Fiber Posts Research Articles

Effect of intra-radicular cleaning protocols after post-space preparation on marginal adaptation of a luting agent to root dentin.

To evaluate the effect of intra-radicular cleaning protocols after post-space preparation (PSP) on marginal adaptation of a luting agent to root dentin. Eighty bovine incisors were sectioned transversely to obtain 18-mm-long root sections. The roots were prepared with ProTaper instruments and filled using Tagger's hybrid technique. PSP was performed at a length of 14 mm using #3-5 Largo drills. The roots were distributed into eight groups according to the chelating solution used (17% EDTA or 0.2% Chitosan) and the chelating activation/delivery method employed (conventional needle irrigation [CNI], EndoActivator [EA], XP-Endo Finisher [XPF] or passive ultrasonic irrigation [PUI]). The fiber posts were cemented using self-adhesive resin cement, and the roots were sectioned to obtain three discs from each root third. The dentin discs were observed under an optical microscope at ×40 magnification to assess marginal adaptation. The different protocols were compared considering the frequency of the marginal adaptation scores using the Kruskal-Wallis test, followed by the Dwass-Steel-Critchlow-Fligner test (α = 5%). The use of 17% EDTA resulted in better marginal adaptation (P < 0.001). PUI yielded results that were similar to those for EA (P = 0.949) and superior to those for XPF (P = 0.020). The combination of 17% EDTA + PUI provided a greater number of interfaces without marginal gaps (P < 0.001). The cleaning protocol influenced the marginal adaptation of resin cement to root dentin.

Effect of dentin moisture on the adhesive properties of luting fiber posts using adhesive strategies.

The purpose of this study was to evaluate the effect of dentin moisture (moist and dry) on the bonding of fiber posts to root dentin with different adhesive strategies (etch-and-rinse, self-etch, and self-adhesive). Seventy-two extracted single-rooted human teeth were endodontically treated and divided into six groups (n = 12) according to the moisture of dentin surface and adhesive systems as follows: a) etch-and-rinse/moist, b) etch-and-rinse/dry, c) self-etch/moist, d) self-etch/dry, e) self-adhesive/moist, and 6) self-adhesive/dry. The specimens were sectioned into six slices for push-out bond strength (BS), nanoleakage (NL) by SEM, and Vickers microhardness (VHN) of the resin cement. A universal testing machine (AG-I, Shimadzu Autograph) was used at a crosshead speed of 0.5 mm/min until post extrusion, with a load cell of 50 kg for evaluation of the push-out strength. Data on BS, NL, and VHN were evaluated by two-way ANOVA and Tukey's test (α = 0.05). Dentin moisture as the main factor was not significantly different for the push-out test. However, higher BS values can be observed for the etch-and-rinse group. A lower percentage of NL was found in the dry dentin groups. The moisture pattern was not significant in the hardness values for the pre-etching groups. Additional moisture did not increase the evaluated properties.

A Comparative Evaluation of Fracture Resistance in Endodontically Treated Teeth Reinforced by Novel Hybrid Post and with Various Pre-Fabricated Post Techniques: An In-Vitro Study

Introduction: Teeth with a final post-endodontic restoration cannot support significant structural loss brought on by fracture, caries, big pre-existing restorations, or aggressive cavity preparation. Post and core restoration allows for the restoration of such teeth. Reduced dentine size, moisture, and compromise on supporting structures such the oblique bridge, marginal ridges, and pulp chamber roof result in a reduction in their resistance because of structural loss. Under such circumstances, choosing a good post-endodontic restorative material can be difficult. Materials and Methods: In terms of post-treatment procedures, 40 single-rooted decoronated mandibular premolar teeth were endodontically treated and randomly divided into four groups. As a control, the first group had a composite core but no post; groups two and three had prefabricated metal threaded posts; group four had prefabricated hybrid posts. The posts were affixed using dual-cure resin cement, and the core build-up material was nano composite. Each group's core structure was standardised, and metal crowns of the same size were used to reinforce it. A universal testing machine was used to test every specimen, and the fracture load was tabulated. Statistical analysis used: one way ANOVA analysis Results: The highest failure load was found with prefabricated hybrid post. This group had significantly higher load compared to other post groups. Followed by prefabricated fibre post and prefabricated metal threaded post. Conclusions: Fracture resistance of endodontically treated teeth reinforced with hybrid post showed significant values when compared to that of prefabricated glass fiber posts, prefabricated threaded post and control teeth.

