Long-Term Bonding Performance of One-Bottle vs. Two-Bottle Bonding Agents to Lithium Disilicate Ceramics.

The aim of this study was to compare the long-term bonding performance to lithium disilicate (LDS) ceramic between one-bottle and two-bottle bonding agents. Bonding performance was investigated under these LDS pretreatment conditions: with hydrofluoric acid (HF) only, without HF, with a two-bottle bonding agent (Tokuyama Universal Bond II) only. Shear bond strengths between LDS and nine resin cements (both self-adhesive and conventional adhesive types) were measured at three time periods: after one-day water storage (Base), and after 5000 and 20,000 thermocycles (TC 5k and TC 20k respectively). Difference in degradation between one- and two-bottle bonding agents containing the silane coupling agent was compared by high-performance liquid chromatography. With HF pretreatment, bond strengths were not significantly different among the three time periods for each resin cement. Without HF, ESTECEM II and Super-Bond Universal showed significantly higher values than others at TC 5k and TC 20k when treated with the recommended bonding agents, especially at TC 20k. Difference in degradation between one- and two-bottle bonding agents containing the silane coupling agent was compared by high-performance liquid chromatography (HPLC). For both cements, these values at TC 20k were also not significantly different from pretreatment with only Tokuyama Universal Bond II. For LDS, long-term bond durability could be maintained by pretreatment with Tokuyama Universal Bond II instead of the hazardous HF.

3D printing of ultra-thin veneers made of lithium disilicate using the LCM method in a digital workflow: A feasibility study.

OBJECTIVE: This article highlights the feasibility of the additive fabrication of ultra-thin veneers made of lithium disilicate using the lithography-based ceramic manufacturing (LCM) method. CLINICAL CONSIDERATIONS: An esthetical appealing restoration of anterior teeth with thin ceramic veneers is considered one of the ultimate challenges in restorative dental prosthetics. These sophisticated restorations can be fabricated in different ways. Both analog and digital subtractive manufacturing processes have been used to date. Either of the methods is highly demanding for the dental technician and dental engineering due to the required low ceramic layer thickness. CONCLUSION: Modern additive manufacturing methods, for example LCM technology, enable the production of ultra-thin lithium disilicate veneers with layer thicknesses of down to 0.2 mm and could therefore represent a viable alternative for this indication in the future. CLINICAL SIGNIFICANCE: Digital technologies can help streamline workflows, make the outcome more predictable and reproducible, and even further optimize therapeutic restorative options such as highly esthetic veneers for anterior teeth. The reduced material thickness allows for a true non-prep solution or minimally invasive preparation.

Influence of lithium disilicate pretreatment using photodynamic therapy, non-thermal plasma, and laser treatment on surface roughness and bond strength.

AIMS: To assess the shear bond strength (SBS) and surface roughness (Ra) of lithium disilicate ceramic (LDC) after using different pretreatment methods i.e., Non-Thermal Plasma (NTP), self-etching ceramic primer (SECP), curcumin photosensitizer (CP), Er and Cr: YSGG lasers (ECL) in comparison to hydrofluoric acid + Silane (HF + S). MATERIALS AND METHODS: A total of fifty LDC discs were prepared. All the discs were arbitrarily divided into five groups based on the surface conditioning used (n = 10). Group 1: PDT+S, group 2: HF+ S, group 3: NTP + S, group 4: SECP, and group 5: ECL+ S. A confocal optical microscope was used to calculate Ra for each sample. A self-adhesive resin cement was applied followed by LED light curing. A universal testing machine was used to assess SBS and a stereomicroscope was used to determine the failure mode. Two-way analysis of variance (ANOVA), and a Tukey post hoc test was used to analyze data (p = 0.05). RESULTS: The highest bond integrity of resin luting bonded to conditioned LDS ceramics were presented by group 2 (HF+ S) (21.48±1.39 MPa) and lowest by group 1 (CP+S) (13.01±1.19 MPa) respectively. Intergroup comparison analysis revealed that group 1(13.01±1.19 MPa) and group 3 (14.28±0.62 MPa) displayed comparable outcomes of bond integrity(p>0.05). Similarly, it was observed that group 2 (21.48±1.39 MPa) and group 5 (21.31±1.85 MPa) exhibited comparable values of bond strength(p>0.05). Specimens conditioned with HF+ S showed the highest Ra (1445.86±0.019 µm). However, discs treated with SECP exhibited the lowest Ra (0139.76±0.081 µm). CONCLUSION: Er, Cr: YSGG laser retains the ability to be used as an LDC surface conditioner as an alternative to HF+ S.Both the methods of pretreatment results in high surface roughness of LDC.

