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1.
Goran I. Benic Irena Sailer Marco Zeltner Janine N. Gütermann Mutlu Özcan Sven Mühlemann 《The Journal of prosthetic dentistry》2019,121(3):426-431
Statement of problem
Trials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking.Purpose
The purpose of the third part of this clinical study was to test whether the fit of zirconia 3-unit frameworks for fixed partial dentures fabricated with fully digital workflows differed from that of metal frameworks fabricated with the conventional workflow.Material and methods
In each of 10 participants, 4 fixed-partial-denture frameworks were fabricated for the same abutment teeth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 3 zirconia frameworks with Lava, iTero, and Cerec infiniDent systems. The conventional workflow included a polyether impression, manual waxing, the lost-wax technique, and the casting of a metal framework. The discrepancies between the frameworks and the abutment teeth were registered using the replica technique with polyvinyl siloxane. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using a light microscope. Post hoc t tests with Bonferroni correction were applied to detect differences (α=.05).Results
Discrepancyshoulder was 96.1 ±61.7 μm for the iTero, 106.9 ±96.0 μm for the Lava, 112.2 ±76.7 μm for the Cerec infiniDent, and 126.5 ±91.0 μm for the conventional workflow. The difference between the iTero and the conventional workflow was statistically significant (P=.029). Discrepancyocclusal was 153.5 ±66.8 μm for the iTero, 203.3 ±127.9 μm for the Lava, 179.7 ±63.1 μm for the Cerec infiniDent, and 148.8 ±66.8 μm for the conventional workflow. Discrepancyocclusal was significantly lower for the conventional workflow than for the Lava and the Cerec infindent workflows (P<.01). The iTero resulted in significantly lower values of Discrepancyocclusal than the Lava and the Cerec infiniDent workflows (P<.01).Conclusions
In terms of framework fit in the region of the shoulder, digitally fabricated zirconia 3-unit frameworks presented similar or better fit than the conventionally fabricated metal frameworks. In the occlusal regions, the conventionally fabricated metal frameworks achieved a more favorable fit than the CAD-CAM zirconia frameworks. 相似文献2.
Irena Sailer Sven Mühlemann Vincent Fehmer Christoph H.F. Hämmerle Goran I. Benic 《The Journal of prosthetic dentistry》2019,121(1):69-75
Statement of problem
Clinical trials are needed to evaluate digital and conventional technologies for providing fixed partial dentures.Purpose
The purpose of the first part of this clinical study was to test whether complete-arch digital scans were similar to or better than complete-arch conventional impressions regarding time efficiency and participant and clinician perceptions.Material and Methods
Ten participants in need of a posterior tooth-supported 3-unit fixed partial denture were included. Three intraoral digital scanners and subsequent workflows (Lava C.O.S.; 3M [Lava], iTero; Align Technology Inc [iTero], Cerec Bluecam; Dentsply Sirona [Cerec]) were compared with the conventional impression method using polyether (Permadyne; 3M) and the conventional workflow. A computer-generated randomization list was used to determine the sequence of the tested impression procedures for each participant. The time needed for the impression procedures, including the occlusal registration, was assessed. In addition, the participant and clinician perceptions of the comfort and difficulty of the impression were rated by means of visual analog scales. Data were analyzed with the nonparametric paired Wilcoxon test together with an appropriate Bonferroni correction to detect differences among the impression systems (α=.05).Results
The total time for the complete-arch impressions, including the preparation (powdering) and the occlusal registration, was shorter for the conventional impression than for the digital scans (Lava 1091 ±523 seconds, iTero 1313 ±418 seconds, Cerec 1702 ±558 seconds, conventional 658 ±181 seconds). The difference was statistically significant for 2 of the 3 digital scanners (iTero P=.001, Cerec P<.001). The clinicians preferred the conventional impression to the digital scans. Of the scanning systems, the system without the need for powdering was preferred to the systems with powdering. No impression method was clearly preferred over others by the participants.Conclusions
For complete-arch impressions, the conventional impression procedures were objectively less time consuming and subjectively preferred by both clinicians and participants over digital scan procedures. 相似文献3.
