Kulzer GmbH Research Articles

Coverage error and shade-match accuracy in three ceramic gingival systems

Research into the coverage error (CE) of gingival systems that have been expanded by using ceramic specimens created by mixing basic colors is lacking. The purpose of this in vitro study was to compare the CEs of 3 ceramic gingival color systems that have been expanded with basic-color mixtures from a sample of 360 White participants and to classify the participants according to the accuracy of the shade match achieved with each system. L*a*b* color coordinates were recorded in 3 zones of attached gingiva for 360 White participants with healthy gingival tissue (187 men and 173 women). The CEs were calculated for 3 ceramic gingival systems that had been expanded with specimens obtained by mixing the basic colors in consecutive order, the color percentages in each mixture having been altered by 10% increments. The systems were Heraceram (Kulzer GmbH) (n=51); Vita VM9 (Vita-Zahnfabrik) (n=41); and IPS Style (Ivoclar AG) (n=41). The participants were classified into 3 groups according to how well the selected shade matched their gingival color (excellent, acceptable, or poor). The data were analyzed using a 1-way ANOVA with a randomized block design and the homogeneity of proportions test (α=.05). Statistically significant differences were found between the CEs of the 3 expanded gingival systems in the 3 zones where gingival color was measured (P<.001). The expanded Heraceram system had the smallest CE (ΔE00: minimum 2.66 in the middle zone and maximum 2.95 at the mucogingival line). In the 3 gingival zones, the expanded IPS Style system produced the largest percentage of participants with a poor shade match (ΔE00: minimum 71.4% at the mucogingival line and maximum 75.8% at the free gingival margin), while the expanded Heraceram system had the lowest percentage of participants with a poor shade match (ΔE00: minimum 33.3% in the middle zone and maximum 41.7% at the mucogingival line). The CEs calculated for the expanded Vita VM9 and IPS Style ceramic gingival color systems exceeded the clinical acceptability thresholds in the 3 zones examined. According to the ΔE00 formula, the gingival color of at least 33% of participants matched poorly with the expanded systems studied.

Effect of the Adhesive Strategy on Clinical Performance and Marginal Integrity of a Universal Adhesive in Non-Carious Cervical Lesions in a Randomized 36-Month Study.

The effectiveness of a universal adhesive applied in three application modes for the preparation of Class V composite restorations was evaluated both clinically and by quantitative marginal analysis (QMA) over 36 months. In 50 patients, three (n = 21) or four (n = 29) non-carious cervical lesions (NCCL) were restored with Venus® Diamond Flow (Kulzer GmbH, Hanau, Germany). The adhesive iBond® Universal (iBU, Kulzer, Germany) was used in self-etch (SE), etch-and-rinse (ER), or selective-enamel-etch mode (SEE). The etch-and-rinse adhesive OptiBondTM FL served as a control (OFL, Kerr GmbH, Herzogenrath, Germany). The restorations were clinically assessed (FDI criteria) at 14 days (BL), 6, 12, 24, and 36 months. Additionally, QMA was conducted on all restorations of 11 randomly selected patients. FDI criteria and marginal gap and perfect margin were compared between and within groups and recalls using McNemar, Wilcoxon, or Mann-Whitney U-tests (α = 0.05). Starting with 12 months, cumulative failure rates were lower in iBU-SE (0.0%, p = 0.016) and iBU-ER groups (2.1%, p = 0.07) compared to OFL (16.7%). At two years, iBU-SEE also showed fewer failures (0.0% SEE vs. 34.6% OFL, p = 0.016), as did iBU-SE compared to iBU-ER after 36 months (2.2 and 19.6%, p = 0.039). From BL, the iBU-SEE group always had the fewest marginal gaps and the highest percentage of perfect margins. From BL, iBU-SEE (0%, p = 0.008) and iBU-ER (0.2%, p = 0.027) showed significantly fewer marginal gaps compared to OFL (2.5%) and more perfect margins were found with iBU-SEE starting at 6 months (p = 0.054). The SEE and ER modes ensured the most excellent marginal quality, with differences from the control appearing earlier with QMA than clinically. In restoring NCCls, iBU showed superior clinical performance over OFL, especially in modes SE and SEE.

