Fiber Posts Research Articles

Effectiveness of different fiber post removal techniques and their influence on dentinal microcrack formation

ObjectivesThe aim of this study was to evaluate the effectiveness of different fiber post removal techniques and to correlate dentinal loss with microcrack formation.Materials and methodsForty-five extracted single-rooted teeth were root canal treated and fiber posts were adhesively luted. Specimens were divided into three groups (n = 15) according to the removal technique: long-shaft round bur (EndoTracer #08, Komet, Lemgo, Germany), SonicFlex Endo (KaVo, Biberach, Germany), DT Post Removal Kit (VDW, Munich, Germany). Roots were scanned before post cementation and after post removal using micro-computed tomography. Dentin loss, residual luting material, working time, and the induction of microcracks were assessed. Statistical analysis was performed by using multiple contrast tests (max-t tests, α = 0.05). Correlations between parameters dentin loss/new microcracks and dentin loss/residual material were calculated using Kendall’s tau.ResultsPost removal with SonicFlex Endo resulted in the highest amount of removed dentin with significant differences to the round bur and the DT Post Removal Kit. No technique was found to completely remove the post and luting material. All techniques induced microcracks with the DT Post Removal Kit presenting the highest number of new defects. No correlation between dentin loss and new microcracks was observed. Deviations from the original root canal occurred in all groups, but no perforation was observed.ConclusionsAll techniques resulted in dentin loss, residual luting material, and the formation of microcracks. However, no correlation between dentin loss and the induction of microcracks was observed.Clinical relevanceAs all techniques resulted in microcrack formation and dentin loss, this study emphasizes the risk of iatrogenic damage due to post removal procedures.

Effect of intracanal diode laser irradiation on fracture resistance of roots restored with CAD/CAM posts

Aim: To evaluate the fracture resistance of roots restored with CAD/CAM-fabricated posts, receiving or not intracanal laser treatment, compared with glass fiber posts under mechanical cycling. Methods: Twenty-seven endodontically treated, single-rooted teeth were divided into 3 groups: group 1 (control), prefabricated glass fiber posts relined with resin composite; group 2, CAD/CAM-fabricated intraradicular posts using Resin Nano Ceramic (RNC) blocks; and group 3, CAD/CAM-fabricated intraradicular posts using RNC blocks in canals irradiated with a 940-nm diode laser (100 mJ, 300-um optic fiber, coronal-apical and apical-coronal helical movements, speed of 2 mm/second, 4 times each canal). After cementation of the coping, cyclic loading was applied at an angle of 135° to the long axis of the root, with a pulse load of 130 N, frequency of 2.2 Hz, and 150,000 pulses on the crown at a point located 2 mm below the incisal edge on the lingual aspect of the specimen. Every 50,000 cycles, the specimens were evaluated for root fracture occurring below or above the simulated bone crest. Results were analyzed by one-way ANOVA followed by Tukey’s test (p<0.05). Results: Group 1 was the least resistant, while groups 2 and 3 were the most resistant. Group 1 differed significantly from groups 2 and 3 (p<0.01), but there was no difference between groups 2 and 3 (p<0.01). Conclusion: Treatment of the intracanal surface with diode laser had no influence on fracture resistance of roots restored with CAD/CAM-fabricated posts, but a longer cycling time is required to evaluate the real benefits of diode laser irradiation.

Clinical Performance of Cast Metal and Fiber Post Retained Restorations in Endodontically Treated Teeth: A Systematic Review and Meta-Analysis

Purpose: The purpose of this systematic review was to assess the available literature to evaluate the clinical performance of different post systems for the rehabilitation of endodontically treated teeth (ETT).
 Clinical Significance: The loss of structural integrity of endodontically treated teeth usually requires the use of intra-radicular posts for the retention of the final restoration. The recent literature has reported controversial results regarding the clinical performance of different systems.
 Material and Methods: An electronic search restricted to the English language was performed up to May 31, 2020. Articles were selected if they met the following criteria: cohort studies and randomized clinical trials comparing the failure rate incidence between fiber and cast metal post, with a mean follow-up of 3 years.
 Results: 24 studies (14 cohort studies and 10 RCTs) published between 2000 and 2018 were included in this review. For cast metal posts, 210 cases were classified as failures (17.07%), and for fiber posts, 423 were classified as failures (10.6%). An unpaired t-test revealed that cast metal and fiber post values were not significantly different (p = 0.58) with the difference between means of 5.00 with 95% confidence of interval (-13.38 to 23.39). Four studies that presented cast metal and fiber posts groups were combined in the meta-analysis. There was no significant difference in the general failure analysis (risk ratio of 0.59 [95% CI: 0.30 to 1.18]; p = 0.13).
 Conclusions: Based on the present analysis results, the clinical performance of ETT restored with either cast metal- or fiber post-retained restorations presented similar results.