Anna Gabriella Camacho Presotto Cláudia Lopes Brilhante Bhering Marcelo Ferraz Mesquita Valentim Adelino Ricardo Barão 《The Journal of prosthetic dentistry》2017,117(3):373-379
Statement of problem
Several studies have shown the superiority of computer-assisted design and computer-assisted manufacturing (CAD-CAM) technology compared with conventional casting. However, an advanced technology exists for casting procedures (the overcasting technique), which may serve as an acceptable and affordable alternative to CAD-CAM technology for fabricating 3-unit implant-supported fixed dental prostheses (FDPs).Purpose
The purpose of this in vitro study was to evaluate, using quantitative photoelastic analysis, the effect of the prosthetic framework fabrication method (CAD-CAM and overcasting) on the marginal fit and stress transmitted to implants. The correlation between marginal fit and stress was also investigated.Material and methods
Three-unit implant-supported FDP frameworks were made using the CAD-CAM (n=10) and overcasting (n=10) methods. The frameworks were waxed to simulate a mandibular first premolar (PM region) to first molar (M region) FDP using overcast mini-abutment cylinders. The wax patterns were overcast (overcast experimental group) or scanned to obtain the frameworks (CAD-CAM control group). All frameworks were fabricated from cobalt-chromium (CoCr) alloy. The marginal fit was analyzed according to the single-screw test protocol, obtaining an average value for each region (M and PM) and each framework. The frameworks were tightened for the photoelastic model with standardized 10-Ncm torque. Stress was measured by quantitative photoelastic analysis. The results were submitted to the Student t test, 2-way ANOVA, and Pearson correlation test (α=.05).Results
The framework fabrication method (FM) and evaluation site (ES; M and PM regions) did not affect the marginal fit values (P=.559 for FM and P=.065 for ES) and stress (P=.685 for FM and P=.468 for ES) in the implant-supported system. Positive correlations between marginal fit and stress were observed (CAD-CAM: r=0.922; P<.001; overcast: r=0.908; P<.001).Conclusions
CAD-CAM and overcasting methods present similar marginal fit and stress values for 3-unit FDP frameworks. The decreased marginal fit of frameworks induces greater stress in the implant-supported system. 相似文献4.
Marco Zeltner Irena Sailer Sven Mühlemann Mutlu Özcan Christoph H.F. Hämmerle Goran I. Benic 《The Journal of prosthetic dentistry》2017,117(3):354-362
Statement of problem
Trials comparing the overall performance of digital with that of conventional workflows in restorative dentistry are needed.Purpose
The purpose of the third part of a series of investigations was to test whether the marginal and internal fit of monolithic crowns fabricated with fully digital workflows differed from that of crowns fabricated with the conventional workflow.Material and methods
In each of 10 participants, 5 monolithic lithium disilicate crowns were fabricated for the same abutment tooth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 4 crowns using the Lava, iTero, Cerec inLab, and Cerec infinident systems. The conventional workflow included a polyvinyl siloxane impression, manual waxing, and heat-press technique. The discrepancy between the crown and the tooth was registered using the replica technique with polyvinyl siloxane material. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using light microscopy. Post hoc Student t test with Bonferroni correction was applied to detect differences (α=.05).Results
Discrepancymarginal was 83.6 ±51.1 μm for the Cerec infinident, 90.4 ±66.1 μm for the conventional, 94.3 ±58.3 μm for the Lava, 127.8 ±58.3 μm for the iTero, and 141.5 ±106.2 μm for the Cerec inLab workflow. The differences between the treatment modalities were not statistically significant (P>.05). Discrepancyshoulder was 82.2 ±42.4 μm for the Cerec infinident, 97.2 ±63.8 μm for the conventional, 103.4 ±52.0 μm for the Lava, 133.5 ±73.0 μm for the iTero, and 140.0 ±86.6 μm for the Cerec inLab workflow. Only the differences between the Cerec infinident and the Cerec inLab were statistically significant (P=.036). The conventionally fabricated crowns revealed significantly lower values in Discrepancycusp and Discrepancyocclusal than all the crowns fabricated with digital workflows (P<.05).Conclusions
In terms of marginal crown fit, no significant differences were found between the conventional and digital workflows for the fabrication of monolithic lithium disilicate crowns. In the occlusal regions, the conventionally manufactured crowns revealed better fit than the digitally fabricated crowns. Chairside milling resulted in less favorable crown fit than centralized milling production. 相似文献5.