Effect of cigarettes smoke on bonded polymeric restorations: OCT study

BackgroundUp to date, the effect of cigarette smoke (CS) on the adhesive properties of the restorative materials bonded to tooth structure is still unclear. It is still questionable if it interferes with the durability and clinical success of these restorations. Few numbers of studies reported the assessment of microgaps of dental composite using cross-polarization optical coherence tomography (CP-OCT). The aim of this study was to evaluate the presence of interfacial microgaps between composite resin restoration and the tooth structure with or without exposure to CS under the CP-OCT. Materials and methodsIn this in-vitro study, a standardized round class-V cavities were prepared in twenty extracted, caries-free human molar teeth, and they were divided randomly into two groups (n = 10). Adhesive system (Gluma universal, Kulzer GmbH) was applied followed by filing the prepared cavities with flowable composite restoration (Charisma, Kulzer GmbH). Then, exposure to CS (40 cigarettes/day) was carried out for 14 days and the samples were stored in normal saline solution after each smoke exposure cycle. Next, all samples were immersed in ammoniac silver nitrate for 24 h, followed by immersion in a photo-developing solution for 8 h. Optical comparison was carried out by CP-OCT to assess microgaps percentage between smoke (SG) and non-smoke groups (NSG) at the axial walls (AW) and cavity floor (CF). ResultsIndependent T-test showed that there was a significant difference between the two groups (SG, NSG) in AW microgaps percentage (p = 0.008), while there was no difference in CF (p = 0.15) ConclusionIt can be inferred from the current finding that OCT can be used to predict the adaptability of the bonded restoration under the thermochemical influence. CS has a negative effect on the marginal integrity of the bonded polymeric restorations.

Fracture toughness of 3D printed denture teeth.

Advances in digital dentistry lead to use of three-dimensional (3D) printed resin denture teeth. Fracture toughness of these teeth must be assessed. This study aimed to compare the chipping and indirect tensile fracture resistance of denture teeth fabricated by 3D printing technique with traditionally fabricated resin denture teeth. Four groups (Gr) were made (n= 50/group): Gr-1 3D printed denture teeth (denture teeth; Formlabs Inc., Somerville, MA, USA), Gr-2 SR-Orthosit-PE (Ivoclar Vivadent AG), Gr-3 Portrait IPN (Dentsply Sirona), Gr-4 Pala Premium 8 (Heraeus Kulzer GmbH). Stereolithography 3D printing was used to create the methacrylate-based photopolymerized resin teeth models and remaining group teeth were collected commercially. A 1 mm/min chipping and indirect tensile fracture speed tests were carried out till fracture occurred. The data so obtained were statistically analysed using one-way analysis of variance with Tukey's honestly significant difference multiple comparisons test (p< 0.05). At the end of the test, the fractured areas of the specimens were evaluated by the chief researcher to assess the fracture pattern of the teeth. The indirect tensile fracture values of the 3D printed teeth were more than that of Pala Premium-8 and SR-Orthosit-PE but it was lower than that of Portrait IPN teeth. In chipping test, buccal chipping of the loaded cusp was seen in 3D printed resin without distortion and in indirect tensile test in 3D printed resin teeth, line of fracture emerges near the loading point propagates from the inner incline of both cusps and extends cervically, unlike in other groups where first deformation occurs then fracture. Prosthetic teeth fabricated by the 3D printing technique using printable resin material provide adequate fracture resistance as denture teeth.

Numerical Study of the Mechanical Behaviour of Wedge-Shaped Defect Filling Materials.

This paper deals with direct restorations of teeth with non-carious cervical lesions (NCCL). NCCL defects are capable of gradual growth and are accompanied by the degradation of the surrounding tissue. Direct restorative treatment, in which the cavity is filled with a cementing agent, is considered to be an accessible and common treatment option. The study included simulations of the teeth without lesions, the teeth with V and U lesions and the tooth-restorative system. Parameterised numerical tooth models were constructed. Two cases with defect depths of 0.8 mm and ~1.7 mm and three variants with fillet radii of the defect end of 0.1, 0.2 and 0.3 mm were considered. The effect of two biomaterials for restorations was studied, namely Herculite XRV (Kerr Corp, Orange, CA, USA) and Charisma (Heraeus Kulzer GmbH, Hanau, Germany). The models were deformed with a vertical load of 100 to 1000 N from the antagonist tooth. The tooth-restorative system was considered, taking into consideration the contact interaction in the interface areas with the tooth tissues. Within the limits of the research, the character of the distribution of the deformation characteristics and their dependence on the level of loading, the depth of the defect and the radius of the curvature of the “wedge” were established.

Microbial contamination of resin composites inside their dispensers: An increased risk of cross-infection?

