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1.
Nadja Rohr Stefan Brunner Sabrina Märtin Jens Fischer 《The Journal of prosthetic dentistry》2018,119(1):138-145
Statement of problem
The best procedure for cementing a restoration to zirconia implants has not yet been established.Purpose
The purpose of this in vitro study was to measure the retention of polymer-infiltrated ceramic crowns to zirconia 1-piece implants using a wide range of cements. The effect of ceramic primer treatment on the retention force was also recorded. The retention results were correlated with the shear bond strength of the cement to zirconia and the indirect tensile strength of the cements to better understand the retention mechanism.Material and methods
The retention test was performed using 100 polymer-infiltrated ceramic crowns (Vita Enamic) and zirconia implants (ceramic.implant CI) The crowns were cemented with either interim cement (Harvard Implant semipermanent, Temp Bond), glass-ionomer cement (Ketac Cem), self-adhesive cement (Perma Cem 2.0, RelyX Unicem Automix 2, Panavia SA), or adhesive cement (Multilink Implant, Multilink Automix, Vita Adiva F-Cem, RelyX Ultimate, Panavia F 2.0, Panavia V5 or Panavia 21) (n=5). Additionally ceramic primer was applied on the intaglio crown surface and implant abutment before cementation for all adhesive cements (Multilink Implant, Multilink Automix: Monobond plus; RelyX Ultimate Scotchbond Universal; Vita Adiva F-Cem: Vita Adiva Zr-Prime; Panavia F2.0, Panavia V5: Clearfil Ceramic Primer) and 1 self-adhesive cement containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) (Panavia SA: Clearfil Ceramic Primer). Crown debond fracture patterns were recorded. Shear bond strength was determined for the respective cement groups to polished zirconia (n=6). The diametral tensile strength of the cements was measured (n=10). Statistical analysis was performed using 1-way or 2-way analysis of variance followed by the Fisher LSD test (α=.05) within each test parameter.Results
Adhesive and self-adhesive resin cements had shear bond strength values of 0.0 to 5.3 MPa and revealed similar retention forces. Cements containing MDP demonstrated shear bond strength values above 5.3 MPa and displayed increased retention. The highest retention values were recorded for Panavia F 2.0 (318 ±28 N) and Panavia 21 (605 ±82 N). All other adhesive and self-adhesive resin cements attained retention values between 222 ±16 N (Multilink Automix) and 270 ±26 N (Panavia SA), which were significantly higher (P<.05) than glass-ionomer (Ketac Cem: 196 ±34 N) or interim cement (Harvard Implant semipermanent: 43 ±6 N, Temp Bond: 127 ±13 N). Application of manufacturer-specific ceramic primer increased crown retention significantly only for Panavia SA.Conclusions
Products containing MDP provided a high chemical bond to zirconia. Self-adhesive and adhesive resin cements with low chemical bonding capabilities to zirconia provided retention force values within a small range (220 to 290 N). 相似文献2.
Krysta Sellers John M. Powers Sudarat Kiat-amnuay 《The Journal of prosthetic dentistry》2017,117(2):247-252
Statement of problem
The optimal retention of implant-supported ceramic crowns on zirconia abutments is a goal of prosthodontic treatment.Purpose
The purpose of this in vitro study was to evaluate the retentive strength of implant-supported IPS e.max CAD-CAM (e.max) crowns bonded to custom zirconia implant abutments with different cements.Material and methods
An optical scan of a zirconia custom abutment and a complete-coverage modified crown was designed using an intraoral E4D scanner. One hundred twenty lithium disilicate crowns (IPS e.max CAD) were cemented to 120 zirconia abutment replicas with 1 of 6 cements: Panavia 21 (P21), Multilink Hybrid Abutment (MHA), RelyX Unicem 2 (RXU), RelyX Luting Plus (RLP), Ketac Cem (KC), and Premier Implant (PI). The specimens were stored at 37°C in 100% humidity for 24 hours. Half of the specimens were thermocycled for 500 cycles. The retentive force was measured using a pull-out test with a universal testing machine. Mean retentive strengths (MRS) were calculated using 2-way ANOVA and the Tukey-Kramer test (α=.05).Results
The MRS (MPa) after 24-hour storage were P21 (3.1), MHA (2.5), RXU (2.5), RLP (1.3), KC (0.9), and PI (0.5). The MRS after thermocycling were MHA (2.5), P21 (2.2), RLP (1.8), KC (1.4), RXU (1.1), and PI (0.3). P21 had the highest MRS after 24-hour storage (P<.001), but after thermocycling MHA had the highest MRS (P<.001). RXU showed a significant decrease in MRS after thermocycling (P<.05). Cement residue was mostly retained on the zirconia abutments for P21, while for the other cements’ residue was retained on the lithium disilicate crowns.Conclusions
The cements tested presented a range of retentive strengths, providing the clinician with a choice of more or less retentive cements. MHA was the most retentive cement after thermocycling. Thermocycling significantly affected the retentive strengths of the P21 and RXU cements. 相似文献3.
