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Purpose: This study aimed to assess the impact of battery levels in single-peak and multi-peak light-curing units (LCUs) on irradiance, and their effects on glass fiber post push-out bond strength to root dentin and the degree of conversion of dual-cure universal resin cement., Methods and Materials: Sixty bovine roots underwent endodontic treatment and were randomly distributed into 6 groups (n=10), formed by combining two LCUs (single-peak and multipeak) and three battery levels (100%, 50%, and 10%). A spectrophotometer measured irradiance (mW/ cm2) and spectral irradiance (mW/cm2/nm). Push-out bond strength (PBS) tests occurred at three root regions (cervical, middle, and apical), with optical and scanning electron microscopy for failure mode analysis. Degree of conversion (DC) was evaluated across the root regions. Data were analyzed using two-way repeated measures ANOVA and the Tukey HSD test. The Fisher exact test verified failure modes (α=0.05)., Results: As multipeak LCU battery levels decreased, emitted irradiance also diminished, with notable PBS reductions in the apical thirds. Failure modes were influenced by different conditions, primarily exhibiting mixed modes. Battery levels significantly impacted DC in the multipeak LCU, particularly in the cervical region, while the single-peak LCU exhibited DC reduction at the 10% battery level in the cervical region., Conclusions: Emitted irradiance, resin cement DC, and glass fiber post bond strength to root dentin may be influenced by varying cordless LCUs and battery levels., (©Operative Dentistry, 2024.)

The purpose of this study was to evaluate the push-out bond strength of two different adhesive cements (total etch and self-adhesive) for glass fiber post (GFP) cementation in simulated, long-term service (thermocycling) when the root canal is treated with chlorhexidine before cementation. One hundred twenty premolar specimens with a single root canal were selected, endodontically treated, and shaped for GFP cementation (n=120). The specimens were randomly placed into one of 12 groups (10 specimens each) according to cement (T = total-etch RelyX ARC or S = self-adhesive RelyX Unicem), treatment with chlorhexidine (N or Y: without or with), and number of thermal cycles (00, 20, or 40: 0, or 20,000 or 40,000 cycles): 1. TN00, 2. TN20, 3. TN40, 4. TY00, 5. TY20, 6. TY40, 7. SN00, 8. SN20, 9. SN40, 10. SY00, 11. SY20, 12. SY40. The root of each specimen was cut perpendicular to the vertical axis, yielding six 1.0 mm-thick sections. A push-out bond strength test was performed followed by statistical analysis using a factorial analysis of variance. Pairwise comparisons of significant factor interactions were adjusted using the Tukey test. Significant differences of push-out bond strengths were found in the four main effects (resin cement [ p<0.0001], treatment with chlorhexidine [ p<0.0001], number of cycles [ p<0.0001], and root third [ p<0.0001]) and all interactions ( p<0.05 for all). Both resin cements produced higher bond strength in the cervical third followed by the middle third, and lower values were detected in the apical third. Additionally, the results suggest that the use of an additional disinfection treatment with chlorhexidine before the cement application produced the highest push-out bond strength regardless of root third. Further, the thermocycling simulation decreased the bond strength for both resin cements long-term when the chlorhexidine was not applied before cementation. However, when the root canal was treated with chlorhexidine and the fiber post was cemented with self-adhesive cement, the bond strength increased after 0, 20,000 and 40,000 cycles.

External cervical resorption (ECR) is a sequela of dentoalveolar trauma that may cause functional, esthetic, and psychologic alterations. The aim of this study was to report a successful multidisciplinary treatment approach performed in a 12-year-old patient who presented with posttraumatic ECR associated with extensive opened cavity, pulp necrosis, and periapical lesion of tooth number 9, with an initial unfavorable prognosis. Crown lengthening was done to enable restoration of vestibular surface with resin composite, forming a barrier that allowed endodontic treatment. Afterwards, a prefabricated fiberglass post was cemented and esthetic restoration was performed using the adhesive technique and direct composite veneer. Reconstructive periodontal surgery was performed to correct irregular gingival contour. After treatment and successive follow-up sessions, it was concluded that although the tooth had been indicated for extraction, low invasive direct techniques were effective to recover function and esthetics and to maintain the tooth in the oral cavity.

