Tag: statistics

Int J Prosthodont. 2022 Sep 15. doi: 10.11607/ijp.8177. Online ahead of print.

ABSTRACT

PURPOSE: To assess stress and deformation in telescopic removable partial denture (RPD) frameworks manufactured with polyether ether ketone (PEEK) or graphene-modified polymethyl methacrylate (PMMA), as well as the stress of the underlying mucosa, via nonlinear 3D finite element analysis.

MATERIALS AND METHODS: The 3D model of a full mandible was merged with a 3D-scanned Kennedy Class I model with bilaterally missing molars. The tissues, the telescopic crowns, and the RPD framework were designed and created using dental CAD software. The model was duplicated, and two materials-PEEK and graphene-modified PMMA-were assigned to the telescopic crowns and their frameworks. A force of 200 N was applied perpendicularly to the molars, and constraints were placed in the mandibular ramus and the inferior border. The generated von Mises stress and deformation of the frameworks, as well as the stresses of the telescopic crowns and mucosa, were also assessed. Statistical analysis of the differences between the tested materials was conducted via an independent samples t test at (α = .05).

RESULTS: The von Mises stresses of the telescopic crowns and their frameworks in the graphene-modified PMMA model were significantly higher than in the PEEK model. In contrast, the deformation of the telescopic RPD framework of the PEEK model was significantly higher than the graphene-modified PMMA model. The stresses of the mucosa in both models showed an insignificant difference.

CONCLUSION: PEEK material showed better biomechanical performance than the graphene-modified PMMA in telescopic RPDs.

PMID:36125879 | DOI:10.11607/ijp.8177

Int J Prosthodont. 2022 Jul-Aug;35(4):545-552. doi: 10.11607/ijp.7563.

ABSTRACT

PURPOSE: To evaluate the shear bond strength (SBS) of different digital veneering techniques for zirconia and to critically discuss its suitability for application in single-implant prosthetics.

MATERIALS AND METHODS: A total of 112 square-shaped zirconia specimens were provided with four different veneering materials (n = 28 per group): a glass-ceramic (group GLA), a feldspathic ceramic (group FEL), a polymer-infiltrated ceramic network (group PIC), and a resin nanoceramic (group RNC). Discs in group GLA were sintered onto the core material, whereas all other specimens were adhesively connected. In each group, 14 specimens (GLA0, FEL0, PIC0, RNC0) were subjected to SBS testing before thermocycling, and the other 14 (GLA1, FEL1, PIC1, RNC1) were tested after thermocycling (10,000 cycles). Data were analyzed by applying SPSS software (P < .05). The surfaces and fracture patterns of the specimens were examined using scanning electron microscopy (SEM).

RESULTS: Mean SBS values ranged from 14.09 ± 3.87 MPa (RNC1) to 40.82 ± 4.91 MPa (GLA0). Group GLA presented higher values than all other groups (P < .001). Groups FEL, PIC, and RNC showed no statistically significant differences between them. SBS decreased after thermocycling, but no significant impact was found. Every group exhibited a characteristic failure mode.

CONCLUSION: All digital veneering techniques sufficed to present clinically acceptable SBS values and might be viable alternatives in implant prosthetics. However, some have yet to demonstrate their long-term clinical suitability. At present, lithium disilicate-veneered zirconia abutments and monolithic lithium disilicate hybrid abutment crowns seem to present a proven and reliable restorative option.

PMID:36125877 | DOI:10.11607/ijp.7563

Int J Prosthodont. 2022 Jul-Aug;35(4):494-501. doi: 10.11607/ijp.8060.

ABSTRACT

PURPOSE: To investigate the precementation mean marginal gap, fracture resistance, and mode of failure of monolithic zirconia endocrowns cemented to endodontically treated molar teeth with butt joint porcelain margins and added ferrule preparation designs.