Pull-out bond strength of fiber post luted with two types of resin luting cements using different light curing units.

The aim of this study was to evaluate the pull-out bond strength of fiber post when cemented with a self-adhesive dual-cured resin luting cement and a conventional light-cured resin luting cement. In addition, the influence of a light-emitting diode (LED) and halogen (QTH) curing lights on the pull-out bond strength was assessed. A total of 40 extracted human teeth were selected. Post-space preparation of 10 mm was done and two types of resin cement i.e. RelyX Unicem (RXU) and variolink esthetic LC (VLE) were used for cementation of a translucent RelyX fiber post. Light activation for 60 s was done with LED and QTH curing units. The pull-out test was performed parallel to the long axis of the tooth and the post at a crosshead speed of 1 mm/min using a universal testing machine. The load required to dislodge each post was recorded in Newton (N). Statistical analysis was done and a value of P < 0.05 was considered statistically significant. The RXU showed a mean (SD) pull-out bond strength of 203.5N (47.1) and 207.3N (31.3) when light activated with LED and QTH curing lights, respectively. For VLE, the mean pull-out bond strength was 78.9N (21.5) and 87.7N (30.7), when light activated with LED and QTH curing lights, respectively. Moreover, LED and QTH curing lights did not influence the pull-out bond strength for both the test materials. It is concluded that a dual-cured resin luting cement should be used for the cementation of fiber post. Further research is required to understand the light transmission of translucent fiber posts.

Fatigue performance of endodontically treated premolars restored with direct and indirect cuspal coverage restorations utilizing fiber-reinforced cores

ObjectivesThe aim of this in vitro study was to investigate the fatigue survival and fracture behavior of endodontically treated (ET) premolars restored with different types of post-core and cuspal coverage restorations.Materials and methodsMOD cavities were prepared on 108 extracted maxillary premolars. During the endodontic treatment, all teeth were instrumented with rotary files (ProTaper Universal) to the same apical enlargement (F2) and were obturated with a matched single cone obturation. After the endodontic procedure, the cavities were restored with different post-core and overlay restorations (n = 12/group). Three groups (A1–A3) were restored with either conventional composite core (PFC; control) or flowable short-fiber-reinforced composite (SFRC) core with/without custom-made fiber posts and without overlays. Six groups had similar post-core foundations as described above but with either direct PFC (B1–B3) or indirect CAD/CAM (C1–C3) overlays. Fatigue survival was tested for all restorations using a cyclic loading machine until fracture occurred or 50,000 cycles were completed. Kaplan-Meyer survival analysis was conducted, followed by pairwise post hoc comparisons.ResultsNone of the restored teeth survived all 50,000. Application of flowable SFRC as luting-core material with fiber post and CAD/CAD overlays (Group C3) showed superior performance regarding fatigue survival (p < 0.05) to all the other groups. Flowable SFRC with fiber post and direct overlay (Group B3) showed superior survival compared to all other direct techniques (p < 0.05), except for the same post-core foundation but without cuspal coverage (Group A3).ConclusionsCustom-made fiber post and SFRC as post luting core material with or without cuspal coverage performed well in terms of fatigue resistance and survival when used for the restoration of ET premolars.Clinical relevanceThe fatigue survival of direct and indirect cuspal coverage restorations in ET MOD premolars is highly dependent on whether the core build-up is fiber-reinforced or not. The combination of short and long fibers in the form of individualized post-cores seems to offer a favorable solution in this situation.

A Novel Method for Managing Flared Root Canal with Anatomic Post and Core: A Case Report

The compromised tooth structure after endodontic treatment necessitates the use of post and core for structural durability. Management of the flared root canal is still a tough obstacle for the clinicians. Reinforcing the root canal space with the customised anatomic post thus regains the lost structure within the canal and aids in establishing a great strength and stability to the tooth structure. The report of this case scenario aims on clinical technique of fabricating anatomic post with glass - fibre posts and composite resin on a central and lateral incisor.

