Showing papers on "Post and core published in 2017"

Fracture resistances of zirconia, cast Ni-Cr, and fiber-glass composite posts under all-ceramic crowns in endodontically treated premolars.

Abstract: PURPOSE. The aim of the present study was to evaluate the fracture resistances of zirconia, cast nickel-chromium alloy (Ni-Cr), and fiber-composite post systems under all-ceramic crowns in endodontically treated mandibular first premolars. MATERIALS AND METHODS. A total of 36 extracted human mandibular premolars were selected, subjected to standard endodontic treatment, and divided into three groups (n=12) as follows: cast Ni-Cr post-and-core, one-piece custom-milled zirconia post-and-core, and prefabricated fiber-glass post with composite resin core. Each specimen had an all-ceramic crown with zirconia coping and was then loaded to failure using a universal testing machine at a cross-head speed of 0.5 mm/min, at an angle of 45 degrees to the long axis of the roots. Fracture resistance and modes of failure were analyzed. The significance of the results was assessed using analysis of variance (ANOVA) and Tukey honest significance difference (HSD) tests (α=.05). RESULTS. Fiber-glass posts with composite cores showed the highest fracture resistance values (915.70±323 N), and the zirconia post system showed the lowest resistance (435.34±220 N). The corresponding mean value for the Ni-Cr casting post and cores was reported as 780.59±270 N. The differences among the groups were statistically significant (P < .05) for the zirconia group, as tested by ANOVA and Tukey HSD tests. CONCLUSION. The fracture resistance of zirconia post-and-core systems was found to be significantly lower than those of fiberglass and cast Ni-Cr post systems. Moreover, catastrophic and non-restorable fractures were more prevalent in teeth restored by zirconia posts. © 2017 The Korean Academy of Prosthodontics.

In vitro fracture resistance of endodontically treated premolar teeth restored with a direct layered fiber-reinforced composite post and core

Abstract: Methods for restoring endodontically treated teeth fall short of restoring the physiologic mechanical properties. Fracture of endodontically treated teeth is a common type of clinical failure. New treatment modalities or perfected versions of existing treatment concepts need to be tested to find a biomimetic solution. A novel method of restoring endodontically treated teeth is presented and compared in vitro with currently accepted restorative methods. Seventy-two extracted and endodontically treated maxillary premolar teeth were divided into six groups (n = 12) depending on restorative technique (Groups 1–6). Group 1: fiber-reinforced composite post (FRC), Group 2: direct layered short FRC post and core, Group 3: short fiber-reinforced obliquely layered composite restoration, Group 4: microhybrid composite restoration, Group 5: fiber-reinforced box, Group 6: control. Specimens were submitted to static fracture resistance test. Fracture thresholds and fracture patterns were evaluated. Group 6 exhi...

Stress generation in mandibular anterior teeth restored with different types of post-and-core at various levels of ferrule.

Abstract: Statement of problem Pertinent evidence regarding the mechanical integrity of mandibular anterior teeth restored with a post-and-core is limited. Purpose The purpose of this finite element analysis study was to compare the impact of the post type (glass fiber post-and-resin core or cast post-and-core) along with the ferrule effect on the stress fields generated in endodontically treated mandibular lateral incisors and canines. Material and methods Three-dimensional models of the segmented mandible were developed. Mandibular incisors and canines with or without a 2-mm circular ferrule and restored with a cast post-and-core or glass fiber post-and-resin core were simulated and subjected to linear elastic static analysis. The principal stress values were calculated. von Mises equivalent stresses were used to evaluate the stress. Results Maximum principal stresses in dentin were highest in incisors, with a ferrule. Stress parameters in composite resin core in both incisors and canines were critically close to the tensile failure limit of the core material. Cast post-and-cores cemented in incisors without a ferrule accumulated the highest stresses, exceeding the tensile failure limit of resin-modified glass ionomer cement. Conclusions Tooth preparation with a ferrule led to a remarkable rise in stress in the dentin of mandibular incisors but favored the mechanical integrity of the restoration.

Post and core build-ups in crown and bridge abutments: Bio-mechanical advantages and disadvantages.