Introduction: The extension of fiber post cementation often does not seem to influence the fracture resistance of restorations. This study evaluated the effects of cementation depths on the retention of fiber posts submitted to artificial aging., Methods: One hundred and sixty bovine incisors were selected to assess post retention. Following endodontic treatment, the canals were flared with diamonds burs. Postholes were prepared in lengths of 5 or 10 mm, after which fiber posts were relined with composite resin and luted with RelyX ARC or RelyX Unicem. The samples were then submitted to thermal and/or mechanical cycling before testing their pullout bond strengths. Absence of cycling was used as a control. The results of each cement were submitted to two-way and post hoc Tukey tests (α=0.05)., Results: Independent of the aging protocol, a depth of 10 mm showed higher pullout bond strength than did 5 mm, except for RelyX Unicem without cycling. For RelyX ARC, thermomechanical cycling resulted in lower values than in the absence of cycling. Mechanical cycling alone promoted the highest bond strength when the posts were luted with RelyX Unicem., Conclusion: The effect of artificial aging on the pullout bond strength is dependent on the type of material and the depth.

The five cases presented here describe a conservative treatment procedure for complicated crown-root fractures of molars with extensive loss of tooth structure. After the mobile crown-root fragments were extracted, the remaining crowns were restored at the juxtagingival level. The follow-up time ranged from two years, seven months, to four years. At the follow-up examinations, all of the teeth were asymptomatic and had healthy clinical appearances. There was no evidence of pockets related to fractures. The results of these cases show that complete periodontal healing is possible with conservative treatment of complicated crown-root fracture of molars.

Purpose: To investigate the bond of endodontic post materials, with and without grit blasting, to a resin composite cement and a core material using push-out bond strength tests., Materials and Methods: Fiber-reinforced composite (FRC) posts containing carbon (C) or glass (A) fiber and a steel (S) post were cemented into cylinders of polymerized restorative composite without surface treatment (as controls) and after grit blasting for 8, 16, and 32 seconds. Additional steel post samples were sputter-coated with gold before cementation to prevent chemical interaction with the cement. Cylindrical composite cores were bonded to other samples. After sectioning into discs, bond strengths were determined using push-out testing. Profilometry and electron microscopy were used to assess the effect of grit blasting on surface topography., Results: Mean (standard deviation) bond strength values (MPa) for untreated posts to resin cement were 8.41 (2.80) for C, 9.61(1.88) for A, and 19.90 (3.61) for S. Prolonged grit blasting increased bond strength for FRC posts but produced only a minimal increase for S. After 32 seconds, mean values were 20.65 (4.91) for C, 20.41 (2.93) for A, and 22.97 (2.87) for S. Gold-coated steel samples produced the lowest bond strength value, 7.84 (1.40). Mean bond strengths for untreated posts bonded to composite cores were 6.19 (0.95) for C, 13.22 (1.61) for A, and 8.82 (1.18) for S, and after 32 seconds of grit blasting the values were 17.30 (2.02) for C, 26.47 (3.09) for A, and 20.61 (2.67) for S. FRC materials recorded higher roughness values before and after grit blasting than S. With prolonged grit blasting, roughness increased for A and C, but not for S., Conclusions: There was no evidence of significant bonding to untreated FRC posts, but significant bonding occurred between untreated steel posts and the resin cement. Increases in the roughness of FRC samples were material dependent and roughening significantly increased bond strength values (p<0.05). Surface roughening of the tested FRC posts is required for effective bonding.

