Zirconia Posts Research Articles

Clinical Acceptance of Digitally Produced Zirconia and Metal Post and Cores, Based on the Impression Method.

The existing literature predominantly examines post and core assessments post-cementation, neglecting the critical pre-cementation phase. Research on the clinical acceptance of dental posts received from dental laboratories before cementation is notably lacking. This study investigates the percentage of zirconia and metal dental posts that are deemed suitable for cementation by clinicians, among the total received from the dental laboratory. Additionally, it aims to examine whether this percentage varies based on the type of impression made by the clinician: digital impression versus conventional impression. This article introduces the application of computer-aided design-computer-aided manufacturing (CAD-CAM) technology for manufacturing customized zirconia and Cobalt-Chromium (Co-Cr) post and cores. Intraoral scanning is employed to capture the canal anatomy. In contrast to the traditional casting process, a three-dimensional (3D) metal printer machine is utilized to 3D print the metal post and core from Co-Cr, resulting in enhanced toughness and superior adaptability to the canal. Two null hypotheses were formulated, investigating the clinical acceptance of zirconia and metal posts obtained through traditional versus digital impressions. Among 577 post and cores, 95% of metal posts from both impression methods received clinical approval. However, for zirconia posts, a significantly higher acceptance rate (95% versus 88%) was observed for those from traditional impressions. The Chi-squared test yielded a p-value < 0.05, underscoring the clinical superiority of conventionally obtained zirconia posts and supporting the null hypothesis for metal posts. A significantly higher acceptance rate is apparent among zirconia post and cores manufactured through conventional impressions, in contrast to zirconia post and cores produced via digital impressions. No statistically significant difference was identified between metal post and cores obtained through digital impressions and those acquired through conventional impressions.

Zirconia endocrown with intracanal extension and zirconia posts on maxillary molars: in silicio study.

The study aims to evaluate the stress distribution on tooth and restoration of zirconia endocrowns with pulp chamber or intracanal extension and zirconia post performed maxillary first molar using finite element analysis. Three three-dimensional endodontically treated maxillary molars were modeled. Cortical bone and cementum were modeled 2 mm and 200 μm in thickness. Periodontal ligament at 250 μm thickness was constructed. Zirconia endocrown with pulp chamber extension of 2 mm (Model E&#43;PCE), zirconia endocrown with intracanal extension of 4 mm (Model E&#43;ICE), and zirconia post of 4 mm and crown (ZP) were modeled using software. All restoration models were placed on the maxillary molars. Models were subjected to 400 N loading from the three occlusal contact points. Von Mises stress was recorded. Expectingly, points where the stress was applied showed high stress compared to other regions of the models. The stress did not occur at the trifurcation in any of the models. For the stresses occurring in the restoration material, there were 14.67 MPa, 57.79 MPa, and 155.56 MPa, in Models E&#43;PCE, E&#43;ICE, and ZP, respectively. At the remaining dentin, these values were 47.04 MPa, 32.85 MPa, and 33.42 MPa in Models E&#43;PCE, E&#43;ICE, and ZP, respectively. Within the limitation of the study, zirconia endocrowns with intracanal extension exhibit more favorable stress distribution in both restoration material and dentin compared to zirconia posts and pulpal extension endocrowns. These findings suggest that endocrown with intracanal extension may be a better restorative option for reducing stress.

The influence of zirconia and fiber posts with different lengths on the fracture strength of maxillary central incisors restored with zirconia crowns: an in vitro study.

Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of the present in vitro study was to estimate and compare the influence of the post length and type on the fracture strength of endodontically treated maxillary central incisors. Sixty extracted human maxillary central incisors were decoronated 2 mm above the cementoenamel junction. The teeth were selected and subjected to standard endodontic treatment, resulting in three groups with different preparation lengths: 5, 7.5, and 10 mm. Each group was randomly divided into two subgroups according to the post type: zirconia or fiber. After appropriate surface treatment, they were cemented with adhesive resin cement and restored with zirconia crowns. Thermocycling (5°C to 55°C, 60 s, 1500 cycles) was performed after cementing the zirconia crowns onto each tooth. Prepared samples were subjected to a compressive static load of 0.5 mm/min, at an angle of 130 degrees to the long axis of the roots, using a universal testing machine (Matest) at a crosshead speed of 0.5 mm/min, until fracture. The significance of the results was assessed using two-way analysis of variance (ANOVA) and the Tukey-Kramer test (α = 0.05). The ANOVA analysis indicated significant differences (P < 0.05) between the groups. The Tukey-Kramer test revealed no significant differences among the zirconia posts with lengths of 5 mm (26.5 N ± 13.4), 7.5 mm (25.2 N ± 13.9), and 10 mm (17.1 N ± 5.2). Also, in the fiber post group, there was no significant difference when the posts with lengths of 7.5 mm (13.4 N ± 11.0) were compared with those of 5 mm (6.9 N ± 4.6) and 10 mm (31.7 N ± 13.1). The 10-mm-long post displayed superior fracture strength, and the 5-mm-long post showed significantly lower mean values (P < 0.001). The fracture strength of zirconia posts (with lengths of 5 and 7.5 mm) was found to be significantly higher than that of fiber posts (with lengths of 5 and 7.5 mm). The 10-mm-long fiber post group demonstrated significantly higher fracture strength values, and the 5-mm-long fiber post group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P < 0.001). The fracture strength analysis with a universal testing machine is the only method that enables the estimation of the differences between zirconia and fiber posts with different lengths in endodontically treated teeth.

Canal disinfection using Nd: YAG Laser, synchronized microbubble-photodynamic activation, and carbon quantum dots on microhardness, smear layer removal, and extrusion bond strength of zirconia post to canal dentin. An invitro scanning electron microscopic analysis.

Evaluation of the impact of the latest root canal disinfectant, that is carbon quantum dots (CQDs), synchronized microbubble-photodynamic activation (SYMPA), and Nd: YAG laser along with ethylenediaminetetraacetic acid (EDTA) as a final irrigant on the Marten hardness (MH), smear layer (SL) removal, and extrusion bond strength (EBS) of zirconia post to the canal dentin. Eighty intact single-rooted premolars were obtained and disinfected using 0.5% chloramine-T solution. Root canal preparation was performed using ProTaper files followed by obturation. The post space was prepared for prefabricated zirconia post and all the teeth were randomly divided into four groups based on the disinfection used (n = 20 each) Group 1: 5.25% NaOCl + 17% EDTA (Control), Group 2: Nd: YAG laser + 17% EDTA, Group 3: SYMPA + 17% EDTA, and Group 4: CQDs + 17% EDTA. MH, SL removal, and EBS of zirconia post-bonded to root dentin were performed using a microhardness tester, scanning electron microscope (SEM), and universal testing machine, respectively. Both intragroup and intergroup comparisons were performed using one-way analysis of variance (ANOVA) and posthoc-Tukey test for significant difference (p < .05). Group 2 samples (Nd: YAG laser + 17% EDTA) (0.24 ± 0.06 GPa) exhibited highest values of MH. Samples in group 3 (SYMPA + 17% EDTA) treated teeth unveiled the lowest MH scores (0.13 ± 0.02 GPa). Moreover, the coronal third of Group 3 specimens (SYMPA and 17% EDTA) (1.54 ± 0.31) eliminated SL from the canal with the greatest efficacy as well as presented the highest EBS (10.13 ± 0.69 MPa). However, the apical third of Group 1 samples (5.25% NaOCl + 17% EDTA) (2.95 ± 0.33) exhibited the least efficient elimination of SL from the radicular dentin as well as the lowest bond strength (5.11 ± 0.19 MPa) of zirconia post to the dentin. The SYMPA technique with 17% EDTA proved highly effective in removing the SL from canal dentin and enhancing the EBS of zirconia posts. The least preferable method for SL removal and MH improvement was found to be 5.25% NaOCl + 17% EDTA. CQDs and Nd: YAG laser demonstrated satisfactory smear layer removal properties from the canal, along with achieving appropriate bond strength of zirconia posts. RESEARCH HIGHLIGHTS: Nd: YAG laser and 17% EDTA as canal disinfectant exhibited the highest values of MH. Specimens irrigated with SYMPA and 17% EDTA eliminated SL from the canal with the greatest efficacy. The coronal third of Group 3 (SYMPA + 17% EDTA) samples unveiled the highest zirconia post-bond integrity score to the canal dentin. Cohesive failure was a dominant failure type among different experimental groups.

