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1.
Vitor Guarçoni de Paula Gerson Bonfante Fabio C. Lorenzoni Paulo G. Coelho Leonardo Rigoldi Bonjardim Vinicius P. Fardin Estevam A. Bonfante 《Dental materials》2019,35(3):511-522
Objective
To evaluate the probability of survival of monolithic and porcelain veneered lithium disilicate crowns comprised by a conventional or modified core when loaded on marginal ridges.Methods
Lithium disilicate molar crowns (n = 30) were fabricated to be tested at mesial and distal marginal ridges and were divided as follows: (1) bilayered crowns with even-thickness 0.5 mm framework (Bi-EV); (2) bilayered crowns with modified core design (Bi-M-lingual collar connected to proximal struts), and: (3) monolithic crowns (MON). After adhesively cemented onto composite-resin prepared replicas, mesial and distal marginal ridges of each crown (n = 20) were individually cyclic loaded in water (30–300 N) with a ceramic indenter at 2 Hz until fracture. The 2-parameter Weibull was used to calculate the probability of survival (reliability) (90% 2-sided confidence bounds) at 1, 2, and 3 million cycles and mean life.Results
The reliability at 1 and 2 million cycles was significantly higher for MON (47% and 19%) compared to Bi-EV (20% and 4%) and Bi-M (17% and 2%). No statistical difference was found between bilayered groups. Only the MON group presented crown survival (7%) at 3 million cycles. The mean life was highest for MON (1.73E + 06), lowest for Bi-M (573,384) and intermediate for Bi-E (619,774). Fractographic analysis showed that the fracture originated at the occlusal surface. The highest reliability was found for MON crowns. The modified framework design did not improve the fatigue life of crowns.Significance
Monolithic lithium disilicate crowns presented higher probability of survival and mean life than bilayered crowns with modified framework design when loaded at marginal ridges. 相似文献2.
Khaled E. Ahmed Ting Wang Kar Yan Li Wai Kuen Luk Michael F. Burrow 《Journal of prosthodontic research》2019,63(2):167-172
Purpose
To assess the average full-arch scanning time, perception and likelihood of future adoption of technology by final-year dental students using three different Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) intraoral scanning systems.Methods
Final-year undergraduate Dental Students (FDS), with no prior experience of intraoral scanning, full-arch scanned (IOS) a mannequin head-mounted model under supervision. Three scanning systems were used, TRIOS Colour (TRIOS); True Definition (TDef); and CEREC AC OmniCam (CEREC). Thereafter, FDS completed a questionnaire to assess their perception of IOS. Data were analysed by Generalized Estimating Equations, Fisher’s exact tests and logistic regression.Results
Forty-nine FDS participated. Average full arch IOS time varied significantly (p < 0.001) among the TRIOS, CEREC, and TDef, at 4 min (n = 48), 4 min 42 s (n = 33), and 7 min 32 s (n = 41) respectively. IOS using the TRIOS was significantly (p < 0.001) the quickest, while TDef was the slowest (p < 0.001). Seventy-one percent of FDS had positive overall IOS experience. FDS who reported intraoral scanning was timesaving compared with conventional impressions were more likely to adopt the technology after graduation (odds ratio (OR) = 11.91, 95% confidence interval (CI) = 2.56–55.45, p = 0.002).Conclusions
Intraoral scanning performance of novice users varied significantly and was dependent on the scanning system used. The questionnaire showed that the overall IOS experience was positive amongst FDS. The perception of time-saving, when using IOS versus conventional impression methods, determined the likelihood of future adoption of the technology. 相似文献3.