Effect of Cervical Lesions on Fracture Resistance and Failure Mode of Maxillary Central Incisors Restored with Fiber Posts and Complete Crowns.

To investigate the effect of a cervical cavity extending 1 mm apical to the cemento-enamel junction (CEJ) on fracture resistance and failure mode of maxillary central incisors that have been treated endodontically, present with complete and incomplete ferrules, and are restored with and without a fiber post. 50 intact human maxillary central incisors were divided into five groups (n=10): CG (control group) 6-mm fer-rule height, no cervical cavity, and without post; (CO) 6-mm ferrule height without post, with a cervical cavity (access to root canal and cervical cavity restored with composite resin), cervical cavity; and post with ferrule heights of 1 mm (CP1), 2 mm (CP2), and 6 mm (CP6) restored with fiberglass post and composite resin core. After complete metal crowns were cemented on all specimens, they were subjected to thermal cycling (6000 cycles, 5°C/55°C), followed by immediate testing of fracture resistance. After failure, the specimens were sectioned buccolingually to evaluate and identify the mode of failure. The data were analyzed with an analysis of variance (ANOVA) and the Student-Newman-Keuls multiple comparison tests (α =0.05). A 1-mm ferrule height (CP1) fracture resistance was significantly lower (531±125 N) compared to the 6-mm ferrule height (CP6) (769±175 N) (p<0.05). With respect to the groups with similar residual dentin, with and without a cervical cavity, CG (667±119 N) and CO (668±119 N), the presence of a post (CP6) increased the resistance to fracture, although no statistically significant difference was demonstrated. Partial decementation was observed in all specimens of CG and CP6, in nine of CP1 and CP2, and in three in CO. Root fractures occurred in 23 specimens. The root surface was exposed 2 mm below the CEJ to simulate bone level. Propagation of subosseous cracks occurred in four specimens in CG and CP2, in seven specimens in CP6, in two specimens in CP1, and in six specimens in CO. All were considered catastrophic failures. Within the limitations of this study it is suggested that, when restoring an endodontically treated maxillary central incisor that has a cervical lesion and needs to be restored with a complete crown, a fiber post is cemented to improve fracture resistance.

The effect of etching techniques on cement penetration into dentinal tubules on fiber post cementation

ObjectiveA combination of self-etch and additional etch techniques as pre-cementation procedures for fiber post restoration was reported able to increase the bonding of adhesive material. This research aimed to determine the effects of different etching techniques on resin cement penetration into dentinal tubules. Materials and methodsThirty-two endodontic treated premolars were prepared for 10 mm fiber posts and were divided into two groups (n = 16). Group one was treated with self-etch only, and the second was treated with a combination of self-etch and additional etching. The fiber posts were cemented using fluorescent rhodamine B 0.1%-colored resin cement. The samples were cut to a 2 mm thickness in the middle third of the root and were evaluated with confocal laser scanning microscopy (CLSM). Statistical analysis measurements were analyzed by an independent t-test and Pearson correlation test. ResultsThere were statistically different in densities hybrid layer and resin tag penetration lengths. Statistically strong linear positive correlations between the hybrid layer density and resin tag penetration length in both groups were also observed. Hybrid layer density (9.68 μm), resin tag penetration depth (32.51 μm) in the self-etch group with additional etching were higher than in the other group. The Pearson correlation test results between hybrid bond density and resin tag penetration depth in the self-etch treatment group showed a value of r = 0.634 and p-value = 0.008 and in the etching group self-treatment with additional etching a value of r = 0.516 and p-value = 0.041 (p ≤ 0.05). ConclusionThere is a statistically significant positive correlation or linear relationship between hybrid bond density and the penetration depth of resin tags in both treatment groups: the thicker the hybrid layer density, the deeper the penetration of the resin tags. This phenomenon may increase mechanical strength regarding stronger binding of resin cement to a tooth’s substrate.

Comparison of the effect of QMix and conventional root canal irrigants on push-out bond strength of fiber post to root dentin.