Influence of resin removal treatments on the surface topography and strength of de-bonded lithium disilicate ceramic.

AIM: This study aims to assess the influence of resin removal treatment regimes on the surface topography and compressive strength of de-bonded ceramic surfaces. MATERIAL AND METHODS: Sixty-five lithium disilicate ceramic (LDC) discs were prepared, cleaned, and polished with carbide paper. All samples were etched using 9.6% hydrofluoric acid (HFA). Fifteen samples were taken as positive controls; the remaining 50 samples were subjected to the process of silanization. Resin build-up using dual-cure cement was performed incrementally and light cured. Based on different methods of resin cleaning from de-bonded LDC, the samples were divided into five groups, n=10 each: group 1 (no treatment), group 2 (slow-speed diamond bur), group 3 (1 min heat treatment), Group 4 (6 min heat treatment), and group 5 (sandblasting with Al2O3). Following resin removal, LDC samples were tested under compressive failure load in a universal testing machine. Five disc specimens from each group were sputter coated with gold for scanning electron microscopy (SEM). Analysis of variance (ANOVA) and Tukey's post hoc test was used for descriptive statistics. Level of significance was established at p<0.05. RESULTS: The highest compressive strength with significant difference among all experimental groups was found in group 5 (321.54 ± 13.25 MPa) (p<0.05). The lowest compressive strength values, presenting significant difference compared with all other groups, were displayed in group 1 (158.57 ± 5.22 MPa) (p<0.05). Compressive strength among group 2 (231.54 ± 15.55 MPa), group 3 (237.81 ± 10.81 MPa), and group 4 (255.53 ± 8.95 MPa) specimens was statistically comparable (p>0.05). On SEM, heat-treated specimens confirmed coarser granules, with mild porosities and roughening, whereas sandblasted specimens exhibited consistent evenness with moderate porosity and loss of glazed surface. CONCLUSION: De-bonded LDC surface, treated with heat treatment and sandblasting procedures, exhibited removal of residual resin and significantly high compressive strength compared with non-cleansed ceramic surface.

Lithium di silicate ceramic surface treated with Er,Cr:YSGG and other conditioning regimes bonded to orthodontic bracket.

AIM: To assess bond integrity and modes of failure of metallic brackets to lithium disilicate ceramics (LDC) conditioned with Er,Cr:YSGG laser (ECL). MATERIAL AND METHODS: Sixty LDC were arbitrarily allocated into six groups (n = 15) according to the type of ceramic surface conditioning treatment. Group 1 surface treated with silane (S) only, group 2 surface etched with hydrofluoric acid (HF)+ S, group 3 surface conditioned with HF+ ultrasonic bath (UB)+ S, group 4 sand blasting (SB) of glass ceramic surface with 50 µm Al2O3, group 5 surface conditioned with self-etch ceramic primer (SECP) and in group 6 surface treated with ECL + S. After conditioning, the specimens were positioned in a universal testing device for shear bond strength (SBS) testing. Adhesive Remnant Index (ARI) was used to determine sites of bond failure. Among experimental groups analysis of variance (ANOVA) and Tukey multiple comparison test was used at a significance level of (p < 0.05). RESULTS: The highest SBS values were observed in group 3 HF+ UB + S (18.21 ± 1.241) and the lowest SBS values were displayed group 1 surface treated with S only (5.21 ± 0.23). Specimens surface conditioned in group 2 with HF+ S (17.85 ± 1.25), group 3 HF+ UB + S (18.21 ± 1.241) and group 6 ECL + S (17.09 ± 1.114) unveiled comparable SBS values (p > 0.05). CONCLUSION: LDC conditioned with ECL at (4.5 W and 30 Hz) has a potential to be used in clinical settings alternate to HF acid.