ObjectivesTo evaluate the effects of microorganisms’ contamination inside the dispensing syringes of different types of resin-based composites (RBCs). MethodsThis study encompassed two sections. First, an anonymous electronic survey was submitted via Google forms to Italian dentists to acquire information about composite handling during clinical procedures. Then, a bench test was performed on nanohybrid RBCs differing in matrix chemistry and fillers [FiltekTM Supreme XTE (3MTM); Venus Pearl (Kulzer GmbH); Admira Fusion x-tra (Voco)] to evaluate the microbial viability on their surfaces with/out photocuring. Uncured RBCs were exposed to standardized inocula of Streptococcus Mutans, Candida Albicans, Lactobacillus Rhamnosus, or mixt plaque in an in vitro model reproducing clinical restorative procedures. Half of the RBC specimens were cured after exposure. Microbial viability was assessed using an MTT-based test. Statistical analysis included three-way ANOVA and Tukey's tests (p<0.05). ResultsAmong 300 dentists completing the survey, the majority declared to use the spatula to carry the RBCs from the syringe to the dental cavity (50% same spatula; 35% two spatulas). However, 80% of respondents had personal feelings that using one spatula could be a source of cross-contamination. In vitro results using one spatula showed microbial contamination of all RBCs after one hour of storage. The contamination levels depended on the used strain and RBC type (p<0.0001), but photocuring did not reduce contamination (p = 0.2992). ConclusionsMicrobial species’ viability on uncured RBCs and after photocuring shows the existence of a considerable risk of cross-infection. Clinical procedures in Restorative Dentistry need to acknowledge and to reduce such risk during RBCs handling. Clinical significanceDentists must be aware of the possibility of cross-infection during restorative procedures, especially when the same spatula is repeatedly used for placing RBC in the cavity.

Spectrophotometric evaluation of restorative composite shades and their match with a classical shade guide.

ObjectivesThe aim of this study was to verify the match between 5 shades of composites from different manufacturers with a shade guide and among the systems using a portable spectrophotometer.Materials and MethodsShade measurements were performed on specimens of Z350 XT (3M ESPE), Charisma Diamond (Heraeus Kulzer GmbH), Esthet X-HD (Dentsply Caulk), and Empress Direct (Ivoclar-Vivadent) for shades A1, A2, A3, B1, and C3 using a Vita Easyshade spectrophotometer (Vita Zahnfabrik) against a white background. Corresponding shades of Vitapan Classical (Vita Zahnfabrik) guide were measured likewise and shade variation (ΔE) was calculated based on International Commission on Illumination L*a*b* parameters. The ΔE of the composites in each shade was compared by one-way analysis of variance and Tukey's post hoc test (α = 0.05).ResultsAll composites presented ΔE > 3.7 compared with the shade guide. Variation in shades A3, B1, and C3 was significantly different for all composites. ΔE of Z350 XT was significantly lower for A1 than for the other shades, whereas ΔE of Z350 XT and Charisma Diamond were significantly lower for A2 than for the other shades.ConclusionsNo composite shade matched with the shade guide. Equivalent shades of the restorative composite from different manufacturers may show clinically noticeable ΔE.

Does a new formula have an input in the clinical success of posterior composite restorations? A chat study.

To compare the clinical behavior of a universal light-curing, ultra-fine particle hybrid composite and successor of this material in class I and II cavities after 60months. Forty patients (21 females, 19 males) with ages ranging between 18 and 38years (23.15 ± 5.15) received 80 (13 Cl I and 67 Cl II) resin composite restorations (Charisma/Charisma Classic, Kulzer GmbH) in combination with an etch and rinse adhesive system (Gluma 2Bond) under rubber dam isolation. Two experienced operators performed all the restorations. Restorations were evaluated by the other two examiners according to the FDI criteria at baseline and at 6, 12, 18, 24, 36, 48 and 60months. Surface characteristics of one restoration selected randomly were examined under a scanning electron microscope (SEM) at each recall. Data were analyzed statistically (p< 0.05). After 60months, recall rate was 90%. None of the restorations failed. Three restorations from Charisma and 4 from the Charisma Classic group showed minor surface staining. Twelve Charisma and 14 Charisma Classic restorations were scored as 2 for margin staining. Four restorations from both groups showed minor shade deviations but no significant difference was observed between the two restorative materials for any criteria evaluated after 60months (p > 0.05). SEM evaluations were in accordance with the clinical findings. Both materials exhibited clinically similar and successful performance over the 60-month observation period. A new formulation of resin composite may not always perform better clinical performances. ClinicalTrials.gov : NCT02888873.

