Research and Education| Volume 114, ISSUE 1, P67-74, July 2015

Download started.


Reporting numeric values of complete crowns. Part 1: Clinical preparation parameters


      Statement of problem

      An implemented objective measuring system for measuring clinical tooth preparations does not exist.


      The purpose of this study was to compare clinically achieved tooth preparations for ceramic crowns by general dentists with the recommended values in the literature with an objective measuring method.

      Material and methods

      Two hundred thirty-six stone dies prepared for anterior and posterior complete ceramic crown restorations (IPS e.max Press; Ivoclar Vivadent) were collected from dental laboratories. The dies were scanned and analyzed using the coordinate geometry method. Cross-sectioned images were captured, and the average total occlusal convergence angle, margin width, and abutment height for each preparation was measured and presented with associated 95% confidence intervals.


      The average total occlusal convergence angles for each tooth type was above the recommended values reported in the literature. The average margin widths (0.40 to 0.83 mm) were below the minimum recommended values (1 to 1.5 mm). The tallest preparations were maxillary canines (5.25 mm), while the shortest preparations were mandibular molars (1.87 mm).


      Complete crown preparations produced in general practice do not achieve the recommended values found in the literature. However, these recommended values are not based on clinical trials, and the effects of observed shortfalls on the clinical longevity of these restorations are not predictable.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Prosthetic Dentistry
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Prothero J.H.
        Prosthetic dentistry.
        Medico-Dental Publishing Co, Chicago1923: 742
        • Jorgensen K.D.
        The relationship between retention and convergence angle in cemented veneer crowns.
        Acta Odontol Scand. 1955; 13: 35-40
      1. The glossary of prosthodontic terms.
        J Prosthet Dent. 2005; 94: 27
        • El-Ebrashi M.K.
        • Craig R.G.
        • Peyton F.A.
        Experimental stress analysis of dental restorations. IV. The concept of parallelism of axial walls.
        J Prosthet Dent. 1969; 22: 346-353
        • Gilboe D.B.
        • Teteruck W.R.
        Fundamentals of extracoronal tooth preparation. Part I. Retention and resistance form.
        J Prosthet Dent. 1974; 32: 651-656
        • Kaufman E.G.
        • Coelho D.H.
        • Colin L.
        Factors influencing the retention of cemented gold castings.
        J Prosthet Dent. 1961; 11: 487-502
        • Wilson Jr., A.H.
        • Chan D.C.
        The relationship between preparation convergence and retention of extracoronal retainers.
        J Prosthodont. 1994; 3: 74-78
        • Ohm E.
        • Silness J.
        The convergence angle in teeth prepared for artificial crowns.
        J Oral Rehabil. 1978; 5: 371-375
        • Aleisa K.
        • Al-Dwairi Z.N.
        • 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.
        J Dent Educ. 2013; 77: 1154-1158
        • Alhazmi M.
        • El-Mowafy O.
        • Zahran M.H.
        • Uctasli S.
        • Alkumru H.
        • Nada K.
        Angle of convergence of posterior crown preparations made by predoctoral dental students.
        J Dent Educ. 2013; 77: 1118-1121
        • Al-Omari W.M.
        • Al-Wahadni A.M.
        Convergence angle, occlusal reduction, and finish line depth of full-crown preparations made by dental students.
        Quintessence Int. 2004; 35: 287-293
        • Annerstedt A.
        • Engstrom 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 Odontol Scand. 1996; 54: 109-112
        • Ayad M.F.
        • Maghrabi A.A.
        • Rosenstiel S.F.
        Assessment of convergence angles of tooth preparations for complete crowns among dental students.
        J Dent. 2005; 33: 633-638
        • Begazo C.C.
        • van der Zel J.M.
        • van Waas M.A.
        • Feilzer A.J.
        Effectiveness of preparation guidelines for an all-ceramic restorative system.
        Am J Dent. 2004; 17: 437-442
        • Dalvit D.L.
        • Parker M.H.
        • Cameron S.M.
        • Hawkins M.C.
        • Agar J.R.
        • Brousseau J.S.
        Evaluation of margin angles of collarless metal ceramic restorations.
        Gen Dent. 2004; 52: 148-150
        • Etemadi S.
        • Smales R.J.
        • Drummond P.W.
        • Goodhart J.R.
        Assessment of tooth preparation designs for posterior resin-bonded porcelain restorations.
        J Oral Rehabil. 1999; 26: 691-697
        • Ghafoor R.
        • Rahman M.
        • Siddiqui A.A.
        Comparison of convergence angle of prepared teeth for full veneer metal ceramic crowns.
