Crowns And Extra Coronal Restorations - Endodontic Considerations - The Pulp, The Root Treated Tooth, And The Crown

J. M. Whitworth,¹ A. W. G. Walls² and R. W. Wassell<sup>3

1</sup>Senior Lecturer, Department of Restorative Dentistry, The Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW; ²Professor, Department of Restorative Dentistry, The Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW; ³Senior Lecturer in Restorative Dentistry, Department of Restorative Dentistry, The Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW



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Endodontic considerations is the fourth in the series on crowns and other extra-coronal restorations. This article focuses strongly on contemporary biological principles, and is not intended to provide a comprehensive review of commercially available materials and techniques. Principles are illustrated in a variety of clinical case scenarios.

IN BRIEF A consideration of the impact of crowning on the dental pulp, and the special issues involved in crowning root-treated teeth. The damaging effects of crown preparation. Assessment and preparation of root-treated and non root-treated teeth to minimize endodontic complications. Special considerations in the temporisation and restoration of root-treated teeth.

 

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CROWNS AND EXTRA-CORONAL RESTORATIONS: 1. Changing patterns and the need for quality 2. Materials considerations 3. Pre-operative assessment 4. Endodontic considerations 5. Jaw registration and articulator selection 6. Aesthetic control 7. Cores for teeth with vital pulps 8. Preparations for full veneer crowns 9. Provisional restorations 10. Impression materials and technique 11. Try-in and cementation of crowns 12. Porcelain veneers 13. Resin bonded metal restorations

Crowns should not be made without consideration of the teeth which lay the foundations for them. In this article, important principles are outlined for the assessment of root-treated and non root-treated teeth before crowning, avoiding endodontic complications during crown fabrication, and special considerations in the temporisation and restoration of root-treated teeth.

Pulp morbidity in crowned teeth
Dental pulp is the highly vascular, richly innervated soft tissue structure whose principal role is tooth formation. But even after teeth are erupted into the mouth and fully formed, the dental pulp is not a redundant organ. Pulp tissue retains the important function of supporting its secretory odontoblasts which lay down reparative dentine in defensive response to dental injuries throughout life. There is also some evidence that the pulp may be involved in a pressure-receptive function, limiting the possibility of damaging functional overload on teeth.¹

If this were not sufficient justification to preserve healthy pulps, then the desire to do patients no harm and to avoid the pain, swelling and suffering which often accompanies the injury and demise of a pulp surely must be.

An insulating coverage of dentine and an impervious layer of enamel protect the pulps of healthy, intact teeth from injury. Crown preparation places the pulp at risk in a number of ways. High speed stripping of hard tissue poses the threat of pulpal overheating, with disturbance of microcirculation, vascular stasis, thrombosis, reduced blood flow and internal bleeding.² It also opens a multitude of dentinal tubules that communicate directly with the pulp. The deeper the dentine is cut, the more permeable it is,³ and the more vulnerable the pulp becomes to chemical, physical and microbial irritants. The microbial threat presented by the oral flora is by far the most serious, and is capable of heralding intense inflammatory changes, with micro-abscess formation and progressive pulpal necrosis.^{4, 5}

References:

1. Randlow K, Glanz P O. On cantilever loading of vital and non vital teeth: an experimental clinical study. Acta Odontol Scand 1986; 44: 271-277.

2. Zach L. Pulp lability and repair: effect of restorative procedures. Oral Surg 1972; 33: 111-121.

3. Pashley D H. Clinical considerations of microleakage. J Endod 1990; 16: 70-77.

4. Cox C F, Subay R K, Suzuki S, Suzuki S H, Ostro E. Biocompatibility of various dental materials: pulp healing with a surface seal. Int J Periodont Rest Dent 1996; 16: 241-251.

5. Bergenholtz G. Iatrogenic injury to the pulp in dental procedures: aspects of pathogenesis, management and preventive measures. Int Dent J 1991; 41: 99-110.