Abstract: Dentists often place post and core buildups on endodontically treated abutments for crown and bridge restorations. This article analyzes the bio-mechanical purposes, advantages and disadvantages of placing a core or a post and core in an endodontically treated tooth and reviews literature on post and core biomechanics. The author assesses the scientific rationale of the claim that the main purpose of a post is to retain a core, or the claim that posts weaken teeth. More likely, the main function of a post is to help prevent the abutment, on which a crown is cemented, from fracturing such that the abutment separates from the tooth root, at a fracture plane that is located approximately and theoretically at the level of the crown (or ferrule) margin. A post essentially improves the ferrule effect that is provided by the partial fixed denture prosthesis. This paper also explores the difference between bio-mechanical failures of crowns caused by lack of retention or excess taper, versus failures due to a sub-optimal ferrule effect in crown and bridge prostheses.

Fracture Resistance of Endodontically Treated Teeth Restored with Biodentine, Resin Modified GIC and Hybrid Composite Resin as a Core Material.

Abstract: Introduction The restoration of a severely damaged tooth usually needs a post and core as a part of treatment procedure to provide a corono - radicular stabilization. Biodentine is a class of dental material which possess high mechanical properties with excellent biocompatibility and bioactive behaviour. The sealing ability coupled with optimum physical properties could make Biodentine an excellent option as a core material. Aim The aim of the study was to determine the fracture resistance of Biodentine as a core material in comparison with resin modified glass ionomer and composite resin. Materials and methods Freshly extracted 30 human permanent maxillary central incisors were selected. After endodontic treatment followed by post space preparation and luting of Glass fibre post (Reforpost, Angelus), the samples were divided in to three groups based on the type of core material. The core build-up used in Group I was Biodentine (Septodont, France), Group II was Resin-Modified Glass Ionomer Cement (GC, Japan) and Group III was Hybrid Composite Resin (TeEconom plus, Ivoclar vivadent). The specimens were subjected to fracture toughness using Universal testing machine (1474, Zwick/Roell, Germany) and results were compared using One-way analysis of variance with Tukey's Post hoc test. Results The results showed that there was significant difference between groups in terms of fracture load. Also, composite resin exhibited highest mean fracture load (1039.9 N), whereas teeth restored with Biodentine demonstrated the lowest mean fracture load (176.66 N). Resin modified glass ionomer exhibited intermediate fracture load (612.07 N). The primary mode of failure in Group I and Group II was favourable (100%) while unfavourable fracture was seen in Group III (30%). Conclusion Biodentine, does not satisfy the requirements to be used as an ideal core material. The uses of RMGIC's as a core build-up material should be limited to non-stress bearing areas. Composite resin is still the best core build-up material owing to its high fracture resistance and bonding to tooth.

Comparison of resistance to fracture between three types of permanent restorations subjected to shear force: An in vitro study

Abstract: Introduction: Our study's objective was to compare resistance to fracture between endocrown and conventional post and core restorations when subjected to shear force. Materials and Methods: Thirty human mandibular premolars were extracted for orthodontic reasons, endodontically treated, and restored using three different methods: endocrown, glass fiber post and composite resin core, and metal post. All the crowns were made from IPS e.max ceramic. Shear forces were applied to these restorations using a test machine until breakage. Load and displacement were recorded every 0.1 s. Results: No significant difference was observed in resistance to fracture between glass fiber post and metal post. No relationship between the displacement of prosthetic dental system and type of material used was uncovered and by comparing the type of fracture with the restoration material used. However, a greater number of favorable fractures were observed in the glass fiber group whereas most of the fractures in the endocrown and metal post groups were unfavorable. Conclusion: Endocrown displays better resistance to fracture compared to conventional post and core restorations. In addition, endocrown did not show more displacement or cause more unfavorable fractures than the conventional restorations. This restoration may represent a reliable alternative for restoring a damaged, endodontically treated tooth.

Effect of Different Ferrule Length on Fracture Resistance of Endodontically Treated Teeth: An In vitro Study.