NEW CONCEPT OF FRONTAL TEETH RESTAURATION FOR EXCELLENT FUNCTION AND AESTHETIC

This clinical case report aimed to investigate impact of a novel inner ferrule (IF) preparation around root canal on the subsequent esthetic restoration. Material and Methods: This clinical research involved a case report featuring endodontically treated teeth (ETT) restored using a newly developed ceramic post. Special drills (Edenta AG GmbH, Switzerland) were utilized for root canal preparation, involving horizontal preparation around the cervical portion of the root canals and post spaces. Experimental samples (ETT) were prepared with and without a 2mm IF preparation. The newly designed zirconia ceramic posts (TZ-3Y-SBE, Tosoh, Japan) were cemented with Multilink Automix (Ivoclar), upgraded with MultiCore (Ivoclar), and crowned with an all-ceramic zirconia crown (Zirkonzahn, Italy). Results: Our clinical case provided insights into a new type of all-ceramic aesthetic restoration of prepared teeth (ETT) with a new IF preparation design and a new zirconia post-core design. Conclusion: The novel horizontal IF preparation around the root canal was developed to accommodate the initial retentive coronal ring of the newly designed zirconia posts. The incorporation of IF preparation and coronal retentive rings within the zirconia post structure effectively enhances the fracture resistance of ETT. This new modern aesthetic rehabilitation in all restored teeth significantly reduces the severity of root fractures for excellent function and aesthetic restoration of ETT.

In Vitro Evaluation of Push-Out Bond Strength in Three Different Post Systems

Background and objectives: Intimate adaptation to the canal walls is accomplished by custom-made posts which leave an even thickness of cement layer. Therefore, this study has been conducted for assessing the strength of push-out bond among prefabricated fiber posts, relined fiberglass posts, and zirconium posts using resin cement of self-adhesive and adhesive. The mode of failure was also assessed. Materials and Methods: Sixty uniradicular teeth were endodontically treated. According to the kind of post system and cement utilized (n=10), the specimens were separated randomly into six groups. Zirconium oxide post, customized glass fiber post, and glass fiber post were used. The roots were divided into three discs: apical, middle, and cervical sections. After that, the discs were put through a push-out test, and the fracture mode was examined using a stereomicroscopic loupe. Results: The highest push-out value was recorded for the relined post (8±2.83 MPa), and the lowest was registered with no significant differences for the prefabricated post (7.27±3.76 MPa). There were no significant differences in strength bond across the various posts and root regions (P?.05). Adhesive failure at the dentin-cement interfaces for the prefabricated and relined post was (60, 57) % respectively, and zirconium oxide post was (22%). Conclusions: Relined posts may be a suitable clinical situation as a post material selection with reduced clinical steps. When posts are joined using self-adhesive and adhesive resin cement, the root region has no important influence on the strength of the bond.

Evaluation of Fracture Resistance of Endodontically Treated Teeth with Two Different Post System: An In-Vitro Study

Background: The number of endodontic procedures has increased steadily in the past decade with highly predictable results. Therefore, restoration of teeth after endodontic treatment is becoming an integral part of the restorative practice in dentistry. When restoring an endodontically treated tooth, the first step is to assess the level of predictability involved in the restoration. Proper restoration of ET teeth begins with a good understanding of their physical and biomechanical properties, anatomy, and a sound knowledge of the endodontic, periodontal, restorative and occlusal principles. A thorough understanding of posts is necessary to make the right selection, as there are so many choices available. Finally, the choice of core material and the final restoration are important in achieving long-term clinical success. Aim: To compare the fracture resistance of endodontically treated teeth restored with two different post-core systems. Material and Method: The samples were split into two groups of 15 each and given root canal therapy on 30 maxillary incisors. For two experimental groups, post space preparation and tooth restoration utilizing glass fibre posts with composite cores and adhesive resin cement (Group A) and zirconia posts (Group B) respectively were carried out.. Using the universal testing apparatus, 0.5 mm/min of force was applied to each sample at 130 degrees until fracture was experienced. A statistical analysis of the data was done after measuring the fracture resistance. Result: The least fracture resistance was found in Group A (Glass Fibre Post). Additionally statistically more significant than groups A and B was group B (Zirconia Post). According to the statistics that were found, the p value is significant (p&lt; 0.05). Conclusion: The load needed to fracture the custom-made zirconia post was higher than that of the glass fibre post, according to the study's limitations.