Amir Reza Hendi Mohammad Moharrami Hakimeh Siadat Habib Hajmiragha Marzieh Alikhasi 《The Journal of prosthetic dentistry》2019,121(2):364.e1-364.e6
Statement of problem
Conventional cast metal posts and cores are fabricated using direct and indirect techniques, both of which need impression materials and considerable laboratory work. Digital techniques have the capacity to substitute for conventional methods in fabricating the posts and cores. However, the accuracy of restorations resulting from a digital workflow is unknown.Purpose
The purpose of this in vitro study was to compare the retention of posts and cores fabricated using full-digital, half-digital, and conventional techniques and to define the accuracy of each technique in terms of the apical gap.Method and materials
Thirty newly extracted mandibular first and second premolar teeth were selected for this in vitro study. Impressions were made using direct acrylic resin patterns (conventional), indirect silicone impressions of the intracanal which scanned with a 3Shape laboratory scanner (half digital), and intracanal scan posts captured with an intraoral 3Shape scanner (full digital). Casting and milling were conducted for the conventional impression and digital scans. The obtained posts were cemented using zinc phosphate cement. A universal pullout test was used to measure retention at a crosshead speed of 0.5 mm/min. The apical gap of each post in the canals was defined with parallel digital radiography. The data were analyzed using the Kruskal-Wallis test (α=.05) and Mann-Whitney test at the adjusted α=.016.Results
Significant differences were found among the conventional, full-digital, and half-digital techniques in terms of the apical gap (0.11, 0.29, and 0.66 mm; P<.001) and retention (171.6 ±1.9, 107.1 ±5.6 and 91.8 ±6.6 N; P<.001). The correlation between gap and retention in conventional (P=.43), full-digital (P=.09), and half-digital techniques (P=.06) was not statistically significantly different.Conclusions
The conventional technique was more accurate and resulted in higher retention than both the full- and half-digital techniques. However, the retention and gap of all the posts fell within clinical guidelines. 相似文献6.
Nicole Kalberer Albert Mehl Martin Schimmel Frauke Müller Murali Srinivasan 《The Journal of prosthetic dentistry》2019,121(4):637-643
Statement of problem
Complete dentures fabricated by computer-aided design and computer-aided manufacturing (CAD-CAM) techniques have become popular. The 2 principal CAD-CAM techniques, milling and rapid prototyping (3D printing), used in the fabrication of complete dentures have been reported to yield clinically acceptable results. However, clinical trials or in vitro studies that evaluated the accuracy of the 2 manufacturing techniques are lacking.Purpose
The purpose of this in vitro study was to compare the differences in trueness between the CAD-CAM milled and 3D-printed complete dentures.Material and methods
Two groups of identical maxillary complete dentures were fabricated. A 3D-printed denture group (3DPD) (n=10) and a milled denture group (MDG) (n=10) from a reference maxillary edentulous model. The intaglio surfaces of the fabricated complete dentures were scanned at baseline using a laboratory scanner. The complete dentures were then immersed in an artificial saliva solution for a period of 21 days, followed by a second scan (after immersion in saliva). A third scan (after the wet-dry cycle) was then made after 21 days, during which the complete dentures were maintained in the artificial saliva solution during the day and stored dry at night. A purpose-built 3D comparison software program was used to analyze the differences in the trueness of the complete dentures. The analyses were performed for the entire intaglio surface and specific regions of interest: posterior crest, palatal vault, posterior palatal seal area, tuberosity, anterior ridge, vestibular flange, and mid-palatal raphae. Independent t tests, ANOVA, and post hoc tests were used for statistical analyses (α=.05).Results
The trueness of the milled prostheses was significantly better than that of the rapid prototyping group with regard to the entire intaglio surface (P<.001), posterior crest (P<.001), palatal vault (P<.001), posterior palatal seal area (P<.001), tuberosity (P<.001), anterior ridge (baseline: P<.001; after immersion in saliva: P=.001; after the wet-dry cycle: P=.011), vestibular flange (P<.001), and mid-palatal raphae (P<.001).Conclusions
The CAD-CAM, milled complete dentures, under the present manufacturing standards, were superior to the rapidly prototyped complete dentures in terms of trueness of the intaglio surfaces. However, further research is needed on the biomechanical, clinical, and patient-centered outcome measures to determine the true superiority of one technique over the other with regard to fabricating complete dentures by CAD-CAM techniques. 相似文献7.
Statement of problem
Hot-pressing and computer-aided design and computer-aided manufacturing (CAD-CAM) are major techniques for the fabrication of lithium disilicate crowns. They exhibit different accuracies regarding marginal fit, an important factor in restoration survival. However, studies comparing the marginal fit of different fabrication methods are lacking.Purpose
The purpose of this in vitro study was to compare the marginal discrepancy (MD) and absolute marginal discrepancy (AMD) of lithium disilicate crowns produced by the hot-press and CAD-CAM techniques.Material and Methods
Thirty typodont teeth were divided into 2 groups. Fifteen teeth were scanned with the CEREC Omnicam intraoral scanner, and crowns were fabricated with the CEREC MC XL chairside CAD-CAM milling unit from IPS e.max CAD blocks. Fifteen typodont teeth were sent to a dental laboratory, and lithium disilicate crowns were fabricated from IPS e.max press ingots using the hot-press technique. The 30 crowns were cemented and then sectioned with a precision saw. The MD and AMD were measured for each crown with a light microscope. One-way ANOVA was conducted to analyze significant differences in crown marginal fit between the fabrication systems (α=.05).Results
For the CAD-CAM technique, the mean values of the AMD measurements were 115 μm, and for the hot-press technique, 130 μm. The MD measurements were 87 μm for the CAD-CAM technique and 90 μm for the hot-press technique. One-way ANOVA revealed no significant differences between the fabrication methods regarding marginal fit (P>.05).Conclusions
No significant differences were found between the fabrication methods tested. Both the CAD-CAM and hot-press techniques for producing monolithic lithium disilicate crowns produced MD values of less than 120 μm, within the clinically acceptable range. 相似文献8.