Ana Maria Estivalete Marchionatti Vinícius Felipe Wandscher Iana Lamadrid Aurélio César Dalmolin Bergoli Liliana Gressler May 《Dental materials》2019,35(4):e63-e73
Objective
To compare file-splitting multilayer (fused and cemented) with monolithic Y-TZP on the fatigue flexural strength and finite element analysis (FEA) stresses. Additionally, to verify the effect of the material under tension in multilayer Y-TZP.Methods
Disc-shaped (diameter: 14.4 mm; thickness: 1.4 mm) monolithic Y-TZP (IPS e.max ZirCAD — Ivoclar Vivadent) and trilayer specimens with Y-TZP framework (IPS e.max ZirCAD), intermediate layer of fusion ceramic (IPS e.max CAD Crystall./Connect) or resin cement (Multilink Automix) and lithium disilicate veneer (IPS e.max CAD) were divided into five groups (n = 20): monolithic Y-TZP (M), fused file-splitting with framework under tension (F-FT), cemented file-splitting with framework under tension (C-FT), fused file-splitting with veneer under tension (F-VT) and cemented file-splitting with veneer under tension (C-VT). Fatigue flexural strength was determined (piston-on-three ball) by the staircase approach (750,000 cycles; 20 Hz). Mean and confidence intervals (CI) were calculated. FEA was evaluated under the application of the experimental mean fatigue load.Results
The fatigue strength was statistically different for all groups. Means and CI (MPa) were: M — 405.92 (CI 397.58–414.26), F-FT — 377.73 (CI 374.59–380.88), C-FT — 346.54 (CI 340.62–352.46), F-VT — 154.79 (CI 151.86–157.72) and C-VT — 100.34 (CI 97.42–103.26). FEA tensile stresses were similar to the mean experimental values (up to ?10 MPa of variation), with the most discrepant calculated stresses for C-FT (?20 MPa higher than experimental result).Significance
Monolithic specimens showed the highest flexural fatigue strength and fused file-splitting resulted in higher fatigue strength than cemented file-splitting. Groups with the framework under tension exhibited higher flexural fatigue strength. 相似文献4.
Christina Boutsiouki Roland Frankenberger Susanne Lücker Norbert Krämer 《Dental materials》2019,35(3):422-433
Objective
To investigate secondary caries inhibition after dentine pre-treatment with 2% CHX, experimental addition of CHX in primer and adhesive of a 3-step adhesive system, and industrial addition od CHX in a 2-step adhesive system.Materials and method
Sixty Class-V cavities were restored according to the adhesive protocol (n = 12): 1) control group, Scotchbond Multi-Purpose, 3M (CTRL), 2) 2% CHX dentine pre-treatment (DENT), 3) 0.1% CHX in primer (PRIM), 4) 0.1% CHX in bonding agent (BOND), 5) Peak Universal Bond including 0.2% CHX (PEAK). Specimens were thermocycled (10,000 cycles) and inserted into a Streptococcus mutans biofilm artificial mouth (caries model). The 10-day biological loading protocol consisted of consecutive phases of demineralisation (1 h) and remineralisation (5 h). Evaluation under a fluorescence microscope (demineralisation) and an SEM (marginal gap) followed, at restoration margins, and at 0.3 mm and 0.5 mm distance from the margins, in enamel and in dentine. Total demineralization was calculated as the sum of demineralisation and substance loss due to demineralisation.Results
PRIM (p = 0.007, mod. LSD), BOND (p = 0.012, mod. LSD) and PEAK (p = 0.008, mod. LSD) exhibited significantly higher total demineralisation values in enamel margins than CTRL. No significant differences were noted for total demineralisation in dentine. Regarding marginal gaps, DENT exhibited significantly lower enamel gap values compared to all other groups (p = 0.001).Conclusions
2% CHX as dentine pre-treatment, 0.1% or 0.2% CHX added in adhesives did not provide any antibacterial effect regarding secondary caries in dentine. On the other hand, 2% CHX dentine pre-treatment managed to limit marginal gap formation in enamel compared to the other adhesive protocols in the study. 相似文献5.
