A new 3D-method to assess the inter implant dimensions in patients - A pilot study.

BACKGROUND

Complex implant treatments have steadily increased within implant prosthodontics. Based on the lower implant mobility, implant impressions need high accuracy in the model transfer to receive a high passive fit within the final prosthodontic restoration. To analyze the accurate 3-dimensional (3D) inter-implant-positions, a reference point is indispensable. However, there is no reference in the patients mouth, so the aim of the present study was to develop a new method based on a custom-made-measuring-aid (CMA) to assess the inter implant dimensions (InID) in patients.

MATERIAL AND METHODS

Initially an implant master model (IMM/patient equivalent) was digitized by computed tomography. A CMA was fixed on the impression posts and the inter implant dimensions (InID) were recorded with a coordinate measurement machine (CMM). For comparison to conventional and digital impression techniques, 10 impressions per technique were taken. InIDs for the IMM, the CMA and the two impression techniques were compared. To give a proof of principle, the new 3D-method was applied to three patients as pilot cases. Results for trueness and precision were analyzed by pairwise comparisons (< .05). All data were subjected to univariate ANOVA.

RESULTS

Mean deviation for InID ranged from 10.3±18μm(CMA) to 41.7±36μm(conventional). There were partially significant differences for InID between the CMA and the different impression techniques. There were no significant differences for InID within the CMA. The InID in the evaluation ranged from 42.3μm to 376.7μm(digital) and from 58.3μm to 274.0μm(conventional). There were partially significant differences between the techniques.

CONCLUSIONS

Within the limits of this study, with the developed method using a CMA it is possible to assess the true 3D-InID with a decisive higher accuracy than possible with a conventional or digital implant impression. Overall, the CMA in this study generated results that were deemed clinically useful for the investigated inter implant positions. Dental Implants, Dimensional Measurement Accuracy, Dental Impression Technique, Intraoral Scanner.