Digital technique to analyze the wear of screw-retained implant supported metal-ceramic dental prostheses and natural tooth as antagonist: a pilot study.

The aim of this study was to describe a novel digital technique to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.Materials and methods Ten patients were consecutively included to rehabilitate partial edentulism by dental implants. Both the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were submitted to a digital impression through an intraoral scan to generate a Standard Tessellation Language digital file preoperatively (STL1), at 3 months (STL2), and 6 months (STL3) follow-up. Afterwards, an alignment procedure of the digital files (STL1-STL3) was performed on a reverse engineering morphometric software (3D Geomagic Capture Wrap) and volume changes at the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were analyzed using Student's t-test. Moreover, Gage R&R statistical analysis was conducted to analyze the repeatability and reproducibility of the digital technique.Results Gage R&R showed a variability attributable to the digital technique of 3.8% (among the measures of each operator) and 4.5% (among operators) of the total variability; resulting repeatable and reproducible, since the variabilities were under 10%. In addition, statistically significant differences were shown at the wear volume (µm3) of both the natural tooth as antagonist (p < 0.0001) and the screw-retained implant-supported metal-ceramic dental prostheses between 3- and 6-months follow-up (p = 0.0002).Conclusion The novel digital measurement technique results repeatable and reproducible to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.

Comparative analysis of two navigation techniques based on augmented reality technology for the orthodontic mini-implants placement.

To analyze and compare the accuracy and root contact prevalence, comparing a conventional freehand technique and two navigation techniques based on augmented reality technology for the orthodontic self-drilling mini-implants placement. Methods Two hundred and seven orthodontic self-drilling mini-implants were placed using either a conventional freehand technique (FHT) and two navigation techniques based on augmented reality technology (AR TOOTH and AR SCREWS). Accuracy across different dental sectors was also analyzed. CBCT and intraoral scans were taken both prior to and following orthodontic self-drilling mini-implants placement. The deviation angle and horizontal were then analyzed; these measurements were taken at the coronal entry point and apical endpoint between the planned and performed orthodontic self-drilling mini-implants. In addition, any complications resulting from mini-implant placement, such as spot perforations, were also analyzed across all dental sectors.Results The statistical analysis showed significant differences between study groups with regard to the coronal entry-point (p < 0.001), apical end-point(p < 0.001) and angular deviations (p < 0.001). Furthermore, statistically significant differences were shown between the orthodontic self-drilling mini-implants placement site at the coronal entry-point (p < 0.0001) and apical end-point (p < 0.001). Additionally, eight root perforations were observed in the FHT group, while there were no root perforations in the two navigation techniques based on augmented reality technology.Conclusions The navigation techniques based on augmented reality technology has an effect on the accuracy of orthodontic self-drilling mini-implants placement and results in fewer intraoperative complications, comparing to the conventional free-hand technique. The AR TOOTH augmented reality technique showed more accurate results between planned and placed orthodontic self-drilling mini-implants, comparing to the AR SCREWS and conventional free-hand techniques. The navigation techniques based on augmented reality technology showed fewer intraoperative complications, comparing to the conventional free-hand technique.

Accuracy of computer-aided static and dynamic navigation systems in the placement of zygomatic dental implants.

BACKGROUND: Zygomatic implants are widely used in the rehabilitation of severely atrophic maxillae, but implant placement is not without risks, and it can potentially cause damage to related anatomical structures. The aim of this study was to perform a comparative analysis of the accuracy of static navigation systems in placing zygomatic dental implants in comparison to dynamic navigation systems. METHODS: Sixty zygomatic dental implants were randomly allocated to one of three study groups, categorized by which implant placement strategy was used: A: computer-aided static navigation system (n = 20) (GI); B: computer-aided dynamic navigation system (n = 20) (NI); or C: free-hand technique (n = 20) (FHI). For the computer-aided study groups, a preoperative cone-beam computed tomography (CBCT) scan of the existing situation was performed in order to plan the approach to be used during surgery. Four zygomatic dental implants were inserted in each of fifteen polyurethane stereolithographic models (n = 15), with a postoperative CBCT scan taken after the intervention. The pre- and postoperative CBCT scans were then uploaded to a software program used in dental implantology to analyze the angular deviations, apical end point, and coronal entry point. Student's t-test was used to analyze the results. RESULTS: The results found statistically significant differences in apical end-point deviations between the FHI and NI (p = 0.0053) and FHI and GI (p = 0.0004) groups. There were also statistically significant differences between the angular deviations of the FHI and GI groups (p = 0.0043). CONCLUSIONS: The manual free-hand technique may enable more accurate placement of zygomatic dental implants than computer-assisted surgical techniques due to the different learning curves required for each zygomatic dental implant placement techniques.

Accuracy of zygomatic dental implant placement using computer-aided static and dynamic navigation systems compared with a mixed reality appliance. An in vitro study.