Effects of the different materials and thicknesses on endocrown stress distribution / 口腔疾病防治

Objective@#To analyze the effects of different restorations and the thickness of the occlusal space on the stress distribution of endodontically treated molars with endocrowns.@*Methods @# The finite element model of the restoration of the first mandibular molar was created, and four different endocrown materials were used including two resin based ceramics (Lava Ultimate, Vita Enamic), one lithium disilicate ceramic (IPS e.max CAD) and one zirconia ceramics (Cercon), and four kinds of surface space thickness were designed: 1 mm, 2 mm, 3 mm and 4 mm. A total of 600 N was loaded to simulate the maximum bite force in the vertical and inclined directions, and the finite element software ANSYS 10.0 was used to analyze the stress distribution@*Results@#The vertical loading analysis showed that the crown stress of the 1 mm-Cercon group was the highest at 211.30 MPa, and that of the 4 mm-Lava Ultimate group was the lowest at 11.56 MPa; the highest dentin stress was 38.84 MPa in the 3 mm-Lava Ultimate group, and the lowest was 11.68 MPa in 1 mm-Cercon group. The stress in the periodontal ligament and alveolar bone had little change. The inclined loading analysis showed that the crown stress of the 1 mm-Cercon group was the highest at 78.73 MPa and that of the 1 mm-Lava Ultimate group was the lowest at 35.51 MPa; the highest dentin stress was 41.63 MPa in the 1 mm-Cercon cervical group, and the lowest was 10.81 MPa in the 4 mm-Cercon coronal group. The stress concentration of cement and cervical dentin under inclined loading was higher than that under vertical loading.@* Conclusion @# The results of finite element analysis show that the elastic modulus of the endocrown increases, the stress of the crown restoration shows an upward trend, and the stress in the tooth shows a downward trend. With increasing crown thickness, the stress of the crown prosthesis decreased.

Color stability of polymer-infiltrated-ceramics compared with lithium disilicate ceramics and composite.

OBJECTIVE: To investigate the color stability of hybrid ceramics and to compare it to composite and lithium disilicate ceramics. MATERIALS AND METHODS: One hundred eighty samples were fabricated and processed with a semiautomatic grinding and polishing device (final step: 1200 grit). After thermocycling, samples were immersed in a staining solution (five subgroups: water, red wine, curry, black tea, cola) for 4 weeks. A spectroradiometer was used to determine the color of the samples in CIE L*a*b*. Color measurements were performed before staining (baseline, initial color), after thermocycling, after 2 and 4 week storage in staining solution and each after a two stage repolishing approach. Discoloration of specimens was calculated by means of ΔE00 compared to baseline values. RESULTS: All factors (material, staining solution, aging stage) were significantly associated with the extent of discolorations (P < .001). Maximum color changes occurred after 28 days staining (EN: ΔE00 = 4.5 ± 4.0; GB: ΔE00 = 5.0 ± 4.5; LS: ΔE00 = 3.0 ± 2.3) clearly exceeding the 50:50 threshold for acceptable color deviations. Due to repolishing, discoloration of LS samples was almost completely eliminated (ΔE00 = 0.4 ± 0.3) and significantly reduced for the other two materials (EN: ΔE00 = 1.0 ± 0.9; GB: ΔE00 = 0.9 ± 0.4; P = .428). CONCLUSION: Discoloration of hybrid ceramics ranged in-between lithium disilicate and composites, however more comparable to composites. Repolishing could reduce discolorations substantially. CLINICAL RELEVANCE: This study should help dental practitioners to estimate the color stability of common dental materials and the effect of polishing in removal of discolorations.

Photosensitization of lithium di-silicate ceramic by Er, Cr: YSGG and fractional carbon dioxide laser bonded to orthodontic bracket.

AIM: To evaluate the shear bond strength (SBS) and modes of lithium disilicate ceramics (LDC) photosensitized by Er,Cr:YSGG (ECL) and fractional carbon dioxide (CO2) laser bonded to metallic bracket compared to traditional conditioning methods. MATERIAL AND METHOD: Fifty LDC discs were polished and randomly allocated into 5 groups (n = 10) each. Group 1 were photosensitized with ECL + Silane (S). Group 2 were irradiated using CO2 laser + S. In group 3 LDC discs were treated with aluminium trioxide (Al2O3) air abrasion (AA). Moreover, samples in group 4 and 5 were conditioned with Hydrofluoric acid (HFA)+ S (Control) and Self-Etch Glass Ceramic Primer (SEGCP). Following conditioning regimen fifty maxillary central incisor brackets were pasted on LDC using adhesive material. SBS testing was performed by mounting the specimens on a universal testing machine. After debonding, sheared surface was examined under stereomicroscope to classify failure mode using adhesive remnant index (ARI). Mean and standard deviation (SD) were compared by analysis of variance (ANOVA) and Tukey multiple comparison test at a significance level of p = 0.05. RESULTS: Among the conditioning groups the highest SBS values were presented by HFA + S (21.08 ±â€¯1.06). The lowest SBS values were displayed by AA Al2O3 (12.61 ±â€¯0.45). SBS of samples conditioned with SEGCP showed significant difference amongst all experimental groups (16.76 ±â€¯0.81). CONCLUSION: LDC photosensitized with CO2 and ECL has a potential to be recommended in clinical settings alternate to HFA + S when bonded to metallic bracket.