MATERIALS AND METHODS: A total of 20 mandibular molars were endodontically treated and prepared to receive endocrown restorations. The teeth were randomly divided into two groups: Group B had a butt joint porcelain margin, while Group F received additional axial reduction with a shoulder finish line that added ferrule. Monolithic zirconia endocrowns were milled, and the marginal gaps were measured at four locations prior to cementation with resin cement. All samples were subjected to thermocycling, followed by compressive static loading. The maximum load causing fracture and mode of failure were recorded.

RESULTS: The mean load to failure for Group B (5,616 ± 1,503 N) was not significantly different compared to Group F (5,762 ± 1,618 N) (P = .84). Both groups recorded high rates of irreparable fractures (P = .2699, df = 2). The mean marginal gap in Group B (48.20 ± 12.37 μm) was not statistically significantly different compared to Group F (45.14 ± 8.45 μm) (P = .527).

CONCLUSION: The addition of ferrule to the preparation design had no significant effect on the precementation mean marginal gap, fracture resistance, or mode of failure of monolithic zirconia endocrowns cemented to endodontically treated molar teeth. Monolithic zirconia endocrowns failed predominantly in an irreparable manner, but these failures were at high failure loads. The precementation mean marginal gap for both groups was small in comparison to other materials.

PMID:36125874 | DOI:10.11607/ijp.8060

Int J Prosthodont. 2022 Jul-Aug;35(4):487-493. doi: 10.11607/ijp.8010.

ABSTRACT

PURPOSE: To evaluate the effect of different cavity designs and cement types on the fracture resistance of monolithic zirconia inlay-retained fixed dental prostheses (IRFDPs).

MATERIALS AND METHODS: Four study models consisting of a second premolar, a missing first molar, and a second molar were used for the different cavity designs. Four different inlay cavity designs were prepared: DO-MO (disto-occlusal-mesio-occlusal cavity), MOD-MOD (mesio-occlusodistal-mesio-occlusodistal cavity), WDO-WMO (DO-MO with additional wings), and WMOD-WMOD (MOD-MOD with additional wings). A total of 64 epoxy resin models were produced and scanned individually. IRFDPs were then fabricated from monolithic zirconia using CAD/ CAM software. The bonding surface of the IRFDPs was airborne particle abraded (50-μm alumina/2 MPa), then cemented onto the epoxy resin models using two cementation protocols (n = 8 per group): (1) P = cemented with Panavia SA Cement Plus Automix; and (2) Z/C = cemented with MDP-containing primer (Z-Prime Plus) combined with Calibra Universal resin cement. All IRFDPs were fatigued through thermal aging (6,000 cycles/5°C to 55°C) and chewing simulations (600,000 cycles × 50-N load, 2.1 Hz). All IRFDPs were then subjected to a fracture resistance test using a universal testing machine with a crosshead speed of 0.2 mm/minute. Data were statistically analyzed using one- and two-way ANOVA and Bonferroni multiple comparisons test (P = .001).

RESULTS: The mean fracture load (N) of the designs were as follows: WMODWMOD = 1,111.1; WDO-WMO = 1,057.4; MOD-MOD = 725.6; DO-MO = 682.7. According to two-way ANOVA, the differences among the cavity designs were statistically significant (P < .05).

CONCLUSION: The cavity design of IRFDPs affected the fracture resistance. However, the fracture resistance of monolithic zirconia IRFDPs with any cavity design was enough to withstand expected posterior chewing forces.

PMID:36125873 | DOI:10.11607/ijp.8010

Int J Prosthodont. 2022 Jul-Aug;35(4):469-479. doi: 10.11607/ijp.7551.

ABSTRACT

PURPOSE: To evaluate the biaxial flexural strength of different porcelain-to-zirconia thickness ratios and bonding strategies of a stress-free bilayer CAD/CAM ceramic system.

