Dr. Oded Bahat of Beverly Hills, California, shares his insights about planning for dynamic physical change based upon the decades of patient follow-up of implant restorations that he has carried out. A well-known clinician, Dr. Oded Bahat maintains a private practice limited to periodontics in Beverly Hills, California, USA. Not only a clinician, but also a popular international lecturer and a prolific writer, he has published over 30 scientific articles.
Dr. Richard Sullivan: You have always emphasized the importance of extra-oral and facial parameters in your pre-operative data gathering and treatment. Now this has expanded to an emphasis on adult craniofacial changes. Would you explain this progression?
Dr. Oded Bahat: To support a treatment plan that includes extensive reconstruction, analyzing the entire face is essential in my opinion. I can then determine the possibilities for future esthetics.
Intraoral esthetics is a part of facial esthetics. What we observe in a face are convexities and reflected highlights. These contours allow us to determine shapes, space, distances. These parameters are different between a youthful and aged face. Contours of the lower third of the face are affected by the combination of both hard and soft tissue augmentation procedures as well as the dental reconstruction—the teeth themselves, the arch form, which affects lip support, and support of lower facial height structures.
This analysis has always been based on conditions as they present, which is a moment in time. When planning for implants to support a restoration, we have always proceeded with the assumption of a more or less static relationship of implants relative to teeth in both the same arch and the opposing arch. Now we are more aware that this is not true in some cases. Neither the jaws nor the face as a whole are static.
These figures are full head scans of two different men (taken for other medical indications) and used here to illustrate general craniofacial changes. Please note: There are variations gender-specific to women. The first three images show lateral and frontal skull views and formatting with facial features of a 36 year-old man. The last three images show corresponding views of an 89 year-old man.
Are these changes truly noticeable?
Bahat: For some individuals very noticeable, and in some situations, difficult to treat. The change can be subtle. For instance, dentists will sometimes have a patient mention that a space has opened between a tooth and an implant restoration. That is common. What brings it to their attention is food impaction that was not originally a problem.
Other people who have a maxillary implant restoration of single or multiple teeth may begin to notice that the implant restoration is becoming shorter relative to the incisal edges of the adjacent natural teeth, accompanied by asymmetry of the soft tissue.
What is actually occurring is that the teeth and soft tissue are moving down in a harmonious way, but the implant and its associated restoration are fixed in position. This results in thinning of the bone and soft tissue on the labial aspect of the implant.
What are some of the more severe cases you have seen?
Bahat: Severe vertical asymmetry is the most noticeable and difficult to treat. Replacing the crown for someone with a high smile line would result in a long tooth and obvious soft tissue asymmetry.
We have seen this in men and women still in their 30s, people who had congenitally missing lateral incisors replaced with an implant-supported crown in their early 20s.
We have also seen people with larger implant restorations in one quadrant that do not keep pace, you might say, with the changes occurring with the jaw structures and teeth in the other three quadrants.
This causes significant changes in occlusion, placing the natural teeth at risk when the implant restoration is no longer able to support the occlusion as designed. In essence, the rest of the bone and teeth have moved away from the stationary implant restoration.
We are facing the result of continuous, physiologically normal changes and a stationary element. This means that the focus cannot be only on the implant restoration, as the effect of craniofacial changes could be most pronounced on the remaining dentition, remote from the implant site.
You mention a woman in her 20s—of an age where we don’t ordinarily consider growth to be a risk factor. Is there an age at which we can expect this potential consequence to go away?
Bahat: What we have found is that the potential for craniofacial changes as described are lifelong. In women there is often an accelerated change, thus greater risk of disharmony occurring in the mid 40s and in men between 45 and 50. Both from our own observations and also as reported by Torsten Jemt, people treated in their 80s can still be affected by these changes in their 90s, so no age can be considered past the point of potential occurrence.
Knowing this information now, how has this affected your treatment planning and surgical approach?
Bahat: Reviewing forensic anthropology, facial plastic surgery and adult orthodontic studies, we know that when these changes occur, they are 3-dimensional, with multiple vectors. The magnitude and exact direction varies.
Facial morphology does yield some clues, which has affected my planning in several ways. One is that whenever possible the 3-dimensional positioning of the implant is placed as close as possible toward the likely direction of growth—and therefore away from potential future bone resorption—without compromising the final esthetic and restorative result. This reduces the short- and medium-term effect.
I also tend to choose the minimum diameter of implant suitable—from a biomechanical requirements point-of-view—for a specific site, and consider designs that are more easily retrievable should this become necessary in extreme cases.
Another factor I take into account is grafting, especially in the anterior esthetic areas. Now I am considering the incorporation of a non-resorbable layer of particulate graft on the facial aspect in addition to autogenous bone. Since the autogenous graft behaves as native bone, adding non-resorbable graft material will create scar-like tissue and will camouflage or hide the grayish appearance due to tissue thinning facial to the implant.
For prospective patients, they are informed about this possibility and considerations that will be taken on their behalf prior to treatment. This is not really a complication of the implant or the restoration. It is rather a normal physiologic phenomena of the aging face and skull.
What advice would you give our readers based on your findings?
Bahat: I can only speak for the partially edentulous jaws as well as asymmetrical implant placement.
For patients already treated, understand that we cannot see or measure the changes occurring, we can only see the effects. Most importantly, when implants and teeth are within the same arch, occlusion must be checked routinely for unequal or unfavorable changes that dictate some corrective action.
If changes do occur in contacts or tooth length that necessitate replacement of the restoration, advise the patient that this may still occur again—in essence their face is “still growing.” Using a screw-retained replacement whenever possible will facilitate future restorative treatment.
If you have a patient with high esthetic expectations and a high smile line, understand they are at higher risk because vertical discrepancy cannot be resolved by just replacing a crown.
For patients still to be treated, learn more about and anticipate the potential vectors of future changes and, without other compromises, incorporate this information into augmentation procedures, 3-dimensional implant positioning and restorative designs. Emphasize for every patient and co-treating dentist the necessity of routine occlusal assessment and arch integrity to protect the patient from changes before they become harmful.