Farklı İrrigasyon Solüsyonlarının Fiber Postların Kök Kanal Dentinine Bağlanma Mukavemeti ve Dentin Mikrosertliği Üzerindeki Etkisi: Metadolojik Çalışma

Objective: This study aimed to compare the effect of sodium hypochlorite (NaOCl), chlorhexidine (CHX), ethylene daimine tetra acetic acid (EDTA) and etidronic acid (HEBP) solutions and their combinations on a push-out bond strength of fiber posts to root canal dentin and on root dentin microhardness. Material and Methods: Sixty human maxillary central incisors were sectioned below the cementoenamel junction, the roots were endodontically treated and were divided into 6 groups (n=10) according to the final irrigation protocol: (1) Distilled water, (2) CHX, (3) HEBP-NaOCl combination, (4) HEBP, (5) 2.5 % NaOCl, (6) 17% EDTA. The fiber posts were then cemented with self-etching resin cement. Bonded specimens were cut (1-mm-thick), the first slice of the coronal 3rd was used for dentin microhardness analysis, and other slices were used for the push-out bond strength test. The data were statistically analyzed by using Shapiro-Wilk, Oneway ANOVA, and the Games-Howell test. Results: The lowest microhardness was observed in HEBP-NaOCl and NaOCl (p<0.05). CHX, HEBP, and EDTA resulted in less reduction in microhardness as compared to other groups (p<0.05). HEBP-NaOCl and NaOCl showed significantly higher mean bond strength to root dentin in the cervical thirds than in other groups (p<0.05). Conclusion: With regard to the push-out bond strength of the fiber post to dentin, NaOCl and HEBP-NaOCl increased bond strength compared to other groups. NaOCl and HEBP-NaOCl have lower microhardness of dentin. Compared to HEBP, EDTA increases microhardness and does not make a significant difference in push-out bond strength. Therefore, it is recommended to use HEBP alone.

A composite resin core with a new zirconia tube reduces the surface strain at the cervical area of a mandibular molar: A model tooth study.

This study aimed to evaluate the surface strain at the cervical area of endodontically treated molars with a large pulp chamber restored using a composite resin core with three different types of core build-up systems. Reproduction models of human mandibular molars with prepared post spaces were used in this study. Roots duplicated with a composite resin were used as the experimental teeth. Three types of core build-up systems were used: composite resin core(RC), composite resin core with fiber posts (FC), and composite resin core with a prefabricated zirconia tube (ZC). Each group comprised eight specimens. Crowns made of yttria partially stabilized zirconia were cemented with dual-cure resin cement. Four strain gauges were attached to the surfaces of each specimen: the cervical area of the root and crown, on the buccal and lingual sides. The surface strain at each cervical area was measured using a static loading test and statistically analyzed. In the case of static loading to the buccal cusp inner slope, ZC showed a significantly lower strain than RC in the crown on the buccal side and in the root and FC in the root. In the central fossa, ZC showed a significantly lower strain than FC in the root on the lingual side. The prefabricated zirconia tube reduced the surface strain at the cervical area of the buccal/lingual root in molars; however, the effect was small in the cervical area of the crown.

Do irrigation solutions used during root canal instrumentation influence the adhesion of glass fiber posts? A systematic review

Do irrigation solutions used during root canal instrumentation influence the adhesion of glass fiber posts? A systematic review

Which irrigating provides a better bond strength in glass fiber posts: Chlorhexidine or Sodium Hypochlorite? A systematic review with meta-analysis.

