Statement of problem: Debonding is the most frequent failure encountered with translucent fiber posts and usually occurs along the post space dentin-adhesive interface.
Purpose: The purpose of this study was to evaluate the effect of different dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and root dentin in different regions of the post space.
Methods: Forty maxillary canines with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were endodontically treated. Following post space preparation, the roots were divided into 4 groups of 10 specimens each, and the post spaces were treated with 1 of 4 different dentin bonding agents: light-polymerized, single-bottle bonding agent Excite (Group EX); dual-polymerized, single-bottle bonding agent Excite DSC (Group EX-DSC); self-etching primer Clearfil Liner Bond 2V with a light-polymerized bonding agent, Bond A (Group CL-LC); or self-etching primer Clearfil Liner Bond 2V with a dual-polymerized bonding agent, Bond A+B (Group CL-DC). Translucent fiber posts (D.T. Light-Post), 2.2 mm in diameter, were luted (Panavia F) in each specimen after respective dentin bonding procedures. The roots were cut into 3-mm-thick sections, perpendicular to the long-axis in cervical, middle, and apical post space dentin. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and bond strength values (MPa) were calculated by dividing the force at which bond failure occurred by the bonded area of the post. The data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (alpha=.05). Dentin adhesive bonding mechanisms in different regions of the post spaces were evaluated with a scanning electron microscope.
Results: The highest mean bond strength values were obtained for Group CL-LC (18.3 +/- 4.1 MPa). The dual-polymerized bonding agent resulted in significantly lower bond strength (P<.001) in combination with self-etching primer (Group CL-DC) (13.2 +/- 2.5 MPa). The light-polymerized and dual-polymerized single-bottle bonding agents provided similar bond strengths (12.7 +/- 5.0 for EX; 13.5 +/- 5.3 for EX-DSC). The regional bond strength values of single-bottle bonding agents were reduced significantly in apical post space dentin (P<.001). Self-etching primers did not demonstrate regional differences in post space dentin bonding and dense resin tags were apparent.
Conclusions: Data suggests that the self-etching primer system used in this study was unaffected by the morphological variations in the post space dentin compared to the single-bottle bonding agents. Dual polymerization did not improve the bond strength values of the bonding agents tested.

Objectives: To evaluate the regional microtensile bond strengths of various fiber posts to root canal dentin luted with dual-cure resin composite.
Methods: Twelve extracted human premolars were decoronated and post spaces prepared to a depth of 8 mm. The root canal dentin was treated with Clearfil SE Bond and light-cured for 20 s. Three of the following fiber posts: Snowlight, FiberKor, D.T. Light-Post, and GC Fiber Post were cut to a length of 12 mm and surface-treated with a mixture of Porcelain Bond Activator and Photobond. The posts were then luted into the prepared post spaces with Clearfil DC Core Automix and light cured for 60s. After 24 hrs water storage, each specimen was serially sliced into 8, 0.6 x 0.6 mm-thick beams for the microtensile bond strength (μTBS) test. Failure modes were observed under SEM. Bond strength data were divided into coronal and apical regions and analyzed using two-way ANOVA and Tukey's HSD (α = 0.05).
Results: Mean(SD) of μTBS in MPa were as follows (n=12). The same superscripts within each row and the brackets demonstrate no significant differences. FiberKor and D.T. Light-Post specimens mostly failed at the post/resin composite interface, whereas Snowlight and GC Post cohesively failed within the post.
Conclusion: FiberKor post exhibited the highest bond strength among the four tested posts. No regional differences in μTBS were found for all posts. Failures occurred either at the post/resin composite interface or within the post and were dependent upon the post system.

Fiber posts are commonly used to restore endodontically treated teeth prepared for fixed partial dentures. Their mechanical properties and the use of adhesive cements seem to allow higher survival rates when compared to traditional cast or metal posts. The aim of this study was to compare the fatigue resistance of five different types of fiber posts. Fifty sound incisors, bicuspids and canines have been selected and endodontically treated. The crown was removed and they were randomly divided into five groups. Each group received 10 fiber posts inserted 9mm into the root. The posts were cemented using the dentin adhesive and the cement suggested by the manufacturer: 1) Carbon fiber (Composipost RTD/ Bisco C-POST); ALL-BOND 2 / C&B Cement (Bisco), 2) Quartz fiber post AesthetiPost (RTD / Bisco); ALL-BOND 2 / C&B Cement (Bisco), 3) Quartz fiber LIGHT-POST (RTD / Bisco); ONE-STEP (Bisco) and DUO-LINK cement (Bisco), 4) Glass fiber FIBER-KOR (Jeneric Pentron) Post; BOND-1 (Jeneric Pentron) and Cement-It! (Jeneric Pentron) , 5) Quartz fiber D. T. LIGHT-POST (RTD / Bisco); ONE-STEP (Bisco) and DUO-LINK cement (Bisco). Post diameter was 1.4mm for groups 1 – 4 and 1.5mm for group 5. Each group was subdivided into a control group and an experimental one. Specimens from the experimental groups underwent 2 million 8Hz frequency load cycles in distilled water at 370C. During each cycle, the load ranged from 3 to 21 Newtons and was applied directly one the post in 450 direction. The controls were stored in water at 270C. After the tests, all the specimens were imbedded in epoxy resin and sectioned transversely, obtaining 1mm thick sections. The sections were observed under the stereomicroscope and the post/cement (PC) and (CD) cement/dentin interfaces were evaluated using an ordinal scale.. One post (Aestheti-Post) fractured after 1.5 million cycles. LIGHT-POST and D. T. LIGHT-POST gave the better results (P<0.009) at both interfaces. The PC interface appeared significantly stronger (P<0.05) than CD when tested with Kruskal-Wallis test. Significant differences (P<0.05) were found between controls and experimentals in groups 4 & 5. It was concluded that Quartz fiber posts are very resistant to fatigue stress and the adhesion at CD interface could be improved.

Objectives: The aim of this study is to evaluate the effect of the endodontic treatment on the fatigue resistance of endodontic post adhesive interfaces.
Methods: FIFTY single-rooted human teeth have been severed at the CEJ and randomly assigned to 5 groups receiving different endodontic treatments as follows: 1) distilled water + gutta percha (control); 2) NaOCl 5% + gutta percha + Pulp Canal Sealer EWT (Kerr); 3) NaOCl 5% + gutta percha + TopSeal (Dentsply-Maillefer); 4) NaOCl 5% and EDTA 10% (alternatively) + gutta percha + Pulp Canal Sealer EWT; 5) NaOCl 5% and EDTA 10% (alternatively) + gutta percha + TopSeal. Subsequently, #2 DT LIGHT-POST (RTD/Bisco) quartz fiber posts have been placed in the root canal using ALL-BOND 2 adhesive (Bisco) and Bis-Fil 2B composite (Bisco). Five specimens from each group have been subjected to 2,000,000 fatigue cycles ranging from 0 to 37.5N at 8Hz frequency and 370C water irrigation, whereas the remaining specimens were stored in distilled water at room temp. After the fatigue cycles, all of the specimens were severed obtaining 4 sections from each tooth, which were then evaluated with the push-out test at a constant speed of 1mm/min. Stereomicroscope and SEM observations were done to evaluate the interface failures.
Results: no statistically significant differences were observed between the 5 groups in both fatigue stressed (p=0.298) and water stored specimens (p=0.093). Also, the microscope analysis of interface failures showed that the post-cement interface is weaker than the cement-dentin one. The difference was significant with P=0.001.
Conclusions: the results suggest that the interface resistance is not influenced by the canal treatments adopted in this study. Probably the hard tissue removal necessary for post placement eliminated contaminated or altered dentin that may affect the bonding with the luting cement. High resistance of the cement-dentin interface strongly supports this last hypothesis.

