A Comparison of Convergence Angles of Crown preparations in an undergraduate programme at a Tertiary Institution
DOI:
https://doi.org/10.17159/2519-0105/2021/v76no10a3Keywords:
Convergence angles, full coverage crown preparation; dental students, preclinical prosthodonticsAbstract
The retention of indirect dental restorations is of concern for clinicians as it influences the success of clinical outcomes. Retention and resistance are dependent on many factors including the convergence angles of the opposing axial wall tapers. Adequate axial wall taper is important in crown preparation to improve physical retention and increase resistance of the restoration. Aims and objectives To determine and compare the convergence angles (CA) of KaVo® teeth prepared for full coverage crown restorations by fourth year dental students in a preclinical fixed prosthodontics module in a five year dentistry training programme. Methodology Crown preparations produced by fourth year dental students at Sefako Makgatho Health Sciences University (SMU), South Africa, over a period of 3 years were included in this study. These preparations were digitally captured using CAD-CAM imaging technology. The images were analysed in ImageJ® software to determine the mesio-distal convergence angles. Statistical analysis was undertaken
using SPSS ver. 27 for Windows. Results The overall mean convergence angle of 15.38° ± 6.68° was computed for n=75 crown preparations. ANOVA revealed a significant difference (p<0.05) in the CA among the three cohorts (2017: 16.87° ± 6.94°; 2018: 17.23° ± 6.13°; 2019: 12.02° ± 5.86°). A reasonable proportion of dental students n=25 (33%) achieved the recommended CA of 6° to 12°.
Conclusion
This study indicates that with objective evaluation tools, it is possible to improve on the intended guidelines for crown preparations during undergraduate teaching and training in pre-clinical Fixed Prosthodontics.
Downloads
References
Smith CT, Gary JJ, Conkin JE, Franks HL. Effective taper criterion for the full veneer crown preparation in preclinical prosthodontics. Journal of Prosthodontics. 1999;8(3):196- 200.
Dodge W, Weed R, Baez R, Buchanan R. The effect of convergence angle on retention and resistance form. Quintessence international. 1985;16(3):191-4.
Ferro K, Morgano S. The Glossary of Prosthodontic Terms; Edition Nine. J prosthet dent. 2017;117(5S):16-92.
Shillingburg H, Sather D, Wilson Jr E, Cain J, Mitchel D, Blanco L. Fundamentals of fixed prosthodontics 4th Ed. Chicago. Quintessence. 2012;119(130):299-345.
Rosensteil S, Land M, Fujimoto J. Contemporary Fixed Prosthodontics 4th ed St louis. Mosby; 2006.
Wilson Jr AH, Chan DC. The relationship between preparation convergence and retention of extracoronal retainers. Journal of Prosthodontics. 1994;3(2):74-8.
El-Ebrashi MK, Craig RG, Peyton FA. Experimental stress analysis of dental restorations. Part III. The concept of the geometry of proximal margins. The Journal of prosthetic dentistry. 1969;22(3):333-45.
Saunders W, Saunders E. Prevalence of periradicular periodontitis associated with crowned teeth in an adult Scottish subpopulation. British dental journal. 1998;185(3):137-40.
Blair F, Wassell R, Steele J. Crowns and other extracoronal restorations: Preparations for full veneer crowns. British dental journal. 2002;192(10):561-71.
Malone WF, Tylman SD, Koth DL. Tylman's theory and practice of fixed prosthodontics: Ishiyaku EuroAmerica, Incorporated; 1989.
Jørgensen K. The relation between retention and angle of convergence in cemented veneer crowns. Tandlaegebladet. 1955;59(2):94-8.
Kaufman EG, Coelho DH, Colin L. Factors influencing the retention of cemented gold castings. The Journal of Prosthetic Dentistry. 1961;11(3):487-502.
Marghalani TY. Convergence angles of metal ceramic crowns prepared by dental students. The Journal of prosthetic dentistry. 2014;112(5):1250-6.
Mack PJ. A theoretical and clinical investigation into the taper achieved on crown and inlay preparations.
Journal of Oral Rehabilitation. 1980;7(3):255-65.
Aleisa K, Al‐Dwairi ZN, Alwazzan K, Al-Moither M, Al-Shammari M, Lynch E. Convergence angles of clinical tooth preparations achieved by dental students at King Saud University, Saudi Arabia. Journal of dental education. 2013;77(9):1154-8.
Abdulla F, Khamis H, Milosevic A, Abuzayda M. Convergence angles of all-ceramic full crown preparations performed in Dubai private practice. Journal of clinical and experimental dentistry. 2018;10(12):e1192.
Bobak CA, Barr PJ, O’Malley AJ. Estimation of an interrater intra-class correlation coefficient that overcomes common assumption violations in the assessment of health measurement scales. BMC medical research methodology. 2018;18(1):1-11.
Ayad MF, Maghrabi AA, Rosenstiel SF. Assessment of convergence angles of tooth preparations for complete crowns among dental students. Journal of Dentistry. 2005;33(8):633-8.
Wiskott HA, Nicholls JI, Belser UC. The relationship between abutment taper and resistance of cemented crowns to dynamic loading. International journal of Prosthodontics. 1996;9(2).
Annerstedt AL, Engström U, Hansson A, Jansson T, Karlsson S, Liljhagen H, et al. Axial wall convergence of full veneer crown preparations Documented for dental students and general practitioners. Acta Odontologica Scandinavica. 1996;54(2):109-12.
Patel PB, Wildgoose DG, Winstanley RB. Comparison of convergence angles achieved in posterior teeth prepared for full veneer crowns. European Journal of Prosthodontics and Restorative Dentistry. 2005;13(3):100.
Leempoel P, Lemmens PL, Snoek P, Van't Hof M. The convergence angle of tooth preparations for complete crowns. The Journal of prosthetic dentistry. 1987;58(4):414-6.
Nordlander J, Weir D, Stoffer W, Ochi S. The taper of clinical preparations for fixed prosthodontics. The Journal of prosthetic dentistry. 1988;60(2):148-51.
Goodacre CJ, Campagni WV, Aquilino SA. Tooth preparations for complete crowns: an art form based on scientific principles. The Journal of prosthetic dentistry. 2001;85(4):363-76.
Virdee S, Addy L, Milward P, Lynch C. Convergence angles for full veneer crown preparation completed by undergraduate students in a dental teaching hospital. British dental journal. 2018;224(8):641-5.
Noonan Jr JE, Goldfogel MH. Convergence of the axial walls of full veneer crown preparations in a dental school environment. The Journal of prosthetic dentistry. 1991;66(5):706-8.
Sato T, Mutawa NA, Okada D, Hasegawa S. A clinical study on abutment taper and height of full cast crown preparations. Journal of medical and dental sciences. 1998;45(3):205-10.
Ghafoor R, Rahman M, Siddiqui AA. Comparison of convergence angle of prepared teeth for full veneer metal ceramic crowns. J Coll Physicians Surg Pak. 2011;21(1):15-8.
Emir F, Ayyıldız S. Evaluation of the trueness and precision of eight extraoral laboratory scanners with a complete-arch model: a three-dimensional analysis. journal of prosthodontic research. 2019;63(4):434-9.
Robinson P, Lee J. The use of real time video magnification for the pre-clinical teaching of crown preparations. British Dental Journal. 2001;190(9):506-10.
Downloads
Published
Issue
Section
License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
.png){kind=spacer}