The aim of this systematic review and meta-analysis was to evaluate the influence of the use of chlorhexidine on endodontic instrumentation on the bond strength of glass fiber posts with resin cements. The guiding question of the study was: "Is the bond strength of glass fiber posts greater when using chlorhexidine as an irrigator in endodontic treatment instead of sodium hypochlorite?". This study was conducted according to Guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). In vitro studies were included that have compared chlorhexidine and sodium hypochlorite as an endodontic irrigator in the chemical-mechanical preparation. Eight studies were included in the qualitative analysis and seven in the meta-analysis. Both the analysis by subgroups and the total analysis, using a random effect model, showed no statistically significant differences between the groups (p> 0.05), either in the specific analysis for cervical root third (p = 0.30; 95% CI = -2.11, 6.91) or medium (p = 0.05; 95% CI = -0.03, 4.56), or nonspecific regarding the third to the root third (p = 0.48; 95% CI = -4.00, 1.86). There are no statistically significant differences in the bond strength of glass fiber posts and resin cements in teeth endodontically treated under irrigation by both chlorhexidine and sodium hypochlorite. Key words:Chlorhexidine, sodium hypochlorite, bond strength, glass fiber post.

Influence of Biological Dentin Post on Fracture Resistance of Endodontically Treated Anterior Teeth: A Systematic Review

Introduction: A biological dentin post is recommended when more support for the restoration is needed and there is a severe loss of tooth structure. However, whether the use of biological dentin post affects the fracture resistance of the restored anterior teeth is not impervious. Aim: This systematic review aimed to evaluate the fracture resistance of endodontically treated and restored anterior teeth and to answer the research question, “Does the use of biological dentin post influence fracture resistance of endodontically treated anterior teeth?” Materials and Methods: In the present systematic review, the initial search was performed on PubMed, Scopus, Web of Science, EBSCO, and Cochrane. According to inclusion criteria, additional records from all other resources like the citation database of related articles were also performed. The articles were searched between January 2000 to December 2021. The risk of bias was evaluated by using the Cochrane risk of bias assessment tool. The keywords for search strategy were “Biological Dentin Post” OR “Dentin Post” OR “Biological Post” OR “Experimental Dentin Post” AND “Fracture Resistance” OR “Dentin Post Failure” OR “Biological Post Failure” Results: After removal of duplicates and title and abstract screening, five studies met the inclusion criteria. Three studies were considered having/showing high-risk of bias and two studies were considered having/showing medium risk. The data concluded that the biological dentin post exhibited higher fracture resistance in three studies. However, one study concluded that both dentin post and glass fibre post may be preferred for additional reinforcement of immature teeth. Another study disclosed that human dentin, bovine dentin and prefabricated glass fibre posts presented similar values of fracture resistance. Conclusion: The use of biological dentin post increases the fracture resistance of endodontically treated and restored teeth. Also, future studies should follow a standardised approach to implementation and reporting of data.

Bond Strength and Failure Mode of Glass Fiber Posts with Different Surface Treatments Prior to Silanization: An In Vitro Comparative Study.

The use of chemical agents in the surface treatment of glass fiber posts can improve their bond strength to the root canal. The aim of this study was to assess the bond strength and failure mode of glass fiber posts that received different surface treatments prior to silanization. In this cross-sectional and in vitro experimental study, 50 human lower premolar roots were randomly divided into five groups and subsequently prepared to receive the cementation of a fiberglass post prior to silanization. They were distributed as group 1 (with 24% hydrogen peroxide), group 2 (with 37% phosphoric acid), group 3 (with 1.23% acidulated phosphate fluoride for 2 minutes), group 4 (with 1.23% acidulated phosphate fluoride for 6 minutes), and group 5 (without pretreatment). After cementation, the roots were sectioned into two discs for each cervical, middle, and apical region. Bond strength was assessed using the push out technique. Adhesive, mixed, and cohesive failure modes were also assessed. For data analysis, ANOVA and Tukey's post hoc tests were used, as well as Pearson's chi-square test. A significance of P < 0.05 was considered in all statistical analyses. When comparing the bond strength of root regions, significant differences were obtained in groups pretreated with phosphoric acid (P = 0.018) and acidulated phosphate fluoride for 2 and 6 minutes (P = 0.001 and P = 0.000, respectively). Furthermore, significant differences were obtained between posts treated only with silane and those that received phosphoric acid pretreatment (P = 0.006) and acidulated phosphate fluoride for 6 minutes (P = 0.001). Significant association of mixed failure mode was observed with hydrogen peroxide (P = 0.014) and phosphoric acid (P = 0.006) pretreatments. Cohesive failure was significantly associated with acidulated phosphate fluoride pretreatment for 2 minutes (P = 0.032) and with posts that did not receive treatment prior to silanization (P = 0.000). Posts treated only with silane and pretreated with hydrogen peroxide and acidulated phosphate fluoride for 2 minutes presented significantly higher bond strength with respect to those pretreated with phosphoric acid and acidulated phosphate fluoride for 6 minutes. However, acidulated phosphate fluoride for 2 minutes and silane were associated with a better bonding type.