Purpose: To compare the microhardness of several dual-cure, self-adhesive resin cements used to lute fiber posts at 24 hours and seven days after cementation., Methods: Bovine incisors were selected to lute 15 fiber posts that were 12 mm long (FRC Postec Plus size 3, Ivoclar-Vivadent). Five resin cements were tested: Multilink Automix (Ivoclar-Vivadent), without light-curing, and the self-adhesive resin cements Maxcem Elite (Kerr), RelyX Unicem (3M ESPE), G-Cem (GC), and Smartcem 2 (Dentsply), which were light-cured for 40 seconds (LED Bluephase, Ivoclar-Vivadent). Each root was embedded in chemically cured acrylic resin and stored at 37°C for 24 hours. The roots were transversally sectioned into nine specimens that were each 1 mm thick, with three specimens corresponding to each root third. Indentations (100g, 30 seconds) were performed on each section in the resin cement, at 24 hours and seven days after cementation, using a Vickers digital microdurometer (Buehler). Data were analyzed by two-way analysis of variance, Student-Newman-Keuls test, and paired t-test (p<0.05)., Results: A significant influence was found (p<0.05) for the resin cement evaluated, the root third, and their interactions on microhardness values at 24 hours and seven days after post cementation. RelyX Unicem and G-Cem exhibited the highest microhardness values, whereas Multilink Automix presented the lowest. All resin cements suffered a decrease in microhardness according to root canal depth, with the exception of G-Cem and Multilink Automix at 24 hours and Smartcem 2 after seven days. After seven days, the evaluated resin cements showed a significant increase in microhardness values, with the exception of Maxcem Elite and Smartcem 2 at the coronal third., Conclusions: Microhardness of the self-adhesive resin cements when used to lute fiber posts was material-dependent and higher values were obtained in the coronal third, revealing their sensitivity to light irradiation. More information regarding the polymerization reaction of these cements is warranted. According to the current results, microhardness values were significantly higher one week after post luting.

The aim of this study was to investigate the effect of thermomechanical loading (TML) on the bond strength of fiber posts luted with three different resin cements. Sixty-six extracted human anterior teeth were endodontically treated and restored with fiber posts (RelyX Fiber Posts, 3M ESPE) using three commercially available resin cements and three corresponding core build-up materials (n=22 each): Panavia F 2.0/Clearfil DC Core Automix (Kuraray), Variolink II/Multicore Flow (Ivoclar Vivadent), and RelyX Unicem/Filtek Z250 (3M ESPE). Twelve specimens of each group received all-ceramic crowns and were subjected to TML. The other 10 specimens were stored in saline solution for 24 hours. The roots were sectioned and bond strength was measured using a push-out test. Adhesive interfaces of two specimens of each group subjected to TML were analyzed using field emission scanning electron microscopy (FESEM). Bond strengths of fiber posts were significantly affected by the type of resin cement (p<0.0005) and TML (p<0.0005; two-way analysis of variance). TML significantly reduced bond strengths for all materials ((6.0 (6.2) MPa)) compared with initial bond strengths ((14.9 (10.4) MPa)). RelyX Unicem resulted in significantly higher bond strengths before ((18.3 (10.3) MPa)) and after TML ((9.8 (7.5) MPa)) compared with the other materials (p<0.0005; Tukey HSD). Using FESEM, Variolink II and Panavia F demonstrated a hybrid layer partly detached from the underlying resin cement, whereas no hybrid layer was observed for RelyX Unicem. The decrease in bond strength after TML suggests that retention of fiber posts may be reduced after clinical function. Therefore, endodontically treated teeth that are restored using fiber posts may benefit from additional reinforcement via coronal restorations using adequate ferrules and/or adhesive techniques.

Objectives: This study evaluated the bond strength of luting systems for bonding glass fiber posts to root canal dentin. The hypothesis tested was that there are no differences in bond strength of glass fiber posts luted with different cement systems., Methods: Forty bovine incisors were randomly assigned to five different resin cement groups (n=8). After endodontic treatment and crown removal, translucent glass fiber posts were bonded into the root canal using five different luting protocols (self-cured cement and etch-and-rinse adhesive system; dual-cured cement and etch-and-rinse adhesive system; self-cured cement and self-etch adhesive system; dual-cured cement and self-etch adhesive system; and dual-cured self-adhesive cement). Push-out bond strength was evaluated at three different radicular levels: cervical, middle, and apical. The interface between resinous cement and the post was observed using a stereoscopic microscope., Results: Analysis of variance showed a statistically significant difference among the cements (p<0.05) and the root canal thirds (p<0.05). The self-adhesive resinous cement had lower values of retention., Conclusions: The resin cements used with etch-and-rinse and self-etch adhesive systems seem to be adequate for glass fiber post cementation.