ObjectivesThis study aimed to assess the effect of application of QMix and common root canal irrigating solutions on the bond strength of fiber post to root dentin.Material and MethodsIn this in‐vitro study, 60 extracted incisor teeth were decoronated such that 15 mm of root length remained. The canals were prepared with ProTaper rotary system to F5 and filled with gutta‐percha and AH26 sealer. Prior to post placement, the teeth were divided into four groups based on the type of final irrigating solution namely saline, 5.25% NaOCl, 2% chlorhexidine, and QMix. The fiber posts were then cemented with Panavia F2 resin cement. The roots were sectioned perpendicular to their longitudinal axis, and four sections with 1 mm thickness were made at the middle and coronal thirds of the roots. The push‐out bond strength of fiber posts was measured by a universal testing machine in megapascals. Data were analyzed by two‐way ANOVA and Tukey's test.ResultsThe maximum and minimum bond strength values were noted in QMix and NaOCl groups in both the middle and coronal third of the root, respectively. But, there was no significant difference between the push‐out bond strength in the middle or coronal third of the root (p = 0.054). Adhesive failure was the most common mode of failure in all groups.ConclusionUse of QMix for post space irrigation does not compromise the bond strength of fiber post to root dentin, and can be used for final rinsing of the post space.

Treatment Modalities for Rehabilitation of Mutilated Primary Anterior Teeth

Early childhood caries commonly affects the primary maxillary anterior teeth, in which extensive post- endodontic rehabilitation has always been a challenge. This is due to the small size of the crown, relatively large pulp chambers, and the age of the child. The remaining inadequate sound tooth structure renders restorations more prone to fractures. Among the available treatment modalities which include extraction of the grossly destructed tooth structure, use of semipermanent crowns and intracanal posts, the posts can be used effectively, to restore the lost function and anatomy. They also enhance the quality of the final coronal restoration by providing additional support for retention. The available methods for intracanal reinforcement for anterior teeth include the metal posts fabricated using orthodontic wires, short composite posts fabricated directed in the primary root canal, prefabricated glass fiber posts and posts utilising polyethylene fibers (Ribbond). Recently certain advanced techniques such as the biologic dentin and zirconia have also come into use. The various advantages and disadvantages for these have been summarised in this review along with the standardised clinical protocol for their placement in the primary root canals. Various in-vivo and in-vitro studies have concluded that the glass-fiber short intracanal posts provide the most suitable esthetics, strength, elastic modulus, and resilience. However, further qualitative research is required to certify it as a standard treatment modality.

Photodynamic therapy and gaseous ozone versus conventional post space treatment methods on the push-out bond strength of fiber posts luting with different resin cements

BackgroundThe aim of this study was to compare the push-out bond strength of fiber posts by using two different resin cement after the treatments of post space with photodynamic therapy, gaseous ozone and conventional disinfection solution. MethodsThe root canal treatments of one hundred maxillary incisors were performed. The roots were randomly distributed into 5 groups (n = 20). NaOCl of 2.5% + EDTA of 17% in group 1, CHX of 2% in group 2, toluidine blue + diode laser as the photodynamic therapy (PDT) in group 3 and ozone in group 4 were applied to the post spaces. Group 5 was washed with distilled water as control group. Each group was divided into two subgroups according to the adhesive types and the posts were bonded by using RelyX and LinkForce. The bond strength was calculated using the push-out test method. Resin tag formations were photographed with SEM. The push-out bond strength was analyzed by ANOVA and Tukey tests (p = .05). ResultsThe PDT group, which showed the highest PBS among the groups bonded with LinkForce at all levels, was significantly higher than Ozone and DW groups (p<.05). NaOCl and ozone treatments provided the highest PBS among the groups bonded with RelyX for all levels and this difference was significant according to the DW group (p < .05). ConclusionPost space treatments improved the bond strength of the fiber post ​​in both types of resin cement.

A novel insertion design of fiber materials for the adhesive reattachment in vertically fractured teeth.

