h at 37° C before being submitted to push-out bond strength. Results: The mean and standard deviation values of dislocation resistance were GBisCem: 1.12 (± 0.23) MPa, GOneStep±C&B: 0.81 (± 0.31) MPa, GAllBond±C&B: 0.98 (± 0.14) MPa, and GAllBondSE±C&B: 1.57 (± 0.04) MPa. GAllBondSE±C&B showed significantly higher values of dislocation resistance than the other groups. Conclusions: Based on this study design, it may be concluded that adhesion strategies showed different results of quartz post dislocation resistance. Simplified adhesive system with sodium benzene sulphinate incorporation provided superior dislocation resistance.

Fracture strength of flared bovine roots restored with different intraradicular posts

Objective: The aim of this study was to evaluate the fracture strength and failure mode of flared bovine roots restored with different intraradicular posts. Material and Methods: Fifty bovine incisors with similar dimensions were selected and their roots were flared until 1.0 mm of dentin wall remained. Next, the roots were allocated into five groups (n=10): GI-cast metal post-and-core; GII-fiber posts plus accessory fiber posts; GIII-direct anatomic post; GIV-indirect anatomic post and GV-control (specimens without intraradicular post). A polyether impression material was used to simulate the periodontal ligament. After periodontal ligament simulation, the specimens were subjected to a compressive load at a crosshead speed of 0.5 mm/min in a servo-hydraulic testing machine (MTS 810) applied at 135 to the long axis of the tooth until failure. The data (N) were subjected to ANOVA and Tukey's post-hoc test (alpha=0.05). Results: GI and GIV presented higher fracture strength (p<0.05) than GII. GIII presented intermediate values without statistically significant differences (p>0.05) from GI, GII and GIV. Control specimens (GV) produced the lowest fracture strength mean values (p<0.05). Despite obtaining the highest mean value, GI presented 100% of unfavorable failures. GII presented 20% of unfavorable failures. GIII, GIV and GV presented only favorable failures. Conclusions: Although further in vitro and in vivo studies are necessary, the results of this study showed that the use of direct and indirect anatomic posts in flared roots could be an alternative to cast metal post-and-core.

Resistance to compression of weakened roots subjected to different root reconstruction protocols

Objective: This study evaluated, in vitro, the fracture resistance of human non-vital teeth restored with different reconstruction protocols. Material and methods: Forty human anterior roots of similar shape and dimensions were assigned to four groups (n=10), according to the root reconstruction protocol: Group I (control): non-weakened roots with glass fiber post; Group II: roots with composite resin by incremental technique and glass fiber post; Group III: roots with accessory glass fiber posts and glass fiber post; and Group IV: roots with anatomic glass fiber post technique. Following post cementation and core reconstruction, the roots were embedded in chemically activated acrylic resin and submitted to fracture resistance testing, with a compressive load at an angle of 45 degrees in relation to the long axis of the root at a speed of 0.5 mm/min until fracture. All data were statistically analyzed with bilateral Dunnett's test (alpha=0.05). Results: Group I presented higher mean values of fracture resistance when compared with the three experimental groups, which, in turn, presented similar resistance to fracture among each other. None of the techniques of root reconstruction with intraradicular posts improved root strength, and the incremental technique was suggested as being the most recommendable, since the type of fracture that occurred allowed the remaining dental structure to be repaired. Conclusion: The results of this in vitro study suggest that the healthy remaining radicular dentin is more important to increase fracture resistance than the root reconstruction protocol.

The influence of ultrasound on the retention of cast posts cemented with different agents

Aim: The aim of this study was to evaluate the influence of ultrasound during the removal of posts cemented with either zinc phosphate cement, glass ionomer cement or resin cement. Methodology: Eighty-four single-rooted teeth were prepared and after cementation of cast posts, they were randomly divided into six groups of 14. Groups 1, 2 and 3 did not receive ultrasonic vibration, whilst groups 4, 5 and 6 received ultrasonic vibration for 10 min. The force necessary for post removal was determined using a universal testing machine. Results were statistically analysed using ANOVA and Tukey tests (5%). Results: The application of ultrasonic vibration reduced the retention provided by zinc phosphate and glass ionomer cements by 39% and 33%, respectively. Conclusions: A statistically significant reduction in the force necessary to remove posts cemented with zinc phosphate and glass ionomer cements occurred following application of ultrasound. The application of ultrasonic vibration did not influence the retention of cast posts cemented with resin cement.

Effect of silica coating on flexural strength of fiber posts

Purpose: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. Materials and Methods: Six experimental groups of FRC posts (n = 10 per group) were tested, either as received from the manufacturer or after chairside silica coating (30-μm CoJet-Sand). Results: There was no significant difference in the flexural strength of nonconditioned (504 to 525 MPa) and silica-coated (514 to 565 MPa) specimens (P > .05) (analysis of variance). The type of post did have a significant effect on flexural strength (P < .05). Conclusion: Chairside silica coating did not affect the flexural strength of both carbon and quartz FRC posts.