Statement of problem
Resin cements are available in various shades from different manufacturers. However, there is no standard for the optical properties of these cements, which may result in differences in the color of translucent ceramic restorations.Purpose
The purpose of this in vitro study was to evaluate the effects of different shades and brands of resin cements on the color of a lithium disilicate ceramic.Materials and methods
Ten ceramic disks (11×1.5 mm, shade A2) were fabricated from lithium disilicate high-translucency blocks. Eighty cement disks (11×0.2 mm) were fabricated from 4 brands (Maxcem; Variolink; Clearfil; and RelyX) of resin cements in translucent and universal (shade A2) shades. Color measurements of ceramic specimens were made without (control) and with each brand/shade of resin cement material (test) with a spectrophotometer, and International Commission on Illumination Lab (CIELab) color coordinates were recorded. Color differences (ΔE00) between the control and test groups were calculated. ΔE00 results were analyzed by 2-way ANOVA and subsequent pairwise testing. Comparisons were performed using the Student t test, and then all P values were corrected with the step-down Bonferroni procedure (α=.05).Results
The effect on the ΔE00 values (P<.001) of the brand and shade of resin cement materials was significant. Both shades of RelyX cement groups had significantly lower and Variolink_translucent cement group had significantly higher ΔE00 results than other brands (P<.05). Only RelyX_translucent and RelyX_universal were significantly different from each other for comparisons within brands (P<.05). The effect of RelyX_universal cement on the ceramic was not visually perceptible (ΔE00≤1.30). Clinically unacceptable results (ΔE00>2.25) were observed only for Variolink_translucent cement (2.36).Conclusions
Same-shade resin cements from different manufacturers had different effects on the color of lithium disilicate ceramic. The effects of different shades of resin cements from the same manufacturer on the color of lithium disilicate ceramic were statistically different for only RelyX, which may also be considered clinically different based on clinical acceptability thresholds for color difference values (ΔE00). Accordingly, this effect may be considered clinically different for Variolink but not clinically different for Maxcem and Clearfil. 相似文献4.
Nijad R. Mina Nadim Z. Baba Fahad A. Al-Harbi Moataz F. Elgezawi Maha Daou 《The Journal of prosthetic dentistry》2019,121(2):306-310
Statement of problem
Data for the color stability of dual-polymerized and light-polymerized resin cements used in esthetic dentistry are lacking.Purpose
The purpose of this in vitro study was to evaluate the color stability of 4 types of composite resin cements after water aging.Material and methods
Specimens (n=30) of each resin cement (Variolink Esthetic LC, RelyX Ultimate DC, Nexus 3 DC, Nexus 3 LC) were prepared. The shade selected was Light+ for Variolink Esthetic, B 0.5 for RelyX Ultimate, and White for both Nexus 3 DC and LC. All 120 specimens were aged by water for 30 days at 37°C under dark conditions, using a thermocycling machine. The specimens’ color characteristics (L*, luminosity; a*, red-green; b*, yellow-blue) and color differences (ΔE) were measured with a spectrophotometer before day 0, after day 1, and after 30 days of immersion. Statistical analysis used ANOVA and Tukey post hoc tests (α=.05).Results
Considering ΔE<3.3 as clinically acceptable, results showed significant color variations for all cements (RelyX Ultimate=3.69; Nexus 3 LC=3.76; Nexus 3 DC=5.34), except for Variolink Esthetic (0.88). However, this variation was significantly less when day 1 was considered the baseline measurement, showing clinically acceptable ΔE values for all types of cement.Conclusions
Water aging had a significant effect on color stability; most color variations occurred in the first 24 hours of polymerization, with relatively nonsignificant variations afterwards. 相似文献5.
