Mean Gap Values Research Articles

INFLUENCE OF CERAMIC MATERIALS AND PREPARATION DESIGNS ON THE MARGINAL ADAPTATION OF INLAYS AND ONLAYS AFTER THERMOCYCLING.

To evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intracoronal preparation designs. An examination of the marginal adaptation of two materials-lithium disilicate (LD; IPS e.max CAD) and polymer infiltrated ceramic network material (PICN; Vita Enamic)-and two preparation designs, where D1 represents MOD inlay preparation with no cusp reduction and for D2, in addition to the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. Four sub-groups (LD-D1, LD-D2, PICN-D1, PICN-D2) were conducted. In total, 40 (n = 40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, SD, minimum, maximum, and 95% CI. Pairwise comparisons using Tukey post-hoc test were performed following an ANOVA significance of P ≤ .05. The results revealed that lithium disilicate showed statistically significantly higher mean gap distance than PICN material (61 μm to 99 μm). Pairwise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Both LD and PICN material provided marginal adaptation within clinical accepted range. PICN material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional preparation.

In Vitro Evaluation of marginal adaptation of polyether ether ketone and zirconia copings.

Polyether ether ketone (PEEK) has emerged as a new thermoplastic material with potential applications as a restorative material. Aim: This study aimed to evaluate the marginal adaptation of PEEK copings compared to zirconia copings using field emission scanning electron microscopy. A freshly extracted maxillary central incisor was prepared for a full-coverage restoration following standard principles of tooth preparation. The tooth was sent to a laboratory for fabrication of samples using computer-aided design and manufacturing (CAD/CAM). Twenty samples of polyether ether ketone (PEEK) copings (group A) and 20 of zirconia copings were fabricated (group B). The copings were scanned under a field emission scanning electron microscope and measurements were taken at four distinct points. The marginal adaptation over the buccal, lingual, mesial, and distal margins for both groups was evaluated. One-way analysis of variance (ANOVA) and independent t test were applied. Our findings indicate that PEEK showed better marginal adaptation than zirconia at all measurement points. The mean marginal gap value of the PEEK group was 33.99 ± 8.81 μm and of the zirconia group was 56.21 ± 15.07 μm. On comparing marginal adaptation among the mesial, distal, buccal, and lingual aspects, PEEK showed better adaptation on all four margins, with the best adaptation on the buccal margin that had the lowest mean gap value of 29.27 ± 6.07 μm. The zirconia group adapted best at the distal margin, with a lowest mean gap value of 53.58 ± 15.25 μm (P ≤ 0.05). PEEK copings had better marginal adaptation and fit compared to zirconia copings. It may have applications as a restorative material in fixed prostheses.

Micro-CT analysis of marginal and internal fit of milled and pressed polyetheretherketone single crowns

Statement of problemPolyetheretherketone (PEEK) has been increasingly used as a framework material in prosthetic dentistry. However, data on the marginal and internal fit of PEEK restorations fabricated by using either the computer-aided design and computer-aided manufacturing (CAD-CAM) or heat-pressing technique are sparse. PurposeThe aim of this in vitro study was to assess the marginal and internal fit of milled and pressed PEEK single crowns by using microcomputed tomography (μCT). Material and methodsA custom-made, single stainless-steel die was designed to replicate a maxillary first premolar prepared for a ceramic crown. PEEK copings (N=30) were fabricated and allocated to 3 groups (n=10) according to the fabrication technique: milled from a prefabricated PEEK blank, heat pressed from PEEK pellets, and heat pressed from PEEK granules. All copings were veneered with a composite resin material. The marginal fit was recorded at 4 predetermined points and the internal fit at 8 predetermined points on each crown by using μCT. Two-way ANOVA, pair-wise Tukey honestly significant difference (HSD), and simple main effect tests were used for statistical analysis of the data (α=.05). ResultsConcerning marginal fit, the milled crowns demonstrated the best marginal fit overall (44 ±3 μm), followed by those pressed from pellets (92 ±3 μm), and finally by those pressed from granules (137 ±7 μm) (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the marginal fit was not statistically significant (P=.142). The milled crowns demonstrated the lowest mean gap values overall, followed by those pressed from pellets and those pressed from granules (P<.001). The interaction between the effects of the fabrication technique and the measurement point on the internal fit was statistically significant (P<.001). Except for the distal occlusal gap and mesial occlusal gap, all tested groups showed a statistically significant difference (P<.001). In addition, statistically significant differences were observed among all measurement points in different fabrication techniques (P<.001). ConclusionsThe marginal and internal fit of milled PEEK crowns was significantly better than pressed crowns. However, both CAD-CAM and heat-pressing techniques produced PEEK crowns with a clinically acceptable marginal and internal fit. The mean marginal gap of the PEEK crowns pressed from granules was above the range of clinically acceptable value.