MATERIALS AND METHODS: A total of 60 zirconia discs (diameter: 15 mm; thickness: 0.3 or 0.5 mm; n = 30 for each thickness) were divided into six groups (n = 10 each) according to porcelain-to-zirconia ratio and bonding strategy: VM/Zr (control): zirconia discs veneered with a feldspathic ceramic (VM 9, Vita) in 0.9-mm and 0.7-mm thicknesses using a conventional hand-layering technique; VB/Zr-SBU: zirconia discs airborne particle-abraded with 50-μm Al₂O₃ particles followed by an MDP primer application (Single Bond Universal, 3M) and bonded to the porcelain with a resin cement (Panavia F 2.0, Kuraray); and VB/Zr-RC: zirconia discs airborne particle-abraded with 30-μm silica-coated Al₂O₃ particles and silanized and bonded to the porcelain with the same resin cement. Before cementation, the VB (Vitablocs II) discs were etched with 5% hydrofluoric acid (60 seconds), followed by silane application. The bilayers (thickness = 1.2 mm) were loaded with 750 g while light curing the resin cement. Two porcelain-to-zirconia thickness ratios were evaluated: 0.9: 0.3 mm and 0.7: 0.5 mm. All groups were subjected to 106 mechanical cycles, followed by a biaxial flexural test. Data (MPa) were subjected to two-way analysis of variance (ANOVA), Tukey test (5%), and Weibull analyses.

RESULTS: Two-way ANOVA revealed that the factor porcelain-to-zirconia ratio (P = .0556) was not significant; however, the bonding strategy factor was statistically significant. Among the 0.5-mm zirconia groups, the VB/Zr-SBU group presented higher flexural strength (s) than the VM/Zr or VB/Zr-RC groups. Similar results were also found for the 0.3-mm zirconia groups, in which the VB/Zr-SBU group also presented higher strength than the others, which were similar in comparison (Tukey). The Weibull modulus was similar among the groups; however, the characteristic strength was significantly different (P = .000).

CONCLUSION: The zirconia bonding strategy with 50-μm Al²O³ airborne-particle abrasion, followed by a primer application, increases the flexural strength of a stress-free bilayer CAD/CAM ceramic system.

PMID:36125871 | DOI:10.11607/ijp.7551

Int J Prosthodont. 2022 Jul-Aug;35(4):460-468. doi: 10.11607/ijp.7703.

ABSTRACT

PURPOSE: To evaluate the effect of different luting techniques on the shear bond strength (SBS) of ultra-translucent multi-layered zirconia (UTML) after 24 hours and 1 year of water storage and to analyze the influence of primers on the wettability of the UTML MTU-6 surface.

MATERIALS AND METHODS: Four commercial resin cements were evaluated: Variolink Esthetic LC (Ivoclar Vivadent); RelyX Ultimate (3M); Estecem II (Tokuyama); and Panavia V5 (Kuraray Noritake). Panavia V5 was tested with and without Panavia V5 Tooth Primer (Kuraray Noritake). The SBS immediately after cement/primer application and after aging, scanning electron microscopy of the surfaces, and the contact angle of the primers on the UTML surfaces were analyzed.

RESULTS: At 24 hours, Panavia V5 with Tooth Primer exhibited the highest SBS. After 1 year, the SBS of Variolink Esthetic LC and Panavia V5 with Tooth Primer decreased, and RelyX Ultimate increased. There was no statistical difference between RelyX Ultimate and Panavia V5 with Tooth Primer at 1 year. For all groups, the rate of adhesive failures increased after 1 year. The highest contact angle was observed on the control (no primer) group, and the lowest contact angles were obtained when the YSZ surface was treated with Scotchbond Universal and the combination of Clearfil Ceramic Primer Plus and Tooth Primer.

CONCLUSION: Clinicians should prefer 10-MDP-based cementation systems that can be properly polymerized to achieve a stable long-term bond strength to YSZ restorations. Also, the use of ceramic primers improves the capability of the cement to establish an intimate contact with the intaglio of the restoration.

