Human Maxillary Premolars Research Articles

Effect of irrigation protocols for post space preparation on the bond of the resin luting agent and post to a hydraulic calcium silicate filled root: An in vitro study.

The hydraulic calcium silicate-based sealers (HCSSs) used in endodontic treatments have been reported to interfere with the bond of the post to root canal dentin. Post space irrigation plays a significant role in optimizing the bond, but which protocol is effective for cleaning HCSS-smeared intraradicular dentin is unclear. The purpose of this in vitro study was to evaluate the effect of passive ultrasonic irrigation (PUI) as an adjunct to different irrigation protocols, including with ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX), and sodium hypochlorite (NaOCl), and root regions on the push-out bond strength of a self-etch primer-assisted resin luting agent adhered a post to root canal obturated with hydraulic calcium silicate sealer. The palatal root of 60 human maxillary premolars were shaped and obturated with gutta-percha and HCSS (iRoot SP). The post space was prepared using a peeso reamer and double taper drill, and the specimens were divided into 6 groups (n=10) according to the following irrigation protocols: distilled water with conventional syringe, distilled water with PUI, 17% EDTA with PUI, 2% CHX with PUI, 17% EDTA + 2.5% NaOCl with PUI, and 17% EDTA + 2% CHX with PUI. Fiber-reinforced posts (DT Light-Post) were cemented with dual-polymerizing resin luting agent with self-etching primer (Panavia V5). Specimens underwent 6000 thermocycles, were sectioned into 3 slices, and were tested for push-out bond strength and failure mode. The 2-way mixed ANOVA, Kruskal-Wallis H, Dunn post hoc, and chi-squared tests were used for statistical analysis (α=.05). The PUI/EDTA/NaOCl group exhibited significantly higher push-out bond strength than irrigation with distilled water, whether incorporated with PUI or not (P=.001 and P=.007, respectively). The root region showed no statistical effects on bond strength (P>.05). The irrigation protocol was significantly associated with failure mode (P=.049). PUI with EDTA/NaOCl followed by distilled water improved the bond strength of self-etch primer-assisted resin luting agent and fiber-reinforced post to an HCSS-obturated tooth. Alternative irrigation protocols did not significantly enhance bond strength.

Fracture resistance and behavior of endodontically treated maxillary premolars with varying ferrule heights and post numbers: A laboratory study.

To investigate how varying ferrule heights and the number of glass fiber posts affect fracture resistance and behavior of endodontically treated maxillary first premolars with substantial loss of tooth structure. Twenty-four extracted endodontically treated human maxillary first premolars were divided into three groups (n=8) based on ferrule height and post number. The groups were as follows: premolars of 2mm ferrule height that were restored with single posts (control group), premolars of 0.5mm ferrule height that were restored with single posts in palatal canals (single-post group), and premolars of 0.5mm ferrule height that were restored with double posts in palatal and buccal canals (double-post group). All groups were then restored with composite core and metal-ceramic crowns cemented with zinc phosphate cement. All specimens were subjected to 10,000 thermal cycles at temperatures of 5°C and 55°C, as well as 1.2 million cyclic loadings of 49N load at 1.2Hz using a chewing simulator. The specimens were loaded to fracture in a universal testing machine and fracture behavior was examined under stereomicroscope and divided into restorable and unrestorable fracture modes. Fracture loads and modes were analyzed by one-way ANOVA, Tukey's post hoc test, and Fisher's exact probability test (p≤0.05). The control group showed the highest mean fracture load (1127±172) of all groups (p<0.001). The specimens in the single-post group showed numerically higher mean fracture load (522±171) but with no significant difference compared to the ones in the double-post group (518±157; p>0.967). In the control group, 75% of specimens showed unrestorable fractures compared to 50% and 12.5% in single-post and double-post groups. The specimens in the control group had similar unrestorable fractures, starting from the coronal part and extending obliquely to the cervical third of the root below resin level. Two specimens in the control group showed unrestorable fractures in the middle third of the root. No middle-third root fractures were observed in single-post and double-post groups, and unrestorable fractures in both groups were similar to those of the control group. The single-post group had two specimens with core-post crown complex restorable fractures, while the control and double-post groups had one specimen each. The remaining specimens showed cervical-third root restorable fractures above resin level. The ferrule height significantly influences the fracture resistance of endodontically treated premolars compared to the number of placed posts. Nonetheless, more restorable fractures are seen in endodontically treated premolars restored with double posts than single posts regardless of ferrule height.