Abdulelah M. BinMahfooz Osama A. Qutub Thamer Y. Marghalani Mohammed F. Ayad Abdulhamaid A. Maghrabi 《The Journal of prosthetic dentistry》2018,119(6):1014-1020
Statement of problem
Studies on the degree of conversion of dental cement in relation to the number of methacrylate components are lacking.Purpose
The purpose of this in vitro study was to evaluate the degree of conversion of single- and multicomponent methacrylate-containing dental cements around opaque and translucent fiber dowels at varying depths.Material and methods
Teeth were prepared for standard endodontic therapy, and a dowel space was created. Opaque and translucent fiber dowels consisting of Aestheti-Plus (AP) and FiberKleer were cemented with 4 methacrylate (MA)-containing cements, including RelyX U100 (R), which contains TEGDMA; Duolink (D), which contains TEGDMA and BisGMA; and Variolink N LC (V) and Breeze (B), which contain TEGDMA, BisGMA, and UDMA. Light-emitting diode polymerization was performed for 60 seconds. The specimens were immediately cut into halves and measured within the first hour at depths of 1, 3, and 5 mm using Raman spectroscopy, and the degree of conversion (DC) of resin cement was calculated. Data were analyzed using 3-way ANOVA and the Tukey multiple comparison test (α=.05).Results
The measured dowel regions were not significantly different at various depths (P=.10). The dowel and cement types significantly influenced the degree of conversion of the cement (P<.05). The V and B cements exhibited a higher DC than D and R cements. With AP dowels, the DC of cement D was lower than that of the V, B, and R cements.Conclusions
Within the limitations of this in vitro study, the degrees of conversion of the tested resin cements were not affected by the tested dowel depths. Higher DC was found in cement with more than 2 types of flexible MA. Opaque dowels produced a lower DC than translucent dowels. 相似文献6.
Glen H. Johnson Xavier Lepe Amanda Patterson Oliver Schäfer 《The Journal of prosthetic dentistry》2018,119(5):826-832
Statement of problem
A composite resin cement and matching self-etch adhesive was developed to simplify the dependable retention of lithium disilicate crowns. The efficacy of this new system is unknown.Purpose
The purpose of this in vitro study was to determine whether lithium disilicate crowns cemented with a new composite resin and adhesive system and 2 other popular systems provide clinically acceptable crown retention after long-term aging with monthly thermocycling.Material and methods
Extracted human molars were prepared with a flat occlusal surface, 20-degree convergence, and 4 mm axial length. The axio-occlusal line angle was slightly rounded. The preparation surface area was determined by optical scanning and the analysis of the standard tessellation language (STL) files. The specimens were distributed into 3 cement groups (n=12) to obtain equal mean surface areas. Lithium disilicate crowns (IPS e.max Press) were fabricated for each preparation, etched with 9.5% hydrofluoric acid for 15 seconds, and cleaned. Cement systems were RelyX Ultimate with Scotch Bond Universal (3M Dental Products); Monobond S, Multilink Automix with Multilink Primer A and B (Ivoclar Vivadent AG); and NX3 Nexus with OptiBond XTR (Kerr Corp). Each adhesive provided self-etching of the dentin. Before cementation, the prepared specimens were stored in 35°C water. A force of 196 N was used to cement the crowns, and the specimens were polymerized in a 35°C oven at 100% humidity. After 24 hours of storage at 100% humidity, the cemented crowns were thermocycled (5°C to 55°C) for 5000 cycles each month for 6 months. The crowns were removed axially at 0.5 mm/min. The removal force was recorded and the dislodgement stress calculated using the preparation surface area. The type of cement failure was recorded, and the data were analyzed by 1-way ANOVA and the chi-square test (α=.05) after the equality of variances had been assessed with the Levene test.Results
The Levene test was nonsignificant (P=.936). The ANOVA revealed the mean removal stresses, and forces did not differ for RelyX Ultimate with Scotchbond Universal (3.9 MPa; 522 N) and Multilink Automix with Multilink Primer (3.7 MPa; 511 N); both differed significantly (P=.022) from the mean for NX3 Nexus with OptiBond XTR (2.9 MPa; 387 N). For all 3 cements, the modes of failure showed cement principally on the crown intaglio, and the chi-square analysis was nonsignificant (P=.601).Conclusions
IPS e.max Press (lithium disilicate) crowns were well retained (2.9-3.9 MPa; 387-522 N) by the 3 cement-adhesive combinations after 6 months of aging with monthly thermocycling. These results can serve as a basis for cement selection for this type of crown because the values significantly exceeded those for zinc phosphate. Cements using their matched dentin bonding agent as the ceramic primer were as successful as cements with a separate silane coupling agent. 相似文献7.
