Abstract
Background:
Dental implants are an excellent option to replace single or multiple missing teeth with high success rates. Implants were originally placed “freehand” (FH) according to the available bone, but not necessarily in the best position for the final restoration, leading to both crown and implant failure.
Guided implant surgery, either fully guided (FG) or partially guided (PG), uses prosthodontically-driven digital planning for implant positioning. A surgical guide is then made and is used in surgery to guide implant placement. Studies have shown reasonable accuracy for guided surgery, but comparative studies are scarce against the FH placement. FH is still required in certain challenging situations, such as limited mouth opening or in the posterior part of the mouth when the guide is not feasible.
Aims:
This in-vitro study assessed the accuracy of FG implant surgery compared to PG and FH in two challenging clinical scenarios: 1) anterior vs posterior sites and 2) tooth-bounded vs tooth-mucosa (free-end) sites.
Methods:
The implant positions were digitally planned, and ten implants were placed in models according to the three treatment arms – FG, PG and FH. A healing abutment was scanned and imported into the planning software to compare the in vitro position with the virtually planned position.
Results:
For angulation, FG was more accurate in anterior sites compared to PG (2.1°) and FH (3.4°). FG was significantly more accurate than FH in both bounded and free-end sites, but there was no significant difference between FG and PG.
When assessing the vertical position, the mean difference in FG was nearly 2 mm for anterior sites and almost 1mm for posterior sites. Conversely, the horizontal differences in anterior and posterior sites were minimal, irrespective of the level of guidance or site.
The results for vertical and horizontal deviations were equivocal in both bounded and free-end sites, irrespective of guidance used, suggesting that an implant can be precisely positioned even without a guide in a free-end site.
Conclusion:
The results of the in-vitro study did not show that FG would be more accurate than PG and FH in either clinical scenarios.
A degree of guidance is beneficial for accurate angulation, especially for free-end sites where the absence of an adjacent tooth makes it difficult to have a reference point for correct angulation. Nevertheless, the depth control with FG surgery lacked accuracy with the implant platform ending above the crestal bone height.
Considering the differences seen in angulation, PG is an appropriate treatment modality for both bounded and free-end spaces in the posterior sites.
Overall, While FG shows better accuracy in some instances, PG and FH still remain suitable alternatives in certain challenging clinical scenarios.