An in vitro study on comparative evaluation of shear bond strength of bioactive composite to tooth structure with various dentin conditioning agents

Bioactive materials are an alternative to conventional restorative materials, which have been promising and challenging at the present time. Etchants or bonding agents are not required as this bioactive material chemically binds to teeth. A potent resin hydroxyapatite complex is formed due to ionic interaction, further preventing microleakage. Applying citric acid and maleic acid is an added advantage in removing the formed smear layer during cavity preparation. This study uses various bonding and conditioning agents to evaluate the strength of bioactive composite shear bonds to the tooth structure. Sixty extracted human maxillary premolars were collected for this study. They were randomly divided into four groups. They were treated with their respective conditioning and bonding agents. The Statistical Package for Social Science software version 23 by IBM was used for data processing and analysis. All p-values less than 0.05 were considered statistically significant. The highest mean bond strength was recorded for the self-etch adhesive group (27.54 MPa), followed by the phosphoric acid group (23.77 MPa), maleic acid group (23.11 MPa), and control group (19.21 MPa). A comparison of intergroup mean bond strength was made using one-way ANOVA. 52.36 was the sum of squares between groups, and that within the group was 19.984, with a degree of freedom between groups being 3 and that within the group being 56, which was statistically significant. The post hoc Tukey test was used for individual group interaction, which was statistically significant. The bond strength of the Activa-restorative material was increased by the pre-conditioning tooth surface. G-bond self-etch adhesive showed the highest efficacy in improving the bond strength among other agents.

Fracture Resistance of Different Monolithic Zirconia Crowns with Horizontal and Vertical Finishing Lines: A Comparative in Vitro Study

Objective: The primary objective was to examine how different preparation techniques and zirconia materials affected fracture strength. Materials and methods: 48 sound human maxillary first premolars of similar shape and size were used, categorized into two main groups of 24 teeth, as per the preparation technique: Group A: chamfer preparation design. Group B: vertical preparation design. Then, based on the type of material, each main group was subcategorized into three subgroups of eight teeth: IPS emax Zircad LT, IPS emax MT and IPS emax Prime (IvoclarVivadent). All the samples, prepared by the same operator, with the assistance of a dental surveyor. Intra-oral scanning was performed on the prepared teeth. The SironaInLab CAD 20.0 software was used to design crowns and were subsequently generated using a 5-axis milling machine. Self-adhesive resin cement was used to bond crowns to their respective teeth. To assess the crown's fracture strength, a computer-controlled universal testing system was used, which records the fracture strength automatically in each sample in Newton (N) during a single load-to-failure test. Burke's classification was employed to assess the fracture mode by analyzing each sample under a 40x digital microscope. The collected data were evaluated using statistical analysis using the independent t-test and ANOVA, with a 0.05 significance level. Results: Vertical preparation technique had higher fracture strength than the chamfer preparation technique with a statistically significant difference (p &lt; 0.05). While comparable fracture resistance was identified across various monolithic zirconia crowns. All samples demonstrated a severe fracture of the crown and/or tooth (Code V). Conclusion: The vertical preparation design illustrated significantly better fracture strength than the chamfer preparation design, Materials comparisons showed comparable fracture resistance.

Colloidal platinum nanoparticles enhance resin-dentin bonding durability

This study aims to investigate the effect of colloidal platinum nanoparticles (CPN) on the durability of resin-dentin bonding performance with contemporary adhesives. Sixty non-carious human maxillary premolars were subjected to microtensile bond strength (µTBS) testing and divided into two main groups: CPN-treated and untreated. Within each group, specimens were randomly allocated to Clearfil Megabond 2 (MB2), Scotchbond Universal Plus Adhesive with self-etch mode (SE-SUP), and etch-and-rinse mode (ER-SUP) subgroups (n=10/group). CPN was applied to dentin in the MB2 and SE-SUP groups for 20s, followed by rinsing before adhesive application. In the ER-SUP group, CPN was applied after etch-and-rinse. The µTBS was tested after 24h, 6 months, and 1 year, and the fracture modes were observed using SEM. The µTBS data were analyzed using a two-way ANOVA and post-hoc Tukey HSD test (α=0.05). An additional twelve premolars underwent TEM/STEM/EDX for ultra-morphological observations. The application of CPN significantly prevented a decline in the µTBS of both the MB2 and SE-SUP groups. No significant decrease was observed in the ER-SUP group, either with aging or CPN application. Ultra-morphological images revealed platinum nanoparticles attaching to the collagen fibrils of the hybrid layer regardless of aging. It was highlighted that the nanoparticles attached to the banded collagen in the aging groups were observed. CPN exhibits the potential in enhancing the longevity of resin-dentin bonding in SE mode.