Objective: To evaluate the effect of the activation mode of adhesive cementation on push-out bond strength of fiber-reinforced resin posts to root canal dentin.
Methods:Forty mandibular premolars were endodontically treated and randomly divided into 4 equal groups. In groups G-1, G-2, and G-3, Single Bond (3M Espe) was applied and light polymerized for 20 seconds; in group G-4, Scotchbond Multi-Purpose Plus (3M Espe) was used as an autopolymerized adhesive. The dual-cure resin cement Rely X ARC (3M Espe) was light polymerized in G-2 and G-3 but not in G-1 and G-4. The translucent post Light-Post (RTD/Bisco) was used in G-3 and the opaque post Aestheti-Plus (RTD/Bisco) in the other groups. The roots were sectioned in 3 parts (cervical, middle, apical); each slice was submitted to the push-out test at a crosshead speed of 0.5 mm/min. Data were analyzed by analysis of variance and Tukey test (a = .05).
Results: Light polymerization of both the adhesive and resin cement in G-2 led to significantly higher bond strength than in G-1, where only the adhesive was light polymerized. No difference was found between G-2 (opaque post) and G-3 (translucent post). The autopolymerized adhesive showed the highest bond strength in all root regions. The middle and apical post/root regions had similar bond strength, but it was significantly lower than that in the cervical region (P <.001).
Conclusion: Bond strength to root dentin varied as a function of the activation mode of post adhesive cementation and post/root regions

Objective: Clinical studies show a high failure incidence after years of service of endodontically treated premolars, when restored with post-core crowns, especially those with short posts or deficient ferrules. The reason for this can be a deterioration of the luting cement around the post by fatigue from functional loading. In particular, the anatomy of premolars may frequently be incompatible with the application of long endodontic posts. The aim of this study was to evaluate the influence of fatigue loading on the quality of the cement layer between posts with restricted lengths and the root canal wall in premolars. As the stiffness of posts may affect the outcome, post-and-core systems with varying post stiffness were selected.
Methods: Four types of post-and-core systems were selected for this study: three prefabricated post systems combined with a resin composite core material and one cast post and core. The three prefabricated posts were titanium posts (Tenax), quartz-fiber posts (Aestheti-Post), and quartz-coated-carbon-fiber posts (Aestheti-Plus). The post-and-core restorations were made on single-rooted, human, maxillary premolars from which the coronal sections were removed at the level of the proximal cementoenamel junction. Following endodontic treatment, a cast post and core (post length 6 mm) was prepared for each tooth individually (direct method) and cemented into the root canal with chemical cure Panavia 21 TC. The prefabricated posts were directly cemented in the root canal and then, after applying a dual-cure adhesive (Clearfil Photobond), built up with a core build-up composite (Clearfil Photocore). For each group (n = 8), half of the specimens were exposed to fatigue loading (10(6) load cycles) almost perpendicular to the axial axis (85 degrees), while the other half was used as the control. Three parallel, transverse root sections of 1.5-mm thickness, were cut from each specimen. These sections were examined by scanning electron microscopy (SEM) to evaluate the cement integrity, while the retention strength of the cemented post sections was determined with a push-out test.
Results: Fatigue loading did not cause separation of the buildups from the roots or affect the push-out strength. On a univariate level, only SEM evaluation showed significant differences between the types of post, fatigue loading, and between the levels of root sections. The cement integrity with the titanium post was significantly less than with the other three systems, which did not differ among themselves.
Conclusions: A composite core build-up material bonded to the dentin and supported by quartz-fiber posts or quartz-coated-carbon-fiber posts, cemented with adhesive cement may be a viable alternative for the conventional cast core.

Objective: to compare the in vitro retentive values of stainless steel, parallel sided posts to quartz fiber tapered posts for two different dowel lengths (5mm and 10mm).
Methods: Both post systems were cemented with a dual-cure adhesive resin cement. Single rooted extracted human teeth (n-40) were de-coronated and randomly divided into 4 groups of 10 samples each. Posts of 5 and 10mm in length were luted with the resin cement. Each sample was placed on a universal testing machine, and using a push-out method, a vertical load was applied at a crosshead speed of 2mm/min. The amount of force required to dislodge the post was recorded. The effect of post type and length was evaluated using a 2-way analysis of variance.
Results: A statistically significant main effect was found for post length (P<.001) with the 10mm posts of both post systems requiring greater force to dislodge than the 5mm posts. There was no interaction between post length and post type (P>.05).
Conclusion: It is concluded from this study that there is no statistical difference in retention between quartz fiber tapered posts (D. T. Light-Post) and stainless steel parallel-sided posts (ParaPost) when they are cemented with the same resin cement (P> .05). The study also concludes that adequate retentive values are achieved with both systems at the shorter, 5mm post length.

A maxillary central incisor with mild periodontitis and extensive loss of coronal tooth structure was endodontically treated and restored with a translucent quartz-fiber post and a composite core. Treatment was completed with the cementation of full-ceramic crowns on teeth 11 and 21. Informed consent was obtained from the patient. Due to the extent of the periodontal disease, tooth 11 was extracted two years later. With the patient's consent, the tooth was used for research. The tooth was sectioned at 11 levels perpendicularly to the long axis and investigated by means of optical microscopy and scanning electron microscope (SEM). The visual examination showed perfect adhesion between the various interfaces (restoration-dentin-post) at both the coronal and root levels. The adhesion between the post and dentin appeared to be free of gaps, and even where the composite cement showed a nonhomogeneous thickness, voids were not apparent. The tooth under examination allowed the authors to check the effectiveness of the adhesion and the integrity of the hybrid layer after exposure to the oral cavity for two years. The results of this investigation show that there were no gaps between the adhesive resin and dentin and no hydrolysis of the adhesive bond. This case suggests that it is possible to obtain good results in the short term from the cementation of quartz-fiber posts with composite resin cements.