Bjørn Einar Dahl Hans Jacob Rønold Jon E. Dahl 《The Journal of prosthetic dentistry》2017,117(3):400-404
Statement of problem
Whether single crowns produced by computer-aided design and computer-aided manufacturing (CAD-CAM) have an internal fit comparable to crowns made by lost-wax metal casting technique is unknown.Purpose
The purpose of this in vitro study was to compare the internal fit of single crowns produced with the lost-wax and metal casting technique with that of single crowns produced with the CAD-CAM technique.Material and methods
The internal fit of 5 groups of single crowns produced with the CAD-CAM technique was compared with that of single crowns produced in cobalt-chromium with the conventional lost-wax and metal casting technique. Comparison was performed using the triple-scan protocol; scans of the master model, the crown on the master model, and the intaglio of the crown were superimposed and analyzed with computer software. The 5 groups were milled presintered zirconia, milled hot isostatic pressed zirconia, milled lithium disilicate, milled cobalt-chromium, and laser-sintered cobalt-chromium.Results
The cement space in both the mesiodistal and buccopalatal directions was statistically smaller (P<.05) for crowns made by the conventional lost-wax and metal casting technique compared with that of crowns produced by the CAD-CAM technique.Conclusions
Single crowns made using the conventional lost-wax and metal casting technique have better internal fit than crowns produced using the CAD-CAM technique. 相似文献9.
Majed Al-Akhali Matthias Kern Adham Elsayed Abdulaziz Samran Mohamed Sad Chaar 《The Journal of prosthetic dentistry》2019,121(4):644-650
Statement of problem
With the development of new computer-aided design and computer-aided manufacturing (CAD-CAM) restorative dental materials, limited data regarding their survival rate and fracture strength are available when they are used as occlusal veneers. Therefore, these materials should be evaluated under conditions similar to those of the oral environment before being recommended for clinical use.Purpose
To evaluate the influence of thermomechanical fatigue loading on the fracture strength of minimally invasive occlusal veneer restorations fabricated from different CAD-CAM materials and bonded to human maxillary premolars using self-etchnig bonding technique.Material and methods
Sixty-four CAD-CAM occlusal veneer restorations were fabricated from group LD (lithium disilicate [e.max CAD]), LS (zirconia-reinforced lithium silicate [Vita Suprinity]), PI (polymer-infiltrated ceramic [Vita Enamic]), and PM (polymethylmethacrylate [Telio CAD]). The occlusal veneers were luted to enamel (n=16) using a self-etching primer (Multilink Primer A/B) and a luting composite resin (Multilink Automix). Half of the specimens of each group (n=8) were randomly selected and subjected to thermomechanical fatigue loading in a masticatory simulator (1.2 million cycles at 98 N with 5°C-55°C thermocycling). All specimens were quasistatically loaded until fracture. The statistical analysis was made using the Kruskal-Wallis and Mann-Whitney U tests (α=.05).Results
According to the Kaplan-Meier analysis after the thermomechanical fatigue of the 4 groups, the cumulative survival rate was as follows: group LD, 50% group LS, 62.5% group PI, 37.5%; and group PM, 50%. Although some of the surviving specimens exhibited microcracking, their integrity or bonding to teeth was not affected. Thermomechanical fatigue significantly reduced the fracture strength of group PI (P=.047) and group PM (P=.025). Without thermomechanical fatigue, group PM showed significantly higher fracture strength than group LS (P=.015).Conclusions
In general, thermomechanical fatigue decreased the survival rate and fracture strength in all test groups. 相似文献10.