Tomoaki Mameno Masahiro Wada Yoshinobu Onodera Daiju Fujita Hironobu Sato Kazunori Ikebe 《Journal of prosthodontic research》2019,63(2):216-220
Purpose
The purpose of this study was to evaluate the incidence of peri-implantitis and to identify potential associated risk indicators.Methods
This longitudinal study included 477 patients treated with 1420 implants. Medical and dental histories were evaluated in all patients. The location, size, connection type, surgical protocol, use of prosthesis splinting and fixation type were evaluated for each implant. In peri-implant evaluation, minimum keratinized tissue width around implants, peri-implant probing depths, peri-implant bleeding and peri-implant suppuration were assessed. Bone resorption around implants was evaluated with intraoral radiographs at baseline and at follow-up examinations. The study endpoint was peri-implantitis, which was defined as the presence of bleeding on probing and/or suppuration with bone resorption >1 mm, in accordance with previous studies. Data were analyzed with mixed-effects Cox models.Results
Peri-implantitis occurred in 15.3% of patients and 9.2% of implants. The overall 5- and 10-year cumulative implant survival rates were 0.95 (95% confidence interval [CI]: 0.93–0.96) and 0.83 (95% CI: 0.8–0.87), respectively. Age (hazard ratio [HR] = 0.94, 95% CI: 0.90–0.98, p < 0.01), plaque control record >20% (HR = 2.61, 95% CI: 1.02–6.67, p = 0.04), maxillary placement (HR = 1.90, 95% CI: 1.11–3.23, p = 0.02) and number of occlusal supports (HR = 0.87, 95% CI: 0.77–0.99, p = 0.03) were significantly correlated with peri-implantitis development.Conclusions
Within the limitations of this longitudinal study on risk indicators for peri-implantitis, age, inadequate plaque control, insertion in the maxilla and less occlusal support of natural teeth correlated with peri-implantitis development. 相似文献6.
Kazuhiro Nagata Satol Hori Ryo Mizuhashi Tomoko Yokoe Yojiro Atsumi Wataru Nagai Motoatu Goto 《Journal of prosthodontic research》2019,63(2):202-209
Purpose
Manual therapy has been used for the treatment of patients with temporomandibular disorders (TMD) with mouth-opening limitations. However, the curative effect of manipulation differs among researchers, and its necessity remains controversial. The purpose of this study was to confirm the efficacy of manipulation using a randomized controlled trial (RCT).Methods
A total of 61 TMD patients who had mouth-opening limitation (upper and lower middle incisor distance ≤35 mm) were selected. They were divided into two treatment groups: conventional treatment (n = 30) and conventional treatment plus manipulation (n = 31). The conventional treatment included two types of self-exercise: cognitive behavioral therapy for bruxism and education. Mouth-opening limitation, orofacial pain, and temporomandibular joint (TMJ) sounds were recorded from baseline to 18 weeks after baseline. These parameters were statistically compared between the two treatment groups by using analysis of variance (ANOVA) and Scheffe’s test to assess mouth opening distance and pain; TMJ sounds were compared using Mann–Whitney U test.Results
No statistical difference was observed between the two treatment groups except for mouth-opening limitation after treatment at the first visit. Subgroup analyses, stratified according to the pathological type of TMD, indicated a similar trend.Conclusions
The efficacy of manipulation seems to be limited, in contrast to our expectations, and improved execution of therapeutic exercises has a similar effect to that of manipulation during long-term observation. The advantage of manipulation was observed only during the first treatment session. The RCT was registered in the University Hospital Medical Information Network in Japan (UMIN-CTR: 000010437). 相似文献7.
Deyar Jallal Hadi Mahmood Michael Braian Christel Larsson Ann Wennerberg 《Dental materials》2019,35(3):486-494
Objectives
To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive.Methods
Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student’s t-test.Results
There were significant differences in mean values for accuracy/production tolerance among different manufacturing techniques for both production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p ≤ .001) and conventional wax copings (p ≤ .001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p ≤ .001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p ≤ .001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p ≤ .001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025).Significance
The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique. 相似文献8.