Use of final irrigants MTAD, Salvedora Perscia, Malachite green, and Ti-sapphire laser on push-out bond strength of Zirconia post

AIM: Evaluation of the push-out bond strength (PBS) of zirconia post-bonded to radicular dentin after using different final irrigants (MTAD, Malachite green (MG), Ti-sapphire laser and Salvadora persica (S.persica). MATERIAL AND METHOD: Forty human permanent single-rooted were decoronated above the cement-enamel junction. An experienced endodontist performed all the root canal instrumentation using ProTaper universal rotary files. Canals were irrigated using 5.25% NaOCl solution followed by EDTA as a final sterilant. Obturation with gutta-percha using AH Plus sealer was performed. Post-space preparation was completed using Gates Glidden and specimens were randomly assigned to four groups based on the final disinfectant received (n=10). Group 1: 5.25% NaOCl + MTAD, group 2: 5.25% NaOCl + MG, group 3: 5.25% NaOCl +Ti-sapphire laser, and group 4: 5.25% NaOCl + S. persica. The chemically polymerized resin was used to lute zirconia posts. PBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40X magnification. Data were compared between the two groups with 95% CI using one-way analysis of variance (ANOVA) with the Tukey post hoc test. p=0.05. RESULTS: Group4(5.25% NaOCl+ S.persica) specimens demonstrated the maximum (8.94±0.14 MPa) bond strength. Conversely, the apical third of Group 2 (5.25% NaOCl+ MG) (2.87±0.15 MPa) samples revealed the minimum bond strength scores. Intergroup comparison exposed that Group 1 (1.3% NaOCl+ MTAD), Group 3 (5.25% NaOCl+Ti-sapphire laser), and Group 4 (5.25% NaOCl+ S. persica) at all three-thirds unveiled no significant difference in PBS (p<0.05). CONCLUSION: Ti-sapphire laser and Salvedora Persica possess the potential to be used as a final root canal irrigant to improve the push-out bond strength of zirconia post-to-root dentin.

Use of final irrigant potassium titanyl phosphate laser; Sapindus Mukorossi and Fotoenticine on the bond values of zirconia post-to-canal dentin

AimsAssessment of the efficacy of final root canal irrigants Sapindus mukorossi (SM), Potassium titanyl phosphate laser (KTPL), and Fotoenticine (FTC) on the push-out bond strength (PBS) of zirconia post. Materials and methodsThe root canal procedure was initiated using the 10 K file and the working length was determined on single-rooted human premolar teeth after decoration. The canals were then enlarged using ProTaper universal system and filled using single cone gutta-percha (GP) and AH Plus resin sealer. Post space was prepared by removing 10 mm of GP from the canal. All the teeth were then allocated into four groups based on the final irrigating regime used (n = 10) Group 1: 5.25% NaOCl+17% EDTA, Group 2: 5.25% NaOCl + KTPL, Group 3: 5.25% NaOCl + FTC and Group 4: 5.25% NaOCl+ SM. Zirconia posts were cemented in the canal space. The specimens were sectioned and implanted in auto-polymerizing acrylic resin. A universal testing machine and stereomicroscope at 40x magnification were used for PBS and failure mode analysis. ANOVA and Tukey post hoc test were used to make group comparisons(p = 0.05). ResultsGroup 4 (5.25% NaOCl+ SM) coronal section displayed the highest PBS (9.29±0.24 MPa). However, group 3 (5.25% NaOCl+ FTC) apical third (4.08±0.14 MPa) showed the lowest bond values. Group 2 (5.25% NaOCl+ KTP laser) and Group 3 at all three-thirds unveiled no significant difference in PBS(p>0.05). However, Group 1 (5.25% NaOCl+17%EDTA) and Group 4 displayed comparable outcomes of bond strength(p>0.05) ConclusionSapindus mukorossi has the ability to be used as a final root canal irrigant alternative to EDTA. However, future studies are still required to conclude the outcomes of existing research.

In-Vitro Effect of Effectively of G-Bond and Z-Prime Plus in Prevention of Fracture of Prefabricated Zirconia Posts Bonded to Root Canal Walls

