Cholinergic signalling mechanisms and early implant healing phases in healthy versus generalized aggressive periodontitis patients: A prospective, case-control study.

AIMS: Periodontal diseases negatively affect implant osseointegration. Perturbations in non-neuronal cholinergic signalling mechanisms are associated with periodontitis; however, their role in generalized aggressive periodontitis (GAgP) is unknown. The aim of this prospective case-control study was to determine the relationship between non-neuronal cholinergic signalling mechanisms, secreted Ly-6/uPAR-related protein-1 (SLURP-1), interleukin-17 (IL-17) family cytokines and healing of dental implants in health and GAgP. MATERIAL AND METHODS: Thirteen GAgP patients and seven periodontally healthy individuals (PH) were recruited. Peri-implant crevicular fluid (PICF) was obtained at baseline and 1 month post-placement. Acetylcholine (ACh) levels and cholinesterase activity were determined biochemically. SLURP-1, IL-17A and IL-17E levels were determined by ELISA. Marginal bone loss (MBL) at 1 and 6 months post-placement was determined radiographically. RESULTS: The concentration of ACh, cholinesterase activity and IL-17A levels was elevated in PICF of patients with GAgP compared to PH individuals at baseline and 1 month post-placement. The concentration of ACh and cholinesterase activity levels in PICF correlated with levels of IL-17A and MBL around implants 1 month post-placement in patients with GAgP. CONCLUSIONS: Non-neuronal cholinergic mechanisms may play a role in the aetiopathogenesis of GAgP and may directly or indirectly, through modulation of IL-17A, influence early implant osseointegration and potential long-term implant survival.

Effect of Veneering Methods on Zirconia Framework-Veneer Ceramic Adhesion and Fracture Resistance of Single Crowns.

PURPOSE: The aim of this study was to evaluate the fracture resistance (FR) and shear bond strength (SBS) via finite element analysis (FEA) of zirconia framework veneered with different methods. MATERIALS AND METHODS: Zirconia frameworks were prepared as crowns for FR and cubic blocks for SBS (N = 60, n = 10). The specimens were veneered with one of the following veneering methods: (a) overcemented file-splitting (OCF), (b) layering (L), or (c) overpressing (P). For crowns, stainless steel dies (N = 30; chamfer: 1 mm) were scanned using a contrast spray. Bilayered design for OCF and reduced design (1 mm) for both L and P were performed by computer-aided design and manufacturing. For the SBS test, zirconia blocks were sectioned (4 × 4 × 4 mm(3)) under water cooling and sintered. Frameworks were veneered with compatible ceramics for each veneering method and subjected to mechanical tests. The milled suprastructures were bonded to zirconia frameworks using a resin composite in Group OCF and photopolymerized. Crowns were cemented to the metal dies with resin modified glass-ionomer cement. All specimens were stored at 37°C, 100% humidity for 48 hours prior to mechanical tests. Data were statistically analyzed (ANOVA, Bonferroni tests, α = 0.05). Fractured specimens were examined under scanning electron microscopy (SEM), and FEA modeling of the crowns was performed. RESULTS: Mean FR values (N) were significantly higher with L (6102 ± 1519) and P (4117 ± 1083) than with of OCF (1900 ± 254) (p = 0.01). The mean SBS (MPa) in OCF (24 ± 4) was significantly lower (p < 0.002) than L (35 ± 6) and P (32 ± 6) (p > 0.05). For crown restorations, while only adhesive failures were found in OCF, cohesive failures within veneering ceramic were more frequent in P and L. FEA verified these findings. CONCLUSION: Veneering methods based on layering or pressing may reduce ceramic chipping but the overcemented file-splitting method does not seem to prevent this failure. CLINICAL SIGNIFICANCE: Layering and overpressing veneering methods on zirconia frameworks with reduced design might decrease chipping compared to overcemented file-splitting, where in the latter, zirconia framework and feldspathic suprastructure are combined using a resin cement.