Akihisa Kodaira Hiroyasu Koizumi Hiroshi Nogawa Kentaro Okamura Mitsuo Nakamura Takayuki Yoneyama 《Journal of prosthodontic research》2019,63(2):145-149
Purpose
The aim of this study was to evaluate the shear bond strength and durability of MMA-TBB resin to human enamel applied a self-etching primer with phosphoric acid etching.Methods
A self-etching primer (Teeth primer, TP) containing 4-methacryloyloxyethyl trimellitate anhydride (4-META) and sodium sulfite and two etchants having different phosphoric acid concentrations (K-etchant gel, KE, 35–45%: Red gel, RG, 20–25%) were used as treatment agent, and MMA-TBB resin was used as luting agent. Enamel surfaces were treated with six methods which were as follow: KE, RG, TP, KE + TP, and RG + TP. After enamel specimens were bonded with MMA-TBB resin and stored in distilled water for 24 h, the shear bond strength test was done at 0 thermocycling or 20,000 thermocycling. These results were statistically verified with Steel-Dwass multiple comparisons and Man–Whitney U test.Results
The shear bond strength of TP group, KE + TP group, and RG + TP group were significantly higher than KE group and RG group in pre-thermocycling. KE + TP group and RG + TP group were significantly higher than other groups in post-thermocycling.Conclusions
Applying TP with phosphoric acid etching can increased shear bond durability despite difference of phosphoric acid concentrations (35–45% or 20–25%). 相似文献9.
Effect of indirect restorative material and thickness on light transmission at different wavelengths
Rafael Rocha Pacheco Adriana Oliveira Carvalho Carolina Bosso André Ana Paula Almeida Ayres Renata Bacelar Catanhede de Sá Tiago Monteiro Dias Frederick Allen Rueggeberg Marcelo Giannini 《Journal of prosthodontic research》2019,63(2):232-238
Purpose
The aim of this study was to evaluate the influence of indirect restorative material type and thickness on the transmission of different wavelengths from a broad-banded dental curing light.Methods
Four dental indirect restorative materials for computer-aided design and computer-aided manufacturing (CAD/CAM) were evaluated: [RC] resin/ceramic hybrid material (Lava Ultimate), [FC] feldspathic ceramic (VitaBlocs), and two zirconia-based ceramics ([ZK] Katana; and [ZL] Lava). Total loss of irradiance (TL) was measured for blue (WB, 425–490 nm) and violet (WV, 350–425 nm) wavelengths. Specimens of 15 × 15 mm with varying thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were fabricated (n = 5). A plasma-arc dental light-curing unit was used (Arc Light-II). To assess TL as a function of wavelength, a software (Spectra Suite v5.1) connected to a spectroradiometer (USB2000) and an integrating sphere (CTSM-LSM-60-SF) was used. Data was subjected to statistical analysis (two-way ANOVA and post-hoc Tukey test, α = 0.05).Results
A 0.5 mm interposition resulted in TL from 50.5 to 67.2%, depending on material. Increased thickness resulted in higher TL for all materials. FC showed less TL compared to ZK. In general, WV showed higher TL than did WB, and WV/WB proportion decreased with increasing thickness.Conclusions
Indirect materials significantly reduced TL, and this effect is greater with increasing thickness. WV showed lower penetration compared to WB. 相似文献10.
Shruti Vidhawan Agarwalla Kassapa Ellepola Mariana Caldeira Ferraz da Costa Guilhermino José Macêdo Fechine Julien Luc Paul Morin A.H. Castro Neto Chaminda Jayampath Seneviratne Vinicius Rosa 《Dental materials》2019,35(3):403-413
Objective
To evaluate the surface and wettability characteristics and the microbial biofilm interaction of graphene coating on titanium.Methods
Graphene was deposited on titanium (Control) via a liquid-free technique. The transfer was performed once (TiGS), repeated two (TiGD) and five times (TiGV) and characterized by AFM (n = 10), Raman spectroscopy (n = 10), contact angle and SFE (n = 5). Biofilm formation (n = 3) to Streptococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans was evaluated after 24 h by CV assay, CFU, XTT and confocal microscopy. Statistics were performed by one-way Anova, Tukey’s tests and Pearson’s correlation analysis at a pre-set significance level of 5 %.Results
Raman mappings revealed coverage yield of 82 % for TiGS and ≥99 % for TiGD and TiGV. Both TiGD and TiGV presented FWHM > 44 cm?1 and ID/IG ratio < 0.12, indicating multiple graphene layers and occlusion of defects. The contact angle was significantly higher for TiGD and TiGV (110° and 117°) comparing to the Control (70°). The SFE was lower for TiGD (13.8 mN/m) and TiGV (12.1 mN/m) comparing to Control (38.3 mN/m). TiGD was selected for biofilm assays and exhibited significant reduction in biofilm formation for all microorganisms compared to Control. There were statistical correlations between the high contact angle and low SFE of TiGD and decreased biofilm formation.Significance
TiGD presented high quality and coverage and decreased biofilm formation for all species. The increased hydrophobicity of graphene films was correlated with the decreased biofilm formation for various species. 相似文献11.