Background and Aim: The purpose of this research was to examine the influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals. Place of Study: Avicenna Medical College Lahore Study Duration: March 2021 to April 2022 Materials and Methods: In this in-vitro experimental study, the diameter and length of each of the 20 mandibular premolars used were identical. This assured that the study's findings were comparable. Once a cut was made at the cementoenamel junction (CEJ) to prepare the teeth for root canal therapy, the teeth were randomly assigned to one of two groups (n=11) with the same number of teeth in each group. In the experiment, a single tooth from each group was chosen at random to serve as the control. A post space of approximately 10 millimeters in length was established in the remaining teeth. The following process involved etching the intracanal dentin, followed by rinsing and drying the material. The technique involved filling the canal with Panavia F2 resin cement. After applying G-Bond and Z-Prime Plus to the zirconia posts in respectively, groups 1 and 2, the placement of post was done in the canals and subsequently cemented. The photo core resin composite material was utilized in the fabrication of the cores. The longitudinal axis of the teeth was compressed by a force application to the core of central fossa o at a crosshead speed of 0.5 millimeters per minute. This was accomplished with a crosshead speed of 0.5 mm/min. The load that caused the fracture was measured and documented. To analyze the data, a t-test was conducted, and a normal distribution was also taken into account. Result: The results indicated that the average fracture resistance of G-Bond was 1088.1±330 while the average fracture resistance of Z-Prime Plus was 898.4±369 however, the difference was not statistically significant (P=0.3). Practical Implication: The influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals Conclusion: There was no significant difference between the fracture resistance of zirconia posts bound with G-Bond and Z-Prime Plus to root canal walls. In contrast, G-Bond is highly advised for usage in this application due to its decreased coefficient of variation (CV) and significantly increased fracture resistance. This makes it a great option for the current endeavor. Keywords: Primer; resin composite; shear bond strength; zirconia ceramic, G-Bond, Post and Core Technique, Z-Prime Plus

Bond strength of various post-core restorations with different lengths and diameters following cycle loading

PurposeThis in vitro study aims to evaluate the bonding strengths of Polyether ether ketone (PEEK), Polyether ketone (PEKK), Fiber, and Zirconia (ZrO2) post-core restorations with posts in different diameter and length following chewing simulator. Materials and methodsEndodontic treatment was performed on 256 intact maxillary central teeth. The test specimens were prepared in four groups according to the types of materials: Glass fiber post-composite core (FB-n:64), Zirconia post-core (Zr-n:64), PEEK post-core (PE-n:64), and PEKK post-core (PK-n:64). The groups were divided into four subgroups according to diameter and length (n:16): Group 1: 10 mm length 1.75 mm diameter, Group 2: 10 mm length 1.5 mm diameter, Group 3: 7 mm length 1.75 mm diameter, Group 4: 7 mm length 1.5 mm diameter. Custom PEKK, PEEK, Zirconia post-cores, and Zirconia crowns were milled on the CAD/CAM. The post-cores and crowns were cemented to the teeth with dual-cure resin cement. After that, all subgroups were divided into control and cyclic loading groups. During the cycling, the control test group was kept in distilled water at 37±1oC before the push-out test. Half of the specimens were loaded with 250,000 cycles and 50 N with a chewing simulator. All test specimens had 1.5 mm sections taken from their roots. Then, the push-out test was applied to these sections for bond strength. Data were analyzed by Mann-Whitney U test, Shapiro-Wilk, Kruskal-Wallis's test, and Chi-Square. The statistical significance level was determined as 0.05. ResultsThe bond strength of all test groups decreased after the cycling loading. The bond strength values of zirconia posts showed a statistically significant difference (p < 0.05). The 10 mm length 1.75 mm diameter posts made of Zirconium had the highest bond strength observed in all control and cyclic loading groups of test specimens (9.74 MPa-6.25 MPa). The PEEK test specimens with a 7 mm length and 1.75 mm diameter showed the weakest bond strength in all control and cyclic loading groups (5.44 MPa-3.37 MPa). The average of the cervical region's bond strength values was statistically significantly higher than the apical region (p < 0.05). ConclusionWithin the limitations of this study, one-piece custom-milled Zirconia post-cores appear promising, as they perform well under functional forces, especially in the anterior region. In addition, custom-milled PEKK post-cores might be considered a suitable alternative to prefabricated fiber-reinforced posts.

Three-Dimensional Finite Element Study of Endodontically Treated Maxillary Central Incisors Restored Using Different Post and Crown Materials.