        J Coll Physicians Surg Pak. 2011; 21: 15-18
        • Ghafoor R.
        • Siddiqui A.A.
        • Rahman M.
        Assessment of convergence angle of full-coverage porcelain fused to metal crowns in clinical practice.
        Indian J Dent Res. 2012; 23: 241-246
        • Guth J.F.
        • Wallbach J.
        • Stimmelmayr M.
        • Gernet W.
        • Beuer F.
        • Edelhoff D.
        Computer-aided evaluation of preparations for CAD/CAM-fabricated all-ceramic crowns.
        Clin Oral Investig. 2013; 17: 1389-1395
        • Kent W.A.
        • Shillingburg Jr., H.T.
        • Duncanson Jr., M.G.
        Taper of clinical preparations for cast restorations.
        Quintessence Int. 1988; 19: 339-345
        • Leempoel P.J.
        • Lemmens P.L.
        • Snoek P.A.
        • van ’t Hof M.A.
        The convergence angle of tooth preparations for complete crowns.
        J Prosthet Dent. 1987; 58: 414-416
        • Noonan Jr., J.E.
        • Goldfogel M.H.
        Convergence of the axial walls of full veneer crown preparations in a dental school environment.
        J Prosthet Dent. 1991; 66: 706-708
        • Nordlander J.
        • Weir D.
        • Stoffer W.
        • Ochi S.
        The taper of clinical preparations for fixed prosthodontics.
        J Prosthet Dent. 1988; 60: 148-151
        • Okuyama Y.
        • Kasahara S.
        • Kimura K.
        Quantitative evaluation of axial wall taper in prepared artificial teeth.
        J Oral Sci. 2005; 47: 129-133
        • Patel P.B.
        • Wildgoose D.G.
        • Winstanley R.B.
        Comparison of convergence angles achieved in posterior teeth prepared for full veneer crowns.
        Eur J Prosthodont Restor Dent. 2005; 13: 100-104
        • Poon B.K.
        • Smales R.J.
        Assessment of clinical preparations for single gold and ceramometal crowns.
        Quintessence Int. 2001; 32: 603-610
        • Rafeek R.N.
        • Marchan S.M.
        • Seymour K.G.
        • Zou L.F.
        • Samarawickrama D.Y.
        Abutment taper of full cast crown preparations by dental students in the UWI School of Dentistry.
        Eur J Prosthodont Restor Dent. 2006; 14: 63-66
        • Sato T.
        • Al Mutawa N.
        • Okada D.
        • Hasegawa S.
        A clinical study on abutment taper and height of full cast crown preparations.
        J Med Dent Sci. 1998; 45: 205-210
        • Smith C.T.
        • Gary J.J.
        • Conkin J.E.
        • Franks H.L.
        Effective taper criterion for the full veneer crown preparation in preclinical prosthodontics.
        J Prosthodont. 1999; 8: 196-200
        • Marghalani T.Y.
        Convergence angles of metal ceramic crowns prepared by dental students.
        J Prosthet Dent. 2014; 112: 1250-1256
        • Yoon S.S.
        • Cheong C.
        • Preisser Jr., J.
        • Jun S.
        • Chang B.M.
        • Wright R.F.
        Measurement of total occlusal convergence of 3 different tooth preparations in 4 different planes by dental students.
        J Prosthet Dent. 2014; 112: 285-292
        • Tiu J.
        • Al-Amleh B.
        • Waddell J.N.
        • Duncan W.J.
        Clinical tooth preparations and associated measuring methods: a systematic review.
        J Prosthet Dent. 2015; 113: 175-184
        • Rekow E.D.
        • Harsono M.
        • Janal M.
        • Thompson V.P.
        • Zhang G.
        Factorial analysis of variables influencing stress in all-ceramic crowns.
        Dent Mater. 2006; 22: 125-132
        • Tiu J.
        • Waddell J.N.
        • Al-Amleh B.
        • Jansen van Vuuren W.A.
        • Swain M.V.
        Coordinate geometry method for capturing and evaluating crown preparation geometry.
        J Prosthet Dent. 2014; 112: 481-487
      2. International Organization for Standardization. Dentistry-designation system for teeth and areas of the oral cavity. ISO 3950. 2009. Avaiable at: Last accessed June 15, 2015.

        • Shillingburg H.T.
        • Sather D.A.
        • Stone S.E.
        Fundamentals of fixed prosthodontics.
        4th ed. Quintessence Publishing Co Inc, Chicago2012: 131-148
        • Ayad M.F.
        • Rosenstiel S.F.
        • Salama M.
        Influence of tooth surface roughness and type of cement on retention of complete cast crowns.
        J Prosthet Dent. 1997; 77: 116-121
        • Cameron S.M.
        • Morris W.J.
        • Keesee S.M.
        • Barsky T.B.
        • Parker M.H.
        The effect of preparation taper on the retention of cemented cast crowns under lateral fatigue loading.
        J Prosthet Dent. 2006; 95: 456-461
        • Zidan O.
        • Ferguson G.C.
        The retention of complete crowns prepared with three different tapers and luted with four different cements.
        J Prosthet Dent. 2003; 89: 565-571

      Linked Article