Effective taper criterion for the full veneer crown preparation in preclinical prosthodontics.

PURPOSE Effective taper criteria must define a realistic, measurable goal that the student can visualize and achieve. Six degrees is widely accepted as the taper criterion for the full veneer crown preparation. However, studies show the actual taper of most preparations to be greater than 12 degrees. The purpose of this study was to determine whether 12 degrees is an effective taper criterion for the full veneer crown preparation in preclinical prosthodontics instruction. MATERIALS AND METHODS A group of 191 full veneer crown preparations with 6 degrees as the taper criterion, and a group of 130 full veneer crown preparations with 12 degrees as the taper criterion were evaluated. All preparations were accomplished by preclinical dental students working on typodonts under examination conditions. RESULTS The overall mean taper for each group exceeded the targeted criterion. The overall mean taper for the 6 degrees group was 14,490. When 12 degrees was the criterion, the overall mean taper was 15,580. The t test results indicate significant differences (p < .0001) between the targeted criterion and the actual preparation mean taper in all samples except one: the faciolingual measurements in the 12 degrees group. The faciolingual measurement of 12,920 was not statistically significantly different (.0542) from the targeted criterion of 12 degrees. CONCLUSION The use of a 12 degrees taper criterion did not result in preclinical students achieving the goal of a 12 degrees taper. However, a 12 degrees criterion is more realistic than a 6 degrees criterion for full veneer crown preparations.

[1]  E Ohm,et al.  The convergence angle in teeth prepared for artificial crowns. , 1978, Journal of oral rehabilitation.

[2]  P H Feil,et al.  Designing preclinical instruction for psychomotor skills (II)--instructional engineering: task analysis. , 1994, Journal of dental education.

[3]  Stanley Daniel Tylman,et al.  Theory and practice of crown and bridge prosthesis , 1954 .

[4]  F. M. Gardner,et al.  Quantitative determination of taper adequate to provide resistance form: concept of limiting taper. , 1988, The Journal of prosthetic dentistry.

[5]  P H Feil,et al.  Designing preclinical instruction for psychomotor skills (III)--Instructional engineering: design phase. , 1995, Journal of dental education.

[6]  F. M. Gardner,et al.  New guidelines for preparation taper. , 1993, Journal of prosthodontics : official journal of the American College of Prosthodontists.

[7]  P J Mack,et al.  A theoretical and clinical investigation into the taper achieved on crown and inlay preparations. , 1980, Journal of oral rehabilitation.

[8]  K. Dreyer,et al.  The relationship between retention and convergence angle in cemented veneer crowns. , 1955 .

[9]  P A Snoek,et al.  The convergence angle of tooth preparations for complete crowns. , 1987, The Journal of prosthetic dentistry.

[10]  A. Wilson,et al.  The relationship between preparation convergence and retention of extracoronal retainers. , 1994, Journal of prosthodontics : official journal of the American College of Prosthodontists.

[11]  P H Feil,et al.  Designing preclinical instruction for psychomotor skills (I)--theoretical foundations of motor skill performance and their applications to dental education. , 1994, Journal of dental education.

[12]  Edward G. Kaufman,et al.  Factors influencing the retention of cemented gold castings , 1961 .

[13]  S. Karlsson,et al.  Axial wall convergence of full veneer crown preparations. Documented for dental students and general practitioners. , 1996, Acta odontologica Scandinavica.

[14]  W B Eames,et al.  Techniques to improve the seating of castings. , 1978, Quintessence of dental technology.

[15]  A Nimmo,et al.  Patient-centered competency-based education in fixed prosthodontics. , 1996, Journal of prosthodontics : official journal of the American College of Prosthodontists.

[16]  S. Ochi,et al.  The taper of clinical preparations for fixed prosthodontics. , 1988, The Journal of prosthetic dentistry.

[17]  M H Goldfogel,et al.  Convergence of the axial walls of full veneer crown preparations in a dental school environment. , 1991, The Journal of prosthetic dentistry.

[18]  Shillingburg Ht,et al.  Taper of clinical preparations for cast restorations. , 1988 .

[19]  R J Baez,et al.  The effect of convergence angle on retention and resistance form. , 1985, Quintessence international.

[20]  P Feil.  An assessment of the application of psychomotor learning theory constructs in preclinical laboratory instruction. , 1992, Journal of dental education.

[21]  C. Owen.  Retention and resistance in preparations for extracoronal restorations. Part II: Practical and clinical studies. , 1986, The Journal of prosthetic dentistry.