ObjectiveThis ex vivo study aimed to evaluate the strengthening effect of different ferrule and reattachment designs with fiber and adhesive materials on vertically fractured teeth.MethodsNinety extracted single-root premolars were instrumented and divided into nine groups (two control groups and seven experimental groups; n = 10). The negative control (NC) group comprised of intact teeth, while the positive control (PC) group comprised of root canal-treated teeth. The roots of the teeth in the experimental groups were vertically fractured into two equal fragments. The fragments were reattached with one of the followings: 4-methacryloxyethyl trimellitate anhydride/methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin, 4-META/MMA-TBB + quartz fiber post, 4-META/MMA-TBB + glass fiber bundles, 4-META/MMA-TBB + quartz fiber post + 1 mm ferrule, 4-META/MMA-TBB + glass fiber bundles + 1 mm ferrule, 4-META/MMA-TBB + quartz fiber post + 2 mm ferrule, and 4-META/MMA-TBB + glass fiber bundles + 2 mm ferrule. The core build-ups were made with composite resin. The specimens were subjected to compressive loading until failure occurred. Mean load necessary to fracture each sample and the fracture types of these samples were recorded.ResultsThe highest mean fracture load was recorded in the NC group (1,036.7 N), which was not significantly higher than the PC group (989.66 N) (p > 0.05). The roots reattached with quartz fiber post demonstrated significantly less fracture strength (871.9 N) as compared to the other test and control groups (p < 0.05). There was no significant difference between the PC group and reattached fragments with different ferrule designs in terms of fracture resistance (p > 0.05).ConclusionsThe customized fiber bundles may be more suitable for reattachment of vertically fractured teeth than the rigid fiber posts. For reattachment procedures, the ferrule design may be preferred to increase the fracture strength of vertically fractured teeth.

Effect of Different Surface Treatments of Glass Fiber Posts on their Surface Roughness and Flexure Properties

AIM: This study aimed to assess the effect of different surface treatments on the surface roughness and flexure properties of glass fiber posts “GFPs.” MATERIALS AND METHODS: A total of 40 GFPs were divided into four groups (n = 10): GC – no surface treatment (control), GSB – sandblasted, GHF – hydrofluoric acid etched, and GL – Er: YAG laser irradiated. Surface roughness was detected using surface profilometer and the 3-points bending flexural test measured flexural strength and elastic modulus. RESULTS: GSB showed the highest mean roughness followed by GHF, then GL, while GC had lowest roughness mean value. The 3 points bending test results were calculated and recorded, GSB exhibited the highest flexure stress (MPa) compared to GHF and GL. Modulus of elasticity (GPa) showed significant differences between the tested groups, GSB showed the highest modulus of elasticity compared to GHF and GL, while GC showed insignificant differences with all tested groups. CONCLUSION: Different surface treatments postulated in this study showed alternations of GFPs surfaces without jeopardizing the mechanical properties of GFPs.

Could light-curing time, post-space region and cyclic fatigue affect the nanomechanical behavior of a dual-curing cement for fiber post luting?

ObjectiveTo evaluate the effects of curing time, post-space region and cyclic fatigue on the micromechanical properties of a fiber-post luting cement. The null hypotheses were that (1) curing time, (2) fatigue and (3) post-space region does not affect the nanoindentation modulus and hardness of the dual-curing cement. Materials and methods48 premolars were endodontically treated and a class I cavity and 8 mm deep post space was prepared. Fiber posts were luted with a universal, dualized adhesive system and a dual-curing cement following manufacturer's instructions. Specimens were divided into three groups (16 specimens for each group) according to light-curing time (no light-curing, 20 s light-curing and 120 s light-curing), which was performed with a LED lamp at 1000 mW/cm 2. The coronal part of the cavity was restored using a nano-filled resin composite. After 24 h, 8 specimens for each group were randomly extract in order to undergo to fatigue test in wet condition through a chewing simulator, while the other specimens were kept in distilled water as benchmark. All the restored teeth were then sectioned in 1 mm thick slices perpendicularly to the fiber post axis. Specimen slices were classified in coronal and apical to be tested through a nanoindenter. Data were analyzed through Kruskal-Wallis test with a significance level of 1%, in order to evaluate the influence of treatments (i.e., curing time and cyclic loading) on the micromechanical properties of the tested luting cement. ResultsBoth fatigue and curing time significantly influenced nanoindentation modulus and hardness of dual-curing cement (p < 0.01). No significant differences were reported for post space region. A significant interaction was found among the analyzed factors (p < 0.01). Significance120 s light-curing time is recommended in order to achieve optimal mechanical proprieties, independently from post space region and cyclic fatigue. As matter of fact, 120 s light-curing allowed to prevent strain hardening induced by the fatigue simulation.