Root Canal Morphology of Premolars in Population of Hyderabad, Pakistan: A Cone Beam Computerised Tomographic Analysis.

To investigate the mean tooth length and root canal configuration of human maxillary and mandibular premolars in the population of Hyderabad, Pakistan, using Cone Beam Computed Tomography (CBCT). Observational study. Place and Duration of the Study: Department of Operative Dentistry and Endodontics, Liaquat University of Medical and Health Sciences, Jamshoro, Sindh, Pakistan, from December 2022 to March 2023. Using retrospective analysis of CBCT scans, tooth length, the number of roots, and root canal configuration of 536 mandibular and maxillary premolars were assessed in the subpopulation of Pakistan. The data were analysed employing descriptive statistics, Chi-square tests, and One-Way ANOVA to determine the association between various factors and root canal morphology. Vertucci Type 1 (one canal) was the most common configuration in maxillary premolars, with frequencies ranging from 46.3 to 52.2%. The mean length of all 8 premolars ranged from 20.56 mm to 21.58 mm. C-shaped canal configurations were observed in a small percentage of maxillary and mandibular premolars, with C1 being the most common. No significant association was found between gender and canal configuration or tooth length, and in tooth lengths among different canal configurations. Vertucci Type 1 was the most common configuration in maxillary premolars, followed by Vertucci Type 4. Single-rooted premolars were more prevalent, while two-root configurations were less common. C-shaped canal configurations were observed in a small percentage of premolars, with higher frequency in mandibular premolars. Cone beam computed tomography, Dental anatomy, Endodontics, Premolars, Root canal morphology.

Evaluation of Effective Bond Strength of Composite Resin to Etched Dentin after Dentin Pretreatment: An In-vitro Study

Aims: The aims of the study were to compare the deproteinizing effect of sodium hypochlorite, doxycycline, ethylenediaminetetraacetic acid (EDTA), and chitosan on effective shear bond strength of bonded composite resin to etched dentin. Materials and Methods: Forty extracted human maxillary premolars were taken, which were placed in a metal mold with acrylic resin. Teeth were divided into four groups according to the deproteinizing agents used, which are 5% NaOCl, 2% doxycycline, 17% EDTA, and 1% chitosan. Occlusal reduction of 1 mm below the dentin–enamel junction was done. Dentin deproteinizing agents were applied for 60 s and blot dried after acid etching. A universal dentin bonding agent was brushed and light cured. Cylindrical molds with composite resin were placed on the bonded surface and light cured. The shear bond strength was measured using a universal testing machine with a crosshead speed of 1.3 mm/min. Statistical Analysis Used: The Statistical Package for the Social Sciences (SPSS) for Windows, Version 22.0. released in 2013. Armonk, NY, USA: IBM Corp. was used to perform statistical analyses. One-way ANOVA test followed by Tukey’s Post hoc test was used to compare the mean shear bond strength between different groups. Results: Deproteinizing agent chitosan showed more bond strength compared to the other three agents used. Two percent doxycycline showed better shear bond strength followed by 5% NaOCl and 17% EDTA which had the least value for shear bond strength. Conclusions: Within the limitations of the present study, deproteinizing agents, when used after acid etching the dentin, can increase the bond strength. Chitosan showed to have a better deproteinizing effect compared to other agents used in the study.

Comparative Evaluation of Coronally Advanced Flap and Vestibular Incision Sub-Periosteal Tunnel Access Technique with Platelet-Rich Fibrin in the Treatment of Gingival Recession Defects- A Clinical Study

