Lithium Disilicate Ceramic Material Research Articles

Effect Of Adhesive Application Protocols On Bond Strength Of Ceramic Veneer Thickness

Aim: The aim of this study is to evaluate Shear Bond Strength of lithium disilicate ceramic veneers usingthree adhesive application protocols (pre-curing, co-curing and no adhesive application) using two resin cements (light cure total etch and dual cure self-etch). Material and Methods: By using CAD/CAM milling machine, 42 ceramic disc samples of dimensions 4X 4 mm in diameter and 0.5mm in thickness from Lithium disilicate ceramic material (Up-cad blocks). Buccal surface of 42 premolar teeth were flattened and etched then divided into 3 groups first group(P) received bonding agent then curing, second group (C) received bonding agent with no curing, third group(N)did not receive any bonding agent. Then each group is further subdivided into two subgroups according type of cement: light-cured luting cement total etch and a dual-cured self-adhesive resin cement.. All specimen underwent thermocycling aging and then shear bond strength test was carried out. A stereo microscope wasused to measure mode of failure of each specimen. Results: Regardless of type of cement co-curing application protocol had highest bond strength, followed by Noadhesive application protocol, while pre-curing application protocol had the lowest bond strength. Regardless of adhesive application protocol Self-etch dual-cured cement had a higher bond strength than the total-etch light-cured cement. While for mode of failure statistical analysis, there was no significant difference in adhesive application protocol and cement types. Conclusions: To Increase adhesive protocol the Co-curing is better than other methods. With regards toCement types, self-etch dual cure cement gave a more reliable bond than the total etch light cure cement

Fracture load of chairside CAD-CAM veneers fabricated with pre-and fully crystalized lithium disilicate ceramics.

To evaluate the fracture load of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) veneers fabricated with two conventional pre-crystallized and two fully crystallized lithium disilicate ceramic materials. Seventy-five chairside CAD-CAM veneers (15 specimens/group) for maxillary right central incisors were fabricated with different lithium disilicate brands: (1) IPS e.max CAD; (2) Amber Mill; (3) Cerec Tessera; (4) n!ce Straumann; and (5) GC Initial LiSi Block. Restorations were cemented with resin luting cement (Variolink Esthetic, Ivoclar) to 3D-printed resin dies. Bonded restorations received 5000 thermal cycles and then were loaded until fracture. Statistical analysis included One-Way ANOVA. Conventional pre-crystallized e.max CAD displayed the highest fracture load value (640 N), followed by fully-crystallized n!ce Straumann (547 N), pre-crystallized Cerec Tessera (503 N), pre-crystallized Amber Mill (476 N), respectively; fully-crystallized GC Initial LiSi Block (431 N) displayed the lowest values. When comparing the fracture load of recent lithium disilicate ceramic material to the e.max group, which acted as the control, significant differences were noted. The LiSi Block GC group, in particular, had considerably higher mean difference values (208.867, p < 0.001, 95% CI [89.63, 328.10]), as did the Amber Mill group (164.200, p = 0.002, 95% CI [44.96, 283.44]) and CEREC Tessera group (137.533, p = 0.016, 95% CI [18.30, 256.77]). The e.max and n!ce Straumann groups had no statistically significant differences in mean scores (92.933, p = 0.198, 95% CI [-26.30, 212.17]). These findings imply that the clinical performance of recent lithium disilicate veneers varies when compared to the e.max CAD group. The fracture load of chairside CAD-CAM lithium disilicate veneers for maxillary central incisors varies according to the type of ceramic brands. Conventional pre-crystallized e.max CAD displayed higher fracture load than the recent pre- and fully-crystallized lithium disilicate materials, emphasizing the significance of choosing the right product based on the desired clinical outcome.

Challenges and Advancements in Machining Lithium Disilicate Ceramic for Dental Restorations: A Study on W-ECDM Techniques

The use of restorative techniques and trends has evolved over time. Certain material advancements have significantly transformed the field of dentistry, while some original concepts have faded into insignificance. Today, the field of dentistry continues to expand the use of all-ceramic restorations, from pressed-ceramic techniques and materials to the increasing use of zirconia and new materials derived from CAD/CAM technology. In this article, we examine the challenges of slicing lithium disilicate ceramic material using the mist flow-aided W-ECDM process. Due to its superior properties, lithium disilicate ceramic ingots are widely used in dental applications and have gained significant popularity in dental reconstruction. This paper investigates the general challenges associated with micromachining lithium disilicate ceramic ingots using the wire-ECDM process and explores how its composition contributes to these difficulties. The surface morphology of the machined material is also examined in this study.

