Enamel wear against monolithic zirconia restorations: A meta-analysis and systematic review of in vitro studies.

OBJECTIVE: An assessment was performed to identify and evaluate dental enamel wear caused by monolithic zirconia restoration. Literature searches were conducted in PubMed, Science Direct, Cochrane Evidence, and the Cochrane Library up to May 2020. MATERIAL AND METHODS: Studies were selected for systematic review according to the inclusion (articles conducted on the wear of enamel samples opposing monolithic zirconia) and exclusion (case reports, non-English articles, and monolithic zirconia samples facing other materials rather than human enamel) criteria. Of those, articles on polished and glazed monolithic zirconia subjected to a 50 N vertical load with a range of 240,000-250,000 cycles, equivalent to 1 year of in vivo mastication, were included in the meta-analysis. RESULTS: In total, 3968 articles were pooled. Twenty-five articles met the inclusion criteria for the systematic review. Three studies were included in the meta-analysis. The results showed that the enamel wear against monolithic zirconia was within the statistically accepted level. Moreover, the polished monolithic zirconia surface caused less enamel wear than the glazed surface. CONCLUSION: This review indicates that monolithic zirconia restorations cause acceptable antagonist enamel wear. Moreover, the meta-analysis results agreed that the final restoration's surface texture plays an essential role in the wear process. CLINICAL SIGNIFICANCE: Monolithic zirconia restorations have been widely used in dental practice because they eliminate the chipping problems resulting from using veneered restorations. With recent technology development, monolithic zirconia has obtained more esthetic features and a more natural look. However, due to the high strength and surface roughness of monolithic zirconia, wear on the antagonist's teeth was detected. The results showed that this wear amount was statistically acceptable and lower than other ceramics such as feldspathic porcelain and enamel. Furthermore, surface treatment methods must be applied to minimize tooth wear, as polished or glazed surfaces interfere with enamel loss.

Cleaning Efficacy of Poly-ether-ether-ketone Tips in Eliminating Cement Remnants Around Implants With Different Abutment Heights.

The excess cement not removed after the cementation of fixed implant-supported restorations may cause loss of peri-implant attachment or adjacent bone. The aims of this study were to evaluate the amount of residual cement at different abutment-crown connection levels and to test the cleaning efficacy of poly-ether-ether-ketone (PEEK) ultrasonic tips after cementation. One implant was placed in an anterior central tooth position 5 mm below the gingival margin in an acrylic model, and 32 stone models were obtained with implant analogs. Abutment heights of 1-2 and 2.5-4 mm were used on the vestibular and lingual sides, respectively. Crowns were cemented and cleaned, and half of the samples were cleaned again using PEEK tips. The abutment-crown suprastructure was then disconnected, and cleaning efficacy was evaluated. Varying amounts of excess cement were found on all specimens except for the PEEK group with abutment-crown connections 1 mm below the gingival margin. An increase of undetected cement remnants was observed when the restoration margins were located deeper subgingivally. Various amounts of excess cement associated with margin location were detected on the abutment-restoration complex despite meticulous cleaning efforts. Ultrasonic PEEK tips were effective at cleaning the cement remnants around implants to a certain depth.

Efficacy of Diode Laser and Gluma on Post-Preparation Sensitivity: A Randomized Split-Mouth Clinical Study.

OBJECTIVE: This study aimed to compare the efficacy of a 940-nm diode laser and Gluma desensitizer on post-preparation sensitivity of prepared teeth. MATERIALS AND METHODS: Twenty patients with 76 teeth participated in the study. For each patient, prepared molar or premolar in one quadrant were individually irradiated by laser. In the symmetrical quadrant, Gluma was applied onto the prepared teeth. No treatment was performed in the control group. Temporary crowns were placed after preparation. Pain response to tactile stimulus was assessed at one day, one week, and two weeks using visual analog scale (VAS). Intergroup comparisons were made with Kruskal Wallis test (p < 0.05). RESULTS: Mean VAS scores of the control group were statistically higher than laser and Gluma groups (p < 0.017). The difference between VAS scores of the laser and Gluma groups was statistically insignificant (p > 0.05). CONCLUSIONS: A significant reduction in level of sensitivity after both treatments was observed. The reduction of sensitivity with Gluma was not significantly superior to laser. No significant additional reduction occurred in level of sensitivity from the first day to the second week after both treatments. CLINICAL SIGNIFICANCE: The application of Gluma or a 940-nm diode laser may be considered as effective in reducing sensitivity after tooth preparation without superiority of either method. (J Esthet Restor Dent 28:405-411, 2016).