ABSTRACT Background and Aims: This study aim to treat gingival recession defects in the anterior and premolar teeth of the maxilla and mandible by comparing two methods the coronally advanced flap (CAF) and the vestibular incision subperiosteal tunnel access (VISTA), both of which involve using platelet-rich fibrin (PRF). Materials and Methods: An age range of 18 to 50 years was examined for the study, which included twenty-four participants. The patients were chosen at random from the Outpatient Department of Periodontology at Shree Bankey Bihari Dental College and Research Centre in Masuri-Ghaziabad, U.P. They were divided into two groups of twelve each, and they were all diagnosed with isolated gingival recession defects on human maxillary and mandibular anterior teeth and premolars. Both Group A and Group B had recession defects covered with PRF membranes; however, Group A had a CAF and Group B underwent VISTA. Clinical parameters measured at baseline, 1-month, 3-months, and 6-months postoperative intervals included recession length, recession width, probing depth, width of keratinized tissue, clinical attachment level, and percentage of root coverage. Result Both groups demonstrated notable enhancements in clinical parameters. However, the values of Group B were more statistically significant (P &lt; 0.05) by showing a reduction in probing depth, recession length, recession width, clinical attachment level, and gain in width of keratinized tissue, as well as a percentage of root coverage, as compared to Group A. Conclusion The VISTA technique was considered a more conservative approach for treating gingival recession defects with PRF membrane that showed good clinical outcomes and better results.

Fracture resistance of postendodontic restoration using self-adhesive bioactive resin and a bulk-fill composite with or without resin-impregnated glass fibers: An in vitro study.

Due to advancements in adhesive technology and the introduction of fiber reinforcement, there has been a paradigm shift towards a more minimally invasive approach in coronal restoration of endodontically treated teeth. This research aimed to evaluate and compare fracture resistance of postendodontic restoration using a self-adhesive bioactive resin and a bulk-fill composite with or without resin-impregnated glass fibers. Mesio-occlusal-distal cavities were prepared on 80 extracted human maxillary premolars. Root canal treatment was completed following standard access cavity preparation. Then, the teeth were divided into two groups based on the composite used for postendodontic restoration. Group I: Bulk-fill composite (Tetric N-Ceram). Group II: Activa BioActive. Group I and Group II were then divided into two subgroups depending on fiber incorporation (n = 20). Subgroup IA: Bulk-fill composite. Subgroup IB: Bulk-fill composite with fiber incorporation. Subgroup IIA: Activa BioActive. Subgroup IIB: Activa BioActive with fiber incorporation. The force required to fracture the teeth was recorded using the universal testing machine. Two-way ANOVA and Tukey's multiple post hoc test. Activa BioActive with fiber incorporation showed the highest mean fracture resistance (988.52N). Bulk-fill composite without fiber incorporation had the least mean fracture resistance (669.87N). Activa BioActive bulk-fill restorative material when used with the incorporation of resin-impregnated glass fibers can be a preferred material of choice for restoring endodontically treated teeth.

A comparative evaluation of human enamel remineralization ability of biomimetic nacre against casein phosphopeptide-amorphous calcium phosphate: An in vitro study.

This study aimed to assess and compare the efficacy of Nacre and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on the remineralization of enamel using surface microhardness analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. Twenty human maxillary premolars extracted for orthodontic reasons were collected. Under cool water spray, the crowns were sectioned mesiodistally into buccal and palatal halves using a diamond disc. The samples were subsequently mounted in self-cure acrylic resin. The samples were then subjected to Vickers hardness testing and SEM-EDX for baseline. To simulate carious lesions, all of the samples were acid-etched with 37% phosphoric acid for 30 s in a specific area on the enamel samples and subjected to surface microhardness testing and SEM-EDX. The enamel samples were randomly assigned to Group 1: Nacre water-soluble matrix (WSM), Group 2: Nacre varnish, and Group 3: CPP-ACP for remineralization. After 21 days, remineralization assessment of the test samples was done using SMH analysis and SEM-EDX analysis. Data obtained were statistically analyzed using the one-way analysis of variance to reveal the significant differences between the groups. Tukey's test was used for post hoc comparisons. All three groups showed a significant increase in surface microhardness. All three groups showed a significant calcium and phosphorous ratio increase after remineralization. Among the three groups, the highest Ca:P ratio was seen in the Nacre WSM group (0.58) followed by the Nacre Varnish (0.57) and CPP-ACP group (0.57). SEM images of the Nacre surface revealed the presence of extensive interlocking. A layer of packed hydroxyapatite particles was formed on the surface of the nacre through surface reactions. All the groups in the present study showed some extent of remineralizing ability irrespective of the different materials and mechanisms of action. Nacre WSM showed a remarkable hardness spike close to natural enamel after demineralization.

