Effect of different surface modifications on the bonding of a soft liner to a denture base material

Amaç: Çalışmanın amacı, polidimetilsiloksan protez astarının farklı boyutlardaki alüminyum oksit parçacıkları ile kumlanmış olan protez kaide maddesine gerilme bağlanma mukavemetini araştırmaktır. Gereç Yöntemler:  Kırk adet iki parçadan dikdörtgen prizma şeklinde ısı ile polimerize edilmiş akrilik örnekler bağlantı dayanımıiçin değerlendirilecektir. Örnekler uygulanan yüzey işlemine göre 4 test grubuna ayrılmıştır. Grup I: Yüzey işlemi uygulanmayan (kontrol grubu) Grup II: Kumlama ile birlikte tribokimyasal silika kaplama Grup III: 50 μm alüminyum oksit partikülleri ile kumlama Grup IV: 110 μm alüminyum oksit partikülleri ile kumlama.  Bütün örnekler yumuşak astar ile bağlantı sağlandıktan sonra 5000 devir termal siklusa tabi tutulmuştur. Bağlantı değeri, evrensel test cihazı kullanılarak çekme test ile belirlenmiştir.  Verilerin normalliği Shapiro-Wilk testi ile test edildi. Tüm veriler tek yönlü ANOVA kullanılarak analiz edildi ve ortalama değerleri Tukey’in HSD testi ile karşılaştırıldı. (p <0.05). Bulgular: En yüksek bağ mukavemet değeri Grup II'de (1.51 ± 0.41 MPa) gözlendi. En düşük değer, yüzey işlemi uygulanmayan örneklerin bulunduğu grupta gözlendi (0.85 ± 0.27 MPa). Grup I, grup II ve grup III'den anlamlı olarak farklıydı (p <0.05) Sonuç: Akrilik yüzeylerin 30 μm silika kaplı alüminyum oksit partikülleri ile kumlama işlemine tabi tutulması, bağlanma mukavemetini artırdı.Anahtar Kelimeler:  çekme dayanımı, polimetilmetakrilat, yumuşak astar, yüzey özellikler

Antibakterijsko i antifungalno djelovanje klorheksidin-diacetata ugrađenog u akrilatne smole koje se upotrebljavaju za privremene nadomjestke

Objective: The surface of provisional restorations applied before conventional or implant- supported fixed restorations may cause bacterial or fungal biofilm formation. The aim of this study was to evaluate the antimicrobial activity of acrylic resins used in provisional restorations modified with chlorhexidine diacetate. Methods: 120 cylindrical, auto-polymerized resin samples modified with chlorhexidine diacetate were prepared at concentrations of 0 (control), 1, 3, 5 wt %. The antimicrobial activity was examined against Streptococcus mutans, Enterococcus faecalis, and Candida albicans using Crystal Violet quantification, MTT assay, and Scanning Electron Microscopy. Data were analyzed by ANOVA and paired sample t-tests (α=0.05). Results: The addition of chlorhexidine diacetate influenced the growth rate and metabolic activity of microorganisms. The antimicrobial effect against C. albicans and S. mutans statistically increased with the percentage of chlorhexidine diacetate. E. faecalis bacteria were less affected by chlorhexidine diacetate compared to other pathogens. Conclusion: It has been shown that the effectiveness of CHDA in inhibiting the proliferation of microorganisms correlated positively with increasing concentration levels. More research is needed to confirm the impact of different chlorhexidine concentrations on the mechanical properties, clinical efficacy, and antimicrobial properties of CDHA.Svrha istraživanja: Površina privremenih nadomjestaka koji se koriste prije trajnih fiksnih nadomjestaka ili nadomjestaka postavljenih na implantate može prouzročiti stvaranje bakterijskoga ili gljivičnoga biofilma. Cilj ovog istraživanja bio je procijeniti antimikrobno djelovanje akrilatnih smola koje se upotrebljavaju u privremenim restauracijama modificiranima klorheksidin-diacetatom. Materijal i metode: Pripremljeno je 120 cilindričnih, autopolimeriziranih uzoraka smole modificirane klorheksidin-diacetatom u koncentracijama od 0 (kontrola), 1, 3, 5 težinskih postotaka. Antimikrobna aktinost ispitivana je za mikroorganizme Streptococcus mutans, Enterococcus faecalis i Candida albicans kvantifikacijom Crystal Violeta, MTT testom i skenirajućom elektronskom mikroskopijom. Podatci su analizirani ANOVA-om i t-testom uparenih uzoraka (α = 0,05). Rezultati: Dodatak klorheksidin-dia-cetata utjecao je na brzinu rasta i metaboličku aktivnost mikroorganizama. Antimikrobni učinak kad je riječ o C. albicans i S. mutans statistički se povećavao s postotkom klorheksidin-diacetata. Bakterija E. faecalis bila je manje pogođena klorheksidin-diacetatom u usporedbi s drugim patogenima. Zaključak: Pokazalo se da učinkovitost CHDA-e u inhibiciji proliferacije mikroorganizama pozitivno korelira s povećanjem razine koncentracije. Potrebna su dodatna istraživanja kako bi se utvrdio utjecaj različitih koncentracija klorheksidina na mehanička svojstva, kliničku učinkovitost i antimikrobna svojstva CDHA-e