Fracture Resistance of Chairside CAD/CAM Molar Crowns Fabricated with Different Lithium Disilicate Ceramic Materials

To compare the fracture resistance of five different groups of chairside CAD/CAM molar crowns fabricated from various lithium disilicate ceramic materials (LDC): one conventional precrystallized CAD/CAM LDC, two novel precrystallized LDCs, and one fully crystallized LDC tested both with and without optional sintering. A total of 60 chairside CAD/CAM lithium disilicate molar crowns (n = 12 per group) with 1.5-mm occlusal thickness and a 1.0-mm chamfer finish were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were divided into five groups: (1) IPS e.max CAD; (2) Amber Mill; (3) Straumann n!ce; (4) Straumann n!ce with optional sintering; and (5) Supreme CAD. Restorations were cemented using conventional resin luting cement and primer system to 3D-printed resin dies. Bonded restorations were loaded for 100,000 cycles with 275-N force, and the load at break (LB) and peak load (PL) until fracture were measured. SEM images of fracture surfaces on the printed dies were obtained. Fracture resistance was significantly different depending on the material. Supreme CAD showed the highest fracture resistance (LB: 1,557.2 N; PL: 1,785.8 N), followed by Amber Mill (LB: 1,393.0 N; PL: 1,604.2 N) and IPS e.max CAD (LB: 1,315.7 N; PL: 1,461.9 N). Straumann n!ce without (LB: 862.4 N; PL: 942.9 N) and with the optional sintering (LB: 490.4 N; PL: 541.0 N) showed significantly lower fracture resistance than the others. The fracture resistance of chairside CAD/CAM lithium disilicate molar crowns varied depending on the material, and the novel materials did not perform as well as the conventional equivalents. Fully crystallized lithium disilicate ceramic block materials showed lower fracture resistance than precrystallized counterparts and should be used with caution in the clinic, especially with optional sintering.

Impact of glazing on wear, fracture load, and optical properties of a new fully crystallized lithium disilicate ceramic material

ObjectivesLithium disilicate (LDS) based glass ceramics are indispensable materials in the field of prosthetic dentistry due to their strength and excellent esthetics. Recently, novel fully crystallized LDS for the milling process have been introduced to the market, requiring only chairside polishing before delivery. Since limited data is available about subjecting this material to glazing, this study aimed to evaluate the wear properties, fracture resistance, and optical properties of the newly introduced fully crystallized LDS after glazing. MethodsLithium disilicate glass-ceramics (fully crystallized (LiSiCAD) and partially crystallized types (EmaxCAD), of shade A3, were used in the present study. The fully crystallized specimens were subjected to a glazing firing cycle in a furnace (LiSiCAD-G) and compared to a polished fully crystallized counterpart (LiSiCAD-P, negative control) and a glazed partially crystallized LDS (EmaxCAD, positive control). Rectangular-shaped ceramic specimens (n = 10, 12 × 6.5 × 1.5 mm) and enamel antagonists were used to test the wear resistance in a specially designed wear machine built at the Department of Oral Technology, University of Bonn, Germany. The volumetric enamel loss of antagonists was measured by means of overlapping virtual 3D models derived from micro-CT scans for the teeth before and after the wear test. The weight loss of ceramic specimens in milligrams was measured after 100,000 and 200,000 wear cycles. A spectrophotometer was used to calculate the CIELAB color parameters of the ceramic specimens against black and white backgrounds to measure the translucency. Fracture resistance was also assessed after thermodynamic fatigue using a universal testing machine until fracture at a 1 mm/min crosshead speed. Statistical analysis was performed using one-way ANOVA and the significance level was set at α = 0.05. ResultsEmaxCAD and LisiCAD-G groups showed significantly higher mean ceramic weight loss after 100,000 cycles (2 ± 0.3 mg and 1.93 ± 0.2 mg, respectively) than LisiCAD-P group (0.78 ± 0.19 mg). Glazed LiSiCAD specimens demonstrated significantly higher ΔE values from shade A3 compared to polished LiSiCAD. There was no significant difference in ΔE between LiSiCAD-G and EmaxCAD. For fracture resistance, no significant difference was observed between LiSiCAD-G and LiSiCAD-P before or after aging. ConclusionsThe glazed fully crystallized LDS was superior to the partially crystallized one with regard to wear resistance but showed more color changes than the polished fully crystallized one. Furthermore, polishing of fully crystallized LDS could still be considered a better option than glazing when aesthetics is a primary prerequisite.