Evaluating the Effects of Cigarette Smoking and Heated Tobacco Products on Hard Dental Tissues: A Comparative Histological and Colorimetric Analysis.

This study aimed to evaluate and compare the impact of cigarette smoking (CS) and heated tobacco (HT) on the alteration of color and ultrastructural characteristics of human enamel and cementum. According to tobacco companies, a less harmful substitute for CS is HT products. Nevertheless, comprehensive research on the effects of HT on tooth structures has been lacking. This study aimed to evaluate and compare the impact of CS and HT on the alteration of color and ultrastructural characteristics of human enamel and cementum. Thirty intact and noncarious human maxillary premolars extracted for orthodontic treatment purposes, previously disinfected, were used in the study. The specimens were randomly separated into six groups (n = 10), as follows: Group 1: enamel without smoking exposure; Group 2: enamel exposed to CS; Group 3: enamel exposed to HT; Group 4: cementum without smoking exposure; Group 5: cementum exposed to CS; and Group 6: cementum exposed to HT. The measurement of color change was conducted using a spectrophotometer. The surface alterations and mineral composition of enamel and cementum were evaluated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. ANOVA test followed by Tukey's post hoc test was used to determine significant differences between groups. Results showed that CS had a more pronounced effect on enamel and cementum color changes than HT. The impact of CS and HT on color changes was more evident in cementum than in enamel. Surface morphology of enamel and cementum showed alterations in histology following exposure to both smoking types. Moreover, the mineral content experienced a significant reduction after using CS and HT. The reduction in calcium content after CS and HT exposure was similar. However, HT led to a significant decrease in the phosphorus content of enamel when compared with CS. At the same time, CS exposure in cementum resulted in a more significant reduction in Ca/P ratio than HT. Although HT may appear to present a lower danger to hard dental tissues than CS, it is not entirely harmless. CS results in more color changes on the enamel and cementum of teeth. Both smoking methods affected the mineral content of teeth, with CS having a significant effect on the roots, while HT significantly affected the crowns' mineral composition.

Efficacy of Different Irrigation Needles and Ultrasonic Activation on Calcium Hydroxide Removal: A Micro-CT Study Using 3D-Printed Endodontic Models

The aim of this study was to evaluate the efficacy of different irrigation needles and passive ultrasonic activation in removing Ca(OH)2 from an endodontic model that duplicated a root canal configuration of a human natural tooth. An extracted human maxillary premolar was subjected to root canal preparation and scanned with microcomputed tomography. A 3-dimensional reconstruction model of the natural tooth was printed to endodontic models using a polyjet printer. The root canals of the models were filled with Ca(OH)2 paste and divided into 2 groups based on the irrigation protocol: conventional syringe-needle irrigation (conventional group) and passive ultrasonic irrigation (PUI) group. Each group was subdivided into 3 groups (n=10) according to the type of needle: half-cut, side-vented, and TruNatomy irrigation needle. Microcomputed tomographyimaging was used to assess the percentage of reduction of Ca(OH)2. Data were analyzed using two-way analysis of variance test (α=.05). The side-vented and TruNatomy irrigation needles showed significantly higher percentage reductions than the half-cut needle (P<.05) in the conventional irrigation group. The PUI group showed significantly higher percentage reductions of Ca(OH)2 than the conventional group regardless of the type of needle (P<.05). However, no significant difference was found among the needles in the PUI group. The type of irrigation needle and the use of PUI influenced the removal efficacy of Ca(OH)2. PUI enhanced the removal of Ca(OH)2 regardless of the type of irrigation needle.

Comparative evaluation of shear bond strength of orthodontic brackets bonded with two self-etching adhesive systems: an in vitro study

Abstract Objective To evaluate and compare the shear bond strength (SBS of the new Optibond eXTRa Universal and Adper Prompt L-Pop self-etch adhesive systems using an in vitro experimental design. Patients and methods The sample included 40 freshly extracted human maxillary first premolars collected from orthodontic patients, adhering to ethical guidelines. The teeth were randomly assigned to two groups, one treated with Optibond eXTRa Universal self-etch adhesive and the other with Adper Prompt L-Pop. Stainless-steel brackets were then bonded to the teeth using BracePaste orthodontic adhesive composite resin. After storage and thermocycling, SBS was measured using a universal testing machine, and adhesive remnant index (ARI) scores were assessed under a digital microscope. Statistical analyses were performed, including the Shapiro–Wilk method, Student’s t-test for SBS, and χ 2 test for ARI scores. Results The mean SBS showed no significant difference between both groups (P = 0.076). However, the distribution of ARI scores exhibited a highly significant difference between the two groups (P &lt; 0.001). Conclusion While both adhesives exhibited similar bond strengths, variations in adhesive residue patterns highlight the importance of considering adhesive performance in orthodontic applications such as ease of cleanup and potential impact on enamel health.