Fit analysis of stereolithography-manufactured three-unit resin prosthesis with different 3D-printing build orientations and layer thicknesses

Statement of problemPrinting conditions can affect the fit of a 3-dimensionally (3D) printed prosthesis. Therefore, it is important to determine the optimal printing conditions for stereolithography (SLA)-manufactured prostheses. PurposeThe purpose of this study was to analyze the fit according to the build orientations and layer thicknesses in SLA-manufactured 3-unit resin prostheses. Material and methodsSLA 3D printed prostheses were produced in 5 build orientations (0, 30, 45, 60, and 90 degrees) and 2 layer thicknesses (50 and 100 μm). Milled prostheses were fabricated from the same design. The mounted prostheses on the master model were scanned with microcomputed tomography (μCT). Data were processed with the NRecon software program. For quantitative analysis, marginal and internal fits were measured by using the imageJ software program in terms of the following metrics: absolute marginal discrepancy, marginal gap, cervical area, midaxial wall area, line-angle area, and occlusal area. Internal gap volume was also measured with the CTAn software program. For statistical analysis, ANOVA and Tukey HSD tests were used (α=.05). For qualitative analysis, μCT cross-sections were compared among groups, and intaglio surfaces were imaged with a scanning electron microscope. ResultsA layer thickness of 50 μm with build orientations of 45 and 60 degrees exhibited smaller mean gap values (P<.05) than the other conditions for all measurements except line-angle area and occlusal area. The scanning electron microscope images showed voids on the intaglio surfaces for the 0- and 90-degree groups. ConclusionsFor SLA 3D printed resin prostheses, a difference in fit occurred based on the printing conditions, although both 3D printed and milled prostheses showed a clinically acceptable fit. When an SLA 3D printed prosthesis is manufactured under appropriate conditions, a clinically acceptable fit can be obtained.

Marginal and Internal Fit of Monolithic Zirconia Crowns Fabricated by Using Two Different CAD-CAM Workflows: An In Vitro Study

Objectives: Few studies have evaluated the marginal fit of computer-aided design—computer-aided manufacturing (CAD-CAM) monolithic zirconia crowns fabricated through completely digital workflow; however, the internal fit of these restorations is not well known. The purpose of this in vitro study was to evaluate the marginal and internal fit of monolithic zirconia crowns fabricated by using digital workflow, including intraoral scanner (IOS) scans, and compare the results to those of a semi-digital workflow, which combined conventional impressions, poured casts, and extraoral scanner (EOS) scanning. Materials and methods: A typodont right mandibular first molar was prepared for a complete-coverage ceramic crown and scanned using an IOS. The conventional impressions of the preparation were also made, and stone casts were poured and scanned by using an EOS. Virtual models were generated for both workflows, and identical virtual anatomic contour crowns were designed using CAD software. Monolithic zirconia crowns were fabricated for both IOS (ZI; n = 10) and EOS (ZE; n = 10) groups. The silicon replica technique was used to evaluate the marginal and internal fit of the crowns. Measurements were made at 13 points on buccolingual and mesiodistal cross-sections per specimen with a ×6.5 to ×50 zoom stereo microscope. The results from both groups were statistically compared using the Independent Samples t-tests and the Mann–Whitney U test (α = 0.05). Results: Mean gap values at all measurement locations for ZE were significantly higher than those for ZI (p ≤ 0.002). Overall mean values ranged between 29 and 43 µm (median: 28–42 µm) for ZI and 42 and 75 µm (median: 43–77 µm) for ZE. Conclusion: Completely digital workflow through intraoral scans provided significantly better marginal and internal fit for CAD-CAM monolithic zirconia crowns compared with the semi-digital workflow, where stone casts obtained from conventional impressions were scanned with an EOS. Yet, both workflows provided an acceptable marginal and internal fit for CAD-CAM monolithic zirconia molar crowns (&lt;120 µm). Clinical Relevance: Completely digital workflow using IOS scans may be advantageous for the fabrication of CAD-CAM monolithic zirconia crowns as favorable results can be obtained with less material waste and potentially shortened overall treatment time as the impression files can be transferred to the production facility electronically. The results need to be corroborated with clinical studies.