Restoring endodontically treated teeth is a common problem in dental practice. Post and core restorations are one of the major options in the rehabilitation of these teeth. However, there is no final decision regarding the best material or technique to be used with these restorations. So, this study aimed to evaluate the effect of different post and crown materials on the biomechanical behavior of restored maxillary central incisor using the finite element method. A total of 10 3D models of endodontically treated maxillary central incisors restored with two prefabricated posts and three custom-made posts were modeled and grouped according to post material (gold, nickel-chrome, zirconia, and glass fiber) and crown material (lithium disilicate, and zirconia). Finite element analysis was conducted, and stress distribution was evaluated using von Mises criteria. Both crown materials showed stress concentration at the force application site mainly on the intaglio palatal surface of the crown. However, more stress values were observed within zirconia crowns. All posts showed stress concentration at their buccal sides. However, more stress values were observed in zirconia and metal cast posts compared to glass fiber posts that transfer more stress to root dentin. Post and crown materials affect the stress distribution in the tooth-restoration complex. Using high elastic modulus posts slightly decreased stress in root dentin despite concentrating more stress within their structure. However, glass fiber posts resulted in more homogenous stress distribution in the tooth-restoration complex. Crown material did not influence the stress distribution in root dentin. Custom-made posts decreased stress within crowns, regardless of the crown material. However, more stress values were observed within zirconia crowns. Custom-made zirconia posts and cores showed a similar stress distribution as non-precious metal cast posts, so they may be used as a suitable option where esthetic is desirable.

Fracture Resistance of Cast Metal and Zirconia Posts on Endodontically Treated Teeth: An in Vitro Study

Background: ETT are widely considered to be more susceptible to fracture than vital teeth and require specialized restorative treatment. The aim of this study was to estimate and compare the fracture resistance (FR) of Endodontically treated teeth (ETT) restored with cast metal posts (CMP) and zirconia posts (ZP) with Universal Testing Machine (UTM). Methods and Results: A total of 60 intact canines extracted for periodontal reasons were selected for the present study. The tooth samples were randomly divided into 2 groups based on the post type used for restoration. Group 1 tooth samples (n=30) were restored with CMP. Group 2 tooth samples (n-30) were restored with ZP. All the samples were subjected to compressive load using a UTM at a cross-head speed of 0.5mm/min on the palatal slope at an angle of 135° to the long axis of the tooth. The maximum load necessary to fracture for each specimen was measured in Newtons (N). The results obtained showed that the difference in FR means between CMP and ZP was statistically significant (P&lt;0.0001). Conclusion: The FR of ZP was found to be significantly higher than those of CMP. The FR analysis with UTM is the only method that enables us to estimate the differences between the ETT restored with CMP and ZP.

Effects of different surface treatments on the compression-shear strength of CAD-CAM zirconia posts

Aim: Post systems are crucial for the treatment of endodontically treated teeth with excessive crown destruction. Currently, increase in esthetic demands has increased the use of tooth-colored post systems. The aim of this study was to evaluate compression-shear strength after the application of different resin cements and different surface treatments to zirconia post-cores produced by the CAD-CAM milling technique. Methodology: One hundred twenty crown parts of maxillary central incisors were cut using a 2-mm enamel–cement joint using a water-cooled diamond bur in an air turbine handpiece at 300,000 rpm. Root canals with the same diameter were prepared using Gates-Glidden drills and Snowpost system drills. According to the enlarged canal, zirconia posts were prepared by the CAD-CAM copy-milling technique, and the zirconia post surfaces were roughened by different techniques (hydrofluoric acid, Al2O3 partial abrasion, CoJet silica coating). The roughened posts were cemented to the tooth canal using three resin cements: 10-Methacryloyloxydecyl dihydrogen phosphate (MDP)-containing cement, Bis-GMA-based resin, and resin-based adhesive. As the control group, the zirconia post surfaces with no application were fixed using three resin cements. The specimens were set down into 25x25x25 mm fabricated blocks with acrylic resin materials. Compression-shear strength tests of the prepared samples were conducted on the Instron Testing Machine by using appropriate equipment. Results: In summary, the combination of roughening techniques such as Al2O3 partial etching and CoJet silica coating using cement-containing MDP rendered the highest compression-shear strength. Conclusion: This in vitro study proposes the cementation of zirconia post-cores etched by Cojet silica coating and Al2O3 particles using MDP-containing resin cement. How to cite this article: Eskitaşçıoğlu M, Toprak Gündüz D, Seyfioğlu Polat Z, Göncü Başaran E, Ayna E. Effects of different surface treatments on the compression-shear strength of CAD-CAM zirconia posts. Int Dent Res 2022;12(2):55-61. https://doi.org/10.5577/intdentres.2022.vol12.no2.a3 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Fracture resistance of maxillary premolars restored with different endocrown designs and materials after artificial ageing.