Camila S. Sampaio João Malta Barbosa Eduardo Cáceres Lindiane C. Rigo Paulo G. Coelho Estevam A. Bonfante Ronaldo Hirata 《The Journal of prosthetic dentistry》2017,117(6):784-791
Statement of problem
Few studies have investigated the volumetric polymerization shrinkage and film thickness of the different cementation techniques used to cement veneers.Purpose
The purpose of this in vitro study was to evaluate the volumetric polymerization shrinkage (VS) and film thickness (FT) of various cementation techniques through 3-dimensional (3D) microcomputed tomography (μCT).Material and methods
Forty-eight artificial plastic maxillary central incisors with standard preparations for veneers were provided by a mannequin manufacturer (P-Oclusal) and used as testing models with the manufacturer’s plastic veneers. They were divided into 8 groups (n=6): RelyX Veneer + Scotchbond Universal (RV+SBU); Variolink Esthetic LC+Adhese Universal (VE+ADU); Filtek Supreme Ultra Flowable + Scotchbond Universal (FF+SBU); IPS Empress Direct Flow + Adhese Universal (IEF+ADU); Filtek Supreme Ultra Universal + Scotchbond Universal (FS+SBU); IPS Empress Direct + Adhese Universal (IED+ADU); Preheated Filtek Supreme Ultra Universal + Scotchbond Universal (PHF+SBU); and Preheated IPS Empress Direct + Adhese Universal (PHI+ADU). Specimens were scanned before and after polymerization using a μCT apparatus (mCT 40; Scanco Medical AG), and the resulting files were imported and analyzed with 3D rendering software to calculate the VS and FT. Collected data from both the VS and FT were submitted to 1-way ANOVA (α=.05).Results
VE+ADU had the lowest volumetric shrinkage (1.03%), which was not significantly different from RV+SBU, FF+SBU or IEF+ADU (P>.05). The highest volumetric shrinkage was observed for FS+SBU (2.44%), which was not significantly different from RV+SBU, IED+ADU, PHF+SBU, or PHI+ADU (P>.05). Group RV+SBU did not differ statistically from the remaining groups (P>.05). Film thickness evaluation revealed the lowest values for RV+SBU, VE+ADU, FF+SBU, and IEF+ADU, with an average between groups of 0.17 mm; these groups were significantly different from FS+SBU, IED+ADU, PHF+SBU, and PHI+ADU (P>.05), with an average of 0.31 mm.Conclusions
Both the VS and the FT of direct restorative composite resins were higher than those of veneer cements and flowable composite resins, whether preheated or not preheated. 相似文献8.
Radek Mounajjed Thomas J. Salinas Tomas Ingr Basel Azar 《The Journal of prosthetic dentistry》2018,119(6):975-980
Statement of problem
The vertical marginal discrepancy of restorations can increase upon cementation, and poor marginal fit can lead to cement dissolution, marginal discoloration, microleakage, and secondary caries. The amount of increase is related to the type of luting cement used, but how lithium disilicate pressed crowns are affected by different resin cements is unclear.Purpose
The purpose of this in vitro study was to compare the effect of using different resin luting cements on the vertical marginal discrepancy of lithium disilicate pressed crowns.Material and methods
A total of 18 intact extracted mandibular third molars were disinfected in a solution of 10% formalin for 7 days and were then prepared to receive a ceramic crown. Impressions were made with polyvinyl siloxane and lithium disilicate pressed crowns made and cemented with 1 of 3 resin luting cements. The marginal discrepancy was measured at 4 points on the finishing line of each tooth, with optical microscopy at ×200 magnification before and after cementation. Statistical analysis was done with the Kruskal-Wallis test to compare the median marginal increase among the 3 groups (a=.05).Results
The least amount of marginal increase after cementation was with Harvard PremiumFlow cement, with an average marginal increase of 42 ±11 μm. RelyX Ultimate cement increased the margins by an average 45 ±29 μm. The highest marginal increase was found in the Enamel Plus HRi preheated composite resin group (116 ±47 μm).Conclusions
The marginal increase of pressed crowns cemented with preheated composite resin (Enamel Plus HRi) exceeded the clinically acceptable range of marginal discrepancy. 相似文献9.