Optimization of Fraud Potential Prevention in Implementation of National Health Insurance at Puskesmas Abeli

Fraud actions at institutions can catapult health costs. Globally, the potential loss due to fraud is estimated at 7,29% every year. Increasing the number of referrals in advanced health facilities FKTL is an indication of fraud behavior. In Southeast Sulawesi, the referral rate is high, reaching 17% with the maximum ideal standard for the average referral rate of first level health facilities(FKTP) to advanced health facilities(FKTL), not more than 5%. While in Kendari City in 2015, the referral rate from Puskesmas to Abunawas General Hospital was also still high at around 9.5% in 2015 and an increase of 15.3% in 2016. One of the puskesmas that provided referrals was Abeli ​​Community Health Center. This study aims to analyze the potential for fraud prevention in the implementation of National health insurance(JKN) at Abeli ​​Health Center. This study using observational analytic using one group pre test and post test design. Research was conducted at Abeli ​​Health Center and technique used was cluster random sampling with 28 respondents. From the statatistic test results obtained, there were differences in knowledge before and after the intervention with a mean gap value of 0, 21429 with a lower limit of 0.05226 and an upper limit of 37631 and a p value&lt;α (0.011 &lt;0.05). The suggestion in this study is to the health centers and hospitals to increase more understanding of fraud in the implementation of the JKN program by having socialization.

Impact of speed sintering on marginal discrepancy, internal fit and microleakage of monolithic zirconia crowns with different chamfer width

Purpose: The current in-vitro investigation analyzed the impact of speed sintering and different finish line width on marginal adaptation, internal fit and microleakage of translucent monolithic zirconia crowns.Materials and Methods: Sixty maxillary premolars were reduced based on basic guidelines of tooth preparation for a zirconia crown with either 0.5, 0.8 and 1.2 mm chamfer width (n=20each finish line width). After digital scanning and milling of zirconia crowns, the sintering procedure was performed in special furnace for two different sintering programs (n =10 per group) following either standard or speed sintering procedure. Each crown was cemented to its corresponding prepared tooth utilizing self-adhesive-resin cement. After 15000 thermal cycles between 5°C and 55°C, specimens were submersed in methylene blue for 12 hours. After sectioning bucco-lingually, marginal gap and cement film thickness values were recorded at nine sites using a digital microscope followed by microleakage scores examination.Results: Tested groups with 0.5 mm chamfer widths had the greatest mean marginal gap values of 47.9±5.4 and 50.1±5.6 µm for both conventional and speed sintering respectively, while groups with 1.2 chamfer widths had the lowest mean gap values of 42.3±5.6 and 44.5±5 µm for both standard and speed sintering, respectively. Two-way ANOVA revealed statically insignificant impact of sintering procedure on crown adaptation (p=.08). The greatest mean microleakage score (3±088 µm) was obtained from the 0.5 mm chamfer width group, while the smallest (2±0.78 µm) score was obtained from the 1.2 mm chamfer width group. Conclusions: Marginal adaptation and internal fit of translucent monolithic zirconia crowns are affected by width of the preparation margin while sintering protocol has little impact on adaptation.