Objective: The load capability of post-restored endodontically treated teeth (ETT) can be determined at different restorative stages. It was the aim of this study to compare the load capability of ETT at these stages., Materials and Methods: Maxillary central incisors were divided into 4 groups (n=10) and endodontically treated. Specimens were restored with: (I) only glass fiber posts (GFP); (II) GFP and composite build-up with 2 mm ferrule; (III and IV) with additional adhesively luted all-ceramic crowns. Group (I) to (III) were statically loaded, and group (IV) was exposed to thermomechanical loading (TML) and subsequent static loading., Results: The lowest median load level of 73 N was determined for group (I). The maximum median load value of 331 N was found for group (III). The comparison of Fmax [N] of group (I), (II) and (III) revealed significant differences between the groups (p<0.001). The specimens of group (IV) failed at significantly lower load values (p<0.005) as similarly restored specimens of group (III) which were only statically loaded. The stage of restoration and TML loading prior to static loading had a significant impact on fracture patterns (p=0.006)., Conclusion: Every additional restorative step torwards a final crown-restored ETT significantly increased the load capability. TML prior to load-to-fracture testing of the complete restorative complex, ie. post, core and crown, significantly decreased maximum load capability.

The current study evaluated the influence of two endodontic post systems and the elastic modulus and film thickness of resin cement on stress distribution in a maxillary central incisor (MCI) restored with direct resin composite using finite element analysis (FEA). A three-dimensional model of an MCI with a coronary fracture and supporting structures was performed. A static chewing pressure of 2.16 N/mm2 was applied to two areas on the palatal surface of the composite restoration. Zirconia ceramic (ZC) and glass fiber (GF) posts were considered. The stress distribution was analyzed in the post, dentin and cement layer when ZC and GF posts were fixed to the root canals using resin cements of different elastic moduli (7.0 and 18.6 GPa) and different layer thicknesses (70 and 200 microm). The different post materials presented a significant influence on stress distribution with lesser stress concentration when using the GF post. The higher elastic modulus cement created higher stress levels within itself. The cement thicknesses did not present significant changes.

This study compared the bond strengths of fiber-reinforced composite (FRC) posts luted into oversized dowel spaces with FRC posts luted into precisely fitting dowel spaces using five different resin cements or build-up composites. The hypotheses examined were that bond strength does not present vast variations according to the width of the gap between the root canal and post and that bond strength increases for FRC posts luted with build-up composites compared with FRC posts luted with resin cements. Dowel space preparations (ER post-restoring system, 12 mm in length) were performed on 100 human anterior teeth up to ISO 90 and ISO 110 of 50 roots each. FRC posts, all ISO size 90, were inserted into the precisely fitting as well as into the oversized dowel spaces (n = 10) using five composite materials (Calibra, Multicore Flow, Rely X Unicem; resin cements and Build-It, Rebilda DC; build-up composites). The manufacturers' instructions of the composite materials were strictly followed except for Rebilda DC, which was used with Adhese for dentin bonding. Following water storage (37 degrees C, 24 hours) and thermocycling (5000 cycles, 5 degrees C-55 degrees C, 30 seconds) tensile strength testing was performed and fracture modes were assessed using SEM. Data were analyzed statistically (one-way and two-way ANOVA, Bonferroni/Dunn correction, alpha < 0.05). The retentive bond strengths of FRC posts in oversized dowel spaces decreased significantly for all luting composites except for Rebilda DC, compared with the respective groups with precise fitting (p < 0.011). Yet, the bond strengths of RelyX Unicem (454 N +/- 64 N), Build-It (422 N +/- 43 N) and Calibra (408 N +/- 50 N) showed significantly higher values for the precisely fitting posts than Rebilda DC (267 N +/- 54 N). RelyX Unicem revealed significantly higher values than Multicore Flow (296 N +/- 73 N). The bond strengths of FRC posts in oversized dowel spaces varied from 301 N +/- 78 N for Build-It to 152 N +/- 37 N for Calibra. The values of Build-It were significantly higher compared with Calibra, Multicore Flow (180 N +/- 47 N) and Rebilda DC (186 N +/- 52 N), as well as those of RelyX Unicem (256 N +/- 115 N) were significantly higher than Calibra. Fracture modes were shown to be mainly adhesive at the post surface or cohesive for precisely fitting posts and to occur between post and composite except for RelyX Unicem with cohesive fractures for the oversized dowel spaces. The build-up composite Build-It showed superior bond strengths in oversized canals, which were still not as high as those of posts in precisely fitting dowel spaces using common resin cements.