Clinical Evaluation of Three Types of CAD/CAM Inlay/ Onlay Materials After 1-Year Clinical Follow Up.

OBJECTIVE: To evaluate the clinical performance and the marginal adaptation of inlay/ onlay restorations made of lithium of a new lithium disilicate strengthened, lithium alumino-silicate glass-ceramic (LAS) material compared with a conventional lithium-disilicate glass-ceramic (LDS) and new-generation polymer-based CAD/CAM resin composite (CS) materials over one year. MATERIALS AND METHODS: Seventy-five inlay-onlay restorations were placed in 35 patients. The restorations were assigned and randomized to three groups as LDS, LAS, and CS. Clinical evaluations were performed after one week, six months, and one year after the cementation, according to the modified United States Public Health Services (USPHS) criteria. The marginal quality analyses of 21 samples (n=7) were assessed under a scanning electron microscope. The data were analyzed by using Friedman, Wilcoxon Signed Ranks, Chi-square and Paired t-tests (p⟨0.05). RESULTS: No statistically significant difference (p⟩0.05) was found between groups in the modified USPHS, gingival index, and plaque index evaluations, and the total success rate was 100% for three groups after one year. Following SEM evaluations in all groups, continuous margin percentages were decreased, but these results were not statistically significant (p⟩0.05). CONCLUSIONS: Lithium disilicate-strengthened lithium aluminosilicate glass-ceramics can be considered a reliable material for an option for posterior onlay/inlay restorations.

Efficacy of Various Surface Treatments on the Bonding Performance of Saliva-contaminated Lithium-Disilicate Ceramics.

PURPOSE: To investigate the efficacy of different ceramic surface cleaning methods after saliva contamination on the resin bond strength to lithium disilicate ceramics. MATERIALS AND METHODS: 300 e.max CAD blocks (Ivoclar Vivadent) were polished with 600-grit silicon carbide paper and divided into five groups with or without human saliva contamination and according to the surface treatment performed (n = 10); control: no pretreatment; MP: Monobond Plus; PA+MP: 37% phosphoric acid (PA) followed by MP; HF+MP: 5% hydrofluoric acid (HF) followed by MP; MEP: Monobond Etch & Prime. The specimens were bonded with one of three resin cements: Variolink Esthetic DC (VE), Multilink Automix (MA) and Speed CEM (SC). After 24-h water storage, tensile bond strength (TBS) was measured. The ceramic surfaces after pretreatment were analyzed using x-ray photoelectron spectroscopy (XPS). RESULTS: XPS analysis showed similar elemental distributions between saliva contamination vs no saliva in PA, HF, and MEP. The TBSs were significantly influenced by surface treatments (p < 0.05). HF+MP and MEP showed statistically non-significantly different bond strengths to saliva-contaminated HF+MP and MEP, but were different from MP and saliva-contaminated MP. The TBSs after 24 h were significantly higher in HF+MP and MEP groups with VE. HF+MP and MEP did not show statistically significant differences among any groups with or without saliva contamination. CONCLUSION: Surface treatments with PA or HF followed by silane or by MEP alone were effective in removing saliva contamination and enhancing the resin bond strength.

Effect of Surface Cleaning Regimen on Glass Ceramic Bond Strength.

This study investigated the effect of saliva contamination on chemical changes of ceramic surface as well as the influence of saliva cleaning methods on ceramic-resin bond strength. Saliva was used to contaminate leucite (LGC) and lithium disilicate (LDGC) glass ceramic surfaces. The following cleaning methods were tested: water spray, cleaning with orthophosphoric acid, universal cleaning paste, ultrasonic cleaning with water, re-etching with hydrofluoric acid. Non-contaminated ceramic sample served as control. Chemical analysis of ceramic surfaces was performed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Shear bond strength (SBS) of ceramics to resin material was tested after 24-hour water storage and after thermocycling. The most effective cleaning method of saliva-contaminated ceramic surface was cleaning LGC surface with orthophosphoric acid or re-etching the LDGC surface with hydrofluoric acid. The application of the following methods resulted in obtaining reliable bond strength.

