Discussion : Three-dimensional computer-guided implant placement in oligodontia

This technical advanced article illustrated the benefit of a full three-dimensional virtual workflow to guide implant placement in oligodontia cases as well as that implants can be reliably placed at the planned positions with the technique proposed.

The described full three-dimensional virtual workflow has several advantages. First, the surgeon is pre-operatively better informed about the requirements for the prosthodontic treatment with regard to the implant position. Second, the patient is pre-operatively better informed about the surgical procedure as well as the prosthodontic end result. The current costs are a limitation of this technique as fully digital planning is more expensive in comparison to a conventional approach. The expectation is that these costs will decrease with the time as this technique will be used more often in the future and probably the costs of the dental technician can also be reduced. At the moment, the extra costs for a full digital planning are reimbursed by Dutch health insurance companies. However, to the best of our knowledge, this (extra) reimbursement is not common in many other countries.

The difference in position between the virtually planned and actually placed implants, according to our workflow, resembles the deviation in implant placement for virtually planned and placed implants in non-oligodontia patients [3,4,5,6]. Schneider et al. [4] report in their systematic review a mean deviation of 1.07 mm (95% CI 0.76–1.22 mm) at the shoulder and 1.63 mm (95% CI 1.26–2 mm) at the apex as well as a mean angular deviation of 5.26° (95% CI 3.94–6.58°). More recent studies report similar results [3, 6]. Thus, the accuracy of virtual implant planning in oligodontia patients is comparable to that reported in non-oligodontia cases.

A variety of factors (i.e. technical, product, mechanical, procedure and environmental factors) can affect the accuracy of implant placement [7]. Commonly, implant placement accuracy is higher by experienced surgeons [8], but patient-related factors are often less easy to control. Some progress has been made to control patient factors by using tooth-supported drilling templates, as demonstrated here; they enable a more precise transfer of the virtual implant planning to the surgical site than mucosa- or bone-supported templates [6, 9]. However, there is still a need to identify appropriate evaluation techniques and mechanisms capable of optimizing transfer precision and eliminating errors of three-dimensional planning and guiding systems for the partially dentate jaw [10]. Planning is complex, and high transfer precision is not always easy to accomplish, particularly in oligodontia cases with a large number of missing teeth. With the use of the described method, pre-operative implant planning is possible and placement is more predictable.