Effect of Opaque Layer Application on the Color of Resin Composites Used to Fill Access Openings of Screw-Retained Implant Restorations.

The purpose of this preliminary in vitro study was to evaluate the effect of an opaque layer and application of resin composite in dual colors on the ΔE values of resin composites used to fill access openings of screw-retained implant restorations. Sixty cylindrical nickel-chromium metal molds with a central channel simulating a posterior screw-retained, implant-supported, porcelain-fused-to-metal crown were cast. Access openings were filled with combinations of opaquer, enamel composite (A2E), dentin composite (A2B and A3B), and resilient composite. ΔE values differed significantly among the groups (P<.01). The combination of opaque layer and dual color resin composites of shades A2E and A3B resulted in significantly lower ΔE values than the other groups (P<.01).

Effects of various denture cleansers on surface roughness of hard permanent reline resins.

The aim of this study was to investigate the influence of denture cleansers on surface roughness (Ra, µm) of two hard permanent reline resins and a conventional acrylic denture base resin. Fifty specimens of each material, measuring 10 mm×2 mm were randomly divided into 1 control and 4 experimental subgroups (n=10). Surface roughness values were measured using profilometer before and after immersion in distilled water and in 4 different denture cleansers for 8 h for 140 days. The Kruskal Wallis and Wilcoxon Signed Ranks tests were used for comparison among groups with a significance level of α=0.05. Immersion in denture cleansers significantly increased the surface roughness of reline resins and the difference among the cleansers was statistically significant (p=0.059). Denture cleansers can cause significant surface roughness alterations on hard permanent reline resins and denture base resin where their effect may differ according to the selected resin material.

Effect of various lasers on the bond strength of two zirconia ceramics.

OBJECTIVE: The purpose of this study was to compare and evaluate the effects of various laser systems on surface roughness and shear bond strengths of zirconia ceramics. MATERIAL AND METHODS: Seventy-two ceramic discs (10 mm×2 mm) obtained from two sintered zirconia ceramics (Zirkonzahn, Zirkonzahn Prettau(®)) were divided into two groups (n=36) according to the computer-aided design (CAD)-computer-aided manufacturing (CAM) technique and then further divided into three groups (n=12). Each group was treated with one of the following: (1) femtosecond (FS), (2) Nd:YAG (NY), and (3) Er:YAG (EY) lasers. After laser irradiation, a scanning electron micrograph (SEM) was taken at 500× magnification for qualitative examination. Following surface roughness measurement by profilometry, resin cement (Rely X U200) was bonded to the ceramic specimens using Teflon tubes (3 mm height, 4 mm diameter). Specimens were stored in distilled water at 37°C for 24 h and then thermal cycled for 5000 cycles. A shear bond strength (MPa) test was performed using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed by two way analysis of variance (ANOVA) and Tukey honest significant difference (HSD) tests for pairwise comparisons among groups (p=0.05). RESULTS: MPa and roughness were significantly affected by laser type (p<0.001), and there was no significant interaction between the two zircon ceramics. The group irradiated with FS laser had significantly higher (p<0.05) roughness and MPa mean values than those of the other groups. No significant difference was found between the groups irradiated with NY and EY laser (p>0.05). In the SEM, the surfaces of the FS group were rougher than those of the NY and EY groups. NY and EY surfaces were nearly smooth. CONCLUSIONS: FS laser is an effective surface treatment for roughening surfaces of zirconia ceramics. Furthermore, it reveals the highest MPa.

Effect of liquid polishing materials on the stainability of bis-acryl interim restorative material in vitro.

