Effect of Surface Treatments on Adhesion of Milled Polyetheretherketone Post to Different Composite Resin Core Build-Up Materials.

Background: To evaluate the effect of surface treatments on adhesion of milled PEEK post to two different composite resin core-build up materials. Material and Methods: Six PEEK posts were divided into the following groups: G1: no treatment+ Grandio core material, G2: no treatment+ Bulk-fill core material, G3: 98% sulfuric acid for 60 seconds+ Grandio core material, G4: 98% sulfuric acid for 60 seconds+ Bulk-fill core material, G5: 50 µm airborne particle abraded + Grandio core material, G6: 50 µm airborne particle abraded + bulk fill core material. The adhesion of the post to core build-up materials was tested using micro push-out bond strength. Data were analyzed using ANOVA and Tukey's test. Results: There was a significant effect for the surface treatment (p<.001), a non-significant effect for the core build-up materials (p<.289), and a significant effect for their interaction (p<.001) on the bond strength values. Conclusions: Within the limitation of this study, sulfuric acid etching group significantly increased the bond strength compared to other groups. Bulk-fill core material could be a feasible option when restoring ETT in terms of saving chair time and the treatment procedure simplicity. Key words:Bond Strength, Core material, PEEK, Surface Treatment.

Influence of surface treatment on repair bond strength of CAD/CAM long-term provisional restorative materials: an in vitro study.

BACKGROUND: The surface treatment to improve the repair bond strength may vary because CAD/CAM provisional restoration polymers exhibit a variety of microstructures. This study was conducted to evaluate the effect of surface treatments on the repairability of three different CAD/CAM polymers for long-term provisional restorations. METHODS: Thirty specimens from each provisional restorative materials (CAD-Temp, Everest C-Temp, and PEEK) were divided into three groups: C: surfaces received no treatment; SB: surfaces were airborne particle abraded with 50 µm aluminum oxide; SB-T: surfaces received the same conditions as group SB in addition to thermocycling before and after treatment. Primer and nanohybrid repair resin composite were applied to the prepared CAD /CAM surfaces. The shear bond strength and the mode of failure were assessed. ANOVA and Tukey's significant difference tests were used to evaluate the data. RESULTS: The SB group had significantly higher repair SBS values (p < .001) compared to the other groups (C and SB-T). Everest C-Temp significantly recorded the highest repair SBS (17.84 ± 0.19 MPa) in group SB, while the lowest repair SBS values (5.51 ± 1.14 MPa) for CAD-Temp were recorded in group C. PEEK significantly recorded the second highest repair SBS (15.96 ± 0.18) in the SB group. CONCLUSIONS: Everest C-Temp had the highest repair SBS after an airborne abrasion particle. Thermocycling had no significant effect on the repair SBS for PEEK. Everest C-Temp and PEEK are recommended as long-term durable provisional materials for clinical use.

Bonding durability and remineralizing efficiency of orthodontic adhesive containing titanium tetrafluoride: an invitro study.

BACKGROUND: Titanium tetrafluoride has been shown to protect tooth enamel from demineralization. This study investigated the effect of incorporating different concentrations of TiF4 (1, 2 and 3 Wt.%) into an orthodontic primer on the shear bond strength of orthodontic brackets and the enamel microhardness after cariogenic challenges. METHODS: Three different TiF4 concentrations (1, 2 and 3 Wt.%) were prepared and added to the etch and rinse orthodontic primer. Ninety freshly extracted premolars were randomly divided into five groups according to the experimental primers and ageing conditions: TF0, TF0C, TF1C, TF2C, and TF3C. The TF0C group had no TiF4 in the primer, while TF1C, TF2C, and TF3C had 1, 2 and 3 Wt.% TiF4 in the primer, respectively. In the TF0 group, specimens were immersed in deionized water for 24 h as a control group, while all other groups were immersed in a demineralizing solution for 28 days. Each of the five groups was divided into two subgroups: The first group was subjected to shear bond strength and adhesive remnant index testing (N = 50 teeth, 10/group), while the second group was subjected to enamel surface microhardness testing (N = 25 teeth, 50 tooth halves, 10 tooth halves/group). Fifteen teeth (N = 15 teeth, n = 3/group) representing the five groups were subjected to SEM and microelemental analysis (EDX). SBS, ARI, microhardness, and Ca/P ratio were measured, and the data were analyzed using ANOVA and Tukey's tests. RESULTS: The TF2C group had the highest SBS value (9.93 ± 1.23), while the TF0C (5.24 ± 0.65) and TF3C (5.13 ± 0.55) had the lowest SBS values. The enamel microhardness in the TF0C group was significantly reduced (p < .001). Enamel microhardness values were significantly (p < .001) higher in groups TF1C, TF2C, and TF3C than in TF0C. The highest Ca/P ratio was significantly recorded for the TF2C group (2.65 ± 0.02). CONCLUSIONS: Incorporation of 1 and 2 Wt.% TiF4 into the orthodontic primers showed adequate bond strength and better remineralization effect. However, 1 Wt.% TiF4 showed lower ARI values than 2 Wt.% TiF4.

Resilient Stud Versus Bar Attachments for Inclined Implants Supporting Mandibular Overdentures. An In Vitro Study of Loading and Dislodging Strains.