Abstract/conclusions: The intent of this study was to determine pullout (shear) strength of carbon (Composipost) and stainless steel serrated posts from teeth. The tooth-posts groups were controls, thermal-cycled, load-cycled (load applied at either a 45o angle or along the long axis of the post), and thermal- and load-cycled. Human extracted third molars were embedded in denture acrylic. Post space was prepared and the posts were cemented with a resin cement according to manufacturer's instructions. The testing was in tension at a loading rate of 2 mm/min. The pullout (shear) strengths (MPa+SD) for the carbon posts were: controls 6.1+3.3; load-cycled 4.3+2.2; and thermal cycled 4.2+2.2. The thermal-cycled then load-cycled carbon posts all fractured during testing and were unable to be evaluated for shear strength. The pullout (shear) strengths (MPa+SD) for the stainless steel posts were: controls 6.6+2.9; load-cycled 7.1+3.2; thermal cycled 4.8+ 2.0; and thermal load-cycled 6.8+3.5. The statistical analysis indicated no significant difference in the pullout (shear) strength between any of the post groups tested. Two different operators then prepared specimens using carbon posts abraded with 50 micron alumina and non-abraded carbon posts. The alumina abrasion caused a decrease in the post bond strength with the alumina particles impinging on the carbon fibers resulting in their fracture. The significant difference between bond strengths was attributed to each operator's years of clinical experience.

Objectives: The retention of endodontic posts is believed to be a major factor in restoration survival. The purpose of this study was to evaluate the effect of post diameter on the bond strength of the fiber post D.T. Light Post using two different cements.
Methods: Sixty caries free human incisors were selected for standardized size and quality, endodontically treated and coronally reduced to the cemento-enamel junction. The specimens were randomly assigned to three experimental groups: (I): canal preparation with DT drill #1, insertion of DT Light Post #1, (II): canal preparation with DT drill #2, insertion of DT Light Post #2; (III) canal DT drill #3, insertion of DT Light Post #3. The fiber posts were cemented using either Calibra (subgroup C) or Panavia F (subgroup P). Retentive strength was measured 24 hours after cementation using a universal testing machine. Data were analyzed with SPSS 10.0.
Results:The following mean retentive strengths were evaluated:

		IC	IIC	IIIC	IP	IIP	IIIP
Mean value and standard deviation	in N	111.39 (+/-26.63)	127.63 (+/-29.67)	138.82 (+/-36.55)	127.58 (+/-28.56)	163.37 (+/-35.85)	200.98 (+/-28.66)
	in MPa (N/mm²)	10.91 (+/-2.61)	11.16 (+/-2.59)	10.14 (+/- 2.67)	12.51 (+/-2.80)	14.26 (+/-3.13)	14.68 (+/-2.09)

Statistic analysis showed that the post diameter did not affect the bond strengths the fiber posts of the D.T. Light Post system (p< 0.05, Tukey test). Posts cemented with Panavia showed higher bond strengths. In the case of size 3 posts this difference was significant (p< 0.05, Tukeyxs test).
Conclusions: The reconstruction of endodontically treated single rooted teeth with fiber posts showed acceptable retentive values for both cements used in this in vitro study. The post diameter did not affect the bond strengths of the D.T. Light Post system.

Objectives: This study aimed to evaluate the effect of mechanical cycling on the adhesive bond strengths at the root dentin/resin cement and resin cement/ceramic post interfaces.
Methods: Forty single rooted human teeth were transversally sectioned, with 16mm left for specimens. The canal preparation of 20 teeth was performed to receive a 12mm high ceramic post (Cosmo Post, Ivoclar) and another 20 teeth were prepared to receive a fiber reinforced post (FRC Postec, Ivoclar). The canals were treated with All-Bond 2 (Bisco) chemical polymerizable adhesive system and Duo-Link dual resin cement (Bisco). After that, ten specimens of each post were subjected to 2,000,000 mechanical cycles. A 1,6mm thick punch induced loads of 37,5Kg, at 45° angulation to the long axis of specimens and frequency of 8Hz, on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of teeth, generating slices of about 2mm (5 sections per teeth), which were subjected to the push-out test in a universal testing machine, EMIC, at 1mm/min crosshead speed. The mean bond strength was taken to each tooth and ten values per group (n=10) were subjected to statistical analysis.
Results: The Tukey test (5%) showed that the mean of the ceramic group subjected to the mechanical cycling (3,2577 ± 2,3345) was different to both ceramic control group (7,6819 ± 1,2628), Fiber reinforced group subjected to the mechanical cycling (6.901±1.930) and Fiber reinforced control group (6.823±2.214) . These three last groups did not differ statistically.
Conclusion: It was possible to conclude that the mechanical cycling of ceramic posts reduced the bond strengths at the root dentin/resin cement and resin cement/ceramic post interfaces.

Objectives: The retention of endodontic posts is believed to be a major factor in restoration survival. The aim of this study was to compare the retentive strength of fiber posts cemented with two different cements in combination with different pre-treatments.
Methods: Forty caries free human maxillary incisors were selected for standardized size and quality, endodontically treated and coronally reduced to the cemento-enamel junction. During the experimental period the teeth were stored in saline. All specimens were randomly assigned to four experimental groups of ten samples each. In group A the fiber posts were sand-blasted and cemented with Panavia F. In group B the posts were cemented without sand-blasting. Group C received sand-blasted fiber-posts cemented with Ketac-Cem. In group D the posts were cemented without sand-blasting. Post holes were prepared according to manufacturers' instructions. The fiber posts (Mirafit Carbon) were then cemented with one of the two cements as recommended. Retentive strength was measured 24 hours after cementation using a universal testing machine.
Results: The following mean retentive strengths in Newtons for the different groups were: group A: 448.4 N (+/- 105.9 N); group B: 395.7 N (+/- 99.9 N); group C: 210.9 N (+/- 66.5 N); group D: 176.8 N (+/- 67.2 N). Retentive strength in group A and B (Panavia F) was significantly increased compared to group C and D (Ketac-Cem) (p< 0.05, Tukey xs test). The influence of sandblasting was for both cements not significant.
Conclusions: The reconstruction of endodontically treated single rooted teeth with fiber posts showed acceptable retentive values for all cementation modalities used in this study. The values observed for the composite cement Panavia F were significantly higher compared to the conventional cement Ketac-Cem.

Purpose: The purpose of this study was to compare the load fatigue of 3 dowel and core systems.
Methods: Fifteen endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 1.5mm incisal to the CEJ. At the level of the CEJ, specimens were then prepared for crowns with 1mm complete shoulder finish lines and 1.5mm of axial wall height. The prepared teeth were divided into three groups (n=5) and restored with one of of the following dowel and core combinations: Group CG, cast gold dowels and cores, Group TA, Titanium Alloy dowels (ParaPost XH) with composite cores, or Group FR, fiber-reinforced resin dowels (ParaPost FiberWhite) with composite cores. A dentin bonding agent (Optibond Solo) was placed prior to the composite cores. Dowel and core castings and Titanium alloy dowels were cemented with zinc phosphate cement. The fiber-reinforced dowels were cemented with a resin cement (ParaPost Cement). The crowns for all specimens were cast with an incisal notch for applying the fatigue load. The independent variable was the number of load fatigue cycles required to cause luting cement failure. The data were subjected to 1-way analysis of variance and the Student-Newman-Keuls test for 3 subsets (a=.05).
Results: The mean value +/- standard deviation for the cycles to failure for each group was Group CG: 11,897 +/- 4080 load cycles, Group TA: 24,384 +/- 8231 load cycles, and Group FR: 50,696 +/- 7063 load cycles. Significant differences were found between all groups (P<.05).
Conclusions: Fiber-reinforced dowels and bonded composite cores under fatigue loading provided significantly stronger crown retention than cast gold dowels and Titanium Alloy dowels with composite cores.