Abstract: INTRODUCTION A ferrule has been described as a key element of tooth preparation when using a post and a core It is a vertical band of tooth structure at the gingival aspect of crown preparation It lessens the stress transmission to the root which is due to forces from posts or bending during seating of the post The incorporation of a ferrule can help to withstand the forces of occlusion, preserve the hermetic seal of the luting cement, and minimize the concentration of stresses at the junction of post and core AIM To evaluate and compare the effect of ferrule length on fracture resistance of endodontically treated mandibular premolar teeth, restored with prefabricated glass fiber post luted with resin cement, composite core and a full coverage metal crown MATERIALS AND METHODS Forty freshly extracted mandibular premolars were treated endodontically They were randomly divided into four groups according to their ferrule height: 3 mm, 2 mm, 1 mm and 0 mm (no ferrule) All specimens were restored with prefabricated glass fibre posts (Reforpost, Angelus) and composite resin (Filtek™ Z250XT) Standardized preparation was done on each specimen to receive a cast metal crown The specimens were thermocycled and compressive static load at a crosshead speed of 1 mm/min was applied at an angle of 30° on lingual incline of buccal cusp of the crown until failure occurred The load (N) at failure and mode of failure were recorded Statistical analysis was performed with Kruskal Wallis test RESULT Fracture resistance values among the groups was found to be statistically significant (p<0001) The 3 mm ferrule group had significantly higher failure load (97199±13307) compared to 2 mm (84884±10960), 1 mm (71464±13389) and 0 mm ferrule groups (52936±11995) More favourable failure modes were observed in almost all groups CONCLUSION The results of this study showed that fracture resistance of endodontically treated teeth increases as ferrule length increases

Impact of Root Dentin Thickness on the in vitro Compressive Strength of Teeth treated with Recent Post and Core Systems.

Abstract: INTRODUCTION Endodontically treated teeth dry with time, and its dentin undergoes changes making the teeth brittle and friable. The main function of a post is to strengthen or reinforce a weakened root. However, doing a post and core frequently requires the removal of sound tooth tissue. Recent materials introduced in the market for post and cores have been promising. AIM The aim of this study is to evaluate the fracture resistance of endodontically treated extracted permanent teeth with variable remaining root dentin thickness after post space preparation. MATERIALS AND METHODS A total of 270 freshly extracted permanent maxillary central incisors with fully formed apices were selected, decoronated at cementoenamel junction, and divided into three main groups according to remaining root dentin thickness, determined using a Vernier caliper into 0.5, 1, and 1.50 mm after post space preparation. Each group was further divided into three subgroups (subgroup a: Custom-made cobalt-chromium alloy post and core; subgroup b: Prefabricated glass fiber post and composite core; and subgroup c: EverStick fiber post). Each specimen was subjected to compressive load using universal testing machine. The force required to fracture was recorded and data were analyzed using analysis of variance (ANOVA) test. RESULTS Analysis of variance revealed that compressive strength of the tooth is significantly affected by the increase in the remaining dentin thickness after post space preparation (p < 0.05). Furthermore, teeth with custom fabricated posts showed a significantly higher compressive strength (p < 0.05) than prefabricated glass fiber post and EverStick fiber post groups except the group with minimum remaining dentin thickness. CONCLUSION The present in vitro study revealed that compressive strength of the post and core systems is directly related to the amount of healthy remaining dentin thickness. Hence, efforts to maximize the preservation of natural dentin should be taken during post space preparation.

Comparison of Different Post Systems for Fracture Resistance: An in vitro Study.

Abstract: INTRODUCTION Endodontic restoration becomes a challenging task for the clinician because of severe loss of coronal tooth structure owing to trauma, caries, restorative, and endodontic procedures. The restoration of these teeth requires the use of a post and core as individual units or as abutment supports for fixed or removable restorations in a predictable long-term manner. AIM To compare and assess the compressive bond strength of glass, quartz, and carbon fiber posts restored with porcelain-fused-to-metal (PFM) crown. MATERIALS AND METHODS A total of 45 upper central incisor teeth having straight root canals, similar anatomically root segments, and fully developed apices were selected. Teeth were divided into three groups of 15 teeth after endodontic treatment. Group I: Teeth inserted with the prefabricated glass fiber post. Group II: Teeth inserted with the quartz fiber post. Group III: Teeth inserted with carbon fiber post. The posts were placed and core was fabricated using composite restoration followed by PFM crown cementation using adhesive resin. Compressive load required to fracture the tooth was measured using a universal loading machine. The difference between the variables was assessed by one-way analysis of variance, followed by Tukey's post hoc test. RESULTS The compressive strength exhibited by carbon fiber posts was highest with a mean of 668.33 ± 26.397, followed by quartz fiber post (635.80 ± 30.390). Least compressive strength was exhibited by glass fiber post (567.53 ± 26.632). An analysis of variance shows statistically highly significant difference (p < 0.005) among the posts used. CONCLUSION This study concluded that the carbon fiber posts had higher compressive strength than other quartz, glass fiber posts. CLINICAL SIGNIFICANCE Endodontic treatment results in loss of a significant part of the tooth structure. Posts restore these teeth and provide retention.