Effect of different cleaning regimens on the adhesion of resin to saliva-contaminated ceramics.

PURPOSE: The aim of this study was to evaluate the influence of different cleaning regimens on the microshear bond strength (µSBS) of three different all-ceramic surfaces after saliva contamination. MATERIAL AND METHODS: Cubic ceramic specimens (3 × 3 × 3 mm(3) ) were prepared from three types of ceramics: zirconium dioxide (Z), leucite-reinforced glass ceramic (E), lithium disilicate glass ceramic (EX; n = 12/subgroup). A total of 144 composite resin cylinders (diameter: 1 mm, height: 3 mm) were prepared. Three human-saliva-contaminated surfaces of ceramic specimens were cleaned with either water spray (WS), with 0.5% sodium hypochlorite solution (HC), or with a cleaning paste (CP). Control surface (C) was not contaminated or cleaned. Composite cylinders were bonded to each surface with a resin luting cement. All specimens were stored at 37°C in deionized water until fracture testing. µSBS tests were performed in a universal testing machine (0.5 mm/min), and the results (MPa ± SD) were statistically analyzed (two-way ANOVA, Bonferroni a = 0.05). Fractured surfaces were analyzed to identify the failure types using an optical microscope at 50× magnification. Two representative specimens from all groups were examined with scanning electron microscopy. RESULTS: µSBS test results were significantly affected by the saliva cleaning regimens (p = 0.01) and the ceramic types (p = 0.03). The interaction terms between the ceramic type and saliva cleaning regimen were also significant (p < 0.05). There were no significant differences among the µSBS values (MPa ± SD) for the Z group (C = 17.5 ± 8.8; WS = 16.0 ± 4.9; HC = 17.6 ± 5.8; CP = 16.6 ± 7.5; p > 0.05). In the EX group, C resulted in significantly higher µSBS values (32.6 ± 7.4) than CP (17.4 ± 8.9), WS (15.6 ± 7.3), and HC (14.3 ± 4.5) (p < 0.05); however, C (20.4 ± 7.1) and HC (19.2 ± 7.5) showed higher µSBS values than CP (13.8 ± 4.8) and WS (10.9 ± 5.7) in the E group. Some cohesive failures within the luting resin were observed in the E and EX groups, whereas only adhesive failures were seen in zirconia groups for all surface treatments. CONCLUSIONS: Different ceramic surface cleaning regimens after saliva contamination of the zirconium dioxide revealed µSBS similar to the control group, whereas all surface cleaning regimens tested significantly decreased the bond strength values in the lithium disilicate glass ceramic. The leucite-reinforced glass-ceramic group benefited from 0.5% sodium hypochlorite solution cleaning with increased bond strengths. CLINICAL SIGNIFICANCE: Adhesive cementation of zirconia presents a clinically challenging protocol, and the cementation surface contamination of the zirconia restorations and the inadequate removal of the contaminants increase the risk of failure, as for all ceramic types. This study demonstrated that surface cleaning regimens should be applied according to different ceramic properties.

Effect of various veneering techniques on mechanical strength of computer-controlled zirconia framework designs.