Objectives: The aim of the study was to evaluate the retention of prefabricated root canal posts made of a variety of materials that have recently been introduced to dentistry.
Methods: The posts studied were Cosmopost (ceramic), Composipost / C-POST (Carbon fibers), Aestheti-Plus post (Quartz Fibers), Light-Post (Quartz fibers) and ParaPost White (glass fibers). The posts were luted in extracted human pre-molars and the cores were built up with the resin composites recommended by the (post) manufacturers. The retention of individually cast gold alloy posts luted with zinc phosphate cement were used as reference. A universal testing machine was used to determine the retention of each cemented post. Data were compared using ANOVA supplemented with Fisher’s PLSD at a significance level of p<0.05.
Results: Only the Cosmopost system exhibited retention values that were significantly lower than for the conventional cast gold alloy posts luted with zinc phosphate cement. The force necessary to loosen the Cosmopost specimens was significantly less than that needed to loosen the Aestheti-Plus post (p<0.05) and the Light-Post systems (p<0.01). The force necessary to loosen the ParaPost White specimens was significantly less than for the Light-Post system (p<0.01). Other combinations did not differ significantly (p<0.05).

Abstract/conclusions: The retention in root canals of serrated carbon fiber Composiposts and stainless steel Paraposts was tested under tensile load. Twenty unrestored human roots were endodontically prepared and root filled. Two groups of 10 roots received 1.4-mm Composiposts or 1.25-mm Paraposts luted with a resin cement. The specimens were then embedded in acrylic resin and mounted in an Instron machine. The tensile force (kg) required to dislodge the posts was recorded and analyzed with Student's t test. The results revealed that there was no significant difference in the retention of either post (P > .05). The rigidity of ten 1.4 mm serrated Composiposts was tested in a three-point bend test in an Instron machine, and the retention of composite cores to 10 of these posts under tensile force was also tested. The results from these tests were compared to previous data from the authors' laboratory and revealed that the serrations significantly reduced the rigidity of the post (P < .001) and increased the retention of a core material (P < .001).

This study evaluated the bond strength of a light- and self-cured adhesive system to different intraradicular dentin areas (cervical, middle and apical thirds). Twenty single-rooted teeth were instrumented and their roots were prepared to receive a #2 translucent fiber post (Light Post). The root canals were irrigated with 0.5% sodium hypochlorite for one minute, rinsed with water and dried using paper tips. The teeth were divided into two groups (n=10): Single Bond [SB] (light-cured) and Scotchbond Multi-Purpose Plus [SBMP] (self-cured). To avoid polymerization of the materials through the root lateral walls, the teeth were placed in a silicone mold and the adhesives applied with a thin microbrush according to manufacturer's instructions. The resin cement, Rely X ARC, was inserted into the root canals using Lentulo burs. The post was then placed and the light-curing procedure was carried out for 40 seconds (+/-500 mW/cm2). The roots were kept in a 100% relative moisture environment for 24 hours and stored in distilled water for an additional 24 hours. Each root was perpendicularly sectioned into 1-mm thick sections, resulting in approximately four slices per region. Dumbbell-shaped slices were obtained by trimming the proximal surfaces of each slice using a diamond bur until it touched the post. The bonded area was calculated, slices were attached to a special device and submitted to microtensile testing at 1 mm/minute crosshead speed. Data were analyzed using ANOVA and Tukey's test. The mean bond strength values (MPa) were: SBMP: cervical=10.8a, middle=7.9b%, apical=7.1bc; SB: cervical=8.1b, middle=6.0c, apical=6.9b. Significant differences were found between adhesive systems only for the cervical third. The cervical region showed higher mean bond strength values than the middle and apical regions (p<0.0001).

Statement of problem: The use of fiber-reinforced composite resin posts in endodontically treated teeth has increased. However, selecting an adhesive system that provides reliable and long-lasting bonding to root canal dentin remains difficult.
Purpose: This study evaluated the microtensile bond strength of 2 adhesive systems to root dentin and 2 different fiber-reinforced composite resin posts.
Methods: Forty single-rooted teeth were instrumented, and root canals were prepared for translucent (Light Post [LP]) or opaque (Aestheti Post [AP]) quartz fiber-reinforced composite resin posts. Two adhesive systems were used: Scotchbond Multi-Purpose Plus (SBMP) (autopolymerized) as a control group, and Single Bond (SB) (photoactivated). Teeth were assigned to 4 groups (n=10): SBMP+LP, SBMP+AP, SB+LP, SB+AP. After post cementation, roots were perpendicularly sectioned into 1-mm-thick slices, which were trimmed to obtain dumbbell-shaped specimens. The specimens were divided into 3 regions: cervical (C), middle (M), and apical (A). To determine the bond strength, the bonding area of each specimen was calculated, and specimens were attached to a device to test microtensile strength at a crosshead speed of 1 mm/min. Data were analyzed using 3-way analysis of variance and the Tukey test (alpha=.05). Fractured specimens were examined under a x 25 stereomicroscope to determine the mode of fracture.
Results: There were significant differences only among root dentin regions (P<.001). The cervical third (9.16 +/- 1.18 MPa) presented higher mean bond strength values, especially for SBMP. Middle and apical regions demonstrated lower values (7.08 +/- 0.92 and 7.31 +/- 0.60 MPa, respectively). Adhesive and post main factors did not demonstrate significance. Also, no interaction was significant. No cohesive fractures within resin cement, fiber-reinforced composite resin post, or root dentin were identified.
Conclusions: Both adhesive systems tested demonstrated reliable bonding when used with translucent and opaque fiber-reinforced composite posts.

Abstract/conclusions: Core-post retention is dependent on post head surface geometries. The purpose of this study was to compare the retention of smooth-surface metal and non-metal post-core assemblies. Thirty smooth-surface post head samples measuring approx. 1.45mm in diameter were separated into 3 groups of 10 samples, according to type of post: Group A; Composipost, Group B; Zirconium Ceraposts, Group C; Cast silver palladium. Post heads were uniformly sanded with aluminum oxide (50um). Prior to core formation, all posts were pretreated with ALL-BOND 2. Core-post assemblies were made with Bis-Core in special molds (Teflon), with the post head 1mm from the top surface of the core covering. All samples were allowed to set for 96 hours. Tensile failure loads were measured in the absence of crowns using an Instron test machine (4505) at a cross-head speed of 25mm/min. Values were recorded in pounds. Mean values were analyzed with a one-way ANOVA. There was a significant interaction between posts. Metal posts (111 +/- 17 lbs) and Composiposts (120 +/-16 lbs) were most retentive and displayed significantly greater retention than Zirconium posts (45 +/-20lbs).

