Sometimes patients ask why they should save a tooth with a root canal and crown when they can just place an implant. A recent survey by Azarpazhooh et. al
. demonstrated a declining pattern of preference for root canal therapy (RCT) in favor of implant supported crowns (ISC) among general dentists, periodontists, prosthodontists and oral surgeons as opposed to endodontists. This declining pattern showed a significantly higher preference for ISC over RCT retreatment.
While dental implants are an important treatment option for our edentulous patients, implants, cannot replace the periodontium (tooth, ligament, gingival fibers, alveolar bone) that belong to the tooth. Extraction of a tooth removes the genotype which produces the phenotype that gives the tooth its characteristics. Most, if not all, of the long term challenges with implants such as crestal bone loss, loss of gingival architecture, occlusal trauma and perioimplantitis are due to the lack of periodontium.
|Gastrulation of the Diploblast: The germ layers form as the|
ectoderm (orange) move inward forming the
endoderm (red). Source
Can you remember that dental embryology class? Remember the endoderm, ectoderm and mesoderm? While you may not have thought about these tissues for many years, understanding the difference between teeth and implants goes back to that first semester of dental school.
All human tissues form from one of these three embryonic tissue layers (endoderm, mesoderm, ectoderm).
The tooth is formed from ectodermal tissue and it's close developmental association with the mesenchymal (mesodermal) tissue.
The tooth bud is an invagination of the ectodermal tissue into the mesodermal tissue. Neural crest cells (ectodermal cells) that blend with the mesodermal cells are called ectomesenchymal cells. The interaction of the ectoderm and ectomesenchymal cells form the enamel organ which forms the tooth.
So as the tooth develops through the bud, cap, bell stages, the enamel organ will form the enamel, the dental papilla will form the dentin and pulp tissue and the dental sac will form all the supporting structures. These supporting structures (periodontium) include cementum, periodontal ligament and alveolar bone. The alveolar bone, including the lamina dura are derived from osteoblasts formed from ectomesenchymal cells.
|The tooth develops as an invagination of the ectoderm|
into the mesodermal tissue. This makes the periodontium
(tooth and its surrounding supportive structures -
gingiva, ligament, alveolar bone) of ectodermal origin.
Once the tooth is lost, these tissues are irreplaceable.
So the tooth, and its supporting structures are derived from ectodermal tissue and ectomesenchymal tissue. In other words, the periodontium BELONGS to the tooth.
So why does this matter? It matters because when a tooth is extracted, the periodontium is lost. The periodontium is what makes a tooth look, function and feel like a tooth.
The maxillary or mandibular bone is derived from mesodermal tissue. When the dental implant is placed into the jaw bone, it is placed into bone derived from the mesodermal tissue. That bone has different quality and function from the bone associated with the periodontium.
That is why the dental implant does not feel, look or function "just like a tooth". They are not the same. This important point should not be forgotten.
Come and learn more about teeth and implants at our upcoming Inner Space Seminar - This Friday, April 11th, 2014
- featuring Dr. Hessam Nowzari.