Volumetric effects in the degradation of dimethacrylate-based polymer/filler nanocomposites: A positron annihilation study

The applicability of positron annihilation lifetime (PAL) spectroscopy to identify volumetric changes in nanostructured polymer/filler substances is first verified at the example of commercially available dimethacrylate-based dental restorative composites Charisma® (Heraeus Kulzer GmbH, Germany) affected to light-curing photopolymerization and one-year dry physical ageing. Principal channel governing PAL spectra in these nanocomposites is recognized as mixed positron-Ps trapping, where positronium Ps (i.e. bound positron-electron state) decay occurs in free-volume holes localized preferentially in polymer matrix, while free positron self-annihilation is character for interfacial voids at the surface of filler-particles assemblies in the filler and/or mixed filler-polymer environment. Methodological algorithm for experimental PAL spectra refinement referred to as the x3-x2-CDA (coupling decomposition algorithm) is validated for these nanocomposites, obeying changes in atomic-deficient structure due to direct conversion between positron-trapping and Ps-decaying sites. Straightforward parameterization of the reconstructed PAL spectra allows meaningful identification of free-volume entities responsible for nanostructurization-driven transformations.

Comparing the mechanical properties of pressed, milled, and 3D-printed resins for occlusal devices

Statement of problemComparisons of the material qualities of pressed, milled, and 3D-printed occlusal devices are sparse, complicating informed decisions on material choice. PurposeThe purpose of this in vitro study was to compare the material properties of pressed, milled, and 3D-printed resins, as well as how these are affected by thermal aging. These data were then used to estimate the likely clinical performance of the tested materials. Material and methodsThree pressed (ProBase Cold; Ivoclar Vivadent AG, Palapress clear; Kulzer GmbH, Aesthetic Blue clear; Candulor), 3 milled (Temp Premium Flexible Transpa; Zirkonzahn, idodentine PMMA transparent; Unión Dental S.A., Yamahachi PMMA clear; Yamahachi Dental MFG), and three 3D-printed (Freeprint splint; DETAX GmbH, LuxaPrint Ortho Plus; DMG GmbH, Nextdent Ortho Clear; Vertex-Dental B.V.) resin materials were evaluated. Flexural strength, Martens hardness (HM), Vickers hardness (HV), water sorption, water solubility, and surface topography were analyzed. The tests were carried out after 50 hours of water storage at 37 °C (baseline) and after simulated aging (50 hours of water storage at 37 °C, followed by 20 000 thermocycles [TC] at 5 °C and 55 °C). ResultsAt baseline, the mean flexural strength values were 92.8 to 99.5 MPa for pressed, 95.1 to 122.0 MPa for milled, and 19.5 to 91.3 MPa for 3D-printed materials. After aging, these values were 87.6 to 93.5 MPa for pressed, 93.1 to 116.0 MPa for milled, and 13.0 to 63.3 MPa for 3D-printed resins. The mean HM values were 130.1 to 134.1 N/mm for pressed and 130.3 to 158.5 N/mm for milled resins. After aging, the mean HM ranged from 121.6 to 124.2 N/mm for pressed and 116.2 to 149.7 N/mm for milled resins. The mean HV values were 18.2 to 19.9 for pressed and 18.4 to 23.0 for milled resins before aging and 16.9 to 18.7 for pressed and 17.3 to 22.3 N/mm for milled resins after aging. Printed resins could not be measured. At baseline, the mean modulus of elasticity ranged from 4.6 to 4.8 GPa for pressed and from 4.7 to 5.3 GPa for milled resins. For 3D-printed resins, only 1 material could be measured (3.7 GPa). The mean sorption values were 8.6 to 9.2 μg/mm3 for pressed, 7.9 to 10.5 μg/mm3 for milled, and 9.2 to 21.2 μg/mm3 for additive resins. After aging, these values were 21.1 to 22.6 μg/mm3 for pressed, 20.5 to 23.7 μg/mm3 for milled, and 19.4 to 45.5 μg/mm3 for 3D-printed resins. The mean solubility values ranged from 0.3 to 1.4 μg/mm3 for pressed, 0.4 to 1.7 μg/mm3 for milled, and −3.5 to 11 μg/mm3 for 3D-printed materials. ConclusionsPressed and milled resins can be considered equivalent in terms of their material properties. Relative to the pressed and milled resins, the 3D-printed resins had lower flexural strength and hardness values and higher water sorption and solubility.