Effect of types of resin cements on the bond strength of fiber post under simulated dives

Background: Changes in barometric pressure conditions that occur during flying and diving under hyperbaric oxygen conditions were found to influence the retention of dental restorations. Aim: This experimental laboratory study aimed to evaluate the bond strength of glass fiber posts after being cemented with self-adhesive resin cement (RelyX™ Unicem, 3M ESPE) and self-etch adhesive resin cement (RelyX™ Ultimate, 3M ESPE) under normal atmospheric pressure and hyperbaric pressure cycles that simulate diving conditions. Methods: A total of 40 extracted, single-rooted mandibular premolars were treated endodontically and randomly divided into two groups according to the cements used for fiber post cementation. Each group was further randomly divided into two equal subgroups that were subjected to normal atmospheric pressure conditions and a simulated hyperbaric condition in a hyperbaric chamber. The pull-out bond strength of fiber posts was tested using a universal testing machine. Data were analyzed using one-way analysis of variance with the Tukey post-hoc test (p&lt;0.05). Results: At normal atmospheric pressure the mean value of the pull-out bond strength of RelyX Ultimate cement was significantly higher than that of RelyX Unicem cement. At hyperbaric pressure condition no significant difference was found between the mean values of the pull-out bond strength of RelyX Ultimate and RelyX Unicem cement. Conclusion: Hyperbaric pressure cycles demonstrated improved pull-out bond strength of glass fiber posts in RelyX Unicem cement but did not have significant effect on pull-out bond strength in RelyX Ultimate cement. Both resin cements have similar pull-out bond strength of glass fibers post after simulated dives.

Effect of Diode Laser irradiation on the Bond Strength of Fiber Posts after Endodontic Retreatment Using Different Sealers.

Purpose: To investigate the effect of diode laser activated irrigation on bond strength between fiber post and radicular dentin after endodontic retreatment using two different sealers. Materials and Methods: Seventy-two extracted human maxillary central incisors were collected, decoronated, endodontically prepared then divided to three groups (n=24) according to sealer type: GP group: gutta-percha without sealer (control group); AD group: AD sealer; and BC group: Bioceramic sealer. Specimens were endodontically retreated after 30 days using the same sealers. 10 mm deep post spaces were prepared in each specimen. Each group was further sub-divided into three subgroups (n=8) according to post space treatment: irrigated with saline (Control), (EDTA) and (laser and EDTA). One tooth from each group was selected for SEM analysis. Posts were cemented, push out tests were performed. Failure modes were analyzed using a digital microscope. Results: With all dentin pretreatment protocols, AD group recorded the highest bond strength mean value followed by GP and BC group respectively, with significant difference (P 0.05). Predominant failure mode was the mixed type as detected by Chi square test. SEM revealed absence of smear layer and opened dentinal tubules after (laser and EDTA) treatment. Conclusions: laser activated irrigation of root dentin significantly improved the bond strength of fiber post after endodontic retreatment with both sealers.

Fracture Resistance of Titanium and Fiber Dental Posts: A Systematic Review and Meta-Analysis.

The fracture resistance of dental post systems is influenced by the material of the post. The purpose of this systematic review and meta-analysis was to assess if there is a difference in fracture resistance between prefabricated dental titanium posts and fiber posts. An online electronic search was performed using the PubMed, Scopus, and Web of Science databases for in vitro studies published from 2010 to 2020 in English. The retrieved eligible studies that compared the fracture resistance of titanium and fiber posts on human teeth were selected. The pooled standardized mean difference (SMD) with a 95% confidence interval was calculated. In addition, the trial sequential analysis (TSA) was performed to test if the available studies are sufficient to make conclusive evidence. Of the 1165 retrieved studies, 17 studies were included in the qualitative analysis, while 16 studies were included in the quantitative analysis. Because of the high heterogeneity among studies, data from 10 studies were pooled and submitted to TSA. A total of 852 teeth were evaluated for fracture of the posts in 27 independent comparison groups. The pooled effect of the residual studies revealed no significant difference between titanium and fiber posts (SMD = -0.12; 95% CI = -0.30, 0.06; p = 0.20). Results of the TSA revealed no conclusive evidence. The results of the current evidence revealed no significant difference between fiber and titanium posts. The evidence is insufficient, and more standardized in vitro studies are required.

A laboratory study to assess the physical, mechanical, and 3-D structural properties of nano-apatite grafted glass fibre-based endodontic posts.