Fracture resistance of single-rooted pulpless teeth using hybrid CAD/CAM blocks for post and core restoration.

Abstract: Purpose The purpose of this study was to determine whether there is a significant difference in the fracture strengths of hybrid computer-aided design/computer-aided manufacturing (CAD/CAM) blocks and fiber posts for post and core restorations in both ferrule and nonferrule pulpless mandibular canines. Materials and method Forty extracted human mandibular canines were divided into ferrule and nonferrule groups and restored with hybrid CAD/CAM blocks using either the CAD/CAM system or fiber posts (control). Thus, there were four subgroups of ten specimens each. A 45-degree oblique load was applied with a crosshead of 0.5 mm/min, and the fracture loads were recorded. The mode of fracture was evaluated using an optical microscope at 3× magnification, and the data were tabulated and statistically analyzed using the Mann-Whitney U test and the t test, respectively, for the existence of significant difference at a 0.05 significance level. Results No statistically significant difference was found between the fracture strength under oblique loading when using hybrid CAD/CAM blocks and fiber posts in both ferrule and nonferrule groups. The failure mode distribution of the nonferrule group presented no unfavorable failures, whereas failures in the ferrule groups were spread out between the Favorable and Unfavorable groups. Conclusions The results show that hybrid CAD/CAM blocks can be considered as an alternative restorative system in post and core restorations. Further basic and clinical research should be conducted to support the improvement of this system.

Sealing Ability of Esthetic Post and Core Systems.

Abstract: Aim To review the literature on the sealing ability of esthetic post systems with different cementation techniques. Background An important factor for successful root canal treatment is the development of a coronal seal to the treated root canal system. Review result: The current literature describes promising results using fiber posts with a dual-cure, self-etch resin cement system. However, none of the published results describe a post system or cementation technique that achieved a homogeneous and tight coronal seal. Conclusion Fiber post systems appear to be favorable alternatives to metallic or ceramic post systems. Furthermore, dual-cure, self-etch resin cement systems represent superior alternatives to other cement systems. Clinical significance The clinician should be aware of the differences between various post systems and different cement systems to select and apply the most appropriate post and cement in each clinical situation.

The effects of post and core material combination on the surface strain of the 4-unit zirconia fixed partial denture margins.

Abstract: The suitability of various post and core materials for the 4-unit zirconia fixed partial denture abutment teeth was investigated to lower stress concentration. Artificial mandibular teeth (44 and 47) were used as the abutment teeth. There were two types of posts and cores: resin composite with glass fiber posts (RC), and cast platinum gold alloy (MC). Two experimental groups were analyzed. For Group RM, the premolars were restored with RC and the molars were restored with MC. For Group MR, the premolars were restored with MC and the molars were restored with RC. Static loading was applied to the occlusal surfaces, and the surface strain of the frameworks and roots was measured with a strain gauge. Group RM had a greater number of statistical differences between premolars and molars compared to Group MR. This result suggests that the Group MR post and core material combination reduces stress concentration.