Abstract/conclusions: Forty-two single-rooted lower premolars, extracted for periodontal reasons, were endodontically treated and divided into 7 groups of 6 teeth each. In five of the groups, three different types of carbon fiber posts (Composipost), quartz fiber posts (Aestheti-Plus), and titanium posts were used in combination with ALL- BOND 2 dental adhesive. In two groups, two types of carbon fiber posts were also cemented with Panavia 21 dental adhesive. After 3 wk storage in saline, the teeth were longitudinally sectioned; one half was observed using confocal microscopy and the other by scanning electron microscopy. The specimens were evaluated for the presence of a resin dentin interdiffusion zone for the presence of voids at post-resin-dentin interfaces and for the determination of the fiber posts' structure. Upon examination with the confocal microscope, the interfaces of teeth restored wtih ALL- BOND 2 showed a higher percentage (p<0.05) of resin dentin interdiffusion zone than those treated with Panavia. The fiber size and the post structure were similar in all the fiber posts observed.

Purpose: The purpose of this study was to evaluate the effect of the degree of mismatch between post space and post diameters on the bond strength of a fiber-reinforced resin post.
Methods: Thirty-two extracted human maxillary central incisors and canines were endodontically treated and assigned to four groups: Group 1--Canal prepared with a D.T. Light Post #1 drill (control); Group 2--Canal prepared with a D.T. Light Post #2 drill; Group 3--Canal prepared with a D.T. Light Post #3 drill; Group 4--Canal prepared with a Gates Glidden #6 drill. A D.T. Light Post size 1 was then luted into the canal using One-Step Adhesive and Post Cement Hi-X. A push-out test was performed on three sections of each root to measure push-out bond strengths. Data were analyzed with ANOVA and Bonferroni's test at p < 0.05. Two extra teeth for each group were restored in the same fashion and processed for SEM observation.
Results: (in MPa): Group 1: 15.7 +/- 6.9; Group 2: 14.7 +/- 6.5; Group 3: 14.0 +/- 5.0; Group 4: 14.0 +/- 5.1. The variable "post space" resulted in no statistically significant difference in mean bond strengths (p > 0.05). For the variable "root region," the coronal third (17.5 +/- 6.0) resulted in statistically greater mean bond strengths than the apical third (12.3 +/- 6.0) at p < 0.008. The middle third (14.0 +/- 5.3) resulted in no statistically significant different mean bond strengths from the coronal third at p > 0.119 and from the apical third at p > 0.999. Under the SEM, some areas of the canal system still displayed residual gutta-percha, which resulted in debonding of the interface between the resin cement and dentin. Areas with incomplete dentin hybridization were observed in localized areas of all groups.
Conclusions: The diameter of the post space did not affect the push-out bond strengths. Bonding at the coronal level of the root canal is more reliable than bonding at the apical level. The presence of residual gutta-percha and the deficient dentin hybridization may result in deficient seal of the resin-dentin interface.

This study aimed to evaluate the influence of cement thickness on the bond strength of a fiber-reinforced composite (FRC) post system (Light-Post, RTD , St Egreve, France)to the root dentin. Eighteen single-rooted human teeth were decoronated (length: 16 mm), the canals were prepared, and the specimens were randomly allocated to 2 groups (n = 9): group 1 (low cement thickness), in which size 3 FRC posts were cemented using adhesive plus resin cement; and group 2 (high cement thickness), in which size 1 FRC posts were cemented as in group 1. Specimens were sectioned, producing 5 samples (thickness: 1.5 mm). For cement thickness evaluation, photographs of the samples were taken using an optical microscope, and the images were analyzed. Each sample was tested in push-out, and data were statistically analyzed. Bond strengths of groups 1 and 2 did not show significant differences (P = .558), but the cement thicknesses for these groups were significantly different (P < .0001). The increase in cement thickness did not significantly affect the bond strength (r2 = 0.1389, P= .936). Increased cement thickness surrounding the FRC post did not impair the bond strength.

Objectives: Nowadays, the restoration of endodontically treated teeth is based on the use of materials with a modulus of elasticity similar to that of dentin (18.6 GPa). Fiber posts, resin cements and some composite resins all have this characteristic. This study evaluated the bond strength between luting materials, root dentin and fiber posts through push-out tests and examined the integration among these three components through scanning electron microscopy.
Method: Endodontically treated extracted teeth and plastic plates were used to test the interface between luting agent and dentin and dentin and luting agent and post.
Results: Chemical affinity between different components (luting materials and fiber posts) is extremely important in achieving high bond strength. The bond strength tests and SEM observations showed that in-vitro, composite resins perform better than resin cements.
Conclusions: Adhesive luting of posts is an alternative technique that is comparable and in some ways superior to the traditional technique that uses resin cements. Composite resins are easy to use and ergonomically advantageous because the same material can be used to lute the post and restore the core. Particular attention should be paid to the association between translucent posts and light-cured composite resins. This technique has the advantage of prolonged working time. Further investigation is needed to demonstrate the complete conversion of light-cured composite at different depths.
Significance: The in vivo use of these materials may significantly reinforce residual tooth structure therefore reducing the risk for fracture and debonding.

Clinical Relevance: With respect to the adhesion properties of carbon fiber posts and glass fiber posts used in the restoration of endodontically - treated teeth, they perform equally well if used in combination with chemically cured luting cements or with light- activated ones. Summary: Fiber posts are used widely in the restoration of endodontically - treated teeth. Scientific evidence demonstrates that the mechanical performance of teeth restored with fiber posts in combination with resin luting cements is improved with respect to metallic post restorations. The post is cemented inside the root canal using low-modulus elastic polymer resins. In this study, the mechanical resistance of four different post – cement systems (1. carbon fiber C-Post/Composipost (Bisco Dental / RTD) with C&B chemically-cured cement (Bisco Dental), 2. carbon fiber/glass fiber Aestheti-Plus (Bisco Dental / RTD) post with C & B cement, 3. glass fiber Aestheti-Plus Post (Bisco Dental / RTD) with C&B cement, and 4. quartz fiber Light-Post (Bisco Dental / RTD) with dual-curing Duo-Link cement (Bisco Dental) was assessed by means of a micro-mechanical pull-out test assisted by a simulation using the Finite Element methodology. This in vitro test is specifically designed to accurately characterize the post/cement interface. The results show no significant difference among the adhesion of the various types of post – cement systems used.

Objective: this study investigated the effects of thermocycling on the retention of glass fiber and resin posts.
Methods: Forty premolar and canine tooth roots were imbedded in acrylic blocks shaped to fit into a retention device. The roots were randomly assigned to two groups of 20 to receive either Light-Posts (RTD) or Lucent Anchors (Dentatus) which were cemented into 9mm deep post spaces, with Panavia F resin cement. Each group was divided into two equal subgroups; one for thermocycling and the other to serve as a control. The thermocycled specimens were cycled 300 times between water baths at 5 degrees C and 55 degrees C, with a dwell time of 60 seconds in each. Control specimens were stored at 37 degrees C. The tensile force required to dislodge each post from its root was recorded and the data analyzed using Student’s T-Tests.
Results: There were no significant differences between the control and the thermocycled specimens. Light-Posts were significantly more retentive than the Lucent Anchor without thermocycling, but that distinction was not that apparent in the thermocycled groups.
Conclusions: Glass-fiber-and-resin posts cemented with resin cement offer acceptable levels of retention and are not susceptible to reduced retention from thermocycling. Thermocycling should be given less emphasis in tests for the retention of root canal posts cemented with resin cements.