Adriana Lemos Mori Ubaldini Ana Raquel Benetti Francielle Sato Renata Corrêa Pascotto Antonio Medina Neto Mauro Luciano Baesso Anne Peutzfeldt 《Dental materials》2018,34(7):1054-1062
Objective
To investigate the relationship between physicochemical interactions of resin luting cements with dentine and retention of fibre posts in root canals.Methods
Retention of fibre posts (RelyX Fiber Post) was assessed by the pull-out method. The diffusion zone of the cements and their chemical interaction with dentine were estimated by micro-Raman spectroscopy. Resin luting cements employing etch-and-rinse (Rely X Ultimate and Variolink II), self-etch (Rely X Ultimate and Panavia F2.0), or self-adhesive (RelyX Unicem 2) modes were investigated. Data were analyzed by analysis of variance followed by Tukey HSD tests.Results
The retention of the fibre posts decreased in the following order: RelyX Ultimate, etch-and-rinse mode > RelyX Unicem 2 ≥ RelyX Ultimate, self-etch mode ≥ Panavia F2.0 ≥ Variolink II (p < 0.05). One of the etch-and-rinse mode cements presented the deepest diffusion zone, while the other, along with the self-adhesive cement, produced the shallowest zone. Cements used in the self-etch mode showed intermediary diffusion into dentine (p < 0.05). All resin luting cements showed some degree of chemical interaction with dentine, the highest recorded for RelyX Ultimate used in the etch-and-rinse mode and the lowest for Panavia F2.0 (p < 0.05). The retention of fibre posts in the root canal could be attributed neither to the mode of interaction of the luting cements with dentine nor to their ability to diffuse into dentine.Significance
Chemical interaction between the resin luting cement and the dentine paired with adequate post pretreatment contribute positively to the retention of fibre posts. 相似文献10.
Jong-Eun Kim Ami Amelya Yooseok Shin June-Sung Shim 《The Journal of prosthetic dentistry》2017,117(6):755-761
Statement of problem
Intraoral scanners have been reported to have limited accuracy in edentulous areas. Large amounts of mobile tissue and the lack of obvious anatomic landmarks make it difficult to acquire a precise digital impression of an edentulous area with an intraoral scanner.Purpose
The purpose of this in vitro study was to determine the effect of an artificial landmark on a long edentulous space on the accuracy outcomes of intraoral digital impressions.Material and methods
A mandibular model containing 4 prepared teeth and an edentulous space of 26 mm in length was used. A blue-light light-emitting diode tabletop scanner was used as a control scanner, and 3 intraoral scanners were used as experimental groups. Five scans were made using each intraoral scanner without an artificial landmark, and another 5 scans were performed after application of an artificial landmark (a 4×3 mm alumina material) on the edentulous area. The obtained datasets were used to evaluate trueness and precision.Results
Without an artificial landmark on the edentulous area, the mean trueness for the intraoral scanner ranged from 36.1 to 38.8 μm and the mean precision ranged from 13.0 to 43.6 μm. With an artificial landmark on the edentulous area, accuracy was improved significantly: the mean trueness was 26.7 to 31.8 μm, and the mean precision was 9.2 to 12.4 μm.Conclusions
The use of an alumina artificial landmark in an edentulous space improved the trueness and precision of the intraoral scanners tested. 相似文献11.
Yooseok Shin Sungho Park Jeong-Won Park Kwang-Mahn Kim Young-Bum Park Byoung-Duck Roh 《The Journal of prosthetic dentistry》2017,117(1):109-115
Statement of problem
The marginal and internal discrepancies of computer-aided design and computer-aided manufacturing (CAD-CAM) endocrowns are unknown.Purpose
The purpose of this in vitro study was to evaluate the marginal and internal discrepancies of endocrowns with different cavity depths by measuring them with microcomputed tomography (μCT).Material and methods
Endocrowns (n=48) of 2 different cavity depths (2 mm and 4 mm) were fabricated in 2 different chairside CAD-CAM systems (CEREC AC and E4D). A μCT scan was made before and after cementation. For analysis of the marginal and internal discrepancies, reference points were selected in 2-dimensional views of 3 buccolingual cross-sections and 3 mesiodistal cross-sections. To calculate the total discrepancy volume, the μCT sections were reconstructed 3-dimensional views, and changes in volume and surface area were examined. Statistical analysis was performed using 2-way ANOVA with Bonferroni correction (α=.05).Results
An endocrown with a 4-mm cavity showed a larger marginal and internal volume than one with a 2-mm cavity. Cementation did not show significant differences in total discrepancy thickness. Discrepancies on the pulpal floor were largest in other sites. Both chairside CAD-CAM systems showed similar discrepancy in the endocrowns.Conclusions
Based on the present study, marginal and internal discrepancies increased depending on cavity depth. Cementation did not increase the dimension of the discrepancy between the restoration and the cavity wall. The discrepancy on the pulpal floor appeared to affect these results. 相似文献12.