Effect of laser surface treatment of glass fiber posts on their bond strength to intra-radicular dentin at different root levels: An in-vitro study

Statement of the problem: Despite the fact that adhesive luting is recommended for teeth rehabilitation with glass fiber posts, the most common failure of these restorations is debonding of the glass fiber posts.Aim: To evaluate the effect of laser surface treatment of glass fiber posts on their bond strength to intra-radicular dentin at different root levels.Materials and Methods: Twenty extracted single-rooted permanent human teeth were decoronated and endodontically treated. Post space of 10 mm length was prepared to receive glass fiber post. Teeth were randomly divided into 2 groups based on the surface treatment applied to the post surface as follows; Group A (Control): post surface received conventional silane treatment, Group B: Er:YAG laser was applied to the post surface followed by silane application. Prepared post spaces of all teeth were irrigated using standard irrigation protocol then dried and self-adhesive resin cement was used for posts cementation. For push-out bond strength evaluation, three slices for each sample were prepared, and the test was performed using a universal testing machine at a crosshead speed of 1 mm/min.Results: Statistical analysis showed that group B provided significantly higher bond strength values compared to group A. When different root sections were compared in each group: group A showed a significantly higher bond strength values in the middle and apical sections compared to cervical (p0.05). In addition, the Comparison between both groups in each section revealed that: group B showed significantly higher bond strength values in cervical and apical sections than group A. While in the middle section, group B recorded a non-significant increase in the bond strength compared to group A. Conclusion: Er: YAG laser treatment for the post surface can be used as an alternative to conventional silane treatment to enhance its bonding to intra-radicular dentin.

Application of polyetheretherketone (PEEK) posts: evaluation of fracture resistance and stress distribution in the root: in vitro and finite element analyses.

To evaluate the feasibility of using a milled polyetheretherketone (PEEK) post and core in endodontically treated teeth with or without a ferrule. Sixty bovine tooth roots were endodontically treated followed by cementation of intraradicular retainers (IR), according to each experimental group: a) non-ferrule glass fiber post (f0FP); b) 2-mm-ferrule glass fiber post (f2FP); c) non-ferrule resized glass fiber post (f0PR); d) 2-mm-ferrule resized glass fiber post (f2PR); e) non-ferrule PEEK post and core (f0PPC); and f) 2-mm-ferrule PEEK post and core (f2PPC). Metal crowns were made and cemented. A periodontal ligament was simulated using polyether. A force was applied to the palatine portion of each sample at 45°, until fracture. Fracture resistance data were submitted to two-way ANOVA and Tukey's test (α = 0.05). Three-dimensional digital models were developed to calculate the tensions formed in the root using finite element analysis. Models of glass fiber posts and PEEK posts and cores were evaluated with or without a ferrule. The results were analyzed by the Mohr-Coulomb criterion. The type of IR was not influenced by fracture strength (p = 0.243). There were significant statistical differences among the remaining factors. Ferrule groups had greater fracture resistance, and the failure mode of teeth with a ferrule was more catastrophic than the non-ferrule group. A ferrule increases fracture resistance and influences failure mode; the PEEK post and core did not modify the biomechanics of endodontically treated teeth, and resembled the glass fiber post results. The crack initiation point differed between the ferrule and non-ferrule groups.

