Biomedical subjects

Francesca Monticelli

Publications and source records attributed to Francesca Monticelli.

28 records · Page 2Linked to original sources

PubMed2005

In vitro evaluation of wall-to-wall adaptation of a self-adhesive resin cement used for luting gold and ceramic inlays.

PURPOSE: This in vitro study evaluated the wall-to-wall adaptation of a new self-adhesive resin-based cement (RelyX Unicem) in comparison with that of other cements when luting gold and porcelain inlays in standardized Class II cavities in extracted teeth. MATERIALS AND METHODS: In each experimental group (n = 10), a different combination of inlay and luting material was tested. Group 1: Porcelain Empress II (Ell) and RelyX Unicem (U); group 2: Ell and resin-based cement Variolink II in combination with primer and bonding Excite DSC; group 3: gold inlays (G) and U; group 4: G and Harvard zinc-oxy-phosphate cement; group 4: G and glass-ionomer cement Fuji Cem. After storage and thermocycling, microleakage testing was carried out and dye penetration was examined at the occlusal and cervical margins of each inlay. The differences in microleakage score were tested for statistical significance first comparing all groups, then pooling the groups for inlay material (Kruskal-Wallis nonparametric ANOVA and Mann-Whitney U test, p < 0.05). SEM observations of the tooth/cement/restoration interfaces were also made in each group. RESULTS: Harvard cement had the highest microleakage. The sealing ability exhibited by RelyX Unicem was satisfactory with both gold and porcelain inlays, and comparable to that of Fuji Cem and Variolink II. CONCLUSION: RelyX Unicem achieved an adequate seal on both enamel and dentin when used to lute in vitro gold and porcelain inlays.

Dental Cavity Preparation↗

PubMed2005

SEM evaluation of the cement layer thickness after luting two different posts.

PURPOSE: To verify with SEM the cement layer thickness and uniformity of resin-relined translucent fiber posts (anatomic posts) and standard translucent fiber posts. MATERIALS AND METHODS: On 20 extracted maxillary anterior teeth, the roots were endodontically treated and prepared for the insertion of a fiber post. Translucent fiber posts (DT) were luted with a dual-curing resin cement (Duo-Link) in 10 specimens (group 1) after the canal walls had been treated with the One-Step bonding system. In the other 10 specimens (group 2), experimental anatomic posts (Anatomic Post'n Core) were tested. To these posts, a layer of light-curing resin is added to allow for a pre-cementation relining of the post, aimed at improving its fit into the endodontic space. For luting, the same adhesive-resin cement combination of group 1 was used. All the roots were sectioned and prepared for SEM observations. At the 1-mm, 4.5-mm, and 8-mm level of each root, cement thickness was measured, and the presence of gaps or voids within the luting material or at its interfaces was evaluated. A statistical analysis was performed to test the significance of differences in the cement layer thickness around the two types of post and at different levels of the same type of post. RESULTS: In the presence of anatomic posts, the cement layer was significantly thinner and more uniform at the coronal and middle level of the root. In both groups, voids and bubbles were detected within the luting material, within the abutment material, and between fiber post and cement. Gaps were also visible between post and relining material. CONCLUSIONS: The resin cement thickness was significantly lower in the anatomic post group than in the control group (standardized posts), except at the apical third of the canal, where there was no statistically significant difference. A good adaptation of anatomic posts was evident in all of the specimens.

Analysis of Variance↗

PubMed2004

Microtensile bond strength to ground enamel by glass-ionomers, resin-modified glass-ionomers, and resin composites used as pit and fissure sealants.

