Finding Calcified Canals Using A Microscope

Teeth & Dental Implants: Not the Same

At the recent AAE Convention, Dr. Hessam Nowzari presented a lecture on implant outcomes.  Dr. Nowzari is a diplomate of the American Board of Periodontology and the former director of advanced periodontics at USC from 1995 to 2012.

Dr. Nowzari discussed the difference between the tooth and an implant from a unique perspective. Often left out of the discussion regarding implants is the importance of the periodontium and how loss of the the periodontium (tooth, periodontal ligament, dental papilla, supracrestal fibers, lamina dura) affects the remaining gingival esthetics, including the esthetics around the dental implant.

It is well known that anterior gingival esthetics around an implant are one of the most challenging parts of implant dentistry.  The reason this is so challenging, is that the natural periodontal tissues (see image) that give the gingiva it's phenotype (appearance) are gone.  An implant's best chance at "natural-looking" gingiva/papilla is a natural tooth next door!  Dental papilla belong to teeth. 

While implants have an important part in dentistry, an implant can never effectively reform the periodontium.  The bundle bone and the family of fibers (dentogingival, dentoperiosteal, alveologingival, periosteogingival, interpapillary, intergingival, circular, semicircular, transgingival, intercircular, transeptal fibers) that create the architecture of the dental papilla all belong to the tooth.

This debate between implants and endodontics should not exist.  Implants and root canals are not alternative treatments.  If a tooth and its surrounding periodontium is in tact, we should make every effort to preserve them, because an implant cannot restore these periodontal tissues and loss of these tissues leads to a host of other challenges.

 Dr. Nowzari hosts a periodontal & implant symposium that may be one of the few (if only) implant CE events that is not sponsored or underwritten with any commercial interest (also available for download).  It may also be the only of its type where endodontists and implant surgeons are participate together.  We would highly recommend you check it out.

Why Is It Better to Save a Natural Tooth?

A patient recently asked...

 I'm a healthy 47 year old male. My upper central incisor (#9) was struck (trauma). It cracked vertically to the gum line, and then cracked horizontally to the lateral edge (resulting in an inverted "L" shaped fracture).

My general dentist first tried applying a layer of bonding, which appeared to be acceptable both aestetically and structurally.

6 weeks later, severe pain started to develop. I went back to my dentists and he said that there is no sign of infection, but that the pain is likely from the nerve dying. We agreed that we should go with either a root canal + crown, or implant + crown.

As a mechanical engineer, I'm leaning towards the implant, because it seems more "fool proof", especially considering that the existing tooth has been structurally compromised down to the gumline.

But the one thing that still has me second-guessing the implant option is that endodontists and periodontists both seem to universally agree that "It's better to save the tooth whenever possible."

So I have to ask: WHY???

Why is it "better to save the natural tooth" if it is subject to future decay (in particular at the base of the crown) and is also subject to brittleness following the root canal?

As a mechanical engineer, I like the prospect of an inert metal or zirconium implant that is not subject to these potential future modes of failure.

Please share your insights in the context specific to my situation described above. Much appreciated. Thank you. 

While it may seem a simple solution to replace a tooth with an implant and then avoid future issues like decay or root fracture, there are some important reasons why the specialists are recommending preserving the natural tooth if possible.

Periodontal Ligament attaches the root to the bone

Teeth and implants are not the same. The main difference between a tooth and an implant is that a tooth has a periodontal ligament. This ligament attaches the root to the bone and acts as a shock absorber for the tooth.  Without a periodontal ligament, when you touch, tap or chew on the tooth, you cannot feel the tooth or how hard you are biting.

The sensory function of the periodontal ligament helps you know when something is wrong with your tooth. If the tooth is hitting too hard, the ligament senses it. If there is infection around the tooth, the ligament senses it. The sensory function of the periodontal ligament is very important to dental health.