Push‑out bond strength of different intracanal posts in the anterior primary teeth according to root canal filling materials

Abstract: Background: This study was carried out to evaluate the effect of root canal filling on the bond strength of three intracanal posts in the primary incisors. Materials and Methods: Sixty primary incisors were prepared and then divided into two groups ( n = 30). The first group canals obturated with zinc oxide eugenol (ZOE) and Group 2 canals obturated with Metapex. Further, the two group categories were divided into three subgroups ( n = 10): (1) short composite post (SCP), (2) glass fiber posts (GFPs) cemented with flowable composite, and (3) GFP with glass ionomer cement (GFP + GIC). The push‑out test was performed with a universal testing machine. The results were statistically analyzed with two‑way analysis of variance.(α = 0.05). Results: The mean bond strength of the first group obturated with ZOE was lower than that of the second group obturated with Metapex ( P = 0.046). Moreover, from a statistical point of view, in all three subgroups, the correlation of mean push‑out bond strength between SCP and GFP coated with flowable composite was not substantial at P = 0.97. However, the mean bond strength of SCP was in fact significantly greater than that of the GFP coated with GIC since P = 0.034. Conclusion: Using ZOE resulted in the significant reduction of the mean bond strength of the intracanal posts when utilized in the primary anterior teeth. Likewise, SCP and GFP coated with flowable composite showed higher push‑out bond strengths for restoring primary anterior teeth. Key Words: Composite dental resin, Metapex, post and core technique, primary tooth, zinc oxide eugenol cement

[Comparison of clinical effects of Co-Cr alloy cast post-core and everStick fiber post in restoration of labially or lingually inclined maxillary central incisor].

Abstract: PURPOSE To compare the clinical effect of Co-Cr alloy cast post-core and everStick fiber post in restoration of maxillary central incisor with labial or lingual inclination, and provide theoretical basis for clinical application. METHODS Ninety-seven labially or lingually inclined maxillary central incisors were treated in our hospital from March 2012 to March 2014. The patients were randomly divided into group A (n=49) and group B (n=48), and received post -core and crown restoration. Patients in group A underwent Co-Cr alloy cast post and core restoration and patients in group B underwent everStick fiber post and core restoration. After two-year of follow-up, root fracture, post break, crown or post dislodgment and gingival marginal discoloration were recorded and analyzed using SPSS 19.0 software package. RESULTS Chi-square test showed that the success rate of restoration was significantly different between 2 groups (P<0.05). The incidence of root fracture and gingival marginal discoloration of Co-Cr alloy cast post-core was higher than that of everStick fiber post, but there was no significant difference in the incidence of post break, crown or post dislodgment. CONCLTSIONS EverStick fiber post is better than Co-Cr alloy cast post and core to prevent root fracture and gingival marginal discoloration. Its fracture pattern is repairable and favorable for preserving tooth.

Push-out bond strength of glass fiber posts luted with two resin cements

Abstract: Objective. To evaluate the bond strength of a prefabricated glass fiber post to the root dentin with two resin cements using the push-out test. Material and Methods. Thirty fiber posts (White Post ECD) were cemented in human endodontically treated anterior teeth with two resin cements (n=15): RelyxTM ARC and AllCem. The roots were transversely sectioned and divided in cervical, middle and apical thirds after 48 h of cementation. The specimens' retention was tested by push-out method. The results were analyzed by 2-way ANOVA and Tukey’s test (p<0.05). Results. There were no significant differences in the bond strength between the resin cements. The bond strength was higher in cervical third than in middle and apical thirds for both resin cements. It was observed higher percentages of adhesive failures followed by mixed. Conclusions. Both resin cements are indicated in the cementation of glass fiber post.KeywordsDental prosthesis; Post and core technique; Biomechanical phenomena.

Fabrication of cast post and core by a modified indirect procedure and postcementation using a novel technique

Abstract: The restoration of endodontically treated pulpless teeth is a challenging dental procedure. Post and core is indicated in cases of extensive coronal tooth destruction where additional retention is required. The post is used to retain a core that can be used to retain definitive prosthesis. The choice between using a cast post and a prefabricated post depends on multiple factors such as canal configuration and remaining tooth structure. It has been said that if a canal requires extensive preparation, a well-adapted cast post and core will be more retentive than a prefabricated post that does not match the canal configuration. The cast post and core is fitted to the prepared root canal space and designed to resist torsional forces. However, one drawback of cast post is its tedious and time-consuming wax pattern technique. In this case report, we have used a time saving modified indirect technique for fabricating cast post and core, without the use of any reinforcement, no wax, no pattern resin but only rubber base impression material along with a novel technique of cementation, which utilizes a modified syringe with needle to facilitate even distribution of luting cement within the canal.