Effect of three different preparation designs on the marginal adaptation of indirect overlay restoration fabricated from lithium disilicate ceramic material: An in-vitro comparative study

ObjectivesMarginal adaptation is considered one of the key factors influencing the success of indirect restorations. This study aimed to estimate the marginal fit of lithium disilicate overlays with three distinct preparation designs before and after cementation. MethodsThirty maxillary first premolars were divided into the hollow chamfer design (HCD11HCD: Hollow Chamfer Design.) group,butt-joint design (BJD22BJD: Butt-Joint Design.) group, and conventional occlusal box design (COD33COD: Conventional Occlusal Design.) group (n = 10 each). The samples were scanned using an intra-oral scanner, and overlays were fabricated using computer-assisted design and milled on a computer-assisted machine. The finished restorations were luted using a self-adhesive resin RelyX Ultimate. The marginal gap was assessed using a digital microscope with 230X magnification power. Statistical analysis was conducted using analysis of varianceandposthoc(Bonferroni correction) tests, assuming a significance level of 5%. ResultsThe HCD and BJD groups recorded significantly lower marginal gap, (11.39 ± 0.72, 16.29 ± 0.75) and (11.59 ± 0.75, 16.93 ± 0.65) respectively, than the COD group (24.57 ± 1.18, 34.45 ± 1.09) both pre- and post-cementation. ConclusionThis study demonstrated that modification of tooth preparation plays a significant role in the marginal adaptation of the lithium disilicate overlays. The gap was smaller with the HCD and BJD than with the COD, with a statistically significant difference.

Retention of different all ceramic endocrown materials cemented with two different adhesive techniques.

The purpose of this in vitro study was to evaluate the influence of two adhesive techniques on the retentive force of four all ceramic endocrowns. Forty maxillary first molars of approximately similar size and shape were collected. The teeth were all decoronated 2 mm above the level of proximal cement-enamel junction (CEJ) and were all endodontically treated. The teeth were then randomly divided equally into four groups (10 each) according to all ceramic material used, as follows: Group I (VE) - Ten prepared molars were restored with hybrid ceramic (Vita Enamic); Group II (LU) - Ten prepared molars were restored with resin Nano-ceramic (Lava Ultimate). Group III (CD) - Ten prepared molars were restored with zirconia-reinforced lithium di-silicate ceramic material (Celtra Duo); Group IV (LZ) - Ten prepared molars were restored with zirconia ceramic (Lava Zirconia). Each group was then subdivided into two equal subgroups (n=5) according to the type of cement (adhesive technique) used for cementation. Subgroup A (RX ARC): the endocrowns were cemented with a total-etch adhesive resin cement (RelyX ARC). Subgroup B (RXU): the endocrowns were cemented with self-adhesive resin luting cement (RelyX UniCem). The restorations were designed with an outer cylindrical handle located on buccal and palatal surfaces to provide a mean for the removal of the endocrowns during the pull-out testing. The cemented endocrowns were thermocycled and then removed along the path of insertion using a universal testing machine at 0.5 mm/min. The retentive force was recorded, and the stress of dislodgement was calculated using the surface area of each preparation. The highest mean dislodgement stresses were 64.3 MPa for Group I (VE), whereas there was no statistically significant difference between Group I, II and III and LZ showed the lowest values with significant difference between the other three groups. Regarding the type of cement, there was a statistically significant difference between RelyX ARC (mean=60.09 MPa) and RelyX Unicem (mean=49.73 MPa). Retention of Vita Enamic, Lava Ultimate, and Celtra Duo are significantly higher than Lava Zirconia.