Joon-Soo Kim Ji-Hyeon Bae Mi-Jung Yun Jung-Bo Huh 《The Journal of prosthetic dentistry》2017,117(6):775-783
Statement of problem
Recently, zirconia removal diamond rotary instruments have become commercially available for efficient cutting of zirconia. However, research of cutting efficiency and the cutting characteristics of zirconia removal diamond rotary instruments is limited.Purpose
The purpose of this in vitro study was to assess and compare the cutting efficiency, durability, and diamond rotary instrument wear pattern of zirconia diamond removal rotary instruments with those of conventional diamond rotary instruments. In addition, the surface characteristics of the cut zirconia were assessed.Material and methods
Block specimens of 3 mol% yttrium cation-doped tetragonal zirconia polycrystal were machined 10 times for 1 minute each using a high-speed handpiece with 6 types of diamond rotary instrument from 2 manufacturers at a constant force of 2 N (n=5). An electronic scale was used to measure the lost weight after each cut in order to evaluate the cutting efficiency. Field emission scanning electron microscopy was used to evaluate diamond rotary instrument wear patterns and machined zirconia block surface characteristics. Data were statistically analyzed using the Kruskal-Wallis test, followed by the Mann-Whitney U test (α=.05).Results
Zirconia removal fine grit diamond rotary instruments showed cutting efficiency that was reduced compared with conventional fine grit diamond rotary instruments. Diamond grit fracture was the most dominant diamond rotary instrument wear pattern in all groups. All machined zirconia surfaces were primarily subjected to plastic deformation, which is evidence of ductile cutting. Zirconia blocks machined with zirconia removal fine grit diamond rotary instruments showed the least incidence of surface flaws.Conclusions
Although zirconia removal diamond rotary instruments did not show improved cutting efficiency compared with conventional diamond rotary instruments, the machined zirconia surface showed smoother furrows of plastic deformation and fewer surface flaws. 相似文献13.
Hong-Keun Hyun Soojung Kim Changmin Lee Teo Jeon Shin Young-Jae Kim 《The Journal of prosthetic dentistry》2017,117(2):294-302
Statement of problem
Few studies have investigated the colorimetric distribution of gingival color, including the posterior area and alveolar mucosa.Purpose
The purpose of this in vivo study was to investigate the distribution of colorimetric values in different areas of gingiva and to determine its relationship to colorimetric findings of the tooth and skin in a young Korean population.Material and methods
Participants included 40 periodontally healthy adults (22 men and 18 women) 25 to 36 years of age. Commission Internationale de l'Eclairage values (CIELab: L* lightness, a* green-red, and b* blue-yellow) were measured using a colorimeter at a total of 23 sites for each participant, including attached gingiva (AG) and alveolar mucosa (AM) in the maxillary and mandibular and incisor and molar regions, maxillary central incisor, and skin points of the glabella, cheek, and inner upper arm.Results
AG showed higher L* and lower a* values than AM. AG demonstrated higher L* and lower a* values in the maxillary region than in the mandibular region and higher b* values in the incisor region than in the molar region. AM revealed higher L* and lower a* and b* values in the incisor region than in the molar region. Positive significant correlations were found for L* between the skin area and AM and for b* between the skin area and AG.Conclusions
The colorimetric values of AG and AM differ according to the area, possibly as a result of differences in anatomic and histologic distribution that influence optical properties. 相似文献14.
Lucas da Fonseca Roberti Garcia Elaine Cristina Voltolini Pontes Fernanda Gonçalves Basso Josimeri Hebling Carlos Alberto de Souza Costa Diana Gabriela Soares 《Clinical oral investigations》2016,20(7):1559-1566
Objectives
The aim of this study was to evaluate the transdentinal cytotoxicity of components released from different resin-based luting cements to cultured MDPC-23 odontoblast-like cells and human dental pulp cells (HDPCs).Materials and methods
Artificial pulp chamber (APC)/dentin disc sets were distributed into four groups according to the materials tested (n = 10), as follows: G1, control (no treatment); G2, resin-modified glass-ionomer cement (RelyX Luting 2); G3, self-adhesive resin cement (RelyX U200); and G4, conventional resin cement (RelyX ARC). The materials were applied to the occlusal surfaces (facing up) of the dentin discs adapted to the APCs. The pulpal surfaces of the discs were maintained in contact with culture medium. Then, an aliquot of 400 μL from the extract (culture medium + resin-based components that diffused through dentin) of each luting cement was applied for 24 h to HDPCs or MDPC-23 cells previously seeded in wells of 24-well plates. Cell viability analysis was performed by the MTT assay (1-way ANOVA/Tukey test; α = 5 %).Results
For MDPC-23 cells, RelyX ARC (G4) and RelyX Luting 2 (G2) caused greater reduction in cell viability compared with the negative control group (P < 0.05). Only the HDPCs exposed to RelyX ARC (G4) extract showed a tendency toward viability decrease (9.3 %); however, the values were statistically similar to those of the control group (G1) (P > 0.05).Conclusions
In accordance with the safe limits of ISO 10993-5:1999 (E) recommendations, all resin-based luting cements evaluated in this study can be considered as non-toxic to pulp cells.Clinical relevance
Cytotoxicity of resin-based luting cements is material-dependent, and the different protocols for the application of these dental materials to dentin may interfere with their cytotoxicity.15.