To evaluate the effect of three different designs and two monolithic ceramic materials on the durability and fracture resistance of endocrowns on maxillary first premolars, in comparison to post-and-core crowns. Fifty-six maxillary premolars were endodontically treated and shortened to a level of 2 mm from the cervical line, and randomly categorized into six endocrown groups and post-and-core crown control group (n=8); E1; endocrowns with flat occlusal table (without ferrule), E2; endocrowns with 1.5 mm circumferential ferrule, E3; endocrowns with 1.5 mm buccal ferrule preparation. Two materials were used for endocrowns: zirconia (4YSZ; Z), and lithium disilicate (L). The control group was restored with zirconia posts, and lithium disilicate crowns. All restorations were bonded using Panavia V5 and its respective primers and underwent thermo-mechanical fatigue with a 10 kg dynamic load for 1,200,000 cycles and thermocycling between 5 and 55 °C. Thereafter all survived specimens were loaded to fracture. The results were statistically analyzed using ANOVA and T-Test. None of the specimens showed any signs of debonding or fracture caused by the fatigue test. The PC control group showed no statistically significant difference in comparison to groups ZE1, ZE2 and LE2 (p > 0.05). However, it was significantly different from groups LE1, LE3, and ZE3 (p ≤ 0.05). Preparation designs and materials affected the fracture resistance of endocrowns. The results showed a superiority of the post-and-core crowns, zirconia/lithium disilicate endocrowns with 1.5 mm circumferential ferrule, and zirconia endocrowns with the flat occlusal table.

Finite Element Stress Analysis of PEEK, Glass Fiber and Zirconia Post-Core Sys-tems in Maxillary Central Incisor

Objective: This study aims to analyze structural strength features (such as deformation and stress distributions) of polyether ether ketone (PEEK), glass fiber and zirconia post-core systems utilized in maxillary central incisor roots by means of finite element analysis (FEA).&#x0D; Material and Method: The main geometry of maxillary central incisor considered in this study was obtained using an intraoral scanner. Other sub-components were modelled in a parametric computer aided design software based on the data obtained from the literature. Glass fiber, PEEK and zirconia were defined as post materials. 100 N force was applied with 45° angle on the palatal surface of veneered tooth in the FEA set up. The FEA was solved with linear material model and static linear loading assumptions through a commercial FEA code. Visuals and numerical results related to equivalent stress (Von Mises) and deformation distributions were interpreted.&#x0D; Results: Maximum equivalent stress value of 32.76 MPa was calculated at the PEEK post-core. The maximum values for glass fiber and zirconia posts were 0.80 MPa and 21.17 MPa, respectively. Maximum equivalent stress values at the tooth roots in the glass fiber, zirconia and PEEK posts were 72.79 MPa, 69.01 MPa and 58.22 MPa respectively.&#x0D; Conclusion: The stress magnitude experienced at the PEEK post-cores on the root was lower than glass fiber post and zirconia post. Regarding to this, although, it may be concluded that PEEK may reduce the complications that require tooth extraction in clinical practice, further researches are suggested including clinical trials.

Comparison of the fracture strength of endodontically treated teeth restored with polyether ether ketone, zirconia and glass-fibre post-core systems.

This study aimed to compare the fracture resistance and fracture mode of maxillary central incisors restored with four different sizes and three different post-core systems. One hundred and twenty maxillary incisors were endodontically treated and randomly divided into three groups (12 subgroups). Post cavities for the narrow subgroups were prepared with 1.4-mm-diameter drills in lengths of 7.5mm (SN) and 10mm (LN). Post cavities for the wide subgroups were prepared with 1.6-mm-diameter drills in lengths of 7.5mm (SW) and 10mm (LW) (n=10). Group F was restored with glass-fibre post and composite resin core, Group P was restored with custom PEEK post-core and Group Z was restored with custom zirconia post-core. All posts were cemented with a dual-cure resin cement. Zirconia copings were cemented. Specimens were loaded on the palatal surface with a universal testing machine, and the fracture strengths of the teeth were statistically analysed using ANOVA and post hoc Tukey tests. Statistically significant differences existed between the fracture strengths of the post materials. The highest fracture strength was in Group F, and the lowest was in Group P. Evaluation of the fracture strengths of the post lengths and diameters demonstrated that the short-narrow group of Group Z had the lowest fracture strength (P<.05). The long-wide group of Group F showed the highest fracture resistance. In Group P, no statistically significant difference existed between the post-cores of different dimensions (P>.05). Irreparable fractures were observed mostly in Group Z, and decementation was more common in Group P. PEEK post-cores showed sufficient fracture strength for the anterior region, similar to the other two post-core materials. PEEK post-cores showed more decementation and repairable fractures at lower forces, while restoration failure was mostly catastrophic for glass-fibre and zirconia posts.