Evaluating the effect of repeated heat pressing on strength and hardness of a new lithium disilicate ceramic material

Evaluating the effect of repeated heat pressing on strength and hardness of a new lithium disilicate ceramic material

The aesthetic management of diastema closure treatment with indirect veneer using lithium disilicate: A case report

Background: Diastema is a space between two or more adjacent teeth that can interfere with the patient's aesthetic appearance. Various aesthetic treatments can be performed for diastema closure on anterior teeth, one of which is through the installation of veneers. The lithium disilicate ceramic material produces the thinnest veneer and has better properties than other materials, and is able to cover the anterior diastema with a fairly large width. Purpose: To describe the aesthetic procedure for closing the diastema of anterior teeth using indirect lithium disilicate ceramic veneer. Case(s): A 29-years-old male patient came with a complaint of dissatisfaction with her smile because of a gap between teeth 12 and 13. The teeth are in vital condition with normal overjet and overbite, and there are no systemic health problems. Case Management: The management of diastema closure on teeth 12 and 13 was carried out with indirect lithium disilicate veneer treatment. Lithium disilicate veneer has promising aesthetic results due to its enamel-like nature, minimally invasive because it requires minimal tooth reduction, good strength, and did not cause gingival irritation. As a result, this treatment could increase self-confidence of the patient. Conclusion: Diastema closure treatment using indirect lithium disilicate veneer is an effective treatment, gives satisfactory results and can increase the patient's confidence.

Effect of staining on the mechanical, surface and biological properties of lithium disilicate

PurposeTo simulate biodegradation and wear of stained and glazed CAD lithium disilicate ceramic, and evaluate their effects on the microbial adherence and mechanical and surface properties of lithium disilicate ceramic Materials and methods160 lithium disilicate ceramic discs were fabricated and divided in eight groups according to manual stain and glaze application with a fine paintbrush (without stain and glaze; with stain and glaze) and aging procedures (no aging; wear at 30 N load, 1.7 Hz, 3 × 105 cycles; biodegradation by exposure to microcosm biofilm; biodegradation + wear; biodegradation + wear). Profilometry was performed to determine the surface roughness and the wear consequences. Biaxial flexural strength test was performed, and a Streptococcus mutans adherence test was conducted to evaluate the number of colony forming units. ResultsUnaged samples with and without stain and glaze presented the lowest values of surface roughness (p < 0.001), but after aging (wear, biodegradation, or both), the samples in the stain and glaze groups were rougher than those in the no stain and glaze groups (p < 0.001). The stain and glaze groups showed the highest volume of wear after aging (p = 0.04), and had the lowest flexural strength values (p < 0.01), irrespective of the aging method. The aging method did not affect the flexural strength (p = 0.06). The number of colonies forming units was higher for biodegradation + no stain and glaze, biodegradation + wear + no stain and glaze, no aging + stain and glaze, biodegradation + stain and glaze, and biodegradation + wear + stain and glaze. The lowest values were observed for no aging + no stain and glaze. ConclusionThe staining and glazing of lithium disilicate increased the surface wear and bacterial adherence, and decreased biaxial flexural strength of the material. When exposed to S. mutans, surface roughness increased, and biodegradation favored bacterial adherence.

Esthetic Rehabilitation of Anterior Dentition with Different Types of Ceramic Restorations: Two Case Reports.

All-ceramic systems represent an excellent restorative alternative for fixed dental prostheses, single crowns, and veneers in the anterior dentition. With respect to improved mechanical properties, lithium disilicate ceramic material provide a broad range of indications, and extended veneers can serve as an alternative to full crowns. Although ceramic veneers represent a more conservative approach compared to crowns, the correct indication is essential to achieving the ideal outcome. The following case reports describe two types of fixed restorations of the anterior dentition: extended lithium disilicate ceramic veneers and lithium disilicate full crowns. Factors influencing treatment selection for each type of restorations are presented.

Influence of thicknesses of different ceramic materials on water sorption of light cured resin cement (in vitro study)

Aim: The aim of this research is to to study the effect of different thicknesses of three ceramic materials on the water sorption of light cured resin cements Materials and methods: A total of 60 ceramic disc specimens were divided into 3 groups according to the type of ceramic into group (E): E.max CAD, Group (V): Vita Suprinity and Group (C): Celtra Duo (n=20). Each group was subdivided into 2 groups of different thicknesses; 0.4mm and 1mm thickness. Opaque light cured Bisco resin cement specimen was made of a thickness of 0.1mm controlled using a teflon mold and cured through each ceramic specimen then inserted into the dessicator inside an incubator. The specimens were repeatedly weighed after 24h intervals using analytical balance of accuracy 0.001 g until a constant mass (m1) was obtained. The water sorption for the seven days of storage in water was calculated and the data was collected, tabulated and statistically analyzed. Results: There was a significant difference between samples of different materials (p < 0.001). The highest value was found with Emax samples (32.52±3.05) followed by Celtra Duo (24.88±2.35) while the lowest value was found with Vita Suprinity (23.36±2.39) while There was no significant difference between samples made with different thicknesses (p=0.376). Conclusion: There is a relationship between ceramic type and water sorption between the zirconia reinforced lithium silicates and lithium disilicate ceramic materials and on the other hand, different ceramic thicknesses up to 1mm did not affect the water sorption of the light cured resin cement.