Vinícius C. Brigagão Luis F.D. Barreto Kellem A.S. Gonçalves Marina Amaral Rafael P. Vitti Ana C.C. Neves Laís R. Silva-Concílio 《The Journal of prosthetic dentistry》2017,117(6):792-798
Statement of problem
Despite the advances in materials and techniques, adhesion to dentin is challenging because of the complex composition of dentin’s mineral, organic, and fluid phases.Purpose
The purpose of this in vitro study was to evaluate the bond strength of 2 different resin cements (conventional and self-adhesive) with or without previous dentin sealing and the effect of interim cement.Material and methods
Forty-five molars were embedded into acrylic resin blocks and a flat dentin surface was exposed. Twenty teeth (n=5 per group) were treated with the conventional resin cement associated with etch-and-rinse or self-etch adhesive approaches, applied before (immediate dentin sealing) or after (delayed dentin sealing) the application/removal of interim cement. Another 25 teeth (n=5, per group) were treated with self-adhesive resin cement with (self-etch mode [immediate dentin sealing or delayed dentin sealing]) or without adhesive application. Furthermore, in the self-adhesive resin cement group, the application of polyacrylic acid for dentin etching before cementation was evaluated. Composite resin blocks were cemented onto flat, treated dentin surfaces, and the assemblies were sectioned into bar-shaped specimens for microtensile bond strength testing. The data were subjected to 1-way ANOVA followed by the post-hoc Tukey test (α=.05). The failure patterns were classified as cohesive, adhesive, or mixed.Results
The application of adhesive before interim cement (immediate dental sealing) promoted the highest values of bond strength for both resin cements (P<.001). For self-adhesive resin cement, polyacrylic acid-enhanced bond strength after the application of interim cement.Conclusions
The application of dental adhesive immediately after tooth preparation (immediate dentin sealing) and before the use of an interim cement promoted the highest values of bond strength to dentin with the resin cements tested. 相似文献16.
Necati Kaleli Duygu Sarac Safak Külünk Özgür Öztürk 《The Journal of prosthetic dentistry》2018,119(3):437-445
Statement of problem
In recent years, the use of resin-matrix ceramics and polyetheretherketone (PEEK) abutments has been suggested to absorb excessive stresses on dental implants. However, only a few studies have evaluated the effect of these materials on stress distribution in implants and peripheral bone structure.Purpose
The purpose of this finite element analysis was to evaluate the biomechanical behaviors of resin-matrix ceramics and PEEK customized abutments in terms of stress distribution in implants and peripheral bone.Material and methods
Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created by using the standard tessellation language (STL) data of original implant components. An anatomic customized abutment and a maxillary right second premolar crown were then modeled over the titanium base abutment. A bone block representing the maxillary right premolar area was created, and the implant was placed in the bone block with 100% osseointegration. Six different models were created according to combinations of restoration materials (translucent zirconia [TZI], lithium disilicate glass ceramic [IPS], polymer-infiltrated hybrid ceramic [VTE]), and customized abutment materials (PEEK and zirconia). In each model, the implants were loaded vertically (200 N) and obliquely (100 N). The stress distribution in the crown, implant, and abutments was evaluated through the von Mises stress analysis, and the stress distribution in the peripheral bone was examined through the maximum and minimum principal stress analyses.Results
The oblique load resulted in high stress values in the implant components, restorative crown, and cortical bone. Low stress values were observed in the VTE crowns. Zirconia customized abutments exhibited higher stress values than PEEK customized abutments. The stress distributions in the implant and peripheral bone were similar in all models.Conclusions
Changes in restoration and customized abutment material did not affect stress distribution in the implant and peripheral bone. 相似文献17.