Statement of problem
Dental laboratories use different computer-aided design and computer-aided manufacturing (CAD-CAM) systems to fabricate fixed prostheses; however, limited evidence is available concerning which system provides the best marginal discrepancy.Purpose
The purpose of this in vitro study was to evaluate the marginal fit of 5 different monolithic zirconia restorations milled with different CAD-CAM systems.Material and methods
Thirty monolithic zirconia crowns were fabricated on a custom-designed stainless steel die and were divided into 5 groups according to the type of monolithic zirconia crown and the CAD-CAM system used: group TZ, milled with an MCXL milling machine; group CZ, translucent zirconia milled with a motion milling machine; group ZZ, zirconia milled with a dental milling unit; group PZ, translucent zirconia milled with a zirconia milling unit; and group BZ, solid zirconia milled using an S1 VHF milling machine. The marginal fit was measured with a binocular microscope at an original magnification of ×100. The results were tabulated and statistically analyzed with 1-way ANOVA and post hoc surface range test, and pairwise multiple comparisons were made using Bonferroni correction (α=.05).Results
The type of CAD-CAM used affected the marginal fit of the monolithic restoration. The mean (±SD) highest marginal discrepancy was recorded in group TZI at 39.3 ±2.3 μm, while the least mean marginal discrepancy was recorded in group IZ (22.8 ±8.9 μm). The Bonferroni post hoc test showed that group TZI was significantly different from all other groups tested (P<.05).Conclusions
Within the limitation of this in vitro study, all tested CAD-CAM systems produced monolithic zirconia restorations with clinically acceptable marginal discrepancies; however, the CAD-CAM system with the 5-axis milling unit produced the best marginal fit. 相似文献11.
Alex Leo Sequeira Aparna I. Narayan Vinu Thomas George 《The Journal of prosthetic dentistry》2019,121(5):843-847
Statement of problem
Variation in the baseline mechanical properties of polyamide thermoplastic polymers used in the fabrication of prosthetic dental appliances and the effects of nonaldehyde disinfectants on the mechanical properties of these polymers are unclear.Purpose
The purpose of this in vitro study was to compare the flexural and impact strengths of 2 flexible denture materials (Valplast and Sunflex) and evaluate the effect of 24-hour immersion in nonaldehyde disinfectant (Perform) on their flexural and impact strengths.Material and methods
Of 48 specimens of Valplast and Sunflex, half were immersed in nonaldehyde disinfectant solution containing the active ingredient 2% peroxymonosulfate for 24 hours. Flexural and impact strengths were measured using a universal testing machine. The Student t test with Bonferroni correction was used (α=.008).Results
For the Valplast group, the mean ±standard deviation flexural strength was 27.8 ±0.57 MPa, and the impact strength was 3.5 ±0.98 kJ/m2. For the Sunflex group, the mean flexural strength was 57.4 ±4.09 MPa, and the impact strength was 6.0 ±3.11 kJ/m2. Sunflex showed greater flexural strength (P≤.001) and impact strength (P=.001) than Valplast. A significant increase in the impact strength (P≤.001) but not in the flexural strength of Valplast was observed after exposure to the disinfectant solution. Immersion disinfection had no significant effect on the strength of Sunflex.Conclusions
The flexural and impact strengths of Sunflex were significantly greater than those of Valplast. Immersion disinfection with peroxymonosulfate had no significant effect on Sunflex but increased the impact strength of Valplast. 相似文献12.
Statement of problem
Selective laser melting (SLM) has become popular in prosthetic dentistry. However, only limited information is available for the internal adaptation of cobalt-chromium (Co-Cr) posts fabricated by SLM.Purpose
The purpose of this in vitro study was to investigate the internal adaptation of Co-Cr metal posts fabricated by SLM technique.Material and methods
Thirty-six Co-Cr metal posts were fabricated by conventional casting, subtractive computer-aided design and computer-aided manufacturing (CAD-CAM), and additive CAD-CAM, by making an impression from a standardized model of a tooth with a single root canal. Posts and the dies were bonded with cement. Specimens were then sectioned horizontally by using a grinding and polishing machine, and 3 different cross-sections of each post were chosen to represent the apical, middle, and coronal regions. The areas of cement were photographed by using a stereomicroscope at an original magnification of ×32 and measured using image-measuring software. From each group, 1 specimen was randomly selected and observed by using scanning electron microscopy. One-way ANOVA and Tukey honestly significant difference test were performed to identify differences among groups with regard to internal adaptation (α=.05).Result
The internal adaptation of the SLM group did not differ from that of the CAD-CAM milling group at 3 cross-section levels (P>.05). At the apical and coronal cross-section levels, the cement area of SLM group was smaller than that of the cast group (P<.05). However, at the middle cross-section level, the cement area of the cast group was significantly smaller than that of the SLM group (P<.05). Use of scanning electron microscopy showed both the SLM group and the CAD-CAM milling group exhibited homogeneous microstructures. However, the cast group showed a typical discontinuous dendritic solidification microstructure.Conclusions
The internal adaptation of SLM was not inferior to that of the CAD-CAM milling group or the cast group. The SLM technique seems a promising choice for fabricating dental posts. 相似文献13.