STATEMENT OF PROBLEM: The discoloration of interim restorations may negatively affect a patient's perception of treatment. PURPOSE: The purpose of this study was to investigate the effect of liquid polishing materials on the color stability of bis-acryl interim restorative material. MATERIAL AND METHODS: One hundred twenty specimens (10×2 mm) of a bis-acryl interim restorative material were divided into 3 groups. Group CO (control) was not subjected to any liquid polishing material. Groups GC and BC were polished with 2 liquid polishing materials. The specimens were then divided into 4 subgroups (n=10) and stored for 24 hours at 37°C in different staining solutions: coffee, coffee with sugar, cola, and distilled water. The color of the specimens was measured at baseline and after immersion with a spectrophotometer by using the CIE L*a*b* system, and color changes (ΔE) were calculated. The means of color change for each specimen were analyzed by 2-way and 1-way ANOVA tests. Post hoc comparisons were made with the Tukey HSD and Tamhane T2 tests. RESULTS: The application of liquid polishing materials significantly decreased the staining of autopolymerized bis-acryl interim restorative material (P<.01). Coffee with sugar resulted in higher ΔE values than coffee without sugar or cola. CONCLUSIONS: The use of liquid polishing materials significantly decreased staining when compared with bis-acryl specimens without liquid polish. The presence of sugar in coffee increased color change compared with coffee without sugar for all groups evaluated.

Effects of different surface treatments on shear bond strength in two different ceramic systems.

The purpose of this study was to evaluate the influence of different surface treatments (sandblasting, acid etching, and laser irradiation) on the shear bond strength of lithium disilicate-based core (IPS Empress 2) and feldspathic ceramics (VITA VM 9). One hundred ceramic discs were divided into two groups of 50 discs each for two ceramic systems: IPS Empress 2 (group I) and VITA VM 9 (group II). Each of the two groups was further divided into five surface treatment groups (ten each) as follows: group SB, sandblasting with alumina particles (50 µm); group HF, 5 % hydrofluoric acid etching; group L, Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10 W; manually, noncontact R14 handpiece); group SB-L, sandblasting + Er:YAG laser; and group HF-L, 5 % hydrofluoric acid + Er:YAG laser. Luting cement (Panavia 2.0) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, a shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with a two-way analysis of variance (ANOVA) and Tukey's honestly significant difference tests (α = 0.05). The two-way ANOVA indicated that the shear bond strength was significantly affected by the surface treatment methods (p < 0.05), but there was no significant interaction between the ceramic systems. Group SB-L had the highest mean values for each ceramic system. Sandblasting, followed by Er:YAG laser irradiation, enhanced the bond strength, indicating its potential use as an alternative method. The atomic force microscopic evaluation revealed that group SB had the most distinct sharp peaks among the groups.

Comparison of the effects of surface treatments on roughness of two ceramic systems.

OBJECTIVE: The aim of this study was to evaluate the effects of different surface treatments on the surface roughness of lithium disilicate-based core (IPS Empress 2, shade 210, Ivoclar Vivadent, Schaan, Liechtenstein) and feldspathic ceramics (Vita VM9, VITA Zahnfabrik H. Rauter GmbH & Co. KG, Bad Säckingen, Germany). BACKGROUND DATA: Er:YAG laser irradiation is expected to be an alternative surface treatment, thus enhances surface roughness of procelains and produces morphological changes. METHODS: Fifty lithium disilicate-based core ceramic discs and 50 feldspathic ceramic discs were prepared (diameter, 10 mm; thickness, 1 mm) according to the manufacturers' instructions. All-ceramic discs were polished to standardize, and surface roughness of the discs was evaluated before treatment and serving as controls. Both of two ceramic groups were divided into five groups (n=10), and the following treatments were applied: (1) sandblasting with aluminum oxide (Al(2)O(3); Group SB); (2) Al(2)O(3)+Er:YAG laser (Group SB-L); (3) Er:YAG laser irradiation (distance, 1 mm; 500 mJ; 20 Hz; 10W; manually, contact handpiece [R 14]) (Group L); (4) 5% hydrofluoric acid etching (Group HF); and (5) Er:YAG laser +5% hydrofluoric acid (Group HF-L). Surface roughness was evaluated by profilometry, and specimens were then examined with atomic force microscopy. RESULTS: Data were analyzed by Wilcoxon signed rank, Mann-Whitney U, and Kruskal-Wallis tests (α=0.05). The Wilcoxon signed rank test results indicated that surface roughness after sandblasting was significantly different from the surface roughness after laser irradiation and acid etching (p<0.001). Mann-Whitney U and Kruskal-Wallis test results indicated that groups SB and SB-L had significantly higher mean roughness values (p<0.05) than those in the other groups. CONCLUSIONS: Groups SB and SB-L had rougher surfaces than the groups subjected to the other surface treatment methods. There was no significant difference in surface roughness between the HF acid etching, Er:YAG laser irradiation, and HF and Er:YAG (p<0 .05).

