Abstract
ObjectivesThe aim of this study was to evaluate the accuracy of fully guided orthodontic mini-implant (OMI) placements supported by tooth- (TBGs) or gingiva-borne silicone guides (GBGs) based on virtually superimposed lateral cephalograms on virtual plaster models.Materials and methodsLateral cephalograms and corresponding plaster models were virtually superimposed for the planning of OMI positions; fully guided TBGs and GBGs were fabricated (each, n = 10). A total of 40 OMIs were inserted in a paramedian position into the palate of 20 human cadavers. Postoperative cone-beam computer tomographies (CBCTs) were carried out, and an accuracy evaluation was performed by comparing preoperative planning models and postoperative CBCTs. Deviations of the axis, tip, centre of the shoulder and vertical position of each of the implants were evaluated. Furthermore, the transfer accuracy measured by postoperative CBCT scans were compared with the accuracy determined using an intraoral scanner.ResultsA significant deviation between TBGs (2.81° SD 2.69) and GBGs (6.22° SD 4.26) regarding implant angulation was evaluated (p = 0.005). Implant tip and implant shoulder deviations revealed no statistical differences between the guides. Accuracy values of oral scans regarding vertical deviations were significantly more inaccurate when compared with CBCTs (p < 0.001).ConclusionsThe accuracy of an OMI position can be significantly increased by using a guide extension over the teeth. Vertical implant positions presented the lowest deviations. Postoperative oral scans and CBCTs represent diverging accuracy measurements when compared with virtual planning.Clinical relevanceUsers must keep in mind that despite virtual planning deviations, inaccuracies of a few millimetres may occur.
Highlights
A report on mini-implants for orthodontic anchoring was first published by Gainsforth and Higley in 1945 [1]
The accuracy measured at the implant tip was slightly superior in TBG; Fig. 4 Deviation of angulation between virtual and real orthodontic miniimplant position (TBG = tooth-borne guide, gingiva-borne silicone guides (GBGs) = gingiva-borne guide)
Within the limits of this assessment, the vertical implant position was promising in the TBG and GBG groups
Summary
A report on mini-implants for orthodontic anchoring was first published by Gainsforth and Higley in 1945 [1]. Skeletal anchoring with OMIs has been successful due to its advantages with low patient compliance [2,3,4,5]. Mini-implants can be placed in the alveolar process between the roots, in the retromolar region or in the anterior palate [6]. Care must be taken at all times to be sure that no surrounding anatomical structures get damaged [7]. Interradicular insertion involves the risk of root damage [8]. Skeletal anchorages in the lower jaw, such as with screws used in
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