Junji Iwata Masaki Asakura Tatsuhide Hayashi Shozo Tsuruta Miki Hori Yoshinori Nagase Akimichi Mieki Seiji Ban Tatsushi Kawai 《Journal of prosthodontic research》2019,63(2):221-226
Purpose
Immersion tests in purified water were conducted to evaluate the leaching behaviors of filler elements contained in computer-aided design/computer-aided manufacturing (CAD/CAM) composite resin.Methods
Four commercial CAD/CAM resin composite blanks were tested: Shofu block HC 2 layer, Cerasmart, Katana Avencia block, and KZR-CAD HR Block 2. The specimens in the size of 10.0 × 12.0 × 2.0 mm were immersed in a 50-mL conical tube containing 40 mL of purified water, and then placed in a constant-temperature oven set at a temperature of 37, 60, 70, or 80° C and stored statically for 30 days. After storage, the concentrations of leached elements in the immersion solution were measured with an inductively coupled plasma atomic emission spectrometer. To characterize the surface of the specimen after the immersion test, secondary electron images were obtained.Results
The immersion test resulted in the leaching of Si, the main component, from all materials tested. Some materials were found to have leached high amount of Ba or Sr in addition to Si, and remarkable surface degradation was observed. The amount of leached elements increased with increased immersion temperatures.Conclusions
Filler elements in CAD/CAM composite resins used in this study leached into purified water. The leached elements and its quantities greatly differed among materials and depend on the types of the oxides composing the filler. The amounts of leached elements varied in a temperature-dependent manner. 相似文献12.
Objectives
Alignment procedures have yet to be standardised and may influence the measurement outcome. This investigation assessed the accuracy of commonly used alignment techniques and their impact on measurement metrics.Methods
Datasets of 10 natural molar teeth were created with a structured-light model-scanner (Rexcan DS2, Europac 3D, Crewe). A 300 μm depth layer was then digitally removed from the occlusal surface creating a defect of known size. The datasets were duplicated, randomly repositioned and re-alignment attempted using a “best-fit” alignment, landmark-based alignment or reference alignment in Geomagic Control (3D Systems, Darmstadt, Germany). The re-alignment accuracy was mathematically assessed using the mean angular and translation differences between the original alignment and the re-aligned datasets. The effect of the re-alignment on conventional measurement metrics was calculated by analysing differences between the known defect size and defect size after re-alignment. Data were analysed in SPSS v24(ANOVA, post hoc Games Howell test, p < 0.05).Results
The mean translation error (SD) was 139 μm (42) using landmark alignment, 130 μm (26) for best-fit and 22 μm (9) for reference alignment (p < 0.001). The mean angular error (SD) between the datasets was 2.52 (1.18) degrees for landmark alignment, 0.56 (0.38) degrees for best-fit alignment and 0.26 (0.12) degrees for reference alignment (p < 0.001). Using a reference alignment statistically reduced the mean profilometric change, volume change and percentage of surface change errors (p < 0.001).Significance
Reference alignment produced significantly lower alignment errors and truer measurements. Best-fit and landmark-based alignment algorithms significantly underestimated the size of the defect. Challenges remain in identifying reference surfaces in a robust, clinically relevant method. 相似文献13.