PURPOSE: The objectives of this study were to evaluate the fracture resistance (FR), flexural strength (FS), and shear bond strength (SBS) of zirconia framework material veneered with different methods and to assess the stress distributions using finite element analysis (FEA). MATERIALS AND METHODS: Zirconia frameworks fabricated in the forms of crowns for FR, bars for FS, and disks for SBS (N = 90, n = 10) were veneered with either (a) file splitting (CAD-on) (CD), (b) layering (L), or (c) overpressing (P) methods. For crown specimens, stainless steel dies (N = 30; 1 mm chamfer) were scanned using the labside contrast spray. A bilayered design was produced for CD, whereas a reduced design (1 mm) was used for L and P to support the veneer by computer-aided design and manufacturing. For bar (1.5 × 5 × 25 mm(3) ) and disk (2.5 mm diameter, 2.5 mm height) specimens, zirconia blocks were sectioned under water cooling with a low-speed diamond saw and sintered. To prepare the suprastructures in the appropriate shapes for the three mechanical tests, nano-fluorapatite ceramic was layered and fired for L, fluorapatite-ceramic was pressed for P, and the milled lithium-disilicate ceramics were fused with zirconia by a thixotropic glass ceramic for CD and then sintered for crystallization of veneering ceramic. Crowns were then cemented to the metal dies. All specimens were stored at 37°C, 100% humidity for 48 hours. Mechanical tests were performed, and data were statistically analyzed (ANOVA, Tukey's, α = 0.05). Stereomicroscopy and scanning electron microscopy (SEM) were used to evaluate the failure modes and surface structure. FEA modeling of the crowns was obtained. RESULTS: Mean FR values (N ± SD) of CD (4408 ± 608) and L (4323 ± 462) were higher than P (2507 ± 594) (p < 0.05). Mean FS values (MPa ± SD) of CD (583 ± 63) and P (566 ± 54) were higher than L (428 ± 41) (p < 0.05). Mean SBS values (MPa ± SD) of CD (49 ± 6) (p < 0.05) were higher than L (28 ± 5) and P (30 ± 8). For crown restorations, while cohesive failures within ceramic and zirconia were seen in CD, cohesive failures within ceramic were found in both L and P. Results were verified by FEA. CONCLUSION: The file splitting technique showed higher bonding values in all mechanical tests, whereas a layering technique increased the FR when an anatomical core design was employed. CLINICAL SIGNIFICANCE: File splitting (CAD-on) or layering veneering ceramic on zirconia with a reduced framework design may reduce ceramic chipping.

Detection of artificial demineralization bordering different types of laminate veneers using visual inspection and storage phosphor radiography.

OBJECTIVE: The objective of this study is to compare the diagnostic accuracy of visual inspection (VI) and storage phosphor plate (SPP) radiography for the detection of artificial demineralization bordering different laminate veneers. MATERIALS AND METHODS: Twenty human maxillary canine teeth were prepared. All-ceramic (A) and hybrid ceramic (H) laminate veneers were fabricated and luted. Veneered teeth were covered except for a circular window on the proximal surface bordering restorations. Teeth were kept in acetic acid buffer to create demineralization and imaged with a SPP system. Ten observers evaluated all teeth first visually then with SPP images for the presence/absence of demineralization. Teeth were examined using scanning electron microscopy (SEM) as well. The accuracy was expressed as the area under the ROC curves (A(z)). Pair-wise comparisons were performed using two-way ANOVA and post hoc t test (p = 0.05). Fleiss kappa (κ) was used for agreement. RESULTS: SPP radiography was better than the VI for both veneers (p = 0.004). The A(z)s of two veneers were different for both VI (p < 0.005) and SPP (p < 0.005). SEM evaluation revealed lesions confined to enamel. κ was fair for H, and fair to moderate for A. Agreement was higher for the radiographic evaluation for both veneers. CONCLUSION: Enamel demineralizations bordering hybrid and ceramic laminate veneers can be detected better with SPP radiography than VI and detectability was better for all-ceramic veneers than the hybrid ceramic ones. CLINICAL RELEVANCE: Early detection of enamel demineralizations bordering laminate veneers would result in time-saving and less-invasive treatment methods; therefore, SPP radiography may be recommended in clinically suspicious cases since it provides better diagnostic accuracy.

Bond strength of metal brackets to feldspathic ceramic treated with different surface conditioning methods: an in vitro study.