Efficacy of phototherapy with different conventional surface treatments on adhesive quality of lithium disilicate ceramics.

AIM: The aim of the present study was to evaluate shear bond strength (SBS) of LDC and resin composite in combination with phototherapy and different ceramic surface treatments. MATERIALS AND METHOD: Forty Lithium Disilicate Glass Ceramic (LDC) disks measuring (4 × 4 x 9 mm) were fabricated. The specimens were randomly divided into four groups (n = 10 each) according to the surface treatment. Group 1 H F + Silane (Control); Group 2 HF + Ultrasonic bath + Silane; Group 3 SECP (Self etch ceramic primer) and Group 4 phototherapy (Er, Cr: YSGG) + Silane. On each ceramic disk a resin build-up was done. For SBS the specimens were subjected to increasing load with a transversal velocity of 1 ml/min on a universal testing machine on a ceramic resin interface. Failure mode was evaluated using digital microscope. The failure modes were divided into adhesive, cohesive and admixed interface. Data through bond strength testing was tabulated using statistical program for social science (SPSS). Means and standard deviations were compared using analysis of variance and Tukey's post hoc test (p < 0.05). RESULTS: The maximum and minimum bond strength was observed in group 2 [19.58(1.011)] and group 1 [17.14(1.122)] respectively. The bond strength among experimental group 1 [17.14 (1.122)] and group 4 [17.48(1.145)] were found to be comparable. Specimens in Group 2 displayed significantly higher bond strength among all experimental groups. Commonly adhesive failure mode was observed in the present study, with an incidence of 60%, 100% and 70% in groups 1,2 and 3 correspondingly. CONCLUSION: Phototherapy using laser at frequency 30 Hz and 4.5 W can be used as a surface conditioner for LDC alternate to HF acid. Conditioning of LDC using Self-etch ceramic primer showed better SBS outcomes as compared to phototherapy (Er, Cr: YSGG laser).

Physico-mechanical properties of resin cement light cured through different ceramic spacers.

The purpose of this in vitro study was to compare the micro hardness, color stability/ΔE, and degree of conversion/DC of a resin cement light cured through different ceramic spacers. Lithium-disilicate ceramic samples were obtained from IPS E-max CAD blocks (HT A1) and IPS in-Ceram (transparent neutral); and divided in 7 groups (n = 8 for each test): CTR/control group; 06 M/0.6 mm monolithic; 12 M/1.2 mm monolithic; 20 M/2.0 mm monolithic; 06B/0.4 + 0.2 mm bilayered; 12B/1.0 + 0.2 mm bilayered; 20B/1.8 + 0.2 mm bilayered. The resin cement (Variolink veneer) was light cured through the ceramic spacers. The resin cement samples were evaluated for ΔE using a spectrophotometer after 24 h, 7days and after aging (24 h in water at 60 °C). Knoop microhardness and DC tests were conducted immediately after light curing, after 24 h and 7days. All experimental groups showed similar microhardness values, although being lower than CTR group. Similar results were observed after 7days. ΔE was similar between all groups after 24 h (except for 12B and 20B), and increased for all groups after 7days and after artificial aging, especially for thicker and bilayer groups. Only 06 M showed values similar to CTR group. DC values were similar to all groups immediately after light curing, increasing after 24 h and 7days. After 7days, only group 20B showed lower DC than CTR group. A tendency of higher DC could be observed for monolithic and thinner ceramics. All test results showed strong correlation (0.9987). Ceramic interposition can reduce mechanical and physical properties of resin cements, especially with thicker and bilayered ceramics. Group 06 M showed the best ΔE overtime.

Effect of Different Surface Treatments on the Tensile Bond Strength to Lithium Disilicate Glass Ceramics.