Wear resistance of 3D-printed denture tooth resin opposing zirconia and metal antagonists

Statement of problemAdditive manufacturing technology can be used for denture bases and also denture teeth. Therefore, the mechanical properties of 3D-printed resin denture teeth should be evaluated. PurposeThe purpose of this in vitro study was to compare the wear resistance of 3D-printed denture tooth resin with that of conventionally prefabricated denture teeth. Material and methodsEighty substrate specimens were prepared with 5 kinds of resin denture teeth: 3D-printed denture tooth resin (DENTCA denture tooth resin; DENTCA, Inc), Artic 6 (Kulzer GmbH), Preference (Candulor AG), Premium 6 (Kulzer GmbH), and Surpass (GC Corp). The 3D-printed denture tooth specimens were made of methacrylate-based photopolymerized resin by stereolithography 3D printing. Antagonistic surfaces were made from zirconia by milling and from cobalt-chromium (Co-Cr) alloy by 3D printing and casting. The specimens were loaded at 49 N for 30 000 cycles under thermocycling conditions in a mastication simulator. Wear resistance was measured by calculating the volume of substance lost. Wear surface characteristics were observed by using a scanning electron microscope (SEM). Two-way ANOVA was used to analyze the data (α=.05). ResultsThe influence of the resin denture teeth and the type of antagonist were both statistically significant. The wear volume loss of the 3D-printed denture tooth resin was higher than that of Artic 6 and Preference when opposing the zirconia and the metal antagonists (P<.05). The 3D-printed denture tooth resin did not show a significant difference from Premium 6 with the zirconia and the metal antagonists or Surpass with the zirconia antagonist. From the SEM images, the specimens of the 3D-printed denture tooth resin showed a relatively smooth surface with the zirconia antagonist and exhibited cracks when opposed by the metal antagonist. ConclusionsThe results suggest that 3D-printing by using resin materials provides adequate wear resistance for denture tooth use.

MACROSTRUCTURE OF TEETH RESTORED WITH DIFFERENT DENTAL MATERIALS ANALYZED AFTER THERMAL INVERSION

Objective: This study aimed to investigate the macrostructure of teeth restored with different dental materials after thermal inversion. Material and methods: The sample consisted of 16 bovine mandibular incisors. Half of the teeth underwent class V restorations with amalgam (Amalgam GS 80, SDI Dental Ltd., Dublin, Ireland), while the other half was restored with composite (Charisma, Kulzer GmbH, Hanau, Germany). During 30 minutes the teeth were exposed to heating at 100 o C, 200 o C, 300 o C and 400 o C. Next, cooling was performed in half of the sample using a fan (slowly) and in the other half using water (quickly). Qualitative analysis was performed to detect eventual macroscopic alterations in the teeth, especially considering: I) the color of the restoration; II) the structure of the restoration; III) fitting of the restoration in the cavity; IV) main alteration of the restoration from the original form; V) main alteration of the tooth from the original form. Results: Different macroscopic alterations were observed after slow and quick cooling of the amalgam after heating at 200 o C, 300 o C and 400 o C, while for the composite the alterations were detected only after heating at 400 o C. Conclusion: Optimal human identification performances and forensic reports must consider the eventual macroscopic alterations in dental restorations and teeth detected in charred bodies retrieved from the water.

Light-cured dimethacrylate dental restorative composites under a prism of annihilating positrons.