The periodontal ligament also supports the surrounding bone. When the ligament (tooth) is removed, bone loss naturally follows. The periodontal ligament also is a home to multiple cell lines which support the bone such as: osteoclasts, osteoblasts, fibroblasts, cementoblasts, cementoclasts, and stem cells. The periodontal ligament allows the tooth to be moved through the bone (orthodontics).

The periodontal ligament has an important role with esthetics.  When the ligament is removed, and bone loss naturally occurs, gingival recession follows. This can change the esthetics of the tooth, especially in the anterior esthetic area.

The periodontal ligament also has an immunological purpose. The ligament and the gingival connective tissue fibers form a barrier to protect the bone from bacterial invasion.

There are times when the natural tooth cannot be saved.  If the root is fractured, then the tooth is not savable.  The endodontist is the most qualified specialist to determine if a root is fractured.  At Superstition Spring Endodontics, we use microscopes and focused field, high resolution CT scans to aid in the diagnosis of root fracture.

The periodontal ligament is the difference!

In these particular cases, a dental implant may be the ideal way to replace a missing tooth.  Marketing of dental implants by manufacturers has made this treatment options well known to the public, however, dental implants are not free of complications or need for revision (additional) treatment over time. By understanding the complications that can occur with implants, it will help to understand why specialists recommend, "saving the tooth if possible".

The ligament is a shock absorber

Many of the complications with dental implants can be associated with the lack of a periodontal ligament. Here are a few of the ways the lack of periodontal ligament can cause complications with dental implants.

The periodontal ligament is the shock absorber for your tooth.  Can you imagine driving a car without shocks? An implant, without a ligament, has no proprioception (sense of feeling). This means it is difficult for you to "feel" how hard the teeth are hitting together. Porcelain chipping, cracking and loosening of implant screws are all common complications with implants, mostly due to the lack of a periodontal ligament and the proprioception it provides.



Fortunately, with implants adjacent to natural teeth, you maintain proprioception from the adjacent natural teeth so your chewing can still feel the same. However, it is difficult to feel if the implant crown is hitting too hard, like you would with a natural tooth. Your dentist must be careful to get the implant crown adjusted just right, and will often times flatten the crown to prevent excessive force on the implant or make the biting contact light.

Bone loss over time is expected

The periodontal ligament transfers the force from the tooth to the bone. That constant transfer of force to the bone, keeps the bone functioning around the root.  When the periodontal ligament is gone, bone loss naturally follows. Some studies say that up to 0.2mm/yr of bone loss can be expected. There are theories as to why this occurs. Some think its simply the mechanical forces on the implant transferred to the bone that causes the recession.

Bone loss in anterior can cause esthetic defects

Loss of bone around an implant can cause unsightly changes in the anterior esthetic zone. While the implant may be functioning, esthetic failure is a well known complication with anterior implants.

Peri-implantitis is the growth of bacterial biofilms on the implant surface, causing chronic inflammation leading to bone loss.  Many people are not aware that an implant can get peri-implantitis, just like a tooth can get periodontitis, both of which can eventually lead to the loss of the implant/tooth.   The periodontal ligament plays an important role in the preservation of the bone around a tooth.

Historically, implants have been classified as "surviving" or "failed" based upon mobility of the implant. New implant studies have suggested that implant intervention may need to be done at earlier stages before too much bone loss has occurred.  It was proposed that surgical intervention may need to be done when an implant is considered "ailing" or "failing" rather than waiting until enough bone loss has occurred to consider it "failed".

In a recent study published in the Journal of Oral and Maxillofacial Implants, a comparative study between the success rates of implants and root canals revealed no significant difference in the two options and emphasized that treatment decisions should be made on factors other than outcomes.  In other words, neither of these treatment options can claim to be more successful than the other.  These treatments are different, and each has its own pro's and con's.

Implants have an important role in dentistry.  I routinely recommend implant placement for missing teeth or teeth that are too damaged to save. However, implants are not teeth and we should try to preserve our natural teeth if possible.

