Preparation design and margin distortion in porcelain-fused-to-metal restorations

Shillingburg, Herbert T.; Hobo, Sumiya; Fisher, Donald

doi:10.1016/0022-3913(73)90007-3

Cited by 145 publications

(57 citation statements)

References 9 publications

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“…Different finish-line designs have been advocated for several reasons. Preston3 and Shillingburg4 recommended the shoulder-bevel as the best type of finish line for the cast restoration. Rosner5 reasoned that a beveled finish line would fit better than a shoulder and trigonometric analysis to support his assertion.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard

Rastogi

Kamble

2011

J Adv Prosthodont

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PURPOSEThis study assessed the effect of preparation design on marginal adaptation and also compared the sensitivity and specificity of clinical evaluation techniques for marginal accuracy of cast restorations to stereomicroscopy.MATERIALS AND METHODSThree Ivorine molar teeth of different designs were prepared. (A)-A complete crown preparation with buccal shoulder and beveled finish line. (B)-A complete crown preparation with chamfer finish line. (C)-A three-quarter crown preparation with proximal boxes and beveled finish line. Twenty four castings were prepared with eight castings for each design respectively. Each casting underwent examination with an explorer, disclosing media, and a stereomicroscope. Stereomicroscopy at a value less than or equal to 30 microns was used as a gold standard to evaluate the significance of different designs on marginal adaptation. Chi-square tests of independence and Kruskal-Wallis were used to evaluate the effect of preparation design and compare the agreement between examination methods for detection of marginal gap size of greater than or equal to 30 microns (α=.05). Sensitivity and specificity for explorer and disclosing media as compared to stereomicroscope was calculated using statistical formula given by Park.RESULTSThe preparation design did not significantly affect overall marginal adaptation. Examination by explorer and disclosing media at 30 µm revealed 39% and 10.06% sensitivity and 91% and 82% specificity respectively.CONCLUSIONPreparation designs examined in this study did not significantly affect the marginal adaptation of the castings. Commonly used clinical evaluation techniques using explorer and disclosing media appeared to be inadequate for assessment of marginal accuracy.

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Section: Introductionmentioning

confidence: 99%

Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard

Rastogi

Kamble

2011

J Adv Prosthodont

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“…Few studies have investigated this problem. Investigators have attributed this issue to reduced metal collar thickness,4 thermal coefficient mismatch, margin design,5 and margin spee 6. Whatever the cause of the distortion, the mismatch of the restoration-abutment complex has to be corrected because an unacceptable marginal gap could result in cement washout,12 with subsequent biological complications, such as secondary caries, periodontal problems and pulpitis 13,14…”

Section: Discussionmentioning

confidence: 99%

“…In metal-porcelain restorations, corruption of the initial fit of the metal framework has been reported after the porcelain firing cycle and observed clinically as a marginal discrepancy 4,5,6. Gemalmaz and Alkumru7 attributed marginal discrepancies to porcelain-metal thermal contraction mismatch, the design of the margin, and the type of alloy used.…”

Section: Introductionmentioning

confidence: 99%

Effects of metal surface grinding at the porcelain try-in stage of fixed dental prostheses

et al. 2014

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PURPOSEThis study was to evaluate the effect of grinding of the inner metal surface during the porcelain try-in stage on metal-porcelain bonding considering the maximum temperature and the vibration of samples.MATERIALS AND METHODSNinety-one square prism-shaped (1 × 1 × 1.5 mm) nickel-chrome cast frameworks 0.3 mm thick were prepared. Porcelain was applied on two opposite outer axial surfaces of the frameworks. The grinding was performed from the opposite axial sides of the inner metal surfaces with a low-speed handpiece with two types of burs (diamond, tungsten-carbide) under three grinding forces (3.5 N, 7 N, 14 N) and at two durations (5 seconds, 10 seconds). The shear bond strength (SBS) test was performed with universal testing machine. Statistical analyzes were performed at 5% significance level.RESULTSThe samples subjected to grinding under 3.5 N showed higher SBS values than those exposed to grinding under 7 N and 14 N (P<.05). SBS values of none of the groups differed from those of the control group (P>.05). The types of bur (P=.965) and the duration (P=.679) did not affect the SBS values. On the other hand, type of bur, force applied, and duration of the grinding affected the maximum temperatures of the samples, whereas the maximum vibration was affected only by the type of bur (P<.05).CONCLUSIONGrinding the inner metal surface did not affect the metal-porcelain bond strength. Although the grinding affected the maximum temperature and the vibration values of the samples, these did not influence the bonding strength.

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“…Because of high variation of the values within same crown system, the mean value of all measurement locations can show a large local discrepancy and result in an increase in Standard Deviation (SD) 28,41. Although the SD in such studies has been reported to be approximately 20 µm 10,14,16,17,20,33-37. In-Ceram crowns shows mean marginal gap of 27.5 µm14 in one study and 123 µm44 in another.…”

Section: Introductionmentioning

confidence: 93%

“…Direct viewing is a nondestructive and convenient method and has been most frequently used to measure marginal gap at various stages of manufacturing process. Various means of measuring marginal gap by direct viewing include Stereomicroscope,14-17 optical microscope,18-20 optical microscope with image analyzing software,21-23 Laser microscope,24 Scanning Electron Microscope25-27 etc. There are various other non-destructive methods reported in the literature like profile projector28 and laser videography 29.…”

Section: Introductionmentioning

confidence: 99%

A comparison of marginal fit of glass infiltrated alumina copings fabricated using two different techniques and the effect of firing cycles over them

Bhowmik

Parkhedkar

2011

J Adv Prosthodont

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PURPOSEThis study evaluated marginal fit of glass infiltrated alumina cores fabricated using two techniques and their marginal stability after firing cycles of veneering porcelain.MATERIALS AND METHODSFifteen standardized all-ceramic crowns were fabricated on a metal die using each technique: slip cast technique of VITA In-Ceram sprint Alumina (Group A as control) and plastic foil matrix technique of Turkom-Cera fused alumina core system (Group B). Copings were compared between groups and within groups at coping stage and after firing each layer of veneering porcelain. A device was used to standardize seating of copings on the metal die and positioning of the specimens under the microscope after each stage of fabrication. The specimens were not cemented and marginal gap was measured using an image analyzing software (Imagepro Express) on the photographs captured under an optical microscope. Two tailed unpaired 't test' was used to compare marginal gaps in two groups and one way ANOVA was used to analyze marginal distortion within each group at 95% confidence interval.RESULTSThe marginal gap was smaller at the coping stage in group B (60 + 30 µm) than group A (81 + 21 µm) with statistical significance. After firing of veneering porcelain the difference was insignificant. At the final stage, both groups exhibited lower mean marginal gaps than at the initial coping stage with the difference of 11.75 µm for group A and 11.94 µm for group B, but it was statistically insignificant due to high value of standard deviation.CONCLUSIONWithin the limitations of this study, it was concluded that both techniques produced copings with comparable and acceptable marginal fit and marginal stability on firing veneering porcelain.

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Preparation design and margin distortion in porcelain-fused-to-metal restorations

Cited by 145 publications

References 9 publications

Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard

Comparative analysis of the clinical techniques used in evaluation of marginal accuracy of cast restoration using stereomicroscopy as gold standard

Effects of metal surface grinding at the porcelain try-in stage of fixed dental prostheses

A comparison of marginal fit of glass infiltrated alumina copings fabricated using two different techniques and the effect of firing cycles over them

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