A comparative evaluation of marginal fit and microleakage of computer-aided design/computer-aided manufacturing-milled zirconia and prefabricated posterior occlusal veneers: An in vitrostudy.

The aim of this study was to compare the marginal fit of prefabricated occlusal veneers with computer-aided design/computer-aided manufacturing (CAD-CAM)-milled zirconia occlusal veneers in the posterior teeth. Forty extracted human maxillary premolars were divided into two groups of 20 each. Group 1 was prepared to receive prefabricated occlusal veneers, and Group 2 was prepared to receive CAD-CAM-milled zirconia occlusal veneers. Prefabricated samples (Edelweiss) were selected for Group 1, whereas for Group 2, the tooth preparations were scanned, and occlusal veneers were fabricated using Exocad designing software and milling machine. After luting, both the groups were submerged in dye, sectioned, and evaluated for marginal fit and microleakage under a stereomicroscope using the microscope imaging software and its measurement tool. Data collected were subjected to statistical analysis using SPSS 27.0. Intragroup and intergroup comparison was done using the Mann-Whitney U test. The Chi-square test was applied to check the depth of penetration of dye based on percentages. The marginal gap of zirconia occlusal veneers fabricated with CAD-CAM is higher compared to that of prefabricated occlusal veneers. Similarly, the depth of penetration of dye is higher in CAD-CAM-milled zirconia occlusal veneers than prefabricated occlusal veneers. The marginal fit of prefabricated occlusal veneer is better than the marginal fit of zirconia occlusal veneers fabricated with CAD-CAM. Similarly, it can also be concluded that the microleakage of prefabricated occlusal veneer is less compared to the CAD-CAM-milled zirconia occlusal veneers.

Micro-shear bond strength of a novel resin-modified glass ionomer luting cement (eRMGIC) functionalized with organophosphorus monomer to different dental substrates

This study aims to assess and compare the micro-shear bond strength (μSBS) of a novel resin-modified glass-ionomer luting cement functionalized with a methacrylate co-monomer containing a phosphoric acid group, 30wt% 2-(methacryloxy) ethyl phosphate (2-MEP), with different substrates (dentin, enamel, zirconia, and base metal alloy). This assessment is conducted in comparison with conventional resin-modified glass ionomer cement and self-adhesive resin cement. In this in vitro study, ninety-six specimens were prepared and categorized into four groups: enamel (A), dentin (B), zirconia (C), and base metal alloys (D). Enamel (E) and dentin (D) specimens were obtained from 30 human maxillary first premolars extracted during orthodontic treatment. For zirconia and metal alloys, 48 disks were manufactured using IPS e.max ZirCAD through dry milling and Co-Cr powder alloy by selective laser milling. Each group was further subdivided into three subgroups (n=8) according to the luting cement used: (1) Fuji PLUS resin-modified glass ionomer luting cement (FP) as a control cement, (2) modified control cement (eRMGIC), and (3) RelyX U 200 (RU 200) self-adhesive resin cement. The two-way analysis of variance and Tukey's HSD were used to assess the data obtained from measuring the μSBS of the samples. The results of this study showed that the mean μSBS values of eRMGIC were statistically higher compared to FP in all tested groups (p<0.001). The mean μSBS results of eRMGIC were non-significantly different from those recorded by RU 200 for all substrates except for the dentin substrate, where the RU200 cement produced significantly higher strength (p<0.001). The failure modes were limited to a combination of mixed and adhesive failures without pure cohesive failure. The functionalization of FP with an organophosphorus co-monomer (2-MEP) directly affects the adhesion performance of the functionalized cement, which may be utilized to develop a new type of acid-base cement. It exhibited a performance comparable to that of resin-based cement and should serve well under different clinical conditions.