Axial wall height effect on failure of adhesively luted computer assisted design/computer assisted manufactured ceramic crowns on preparations containing advanced total occlusal convergence

Computerized dentistry advocates promote that CAD/CAM adhesive technology compensates for traditional crown preparation recommendations. This study was to investigate the effect of preparation axial wall height on retention of adhesively-luted, all ceramic crowns manufactured by computerized methods. Maxillary molars were prepared with a 20 ° total occlusal convergence with preparation axial wall heights of 4, 3, 2, and 1 mm as well as an additional group containing a flat surface. The preparations were scanned with a computer acquisition device with crowns milled and prepared from a lithium disilicate ceramic material. The crowns were adhesively luted to the prepared tooth surfaces and then tested under static loading at a 45 ° angle to the tooth long axis on a universal testing machine until failure. Analysis with Kruskal-Wallis/Dunn’s found that crowns with 2, 3, and 4 mm preparation axial wall height had similar failure loads and demonstrated significantly greater failure load resistance than the zero and 1 mm axial wall height groups. However, failure mode analysis revealed that the 2 mm axial wall height group demonstrated universal adhesive failures as the zero and 1 mm axial wall height groups. Under the conditions of this study, some evidence is provided that adhesive technology may provided some compensation for less than optimal preparation features as the 3 mm axial wall height preparations demonstrated equivalent failure mode as the recommended 4 mm axial wall height preparations. However, further fatigue studies are warranted.

TRANSLUCENCY EVALUATION OF ZIRCONIA LITHIUM SILICATE AND LITHIUM DISILICATE GLASS CERAMIC WITH DIFFERENT THICKNESSES PRE AND POST CEMENTATION

OBJECTIVES: The aim of this study was to evaluate translucency of zirconia lithium silicate and lithium disilicate glass ceramic with different thicknesses, pre and post cementation. MATERIALS AND METHODS: A 120 Specimens of the current study were fabricated out of the two tested materials each counting N=60, A1 (translucent) shades of zirconia-reinforced lithium silicate glass ceramic (ZLS, Vita Suprinity, Vita Zahnfabrik, Germany) and A1(translucent) lithium disilicate glass ceramics (Rosetta SM, Korea). Specimens had a uniform rectangular shape with standard dimensions of 15 mm length and 10 mm width. Specimens of each material groups were distributed into three main groups based of specimen’s thickness 0.5mm, 1mm, 1.5mm each of these groups were further distributed into two subgroups based on translucency testing timing before or after cementation each counting 10 specimens. Specimens were fabricated by sectioning the ceramic blocks using a precision saw (IsoMet 4000, Buehler) under copious water coolant. Specimens final dimensions were confirmed with digital caliper. SPECTRO UV-Vis-Double BEAM spectrophotometer with an integrating sphere was used to evaluate the total transmittance of light as a percentage (Tt%) at a wavelength of 532 nm for comparison among groups. RESULTS: In the present study, translucency values at 0.5mm and 1 mm thicknesses LDS were higher than those recorded for ZLS at the same thicknesses. While with 1.5 mm thick specimens the translucencies of both ZLS and LDS materials were fairly similar. CONCLUSIONS: From the outcome of the current study, the following conclusions could be drawn out 1. The thinner the ceramic veneering layer, the greater will be the impact of the underlying shade on the final shade of the restoration. 2. The translucency values recorded for the translucent zirconia materials were not only almost close to those of the lithium disilicate ceramic material, but also comparable to the translucency values reported for enamel or dentin of similar thicknesses.

In vitro Fracture strength and hardness of different computer-aided design/computer-aided manufacturing inlays.

The purpose of this study was to examine the fracture strength and surface microhardness of computer-aided design/computer-aided manufacturing (CAD/CAM) materials in vitro. Mesial-occlusal-distal inlays were made from five different CAD/CAM materials (feldspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation.