Clinical and Laboratory Evaluation of the Fit Accuracy of Metal Frameworks of Removable Partial Denture Fabricated from Two Different Pattern Materials

Objective: The purpose behind this conducted study was clinical and laboratory assessments of the fit accuracies of cobaltchromium frameworks for removable partial dentures fabricated by traditional lost wax technique (TT), and the Light Cure Modeling Material Technique (LCMT). Materials and Methods: Sixteen healthy male Kennedy class I patients were selected from the specialty clinics in the Faculty of Dentistry, Taif University. The patients were divided into two Groups eight patients each; Group I: their metallic framework was constructed from the traditional lost wax patterns technique (TT), Group II: their metallic framework was fabricated by Light Cure Modeling Material Technique (LCMT). Conventional clinical and laboratory steps for construction of metallic partial denture were followed. The frameworks resulted from the two pattern materials were tested clinically and laboratory for fit accuracies and the results were statistically analyzed using the two-tailed t-tests. Results: Clinical results show an appropriate thickness of the impression materials and improved fit accuracy of the Light cure group in comparison to the traditional wax pattern group. Laboratory findings also showed that the Light cure group has significantly smaller mean gap values than the traditional wax pattern group. Conclusions: The fit accuracies of cobalt-chromium frameworks of removable partial denture fabricated from LCMT are better than that fabricated from TT.

A Comparative Gap Analysis Study using Stereomicroscopy between Screw Retained Zirconia Frameworks, TILOP Selective Laser Sintering Frameworks and Conventional Cast Metal Frameworks

Background: The target of this in vitro study was to compare and analyze the gap between abutment finish lines and implant analogues using stereomicroscope between three different screw retained frameworks; Zirconia Frameworks, TILOP45 Selective Laser Sintering Frameworks and Conventional Cast Metal Frameworks Materials and Methods: This In-vitro study involved the construction of a total of eight models. Three screw-retained frameworks were constructed on each model hence creating three groups; Group A, B and C. For Group A: Screw-retained frameworks were constructed using the conventional cast metal technology as For Group B: Screw-retained zirconium frameworks were constructed using the CAD/CAM technology and finally For Group C: Screw-retained frameworks were constructed using the Selective Laser sintering SLS technology TILOP 45 (TILOP = Titanium Low Oxygen Powder). Final frameworks of each group were screwed over each model and then using stereomicroscope, a gap analysis was performed.Results: When comparing the mean gap values of the three groups, the study has shown that there was a statistically significant difference in the mean gap values between both the Zirconia and TILOP45 frameworks and the conventional cast frameworks (p<0.001). The highest mean gap Value was found in conventional cast frameworks while the least mean gap value was found in the Zirconia frameworks. Results also revealed that there was no statistically significant difference in the mean gap values between the Zirconia Frameworks and the TILOP45 Selective Laser Sintering Frameworks.Conclusion: Within the limitations of this study, it can be concluded that selective laser sintering technology as well as the CAD/CAM Zirconia technology renders more passive frameworks than the conventional cast method. There seems to be a very close similarity between the accuracy of frameworks constructed with the selective laser sintering technology and the CAD/CAM Zirconia technology.

