Ask Dr. Christensen

In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers. If you would like to submit a question to Dr. Christensen, please send an email to info@pccdental.com.

by Gordon J. Christensen, DDS, MSD, PhD

Question ...

I have placed many crowns on lower anterior teeth, but some of them require endodontic therapy soon afterwards. A few of the crowns have broken the tooth preparations off from the root during service. What type of crown is the least traumatic for lower anterior teeth, and would veneers be less of a problem for these small teeth?

Answer from Dr. Christensen ...

Any aggressive restoration on lower anterior teeth is difficult and potentially dangerous to the teeth. In my opinion, major restorations on lower anterior teeth are among the most difficult procedures in the profession because of the small size of the teeth and the relatively large size of the dental pulps. When possible, ceramic veneers can be far better restorations for lower anterior teeth than crowns. When veneers are placed, the lingual surfaces of the teeth are not prepared, and normal oral hygiene procedures can be accomplished on the lingual surfaces. Additionally, veneers do not require aggressive cutting of the proximal, facial, or incisal portions of the teeth. Thus, veneers do not traumatize properly prepared lower anterior teeth to the same extent as crown preparations. The aesthetic result obtainable with lower anterior veneers is excellent, and it usually exceeds the aesthetic result of porcelain-fused-to-metal crowns. However, placement of ceramic veneers on lower anterior teeth requires meticulous care and attention to detail. Binocular loupe magnification is suggested. I prefer 4X loupes when finalizing these preparations and for finishing the restorations, although I usually wear 2.5X loupes for most other types of oral treatment. If crowns are required because of gross tooth destruction, I suggest as minimal tooth preparations as possible for crowns — a conservative, porcelain-fused-to-metal preparation usually works best. Placement of all-ceramic crowns on these small teeth is asking for pulpal damage and endodontic treatment. All-ceramic crowns require significantly deeper cutting than porcelain-fused-to-metal crowns.

Some continuing-education groups are emphasizing deep preparations for veneers. These deeper tooth preparations make laboratory construction of the veneers easier. However, potential pulpal damage caused by the deeper preparations is greater, and bond-to-tooth structure is less because the preparations are almost all in dentin. Veneer retention is lower than when preparations are kept primarily on enamel. Conservative veneer tooth preparations are my strong choice for minimally invasive lower anterior restorations.

One of our recent videos, C902B "Veneers for Lower Anterior Teeth," shows the conservative anterior veneer technique in detail. For more information, contact Practical Clinical Courses at (800) 223-6569, fax (801) 226-8637, or visit our Web site at www.pccdental.com.

Question ...

When a patient breaks a significant piece from an anterior tooth, and the pulp is not exposed, but pink-colored dentin is clearly visible over the near exposure, what is the most appropriate treatment before placing the resin-based composite restoration?

Answer from Dr. Christensen ...

It is difficult to determine if pulpal damage has occurred when a tooth is fractured. However, the laws of physics would have us believe that if the blow to the tooth caused a fracture, the force was dissipated as the tooth broke and therefore did not intrude upon root into the bone or traumatize the small nerves emerging from the root. I am always in favor of trying to restore the tooth without endodontic therapy. The tooth should be allowed to heal for a few weeks after the restoration is placed. If it remains symptomatic, endodontic therapy can be accomplished later.

In the past, calcium hydroxide was placed on near-pulp exposures. Calcium hydroxide therapy has become controversial, since some clinicians have suggested placement of resin-based bonding agents or resin-reinforced-glass-ionomer liners on the dentin of the near pulp exposure. However, it is interesting to observe that recently published research on pulp capping still shows calcium hydroxide to be as effective as or better than bonding agents. A treatment that is currently popular and one with which I have had predictable success is placement of resin-reinforced-glass-ionomer on the near-pulp exposure. Products such as Vitrebond (3M ESPE) or Fuji Lining Cement (GC) placed on the dentin of the near-pulp exposure acts similar to a self-etching primer, and they have a significant film thickness to ensure adequate coverage of the deeply exposed dentin.

Our video C598C "Effective Pulp Capping" shows this concept well. For more information, contact Practical Clinical Courses at (800) 223-6569, fax (801) 226-8637, or visit our Web site at www.pccdental.com.


Dr. Christensen is a practicing prosthodontist in Provo, Utah. He is the founder and director of Practical Clinical Courses, an international continuing-education organization for dental professionals initiated in 1981. Dr. Christensen is a co-founder (with his wife, Rella) and senior consultant of Clinical Research Associates, which, since 1976, has conducted research in all areas of dentistry and publishes its findings to the dental profession in the well-known CRA Newsletter. He is an adjunct professor at Brigham Young University and the University of Utah. Dr. Christensen has educational videos and hands-on courses on the above topics available through Practical Clinical Courses. Call (800) 223-6569 or (801) 226-6569.

Dr. Christensen's views do not necessarily reflect the opinions of the editorial staff at Dental Economics.

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