The effect of five kinds of surface treatment agents on the bond strength to various ceramics with thermocycle aging

This study evaluated the effects of ceramic surface treatment agents on shear bond strengths to ceramic materials with and without thermocycling. Ceramic plates were prepared from feldspathic ceramic; AAA, lithium disilicate ceramic material; IPS e.max Press, zirconia ceramic; Lava. Ceramic surfaces were pretreated with one of five surface treatment agents (Clearfil PhotoBond mixed with Porcelainbond activator (PB), Clearfil SE One mixed with Porcelainbond activator (SO), Ceramic Primer (CP), Universal Primer (UP), Scotchbond Universal (SU)), and then a resin cement (Clapearl DC) was filled. After 0, 5,000, and 10,000 thermocycles, micro-shear bond strengths between ceramic-cement interfaces were determined. SU exhibited significantly lower initial bond strength to AAA and e.max than PB, SO, CP, and UP. For Lava, PB, SO, CP and SU exhibited higher initial bond strengths than UP. Thermocycles reduced bond strengths to all the ceramic materials with any surface treatment.

Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016).

Adherence of Streptococcus mutans on lithium disilicate porcelain specimens

Statement of problemStreptococcus mutans can adhere at restored tooth margins to cause recurrent caries. Limited information about surface quality and bacterial adherence is available for lithium disilicate ceramic materials. PurposeThe purpose of this in vitro study was to investigate how bacterial adherence is influenced by commercially available preparations of lithium disilicate ceramic materials. Material and methodsSeventeen rectangular specimens (10×10×4 mm) were fabricated for each type of lithium disilicate material: pressed (Press), milled (CAD), fluorapatite layered (ZirPress/Ceram), and glazed (Ceram Glaze). The surface roughness of each specimen was assessed before incubation with wild-type S mutans for 48 hours at 37°C with Brain Heart Infusion broth media under anaerobic conditions. Adherent bacteria were sonicated, diluted, and plated in triplicate for quantification using the plate count method to assay for colony forming units (CFUs) as an indication of bacterial viability. Statistical analysis was performed with SPSS using an analysis of variance (ANOVA) followed by the Tukey Honestly Significant Difference (HSD) test (α=.05). The Pearson r was used to evaluate the correlation between surface roughness and adherence. ResultsThe surface roughness of Ceram Glaze (1.32 ±0.19 μm) was significantly the highest, followed by ZirPress/Ceram (0.71 ±0.09 μm), which was significantly rougher than the Press (0.11 ±0.02 μm) and CAD (0.10 ±0.02 μm) groups, which were not significantly different from each other. (F=513.898, P<.001). CFUs (cells/mL) of S mutans were also significantly the highest for Ceram Glaze (61.82 ±13.76), followed by ZirPress/Ceram (28.53 ±2.40), which had significantly higher adherence than CAD (12.86 ±1.70) and Press (6.62 ±2.74), which were not significantly different from each other. (F= 201.721, P<.001). A strong positive association was found between bacterial count and surface roughness (r=.95, P<.001). ConclusionsThe surface roughness of differently prepared lithium disilicate ceramic restorations is closely related to the adherence of S mutans.

Influence of mechanical correction on surface structure of lithium disilicate ceramic material

Influence of mechanical correction on surface structure of lithium disilicate ceramic material

Evaluation of adhesive bonding of lithium disilicate ceramic material with duel cured resin luting agents.

The purpose of this vitro study was to comparatively evaluate the adhesive bonding of dual cured resin luting agents with lithium disilicate ceramic material. Porcelain laminate veneers were prepared with lithium disilicate ceramic material i.e. IPS Empress II( E-Max Press). These laminates were bonded with RelyX ARC, Panavia F 2.0, Variolink II, Duolink and Nexus NX3.The porcelain laminates were etched with 9.6% hydrofluoric acid (Pulpdent Corporation) for one minute, washed for 15 sec with three way syringe and dried for 15 sec with air syringe. The silane (Ultradent) was applied with the help of applicator tip in a single coat and kept undisturbed for one minute. The prepared surfaces of the premolars were treated with 37% phosphoric acid (Prime dent) for 15 sec, thoroughly rinsed and dried as per manufactures instructions. The shear bond test was carried out on all samples with the Universal testing machine (Instron U.S.A.) The scanning electron microscopic study was performed at the fractured interface of representative samples from each group of luting agents. In this study, the highest value of shear bond strength was obtained for NEXUS NX3 and the lowest for VARIOLINK II. The difference in bond strength can be interpreted as the difference in fracture resistance of luting agents, to which shearing load was applied during the shear bond strength test. It is inferred from this study that the composition of the luting agent determines the adhesive characteristics in addition to surface treatment and bonding surface area.