The impact of irrigation procedures on the bond strength of fiber posts cemented with two different adhesive techniques

Introduction. Endodontically treated teeth are usually weaker due to the loss of tooth structure. As most of the crown of the tooth is destroyed, the most common retention for restoration is application of a fiber-reinforced composite posts in the root canal. In endodontically treated teeth, there are two main problems in the restorative procedure: reduced resistance of the remaining tooth structure and choosing the necessary adequate retention for restoration. The aim of this work was to evaluate the impact of irrigation protocol on the bond strength of two types of fiber posts luted with two different adhesive cements. Materials and method. In this in vitro study, 48 single-rooted teeth (incisors, single-rooted second premolars) extracted for orthodontic and periodontal reasons were used. The teeth were divided into the four groups of 12 teeth depending on the type of fiber post used as well as the irrigation agent. Each group was further divided into the two subgroups of six teeth depending on the material and cementation technique. Results. In all cross-sectional statistics the difference appeared only when different types of irrigants were used and they changed bond strength between dentin and bonding material. Conclusions. Irrigation protocol has a significant influence on the bond strength of composite post, independent of the type of post and cementation material used.

Preference for Postendodontic Restoration for Fractured Anterior Teeth: A Questionnairebased Cross-sectional Study among Dentists in Maharashtra, India

Introduction: One of the common dilemmas faced by today’s clinicians is the management of structurally and aesthetically compromised endodontically treated teeth due to various treatment options available. There is no one factor which is the sole determinant for treatment planning. And there are various parameters contributing to the long-term success of a postendodontic restoration, especially in a fractured anterior tooth. Aim: This study is aimed to investigate the preference for postendodontic restoration for fractured anterior teeth with respect to the tooth structure and aesthetics. Materials and Methods: This cross-sectional study was conducted in the Department of Conservative Dentistry and Endodontics, Government Dental College and Hospital, Nagpur, Maharashtra, India, from August 2021 to December 2021 among 150 clinicians in Maharashtra. A validated questionnaire containing 17 close-ended questions was given to the participants which ascertained their treatment choices, the importance of preserving the tooth structure, aesthetics and the consideration given to the physical properties while choosing the material and planning the treatment. Data obtained from the survey were statistically analysed by the Chi-square test. Results: The mean age of the participants was 30.25±9.08 years. Among the 150 participants, postgraduates were 60 (40%) followed by general dentists 38 (25.3%), endodontists 36 (24%) and other specialists 16 (10.7%). Out of total, 82 (54.7%) preferred composites when more than 50% of the tooth structure remained. Crowns increased the longevity of the tooth according to 50 (83.3%) postgraduates. Among them, 28 (77.8%) endodontists opted for IPS Emax crowns over zirconia veneer for better aesthetics, 71 (47.3%) preferred glass fibre posts and 113 (75.3%) preferred ideal ferrule for better fracture resistance. Reattachment of the fragment was also a preferred option in all groups. Conclusion: A 77.8% of the endodontists preferred IPS Emax crowns while 71.1% of the general dentists preferred zirconia veneers. Good awareness was seen among endodontists regarding method, patient preferences and aesthetics, very good awareness in materials and excellent awareness in treatment choices. More awareness is needed among general dentists, postgraduates, and other specialists in terms of treatment methods.

Multifunctional epoxy resin-based composites with excellent flexural strength and X-ray imaging capacity using micro/nano structured QF-Bi2SiO5 fillers.