PURPOSE: To evaluate strain around resilient stud and bar attachments for inclined implants supporting mandibular overdentures during loading and dislodging. MATERIALS AND METHODS: A mandibular edentulous model was printed using the laser sintering technique. Two vertical implants and two 30-degree distally inclined implants were placed in canine and premolar areas, respectively. Overdentures were attached to the implants with either a resilient stud (Locator, group 1) or a bar/clip (group 2) attachment. Three strain gauges were mounted at the buccal, lingual, and proximal surfaces of each implant. Microstrains were registered during vertical loading and dislodging force applications and compared between attachments (resilient stud and bar) and implant positions (vertical and inclined). RESULTS: For canine implants, bar overdentures recorded significantly higher microstrains than Locator overdentures during vertical loading. For premolar (inclined) implants, Locator overdentures recorded significantly higher microstrains than bar overdentures during vertical dislodging. For both groups (during loading) and the bar overdenture group (during dislodging), canine (vertical) implants showed significantly higher microstrains than premolar (inclined) implants. CONCLUSION: Within the limitations of this in vitro study, canine (vertical) implants may be at risk of increased stresses during loading if bar attachments are used for vertical and inclined implants supporting mandibular overdentures, and premolar (inclined) implants may be at risk of increased stresses during dislodging if Locator attachments are used. For both attachments, canine implants showed significantly higher microstrains than premolar implants during loading and dislodging.

Effect of surface treatments and flash-free adhesive on the shear bond strength of ceramic orthodontic brackets to CAD/CAM provisional materials.

OBJECTIVES: To evaluate the effect of surface treatments and flash-free adhesive on the shear bond strength of ceramic orthodontic brackets bonded to materials used for the fabrication of CAD/CAM provisional crowns. MATERIALS AND METHODS: Specimens (n = 160) from each provisional material (CAD-Temp and C-Temp) were categorized into four groups according to the surface treatment methods: C (no surface treatment), HP (37% H3PO4), DB (mechanical roughening by diamond bur), and SB (mechanical roughening by blasting). Maxillary central incisor ceramic brackets (Clarity™ Advanced ceramic brackets, 3 M Unitek) were bonded to the conditioned provisional materials according to the used adhesive system (n = 20), APC PLUS or APC flash-free. All specimens were evaluated for shear bond strength testing (SBS) and the adhesive remnant index (ARI). Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. RESULTS: C-Temp significantly recorded higher SBS than CAD-Temp (24.0 and 16.0 MPa, respectively) (p < 0.001). DB and SB groups utilizing flash-free adhesive significantly recorded higher SBS (18.2 and 24.0 MPa, respectively) (P < 0.05) compared to other groups in the tested materials. Higher ARI scores were recorded in CAD-Temp and flash-free adhesive. CONCLUSIONS: Mechanical surface treatments and flash-free adhesive would enhance SBS of ceramic orthodontic brackets to CAD/CAM provisional materials. The higher ARI scores reported with CAD-Temp and flash-free adhesive reduce chair time for excess removal. CLINICAL RELEVANCE: Bonding of orthodontic brackets to provisional restorations is a challenge for orthodontists in adult comprehensive cases that could be improved by an appropriate provisional material, surface treatments, and adhesive system.

Bond strength and elemental analysis of oxidized dentin bonded to resin modified glass ionomer based restorative material.

BACKGROUND: This study aimed to investigate the influence of hesperidin application on the bonding of resin-modified glass ionomer-based restorative material to dentin treated with oxygen-induced endodontic irrigants. MATERIAL AND METHODS: One hundred human permanent molars were categorized into five groups (n= 20/group), treated with various irrigants as follows: Group C; distilled water (control group), Group SH; 5.25% NaOCl, Group SH+H; 5.25% NaOCl + 5 % hesperidin, Group HP; 10% H2O2, Group HP+H; 10% H2O2 + 5 % hesperidin. Specimens were bonded with RMGI based restorative material. For each group, half of the specimens were evaluated for µSBS by a universal testing machine and the other half for dentin ion uptake by EDX. Additional ten specimens (n=2/per group) were prepared for the micro-morphological analysis under SEM. RESULTS: Hesperidin groups improved the µSBS, with a significant effect for HP+H group (p<. 05). Dentin ion uptake was significantly (p<. 05) improved in hesperidin groups. CONCLUSIONS: In conclusion, Application of hesperidin in conjunction with RMGI based restorative material improved the dentin bond strength and ion uptake; this could be a promising approach to aid dental practitioners in their decisions, regarding which restorative material to use especially in caries susceptible patients. Key words:Hesperidin, elemental analysis, bond strength.

Retention and Stability of Rigid Telescopic and Milled Bar Attachments for Implant-Supported Maxillary Overdentures: An In Vitro Study.

PURPOSE: This study aimed to evaluate and compare the retention and stability of rigid telescopic and milled bar attachments for implant-supported maxillary overdentures. MATERIALS AND METHODS: An acrylic resin model of the edentulous maxilla without alveolar undercuts was fabricated, and four implants were inserted in the canine and second premolar areas of the model. Two experimental overdentures were constructed and connected to the model with either rigid telescopic (RTA) or milled bar (MBA) attachments. Resistance of overdentures to axial and nonaxial (anterior, posterior, and lateral) dislodging forces was measured to represent retention and stability, respectively. Measurements were made at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (retention after wear simulation). RESULTS: After wear simulation, MBAs recorded significantly higher retention (P < .001) and stability against anterior dislodging (P < .001) than RTAs. RTAs recorded significantly higher stability against posterior (P = .022) and lateral (P < .001) dislodging than MBAs. Initial stability of RTA against anterior (P < .001) and posterior (P < .001) dislodging was significantly higher than stability after wear simulation. Retention of RTAs (P = .020) and stability of MBAs against posterior (P = .038) and lateral (P = .020) dislodging after wear simulation were significantly higher than initial values. CONCLUSION: MBA was associated with increased retention of maxillary implant overdentures compared with RTA, while RTA was associated with increased stability compared with MBA.