Breakthrough resolutions in current biopolymer engineering rely on reliable diagnostics of atomic-deficient spaces over the finest sub-nanometer length scales. One such diagnostic is positron annihilation lifetime spectroscopy, which probes space-time continuum relationships for the interaction between electrons and their antiparticle (positrons) in structural entities like free-volume defects, vacancies, vacancy-like clusters, interfacial voids and pores, etc. This paper is intended to highlight the possibilities of positron annihilation lifetime spectroscopy as an informative instrumentation tool to parameterize free-volume evolution in light-cured dimethacrylate dental restorative composites exemplified by Charisma® (Heraeus Kulzer GmbH, Hanau, Germany) and Dipol® (Oksomat-AN Ltd, Kyiv, Ukraine). The subjects of the study were the commercially available dimethacrylate-type dental restorative composites Charisma® and Dipol®. The analysis used a fast-fast coincidence system of 230 ps resolution based on 2 photomultiplier tubes coupled to BaF2 scintillator detectors and ORTEC® (ORTEC, Oak Ridge, USA) electronics to register lifetime spectra in normal-measurement statistics evolving ~1 million coincidences. The annihilation process in both composites is identified as mixed positron-Ps (positronium) trapping, where ortho-Ps decaying is caused entirely by free-volume holes in the polymer matrix, and the 2nd component is defined mainly by interfacial free-volume holes between filler nanoparticles and the surrounding polymer. The most appropriate model-independent estimation of photopolymerization volumetric shrinkage in dental restorative composites can be done using averaged positron annihilation lifetime. Partiallyconstrained x4-term analysis of lifetime spectra is less efficient, giving greater scatter of variance with an additional artifact of fixed shortest lifetime allowing unresolved mixing in the 2nd component. A meaningful phenomenological description of transformations in Ps and positron-trapping sites under light curing, which occurs more efficiently in Charisma® than in Dipol® nanocomposites, can be developed at the basis of a semi-empirical model exploring a x3-x2-coupling decomposition algorithm. A deep understanding of void-evolution processes in dimethacrylate dental composites employing positron annihilation lifetime spectroscopy makes it possible to diagnose, characterize and engineer novel biomaterials for advanced use in medical practice.

Free Volume Structure of Acrylic-Type Dental Nanocomposites Tested with Annihilating Positrons

Positron annihilation spectroscopy in lifetime measuring mode exploring conventional fast-fast coincidence ORTEC system is employed to characterize free volume structure of commercially available acrylic-type dental restorative composite Charisma® (Heraeus Kulzer GmbH, Germany). The measured lifetime spectra for uncured and light-cured composites are reconstructed from unconstrained x3-term fitting and semi-empirical model exploring x3-x2-coupling decomposition algorithm. The governing channel of positron annihilation in the composites studied is ascribed to mixed positron-Ps trapping, where Ps decaying in the third component is caused entirely by input from free-volume holes in polymer matrix, while the second component is defined by free positron trapping in interfacial free-volume holes between filler nanoparticles and surrounded polymer matrix. Microstructure scenario of the photopolymerization shrinkage includes cross-linking of structural chains in polymer matrix followed by conversion of bound positron-electron (positronium) traps in positron-trapping interfacial free-volume voids in a vicinity of agglomerated filler nanoparticles.

Influence of post-etch cleaning and silane heat treatment on resin bond strength to silica-based leucite: an in vitro study

Adhesive cementation of bonded all-ceramic restorations is critical for their long-term clinical performance. The objective of this study was to evaluate the role of post-etch cleaning (PEC) and silane heat treatment on the micro-tensile bond strength of silica-based leucite (SBLE) ceramic when bonded to composite resin. Twenty-four blocks of SBLE ceramic (HeraCeram Press®, Heraeus Kulzer GmbH Grüner Weg 11 63450 Hanau) were fabricated and bonding surfaces were etched using 9.5% hydrofluoric acid. Six experimental groups were made from the various surface treatment combinations including: PEC (37.5% phosphoric acid for 1 min, rinsed with water for 20 s and ultrasonic bath immersion), silane application and silane heat treatment (100 °C for 5 min). An adhesive resin and a light-cured restorative composite were used to bond the ceramic and composite resin blocks under standard conditions. Three hundred and sixty specimen sticks (8 × 1 mm²) were subjected to micro-tensile testing. The means of the micro-tensile bond strength (μ-TBS) were analysed with ANOVA and Tukey–Kramer multiple comparison test. The specimens tested were assessed for mode of failure using scanning electron microscopy. The highest μ-TBS value (38.25 ± 3.40 MPa) of the specimen was achieved by PEC and heated silane. PEC and silane application showed statistically significant improvements in the μ-TBS (p < 0.01). The mean maximum difference was due to PEC (18.91 ± 3.70 MPa). In the surface treatment of SBLE ceramics, PEC had the most significant factor which affected the μ-TBS of resin composite.