Vertical marginal gap distance and retention of different cad/cam ceramic endocrowns with two preparation designs

Abstract: Statement of the problem: The rehabilitation of severely damaged coronal hard tissue and endodontically treated teeth has always been a challenge in reconstructive dentistry. These teeth have been shown to exhibit a significantly shorter service life and an increased failure rate when compared with vital teeth. Objective: This study evaluated the vertical marginal gap distance and retention of bonded CAD/CAM Ceramic Endocrowns as a conservative alternative in endodontically treated molar teeth following thermal cycling and fatigue loading compared to post and core supported Ceramic crowns. Methods: Ninty caries free human molar teeth were selected and mounted in epoxy resin blocks. For vertical marginal gap distance test, sixty teeth were assigned into six groups (n=10) according to type of restoration as follows; GroupI: Endodontically treated teeth incorporating 1mm ferrule restored with IPS Empress CAD endocrowns. Group II: Endodontically treated teeth incorporating 1mm ferrule restored with IPS e.max CAD endocrowns. Group III: Endodontically treated teeth without incorporating ferrule restored with IPS Empress CAD endocrowns. Group IV: Endodontically treated teeth without incorporating ferrule restored with IPS e.max CAD endocrowns. Group V: Endodontically treated teeth incorporating 1mm ferrule restored with glass-fiber posts, composite cores and IPS Empress CAD crowns serving as a control group. Group IV:Endodontically treated teeth incorporating 1mm ferrule restored with glass-fiber posts, composite cores and IPS e.max crowns serving as another control group. For retention test, thirty teeth were divided into six groups (n=5). Same designs and types of restorations for the previous test were used for the retention test. All teeth were sectioned perpendicular to the long axis 2mm coronal to the proximal CEJ and then subjected to a standard endodontic treatment. A special milling machine was used for teeth preparation. All-Ceramic endocrowns and crowns were constructed using the Cerec InLab system and cemented with Rely x ARC dual cure adhesive resin cement. The vertical marginal gap distance was measured after cementation using a stereomicroscope. Measurements were made at twenty points for each specimen. In order to mimic the intraoral conditions, all the specimens were subjected to thermal cycling and fatigue loading in a pneumatic fatigue device. Mechanical fatigue was performed for 1,200,000 cycles in a water bath subjected to temperature changes between 5oC and 60oC. The vertical marginal gap distance was re measured at the same points to determine the effect of thermal cycling and fatigue loading. Retention was measured by dislodging the crowns along the long axis of the tooth using a computer controlled universal testing machine. The recorded data were tabulated and statistically analyzed. Results: Regarding the vertical marginal gap distance; endocrowns with 1 mm ferrule showed the statistically significant highest mean gap distance. There was no statistically significant difference between endocrowns without ferrule and post & core supported crowns. For endocrowns with 1 mm ferrule; Empress CAD scored statistically significant higher mean marginal gap values than e.max CAD. There was a statistically significant increase in mean gap distance after thermal cycling and fatigue loading for all test groups. Regarding the retention; endocrowns with 1 mm ferrule showed the statistically significant highest mean retention value. Post & core supported crowns showed statistically significant lower mean value. While, endocrowns without ferrule recorded the lowest mean retention value. In both endocrowns with 1 mm ferrule and post and core supported crowns e.max CAD scored statistically significantly higher mean retention values than Empress CAD, while for the endocrowns without ferrule there was no statistically significant difference between e.max CAD and Empress CAD. Conclusions: Endocrowns represent a successful conservative alternative to post and core supported crowns for restoring mutilated endodontically treated posterior teeth. All tested endocrown designs with both materials proved to have a clinically acceptable marginal gap distances. Preparation geometry for endocrown designs is a crucial factor for the retention of this kind of restorations

