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

Abstract

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.

Fabrication of crown restoration retrofitting to existing clasps using CAD/CAM: Fitness accuracy and retentive force

“…In one technique, a lost wax procedure is carried out for metal restorations, but there are still many problems. Since all laboratory processes are manually completed, the quality of the prosthesis is affected by the skill of the dental technicians [9][10][11]. It is difficult to give appropriate ideal contours, undercuts, rest seats, and guiding planes to the new retrofitted crowns using the conventional lost wax technique.…”

A Validation Study of the Impression Replica Technique

“…The material properties of all luting cements used for FDPs in dentistry allow cement thickness below 25 μm . As mentioned in the introduction, no standard gap value exists, and the clinically acceptable gap varies between 30 and 120 μm . A gap smaller than 80 μm is hard to detect with a regular probe .…”

“…27 As mentioned in the introduction, no standard gap value exists, and the clinically acceptable gap varies between 30 and 120 µm. 11,13,14,[17][18][19] A gap smaller than 80 µm is hard to detect with a regular probe. 18 Some authors also suggest that the silicone corresponds well to zinc phosphate cement.…”

“…11 Several studies have investigated marginal fit and proposed a measurement of a clinically acceptable fit [10][11][12][13][14][15][16] varying from 30 to 120 µm. 11,13,14,[17][18][19] Various methods are described in the literature for measuring the fit/misfit of a restoration. The impression replica technique is a frequently used method because it can be performed both in vivo and in vitro.…”

Evaluation of Internal and Marginal Fit of Two Metal Ceramic System – In Vitro Study

“…All copings were cemented to respective dies using zinc phosphate cement under finger pressure and standardized sectioning of the copings were made and internal and marginal discrepancies were measured under stereomicroscope [20]. The results were tabulated.…”