Effect of Nd:YAG, Er,Cr:YSGG Laser Irradiation, and Adjunctive Photodynamic Therapy on Push-Out Bond Strength of Zirconia Posts to Radicular Dentin.

This study is aimed at assessing the influence of Nd:YAG, Er,Cr:YSGG laser irradiation, and adjunctive photodynamic therapy (aPDT) on the bond strength of zirconia posts to radicular dentin. Eighty extracted anterior teeth were randomly categorized into 4 groups (n = 20) based on varying laser irradiation treatments, i.e., conventional cleaning and shaping (CCS), Nd:YAG, Er,Cr:YSGG, and aPDT group, respectively. Using a cutting machine, the samples were prepared for push-out bond strength analysis; 4 sections (2 on each apical and cervical) of around 1 mm thickness were sectioned for all roots at a right angle to the long axis of the post. After making the space for the post, they were incorporated into the root system and were subjected to different laser treatments. The universal testing machine was utilized to assess the push-out bond strength, which had a defined 1 mm/minute crosshead speed until the failure was encountered. Specimens in the aPDT group (8.20 ± 2.14 MPa) demonstrated the highest mean push-out bond strength, whereas the lowest was shown by samples in the CCS group (7.08 ± 1.11 MPa). According to the independent t-test, the mean push-out bond strength scores of the cervical segments were higher as compared to the apical segments in research groups (p < 0.05). Overall, the adhesive type was the most frequently encountered failure mode in all of the experimental groups, with the least number of failures observed in aPDT treated teeth samples. In conclusion, the push-out bond strength to radicular dentin was not much influenced by Nd:YAG, Er,Cr:YSGG laser, and aPDT in comparison with CCS. Although statistically not significant, however, the application of aPDT provided better outcomes as compared to other research groups.

Influence of dental crown topography on fracture resistance of premolars with MOD preparation and subjected to different restorative protocols.

To evaluate whether dental crown topography influences the fracture resistance of premolars treated endodontically and with MOD preparation subjected to different restorative protocols. Sixty-four human premolars with one or two roots in equal numerical proportions (n) were selected and randomly divided into four groups (n = 8): (S = single-rooted; D = double-rooted) SS: sound single-rooted; SNR: endodontics (E) + MOD cavity preparation; SR: E + MOD + resin restoration (RS); SP: E + MOD + RS + horizontal zirconia post (ZP); DS: sound double-rooted; DNR: E + MOD; DR: E + MOD + RS; and DP: E + MOD + RS + ZP. After allocation to the groups, the samples were thermocycled and then subjected to the fracture resistance test. Failures after the fracture test were classified as irreparable (with pulp floor fracture) or reparable (without pulp floor fracture). Data were analysed using one-way anova and the Tukey test (α = 0.05). Single-rooted premolars were more resistant to fracture than double-rooted premolars. The restorative treatment using a horizontally transfixed zirconia post improved fracture resistance, resembling that of a healthy tooth.

Stress distribution of esthetic posts in the restored maxillary central incisor

Glass fiber posts, along with their esthetic properties, may have a better stress distribution than cast posts, Therefore, the aim of the present study was to investigate the effect of glass fiber, casting, titanium, and zirconia posts on stress distribution in maxillary central tooth treated with different amounts of ferrule using finite-element analysis. In this experimental study, three-dimensional models of maxillary central incisors that have undergone root canal treatment were designed. Then, the models were divided into four groups according to the type of post (Ni-Cr casting, glass fiber, titanium, and zirconia) used. Zirconia monolithic crowns were used in all the four groups. Ferrule heights were repeated at 0 and 2 mm in all models. Models were entered into COMSOL Metaphysics software. Then, the force of 100 N with the angle of 135° on the palatal surface was applied to the longitudinal axis of the tooth, and the stress distribution in the models was investigated. Maximum stress was observed in the middle third of posts. Stress distribution in glass fiber post was better than zirconia and casting posts. Stress accumulation in models with zirconia, titanium, and casting posts was also found in the site between the middle third and coronal third, whereas in models with glass fiber post, stress accumulation was found between the crown and the cemento-enamel junction. In models without ferrule, stress accumulation was observed in one-third of the coronal, especially in glass fiber posts. The post material and ferrule height affected stress concentration. The stress in the cervical area of the dentin was more for glass fiber post when compared to other posts. The use of glass fiber post in teeth with no ferrule results in lower stress along the post, but greater stress in the simulated tooth region.