This literature review summarizes the research on fiber post surface treatments and provides information related to their benefit in enhancing bond strength to composites, based on the results of original scientific full papers from peer-reviewed journals listed in Pub Med. The search was conducted using the terms "fiber post," "surface treatment," "surface conditioning," "etching" and "sandblasting." A consistent number of in vitro studies that investigated the surface treatment of fiber posts in an attempt to improve bond strength have been published to date. Their results have been summarized in the following categories: chemical treatments and micromechanical treatments of fiber post surfaces (or a combination of both principles). The majority of available literature data is based on studies that investigated different "chairside" post superficial treatments. According to the in vitro results, surface conditioning improves fiber post bonding properties, and the bond strength of pre-treated fiber posts to restorative materials is satisfactory. Long-term clinical studies are needed prior to making a general recommendation for their use.

Objectives: The transmission of light through translucent posts was observed, and the microhardness of light-cured cement used to secure these posts was evaluated at different depths., Methods: Fifteen single-rooted standard bovine teeth, 16 mm in size, were used. The root canals were prepared using #3 drills Light-Post (five teeth) and Aestheti Post (five teeth) systems (BISCO), with a working-length of 12 mm. In five teeth, translucent posts were cemented (Light-Post #2), while another five teeth received opaque posts (Aestheti Post #2). The roots were painted with black nail varnish to prevent the passage of light through the lateral walls of the roots. The root canals of all the specimens were treated with the All-Bond 2 adhesive system (BISCO) and cemented with light-cured cement (Enforce, Dentsply). All the roots were transversally cut to obtain six specimens 1.5 mm thick. Every two sections corresponded to a specific region of the root (cervical, middle, apical), making it possible to observe the cement microhardness at different levels. The groups (n = 10) were defined as: GI: translucent post (TP)/cervical region; G2: TP/middle region; G3: TP/apical region; G4: Opaque post (OP)/cervical region; G5: OP/middle region; G6: PO/apical region. Five root canals were only filled with cement for use as a control (G7). Then, Vickers microhardness analyses were performed., Results: In G3, G5 and G6, the cement was not sufficiently hard to allow for microhardness analysis. When submitted to the ANOVA test, G1 (35.07), G2 (24.28) and G4 (28.64) presented no statistical differences. When the previous groups were compared to G7 (51.00) using the Kruskal-Wallis test, a statistical difference was found., Conclusion: Translucent posts allow cement polymerization up to the middle portion of the root.