Adhesion between zirconia and indirect composite resin

PurposeThe purpose of this study was to determine the bond energy using the strain energy release rate of three indirect restorative composite veneering systems to YZr. Materials and methodsThree indirect composite veneering systems (Ceramage – Shofu Inc.; Signum – Heraeus Kulzer GmbH; Sinfony- 3M ESPE) were bonded to YZr stabilized zirconia plates with and without sandblasting and manufacturer׳s recommended bonding agents per the method described by Cheng et al. [32] consisting of two opaque layers on the YZr plate at the bond surface interface and a 12mm composite rod. The specimens were brought to failure with a universal testing machine and G-values calculated. One-way ANOVA and Dunnetts׳s test (P=95%) were performed. Homogeneity of the variables was confirmed with Bartlett׳s test. ResultsNo significant difference was observed between the G-values for the control groups of Ceramage, Signum and Sinfony. Within the Ceramage group, there was no significant difference between the surface treatments. The Signum group showed a significant difference between the control and sandblasted groups as well as the sandblasted surfaces in combination with bonding agent groups, but no significant difference between control and bonding agent alone. The Sinfony group, showed no significant difference between the control and sandblasted groups, but a significant difference between the control and sandblasted with bonding agent groups (Rocatec). ConclusionThe application of acidic functional phosphate monomer MDP or silicatising the YZr surfaces before veneering with indirect composite veneering material produced higher bond energy. Sandblasting the YZr surfaces with 120 grit AlO2 only, did not increase the bond energy.

Influence of surface sealant agents on the surface roughness and color stability of artificial teeth

Statement of problemAlthough various surface sealant agents are available and recommended for chairside polishing procedures, their effect on the surface roughness and color stability of denture teeth is not clear. PurposeThe purpose of this in vitro study was to evaluate the effect of sealant agents on the surface roughness and color stability of various denture tooth materials. Material and methodsEighty disk-shaped specimens were prepared for each type of denture tooth material (SR Vivodent, PMMA; Vitapan, reinforced-PMMA; SR Phonares II, composite resin). The specimens were assigned to 4 groups according to the surface treatment used (n=20): surface sealant agents (Palaseal; Heraeus Kulzer GmbH, Optiglaze; GC Corp Biscover; Bisco Inc) and a conventional laboratory polishing technique (control group). A thermal cycling procedure was applied for half of the specimens (n=10). The surface roughness (Ra) values of thermocycled and nonthermocycled specimens were measured with a profilometer. The CIELab color parameters of both thermocycled and nonthermocycled specimens were measured with a spectrophotometer at baseline and after 7-day storage in a coffee solution. The color differences were calculated from the CIEDE2000 (ΔE00) formula. Data were statistically analyzed with 3-way ANOVA and the Tukey HSD test (α=.05). ResultsThe type of tooth material, surface treatment technique, and their interactions were significant for Ra values, and each variable and their interactions were also significant for ΔE00 values (P<.05). Thermal cycling had a significant effect only on ΔE00 values (P<.05). ConclusionsPalaseal and Optiglaze sealant agents provided smoother and more color-stable denture tooth surfaces than the conventional polishing technique. The use of the Biscover agent with SR Vivodent and Phonares II teeth increased the Ra values. The color of conventionally polished SR Vivodent and Phonares II teeth changed more with thermal cycling.

Effect of microplasmin on the clearance of vitreous haemorrhage from an experimental model in rabbits

Microplasmin is known to alter the structure of the vitreous gel. The current experiments were designed to assess its ability to enhance clearance of an experimentally induced vitreous haemorrhage, and to compare it to ovine hyaluronidase. Twenty-five rabbits were used for this experiment, divided into five groups; groups 1-3 are microplasmin-treated eyes with 25, 75 and 125 μg, respectively. Group 4 treated with 55 IU of hyaluronidase, while group 5 was treated with normal saline (control). Eyes were injected in the mid-vitreous with 0.05 ml of autologous blood obtained from the marginal ear vein. One week later, all the groups were injected with the test solution injected in mid-vitreous as stated above. Clearance of the vitreous haemorrhage was assessed weekly indirect ophthalmoscopy for 8 weeks. Microplasmin-treated eyes showed a significant clearance of the vitreous haemorrhage in a dose-dependent fashion, where group 3 (125 μg) had the highest clearance rate in comparison with control eyes. Hyaluronidase-treated eyes showed a similar clearance rate as group 3. In addition, group 3 showed a complete posterior vitreous detachment, which did not develop in hyaluronidase-treated eyes. Microplasmin may be a useful agent to accelerate the clearance of vitreous haemorrhage.