Antigoni Stylianou John O. Burgess Perng-Ru Liu Daniel A. Givan Nathaniel C. Lawson 《The Journal of prosthetic dentistry》2017,117(1):116-123
Statement of problem
The clinical challenge of adhering cement to intracanal dentin is transmitting light to the most apical parts of root canals to allow more efficient polymerization of the cement.Purpose
The purpose of this in vitro study was to compare the cement-polymerizing ability, microstructure, and radiopacity of a new fiber optic post (iLumi fiber optic Post) with a clinically successful fiber post (DT Light Post).Material and methods
Polymerizing ability was compared using a modified depth-of-polymerization protocol. A split aluminum mold with a 12-mm cylindrical hole (diameter=4.7 mm) was filled with light-polymerized resin cement (Variolink Esthetic LC). Each fiber post (n=12) was positioned and light-polymerized on the coronal end for 60 seconds with a light-emitting diode polymerization light. Unpolymerized resin was dissolved with an organic solvent, and the weight and length of the polymerized resin cement were measured. Scanning electron microscopy was used to examine vertical and horizontal cross-sections. The radiopacity values of both the posts and 5 additional reference posts were evaluated using an aluminum step wedge.Results
The weight and length of the polymerized resin cement were significantly greater (P<.05) with the fiber optic post, which scanning electron microscopy showed to have a higher density of parallel fibers. The iLumi post demonstrated greater radiopacity among the tested fiber posts and a titanium alloy post.Conclusions
The iLumi fiber optic posts have a unique structural fiber composition and excellent radiopacity and light-transmitting ability that produce more complete polymerization of the resin cement than the DT Light posts. 相似文献18.
Mathew T. Kattadiyil Abdulaziz AlHelal Brian J. Goodacre 《The Journal of prosthetic dentistry》2017,117(6):721-728
Statement of problem
Computer-engineered complete dentures (CECDs) have significant potential as shown by recent reports of outcomes and specific applications. An understanding of complications and quality assessment factors associated with CECDs from compiled data is lacking in published reports.Purpose
The purpose of this systematic review was to determine the clinical complications and quality assessments related to CECDs.Material and methods
Electronic searches of publications in English from January 1984 to September 2016 were performed in MEDLINE and Cochrane databases, with the results enriched by manual searches and citation mining to address 2 population intervention comparison outcome (PICO) questions: what are the clinical complications associated with CECDs, and what are the quality assessments with CECDs?Results
A review of 5 selected articles (limited data) on CECDs revealed patient dissatisfaction related to overall outcome (25.49%), inadequate retention (20.73%), and esthetic concerns (15.09%) as common complications. Quality assessment factors that were used to report complications were identified.Conclusions
Patient dissatisfaction, inadequate retention, and inadequate esthetics were the most common complications with CECDs. The addition of a trial placement option for CECDs could result in a better clinical outcome, reducing the incidence of other complications related to occlusal vertical dimension, centric relationship, tooth arrangement, and esthetics, improving patient satisfaction, and reducing remakes. The difficulty in reading the digital preview for an objective assessment before fabrication is a unique but not a common, complication for CECDs. 相似文献19.
Juliana R.L. Alonso Fernanda G. Basso Débora L.S. Scheffel Carlos Alberto de-Souza-Costa Josimeri Hebling 《The Journal of prosthetic dentistry》2018,119(3):494.e1-494.e9
Statement of problem
Improved stability of the adhesive interface can be obtained using crosslinkers. However, research on the use of crosslinkers in root dentin is lacking.Purpose
The purpose of this in vitro study was to evaluate the effect of crosslinkers on the proteolytic activity of root dentin and on the bond strength of resin-cemented fiber posts.Material and methods
Single root canals were obtained from premolars (n=48) and endodontically treated before being divided into 4 groups: deionized water (control), 0.5 mol/L carbodiimide, 5% proanthocyanidin, or 5% glutaraldehyde. After removing the canal sealer, the dentin was etched with phosphoric acid, followed by water rinsing and the application of the crosslinkers for 60 seconds. Fiber posts were cemented using an adhesive (Single Bond 2) and resin cement (RelyX ARC). The roots were then transversally sectioned to obtain 1 mm thick specimens from the cervical, middle, and apical thirds and then aged for 24 hours or 9 months. Nine roots per group were used for the push-out test and 3 for determining the proteolytic activity of the root dentin by in situ zymography. Bond strength data were submitted to a mixed-model ANOVA and Bonferroni tests (α=.05).Results
Only proanthocyanidin negatively affected the 24-hour bond strength. After 9 months, a significant decrease in bond strength was seen for all groups, except for the crosslinked treated specimens from the cervical third of the root canal. Intense gelatinolytic activity was detected in the control group after 24 hours but was inhibited in the crosslinker-treated groups. Proteolytic activity was also not detected after 9 months for the groups treated with the crosslinkers, irrespective of the root canal third. Conversely, proteolytic activity increased for the specimens from the control group.Conclusions
Although no proteolytic activity was detected in the hybrid layers along the entire root canal, dentin biomodification with crosslinkers was effective in preventing bond strength loss only in the cervical third. 相似文献20.
Kathleen M. Ross Jason S. Mehr Rebecca D. Greeley Lindsay A. Montoya Prathit A. Kulkarni Sonya Frontin Trevor J. Weigle Helen Giles Barbara E. Montana 《Journal of the American Dental Association (1939)》2018,149(3):191-201