Aims: This work studied how prefabricated intraradicular post material affects the mechanical performance of restored teeth. The effect of using two different materials (glass fiber and stainless steel) with significantly different elastic moduli was studied., Methods: A combined theoretical and experimental method was used: first, an experimental fracture strength test was performed on 60 extracted human maxillary central incisors. The teeth were decoronated, treated endodontically and restored, 30 with glass fiber posts and 30 with stainless steel posts. The data were recorded and the results compared using an ANOVA test. Then, the finite element technique was used to develop a model of the restored tooth. For both post systems, the model allowed for the study of stress distribution patterns on the restored tooth under external loads., Results: For teeth restored with stainless steel posts, a significantly lower failure load was found, as compared with those teeth restored with glass fiber posts (520 N versus 803 N). The estimated distributions confirmed a worse mechanical performance on teeth restored using stainless steel posts, with a high stress concentration due to the significant difference between the elastic moduli of the steel and the surrounding materials., Conclusion: Within the limitations of this study, post systems, where the elastic modulus of the post is similar to that of dentin and core, have a better biomechanical performance.

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).

Clinical studies have shown that endodontically treated teeth restored with short posts or deficient ferrules show a high failure risk. This study. evaluated the influence of fatigue loading on the quality of the cement layer between prefabricated quartz coated carbon fiber posts with restricted length and the root canal wall in maxillary pre-molars. Two adhesive resin composite cements, chemical-cured Panavia 21 (Group 1) and dual-cured RelyX-ARC (Group 2), and one resin-modified glass-ionomer cement, chemical-cured RelyX (Group 3), delta were selected for this study. 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 cemento-enamel junction (CEJ). Following endodontic treatment, a post-and-core restoration with 6-mm post length was prepared for each tooth. The posts were directly cemented into the root canal and, after applying an adhesive (Clearfil Photo Bond), they were built up with a core build-up composite (Clearfil Photo Core). 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 were used as the control. Three parallel, transverse root sections, 1.5-mm thick, were cut from each specimen at the apical, medial and coronal location. These sections were examined by Scanning Electron Microscopy (SEM) to evaluate the integrity of the cement layer, while the retention strength of the cemented post sections was determined with the push-out test. The multivariate results of MANOVA showed that the condition main effect (fatigue or control) was not significant (p=0.059); the two other main effects, type of cement and section location, were significant (p=0.001 and p=0.008). For both the push-out strength and SEM evaluation of the cement layer integrity, the results significantly improved from RelyX to RelyX-ARC to Panavia 21 and also from apical to coronal.

Resin posts are used more often than metal posts, as they are esthetically compatible and less damaging to remaining tooth structure. Many resin post systems are available, where a light transmitting post is used to build up the composite in layers. An easier and economical alternative method, a custom-made resin post, is described.

This in vitro study evaluated the effect of various surface treatments of prefabricated posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White) and zirconia (Cerapost) on the bonding of two resin cements: ParaPost Cement and Panavia F by a diametral tensile strength (DTS) test. The posts received surface treatments in three categories: 1) roughening by sandblasting and hydrofluoric acid etching; 2) application of primer by coating with Alloy Primer, Metalprimer II and Silane and 3) a combination treatment in the form of roughening (sandblasting or etching) supplemented by the application of a primer or in the form of the Cojet system. After surface treatment, the post was embedded in a cylinder of resin cement (diameter = 4.0 mm, height = 4.0 mm). The surface-treated post was centered in the resin cement-filled mold with the aid of fixation apparatus. Fifteen minutes from the start of mixing the resin cement, the specimen was freed from the mold and stored in water at 37 degrees C for seven days. Following water storage, the specimen was wet-ground to a final length of approximately 3 mm. The DTS of specimens was determined in a Universal Testing Machine. The bonding of resin cement to titanium alloy posts was increased by several surface treatments of the post. However, coating with primers as sole treatment had no effect on bonding. With the DTS method applied, none of the surface treatments had an effect on the bonding to glass fiber posts. The bonding of both resin cements to zirconia posts was improved by Cojet treatment, while sandblasting, followed by silane application, improved bonding of Panavia F.