Accuracy of Implant Impressions with Different Impression Coping Types and Shapes

Accurate recording of implant location is required so that definitive restorations are properly supported and do not place additional stresses on the implants. Movement of impression copings inside the impression material using an open-tray or close-tray impression technique during clinical and laboratory phases may cause inaccuracy in transferring the three-dimensional spatial orientation of implants intraorally to the definitive cast. Consequently, the restoration may require corrective procedures. This in vitro study compared the accuracy of two different impression techniques with two different impression coping shapes using polyether impression material to obtain precise definitive casts. Two reference acrylic resin models (Technovits 4000, Heraeus Kulzer GmbH & Co., Wehrheim, Germany) with five internal connection implants having different shapes of impression copings (Implantium [Dentium, Seoul, South Korea] and Replace Select [Nobel Biocare AB, Göteborg, Sweden]) were fabricated. Twenty medium-consistency polyether impressions of these models were made with square and conical impression copings of each system using open-tray and close-tray techniques. Matching implant replicas were screwed into the impression copings in the impressions. Impressions were poured with type IV stone, and the positional accuracy of the implant replica heads in x-, y-, and z-axes (represented in [Δr]) and also rotational displacement (ΔΘ) were evaluated using a coordinate measuring machine (Mistral, DEA Brown&Sharpe, Grugliasco, Italy). These measurements (linear and rotational displacements) were compared with the measurements calculated on the reference resin models that served as control, and data were analyzed with a two-way analysis of variance at α = 0.05. Less inaccuracy occurred in less retentive shape impression copings (Replace Select) compared with the more retentive one (Implantium) (p(r) < .001 and p(Θ) < .001), but there was no significant difference between direct and indirect impression techniques (p(r) and p(Θ) > .05). The impression coping shape had more impact on impression inaccuracy than impression technique did. Understanding of the magnitude and variability of distortion when employing certain impression-making methods and impression coping shapes helps the clinician to select a better implant component and impression technique.

Retrievable Metal Ceramic Implant‐Supported Fixed Prostheses with Milled Titanium Frameworks and All‐Ceramic Crowns: Retrospective Clinical Study with up to 10 Years of Follow‐Up

The purpose of this study was to report on the outcome of metal ceramic implant-supported fixed prostheses with milled titanium frameworks and all-ceramic crowns. The clinical study included 108 patients (67 women, 41 men), mean age of 58.6 years (range: 34-82), followed between 9 months and 10 years (post occlusal loading). The mean follow-up time for all patients in the study was 5 years. A total of 125 prostheses were fabricated. The data were divided into 2 groups. Development group (DG): 52 patients with 66 prostheses (28 maxillary, 38 mandibular) fabricated with individual Procera crowns (Alumina copings, Nobel Biocare AB) and Allceram ceramics (Ducera Dental GmbH) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink ceramic (Duceram, Ducera Dental GmbH) that replicated the missing gingival tissues. Routine group (RG): 56 patients with 59 prostheses (49 maxillary, 10 mandibular) fabricated with individual Procera crowns (Zirconia copings and Nobel Rondo Zirconia Ceramic; Nobel Biocare AB) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink acrylic resin (PallaXpress Ultra, Heraeus Kulzer GmbH) that replicated the missing gingival tissues. Primary outcome measures were prosthetic survival and mechanical complications. Secondary outcome measures were biological complications testing the retrievability characteristic of the prosthesis. Survival estimates were calculated on the patient level with the Kaplan-Meier product limit estimator (95% confidence intervals [CI]). Data were analyzed with descriptive and inferential analyses. The cumulative survival rates for the implant-supported fixed prostheses were 92.4% for the DG at 10 years and 100% for the RG at 5 years (overall 96%) (Kaplan-Meier). Mechanical complications occurred in 44 patients (DG: 29 patients, 36 prostheses; RG: 15 patients, 16 prostheses); the large majority were crown fractures, occurring in 48 patients (DG: 33 patients, 36 prostheses; RG: 15 patients, 16 prostheses). In the DG, univariate analysis of logistic regression disclosed the presence of a metal ceramic implant-supported fixed prosthesis opposing dentition as a risk factor for crown fracture (OR = 1.97). Biological complications occurred in 33 patients (DG: 18 patients; RG: 15 patients), the majority being peri-implant pathologies in 19 patients (DG: 9 patients, RG: 10 patients). All situations were resolved except one in the DG that led to fixture and prosthesis loss. The results of this study indicated that, within the limitations of this study, the CAD/CAM protocol is acceptable for definitive prosthetic rehabilitation. This protocol provided these patients with a good prognosis on a middle- to long-term basis (5 years).