PMID:36125870 | DOI:10.11607/ijp.7703

Int J Prosthodont. 2022 Jul-Aug;35(4):453-459. doi: 10.11607/ijp.7177.

ABSTRACT

PURPOSE: To evaluate the retention of zirconia crowns on polyetheretherketone (PEEK) abutments using different luting agents, with and without PEEK primer.

MATERIALS AND METHODS: A total of 100 PEEK abutment replicas were fabricated, airborne particle-abraded with aluminum oxide, and divided into four groups (n = 25). A total of 100 zirconia crowns were fabricated and cemented using either adhesive resin cement or self-adhesive resin cement with and without PEEK primer; thus, the groups were: group AA-P (adhesive cement with primer); group AA-N (adhesive cement without primer); group SA-P (self-adhesive cement with primer); and group SA-N (self-adhesive cement without primer). The specimens were thermocycled and subjected to crown pull-out tests. The values were recorded and analyzed using analysis of variance and post hoc analysis (α = .05). The mode of failure of debonded surfaces was evaluated using scanning electron microscopy.

RESULTS: The pull-out force values were 3.13 ± 0.31 MPa for group AA-P, 1.77 ± 0.20 MPa for group AA-N, 2.10 ± 0.12 MPa for group SA-P, and 1.49 ± 0.18 MPa for group SA-N. Statistically significant differences were found between all four groups (P < .001). The specimens with PEEK primer applied showed higher values compared to nonprimed specimens for both cements tested. Scanning electron microscopy analysis showed more mixed failures for adhesive cement and more adhesive failures for self-adhesive resin cement.

CONCLUSION: The maximum pull-out forces were recorded for zirconia crowns bonded to PEEK abutments with adhesive cement. The use of PEEK primer increased the pull-out values for both resin cements.

PMID:36125869 | DOI:10.11607/ijp.7177

Int J Prosthodont. 2022 Jul-Aug;35(4):396-404. doi: 10.11607/ijp.8032.

ABSTRACT

PURPOSE: To compare the esthetic outcomes of anterior implant-supported single crowns as evaluated by patients and clinicians of different specialties.

MATERIALS AND METHODS: A total of 133 patients with 138 implant-supported crowns were recalled from the National Dental Centre Singapore Implant Registry to rate the esthetic outcomes of their restorations using a visual analog scale (VAS) questionnaire. Patients with crowns in the maxillary or mandibular canine-to-canine region with a contralateral natural tooth and minimum time in function of 6 months were recruited. Three clinicians trained in prosthodontics rated each restoration using the modified Pink Esthetic Score/White Esthetic Score (PES/WES) index through photographs and models. Two periodontists, two orthodontists, and two general dentists each rated a randomized sample of 40 crowns using the same index for comparison. Statistical analysis was done using a linear mixed model, analysis of variance, intraclass correlation coefficient, kappa score, Spearman rank correlation, and Mann- Whitney U tests.

RESULTS: Mean PES, WES, and PES/WES scores for the 138 implants were 4.7, 5.0, and 9.7, respectively. Based on modified PES/WES criteria, 22 (15.9%) of the 138 implants were deemed clinically acceptable. Mean patient VAS scores ranged from 79.3 to 84.4 out of 100. Prosthodontists had significantly lower mean PES, WES, and PES/WES scores (P < .05) than the other specialties. When orthodontists were excluded, papilla scores had the highest agreement of all the variables.

CONCLUSION: Patients were less critical of esthetic outcomes than clinicians. A weak correlation was found between patients’ subjective evaluations and the modified PES/WES index as rated by prosthodontists. Prosthodontists were the strictest assessors.

PMID:36125868 | DOI:10.11607/ijp.8032

Int J Prosthodont. 2022 Jul-Aug;35(4):387-395. doi: 10.11607/ijp.7342.

ABSTRACT

PURPOSE: To compare the clinical outcomes of single implants with titanium (Ti) or zirconia (Zr) abutments after up to 5 years in function.