This in vitro study generated data on the quality of marginal adaptation, fracture resistance and retention of several indirect adhesive composite configurations on root-treated premolars before and after a long-term fatigue test and compared these results to a control group of adhesive onlays on "vital" teeth. Six root-treated extracted human premolars per group, with four different restorative configurations with and without adhesive fiber posts, were evaluated. Another group of six premolars, "revitalized" by using diluted horse serum to simulate pulpal fluid and restored with adhesive composite onlays, served as the control. Marginal adaptation before and after long-term occlusal loading (1,200,000 occlusal loading cycles at max 49 N) was assessed by using the replica technique and quantitative evaluation in SEM at 200x magnification. The number of lost restorations was recorded after loading. Fracture resistance and fracture patterns were evaluated by using a universal-testing machine on the fatigued samples. No significant differences (p > 0.05) between groups were detected before and after loading for the percentage of "continuous margin" at the total marginal length. Loading had a significant (p < 0.05) effect on the percentage of "continuous margin" for the total marginal length of two groups only. No significant difference (p > 0.05) for fracture resistance was detected and no lost restorations were observed. The results suggest that for both the less decayed and the more significantly decayed devital teeth, the minimally invasive adhesive restorative approach is promising.

This study tested the tensile dislodgment forces of two experimental post designs that are threaded 7 mm into the most coronal aspect of the root. Experimental post systems ParaPost XT-7 (XT-7), and ParaPost XT-10 (XT-10) were compared to the Flexi-Post (FP) and to the Standard ParaPost (SP). The XT-7 prototype post measured 7 mm in length, while all other post systems were 10 mm. The XT-7 and the FP are active post systems that are threaded throughout their entire length. The SP is a passive serrated post system, and the XT-10 is a combination active/passive design that has a 7 mm coronal thread with a passive serrated apical end. All systems tested were titanium alloy except the SP system, which was stainless steel. The purpose of this study was to compare an active and a passive post design to the experimental designs of the XT-7 active post and the combined active/passive design of the XT-10. This study clearly demonstrated highest retention for the active post system, least retention for the passive post, with an intermediate retentiveness for the combined design.

The main purpose of this study was to assess the retention of Paraposts cemented with dentin-bonded resin cements in single-rooted teeth with elliptical canals. Forty-two mandibular premolars and canines were used in this study. The crowns of these teeth were removed 1 mm above the cementoenamel junction and the root canals instrumented to a depth of 8 mm to receive size 5 Paraposts. Prepared teeth were divided into six equal groups. Each group was assigned to a different cementation system at random. The six cementation systems used were: Fleck's Cement, Universal Post Cementation Kit, Prisma Universal Bond 3/Biomer, Scotchbond 2/Resiment, All-Bond 2/All-Bond C & B Cement, and Scotchbond Multi-Purpose/Resiment. Following post cementation, the teeth were stored in water at 37 degrees C for 24 hours, after which the posts were subjected to uniaxial tensile force on a testing machine until post separation occurred. Paraposts cemented with Prisma Universal Bone 3/Biomer or with Scotchbond Multi-Purpose/Resiment had significantly greater separation forces than posts cemented with any of the other cementation systems. Adhesive failure of the posts occurred in all of the specimens of the resin cement groups, whereas cohesive failure of the cement occurred in the majority of the specimens of the zinc phosphate cement group. The effects of thermocycling and post length (5 mm versus 8 mm) on the retention of Paraposts cemented with dentin-bonded resin cements were also investigated. Neither thermocycling nor post length had a significant effect on post separation force.

In this study, the depth of cure of composite resins cured within simulated root canals by means of light-transmitting plastic posts was compared to that achieved by the conventional light-curing method. Six sizes of posts with diameters of 1.05 mm, 1.20 mm, 1.35 mm, 1.50 mm, 1.65 mm, and 1.80 mm were investigated. In general, the larger the post diameter, the greater was the depth of cure. There were significant differences in the depth of cure between the control and all sizes of posts investigated. There were also significant differences between the various post diameters except for the 1.35 mm and 1.50 mm diameter posts. It was possible to achieve a depth of cure exceeding 11 mm using these light-transmitting posts.

The stress generated by five prefabricated endodontic dowel designs was evaluated using a two-dimensional photoelastic model. Cemented posts caused the least stress. Of the threaded posts, Flexi-post and Radix Anker produced the least stress; Kurer Crown Anchor produced the most.