Objective
The objectives of the present study were: (1) to analyze the dispersion and optical properties of suspensions with various volume fractions of zirconia, and (2) to assess the influence of zirconia volume fraction on the microstructure and physical properties of products produced by the additive manufacturing and sintering process.Methods
Zirconia specimens were fabricated by an additive manufacturing technique using a DLP (digital light processing) system. The zirconia suspensions were divided into six groups based on zirconia volume fraction within the range of 48–58 vol%.Results
The maximum volume fraction of zirconia in suspensions possible for printing was 58 vol%. The cure depth of the zirconia suspensions decreased as the volume fraction increased. The cure depth was greater than 100 μm after 15 s photocuring in all groups. Geometrical overgrowth tended to increase gradually as the volume fraction of zirconia increased within the range of 28.55–36.94%. The 3-point bending strength of the specimens increased as the volume fraction of zirconia in the suspension increased, reaching a maximum value of 674.74 ± 32.35 MPa for a volume fraction of 58 vol%. Cracks were observed on the surfaces of zirconia specimens and these cracks increased in number as zirconia volume fraction decreased.Significance
In this experiment, the viscosity of zirconia suspensions sharply increased from a volume fraction of 54 vol%. Because of the very high viscosity, 58 vol% was the maximum volume fraction possible for additive manufacturing. After polymerization, all specimens showed some distortion due to geometrical overgrowth. The maximum 3-point bending strength was 674.74 ± 32.35 MPa for a volume fraction of 58 vol%. But the maximum strength of sintered zirconia prepared by additive manufacturing is inferior to that of conventionally sintered zirconia. 相似文献14.
Purpose
To evaluate the literature on the stability of open bite treatment using extraction or non-extraction methods.Methods
Medline, Scopus, and Cochrane library were electronically searched until December 2017. Studies were considered for evaluation if they reported overbite measurements pre-treatment, post-treatment, and at least 1-year post-retention for non-surgical orthodontic patients with permanent dentition, treated by extraction or non-extraction methods The risk of bias of the selected articles was assessed.Results
The search retrieved 985 articles, only 6 articles were included after applying the selection criteria. Two articles were case-control studies, and the other four were case series studies. The mean stability rates were 93.53% and 73.68% in extraction and non-extraction cases, respectively. Because each included study presented data of either the extraction or non-extraction method, it was not possible to perform a meta-analysis by pooling the results of the studies to compare the two methods. However, meta-analysis was conducted to compare the overbite between post-treatment and post-retention within each method. The results showed no significant change in extraction cases (mean difference (MD) 0.49, 95% CI ?0.18–1.16; P = 0.15), but showed a significant change in non-extraction cases (MD 1.12, 95% CI 0.77–1.46; P < 0.00001).Conclusions
Our findings indicated no significant relapse in extraction cases, but a significant relapse in non-extraction cases. However, due to no direct comparison, the optimum treatment method for open bite patients with permanent dentition remains questionable. Further studies with a high level of evidence that compare both treatment methods are needed to draw a definitive conclusion. 相似文献15.
Jin Feng Lei Cheng Xuedong Zhou Hockin H.K. Xu Michael D. Weir Qian Li Matthias Hannig Stefan Rupf 《Dental materials》2019,35(3):434-443
Objectives
The aims of this study were to investigate the effects of water aging for up to 6 months on the mechanical and anti-biofilm properties of a novel antibacterial glass ionomer cement (GIC) containing dimethylaminododecyl methacrylate (DMADDM).Methods
GIC specimens (n = 180) which contained DMADDM (0 wt.%, 1.1 wt.% or 2.2 wt.%) were prepared. The mechanical properties surface roughness, microhardness and the surface charge density of ammonium groups were measured before and after water aging for 3 and 6 months at 37 °C. Further six months aged specimens (n = 216) were worn by 6 volunteers in their oral cavities for 24 h and 72 h. Biofilm formation was analyzed and rated by fluorescence microscopy (FM) and by scanning electron microscopy (SEM). Biofilm viability was analyzed by FM.Results
Water aging did not show any adverse effects on the surface roughness and hardness of the material. The surface charge density of the GIC samples containing DMADDM decreased due to the aging procedure, however, was still higher than that of the GIC without DMADDM. In situ biofilm formation was significantly reduced after 24 h on DMADDM containing GIC (p < 0.05). FM results showed a higher ratio of red/green fluorescence on GIC-DMADDM samples.Significance
Incorporating DMADDM into GIC affected the material properties in a tolerable manner even after 6 months of storage in water. The new GIC is a promising material to affect the biofilm formation on the surface of restorations. 相似文献16.