OBJECTIVES: To measure the microtensile bond strength to ground enamel of different types of materials used as pit and fissure sealants in combination with different substrate conditioners. METHODS: From 40 sound extracted molars, eight groups of five teeth were randomly formed. The experimental groups were: (1) (C) 37% phosphoric acid/ClinPro Sealant (3M ESPE); (2) (G) 37% phosphoric acid/Guardian Seal (Kerr); (3) (E/TF) 37% phosphoric acid/Excite/Tetric Flow (Ivoclar-Vivadent) (4) (OS/UF) 37% phosphoric acid/One Step (Bisco)/UniFil Flow (GC); (5) (OS/AE) 37% phosphoric acid/One Step/AEliteflo (Bisco); (6) (UB/UF) UniFil Bond/UniFil Flow (GC); (7) (CC/FVII) GC Cavity Conditioner/Fuji VII (GC); (8) (CC/FII) GC Cavity Conditioner/Fuji II LC Improved (GC). On the buccal of each tooth, a 5mm high build-up was created by incrementally adding layers of the sealing material on the conditioned enamel. By serially cutting the built-up tooth, multiple beam-shaped specimens about 1mm x 1mm in cross section were obtained, and loaded in tensile (0.5 mm/min) until failure occurred. RESULTS: The bond strengths measured in MPa were: (C) 20.41+/-11.79; (G) 16.02+/-7.99; (E/TF) 24.06+/-9.67; OS/UF 15.63+/-9.00; (OS/AE) 9.31+/-6.05; (UB/UF) 4.96+/-3.46; (CC/FVII) 1.70+/-2.19; (CC/FII) 2.19+/-1.44. CONCLUSIONS: The conventional and the resin-modified glass ionomers measured bond strengths significantly lower than those of any resin-based materials. Failure frequently occurred cohesively within the cement. Flowable composites in combination with phosphoric acid and a total-etch adhesive performed similarly to resin-based materials specifically conceived for sealings, such as ClinPro Sealant and Guardian Seal. The bond achieved by resin composite when treating enamel with the self-etching primer used in this study (UniFil Bond) was significantly lower than that developed when the substrate was etched with 37% phosphoric acid.

Acrylic Resins↗

PubMed2004

Influence of substrate, shape, and thickness on microtensile specimens' structural integrity and their measured bond strengths.

OBJECTIVES: To verify whether substrate, shape, or thickness of microtensile specimens have a significant influence on their measured bond strength. METHODS: Sixty-four extracted molars provided microtensile specimens, which were prepared on enamel and dentin, in different shapes and thicknesses. The teeth were randomly divided into 16 groups (n = 4). Groups 1-8 included hourglass-shaped specimens. In Groups 1-4 specimens were prepared from enamel and in a thickness at the bonding interface of 0.5 mm x 0.5 mm, 1 mm x 1 mm, 1.5 mm x 1.5 mm, and 2 mm x 2 mm, respectively. In these same thicknesses, hourglasses were trimmed in Groups 5-8, but the specimens were prepared from dentin. Groups 9-16 included specimens obtained following the non-trimming technique. Groups 9-12 provided enamel sticks in the four evaluated thicknesses. In these same thicknesses and shape but from dentin were cut the specimens of Groups 13-16. Two specimens from each group were viewed using a scanning electron microscope. On the other ones, microtensile bond strength was measured and the values were statistically analyzed. RESULTS: Substrate, shape, and thickness of the specimens had a significant effect on their recorded bond strength (p < 0.05). Higher bond strength values were recorded by dentin versus enamel specimens and by sticks versus hourglasses. Also, bond strength decreased as specimen thickness increased. SEM analysis revealed that the trimmed specimens, especially if from enamel, often exhibited lines of fracture in the area of action of the bur. SIGNIFICANCE: It seems advisable to avoid the trimming action particularly on enamel specimens. If the hourglass shape is preferred, the cross-sectional area should not exceed 1 mm x 1 mm.

Analysis of Variance↗

PubMed2004

Micromorphology of the fiber post-resin core unit: a scanning electron microscopy evaluation.