Composites have been widely applied in various industries and are beneficial in attaining complicated functionalities. Particularly, for dental fiber posts or orthopedic implants, the composites should have excellent mechanical properties and good imaging effects for visualization in vivo. The traditional method to improve mechanical strength and visibility by adding reinforcing fillers and radiopacifiers is complicated and has poor distributions and long production times. Hence, fabricating an integrated reinforced filler with radiopacity is of considerable economic and social significance. After ball-milling and sintering quartz fiber (QF) and bismuth trioxide (Bi2O3), a multifunctional filler (QF-Bi2SiO5) is fabricated to impart excellent flexural strengths and high X-ray imaging qualities to the composites. A composite made of epoxy resin (EP) and QF-Bi2SiO5 has a high bending strength (126.87 ± 6.78 MPa) and bending modulus (3649.31 ± 343.87 MPa), which are attributed to the tight mechanical interlock between EP and micro/nano structures of QF-Bi2SiO5. The QF-Bi2SiO5/EP composite shows good X-ray imaging quality owing to the Bi2SiO5 crystal. Furthermore, the mechanical and imaging performances of various composites with commercial fillers were compared with that of the QF-Bi2SiO5/EP composite. No filler was found that can perform both functions as well as QF-Bi2SiO5. Hence, the fabricated composites containing micro/nano structured QF-Bi2SiO5 fillers have the potential to be used in a variety of fields requiring mechanical strength and X-ray imaging capability.

Effect of manufacturing techniques and surface treatment of custom-made polyetheretherketone posts on the shear bond strength to resin cement versus customized fiber posts

Effect of manufacturing techniques and surface treatment of custom-made polyetheretherketone posts on the shear bond strength to resin cement versus customized fiber posts

Effect of Er:YAG laser on removal of fibre posts from root canal.

The aim of this study was to evaluate the efficiency of Er:YAG laser in translucent fibre post removal. 60 human single-rooted anterior teeth were divided into three groups (n=20) according to post diameters (Exacto1-E1, Exacto2-E2, Exacto3-E3) and subdivided according to laser application. Fibre posts were cemented to endodontically treated teeth, and the specimens were sliced with a thickness of 1.0 ± 0.2 mm. Er:YAG laser was applied and the push out bond strength test was performed. Two-way analysis of variance was used to perform the statistical analysis. Push out bond strengths at apical area were significantly lower in all test groups (p < 0.05). Laser application caused increase in all radicular thirds, but it was significant for E1 and E3 groups. Laser application to the post-dentine interface enhances the connection between post and dentine.

Biomechanical behavior of weakened roots restored with custom-made post-and-cores of glass fiber and polyetheretherketone.

To evaluate the influence of post type and mechanical aging on compression force resistance, fracture pattern, and stress distribution in weakened roots. Bovine roots were endodontically treated and widened-and randomly divided into 8 groups (n = 10) according to post type (prefabricated glass fiber post and customized anatomic glass fiber post, milled glass fiber post-and-core, and milled polyetheretherketone post-and-core) and mechanical aging (without and with mechanical aging). Three hundred thousand cycles of mechanical fatigue were performed and compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α = 0.05). Fracture patterns were reported and stress distribution was analyzed by finite elements analysis. There was a significant effect of post type (p = 0.032) and mechanical aging (p = 0.009), but no double interaction (p = 0.879). Higher values were recorded in the milled glass fiber and polyetheretherketone post-and-core groups compared to the prefabricated glass fiber post groups, and no significant difference was found among anatomic glass fiber post groups and other groups. Reparable fractures were predominant in the milled glass fiber and polyetheretherketone post-and-core groups. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution. Post type and mechanical aging influence the compression force resistance and fracture pattern of weakened roots. Milled glass fiber and polyetheretherketone post-and-cores exhibited higher compression force resistance and more reparable fractures compared to prefabricated glass fiber posts. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.

Comparative Evaluation of Artifacts Originated by Four Different Post Materials Using Different CBCT Settings.

Forty premolar teeth were used in this study. Root canals were treated, and teeth were randomly distributed into four subgroups (n = 10) for the preparation of post materials: titanium, gold (Nordin), quartz fiber (Bisco DT Light), and glass fiber (Rely X). The CBCT images were taken with two different kVps, three different metal artifact reduction (MAR) algorithm options, and two different resolutions. For each protocol, the effective dose was calculated according to the dose area production (DAP) value. The standard analysis of variance technique and the Tukey multiple comparison adjustment method were used to assess interactions among material types, kVp, MAR, and voxel settings. More artifacts were found in the middle third than in the cervical third (p &lt; 0.05). The mean value of artifacts was highest for gold (Nordin), 90 kVp, no MAR, and 100 voxel size. Glass or quartz fiber posts at low resolution, with high MAR and 96 kVp, originated fewer artifacts. Moreover, the use of 90 and 96 kVp with 200 voxel size and high MAR provided the least amount of radiation. The best setting for radiographic follow-up of post materials on the Planmeca ProMax is 96 kVp with low resolution and high MAR; this setting produced one of the lowest effective doses. This study estimated the best scanning protocol by lowering the effective dose to a minimum level according to the "as low as reasonably achievable" principle, as well as assessing the tooth region and the post material generating the fewest artifacts, in order to prevent image interpretation challenges such as false-positive and false-negative results stemming from the deterioration of the visibility of the root canal due to perforation, fractures, and voids in the root canal region.