Tomohide Kondo Futoshi Komine Junichi Honda Hiroki Takata Yuta Moriya 《Journal of prosthodontic research》2019,63(2):140-144
Purpose
To determine the effect of veneering material and framework design on fracture loads of implant-supported zirconia molar fixed dental prostheses (FDPs).Methods
Sixty-six zirconia FDPs were manufactured onto two implants and classified as uniform thickness (UT) or anatomic design (AD). These framework design groups were then further divided into three subgroups (n = 11): feldspathic porcelain-veneered zirconia FDPs (PVZ), indirect composite-veneered zirconia FDPs (IVZ), and metal–ceramic FDPs (MC). The FDPs were luted on the implant abutments and underwent fracture load testing. Significant differences were assessed by the Kruskal–Wallis test and Mann–Whitney U-test (α = 0.05).Results
For UT group, median fracture load was significantly higher for the IVZ (1.87 kN) and MC (1.90 kN) specimens than for the PVZ specimens (1.38 kN) (p < 0.05). In the AD group, the IVZ specimens had the highest median fracture load (4.10 kN) of the three groups tested. The AD group exhibited higher median fracture loads than the UT group in all subgroups.Conclusions
Indirect composite appears to be a useful alternative to feldspathic porcelain as the layering material for implant-supported zirconia FDPs. The AD group had higher fracture loads than UT group. In addition, implant-supported indirect composite-veneered zirconia-based FDPs appear to be clinically feasible. 相似文献17.
Falk Schwendicke Allam Al-Abdi Agustín Pascual Moscardó Alvaro Ferrando Cascales Salvatore Sauro 《Dental materials》2019,35(5):772-779
Objectives
The aim of this study was to evaluate the remineralization effects of conventional and experimental ion-releasing materials on different artificial dentin carious lesions.Methods
Forty human dentin discs were submitted to different demineralization protocols for simulated caries lesion: (D1) Shallow chemically-induced caries, (D2) deep chemically-induced caries, (D3) deep bacterially-induced caries. Each disc was divided in five parts; one of those served as baseline control. The remaining parts of each disc (n = 12–16/group) were treated using the following materials: EXP, an experimental resin-based bioactive material consisting of a self-etch primer and an adhesive containing a fluoride-doped bioglass; GIC, a glass ionomer cement (Riva LC); MTA, Mineral Trioxide Aggregate (ProRoot MTA); BIO, a calcium silicate cement (Biodentine). Specimens were mounted in a dual-chamber device to simulate the exposure to pulpal pressure and oral fluids. After 3 months, mineral and mechanical gains were assessed using transverse microradiography (vol%?×?μm) and microhardness measurements (VHN). Characterization using confocal microscopy and transmission electron microscopy (TEM) was also performed.Results
All four restorative materials induced mineral gains regardless of the protocol for caries lesion, without significant differences between materials. Microhardness significantly increased in the groups BIO and MTA, but not GIC; EXP only provided hardness gains in D3-lesions. Fluorescence and confocal microscopy confirmed these results. There was a clear “top-down” remineralization in the groups BIO and MTA, and “bottom-up” intrafibrillar collagen remineralization in EXP.Significance
Mineral gains did not always translate into hardness gains. Biodentine and MTA induced evident mineral precipitation, but intra/inter-fibrillar collagen mineral infiltration was only provided by biomimetic remineralisation via the use of the experimental adhesive. Complete remineralization of caries lesions remains a challenge. 相似文献18.