OBJECTIVES: [corrected] To microscopically evaluate the structural characteristics of post-and-core units made with a fiber post and different types of composite resins used as build-up materials. MATERIALS AND METHODS: Forty endodontically treated human maxillary incisors were prepared for receiving a fiber post (Aesthetic Post Plus, RTD). One-Step (Bisco) was used as a bonding material, and C&B resin cement (Bisco) for luting the post. The posted roots were randomly divided into eight groups. In each group a different material or technique was applied to build up the abutment. The materials on trial were Z100 (3M-ESPE), Lumiglass (RTD), Gradia (GC), Build-it! (Jeneric Pentron). On the specimens of Groups 5-8, the same materials were used for build-ups, with the addition of a preshaped plastic shell (Composipost, Core Form, RTD). All the post-and-core specimens were cut perpendicular to their long axis and processed for SEM observation. The objective was to detect the presence of voids/bubbles within the resin abutment, and of gaps at the interface between the post surface and the core material. These aspects were quantified with reference to indexes. The differences among the scores were tested for statistical significance (p<0.05). RESULTS: In the absence of any matrix, cores built up with Gradia showed the highest integrity, and those made with Z100 the best adaptation onto the post. In the presence of shells, Build-it! provided the most satisfactory result. Build-it! was the only material to perform better when used in combination with a shell. SIGNIFICANCE: When hybrid composites are used to build up a core onto a fiber post, a higher homogeneity of the abutment and a better post-core integration are achieved if the build up is done in the absence of any matrix.

Composite Resins↗

PubMed2004

The adhesion between fiber posts and root canal walls: comparison between microtensile and push-out bond strength measurements.

Aim of the study was to compare the trimming and non-trimming variants of the microtensile technique with the 'micro' push-out test in the ability to measure accurately the bond strength of fiber posts luted inside root canals. In 15 endodontically treated teeth (Group A), fiber posts were cemented with Excite DSC in combination with Variolink II (Ivoclar-Vivadent). In 15 roots RelyX Unicem (3M-ESPE) was used for fiber post luting (Group B). Within each group, the bond strength of cemented fiber posts was assessed with the trimming and non-trimming microtensile technique, as well as with the push-out test. The great number of premature failures (16.9% in Group A, 27.5% in Group B) and the finding of high standard deviation values make questionable the reliability of the trimming microtensile technique. With the non-trimming microtensile technique, only five sticks were obtained from a total of six roots. The remaining specimens failed prematurely during the cutting phase. With the push-out test no premature failure occurred, the variability of the data distribution was acceptable, and regional differences in bond strength among root levels could be assessed. Relatively low values of bond strength were, in general, recorded for luted fiber posts. In conclusion, when measuring the bond strength of luted fiber posts, the push-out test appears to be more dependable than the microtensile technique.

Dental Bonding↗

PubMed2004

Microtensile bond strength of self-etching adhesives to enamel and dentin.

PURPOSE: To measure the microtensile bond strength to enamel and dentin of three self-etching adhesives in comparison with a total-etch two-step system as a control. MATERIALS AND METHODS: A total of 40 extracted human molars were stored in saline solution until use, then divided into 4 groups of 10 teeth (one group per adhesive system). Half of each of these groups underwent bond strength tests on enamel, and the other half was used for adhesion testing on dentin. The following experimental groups (n = 5) were then formed: E(1) Adper Prompt-L-Pop (AP, 3M ESPE) on enamel; E(2) Xeno CF II (X, Sanking Kogyo) on enamel; E(3) AdheSE (AS, Ivoclar-Vivadent) on enamel; E(4) Excite (EX, Ivoclar-Vivadent) on enamel; D(1) AP on dentin; D(2): X on dentin; D(3) AS on dentin; D(4) EX on dentin. Each tooth yielded 15 to 20 sticks about 0.9 x 0.9 mm in cross-sectional area for microtensile testing. Specimens were loaded in tension at a crosshead speed of 0.5 mm/minute, and bond strength at failure was calculated in MPa. A two-way ANOVA was applied to test for significance of the differences among the groups. RESULTS: The bond strength values of Excite (the control) were significantly higher than those of the test products on enamel (42.92+/-4.8 MPa) and on dentin (45.80+/-5.79 MPa). The self-etching adhesives AdheSE (28.48+/-4.71 MPa) and Xeno CF II (27.22+/-2.74 MPa) revealed significantly stronger adhesion than Adper Prompt-L-Pop (20.16+/-2.07 MPa) on dentin. On enamel, all self-etching test materials performed similarly. The substrate did not appear to have a significant influence on adhesion, as each material reached comparable levels of bond strength on enamel and dentin. CONCLUSION: On both substrates the self-etching adhesives tested performed significantly worse than did the total-etch system.