Trueness of crowns fabricated by using additively and subtractively manufactured resin-based CAD-CAM materials.

STATEMENT OF PROBLEM Advancements in digital dental technologies have enabled the use of different resin-based materials that can be fabricated either additively or subtractively. However, knowledge on the fabrication trueness of these materials is scarce. PURPOSE The purpose of this in vitro study was to investigate the trueness of crowns fabricated by using different resin-based computer-aided design and computer-aided manufacturing (CAD-CAM) materials. MATERIAL AND METHODS A complete crown for a mandibular right first molar with a 30-μm cement space was designed in standard tessellation language (STL) format. This master STL (MC-STL) was used to fabricate 40 complete crowns with 4 different resin-based CAD-CAM materials and either additive (Crowntec [MS]) or subtractive techniques (Brilliant Crios [BC], breCAM.monoCOM [PMMA], and G-CAM [GR]; n=10). All crowns were digitized with an intraoral scanner (CEREC Primescan SW 5.2) to generate their STL files (TC-STLs). MC-STL and TC-STLs were transferred into a 3-dimensional analysis software program (Medit Link v2.4.4), and a trueness (overall, external, occlusal, intaglio occlusal, and marginal) analysis was performed by using the root mean square (RMS) method. The Kruskal-Wallis and Dunn tests were performed to analyze data (α=.05). RESULTS The test groups had significantly different deviations on all surfaces (P≤.001). MS crowns had higher overall (P≤.007) and external surface (P≤.001) deviations than GR and PMMA crowns, while the differences between GR and PMMA crowns were not significant (P≥.441). BC crowns had higher external surface deviations than GR crowns (P=.005), higher occlusal deviations than GR and MS crowns (P≤.007), and higher intaglio occlusal deviations than GR and MS crowns (P≤.009). However, BC crowns had lower marginal deviations than MS and GR crowns (P≤.018). CONCLUSIONS The brand of resin-based CAD-CAM materials affected the trueness of crowns. Additively manufactured crowns (MS) mostly had lower overall and external surface trueness than the other groups. Nevertheless, the deviation values of occlusal, intaglio occlusal, and marginal trueness were generally small; thus, the effect of the tested materials on clinical crown fit may be negligible

Effect of simulated brushing and disinfection on the surface roughness and color stability of CAD-CAM denture base materials.