PURPOSE: To evaluate the influence of different surface treatments of lithium disilicate glass ceramics on the bonding efficacy of three luting composites. MATERIALS AND METHODS: A total of 450 blocks of e.max CAD (Ivoclar Vivadent) ground with 600-grit silicon carbide paper were prepared and divided into three groups (n = 150) according to the composite cements used: Variolink Esthetic DC (VE), Multilink Automix (MA), and SpeedCEM (SC). Each group was further divided into five subgroups (n = 10) according to the surface treatment performed: no treatment (control), Monobond Plus (MP), 37% phosphoric acid and Monobond Plus (PA), < 5% hydrofluoric acid and Monobond Plus (HF), and Monobond Etch & Prime (ME). All treated ceramic specimens were bonded with three composite cements and light cured. After 24-h water storage and 5000 or 10,000 thermocycles, tensile bond strength (TBS) was measured. The specimens underwent failure mode analysis. The results were statistically analyzed using two-way ANOVA and t-tests with Bonferroni correction. RESULTS: The TBSs were significantly influenced by surface treatments (p < 0.05). There were no significant differences in HF and ME among most of the groups. Furthermore, ME showed the highest bond strength with MA after 10,000 thermocycling. Most specimens of the ME groups exhibited cohesive failures, whereas a combination of adhesive failures and mixed failures were observed in control, MP, PA, and HF groups. CONCLUSION: In the surface treatment of lithium disilicate glass ceramics, Monobond Etch & Prime was found to be a possible substitution for the combination of hydrofluoric acid and Monobond Plus.

Fracture Resistance of Lithium Disilicate Ceramics Bonded to Enamel or Dentin Using Different Resin Cement Types and Film Thicknesses.

PURPOSE: To investigate the influence of cement film thickness, cement type, and substrate (enamel or dentin) on ceramic fracture resistance. MATERIALS AND METHODS: One hundred extracted human third molars were polished to obtain 50 enamel and 50 dentin specimens. The specimens were cemented to 1-mm-thick lithium disilicate ceramic plates with different cement film thicknesses (100 and 300 µm) using metal strips as spacers. The cements used were etch-and-rinse (RelyX Ultimate) and self-adhesive (RelyX U200) resin cements. Compressive load was applied on the ceramic plates using a universal testing machine, and fracture loads were recorded in Newtons (N). Statistical analysis was performed by multiple regression (p < 0.05). Representative specimens were evaluated by scanning electron microscopy to control the cement film thickness. RESULTS: The RelyX Ultimate group with a cement thickness of 100 µm cemented to enamel showed the highest mean fracture load (MFL; 1591 ± 172.59 N). The RelyX Ultimate groups MFLs were significantly higher than the corresponding RelyX U200 groups (p < 0.05), and thinner film cement demonstrated a higher MFL than thicker films (p < 0.05). Bonding to dentin resulted in lower MFL than with enamel (p < 0.001). CONCLUSIONS: Higher fracture loads were related to thinner cement film thickness and RelyX Ultimate resin cement. Bonding to dentin resulted in lower fracture loads than bonding to enamel. CLINICAL SIGNIFICANCE: Reduced resin film thickness could reduce lithium disilicate restoration fracture. Etch-and-rinse resin cements are recommended for cementing on either enamel or dentin, compared with self-adhesive resin cement, for improved fracture resistance.

Wear properties of lithium disilicate glass-ceramic and bovine tooth enamel:An in vitro study / 实用口腔医学杂志

Objective:To investigate the wear characteristics of bovine enamel and lithium disilicate glass ceramic under simulated oral environment.Methods:18 cylindrical lithium disilicate glass-ceramic specimens with the length of 8 mm and diameter of 3 mm were randomly divided into 2 groups (n =9),9 lithium disilicate glass-ceramic specimens and 9 bovine enamel specimens were served as the antagonists respectively.The specimens were then loaded in a wear simulator and subjected to friction force of 10 N for 540 000 cycles in artificial saliva and room temperature(speed 100 r/min,turning radius of 2.5 mm,uniform circular motion) condition.During the testing,10 checkpoints were applied to measure the height loss of the specimens with 3D profilometer,then wear curves were plotted.Scanning electron microscopy were applied to investigate the worn surfaces at different wear stages.Results:At every checkpoints,bovine enamel wear height loss was larger than the lithium disilicate specimens (P ＜ 0.05);bovine enamel wear curve exhibits a runningin period,steady wear period and severe wear period 3 stages of wear,while wear curves of lithium disilicate glass ceramics exhibit onlyrunning-in period and steady wear period 2 wear stages.Both groups had the corresponding micro-morphological features in different periods.Conclusion:Bovine enamel and lithium disilicate glass ceramics show a phase dynamic evolution law under the simulated oral environment.Bovine enamel is more susceptible to wear than lithium disilicate,suggesting that clinical attention should be paid to prevent the excessive wear of natural teeth caused by lithium disilicate glass ceramic restorations.