Lauren Bernard Marjolein Vercruyssen Julie Vanderveken Wim Coucke Marc Quirynen Ignace Naert 《The Journal of prosthetic dentistry》2019,121(2):258-264
Statement of problem
Implant-based prosthetic solutions can be time consuming. If implants can be loaded immediately, treatment time can be reduced.Purpose
The purpose of this prospective randomized controlled trial was to monitor the survival rate of Ankylos implants, comparing conventional with immediate loading by using abutments with the SynCone concept for screw-retained removable prostheses in the edentulous maxilla.Material and methods
A total of 90 implants were placed in 15 study participants. The participants were randomly assigned to the immediate or conventional loading treatment group. Radiographic and clinical parameters were recorded at the time of permanent prosthesis installment and at 1- and 2-year follow-up examinations, and participants’ satisfaction was measured by using questionnaires before and after prosthesis installation. A linear mixed model was used to measure differences.Results
One implant in the conventional group was lost during abutment placement; hence, 89 implants could be followed for 2 years. Approximately 90% of these implants showed no bone loss or even bone gain at 1 and 2 years follow-up. Mean values for the immediate group were, respectively, 0.09 ±0.35 mm and 0.13 ±0.38 mm and 0.01 ±0.41 mm and ?0.06 ±0.32 mm for the conventional method. No significant differences (P=.053) were found in bone level alterations between the groups. For all participants, the mean number of surfaces (4 per implant) with bleeding on probing (BoP) and plaque were 0.76 ±0.81 and 0.16 ±0.42 at 1 year follow-up and 0.44 ±0.66 and 0.02 ±0.15, respectively, at the second-year follow-up. The mean pocket probing depths were 2.05 ±0.54 mm at 1 year and 2.18 ±0.64 mm at 2 years. For both groups, a significant rise in satisfaction and quality of life was observed (P≤.001) at 1 and 2 years compared with pretreatment.Conclusions
Ankylos implants placed in the edentulous maxilla, immediately or conventionally loaded by a detachable prosthesis, showed favorable bone-level preservation after 2 years of follow-up. No significant differences could be found between the immediate and conventional groups. A significant increase in quality of life was observed for both loading modes. 相似文献14.
Marcela G. Borges Carlos J. Soares Thaís S. Maia Aline A. Bicalho Tarsis P. Barbosa Henara L. Costa Murilo S. Menezes 《The Journal of prosthetic dentistry》2019,121(5):868.e1-868.e8
Statement of problem
Posterior composite restorations may be negatively affected by acidic and colored drinks. Little information is available about the effect of acidic drinks on bulk-fill composite resins.Purpose
The purpose of this in vitro study was to investigate the effect of acidic drinks on the different properties of conventional and bulk-fill composite resins.Material and methods
A conventional composite resin and 2 representative bulk-fill composite resins were used to prepare disk-shaped specimens. The degree of conversion (DC) was monitored by spectroscopy (n=5). The specimens were divided into 5 groups: control, artificial saliva, acai juice, red wine, and Coca-Cola and were maintained for 30 days of challenge (3 periods of 15 min/d). Surface topography parameters were measured by interferometry (n=5). Elastic modulus (E) and Vickers hardness (VH) were determined by microhardness dynamic indentation (n=5). Diametral tensile strength (DTS) was determined at 0.5 mm/min (n=5). Shade matching was evaluated by using the Vitapan Classic Shade Guide. The DC, Sa, Ssk, Sku, Sdq, and DTS were statistically analyzed using 2-way ANOVA, followed by the Tukey HSD tests. E and VH were statistically analyzed by 3-way ANOVA, followed by Tukey HSD tests (α=.05). Shade matching was analyzed with the Kruskal-Wallis test.Results
DC values were similar for the immediate evaluation and after 24 hours, regardless of the composite resin (P<.05). All surface topography parameters increased significantly after the acidic drinks and were greatest for Coca-Cola. The E, VH, and DTS decreased significantly for all composite resins tested (P<.05). Acai juice and red wine produced more surface staining than Coca-Cola.Conclusions
Acidic drinks negatively influenced the physical and mechanical properties of conventional and bulk-fill composite resins. 相似文献15.