Acrylic Resins↗

PubMed2002

Influence of a microbrush on bonding fiber post into root canals under clinical conditions.

OBJECTIVE: The objective of this clinical report was to evaluate the effectiveness of a microbrush as a carrier of priming-adhesive solution in formation of resin tags, adhesive lateral branches, and resin-dentin interdiffusion zone (RDIZ) when the brush was used to bond fiber posts under clinical conditions. STUDY DESIGN: Twenty endodontically treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed, and their written consent was obtained. The samples were randomly divided into 2 groups of 10 samples each. In group 1, One-Step (Bisco, Schaumburg, Ill) was applied with a brush with Duo-Link resin cement (Bisco). In group 2, One-Step was applied with a microbrush with Duo-Link resin cement (Bisco). Use of the adhesive systems and resin cements was strictly according to manufacturers' instructions. The priming-adhesive solution was light-cured before the dual resin cement and the post were placed. Twenty Aestheti-Plus posts (white quartz fiber posts; RTD, St. Egreve, France) were used. A week after application, the root samples were extracted and processed for SEM observations. RESULTS: Both adhesive systems showed RDIZ and resin tag and adhesive lateral branch formation. In Group 2 samples, RDIZ morphology was easily detectable and uniform along root canals. Also, resin tag formation was well represented in all thirds. In group 1 samples, resin tag formation at the apical third and RDIZ formation was less evident. Statistically significant differences were found among the two groups at the apical third. CONCLUSION: The microbrush permitted a more uniform RDIZ and resin tag formation along the entire length of the canal than did the standard brush. The microbrush can be routinely used for bonding fiber posts into root canal preparations.

Adhesives↗

PubMedDate not supplied

In vitro hydrolytic degradation of composite quartz fiber-post bonds created by hydrophilic silane couplings.

The hydrolytic stability of a pre-activated MPS silane (Monobond-S) and a 2-component 4-META/ gamma-MPTS silane (Porcelain Liner M) to H202-etched quartz fiber posts was investigated using a modeling approach. Composite build-ups around silanized posts were stored dry for 24 hours, stored in deionized water at 37 degrees C for 24 hours, 1 week, 1 month or they were thermocycled. Sectioned specimens were prepared for microtensile bond testing and SEM examination; 4-META/gamma-MPTS silane produced a rapid decline in bond strength after 1 week and 1 month of water storage and after thermocycling. This was not apparent in pre-activated MPS silane. SEM revealed debonding along the post-composite interfaces, which were coupled with 2-component silane. The use of a hydrophilic resin monomer (4-META) for on-demand hydrolysis of the gamma-MPTS silane expedited interfacial water sorption and hydrolytic degradation, which may be prevented with alternative coupling strategies.

Composite Resins↗

PubMedDate not supplied

Clinical behavior of translucent-fiber posts: a 2-year prospective study.

PURPOSE: This study prospectively evaluated the clinical performance of three types of translucent posts over a follow-up period of between 2 and 3 years. MATERIALS AND METHODS: Selected were 225 patients with one premolar in need of endodontic treatment, followed by restoration with a fiber post and porcelain crown. The sample was randomly divided into three groups of 75 patients each. The same type of post was used in all patients within a group: group 1 = Aesthetic Plus; group 2 = DT; and group 3 = FRC Postec. For bonding the post, a light-curing adhesive (One-Step) and a dual-curing resin cement (Duo-Link) were applied in group 1 and 2 roots, whereas self-curing materials (Excite DSC as adhesive and MultiLink as resin cement) were used in group 3. After 6, 12, and 24 months, patients were recalled, and a clinical and radiographic examination was performed. For some patients, 30-month follow-up data were also collected. RESULTS: Debonding of the post occurrred in eight cases (3.5%); in another six cases, a recurrence of the periapical lesion was reported. CONCLUSION: The statistical analysis did not reveal any significant difference in the survival rate of the tested posts, suggesting that all are equally and sufficiently reliable for clinical use.

Adolescent↗