Objective: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using Titanium posts as controls.
Methods: Sixty recently extracted single rooted caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of ten for post preparation. Post space preparation was carried out according to manufacturer’s instructions. All posts were bonded using Panavia F. A 4mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a crosshead speed of 5mm/min.were recorded.
Results: It was found that the parallel-sided Light-Post (RTD, St Egreve, France) were significantly more retentive than all of the other posts. ParaPost Fiber White was more retentive than tapered Light-Posts and Snow Posts. There was no significant difference between the retention of the stainless steel ParaPost and any of the other groups.
Conclusions: Serrated, parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. Due to the nature of the bonding mechanism, the shape of the tooth-colored post may be less significant to its retention than it is for metal posts.

Objectives: This study evaluated the effect of the mechanical cycling on the bond strength of fiber posts resin bonded to root dentin.
Methods: The tooth crown of the 60 single-rooted human teeth was cut, leaving a 16-mm long root specimens (sp) that were endondontically treated and the space prepared in 12mm. Thirty sp received a quartz fiber post (D.T. Light-Post) and 30 sp received a glass fiber post (FRC Postec Plus). The posts were resin luted in the post space and each sp was embedded with epoxy resin (resin 285, Schaller, Florence, Italy) in a PVC cylinder (height: 25 mm, diameter: 10 mm). Sp were divided into 6 groups, considering the fiber post type and number of the mechanical cycles (load: 50 N; angle of 45°; frequency: 8Hz): G1- DT + without cycling; G2- DT + 20,000 cycles; G3- DT + 2,000,000 cycles; G4- FRC + without cycling; G5- FRC + 20,000 cycles; G6- FRC + 2,000,000 cycles. The sp were cut perpendicular to their long axis, to form 2-mm-thick disk-samples (4 sections / sp), which were submitted to the push-out test (1mm/min). The mean bond strength values were calculated for each tooth (n=10) and data were statistical analyzed (alpha=.05).
Results: ANOVA revealed that: (a) the bond strengths of DT (7,12 ± 2,20 MPa) and of FRC (6,87 ± 2,12 MPa) were statistically similar (P=0,665); (b) the mean values for the “without cycling” groups (6,96 ± 2,44 MPa), “20,000 cycles” groups (6,99 ± 2,08 MPa) and “2,000,000 cycles” groups (7,02 ± 2,00 MPa) were not statistically different (P=0,996); (c) the 6 groups were not statistically different (P=1,000).
Conclusion: the mechanical cycling did not affect the bond strength of two fiber posts resin bonded to dentin.

Objectives: To evaluate the microtensile bond strengths of different resin composites used as core materials around fiber posts.
Methods: Forty DT Light-Posts (RTD) were randomly divided into eight groups, according to the resin composite used. They included two core materials specifically developed for core build-up--Group 1: Core-Flo (Bisco Inc.) and Group 2: UniFil Core (GC Corp.); three hybrid composites--Group 3: Tetric Ceram (Ivoclar-Vivadent), Group 4: Gradia Direct (GC Corp.), Group 5: Bisfil 2B (Bisco, Inc.); and three flowable composites--Group 6: AEliteflo (Bisco, Inc.), Group 7: Filtek Flow (3M ESPE) and Group 8: UniFil Flow (GC Corp). A cylindrical plastic matrix was placed around the silanized post and filled with the respective resin composite. Each bonded post provided five to eight sticks for microtensile testing. Each stick was loaded to failure under tension at a cross-head speed of 0.5mm/min. One-way ANOVA and Tukey's test were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks.
Results: Resin composites exhibited a significant influence on microtensile bond strength (p<0.05). Core-Flo showed the highest bond strength (11.00+/-0.69 MPa) although it was not statistically significantly different from all groups, except from the flowable composites. Under SEM, all the composites adapted well to the fiber post, with a variable extent of voids observed along the fractured composite interfaces.
Significance: Although good adaptation to the post surface was achieved, bond strength to fiber post remains relatively weak. Core build-up and hybrid composites are better alternatives to flowable composites as core build-up materials.

Purpose: The aim of this study was to evaluate the influence of the operator's experience on the outcome of fiber post cementation using an etch-and-rinse acetone-based adhesive.
Methods: Fifteen human anterior teeth were used in the study. One trained operator performed the endodontic procedures and prepared the roots for the insertion and cementation of the posts. At this point, teeth were divided into 3 groups and distributed to 3 operators to lute the posts: an expert operator (EO), a moderately experienced operator (ME), and an operator with a low level of experience (LE). Quartz fiber posts (DT Light Post #1 or #2, RTD) were used. Posts were cemented using Prime&Bond NT Dual Cure adhesive system (Dentsply Caulk) in combination with the dual-curing resin cement Calibra (Dentsply Caulk). The post retention was assessed with the "thin-slice" push-out test. One-way ANOVA was performed to examine the effect of the operator on push-out strength, followed by post-hoc multiple comparisons using Tukey's test, with the significance level set at alpha = 95%.
Results: The results of push-out strength testing were as follows: EO (12.44+/-3.63 MPa), ME (11.68+/-2.64 MPa), LE (11.18+/-3.12 MPa). No statistically significant differ -ences were determined among the three groups.
Conclusions: There was no statistically significant difference in the retention measured for fiber posts luted by operators with different levels of clinical experience. Given the parameters of this investigation, the level of operator experience in luting fiber posts does not affect post retention under laboratory conditions.

Purpose: The aim of this study was to evaluate the influence of the operator's experience on the outcome of fiber post cementation using an etch-and-rinse acetone-based adhesive.
Methods: Fifteen human anterior teeth were used in the study. One trained operator performed the endodontic procedures and prepared the roots for the insertion and cementation of the posts. At this point, teeth were divided into 3 groups and distributed to 3 operators to lute the posts: an expert operator (EO), a moderately experienced operator (ME), and an operator with a low level of experience (LE). Quartz fiber posts (DT Light Post #1 or #2, RTD) were used. Posts were cemented using Prime&Bond NT Dual Cure adhesive system (Dentsply Caulk) in combination with the dual-curing resin cement Calibra (Dentsply Caulk). The post retention was assessed with the "thin-slice" push-out test. One-way ANOVA was performed to examine the effect of the operator on push-out strength, followed by post-hoc multiple comparisons using Tukey's test, with the significance level set at alpha = 95%.
Results: The results of push-out strength testing were as follows: EO (12.44+/-3.63 MPa), ME (11.68+/-2.64 MPa), LE (11.18+/-3.12 MPa). No statistically significant differ -ences were determined among the three groups.
Conclusions: There was no statistically significant difference in the retention measured for fiber posts luted by operators with different levels of clinical experience. Given the parameters of this investigation, the level of operator experience in luting fiber posts does not affect post retention under laboratory conditions.