Comparative evaluation of three types of fiber orientation techniques on fracture resistance of endodontically treated premolars restored with composite resin: An in vitro study

ABSTRACT Introduction: A new technique of fiber reinforcement (horizontal + base fiber [HBF]) in the restoration of endodontically treated teeth (ETT) with composite resin was proposed. Aim: This study aims to compare three different types of fiber orientation techniques on fracture resistance of ETT. Materials and Methodology: Sixty intact extracted human maxillary premolars were assigned to five groups (n = 12). Group 1 intact teeth (control). The teeth in Groups 2–5 received endodontic treatment and a MOD cavity preparation and restored with composite resin with polyethylene fiber at different positions. Group 2: No fiber group (NF), Group 3: Occlusal fiber group (OF), Group 4: Horizontal fiber group (HF), and Group 5: HBF group. After thermocycling, the specimens were loaded using a universal testing machine until fracture and the fracture patterns were analyzed. Statistical Analysis: The data were analyzed statistically using analysis of variance with Tukey’s post hoc test (fracture load) and Chi-square test (fracture patterns). Results: Fiber-reinforced groups (OF, HF, HBF) showed significantly higher fracture resistance compared to NF group (P &lt; 0.05). No significant differences in fracture resistance were observed between (a) fiber-reinforced groups (OF, HF, HBF) and intact teeth (P &gt; 0.05) (b) amongst the fiber-reinforced groups (OF, HF, HBF) (P &gt; 0.05). With regard to fracture patterns, no significant differences were observed between the study groups (P &gt; 0.05). Conclusion: Restoring ETT with different techniques of fiber reinforcement resulted in the improvement of the fracture resistance comparable to that of intact teeth. The newly proposed technique of fiber insertion might be considered as an alternative to earlier techniques for the reinforcement of ETT.

Bonding Effectiveness of Saliva-Contaminated Monolithic Zirconia Ceramics Using Different Decontamination Protocols.

This research study investigated the effect of new decontamination protocols on the bonding capacity of saliva-contaminated monolithic zirconia (MZ) ceramics cemented with two different monomer-containing self-adhesive resin cements. Standardized tooth preparations (4 mm. axial height) were performed for eighty human maxillary premolars under constant water cooling system. Eighty monolithic zirconia crowns (Whitepeaks Supreme Monolith) (n = 8/10 groups) were manufactured by CAD-CAM. Specimens were kept in the artificial saliva at pH = 7.3 for 1 minute at 37°C except control groups. The specimens have not been prealumina blasted and grouped according to cleaning methods and resin cements: control groups (C) (no saliva contamination + GPDM + 4-META (N) (CN) and 10-MDP (M) containing resin cement (CM), alumina blasted (AL) + GPDM + 4-META (ALN) and 10-MDP containing resin cement (ALM), zirconium oxide containing universal cleaning agent (IC) applied + GPDM + 4-META (N) (ICN) and 10-MDP containing resin cement (ICM), pumice (P) applied + GPDM + 4-META (PN) and 10-MDP containing resin cement (PM), and air-water spray (AW) applied + GPDM + 4-META (AWN) and 10-MDP containing resin cement (AWM)). Monobond Plus was applied to all surfaces for 40 seconds before cementation. The thermal cycle was applied at 5,000 cycles after cementation. The crowns were tested in tensile mode at a speed of 1 mm/min. The mode of failure was recorded. SEM examinations were carried out at different magnifications. Data were analyzed using rank-based Kruskal-Wallis and Mann-Whitney tests. No significant differences were found between the surface treatments and between the two types of resin cements. Interaction effects between surface treatments and resin cements were found to be significant by two-way ANOVA analysis. ICM group resulted in significantly better bond strength results compared with CN. ICM was found to result in better bond strength results compared with PM. The combination of universal cleaning agent and 10-MDP containing resin cement had significantly the highest cementation bond strength values. The increasing order of mean tensile bond strength values of decontamination protocols was C < AW < P < AL < IC. The mean tensile bond strength of 10-MDP containing resin cement was slightly higher than GPDM + 4-META containing resin cement. Universal cleaning agents can be preferred as an efficient cleaning method with 10-MDP-containing cement after saliva contamination for better adhesive bond strength of 4 mm crown preparation height of monolithic zirconia ceramics.

