During storage of frozen par-baked breads for a prolonged period of time, bread quality may undergo changes such as increased firmness, moisture and flavour losses resulting in product deterioration. ...Four categories of par-baked breads namely—variety, white, multi-grain and rye were stored at −18°C for 9 months to evaluate the effects of storage period on product quality, and to develop prediction models that describe kinetics of deterioration of selected quality parameters. The quality was evaluated based on sensory, chemical and physical attributes and properties. Storage life was determined based on the changes in bread quality below certain level. The principal component analysis indicated that approximately 90% of the total variability of 19 quality parameters can be explained with only two principal components. The zero-order kinetic reaction showed good agreement (
R
2>80%) with quality changes observed by the sensory panel over the storage period. A prediction model, based on the bread quality at zero time and the quality at the time when the bread was rejected by the sensory panel, was developed. The proposed prediction model would provide a useful means of estimating storage life of par-baked breads made with similar formulations.
Abstract Introduction Preserving intact coronal and radicular tooth structure, especially maintaining cervical tissue to create a ferrule effect, is considered to be crucial for the optimal ...biomechanical behavior of restored teeth. The ferrule effect has been extensively studied and still remains controversial from many perspectives. The purpose of this study was to summarize the results of research conducted on different issues related to the ferrule effect and published in peer-reviewed journals listed in PubMed. Methods The search was conducted using the following key words: “ferrule” and “ferrule effect” alone or in combination with “literature review,” “fracture resistance,” “fatigue,” “finite element analysis,” and “clinical trials.” Results The findings from reviewed articles were categorized into three main categories: laboratory studies, computer simulation, and clinical trials. Laboratory studies were further classified into subchapters based on the main aspect investigated in relation to the ferrule effect. Conclusions The presence of a 1.5- to 2-mm ferrule has a positive effect on fracture resistance of endodontically treated teeth. If the clinical situation does not permit a circumferential ferrule, an incomplete ferrule is considered a better option than a complete lack of ferrule. Including a ferrule in preparation design could lead to more favorable fracture patters. Providing an adequate ferrule lowers the impact of the post and core system, luting agents, and the final restoration on tooth performance. In teeth with no coronal structure, in order to provide a ferrule, orthodontic extrusion should be considered rather than surgical crown lengthening. If neither of the alternative methods for providing a ferrule can be performed, available evidence suggests that a poor clinical outcome is very likely.
Self-adhesive resin cements: a literature review Radovic, Ivana; Monticelli, Francesca; Goracci, Cecilia ...
The journal of adhesive dentistry,
08/2008, Letnik:
10, Številka:
4
Journal Article
Recenzirano
To summarize research conducted on self-adhesive cements and provide information on their properties, based on the results of original scientific full-length papers from peer-reviewed journals listed ...in PubMed.
The search was conducted using the term "self-adhesive cement OR (trade names of currently available products)".
Only in vitro studies that investigated two commercially available self-adhesive cements have been published so far. The results were summarized into the following categories: adhesion to tooth substrates (enamel, dentin, root dentin), adhesion to restorative materials (endodontic posts, ceramics, titanium abutments), marginal adaptation, microleakage, mechanical properties, biocompatibility, chemical adhesion and fluoride release, and ratings in clinical use.
The majority of available literature data is based on studies that investigated one of the self-adhesive cements that are currently available to clinicians. According to the in vitro results, self-adhesive cement adhesion to dentin and various restorative materials is satisfactory and comparable to other multistep resin cements, while adhesion to enamel appears to be a weak link in their bonding properties. Long-term clinical performance of these materials needs to be assessed prior to making a general recommendation for their use.
Abstract Objectives The aim of this study was to investigate the effect of fiber post light transmitting ability to the continuity of resin cement-root dentin (C-RD) and resin cement-fiber post ...(C-FP) interface, elastic modulus and hardness of a dual-cure resin cement. Methods Spectrophotometric measurements were applied for the determination of light transmission at coronal, middle and apical level as well as at the apical tip through Tech 21 X-OP (TECH) and DT Light Post (DT). Posts were cemented using dual-cured resin cement (Calibra). Roots were sectioned longitudinally through the post. Epoxy resin replicas were made and used to evaluate C-RD and C-FP interface under SEM. Modulus of elasticity ( E ) and Vicker's hardness (VH) of the cement layer were assessed. Results No light transmission was detected through TECH. Light transmission through DT decreased from coronal to apical and rose at the apical tip. TECH presented a significantly lower percentage of continuous C-RD and C-FP interface in comparison to DT. Coronal third of C-RD interface in TECH specimens had a significantly higher percentage of continuity than apical third. No regional differences in continuity of C-RD interface were found in DT specimens. E and VH were significantly lower when TECH was used, and decreased from coronal to apical for both posts. Significance Cementation of fiber post with no light transmitting ability using a dual-cured resin cement resulted in lower E and VH of the cement layer, and lower percentage of continuous C-RD and C-FP interface in comparison to cementation of light transmitting fiber post.