MATERIALS AND METHODS: This study was a retrospective analysis on single implants with screw-retained abutments (Zr or Ti) covered with porcelain veneer placed between 2011 and 2013 at one referral specialist clinic. Clinical data from patient records were collected from 132 patients and 174 implants. Technical complications such as fractures, chipping, and abutment screw loosening were registered. Radiographs were analyzed comparing both annual bone loss and accumulated bone loss at 5 years. In 57 patients with 85 implants, the values of accumulated bone loss at 5 years were compared to baseline.

RESULTS: Technical complications occurred in 16 (9%) of the implants, most often during the first year. The following complications were found: fracture of the abutment (n = 1); loosening of the abutment screws (n = 5); and chipping of the porcelain veneer (n = 11). Ti abutments had more complications than Zr abutments (79%). Of all the implants, 45% had an annual bone loss ranging between 0.05 and 2.15 mm, and 59% had an accumulated bone loss at 5 years ranging between 0.05 and 4.25 mm. Zr abutments had a statistically significantly higher amount of yearly and accumulated bone loss at 5 years.

CONCLUSION: Abutment material affected marginal bone loss. The Zr group displayed statistically more bone loss both yearly and after 5 years compared to the Ti group. Technical complications were not affected by abutment material but were affected by age of the patient.

PMID:36125867 | DOI:10.11607/ijp.7342

JMIR Mhealth Uhealth. 2022 Sep 20;10(9):e35851. doi: 10.2196/35851.

ABSTRACT

BACKGROUND: Hematological malignancies (HMs) are a heterogeneous group of cancers representing a significant cause of morbidity and mortality. The chronification of HMs and the increasing use of smartphones may lead patients to seek their current unmet needs through mobile health apps.

OBJECTIVE: The goal of this review was to identify and assess the quality of smartphone apps aimed at patients diagnosed with HMs.

METHODS: A systematic search of apps that were aimed at patients diagnosed with HMs, accessed from a Spain IP address, and were available on the iOS (App Store) and Android (Google Play) platforms was conducted in November 2021. The search terms used were “hematology,” “blood cancer,” “leukemia,” “lymphoma,” and “myeloma” apps in English, Spanish, or both languages. The identified apps were downloaded and analyzed independently by 2 reviewers. Information about general app characteristics was collected. The Mobile Application Rating Scale (MARS) was used to assess quality. The resulting parameter of the analyses, the mean score of the apps, was compared by Student t test.

RESULTS: Overall, 18 apps were identified; 7 were available on Android, 5 were available on iOS, and 6 were available on both platforms. All included apps were free; 3 were published in 2021, and among the apps published before 2021, only 6 were updated in 2021. Most (16/18, 89%) of the apps were aimed at patients with leukemia or lymphoma (16). The primary purposes of the apps were to provide general information about the condition (16/18, 89%) and monitor symptoms and clinical parameters (11/18, 61%). Health care professionals contributed to the development of 50% (9/18) of apps; 6 were owned and supported by scientific societies, and 3 were developed with the participation of health care professionals. The mean MARS score for the overall quality of the apps was 3.1 (SD 1.0). The engagement and aesthetics subscales were the lowest rated subscales, with only 44% (8/18) and 67% (12/18), respectively, of the apps obtaining acceptable scores. None of the included apps proved clinical efficacy through clinical trials in patients with HMs. Statistically significant differences were found in the MARS scores between operating systems (+1.0, P=.003) in favor of iOS apps. The participation of health care professionals in the development of the apps did not have a statistically significant impact on the MARS scores.

CONCLUSIONS: This systematic search and evaluation identified few acceptable quality mobile apps for patients with HMs. Current and future apps for patients with HMs should provide evidence-based valuable information, improve user engagement, incorporate functions according to patient preferences, and generate evidence regarding the efficacy of app use by patients with HMs.

PMID:36125860 | DOI:10.2196/35851