Tooth-coloured adhesive inserted fiber posts are used to restore endodontically treated teeth. In this investigation, the tensile bond strength of two different fiber posts systems (ER DentinPost and DT Light Post) in combination with five different resin cements was tested. The posts were inserted into artificial root canals in bovine dentin using Clearfil Core, RelyX Unicem, Panavia 21ex, Panavia F2.0 und Calibra. Titan posts (ER-Kopfstift), inserted with zincphosphate cement served as control group. ER DentinPost inserted with Clearfil Core had significantly higher tensile bond strengths than in combination with Panavia F2.0 (221.70 +/- 17.99 N) or Calibra (212.37 +/- 45.20 N). DT Light Post in combination with Calibra (338.20 +/- 46.40 N), Panavia F2.0 (321.69 +/- 40.11 N) and Panavia 21ex (290.41 +/- 55.28 N) showed significantly higher tensile bond strengths compared to adhesive cementation with RelyX Unicem (211.57 +/- 32.35 N) and Clearfil Core (131.67 +/- 51.72 N). The tensile bond strength of the control group was in the upper third of the values (315.43 +/- 51.38 N). Optical analysis of the post surface after decementation demonstrated in all cases adhesive-cohesive mixed fractures. The adhesion of resin cement to the fiber posts and resin cement to root canal dentin is influenced by different factors. The combination of fiber post systems with the type of resin cement has a great influence on the tensile bond strength.

Abstract: This study evaluated the tensile bond strengths and the effect of silanization of fiber posts inserted with different adhesive systems. Sixty DT Light-Posts (size 1) were used. Thirty posts were pretreated with silane. The posts were cemented into form-congruent artificial root canals (12 mm) of bovine dentine. Six groups were formed: G1, Prime&Bond NT/Calibra; G2, Monobond-S+Prime&Bond NT/Calibra; G3, ED Primer/Panavia 21ex; G4, Monobond-S+ED Primer/Panavia 21ex; G5, RelyX Unicem; and G6, Monobond-S+RelyX Unicem. The mean (standard deviation) tensile bond strengths (megapascals) were 7.69 (0.85) for G1, 7.15 (1.01) for G2, 6.73 (0.85) for G3, 6.78 (0.97) for G4, 4.79 (0.58) for G5, and 4.74 (0.88) for G6. G1 achieved significantly higher bond strengths than G3 and G5; G3 had significantly higher values than G5 (P < .05; Scheffé procedure). Silanization had no significant effect (P > .05, one-way analysis of variance). Tensile bond strengths were significantly influenced by the type of resin cement. Silanization of fiber post surfaces seems to have no clinical relevance.

Statement of problem: A number of prefabricated nonmetallic posts are currently available for use in conjunction with resin composite cores before fabrication of crowns for endodontically treated teeth. Information is needed regarding the strength of the composite and the nature of attachment between its components.
Purpose: The aim of this study was to determine the influence of different types of posts on the fracture resistance of a resin composite core material using the diametral tensile strength (DTS) test.
Methods: Cylindrical specimens, 6 mm in diameter and 3 mm high, were prepared from resin composite (Tetric Ceram) and a group of prefabricated posts (n=10) as follows: resin composite only (control); Vectrispost (VTS); FiberKor (FKR); Aestheti-Plus post (ATP); Light-Post (LTP); Dentorama post (DRM), and Para-Post (PRP) as a second control. Specimens were stored for 7 days in water at 37 degrees C and then subjected to DTS test in a universal testing machine until failure occurred and load was recorded (N). Mean values and SD for DTS values (MPA) were calculated, and data were analyzed statistically with 1-way analysis of variance, followed by the Tukey test (alpha=.05). Representative specimens from each group were examined with SEM to determine nature of failure.
Results: Mean values (SD) in MPa for DTS were as follow: Control group: 49.64 (3.36); VTS: 29.77 (3.36); FKR: 31.9 (2.39); ATP: 28.92 (2.2); LTP: 34.26 (3.37); DRM: 33.45 (2.46), and PRP: 27.90 (2.40). Analysis of variance indicated significant differences among the groups (P<.05). SEM examination indicated that for PRP failure was adhesive in nature, whereas with all nonmetallic posts, cohesive failure was more predominant.
Conclusion: The use of posts did not result in reinforcement of resin composite core when diametral tensile force was applied. When used with the core material, LTP, DRM, and FKR resulted in the highest DTS values, whereas PRP resulted in the lowest values.
Clinical Implications: Some non-metallic fiber-reinforced posts, when used with a resin composite core, resulted in significantly higher Diametral Tensile Strength (DTS) compared with metal prefabricated posts. These higher DTS values meet minimum accepted values as provided by the ADA specifications for direct Type II composite materials.

Objectives: Composites are used in post-endodontic core rebuildings when carbon and/or quartz fiber posts have been luted in root canals. Which composite is able to give the best clinical results in core rebuilding is still being discussed. The purpose of this study is to compare the adhesion of different composites to the surface of both carbon and quartz fiber posts.
Methods: Two dual-curing (CoreRestore2 : Kerr & Luxacore:DMG) and two light-curing composites (Light-Core:Bisco & HelioMolar: Vivadent) were used to build a core on quartz fiber posts (Light-Post: RTD/Bisco). Posts were etched with Hydrofluoric acid 9.6% for 10 seconds. Two dual-curing (CoreRestore2 & BisCore: Bisco) and two light-curing composites (Renew: Bisco & Heliomolar) were used on carbon fiber posts (RTD/Bisco). In all, 8 groups of 10 specimens each were prepared. All the cores were built by using the same form (Composipost Core Form: RTD). Three slices (2.5mm thickness) in each specimen were obtained by using Leitz 600 device, and pull-out tests with Instron machine were performed.
Results: on quartz fiber posts, CoreRestore 2: 393.9 N-29.02 MPa, Luxacore: 347 N-25.52 MPa, Light-Core: 313.7 N-21.31 MPa, Heliomolar: 182.4 N-13.22 MPa. On carbon fiber posts CoreRestore 2: 236.3 N-216.67 MPa, Bis-Core: 235.5 N-16.66 MPa, Renew: 234.8 N-16.61 MPa, Heliomolar: 228.6 N-16.15 MPa.
Conclusions: The above results show that 1) the adhesion of composite resins to quartz fiber posts is higher than to carbon fiber posts, 2) on quartz fiber posts, dual-curing composites lead to a stronger adhesion that light–curing composites and 3) on carbon fiber posts, only negligible differences exist between dual and light-curing composites.