The aim was to assess the influence of cement translucency on the retentive strength of luted fiber posts. Twenty extracted human premolars were randomly divided into four equal groups, based on the ...combinations of materials to be tested. Two post types of the same size, shape, and chemical composition, but different light‐transmission properties Translucent post (TP) and Opaque post (OP) were selected. The two post types were luted using the etch‐and‐rinse, light‐curing adhesive in combination with two shades of the same resin cement of markedly different light‐transmitting ability Transparent shade (TS) and Opaque shade (OS). Early post retention was assessed using the thin‐slice push‐out test. Post type did not significantly influence post retention; however, cement translucency emerged as a relevant factor in intraradicular cementation, with the TS achieving higher push‐out strengths. The between‐factor interaction was also statistically significant; specifically, OP‐OS yielded significantly lower retentive strengths than all the other groups. Post translucency did not influence post retention, provided that a highly translucent cement was utilized for luting.
To assess the influence of preliminary phosphoric acid-etching on shear bond strength (SBS) to enamel and dentin of a self-adhering restorative composite and of a new self-etch adhesive used in ...combination with the proprietary flowable composite.
100 human molars were selected. SBS was assessed on flat buccal enamel surfaces and mid-coronal dentin. Teeth from each group were divided into five subgroups (n=10): (1) FL: etch-and-rinse adhesive OptiBond FL/Premise flowable; (2) XTR: 2-step self-etch adhesive OptiBond XTR/Premise flowable; (3) eXTR: OptiBond XTR on etched substrates/Premise flowable; (4) VF: self-adhering flowable composite Vertise Flow; (5) eVF: Vertise Flow on etched substrates. Specimens were stressed in shear until failure. Failure modes were evaluated under a stereomicroscope. Data were analyzed by two-way ANOVA and Fisher's exact test (P< 0.05).
Dental substrate, material and between-factor interaction significantly influenced SBS (MPa). In FL group (16.83 +/- 2.93) significantly higher SBS to enamel than in the other groups (XTR 8.59 +/- 4.39; eXTR 7.04 +/- 3.63; VF 6.61 +/- 2,41; eVF 9.87 +/- 4.24) was measured. On dentin FL (8.15 +/- 3.88) performed similarly to XTR (10.60 +/- 5.0), eXTR (9.60 +/- 4.91) and eVF (5.48 +/- 4.94); VF recorded significantly lower SBS (2.94 +/- 2.79 MPa). Failure modes differed significantly among groups.
Abstract Objectives To evaluate the influence of different surface treatments on the microtensile bond strength of a dual-cured resin composite to fiber posts. Methods Thirty-two glass ...methacrylate-based fiber posts (GC Corp.) were used in the study. Posts were divided into two groups, according to the surface pretreatment performed. Group 1: sandblasting (Rocatec-Pre, 3 M ESPE). Group 2: no pretreatment. In each of the two groups posts received three types of additional “chair-side” treatments. (1) Silane application (Monobond S, Ivoclar Vivadent); (2) adhesive application (Unifil Core self-etching bond, GC); (3) no treatment was performed. A dual-cured resin composite (Unifil Core, GC) was applied on the posts to produce cylindrical specimens. Specimens were cut to obtain microtensile sticks that were loaded in tension at a cross-head speed of 0.5 mm/min until failure. The morphology of the post/composite interface and the post surface morphology were evaluated under SEM. Statistical analysis was performed with two-way ANOVA and Tukey test for post hoc comparisons ( p < 0.05). Results Post surface pretreatment did not prove to be a significant factor in post-composite bond strength ( p = 0.08), whereas “chair-side” treatment modalities and the interaction between pretreatment and treatment showed a significant influence on bond strength ( p < 0.001). When no “chair-side” treatment was performed, bond strength was significantly higher on sandblasted posts. Additional adhesive application resulted in significantly lower bond strength on sandblasted posts. When no pretreatment was performed, silane application resulted in higher bond strength than adhesive application. Conclusions Sandblasting may give an increase in microtensile strength to methacrylate-based glass fiber posts, eliminating the need for additional “chair-side” treatments. Reducing the number of clinical steps could contribute to simplify the clinical procedures.
To investigate the applicability of flowable composites as post luting agents by assessing the push-out strength of posts.