PURPOSE: To compare MEP which is originally manufactured for increasing bond strength between organic resins and ceramic with conventional surface treatment methods in preparation of leucite-reinforced FC surfaces regarding shear bond strength (SBS) of stainless steel brackets and the mode of bond failure. MATERIALS AND METHODS: Forty specimens that were fabricated from FC material and glazed were randomly assigned to four surface conditioning methods: (1) CoJet Sand; (2) MEP; (3) HF acid etching followed by silane coupling agent; (4) Diamond bur followed by silane coupling agent. The SBS was determined using universal testing machine. Bond failure sites were classified according to Adhesive Remnant Index (ARI). RESULTS: No statistically significant difference (p less than 0.05) was found in SBS between the groups while significant intergroup differences were detected concerning ARI scores (p less than 0.001). Group 1 had ARI score 1 and 2 indicating mode of failure at the adhesive interface with greater percentage of the adhesive left on bracket base. The other groups had higher frequency of ARI score 3 and 2. The quantity of the ARI retained on the ceramic surface was highest in Group 3, followed by Group 4 and Group 2. CONCLUSION: MEP can be a suitable alternative for bonding metal brackets to FC surface.

Bond strength comparison of amalgam repair protocols using resin composite in situations with and without dentin exposure.

The replacement of defective amalgam restorations leads to loss of tooth material and weakens the tooth, creating an increased risk of cusp fracture. The repair of such defects is a minimal intervention technique. The current study compared the repair bond strengths of a resin composite to amalgam and an amalgam-dentin complex after various surface conditioning methods. The specimens (N = 50) consisted of sound human canines with cylindrical preparations (diameter: 2.3 mm, depth: 3 mm) with amalgam-dentin complex (N = 30, n = 10/per group) and two groups with amalgam only (N = 20, n = 10/per group). The teeth were embedded in auto-polymerized polymethylmethacrylate (PMMA). The preparations were filled with non-Gamma 2 amalgam. The enamel was removed to expose dentin. The specimens with the amalgam-dentin complex were randomly assigned to one of the following conditioning methods: Group 1: Silicacoating amalgam, etching dentin, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both; Group 2: Etching dentin, silicacoating amalgam, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both and Group 3: Etching dentin, primer/bonding on dentin, opaquer, resin composite. The specimens with only amalgam were assigned to one of the following conditioning methods: Group 4: Silicacoating, silane application, opaquer, resin composite and Group 5: Opaquer, resin composite. For the two control groups, where no dentin was involved (Groups 4 and 5), bonding was achieved only on amalgam and Group 5 had no conditioning. The specimens were kept in water at 37 degrees C for five weeks before bond strength (MPa +/- SD) testing (Universal Testing Machine). After debonding, the failure types were analyzed. The results were significantly affected by the surface conditioning method (ANOVA). Only dentin conditioning (Group 3) showed the highest bond strength (39.9 +/- 14). The unconditioned control group (Group 5) showed the least favorable results (1.4 +/- 0.5). Multiple comparisons (Tukey-Kramer adjustment) showed that the mean values of Group 1 (34.1 +/- 11.4), 3 (39.9 +/- 14) and 4 (35.5 +/- 4) were not significantly different (p > 0.05), but between Groups 2 (22.8 +/- 6.6) and 3 (39.9 +/- 14), significant differences were observed (p = 0.0027). For reliable repair of amalgam restorations, including dentin fractures, the amalgam surface should first be silica coated, then the dentin/enamel should be etched, washed and rinsed thoroughly. Finally, the amalgam should be silanized and primer/bonding applied onto the dentin.

Comparison of two bond strength testing methodologies for bilayered all-ceramics.