Fit accuracy of metal partial removable dental prosthesis frameworks fabricated by traditional or light curing modeling material technique: An in vitro study

ObjectiveThe aim of this study was to compare the fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks fabricated by the traditional technique (TT) or the light-curing modeling material technique (LCMT).Materials and methodsA metal model of a Kennedy class III modification 1 mandibular dental arch with two edentulous spaces of different spans, short and long, was used for the study. Thirty identical working casts were used to produce 15 PRDP frameworks each by TT and by LCMT. Every framework was transferred to a metal master cast to measure the gap between the metal base of the framework and the crest of the alveolar ridge of the cast. Gaps were measured at three points on each side by a USB digital intraoral camera at ×16.5 magnification. Images were transferred to a graphics editing program. A single examiner performed all measurements. The two-tailed t-test was performed at the 5% significance level.ResultsThe mean gap value was significantly smaller in the LCMT group compared to the TT group. The mean value of the short edentulous span was significantly smaller than that of the long edentulous span in the LCMT group, whereas the opposite result was obtained in the TT group.ConclusionWithin the limitations of this study, it can be concluded that the fit of the LCMT-fabricated frameworks was better than the fit of the TT-fabricated frameworks. The framework fit can differ according to the span of the edentate ridge and the fabrication technique for the metal framework.

Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (α = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 μm) were significantly higher than for DC-Zircon (75.3 ± 13.2 μm) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 μm) and MDP-RC (78.5 ± 12.5 μm) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC.

Effect of anatomic, semi-anatomic and non-anatomic occlusal surface tooth preparations on the adaptation of zirconia copings.

PURPOSETo compare the accuracy of marginal and internal adaptation of zirconia (Zr) copings fabricated on anatomic (A), semi-anatomic (SA) and non-anatomic (NA) occlusal surface preparations.MATERIALS AND METHODS45 extracted bicuspid teeth were prepared for receiving zirconia crowns, with different occlusal preparation designs A=15, SA=15 & NA=15. The Zr copings were fabricated by using CAD4DENT, CAD/CAM. The copings were adjusted, cemented and were cross sectioned centrally from buccal cusp tip to lingual cusp tip into mesial and distal halves. The copings were examined under electron microscope at ×200 magnification and the measurements were recorded at 9 predetermined areas in micrometers.RESULTSOverall mean gap values for the three groups was found to be 155.93±33.98 µm with Anatomical Occlusal preparation design having the least gap value of 139.23±30.85 µm showing the best adaptation among the groups. Post Hoc Tukey's test showed a statistically significant difference (P=.007) between the means of gap for A & NA preparation designs. Measurements recorded at 9 predetermined points showed variations for the three groups.CONCLUSIONAnatomical occlusal preparation designs resulted in better marginal and internal adaptation of Zr copings. There is a considerable variation between the measured marginal and internal gap values for the Zr copings fabricated by the (CAD4DENT-CAD/CAM). This variation may be associated with the lack of standardization of the preparation of teeth, computerized designing of the coping for each tooth, cement used, uniform pressure application during the cementation of the copings, sectioning of the copings and the microscopic measurements.

Adaptation of all-ceramic fixed partial dentures

Objectives To measure the marginal and internal fit of three-unit fixed partial dentures (FPDs) using the micro-CT technique, testing the null hypothesis that there is no difference in the adaptation between the ceramic systems studied. Methods Stainless steel models of prepared abutments were fabricated to design the FPDs. Ten FPDs were produced from each framework ceramic (YZ – Vita In-Ceram YZ and IZ – Vita In-Ceram Zirconia) using CEREC inLab according to the manufacturer instructions. All FPDs were veneered using the recommended porcelain. Each FPD was seated on the original model and scanned using micro-CT. Files were processed using NRecon and CTAn software. Adobe Photoshop and Image J software were used to analyze the cross-sections images. Five measuring locations were used as follows: MG – marginal gap; CA – chamfer area; AW – axial wall; AOT – axio-occlusal transition area; OA – occlusal area. The horizontal marginal discrepancy (HMD) was evaluated in another set of images. Results were statistically analyzed using ANOVA and Tukey tests ( α = 0.05). Results The mean values for MG, CA, AW, OA and HMD were significantly different for all tested groups ( p < 0.05). IZ exhibited greater mean values than YZ for all measuring locations except for AW and AOT. OA showed the greatest mean gap values for both ceramic systems. MG and AW mean gap values were low for both systems. Significance The ceramic systems evaluated showed different levels of marginal and internal fit, rejecting the study hypothesis. Yet, both ceramic systems showed clinically acceptable marginal and internal fit.