PURPOSE To evaluate the effect of simulated brushing and chemical disinfection on the surface roughness and color stability of CAD-CAM denture base materials and to compare with those of a heat-cured denture base material. MATERIAL AND METHODS Disk-shaped specimens (Ø 10mm × 2 mm) were prepared from 3 CAD-CAM denture base resins (AvaDent, Ava; Merz M-PM, Merz; Polident d.o.o, Poli) and a heat-cured polymethylmethacrylate resin (Promolux, Conv) (n = 30). After polishing, baseline surface roughness (Ra) and color coordinates were measured. The measurements were repeated after 20000 cycles of simulated brushing, and the specimens were divided into 3 groups according to disinfection protocol (distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet) (n = 10). After 9 cleaning cycles over a period of 20 days, Ra and color coordinates were remeasured. Color differences (ΔE00) were calculated by using CIEDE2000 formula. One-way analysis of variance (ANOVA) and pairwise t-tests were used to analyze Ra and ΔE00 data, while repeated measures ANOVA test was used to compare baseline, after brush, and after disinfection Ra values (α = 0.05). RESULTS Brushing did not affect the Ra values of tested materials (P ≥ .08). Both before and after brushing, Merz and Conv had higher Ra values than Poli and Ava (P < .001). Among disinfectants, effervescent tablet led to the lowest Ra for Merz (P = .003) and the highest Ra for Poli (P ≤ .039). Only NaOCl resulted in significant differences among the Ra of materials (P < .001), as Merz and Conv had higher Ra values than Poli (P ≤ .002). Repeated measures ANOVA revealed that effervescent tablet disinfection of Merz led to lower Ra values than those of baseline and after brushing (P ≤ .042). After brushing, Ava and Conv had higher ΔE00 values compared with Merz and Poli (P ≤ .015). When compared with other disinfection protocols, effervescent tablet led to higher ΔE00 values for Merz and Poli (P < .001). Significant differences were observed among materials when NaOCl was used; Conv had higher ΔE00 values than Ava and Merz (P = .004). CONCLUSIONS Brushing did not increase the surface roughness of materials. Disinfection protocol's effect on the surface roughness varied. The effect of brushing on the color of materials varied; color of Ava and Conv was affected from brushing more than the other materials. Color stability of materials varied depending on the disinfection protocol. Effervescent tablet caused higher color change with Merz and Poli compared with other disinfectants. NaOCl led to small color change for Poli, Ava, and Merz materials

Surface Roughness and Color Stability of 3D-Printed Denture Base Materials after Simulated Brushing and Thermocycling.

Three-dimensional (3D) printing is increasingly used to fabricate denture base materials. However, information on the effect of simulated brushing and thermocycling on the surface roughness and color stability of 3D-printed denture base materials is lacking. The aim of this study was to evaluate the effect of brushing and thermocycling on the surface roughness and color stability of 3D-printed denture base materials and to compare with those of milled and heat-polymerized denture base resins. Disk-shaped specimens (Ø 10 mm × 2 mm) were prepared from 4 different denture base resins (NextDent Denture 3D+ (ND); Denturetec (SC); Polident d.o.o (PD); Promolux (CNV)) (n = 10). Surface roughness (Ra) values were measured before and after polishing with a profilometer. Initial color coordinates were measured by using a spectrophotometer after polishing. Specimens were then consecutively subjected to simulated brushing (10,000 cycles), thermocycling (10,000 cycles), and brushing (10,000 cycles) again. Ra and color coordinates were measured after each interval. Color differences (ΔE00) between each interval were calculated and these values were further evaluated considering previously reported perceptibility (1.72 units) and acceptability (4.08 units) thresholds. Data were analyzed with Friedman, Kruskal-Wallis, and Mann-Whitney U tests (α = 0.05). Ra (p ≥ 0.051) and ΔE00 (p ≥ 0.061) values among different time intervals within each material were similar. Within each time interval, significant differences in Ra (p ≤ 0.002) and ΔE00 values (p ≤ 0.001) were observed among materials. Polishing, brushing, and thermocycling resulted in acceptable surface roughness for all materials that were either similar to or below 0.2 µm. Color of ND printed resin was affected by brushing and thermocycling. All materials had acceptable color stability when reported thresholds are considered

Effect of measurement techniques and operators on measured deviations in digital implant scans.

OBJECTIVES To evaluate the effect of different measurement techniques and operators on measured deviations in in vitro implant scans. METHODS A 2-piece system that comprises a healing abutment (HA) and a scan body (SB) was mounted onto an implant at right first molar site of a polymethylmethacrylate mandibular dentate model. Model was digitized by using an industrial scanner (reference model scan, n=1) and an intraoral scanner (test scan, n=20). All standard tessellation language files were imported into a 3-dimensional analysis software and superimposed. Three operators with similar experience performed circle-based and point-based deviation analyses (n=20). Deviations measured with different techniques were compared with paired samples t-test within each operator, while the reliability of the operators was assessed by using F-tests for both technqiues (α=.05). RESULTS Point-based technique resulted in lower deviations than circle-based technique for all operators (P=.001) with to higher reliability among operators (ICC=.438, P=.001). The correlation among the operators was nonsignificant when circle-based technique was used (ICC=.114, P=.189). CONCLUSION Lower deviations were detected with the point-based technique. In addition, different operators' measurements had higher correlation when point-based technique was used compared with circle-based technique. CLINICAL SIGNIFICANCE Point-based technique may be preferred over circle-based technique for research studies on scan accuracy of implants, given its higher reliability. The accuracy of measured deviations may increase if the number of planes are increased, which can facilitate point generation at different surfaces of the scan body

Effect of Potassium Aluminum Sulfate Application on the Viability of Fibroblasts on a CAD-CAM Feldspathic Ceramic before and after Thermocycling.