Impact of digital impression techniques on the adaption of ceramic partial crowns in vitro.

OBJECTIVES: To investigate the effects, digital impression procedures can have on the three-dimensional fit of ceramic partial crowns in vitro. METHODS: An acrylic model of a mandibular first molar was prepared to receive a partial coverage all-ceramic crown (mesio-occlusal-distal inlay preparation with reduction of all cusps and rounded shoulder finish line of buccal wall). Digital impressions were taken using iTero (ITE), cara TRIOS (TRI), CEREC AC with Bluecam (CBC), and Lava COS (COS) systems, before restorations were designed and machined from lithium disilicate blanks. Both the preparation and the restorations were digitised using an optical reference-scanner. Data were entered into quality inspection software, which superimposed the records (best-fit-algorithm), calculated fit-discrepancies for every pixel, and colour-coded the results to aid visualisation. Furthermore, mean quadratic deviations (RMS) were computed and analysed statistically with a one-way ANOVA. Scheffé's procedure was applied for multiple comparisons (n=5, α=0.05). RESULTS: Mean marginal (internal) discrepancies were: ITE 90 (92) µm, TRI 128 (106) µm, CBC 146 (84) µm, and COS 109 (93) µm. Differences among impression systems were statistically significant at p<0.001 (p=0.039). Qualitatively, partial crowns were undersized especially around cusp tips or the occluso-approximal isthmus. By contrast, potential high-spots could be detected along the preparation finishline and at central occlusal boxes. CONCLUSIONS: Marginal and internal fit of milled lithium disilicate partial crowns depended on the employed digital impression technique. CLINICAL SIGNIFICANCE: The investigated digital impression procedures demonstrated significant fit discrepancies. However, all fabricated restorations showed acceptable marginal and internal gap sizes, when considering clinically relevant thresholds reported in the literature.

Sucesso previsível como resultado do trabalho em equipe: reabilitação oral complexa usando cerâmica pura: parte 2 / Predictable success as a result of teamwork: complex full-mouth rehabilitation using all-ceramics: part 2

A escolha dos materiais e dos passos do tratamento exigidos somente deverá ser iniciada quando as metas finais do tratamento estiverem totalmente definidas. Desse modo, será possível obter-se sincronização entre eles, para possibilitar resultado com sucesso. Nesta segunda parte do artigo, os autores mostram um modo sistemático para a confecção de reabilitações orais em casos complexos. A primeira parte deste artigo tratou do eficiente planejamento e da seleção de materiais cerâmicos apropriados, esta segunda parte é dedicada aos procedimentos da fabricação e incorporação de restaurações extensas.

Only if the treatment goals have been well defined before the treatment is started may the range of materials and the required treatment steps be synchronized with each other and streamlined towards a successful outcome. In this two-part article Prof. Dr Daniel Edelhoff and Oliver Brix present a systematic way to the full-mouth rehabilitation of complex cases. The first part deals with the efficient planning and targeted selection of appropriate ceramic materials. This part is dedicated to the fabrication and incorporation of extensive restorations.

Sucesso previsível como resultado do trabalho em equipe: reabilitação oral complexa usando cerâmica pura: parte 1 / Predictable success as a result of teamwork: complex full-mouth rehabilitation using all-ceramics: part 1

A infinidade de materiais e as etapas de tratamento necessárias poderão ser sincronizadas e eficientes, no sentido de um desfecho de sucesso, somente se os objetivos do tratamento forem definidos antes de seu início. Neste artigo de duas partes, os autores apresentam um modo sistemático para a confecção de reabilitações orais em casos complexos. A primeira parte do artigo trata do eficiente planejamento e da seleção de materiais cerâmicos apropriados...

Only if the treatment goals have been well defined before the treatment is started may the range of materials and the required treatment steps be synchronized with each other and streamlined towards a successful outcome. In this two-part article Prof. Dr Daniel Edelhoff and Oliver Brix present a systematic way to the full-mouth rehabilitation of complex cases. The first part deals with the efficient planning and targeted selection of appropriate ceramic materials...