Evaluation of marginal adaptation of ceramic crowns depending on the marginal design and the addition of ceramic

This study evaluates the marginal adaptation of ceramic copings front of two finish lines and addition of ceramic. Hence, two master steel dies were milled with all-ceramic crowns preparation, one with a round shoulder finish line margin design, and the other with a deep chamfer. From each one of them, 15 copings were made, and the marginal discrepancy was evaluated in measuring microscope. The ceramic addition was accomplished in both groups with aid of a silicone matrix, and the discrepancies were measured again, obtaining the final mean gap values. The initial measurements resulted means of 44,0µm for deep chamfer and 24,0µm for the round shoulder, and the final measurements were 53,3µm for the deep chamfer and 27,4µm for the round shoulder. The data were submitted to the analysis of variance for verification of influence of the finish lines and application of the ceramic. When analyzed the interaction among the variables it was not observed statistical differences, but when comparing the two types of finish lines or the groups before and after ceramic addition, statistical differences were found. It is was concluded that the round shoulder finish line presents better values of marginal gap than deep chamfer and the addition of ceramic influences in the final gap values of marginal adaptation.

Marginal adaptation of a sintered ceramic inlay system before and after cementation

summary The long term clinical performance of porcelain inlays depends on a number of factors and the marginal adaptation is one of significant interest. The purpose of this in vitro study was to evaluate the marginal integrity of a sintered inlay technique (Ducera®), before and after cementation. MOD cavities without bevels were prepared on 10 human mandibular molar teeth and porcelain inlays were fabricated according to the manufacturer's instructions. Inlays were evaluated microscopically for their adaptation to the occlusal and approximal margins of the tooth by means of a replica technique. Inlays were cemented with a dual‐cured bybrid composite luting material (Enforce®). After polishing, each tooth was sectioned in buccal/lingual and mesial/distal directions following the same procedure in the sectioning of replicas. The marginal gap and the thickness of exposed cement were measured at each section. The mean marginal gap of 71.83 ± 8.93 μm recorded for the occlusal margin before cementation was significantly smaller than that of 1056 ± 39.33 μm calculated at the approximal margin. Following the cementation, the adaptation of the inlays at the occlusal margin was also found to be superior to that of the approximal margin. Comparison of mean gap values before and after cementation revealed that the marginal gap increased by 6.94 μm and 23.25 μm at the occlusal and approximal margins, respectively. Although polishing was performed after cementation, excess luting material was still observed, that caused an increase in the width of the exposed luting cement.

NIOSH equation horizontal distances associated with the Liberty Mutual (Snook) lifting table box widths

A study was conducted to determine the NIOSH equation horizontal distances (d H) associated with the three different box widths (34, 49 and 75 cm) and lift starting heights (floor, knuckle and shoulder) used in the psychophysically based Liberty Mutual lifting tables (Snook 1978, Snook and Ciriello 1991). Data were collected with 12 male and 12 female subjects and three repetitions were performed for each of the nine lifting conditions. No gender effects were observed so male and female data were pooled. The value of d H was positively related to box width but there was also a significant interaction between box width and starting height. When pooled across lift heights the average values of d H were 44, 49 and 57 cm for the 34, 49 and 75 cm box widths, respectively. When pooled across box widths the average values of d H were 52, 45 and 52 cm for the floor, knuckle and shoulder height lifts, respectively. A knowledge of the d H associated with each box width will allow for direct comparisons to be made between the NIOSH and Liberty Mutual outputs. This will facilitate further validation of the NIOSH equations. A variable (GAP) was calculated to indicate the horizontal distance from the ankles to the edge of the box. Previously, this GAP has been assumed to remain constant and values of 15, 20 and 25 cm have been proposed. The GAP was observed to have an overall mean of 23·6 cm with individual condition means ranging from 14·6 cm to 31·2 cm. When pooled across conditions the mean GAP values were equal to d H minus half the box width.