OBJECTIVES: This study compared the shear bond strength (SBS) and microtensile (MTBS) testing methodologies for core and veneering ceramics in four types of all-ceramic systems. METHODS: Four different ceramic veneer/core combinations, three of which were feldspathic and the other a fluor-apatite to their respectively corresponding cores, namely leucite-reinforced ceramic ((IPS)Empress, Ivoclar), low leucite-reinforced ceramic (Finesse, Ceramco), glass-infiltrated alumina (In-Ceram Alumina, Vita) and lithium disilicate ((IPS)Empress 2, Ivoclar) were used for SBS and MTBS tests. Ceramic cores (N=40, n=10/group for SBS test method, N=5 blocks/group for MTBS test method) were fabricated according to the manufacturers' instructions (for SBS: thickness, 3mm; diameter, 5mm and for MTBS: 10 mm x 10 mm x 2 mm) and ultrasonically cleaned. The veneering ceramics (thickness: 2mm) were vibrated and condensed in stainless steel moulds and fired onto the core ceramic materials. After trying the specimens in the mould for minor adjustments, they were again ultrasonically cleaned and embedded in PMMA. The specimens were stored in distilled water at 37 degrees C for 1 week and bond strength tests were performed in universal testing machines (cross-head speed: 1mm/min). The bond strengths (MPa+/-S.D.) and modes of failures were recorded. RESULTS: Significant difference between the two test methods and all-ceramic types were observed (P<0.05) (2-way ANOVA, Tukey's test and Bonferroni). The mean SBS values for veneering ceramic to lithium disilicate was significantly higher (41+/-8 MPa) than those to low leucite (28+/-4 MPa), glass-infiltrated (26+/-4 MPa) and leucite-reinforced (23+/-3 MPa) ceramics, while the mean MTBS for low leucite ceramic was significantly higher (15+/-2 MPa) than those of leucite (12+/-2 MPa), glass-infiltrated (9+/-1 MPa) and lithium disilicate ceramic (9+/-1 MPa) (ANOVA, P<0.05). SIGNIFICANCE: Both the testing methodology and the differences in chemical compositions of the core and veneering ceramics influenced the bond strength between the core and veneering ceramic in bilayered all-ceramic systems.

Influence of surface treatment on the resin-bonding of zirconia.

OBJECTIVE: To compare the effect of various surface treatments on the bonding of luting resin cements to zirconia under four-point bending. METHODS: Bar specimens (n = 200) (2 mm × 5 mm × 25 mm) were prepared from zirconia blocks (VITA In-Ceram YZ, Vita Zahnfabrik) with the cementation surface (2 mm × 5 mm) of groups of 40 treated in one of five ways: airborne particle abrasion with 50µm Al2O3 (GB), zirconia primer (Z-Prime Plus, Bisco) (Z), glaze ceramic (Crystall.Glaze spray, Ivoclar Vivadent) + hydrofluoric acid (GHF), fusion glass-ceramic (Crystall.Connect, Ivoclar Vivadent) (CC), or left untreated as control (C). Within each treatment, bars were cleaned ultrasonically for 15 min in ethanol and then deionized water before bonding in pairs with one of two luting resins: Panavia F 2.0, (Kuraray) (P); RelyX U-200 (3M/Espe) (R), to form 10 test specimens for each treatment and lute combination. Mechanical tests were performed and bond strengths (MPa) were subject, after log transformation, to analysis of variance, Shapiro-Wilk and Holm-Sidak tests; also log-linear contingency analysis of failure mode distribution; all with α = 0.05. Fracture surfaces were examined under light and scanning electron microscopy. RESULTS: While the effect of surface treatment was significant (p = 1.27 × 10(-9)), there was no detected effect due to resin (p = 0.829). All treatments except CC (30.1 MPa ×/÷ 1.44)* were significantly better than the untreated control (24.8 MPa ×/÷ 1.35) (p = 3.28 × 10(-9)). While the effect of GB - which gave the highest mean strength (50.5 MPa ×/÷ 1.29) - was not distinguishable from that of GHF (39.9 MPa ×/÷ 1.29) (p = 0.082), it was significantly better than treatment with either CC or Z (33.1 MPa ×/÷ 1.48) (p < 0.05). (* After log transformation for analysis and back; asymmetric error bounds as s.d. in log values.) SIGNIFICANCE: The novel test method design, which has good discriminatory power, confirmed the value of gritblasting as a simple and effective treatment with low operator hazard. It gave the highest bond strengths regardless of the cement type. Glaze layer application followed by hydrofluoric acid-etching on zirconia before cementation might be viable for adhesive zirconia cementation, but represents a much greater hazard as well as having problems with thickness control.