Effect of artificial aging on the stability of color match of Omnichroma composite resin

Purpose To evaluate the effect of artificial aging on the stability of color match between the teeth and Omnichroma composite resin compared to that in the teeth restored with Tetric EvoCeram nanohybrid composite resin. Materials and methods Twenty sound, freshly extracted human maxillary premolars were mounted in acrylic blocks. The baseline shade of the selected teeth was A2 as measured from the middle third of the buccal surface by spectrophotometer (Vita Easyshade Advance). Trapezoidal Class V cavity was prepared on the buccal surface of each tooth 0.5 mm coronal to CEJ. Cavity dimensions were width of 4 mm occlusally and 3 mm gingivally, 2 mm occluso-gingival length and 1.5 mm depth. A 45-degree bevel was placed on the occlusal cavity margin. Results Specimens were randomly divided into two equal groups (n = 10) representing the materials used to restore the cavities. Group I: Tetric EvoCeram while Group II: Omnichroma. Specimens were artificially aged by storage for 6 months in artificial neutral saliva in an incubator at 37 ± 5°C during which the saliva was replaced daily. Color measurements and ΔE values were recorded before cavity preparation representing the baseline tooth color to be used for detection of the initial color match between the tooth and restoration where their color was measured after storage in saline for 24 h. Conclusion At the end of the storage period, the color of both the teeth and the restorations was remeasured to detect the stability of color match between the restoration and the tooth due to storage.

Comparing Zirconium Crown Marginal Adaptation in Preparations with Two Different Occlusal Reductions.

This study aimed to assess and contrast the effects on the vertical marginal fit of full contour CAD/CAM-generated monolithic zirconia crowns at pre- and post-cementation levels with various occlusal reduction schemes (planar and flat) and cements. Forty sound human maxillary first premolars were sampled for this study. The samples were divided into two main groups with twenty samples in each group according to the occlusal reduction scheme as follows: Group A included a chamfer finishing line design with a planar occlusal reduction scheme and Group B included a chamfer finishing line design with a flat occlusal reduction scheme. Each group was sampled into two subgroups (n = 10) based on the type of cement as follows: resin-modified glass ionomer cement (Fuji Plus) for subgroups A1 and B1, and a universal adhesive system (Duo Estecem II) for subgroups A2 and B2. Marginal gaps were tested in four indentations using a Dino light stereomicroscope (230×). Paired T-tests and Student's t-tests were used to analyze the data. Before cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, while subgroup B2 scored the highest mean; following cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, and subgroup B2 scored the highest mean of vertical marginal gap values. A chamfer finishing line design with a planar occlusal reduction scheme could be a preferable occlusal reduction scheme.

Optimizing fracture resistance of endodontically treated maxillary premolars restored with preheated thermos-viscous composite post-thermocycling, a comparative study. Part I

PurposeThis research aimed to investigate fracture resistance of endodontically treated maxillary premolars restored using preheated thermo-viscous and fiber-reinforced bulk fill resin composite, in vitro.MethodologySixty sound human maxillary premolars were selected and divided randomly into 6 groups of ten teeth each (n = 10). Group 1; is the positive control with sound unprepared teeth (P), Group 2; is the negative control in which Mesio-occluso-distal (MOD) cavities were left unrestored (N), Group 3; includes the teeth restored by incremental packing with conventional nanohybrid composite (ChP), Group 4; includes teeth restored with short fiber reinforced bulk fill composite (EF), Group 5; includes teeth restored with preheated thermo-viscous bulk fill composite (VB), and Group 6; includes teeth restored using packable bulk fill composite (XF) Tested restorative materials were bonded with a universal adhesive in self-etch mode. Teeth were kept in distilled water for 24 h at 37 °C proceeded by thermocycling (5- 55 °C, 1200×). Teeth were then exposed to compressive load till fracture at a crosshead speed of 1 mm/min. One-way ANOVA followed by Tukey post-hoc test was implemented to compare between more than two groups in non-related samples. The significance level was established at α = 0.05 for both tests.ResultsIntact teeth significantly recorded the highest fracture resistance values among all groups. A significant difference was recorded among all the tested groups, with the EF recording the highest values, followed by the VB group then the XF group and ChP that recorded the lowest data. Negative control premolars significantly recorded the lowest fracture.ConclusionsAfter thermocycling, endodontically treated maxillary premolars restored with pre-heated thermos-viscous composite did not exhibit an increase in fracture resistance. Notably, our findings indicate that short fiber-reinforced composite demonstrated significantly higher fracture resistance compared to other types of composites assessed in this study. This suggests the potential superiority of short fiber-reinforced composite in enhancing the overall structural integrity of endodontically treated teeth subjected to occlusal forces.