Comparison of the retention of the full veneer casted gold crowns with varying convergence angle, crown length and dental cements

Yun, Jung‐Ho; Cho, Jin Hyung; Kim, Jeehwan; Lee, Keun Woo

doi:10.4047/jkap.2013.51.2.99

Cited by 1 publication

(2 citation statements)

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“…Convergence angle can be defined as “the angle between opposing axial walls” and has been shown to affect crown retention. In addition, it has been demonstrated that the increase of convergence angle reduces the retentive force regardless of the type of cement [ 7 , 13 ].…”

Section: Discussionmentioning

confidence: 99%

“…Other studies also supported that finding by reporting the average convergence angle ranging from 14 to 20°, which is considerably deviated from the ideal value [ 6 , 12 ]. An increase of convergence angle results in a reduction of the average retention force regardless of the type of cement used [ 13 ]. Implant placement procedures have already reached a level of computer guidance that implements preoperative planning, surgical guiding, and uses an optical tracking device [ 4 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

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Development of a dental handpiece angle correction device

Nam

Kim

2018

BioMed Eng OnLine

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BackgroundPreparation of a uniform angle of walls is essential for making an ideal convergence angle in fixed prosthodontics. We developed a de novo detachable angle-correction apparatus for dental handpiece drills that could help the ideal tooth preparation.MethodsWe utilized a gyro sensor to measure the angular velocities to calculate the slope of an object by integrating the values, acceleration sensor to calculate the slope of an object by measuring the acceleration relative to gravity, and Kalman filter algorithm. Converting the angulation of the handpiece body to its drill part could be performed by a specific matrix formulation set on two reference points (2° and 6°). A flexible printed circuit board was used to minimize the size of the device. For convergence angle investigation, 16 volunteers were divided randomly into two groups for performing tooth preparation on a mandibular first molar resin tooth. All abutments were scanned by a 3D scanner (D700®, 3Shape Co., Japan), the convergence angle and tooth axis deviation were analyzed by a CAD program (SolidWorks 2013®, Dassault Systems Co., USA) with statistical analysis by Wilcoxon signed-rank test (α = 0.05) using SPSS statistical software (Version 16.0, SPSS Inc.).ResultsThis device successfully maintained the stable zero point (less than 1° deviation) at different angles (0°, 30°, 60°, 80°) for the first 30 min. In single tooth preparation, without this apparatus, the average bucco-lingual convergence angle was 20.26° (SD 7.85), and the average mesio–distal (MD) convergence angle was 17.88° (SD 7.64). However, the use of this apparatus improved the average BL convergence angle to 13.21° (SD 4.77) and the average MD convergence angle to 10.79° (SD 4.48). The angle correction device showed a statistically significant effect on reducing the convergence angle of both directions regardless of the order of the directions.ConclusionsThe angle correction device developed in this study is capable of guiding practitioners with high accuracy comparable to that of commercial navigation surgery. The volume of the angle correction device is much smaller than that of any other commercial navigation surgery system. This device is expected to be widely utilized in various fields of orofacial surgery.

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Section: Discussionmentioning

confidence: 99%