To fabricate and characterize nano-hydroxyapatite (nHA) grafted and non-grafted glass fibre-based endodontic posts. Experimental glass fibre posts were fabricated using silanized nHA grafted (ex-HA) and non-grafted glass fibre (ex-P) reinforced resins. The structural analysis and morphological patterns were analysed with Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. EverStick® glass fibre posts (eS) were used as a control group. The degree of conversion, flexural strength, and flexural modulus was investigated and the fractured structure was evaluated with a scanning electron microscope. Root canals were prepared in human extracted teeth restored with experimental and control posts. The push-out bond strength was evaluated with radicular dentine at days 7, 30, and 90, and the presence of voids at the interface were measured at day 1, 7, 30, and 90 with micro-computed tomography. The Shapiro-Wilk test and one-way ANOVA post-hoc Tukey's test were performed. The level of significance was set at 0.05. The SEM and FTIR confirmed the presence of a silane-coupling agent on the glass fibres. The ex-HA post had a significantly lower degree of conversion compared to the ex-P post (p=.0008), but a significantly higher conversion than the eS post (p=.0014). The maximum flexural strength value was obtained with the ex-HA post with an insignificant difference (p=.366) compared to ex-P post and a significant difference (p=.029) compared to the eS post. The flexural modulus of ex-HA, ex-P, and eS posts were significantly different (p=.037). Similarly, the ex-HA post had a significantly higher push-out bond strength at days 7 and 30 (p=.037) compared to the ex-P and eS posts. The volume of voids had a nonlinear behaviour amongst the groups with no significant difference between the posts. The fabrication of the experimental posts was successful and the ex-HA post had greater flexural strength and push-out bond strength compared to the ex-P post. The degree of conversion of the ex-HA post was lower than the ex-P and eS posts. The volume of voids of ex-HA and ex-P posts was lower than that of eS posts.

Assessing dentists’ knowledge and experience in restoring endodontically treated teeth using post & cores

ObjectivesThe restoration of endodontically, heavily filled teeth has been a challenge for the dental profession for decades. The aims of this study were to investigate dentists’ experience and knowledge in the use of post & core when restoring endodontically treated teeth. MethodThis was a mixed method study incorporating quantitative and qualitative data collection. An online questionnaire was developed and distributed, comprised of 18 questions. It was calculated that 93 respondents were needed to validate the study of which 60% should meet a minimum knowledge requirement. Results173 respondents completed the questionnaire. 109 (63% (95%CI56%,70%) demonstrated proficient knowledge of post & core restorations. Recent graduates were more likely to follow current guidelines (F = 4.570: P<0.034). As the age of respondent dentists increases the number of posts placed (F = 18.85; p<0.001) and the perceived confidence level increases (Spearman's Rho 0.43: P<0.01). Experience of postgraduate education also positively influenced clinical confidence. ConclusionThe placement of post & cores is influenced by age. Confidence is also influenced by age. More evidence on post usage is required and several questions remain to be answered on what drives decision making and perceived long-term success. Clinical significanceThere is a general acceptance of when a post and core restoration should be used. Clinician experience and age can have an impact on what type of restorations are used. Fibre posts are more commonly used due their accessibility and cost.

Push-out bond strength and failure mode of single adjustable and customized glass fiber posts

PurposeTo evaluate the push-out bond strength (PBS) and failure mode of single adjustable (SAP) and customized (CP) posts cemented to root canal dentin using conventional (RelyX Ultimate) or self-adhesive (RelyX U200) dual-cure resin cements. MethodsHerein, 40 bovine mandibular incisors were divided into four groups (n = 10): SAP cemented with RelyX Ultimate (SAP-UT), SAP cemented with RelyX U200 (SAP-U2), CP cemented with RelyX Ultimate (CP-UT), and CP cemented with RelyX U200 (CP-U2). PBS and failure modes were analyzed. Three-way repeated measures ANOVA test followed by Tukey’s test and Fisher–Freeman–Halton exact test were used for data analysis (α = 5%). ResultsThe PBS values for SAP (p < .05) were higher than those for CP and were not influenced by the root third and resin cement (p > .05). When conventional resin cement was used, the SAP showed significant differences compared to CP (p < .05). When cemented with RelyX Ultimate, a higher prevalence of mixed and adhesive failures for SAP and CP, respectively, was observed (p < .05). For the self-adhesive resin cement, the failures were mostly adhesive (p < .05). ConclusionSAP showed better performance than CP. The root third and resin cements did not influence the PBS. The most prevalent failures were adhesive and mixed.