Marginal and internal fit of metal copings fabricated with rapid prototyping and conventional waxing
Ehsan Farjood Mahroo Vojdani Kiyanoosh Torabi Amir Ali Reza Khaledi 《The Journal of prosthetic dentistry》2017,117(1):164-170
Statement of problem
Given the limitations of conventional waxing, computer-aided design and computer-aided manufacturing (CAD-CAM) technologies have been developed as alternative methods of making patterns.Purpose
The purpose of this in vitro study was to compare the marginal and internal fit of metal copings derived from wax patterns fabricated by rapid prototyping (RP) to those created by the conventional handmade technique.Material and methods
Twenty-four standardized brass dies were milled and divided into 2 groups (n=12) according to the wax pattern fabrication method. The CAD-RP group was assigned to the experimental group, and the conventional group to the control group. The cross-sectional technique was used to assess the marginal and internal discrepancies at 15 points on the master die by using a digital microscope. An independent t test was used for statistical analysis (α=.01).Results
The CAD-RP group had a total mean (±SD) for absolute marginal discrepancy of 117.1 (±11.5) μm and a mean marginal discrepancy of 89.8 (±8.3) μm. The conventional group had an absolute marginal discrepancy 88.1 (±10.7) μm and a mean marginal discrepancy of 69.5 (±15.6) μm. The overall mean (±SD) of the total internal discrepancy, separately calculated as the axial internal discrepancy and occlusal internal discrepancy, was 95.9 (±8.0) μm for the CAD-RP group and 76.9 (±10.2) μm for the conventional group. The independent t test results showed significant differences between the 2 groups. The CAD-RP group had larger discrepancies at all measured areas than the conventional group, which was statistically significant (P<.01).Conclusions
Within the limitations of this in vitro study, the conventional method of wax pattern fabrication produced copings with better marginal and internal fit than the CAD-RP method. However, the marginal and internal fit for both groups were within clinically acceptable ranges. 相似文献16.
Mohamed H. Helal Hebatullah D. Hendawy Rowan A. Gaber Nourhan R. Helal Moustafa N. Aboushelib 《The Journal of prosthetic dentistry》2019,121(1):118-123
Statement of problem
Reconstruction of alveolar bony defects is difficult using grafting materials in a powder form. A biodegradable scaffold material might simplify the procedure.Purpose
The purpose of this in vivo study was to evaluate osteogenesis ability of a biodegradable CAD-CAM–fabricated polylactic acid (PLA) scaffold enriched with calcium phosphate salts including hydroxyapatite (HA) and beta tricalcium phosphate (β-TCP) used to reconstruct mandibular defects in a dog model.Material and Methods
Surgical defects were made bilaterally in the mandible of male beagle dogs. Computerized tomography images were obtained for determination of the 3-dimensional shape of the defects after 3 months of healing. Porous PLA scaffolds were fabricated by milling custom-made CAD-CAM blocks into the desired shape. After milling, half of the scaffolds were prepared by filling the pores of the scaffolds by a mixture of HA and β-TCP. Scaffolds were inserted in the mandibular defects bilaterally. After a healing time of 8 weeks, the bone-scaffold interface was analyzed histomorphometrically to detect the amount of new bone formation. Stained histological sections were examined using a computer software and depth of new bone formation was assessed (n=14, α=.05).Results
Histomorphometric analysis revealed that enriched scaffolds with calcium phosphates had significantly (t=4.4, P<.001) higher amounts of new bone formation (1.3 ±0.33 mm) compared with the controls (0.7 ±0.39 mm). Average new bone growth in enriched scaffolds was 1.3 mm while almost half this value was observed in uncoated scaffolds, 0.7 mm.Conclusions
Within the limitations of this animal study, HA and β-TCP enhanced osteogenesis ability of CAD-CAM–fabricated PLA scaffolds. 相似文献17.
Weina Wang Hai Yu Yifan Liu Xinlei Jiang Bo Gao 《The Journal of prosthetic dentistry》2019,121(2):285-291
Statement of problem
The primary manufacturing method of zirconia ceramic crowns is computer-aided design and computer-aided manufacture (CAD-CAM), but a disadvantage of this technique is material waste. Three-dimensional (3D) printing, which has been recently introduced into dentistry, has improved the processing of polymers and metals, but not yet of ceramic crowns.Purpose
The purpose of this in vitro study was to evaluate the 3D trueness of zirconia crowns fabricated by 3D printing to investigate the potential application of this technology in dental ceramic restorations.Material and methods
A typodont tooth was prepared for a ceramic crown, and a digital crown was designed using the CAD software. The digital crown was processed either with a 3D-printing system or with a dental milling system. The crowns were scanned using a dental laboratory scanner, and the data collected for each crown were divided into 4 parts (the external surface, intaglio surface, marginal area, and intaglio occlusal surface). Finally, the trueness of each part was determined using the 3D inspection software. The 3D trueness of the crowns fabricated by either 3D printing or milling was compared by a 1-sided test (α=.05).Results
The trueness of the external surface, intaglio surface, marginal area, and intaglio occlusal surface of the 3D-printed crowns was no worse than the corresponding trueness of the CAD-CAM crowns (P<.05).Conclusions
Zirconia crowns produced by 3D printing meet the trueness requirements, and 3D printing may be suitable for fabricating zirconia crowns. 相似文献18.