For more information on the longevity of implants vs. natural teeth, click here or here.

Root Canal or Implant?

The latest version of Inside Dentistry (July/August 2008, volume 4, number 7) has a very interesting cover story by Allison M. DiMatteo BA, MPS. As an endodontist, I have been watching this debate develop for quite some time. I think it is important to determine what is behind this effort to pit one dental specialty against another.

This particular article seeks the opinion of endodontists and periodontists alike. All sides agree that implants are a great way to replace missing teeth. There is consensus that there is value to retaining natural teeth. The disagreement seems to come from the debate about when to remove a tooth in order to place an implant.

There are some who argue that implants are more successful than endodontically treated teeth. This is despite the evidence that shows that implants and endodontically treated teeth have similar, almost identical success rates.

Richard Mounce DDS, an endodontist, points out that the only controversy between endodontics and implants is "primarily economic and more artificially manufactured than exists in reality...There are clear indications for endodontic therapy and clear indications for implant therapy. Rarely are these treatment options so evenly weighted that when considered side by side (as to their advantages and disadvantages) that there should be a 'competition' or 'controversy', most especially when the patient's interest is put first".

According to Gregori M. Kurtzman DDS, "as a general rule, it is better to save a tooth...if you can". Restorability is the key factor in determining when a tooth needs to be removed. Ability to get a good margin, not violate biological width, cracks, strength of furcation, crown:root ratio etc. are all important factors in determining the restorability of the tooth. An endodontically treated tooth with a poor restoration, will generally not have long term success.

However in the same article, Dr. Kurtzman goes on to questions the success rates of endodontic surgery, and even the value of endodontic retreatment. Dr. Kurtzman points out that the financial investment into retreatment, like all treatment options which does not have 100% success rate, may be better made in a more predictable treatment of an implant.
That argument shows lack of understanding and appreciation for modern microscopic endodontic therapy.

I routinely recommend implant therapy for patients. What concerns me as a specialist is to see the marketing techniques and lack of proper endodontic evaluation during the treatment planning of implant cases. All of our mailboxes are full of marketing journals filled with clinical cases of implant placement.

Here is an example of two cases in the same issue of Inside Dentistry p.104-108.

This case is described as a "peri-apically involved maxillary incisor resulting from a failed root canal." Treatment options were reviewed and informed consent was obtained. Based on the patient's desire to reduce trauma and treatment time, it was decided to perform immediate implant placement. First of all, failed root canal is not an accurate diagnosis. The radiograph does not show the peri-apex. As best as we can tell the periodontal ligament looks fairly normal at the periapex. Was retreatment an option discussed? If it was, would it not be considered "less truamatic" than extraction and immediate implant placement? Not to mention the ability of a natural tooth to retain the crestal bone levels. Unless this tooth has a vertical fracture, of which there is no evidence, endodontic retreatment is a better option.

Another case from the same article shows a 27 year old female with a "symptomatic maxillary left lateral incisor with a history of endotherapy with a core build-up and crown". Active infection was noted with perilous fistula and exudate at the gingival margin. The prognosis of this tooth was deemed "hopeless".

Again, the endodontic evaluation of this tooth is incomplete. The anterior "bite-wing" type film certainly shows a normal crestal bone level, however, it is impossible to evaluate the endodontic therapy and is not a sufficient pretreatment radiograph. The conclusion that this tooth has a "hopeless" is premature.

Inadequate endodontic evaluation seems to be commonplace in many of the published clinical cases and those marketing dental implants. As mentioned above, there should be little controversy regarding endodontics and implants. Our specialties should not be pitted against one another, but should work together to meet the needs of our patients.

Sources:

DiMatteo, A. "Making the Right Move: Planning Your Clinical Strategy", Inside Dentistry, July/August 2008. p122-133.

Malek, M. "Done in a Day: Immediate Tooth Replacement with Definitive Prosthesis", Inside Dentistry, July/August 2008. p104-108.