Background: Analyze and compare the accuracy of zygomatic dental implant placement carried out using a static navigation surgery, a dynamic navigation surgery and an augmented reality appliance. Material and Methods: Eighty (80) zygomatic dental implants were randomly assigned to one of four study groups: A: static navigation implant surgery (n = 20) (GI); B: dynamic navigation implant surgery (n = 20) (NI); C: augmented reality appliance implant placement (n = 20) (ARI) and D: free hand technique (n = 20) (FHI). A preoperative cone-beam computed tomography (CBCT) scan of the existing situation was performed to plan the surgical approach for the computer assisted implant surgery study groups. Four zygomatic dental implants were placed in anatomical-based polyurethane models (n = 20) manufactured by stereolithography, and a postoperative CBCT scan was taken. Subsequently, the preoperative planning and postoperative CBCT scans were uploaded to dental implant software to analyze the coronal global, apical global, and angular deviations. Results were analyzed using linear regression models with repeated measures to assess the differences according to the group, according to the position, and the interaction between both variables. If statistically significant differences were detected, 2-to-2 comparisons were made between the groups/positions. Results: The results did not show statistically significant differences between the coronal global deviations of GI (5.54 ± 1.72 mm), NI (5.43 ± 2.13 mm), ARI (5.64 ± 1.11 mm) and FHI (4.75 ± 1.58 mm). However, showed statistically significant differences between the apical global deviations of FHI (3.20 ± 1.45 mm) and NI (4.92 ± 1.89 mm) (p = 0.0078), FHI and GI (5.33 ± 2.14 mm) (p = 0.0005) and FHI and ARI (4.88 ± 1.54 mm) (p = 0.0132). In addition, the results showed also statistically significant differences between the angular deviations of FHI (8.47º ± 4.40º) and NI (7.36º ± 4.12º) (p = 0.0086) and between GI (5.30º ± 2.80º) and ARI (9.60º ± 4.25º) (p = 0.0005). Conclusions: Free-hand technique provides greater accuracy of zygomatic dental implant placement than computer-assisted implant surgical techniques, and zygomatic dental implants placed in the anterior region are more accurate than in the posterior region. However, it is an in vitro study and further clinical studies must be conducted to extrapolate the results to the clinical setting. Key words:Implantology, computer assisted implant surgery, image-guided surgery, augmented reality, navigation surgery, zygomatic implants.

Influence of Static Navigation Technique on the Accuracy of Autotransplanted Teeth in Surgically Created Sockets.

The aim of this study was to analyse and compare the position of single-rooted autotransplanted teeth using computer-aided SNT drilling and conventional freehand (FT) drilling, by comparing the planned and performed position at the coronal, apical and angular level. MATERIALS AND METHODS: Forty single-root upper teeth were selected and distributed into the following study groups: A. Autotransplanted tooth using the computer-aided static navigation technique (SNT) (n = 20) and B. Autotransplanted tooth using the conventional free-hand technique (FT) (n = 20). Afterwards, the teeth were embedded into two experimental models and 10 single-root upper teeth were randomly autotransplanted in each experimental model. The experimental models were submitted to a preoperative cone-beam computed tomography (CBCT) scan and a digital impression by a 3D intraoral scan, in addition to a postoperative CBCT scan, after the autotransplantation. Datasets from postoperative CBCT scans of the two study groups were uploaded to the 3D implant planning software, aligned with the autotransplantation planning, and the coronal, apical and angular deviations were measured. The results were analysed using Student's t-test and Mann-Whitney non-parametric statistical analysis. RESULTS: Coronal (p = 0.079) and angular (p = 0.208) statistical comparisons did not present statistically significant differences; however, statistically significant differences between the apical deviation of the SNT and FT study groups (p = 0.038) were also observed. CONCLUSIONS: The computer-aided static navigation technique does not provide higher accuracy in the positioning of single-root autotransplanted teeth compared to the conventional free-hand technique.

A Replicable and Reproducible Digital Method for Quantifying Maxillary Sinus Airway Changes after Sinus Lifts Using the Lateral Window Approach Technique-A Retrospective Study.

In the present retrospective study, we aimed to assess the replicability and reproducibility of a novel digital measurement technique for analyzing the volumes of the left and right maxillary sinuses and the nasal and maxillary sinus airway complex after a sinus lift procedure using the lateral window approach, to provide an accurate measurement technique for easily applying in clinical practice and to allow pre-operative assessment of maxillary sinus lift surgery, avoiding complications and making surgery more predictable. MATERIAL AND METHODS: Thirty patients with partially edentulous posterior maxilla were selected and submitted to bilateral sinus lift using the lateral window approach technique, with grafting materials selected and submitted to cone beam computed tomography (CBCT) scans, both pre- and postoperatively. Then, datasets were uploaded to therapeutic digital planning software to measure the volume of the right and left maxillary sinuses and the nasal and maxillary sinus airway complex. Gage R&R statistical analysis was performed to assess the replicability and reproducibility of the digital measurement technique. RESULTS: The variability attributable to the novel digital measurement technique was 3.4% for replicability and 3.4% for reproducibility of the total variability of the samples. CONCLUSION: The novel digital method proposed is a replicable and reproducible technique for analyzing the volume of the right and left maxillary sinuses and the nasal and maxillary sinus airway complex after a sinus lift using the lateral window approach technique, allowing an accurate pre-operative assessment of maxillary sinus lift surgery, avoiding complications and making surgery more predictable.