Adhesive reconstruction of endodontically treated teeth using fiber posts and resin composite materials has become increasingly popular. Recommendations include pre-treating the post with adhesive and/or silane. However, since the fiber post has a rough surface and is highly polymerized, it is questionable whether this step contributes to the bond. The diametral compression test (DCT) can be used to indirectly determine he bond of composite to a post (Santos JPD 91:335-41,2004).
Objective: to determine the effect of various surface treatments on the bond of resin composite to fiber posts by DCT.
Methods: Cylinders of resin composite (Z100, 3M ESPE, St. Paul, MN), were formed around the coronal end of three different fiberposts: DT Light-Post (Bisco/RTD), RelyX (3M ESPE) and UniCore (Ultradent). Four conditions (n=5) were tested: post surface untreated (Untx); cleaned with EtOH; cleaned and primed with All-Bond 2 (AB2); post coated with Vaseline to prevent bonding (Vas). A solid cylinder of composite (Sol) was used as a control (n=5). Samples were loaded to failure in diametral compression on an Instron Universal Testing Machine at a crosshead speed of 1 mm/min. DTS was calculated according to the formula: 2P/π*D*T. Means were compared with ANOVA and Fisher's PLSD (alpha = 0.05).
Results: Means in MPa (s.d) are given in the table. Means with the same superscript are not significantly different. Due to slight variations in size, comparisons between posts were not possible.

	Solid cylinder	AB2	AB2	EtOH	Vaseline
DT	28.7 (5.17)a	27.8(5.75)a	27.3 (2.30)a	24.27(1.05)a	12.4(1.30)b
RelyX	28.7 (5.17)a	30.4(2.89)a	27.5(3.62)a,b	25.7(3.35)a,b	14.2 (1.84)c
UniCore	28.7 (5.17)a	26.2(3.11)a	20.0(3.14)b	18.8(2.74)b	13.6(2.34)c

Conclusions: For two of the three posts there was no statistically significant difference in bond regardless of surface treatment, but treatment of the post with a dentin bonding agent resulted in the highest bond strength to resin composite in all cases.

Purpose: To evaluate the influence of surface treatments on microtensile bond strength of luting resin cements to fiber posts.
Methods: 42 quartz-fiber posts (Light Post, RTD) were divided into 7 groups (n=6) according to the surface treatment performed. I and II: experimental patented industrial coating (RTD); III: industrial coating followed by adhesive application (XPBond, Dentsply Caulk); IV: adhesive (XPBond); V: adhesive (Prime&Bond NT, Dentsply Caulk); VI: silane (Calibra Silane, Dentsply Caulk); VII: no treatment (control). Adhesives were used in self-cure mode. Two resin cements (Sealbond, RTD – Group I and Calibra, Dentsply Caulk – Groups II-VII) were applied on the posts to produce cylindrical specimens. One cylinder from each group was randomly chosen for SEM evaluation. Cylinders were cut to obtain microtensile sticks that were loaded in tension at a cross-head speed of 0.5 mm/min until failure. Statistical analysis was performed using Kruskal-Wallis analysis of variance followed by the Dunn's multiple range test for the post-hoc comparisons (p<0.05).
Results: The post-cement bond strength was significantly higher on fiber posts coated industrially or treated with XPBond adhesive when compared to Prime&Bond NT application, silanization or no treatment of conventional fiber posts (Table 1). Additional adhesive application did not influence bond strength on industrially coated posts.
Conclusion: Both the experimental industrial surface treatment and the adhesive application enhanced fiber post to resin cement interfacial strength. Industrial treatment may simplify the clinical luting procedure.

Table 1: Post-cement microtensile bond strength. Numbers are means. Values in brackets are standard deviations. Different superscript letters indicate statistically significant differences.

Group	Surface treatment	Cement	µTBS (MPa)
I	Industrial coating	Sealbond	23.14 [8.05] A
II	Industrial coating	Calibra	21.56 [7.07] A
III	Industrial coating+XPBond	Calibra	22.37 [7.00] A
IV	XPBond	Calibra	21.03 [5.34] A
V	Prime & Bond NT	Calibra	14.05 [5.06] B
VI	Calibra Silane	Calibra	6.31 [4.60] C
VII	No treatment	Calibra	4.62 [4.31] C

Group Surface treatment Cement µTBS (MPa)
I Industrial coating Sealbond 23.14 [8.05]A
II Industrial coating Calibra 21.56 [7.07]A
III Industrial coating+XPBond Calibra 22.37 [7.00]A
IV XPBond Calibra 21.03 [5.34]A
V Prime & Bond NT Calibra 14.05 [5.06]B
VI Calibra Silane Calibra 6.31 [4.60]C
VII No treatment Calibra 4.62 [4.31]C

Objectives: The purpose of this study was to determine the modes of failure and bond strength between quartz fiber post (Æstheti-Plus, R.T.D., France) and core build up materials (light cure composite resin, Alphadent, Dental Technologies, Inc., USA).
Methods: Sixty quartz fiber posts were placed in extracted premolar and core were built up with light cure composite resin. Specimens were classified into 6 groups due to three diameters; 1.4, 1.8 and 2.1 millimeters at different heights; 2 and 4 millimeters. Universal Testing Machine (Lloyd LR30K, Lloyd Instruments, Ltd., England) was performed at the angulation of 45 degrees to the long axis of the tooth with cross head speed 0.2 millimeters/second. Each specimen was continuously loaded until fracture occurred.
Results: It was found that the median load that caused core fracture out until fracture out of the post diameter 1.4, 1.8, and 2.1 millimeters were 244.3 N (95% CI: 218.2 N to 300.8 N), 393.5 N (95% CI: 373.8 N to 423.4 N), and 376.6 N (95% CI: 354.6N to 433.3N) respectively. The median fracture load measured from different post diameters was significantly different (P-value <0.001) whereas the load from various post heights was not significantly different (P-value=0.459). The modes of failure occurred between composite resin and post dentine (91.7%). No fractures were found within root, coronal tooth structure and post.
Conclusions: From this study, it could be concluded that quartz fibers posts would not cause any coronal tooth structure and/or root fracture. Post diameter 1.8 and 2.1 were recommended due to higher bond strength between post and core materials.

Endodontically treated teeth often have little coronal tooth tissue remaining and as such require a post to retain the core and the restoration. Therefore, tooth coloured adhesive inserted fiber posts in combination with resin based core material can be used. In this study, the tensile bond strength of core materials to fiber posts was investigated. Three different core materials, Clearfil Core, CoreRestore 2 and MultiCore Flow in combination with two different fiber posts systems, ER DentinPost and DT Light Post, were tested. The posts were shortened to the lengths of 15 mm.The specimens were obtained while the upper part (3 mm) of the posts was covered with standardized cylinders of the core materials. Clearfil Core in combination with the DT Light Post (230.5 N +/- 42.2 N) and ER DentinPost (154. N +/- 33.6 N) had the highest tensile bond strengths of all groups. The tensile bond strength of CoreRestore 2 to DT Light Post (149.9 N +/- 29.5 N) was higher than the tensile bond strengths of the combinations MultiCore Flow/DT Light Post (140.9 N +/- 31.4 N) and Multi- Core Flow/ER DentinPost (122,. N +/-19,. N). The group Core-Restore DentinPost had the lowest tensile bond strengths (80,1 N ++/-19,4 N). The adhesion of the resin based core materials to the fiber posts is influenced by the post design and core materials. The combination of core materials with the type of fiber post has a great influence on the tensile bond strength.