Potassium aluminum sulfate (alum) is a known adjuvant, which has been used as a mordant in textile industry for color fixation. This material has potential to be incorporated into dentistry for color stability, yet its toxicity first needs to be evaluated. The present study aimed to evaluate the cytotoxic potential of potassium aluminum sulfate (alum) on fibroblasts when applied onto feldspathic ceramic before and after thermocycling. Forty-eight feldspathic ceramic specimens were divided into four groups (FC: no alum application or thermocycling; FCT: thermocycling without alum application; FA: alum application without thermocycling; FAT: alum application and thermocycling) (n = 12). Cell viability was assessed by using a tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphnyltetrazolium bromide assay at 24 and 72 h, and cell cultures without any ceramic specimens served as control (C). One sample from each material group was further analyzed with energy dispersive X-ray spectroscopy (EDX). Cell viability at different time intervals within each group was analyzed with Friedman tests, while Kruskal-Wallis tests were used to compare the test groups within each time interval. Pairwise comparisons were further resolved by using Wilcoxon tests (a = 0.05). C had lower (p = 0.01) and FA had higher (p = 0.019) cell viability after 72 h. After 24 h, the highest cell viability was observed in C (p ≤ 0.036). After 72 h, the differences between C and FA, C and FAT, FC and FA, and FCT and FAT were nonsignificant (p &gt; 0.05). Cell viability was not affected by alum application or thermocycling at any time interval (p ≥ 0.631). EDX analysis showed an increase in potassium concentration in FA and FAT when compared with FC and FCT. Regardless of the time interval, alum application onto feldspathic ceramic and thermocycling did not influence the cell viability

Surface roughness, optical properties, and microhardness of additively and subtractively manufactured CAD-CAM materials after brushing and coffee thermal cycling.

PURPOSE To evaluate the surface roughness, optical properties, and microhardness of additively or subtractively manufactured CAD-CAM materials after simulated brushing and coffee thermal cycling. MATERIAL AND METHODS Two additively manufactured resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and 3 subtractively manufactured materials (a reinforced composite (Brilliant Crios, BC), a polymer-infiltrated ceramic network (Enamic, VE), and a feldspathic ceramic (Mark II, VM)) were used to fabricate disk-shaped specimens (Ø10×1-mm) (n = 10). Surface roughness, Vickers microhardness, and color coordinates were measured after polishing, while surface roughness was also measured before polishing. Specimens were then subjected to 25000 cycles of brushing and 10000 cycles of coffee thermal cycling, and measurements were repeated after each time interval. Color difference (ΔE00 ) and relative translucency parameter (RTP) were calculated. Robust analysis of variance test was used to evaluate surface roughness, ΔE00 , and RTP data, while generalized linear model analysis was used for microhardness data (α = .05). RESULTS Material type and time interval interaction affected tested parameters (P≤.002). In addition, material type affected all parameters (P<.001) other than surface roughness (P = .051), and time interval affected surface roughness and microhardness values (P<.001). Tested materials mostly had their highest surface roughness before polishing (P≤.026); however, there was no clear trend regarding the roughness of materials within different time intervals along with ΔE00 and RTP values within materials or time intervals. VS and CT had the lowest microhardness regardless of the time interval, while the remaining materials were listed as VM, VE, and BC in decreasing order (P<.001). Coffee thermal cycling only reduced the microhardness of VM (P<.001). CONCLUSIONS Tested additively manufactured resins can be considered more susceptible to simulated brushing and coffee thermal cycling than the other materials, given the fact that their surface roughness and ΔE00 values were higher than previously reported acceptability thresholds and because they had the lowest microhardness after all procedures were complete. This article is protected by copyright. All rights reserved