It is hard to argue today with the observation that there is an overwhelming global tendency in both the medical and dental world to overtreat patients who present with conditions that could often be managed with much less invasive protocols. One example is the decision to edentulate patients when performing a full arch reconstruction. As I will demonstrate in this article, there is another, less invasive, alternative: evaluating “arch distribution” with an eye to maintaining strategic teeth.

The term “terminal dentition” is a dentist-made term which, while it seems easy to comprehend (a patient who is indisputably losing their teeth), is often used loosely (no pun intended). The decision to edentulate patients needs to be carefully analyzed, as its nature is inherently multifactorial. Therefore the clinical team and the patient need to engage in a communication process aimed at clarifying the possible implications (precautions, limitations, etc.) of the treatment plan that has been chosen.

In a previous article, we described an algorithm that allows the treating team and the patient to objectively decide whether to extract the remaining teeth or to keep them. The algorithm looks at the correlation between the number of remaining teeth, and their distribution in the arch, as they relate to lip mobility/esthetic challenge.

Examples of different remaining teeth distribution in the maxillary arch.
Figure 1: Examples of different remaining teeth distribution in the maxillary arch.

There are many scenarios (Fig. 1) when it comes to remaining teeth in patients that are partially edentulous. On a fundamental level, when it comes to distribution, a bilateral and symmetric spread is conceivably favorable, relative to potential functional and esthetic outcomes—as opposed to a unilateral distribution, which tends to be more challenging to manage prosthetically from both functional and esthetic standpoints.

Unilateral vs bilateral distribution.
Figure 2: Unilateral vs bilateral distribution.

As can be appreciated in Figure 2, assuming there are only 4 teeth remaining in the maxillary arch, Patient B presents a more favorable distribution when compared to Patient A.

 

A “Visual Essay” Case Study

The following visual essay shows how the algorithm clearly provides the treating team with a compelling case to keep either keep or remove the remaining teeth, particularly as it relates to the distribution when there are only a few of them.

Patient's initial presentation with multiple missing posterior and anterior teeth.
Figure 3: Patient's initial presentation with multiple missing posterior and anterior teeth.

This patient (Fig. 3) was diagnosed elsewhere with so-called “terminal dentition” and was treatment planned for extractions, bone reduction, implant placement, and the fabrication of a fixed hybrid implant-supported solution.

Occlusal and frontal view of the clinical condition.
Figure 4: Occlusal and frontal view of the clinical condition.
Radiographic evaluation of the remaining teeth.
Figure 5: Radiographic evaluation of the remaining teeth.

Upon clinical and radiographic examination (Fig. 4-5), the patient presented with only four remaining teeth in the maxillary arch. A qualitative assessment of such remaining teeth was performed, and as can be easily evidenced in the figures, both lateral incisors and canines were not only structurally intact but also periodontally sound with a pretty homogenous gingival outline across the six anterior teeth.

Remaining teeth algorithm to either remove or maintain.
Figure 6: Remaining teeth algorithm to either remove or maintain.
Patient's condition: 4 remaining teeth, with bilateral/symmetric distribution and a relatively low esthetic risk based on preoperatory gingival harmony.
Figure 7: Patient's condition: 4 remaining teeth, with bilateral/symmetric distribution and a relatively low esthetic risk based on preoperatory gingival harmony.
Algorithm resulting in maintaining the teeth.
Figure 8: Algorithm resulting in maintaining the teeth.

Therefore, as seen in Figures 6-8, using the algorithm, these clinical findings unequivocally pointed our team towards recommending a prosthetic solution that considers not only keeping those remaining teeth, but keeping them unrestored.

At this point, the easiest way to convey our treatment solution to the patient is by means of a mockup, which can be attained either analogically or digitally.

Analog wax-up of the missing teeth in a cast.
Figure 9: Analog wax-up of the missing teeth in a cast.

A wax-up (Fig 9) is made to reproduce the contours of the missing teeth, from which a flipper type of provisional restoration is fabricated using PMMA resin (Fig. 10).

Fabrication of a flipper mockup for preliminary assessment.
Figure 10: Fabrication of a flipper mockup for preliminary assessment..

It is then tried-in intraorally so that the esthetic and functional outcome can be evaluated prior to embarking on active therapy.

Evaluation of the mockup.
Figure 11: Evaluation of the mockup.
Surgical planning using CBCT and implant placement software.
Figure 12: Surgical planning using CBCT and implant placement software.

Once the tooth position and contours of the missing teeth (Fig. 11) are accepted by the patient and the treating team, CBCT imaging is produced and the implant surgery is planned (Fig. 12), leading to the fabrication of a precise surgical template that is also fabricated using 3D printing technology.

Guided surgical placement of the implants.
Figure 13: Guided surgical placement of the implants.

The surgical specialist can then place the implants (Fig. 13) in both anterior and posterior segments, using the remaining four teeth to snugly hold the surgical template in place, during the drilling and implant insertion sequence.

Fabrication and insertion of the provisional implant-supported restorations.
Figure 14: Fabrication and insertion of the provisional implant-supported restorations.

After allowing time for osseointegration, provisional restorations are fabricated (Fig. 14) and inserted in order to road test the functional aspect of the three implant-supported segments (two posterior and one anterior), as well as to groom the soft tissues.

Fabrication of the implant-supported screw-retained ceramic restorations.
Figure 15: Fabrication of the implant-supported screw-retained ceramic restorations.

Once they are both validated, impressions are made for the fabrication of the definitive prosthetic restoration (Fig. 15), which consists of two posterior 3-unit fixed implant-supported partial dentures and two single-tooth implants for the central incisors, inserted clinically (Fig 16-17).

Progression of treatment depicting the preoperative, soft tissue grooming and insertion of the prosthesis.
Figure 16: Progression of treatment depicting the preoperative, soft tissue grooming and insertion of the prosthesis.
Insertion of the ceramic restorations.
Figure 17: Insertion of the ceramic restorations.

Excessive and often unnecessary bone reduction (Fig 18) should be avoided whenever possible.

Amount of bone reduction that would have been performed in order to accommodate for a fixed hybrid. (Given space requirements for prosthetic design of between 16 and 18mm.)
Figure 18: Amount of bone reduction that would have been performed in order to accommodate for a fixed hybrid (around 16mm).

Advantages of This Approach in a Full Arch Reconstruction

This visual essay depicts how distribution of the remaining teeth plays a fundamental role in the decision-making process to either keep or remove the remaining teeth, particularly when there are only a few of them remaining in the arch.

As is demonstrated in the case presented, bilateral distribution and symmetry are both conducive to keeping those remaining teeth in a full arch reconstruction and therefore providing a prosthetic design where the implants are restored as independent segments, providing compelling advantages such as:

  • Maintaining proprioception of those anterior teeth.
  • Allowing for optimal contingencies that may arise in the future. (For instance, if there is any ceramic chipping, the need to repair would be limited to a small segment rather than a full arch.)

In a time where there is a pervasive tendency to extract teeth and replace them with full arch implant-supported solutions, patients and dentists alike need to be thoroughly informed about the importance of evaluating arch distribution, and questioning if, and when, even a few remaining teeth should be maintained. 

 

Ricardo Mitrani, D.D.S., M.S.D., is a Spear Resident Faculty member.


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