Nadogradnje u prevenciji i terapiji loma kliničke krune zuba

Abstract: Dental post and cores are tooth upgrades as a part of fixed-prosthetic treatment on the non vital tooth. They always serves as support for different types of crowns. The condition for upgrading the tooth structure and made post and core is a properly endodontically cured tooth. They are also indicated in all clinical situations, where there is a lack of clinical tooth crowns for the retintion the crown. Most commonly clinical situations for indication for posta and cores are non vital tooth crown fractures . They can be also needed in the abrasion of the teeth, where the reduction of the crown length is present, providing extension of the clinical crown length after endodontic procedure. Nowadays there are a lot of clinical procedures with the whole range of upgrades that differ in the manufacturing process, material and form, extracoronary and intraradular part of the upgrade. The basic clasiffication of the tooth upgrades is on individual post and cores and ready-made post and cores. Individual post and cores are much more precise because the upgrade is adjust to the tooth. The process of upgrading involves the co-operation of the dnetal laboratory thus extending the clinical procedure. Ready made upgrades comes as finished products in various shapes and materials and the tooth is needed to be adapted to them . The clinical procedure is shorter, but the open question remains, are we difined good indication of this type of substitution due to the size and shape of the extracoronal part of the ready made post and cores. The preparation of the tooth, especially of the intraradicular part of the upgrading is a very important and accurate procedure, and needs a skill of the doctor of dental medicine. The cementing process is also extremely important as well as the choice of cement types depending on the type and material of the post and core upgrade of the tooh.

Fracture resistance of different esthetic post and core materials and assessment their mode of failure

Abstract: Purpose: This in vitro study measured fracture resistance of different esthetic post and core materials and compare their modes of failures. Statement of problem: Increase esthetic demand and patient awareness have encouraged development of esthetic post and core systems. Translucency of ceramic restorations is accompanied by marked decrease in alumina content that may affect mechanical properties. Methods:40 extracted human central incisors were used in this study. Teeth were randomly divided into 4 groups of 10 each: group 1:Translucent Zirconia(TZ);group 2:High Translucency IPS E.Max (T-IPS); group 3:Polymer Infiltrated Ceramic (Vita Enamic) (PIC) and group 4: Control group (C), teeth were endodontically treated with no posts and cores. Posts and cores were processed according to manufacturer instructions cemented to teeth with adhesive resin cement; then specimens were mounted to acrylic resin blocks, attached to Instron universal testing machine, and loaded with a crosshead speed of 0.5 mm/min, until fracture. Types of failures were also recorded in different groups. Data were statistically analyzed using 1-way analysis of variance (ANOVA), and Scheffe test made pairwise comparison (α = 0.05). Results: TZ group showed the highest fracture resistance (454 .4±41.6 N). T-IPS showed higher results(360.4±35.7N) than PIC(300.9±35.6 N) and control(276.7±32.5 N) and the two latter groups were not significantly different from each other P <0.001.As regard mode of failure TZ showed 80% non-restorable type, T-IPS 40%,PIC 50% and control group showed 20% non-restorable type respectively.Conclusions: Regarding fracture strength and mode of failure, High Translucent IPS-E Max post and core can be an alternative treatment method when compared with other techniques.

A comparative evaluation of fracture resistance of endodontically treated teeth restored with three different post and core systems and two different luting agents – an invitro study

Abstract: Purpose: To compare fracture resistance and primary mode of failure of endodontically treated teeth with three different posts systems and two variant luting agents. Materials and Methods: Root canal treatment was performed on 40 maxillary incisors and samples were divided into 4 groups. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), prefabricated glass fibre post (everStick post) with composite core (Group C) and prefabricated zirconia posts with composite core (Group D). Control group (A) samples were selected with intact coronal structure. Post space was prepared in all samples. Two type of luting cements dual cure resin cement (Luxacore Z) and glass ionomer cement (Fuji I, GC) were used for post cementation. The core was standardized to 4mm × 5mm. Prepared samples were subjected to compressive load of 0.5mm/min at 135o angulation. The load at which fracture occurred and fracture mode were analysed statistically by one way ANOVA, post-hoc tukey test and chi-square test. Results: The findings showed statistically significant difference between failure loads. The mean load required to fracture glass fibre was highest (711MPa) and least for control group (231MPa). The glass fibre posts and zirconia posts showed favorable fracture. Conclusion: The results concluded that endodontically treated teeth without post core system showed least fracture resistance signifying need to reinforce tooth. Use of glass fibre post (everStick post) showed highest mean fracture resistance regardless of luting agent.

