Assessment of convergence angles of tooth preparations for complete crowns among dental students

Ayad, Mohamed F.; Maghrabi, Abdulhamid A.; Rosenstiel, Stephen F.

doi:10.1016/j.jdent.2004.12.008

Cited by 56 publications

(63 citation statements)

References 20 publications

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“…The mean TOC found in the current study was 26.3 degrees that is slightly higher than that measured in other studies (26,27,(33)(34)(35). This disparity in the TOC values might be explained by including dies from GP in this study.…”

Section: Discussioncontrasting

confidence: 81%

Convergence Angles of Clinical Tooth Preparations for Metal Ceramic Restorations Among Dental Students and General Practitioners

Hinnara¹,

Barngkgei

Nassar³

2017

Avicenna J Dent Res

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Background: Numerous studies showed that the convergence angle (CA) of prepared teeth for fixed prosthodontics in the clinical practice is greater than the recommended values. Objectives: This cross-sectional study aimed to compare the total occlusal convergence (TOC) angles of metal ceramic fixed prosthodontics among dental students [final-year undergraduate (UG) and Master Prosthodontics (MS) students] and general practitioners (GP) in their private clinics with the recommended value (≤ 12 degrees). Methods: The buccolingual (BL) and mesiodistal (MD) TOC of 114, 90, and 111 stone dies referred to UG, MS, and GP, respectively, were measured. These dies included incisors, premolars, and molars. One sample Wilcoxon signed rank test, Mann-Whitney U test, Kruskal-Wallis, and Fisher exact test were used for statistical analysis. Results: Mean values of TOC for UG were 27.8 degrees BL and 20.9 degrees MD, whereas they were 30.6 degrees BL and 18.2 degrees MD for MS. GP had TOC of 35.5 degrees BL and 24 degrees MD. GP had significantly higher TOC values than the other groups (0.001

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Section: Discussioncontrasting

confidence: 81%

Convergence Angles of Clinical Tooth Preparations for Metal Ceramic Restorations Among Dental Students and General Practitioners

Hinnara¹,

Barngkgei

Nassar³

2017

Avicenna J Dent Res

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“…There is an inherent lack of standardised methodology regarding the capturing of this information. In literature the TOC is commonly shown to be measured by projecting silhouettes of prepared dies (Ohm and Silness, 1978;Nordlander et al, 1988;Ayad et al, 2005), photocopies (Noonan and Goldfogel, 1991), photographs (Leempoel et al, 1987), or creating a digital cross sectioned image (Annerstedt et al, 1996;Oilo et al, 2003;Güth et al, 2013). Time consuming methods of measuring TOC can deter clinicians from accurately recording the TOC.…”

Section: Discussionmentioning

confidence: 99%

“…Ohm and Silness (1978) tested dentistry students in their final year and found the TOC angles for vital teeth ranged from 19°C to 27°C. Other studies testing students and practitioners (Leempoel et al, 1987;Nordlander et al, 1988;Noonan and Goldfogel, 1991;Annerstedt et al, 1996;Ayad et al, 2005) all reported higher convergence angles showing discrepancies between recommended and actual values carried out in practice.…”

Section: Introductionmentioning

confidence: 88%

Total Occlusal Convergence and Margin Design in Relation to Survival of Glass-Ceramic Crowns: A Review

Tiu¹,

Waddell²,

Al-Amleh³

et al. 2014

Current Research in Dentistry

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This review aims to report on preparation geometry parameters and their relation to crown failures in complete glass-ceramic clinical studies. A review of the literature was conducted in MEDLINE/PubMed with an additional manual search. The articles were screened through an inclusion and exclusion criteria and information regarding the Total Occlusal Convergence (TOC) angle and margin design was extracted along with its survivability. Nineteen articles were found, three were retrospective studies and 16 were prospective. Three articles specified TOC and 16 articles specified their margin design. Eighty failures were reported but lack of information between core and margin design and failures meant the relationship was inconclusive. There were a limited number of long-term clinical studies assessing glass-ceramic complete crowns. These studies provided insufficient information regarding the TOC angles of the prepared crowns and its potential effect on the survivability of glass-ceramic crowns. Further studies need to be conducted to determine how the TOC and margin design can affect the survival rates of glass-ceramic complete crowns.

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“…Estudios muestran una disparidad considerable de los registros de AC de las preparaciones y los recomendados por la literatura dental (Smith et al, 1999;Weed, 1980;Norlander et al, 1988;Ayad et al, 2005), considerando una ventaja alcanzar un adecuado ángulo de convergencia de la preparación con un mínimo de remoción dentaria (Ayad et al).…”

Section: Introductionunclassified

“…Hay diferentes métodos indirectos que han sido usados para medir el AC de los dientes preparados y que incluyen herramientas de marcación con microscopio, microscopio goniométrico y retroproyectores (Smith et al;Ayad et al;Ohm & Silness;Annerstedt et al, 1996). También, el AC puede ser medido usando una serie de imágenes fotocopiadas del mismo troquel con el cual se puede magnificar, para permitir una medición precisa (Noonan & Goldfogel, 1991).…”

Section: Introductionunclassified

Algoritmo Matemático para Cuantificar Directamente el Ángulo de Convergencia en Preparaciones de Dientes Artificiales

Flores¹,

Lebrecht²,

Figueroa³

2011

Int. J. Morphol.

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RESUMEN: El objetivo de este trabajo fue determinar un algoritmo matemático para cuantificar directamente el ángulo de convergencia (AC) en troqueles de preparaciones dentarias. El modelo experimental consistió en preparaciones coronarias simuladas sobre troqueles de yeso, en el cual el AC fue calculado por tres formulas trigonométricas. Las formulas fueron obtenidas de un modelo matemático en el cual la preparación coronaria representa una forma de pirámide truncada, la cual permite una proyección triangular en un plano. Fueron realizadas 60 mediciones in situ sobre las paredes de 15 troqueles. Se obtuvo una imagen de cada troquel usando una cámara digital (Schick® CDR). El AC fue medido usando la herramientas del software (Control). Los datos fueron analizados estadísticamente y se aplicaron test de propagación de errores. Los ángulos calculados con las tres fórmulas matemáticas ([F1], [F2] y [F3]) mostraron un alto nivel de correlación con el grupo control excepto para dos muestras. Dentro de las limitaciones de este estudio podemos concluir que a través de este algoritmo matemático, es posible cuantificar directamente el AC de las preparaciones coronarias en troqueles. Actualmente la evaluación de los AC tanto en preparaciones realizadas por alumnos de pregrado de odontología como por dentistas, se hacen de manera subjetiva. Las tres fórmulas presentadas en el algoritmo tiene una correlación alta para cuantificar el AC en troqueles. La [F3], es la que mas correlación logra en todas las muestras (0,89).

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Assessment of convergence angles of tooth preparations for complete crowns among dental students

Cited by 56 publications

References 20 publications

Convergence Angles of Clinical Tooth Preparations for Metal Ceramic Restorations Among Dental Students and General Practitioners

Convergence Angles of Clinical Tooth Preparations for Metal Ceramic Restorations Among Dental Students and General Practitioners

Total Occlusal Convergence and Margin Design in Relation to Survival of Glass-Ceramic Crowns: A Review

Algoritmo Matemático para Cuantificar Directamente el Ángulo de Convergencia en Preparaciones de Dientes Artificiales

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