Single tooth replacement using a ceramic resin bonded fixed partial denture: A case report.

This article describes the use of an all ceramic resin-bonded fixed partial denture as a conservative solution for the replacement of an incisor. It is a minimally invasive technique that does not discolor the abutment teeth.

Effect of different surface treatments on roughness of IPS Empress 2 ceramic.

The aim of this study was to evaluate the influence of different surface treatments (air abrasion, acid etching, laser irradiation) on the surface roughness of a lithium-disilicate-based core ceramic. A total of 40 discs of lithium disilicate-based core ceramic (IPS Empress 2; Ivoclar Vivadent, Schaan, Liechtenstein) were prepared (10 mm in diameter and 1 mm in thickness) according to the manufacturer's instructions. Specimens were divided into four groups (n = 10), and the following treatments were applied: air abrasion with alumina particles (50 µm), acid etching with 5% hydrofluoric acid, Nd:YAG laser irradiation (1 mm distance, 100 mJ, 20 Hz, 2 W) and Er:YAG laser irradiation (1 mm distance, 500 mJ, 20 Hz, 10 W). Following determination of surface roughness (R(a)) by profilometry, specimens were examined with atomic force microscopy. The data were analysed by one-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). One-way ANOVA indicated that surface roughness following air abrasion was significantly different from the surface roughness following laser irradiation and acid etching (P < 0.001). The Tukey HSD test indicated that the air abrasion group had a significantly higher mean value of roughness (P < 0.05) than the other groups. No significant difference was found between the acid etching and laser irradiation (both Er:YAG and Nd:YAG) groups (P > 0.05). Air abrasion increased surface roughness of lithium disilicate-based core ceramic surfaces more effectively than acid-etching and laser irradiation.

The effect of different surface treatments on roughness and bond strength in low fusing ceramics.

The aim of this study was to evaluate the influence of different surface treatments (air abrasion, acid etching, and laser irradiation) on the surface roughness and bond strength of a low fusing ceramic. Thirty-six discs of low fusing ceramic (Finesse, Ceramco) were prepared (10 mm in diameter and 2 mm in thickness) according to the manufacturer's instructions. Specimens were divided into three groups (n = 12), and the following treatments were performed: Air abrasion with alumina particles (50 µm), acid etching with 5% HF and Nd:YAG laser irradiation (distance: 1 mm, 100 mJ, 20 Hz, 2 W, and 141.54 J/cm(2)). Following determination of surface roughness (R(a)) by profilometry, specimens were examined with scanning electron microscopy (SEM). The luting cement (Clearfil Esthetic Cement) was bonded to the ceramic specimens using Teflon tubes. After 24 h of water storage, shear bond strength test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed with two-way analysis of variance (ANOVA) and Tukey HSD tests (α = .05). Two-way ANOVA indicated that surface roughness was significantly affected by surface treatments (p < .001). Tukey honestly significant difference (HSD) indicated that the air abrasion group had a significantly higher mean value (p < .05) than the other groups. Shear bond strength was significantly affected by surface treatments (p < .001). Tukey HSD indicated that the air abrasion group had a significantly higher mean value (p < .05) than the other groups. No significant difference was found between the acid-etching and laser-irradiation groups (p > .05). The SEM image of the laser irradiation surface appeared to be relatively smooth as compared to the images of other the groups. Air abrasion of low-fusing porcelain surfaces was effective in improving the bond strength as compared to the acid-etching and laser-irradiation methods.