Survival of hollow metal post-retained restorations: A long term clinical follow-up

Abstract: Aim Aim of the research was to evaluate the long term results of an innovative system for the restoration of endodontically treated teeth. Material and methods A prospective evaluation was performed on 246 post and core build-ups. A total of 189 patients (57 lost) underwent clinical and radiological follow up from 1 up to 11 years. Tooth shape, post length and the presence of prosthetic crowns were recorded. Causes of failure considered were: root fracture, build-up detachment, restoration fracture, marginal infiltration and post fracture. The proposed restorative technique exploits the resin cement injection through a metal cylinder placed into the post space. The carrier was incorporated into the composite after polymerization. Results The statistical analysis showed how the global success rate of the technique is 96.8%. The failures were caused by marginal infiltration (2,65%) or core fracture (0.53%). The Cox regression shows that success is not related to post length (p=0.786) nor to the prosthetic crown (p=0.120). In the upper jaw the success was statistically related to the presence of the crown (p=0.47). Hazard ratio curves, related to the shape of treated teeth, underlined how premolars and molars are characterized by a higher risk of fracture when compared to incisors and canines. Log rank test does not gishowves any significant difference between the treated teeth. Conclusion The follow-up results highlighted a low incidence of failures of the procedure. The presence of prosthodontic crowns increases the success rate.

Intricate Estimation and Assessment of Surface Conditioning of Posts to improve Interfacial Adhesion in Post-core Restorations: An in vitro Study.

Abstract: INTRODUCTION Post and core restorations are routinely used for restoring grossly decayed tooth structures. Various chemical agents are known to affect the interfacial adhesions between the post and the core. Hence, we planned the present study to evaluate the effect of various post-surface treatments on the interfacial strength between the posts and composite materials that are used for building up the core portion. MATERIALS AND METHODS The present study included assessment of the effect of surface conditioning of posts on the interfacial adhesion in post-core restorations. A total of 80 clear post-tapers were included and were divided broadly into four study groups based on the type of chemical testing protocols used. Various chemical treatments included alkaline potassium permanganate, hydrogen peroxide, and phosphoric acid. The fourth group was the control group. The composite core material was used for building up the core. Testing of the tensile load was done on a universal testing machine. All the results were analyzed by the Statistical Package for the Social Sciences (SPSS) software. RESULTS The highest bond strength was observed in the study group treated with alkaline potassium permanganate, while the lowest was observed in the control group followed by the hydrogen peroxide group. While comparing the mean bond strength in between various study groups, significant results were obtained. CONCLUSION Chemical treatment protocol significantly alters the mean bond strength of the post and core restoration. CLINICAL SIGNIFICANCE Potassium permanganate significantly increases the bond strength between the fiber post and core restoration.

Esthetic rehabilitation of severely decayed primary incisors using glass impregnated fiber post as post and core: A treatment option

Abstract: Restoration of primary incisors, which have been severely damaged by extensive caries or trauma, is a difficult task for the pediatric dentist. Primary teeth dictate the physical appearance, and their structural affects leads to loss of esthetics compromised mastication, poor phonetics, development of aberrant habits, neuromuscular imbalance, and difficulty in social and psychological adjustment of the child. Case description: This case report discusses the restoration of severely decayed primary maxillary incisors using composite resin restoration reinforced with glass impregnated post in anterior teeth in a 4-year-old male patient. The use of intracanal posts in endodontically treated teeth improves the retention of a eventual restoration. The use of impregnated fiberglass post together with flowable composite offers an alternative where all components are bonded together to form a firmly attached restoration. This technique of glass impregnated composite resin post and core has shown promising results and has presented pediatric dentists with an additional treatment option.

Endodontic post and core retreatment –A case report

Abstract: Endodontic retreatment, when properly indicated, allows the maintenance of dental elements. The evolution of endodontic techniques and materials has reduced the indication of surgical procedures even for teeth with intracanal posts. Clinical Case-In the present report 28 year old patient reported with displaced post along with prosthesis. On radiographic examination there was extruded gutta percha in apical area. Treatment comprises of removal of gutta-percha followed by Post and Core.