Cadaveric Identification through Macroscopic Analysis of Dental Implants Subjected to High Temperatures-An Experimental Model.

The aim of this study was to determine the possibility of identifying a dental implant through the measurement of the apical width and the interspiral distance in a periapical radiograph after being subjected to high temperatures for certain lengths of time. In total, 11 fresh human anatomical models were selected, in which 137 implants were placed. Previous periapical radiographs were performed using parallelizers in each implant. Subsequently, the anatomical models were introduced into a crematory oven at different temperatures and for various durations: 500 °C/15 min, 500 °C/30 min, 700 °C/15 min, 800 °C/15 min, 800 °C/45 min, 500 °C/15 min, 700 °C/15 min, and finally, 1000 °C/120 min. After this, X-rays were taken via a parallel technique, and the apical width and interspiral distance were measured. The implants were disinserted, and the coronal width was used to calculate magnification or possible distortion. All data were analyzed by the Mann-Whitney U test. There were no statistically significant differences for the apical width parameter, except when the temperature was raised to 700 °C/15 min and to 800 °C/45 min. For the interspiral distance parameter, there were no statistically significant differences, except when the implants were subjected to 800 °C/15 min and 1000 °C/120 min. It was determined that there were changes in some groups based on the increase in temperature and exposure time. Neither of the two parameters were completely useful for the identification because some of the groups studied in both variables presented differences, which makes them difficult to identify correctly.

Removal capability, implant-abutment connection damage and thermal effect using ultrasonic and drilling techniques for the extraction of fractured abutment screws: an in vitro study.

The aim of this work was to analyze and compare the removal capability, conical internal hex implant-abutment connection damage and thermal effect using ultrasonic and drilling techniques for the extraction of fractured abutment screws. Twenty abutment screws were randomly fractured into twenty dental implants and randomly extracted using the following removal techniques: Group A: drilling technique without irrigation (n = 10) (DT) and Group B: ultrasonic technique without irrigation (n = 10) (UT). The dental implants were submitted to a preoperative and postoperative micro-computed tomography (micro-CT) scan to obtain a Standard Tessellation Language (STL) digital file that determined the wear comparison by morphometry. Moreover, the thermographic effects generated by the DT and UT removal techniques were registered using a thermographic digital camera. Comparative analysis was performed by comparing the volumetric differences (mm3) between preoperative and postoperative micro-CT scans and thermographic results (°C) using the Student t test. The DT extracted 8/10 and the US 9/10 abutment screws. The pairwise comparison revealed statistically significant differences between the volumetric differences of postoperative and preoperative micro-CT scans of the DT (- 0.09 ± - 0.02mm3) and UT (- 0.93 ± - 0.32mm3) study groups (p = 0.0042); in addition, the pairwise comparison revealed statistically significant differences between the thermographic values of the DT (38.12 ± - 10.82 °C) and UT (78.52 ± 5.43 °C) study groups (p < 0.001). The drilling technique without irrigation provides a less removal capability, less conical internal hex implant-abutment connection damage and less thermal effect than ultrasonic technique for the extraction of fractured abutment screws; however, the ultrasonic technique resulted more effective for the extraction of fractured abutment screws.

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.

Influence of the Computer-Aided Static Navigation Technique and Mixed Reality Technology on the Accuracy of the Orthodontic Micro-Screws Placement. An In Vitro Study.

To analyze the effect of a computer-aided static navigation technique and mixed reality technology on the accuracy of orthodontic micro-screw placement. Material and methods: Two hundred and seven orthodontic micro-screws were placed using either a computer-aided static navigation technique (NAV), a mixed reality device (MR), or a conventional freehand technique (FHT). Accuracy across different dental sectors was also analyzed. CBCT and intraoral scans were taken both prior to and following orthodontic micro-screw placement. The deviation angle and horizontal deviation were then analyzed; these measurements were taken at the coronal entry point and apical endpoint between the planned and performed orthodontic micro-screws. In addition, any complications resulting from micro-screw 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). The NAV study group showed statistically significant differences from the FHT (p < 0.001) and MR study groups (p < 0.001) at the apical end-point (p < 0.001), and the FHT group found significant differences from the angular deviations of the NAV (p < 0.001) and MR study groups deviations (p = 0.0011). Different dental sectors also differed significantly. (p < 0.001) Additionally, twelve root perforations were observed in the FHT group, while there were no root perforations in the NAV group. Conclusions: Computer-aided static navigation technique enable more accurate orthodontic micro-screw placement and fewer intraoperative complications when compared with the mixed reality technology and conventional freehand techniques.

A Comparative Analysis of the Piezoelectric Ultrasonic Appliance and Trephine Bur for Apical Location: An In Vitro Study.

To compare and contrast the accuracy of piezoelectric ultrasonic insert (PUI) and trephine bur (TB) osteotomy site preparation techniques for apical location. (1) Material and methods: A total of 138 osteotomy site preparations were randomly distributed into one of two study groups. Group A: TB technique (n = 69) and B: PUI technique (n = 69). A preoperative cone-beam computed tomography scan and an intraoral scan were performed and uploaded to implant-planning software to plan the virtual osteotomy site preparations for apical location. Subsequently, the osteotomy site preparations were performed in the experimental models with both osteotomy site preparation techniques and a postoperative CBCT scan was performed and uploaded into the implant-planning software and matched with the virtually planned osteotomy site preparations to measure the deviation angle and horizontal deviation as captured at the coronal entry point and apical end-point between osteotomy site preparations using Student's t-test statistical analysis. (2) Results: The paired t-test found statistically significant differences at the coronal entry-point deviations (p = 0.0104) and apical end-point deviations (p = 0.0104) between the TB and PUI study groups; however, no statistically significant differences were found in the angular deviations (p = 0.309) between the trephine bur and piezoelectric ultrasonic insert study groups. (3) Conclusions: The results showed that the TB is more accurate than the PUI for apical location.