Statement of problem
Well-balanced physical properties of computer-aided design and computer-aided manufacturing (CAD-CAM) materials are important to ensure the clinical success and longevity of restorations. Therefore, the capacity of a material to dissipate destructive fracture energy by means of elastic and plastic material deformation is of interest. However, little information is available on how to quantify the resilience and toughness of CAD-CAM materials.Purpose
The purpose of this in vitro study was to investigate and compare the resilience and toughness of CAD-CAM restorative materials and assess their capability to dissipate destructive fracture energy in comparison with a high–gold-content alloy.Material and methods
Restorative materials for 3-unit fixed partial dentures (Alphador No. 1, IPS e.max CAD, Lava Plus, PEEK Optima), crowns and onlays (CERASMART, CEREC Blocs, Lava Ultimate, VITA ENAMIC), and interim prostheses (M-PM Disc, Telio CAD) were investigated. The strain energy density was determined with a 3-point bend test to calculate the modulus of toughness, the modulus of resilience, and the elastic recovery and thus characterize the material properties of resilience and toughness. Data were statistically analyzed with a generalized linear mixed model by using the Huber-White sandwich estimator (α=.05).Results
Significant differences were found among the materials concerning the modulus of toughness, the modulus of resilience, the elastic recovery, and the difference between the elastic recovery and the modulus of resilience (P<.001). Alphador produced the highest mean regarding the modulus of toughness followed by Telio CAD, Lava Plus, M-PM Disc, CERASMART, and Lava Ultimate; all showed significantly higher capacities to dissipate energy by elastic and plastic deformation when compared with the ceramic materials (IPS e.max CAD, VITA ENAMIC, CEREC Blocs). For the modulus of resilience and elastic recovery, Lava Plus and Alphador showed the highest mean values and therefore better able to only elastically absorb destructive fracture energy; the least able materials were VITA ENAMIC and CEREC Blocs. As PEEK Optima, M-PM Disc, and Lava Ultimate showed higher mean values for the modulus of resilience than IPS e.max CAD, they were better able to elastically dissipate energy.Conclusions
Alphador had the highest values for the modulus of toughness, the elastic recovery, and the difference between the elastic recovery and the modulus of resilience; this was equivalent to pronounced energy dissipation capacities. In comparison, Lava Plus showed the highest modulus of resilience but significantly lower results for all other parameters and therefore fewer energy-consuming capabilities. The new polymer-based CAD-CAM restorative materials in general had a higher modulus of toughness and elastic recovery than ceramics and thereby partially resemble Lava Plus, all with similar capacities to dissipate destructive energy. 相似文献19.
Christin Arnold Jeremias Hey Ramona Schweyen Jürgen M. Setz 《The Journal of prosthetic dentistry》2018,119(4):586-592
Statement of problem
The conventional fabrication of removable partial dentures (RPDs) is a complex, error-prone, time-consuming, and expensive process. The use of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, especially rapid prototyping, promises a more effective method for fabricating RPD frameworks.Purpose
The purpose of this in vitro study was to evaluate the fit of RPD clasps fabricated by means of 4 different CAD-CAM-systems and to compare those fittings with that of the conventional lost-wax casting technique (LWT).Material and methods
A master model of a partially edentulous maxilla with the canines and second molars as the remaining teeth was fabricated. After the model was optically scanned, we designed a quadrangularly supported RPD with 4 clasps and a palatal strap major connector. A standard tessellation language data set was used to fabricate 12 identical RPDs by using 4 different CAD-CAM techniques: indirect rapid prototyping (wax inject printing combined with LWT), direct rapid prototyping (selective laser melting), indirect milling (wax milling with LWT), and direct milling (resin milling [polyetheretherketone]). Three conventionally cast RPDs (LWT) served as the control group. The fit accuracy of the clasps (n=12 for each group) was determined in both the horizontal and vertical dimensions by using light microscopy.Results
Indirectly milled RPDs (117 ±34 μm horizontal and 45 ±21 μm vertical) and directly milled RPDs (43 ±23 μm horizontal, and 38 ±21 μm vertical) showed significantly better (P<.05) fit than did conventionally fabricated LWT RPDs (133 ±59 μm horizontal; 73 ±25 μm vertical). The worst fit was found for RPDs fabricated using indirect rapid prototyping (323 ±188 μm horizontal and 112 ±60 μm vertical) or direct rapid prototyping (365 ±205 μm horizontal and 363 ±133 μm vertical), which were unstable on the master model, making them unsuitable for clinical use. Most RPDs exhibited smaller vertical measuring distances.Conclusions
Compared with the LWT, milling techniques enabled fabrication of RPDs with comparable or better fit. However, RPDs fabricated with rapid prototyping techniques showed distinct fitting irregularities. 相似文献20.
Joshua A. Manchester Kwok-Hung Chung James S. Brudvik Van Ramos Yen-Wei Chen 《The Journal of prosthetic dentistry》2019,121(5):828-835