Thwe Zin Ei Yasushi Shimada Ahmed Abdou Alireza Sadr Masahiro Yoshiyama Yasunori Sumi Junji Tagami 《Dental materials》2019,35(4):e74-e82
Objective
The purpose of this study was to detect and investigate the association of enamel microcracks with demineralization at proximal contact areas of premolars, using 3D swept-source optical coherence tomography (SS-OCT).Methods
Extracted maxillary and mandibular premolars (n = 50 each), without any visible tooth cracks, were examined for demineralization of interproximal contact areas, using the International Caries Detection and Assessment System (ICDAS). SS-OCT was used to evaluate demineralization and detect microcracks. Demineralization progression was divided into 4 types by depth: 0 for sound enamel and Type I, II, and III for enamel demineralization penetrating into the outer third, the middle third, and the inner third of the enamel thickness, respectively. Enamel microcracks were classified according to the predominant crack pattern: Type O, no cracks; Type A, subsurface microdefects; Type B, enamel microcrack running along the direction of the enamel prism; Type C, enamel microcrack running transverse to the enamel prism direction; and Type D, a combination of patterns A, B, and C. SS-OCT findings were confirmed by confocal laser scanning microscopy observation.Results
Microcracks confined within the superficial enamel in proximal contact areas were seen as bright lines on SS-OCT. There were significant positive correlations among ICDAS codes, demineralization levels, and microcrack distribution (p ≤ 0.001). The mesial side of maxillary premolars showed significantly more demineralization (n = 36) and microcracks (n = 27) than that of the mandibular premolars (n = 20 and n = 14, respectively; p < 0.001).Significance
The presence of microcracks within the superficial enamel in proximal contact areas could be determined using SS-OCT, and correlated with the level of demineralization. 3D SS-OCT is a valuable diagnostic tool for comprehensive assessment of microstructural changes related to enamel demineralization and crack development. 相似文献19.
Shinobu Yamauchi Shoko Miura Shin Kasahara Jirun Sun Hiroshi Egusa 《Journal of prosthodontic research》2019,63(2):184-192
Purpose
To investigate the influence of firing condition and thickness of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) frame on the fracture toughness of veneering ceramics.Methods
Layering and pressable ceramics without frames or on 0.8- and 1.2-mm-thick Y-TZP frames were fired with 5 schedules (normal and 4 customized conditions). The fracture toughness of the ceramics was measured at 0.5–2.5 mm from the frame by the indentation fracture method. Crystal structures at the measurement points were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).Results
Under customized firing conditions, the fracture toughness of the layering ceramic significantly decreased, particularly near the frame. Use of a 1.2-mm-thick frame significantly decreased the fracture toughness of both layering and pressable ceramics compared to ceramics without the frame. The decreased fracture toughness only occurred close (0.5 and 1.0 mm) to the frame. XRD analysis showed identical diffraction patterns between points near and far from the frame, suggesting that the decreased fracture toughness was not due to crystal defects or impurities. SEM revealed many microcracks and large crystals in layering ceramic near the 1.2-mm-thick frame, possibly resulting from the thermal properties of the zirconia frame, such as large heat capacity and low thermal conductivity.Conclusions
Modification of the firing conditions from the manufacturer’s instructions and inclusion of a thick Y-TZP frame decreased the fracture toughness of veneering ceramics at the interface, suggesting that a thick frame would pose a potent fracture risk in veneering ceramics used for zirconia-based all-ceramic restorations. 相似文献20.
Rafael Menezes-Silva Bruna Medeiros Bertol de Oliveira Paulo Henrique Martins Fernandes Lívia Yukari Shimohara Fabiano Vargas Pereira Ana Flávia Sanches Borges Marília Afonso Rabelo Buzalaf Renata Corrêa Pascotto Sharanbir K. Sidhu Maria Fidela de Lima Navarro 《Dental materials》2019,35(4):564-573