36 intact single rooted human premolars were selected. The endodontic ...treatment was performed and half of the specimens were restored with light transmitting posts (DT Light Post Illusion) and the other half with opaque posts (Tech 21 X-OP). In both groups the following combinations of adhesive/cement were tested: OptiBond Solo Plus/Nexus Third Generation (NX3), XP Bond/SureFil SDR Flow (SDR), and Vertise Flow (VF). Push-out test was used to assess the retentive strength of fiber posts, which was expressed in megapascals (MPa). Specimens were analyzed under a stereomicroscope to determine failure mode (adhesive between luting agent and post, adhesive between luting agent and dentin or mixed failure). Push-out data and failure mode distribution were analyzed by two-way ANOVA and Chi-square test, respectively (P< 0.05).
The statistical analysis revealed that only the type of luting material significantly influenced push-out bond strength of the post (P< 0.001). SDR (9.00 +/- 2.17 MPa) performed similarly to the control group NX3 (7.15 +/- 1.74 MPa), while VF (4.81 +/- 1.51 MPa) should significantly lower bond strength. Failure modes differed significantly among groups.
To assess the shear bond strength to unground human enamel (ESBS) and flexural strength (FS) of different reinforcing fibers used in combination with a flowable composite resin.
For ESBS testing, 90 ...human molars were selected and randomly divided into 9 groups (n = 10) according to the reinforcing fiber to be tested: 1. RTD Quartz Splint additionally impregnated at chairside with Quartz Splint Resin (RTD); 2. RTD Quartz Splint without additional impregnation; 3. Ribbond-THM (Ribbond) impregnated with OptiBond FL Adhesive; 4: Ribbond Triaxial (Ribbond) impregnated with OptiBond FL Adhesive; 5. Connect (Kerr) impregnated with OptiBond FL Adhesive; 6. Construct (Kerr) impregnated with Opti- Bond FL Adhesive; 7. everStick PERIO (Stick Tech); 8. everStick C&B (Stick Tech); 9. nonreinforced composite Premise flowable (Kerr). Cylinders of flowable composite reinforced with the fibers were bonded to the intact buccal surface of the teeth. After 24 h of storage, shear loading was performed until failure occurred. FS was assessed performing three-point bending test according to ISO Standard 4049/2000. ESBS and FS data were analyzed using one-way ANOVA, followed by Tukey's HSD test for post-hoc comparisons (p < 0.05).
For each group, the ESBS and FS, respectively, in MPa were: 1. 17.07 ± 4.52 and 472.69 ± 30.49; 2. 14.98 ± 3.92 and 441.77 ± 61.43; 3. 18.59 ± 5.67 and 186.89 ± 43.89; 4. 16.74 ± 6.27 and 314.41 ± 148.52; 5. 14.38 ± 4.14 and 223.80 ± 77.35; 6. 16.00 ± 5.55 and 287.62 ± 85.91; 7. 16.42 ± 3.67 and 285.35 ± 39.68; 8. 23.24 ± 5.81 and 370.46 ± 29.26; 9. 12.58 ± 4.76 and 87.75 ± 22.87. For most fibers, no significant difference in ESBS was found compared to the control group, except for everStick C&B, which yielded higher ESBS. Nonreinforced composite exhibited the lowest FS, while all fibers positively affected the FS.
Fiber reinforcement of flowable composite does not affect its ESBS. The flexural strength of FRCs is significantly influenced by fiber composition and pattern.
to determine the bond strength to unground enamel of all-in-one adhesives in comparison with an etch-andrinse system and to compare the reliability of microtensile and microshear methods in providing ...such measurements.
the bonding procedure was performed on enamel of 64 extracted molars. The tested all-inone adhesives were: Bond Force (Tokuyama), AdheSE One (Ivoclar-Vivadent), and Xeno V (Dentsply). Prime&Bond NT (Dentsply) served as control. Microtensile specimens were obtained from 4 teeth per group. Twelve teeth per group were used for microshear testing. Microtensile specimens that failed prior to testing were included in statistical calculations; they were assigned the lowest value measured in the respective group. Failure modes were observed under light microscope and classified (cohesive within substrates, adhesive, mixed). Statistically significant differences in bond strength were assessed among the adhesives within each testing method and between microshear and microtensile data for each adhesive. Failure mode distributions were compared using the chi-square test.
all-in-one adhesives had similar microshear and microtensile bond strengths. In both testing methods, the etch-and-rinse system achieved the strongest bond. For all adhesives, significantly higher bond strengths were measured with the microshear test. In microtensile testing, specimens bonded with the etch-and-rinse adhesive exhibited a significantly different distribution of failure modes. The coefficients of variation were extremely high for microtensile bond strength data, particularly of all-in-one adhesives.
the adhesive potential to intact enamel of recently introduced all-in-one adhesives was inferior to that of an etch-and-rinse system. When testing bond strength to enamel of all-in-one adhesives, microshear testing may be a more accurate method than microtensile.