Accuracy of a 3D printed sleeveless guide system used for fiber post removal: An in vitro study

ObjectivesThe removal of fiber post is often a challenging task. A 3D printed assembled sleeveless system that guides the head of the handpiece instead of the drill was developed to address this issue. This study aimed to evaluate the accuracy of this novel guide system using an in vitro approach. MethodsA standard maxillary typodont was digitized. The right first molar, the right central incisor, the left first premolar, and the left second molar in the digitized dentition were virtually crown-amputated. Four cylinders (diameter: 6 mm, height: 12 mm) were positioned along the directions of the main roots of these teeth to establish the virtual test model. Ten copies of the test model were printed using light-polymerizing resin. Four assembled sleeveless guide systems targeting the cylindrical axes were designed and printed using titanium alloy. One senior prosthodontist performed the drilling task targeting each cylindrical axis aided by the guide system or freehand (20 teeth each). The drilled models were scanned. The coordinates of the centers of all perforations and circular bases on the coronal and apical surfaces were obtained. The linear and angular deviations between the actual drilling path and the cylindrical axis for each tooth were calculated and analyzed. ResultsThe guided group exhibited significantly smaller linear and angular deviations than the freehand group (coronal linear deviation: 0.19 ± 0.09 mm vs. 0.35 ± 0.18 mm, p = 0.0012; apical linear deviation: 0.54 ± 0.19 mm vs. 1.71 ± 0.51 mm, p < 0.001; angular deviation: 2.67 ± 1.07° vs. 8.48 ± 2.86°, p < 0.001). ConclusionThe accuracy of the 3D printed assembled sleeveless guide system used for fiber post removal is superior to that of the freehand method within the limits of an in vitro design. Clinical significanceFor the removal of fiber posts, the present 3D printed sleeveless guide system can provide better accuracy that the conventional freehand method. This may justify the diffusion of the guided technique for fiber post removal.

The effectiveness of EDTA 17% as a cleaning solution for the fiber post space after filling with cements

Aim: To evaluate the resistance of the union between a glass fiber post and radicular dentine after cleaning the root with 17% EDTA and filling with different endodontic cements. Methods: Forty uniradicular bovine incisors were removed to obtain root lengths of 18 mm. Endodontic treatment was performed on all roots using different filling cements (zinc oxide and eugenol-based, OZE; cement based on epoxy resin, AH) and cleaning solutions (saline, SA or EDTA), which made it possible to obtain four groups: OZESA, OZEEDTA, AHSA and AHEDTA. Subsequently, 12 mm of filling material was removed from the roots, and they were prepared to receive fiber posts luted with resin cement. To execute the mechanical cycles (2x106 cycles, 90 N, 4 Hz), coronal reconstruction was performed with a silicon matrix. The roots were then sliced (2-mm thick) to perform the push-out test. The results were analyzed using analysis of variance (one factor and two factors) and Tukey’s test (α=0,05). Results: Bond strength (Mpa) was significantly higher for OZEEDTA (9,18) and AHEDTA (8,70) than for OZESA (6,06) AHSA (8,7). OZEEDTA also presented the highest values in the cervical region (15,18) but was significantly lower in the apical region (2,99). However, AHEDTA had a homogeneous bond strength in all thirds. Conclusion: Regardless of the endodontic cement used, EDTA was used as an irrigating solution, culminating in a higher bond strength between the glass fiber post and dentin.