A technique to guide implant placement with the long axis parallel to the path of insertion of removable partial dentures.

This article describes a novel technique that allows the planning and placing of dental implants with their long axis parallel to a path of insertion chosen for a prospective removable partial denture. The technique is straightforward, uses digital technologies efficiently, and enables prosthetically driven implant placement. It also optimizes the outcome when dental implants are used in association with removable partial dentures.

Accuracy of 3D printed scan bodies for dental implants using two additive manufacturing systems: An in vitro study.

This study compared the accuracy of implant scan bodies printed using stereolithography (SLA) and digital light processing (DLP) technologies to the control (manufacturer's scan body) Scan bodies were printed using SLA (n = 10) and DLP (n = 10) methods. Ten manufacturer's scan bodies were used as control. The scan body was placed onto a simulated 3D printed cast with a single implant placed. An implant fixture mount was used as standard. The implant positions were scanned using a laboratory scanner with the fixture mounts, manufacturer's scan bodies, and the printed scan bodies. The scans of each scan body was then superimposed onto the referenced fixture mount. The 3D angulation and linear deviations were measured. The angulation and linear deviations were 1.24±0.22° and 0.20±0.05 mm; 2.63±0.82° and 0.34±0.11 mm; 1.79±0.19° and 0.32±0.03 mm; for the control, SLA, and DLP, respectively. There were statistical differences (ANOVA) among the three groups in the angular (p<0.01) or linear deviations (p<0.01). Box plotting, 95% confidence interval and F-test suggested the higher variations of precision in the SLA group compared to DLP and control groups. Scan bodies printed in-office have lower accuracy compared to the manufacturer's scan bodies. The current technology for 3D printing of implant scan bodies needs trueness and precision improvements.

Effects of remeshing algorithms on trueness of fit when used to compress .stl files for dental models: A narrative review.

OBJECTIVES: In recent years, there has been a transition toward using and storing digitized dental models instead of physical casts. The size of .stl files is directly correlated with a need for higher computer processing power, longer operation time and a need for more storage space. Several studies explored the impact of decreasing the mesh resolution to decrease file size while maintaining trueness of fit between the original and modified files. Multiple authors suggested to compress .stl files by removing a fixed percentage of triangular faces. However, certain variables which are not yet fully investigated may impact the outcome of remeshing and compressing .stl files. METHODS: This narrative review explores concepts that may have a significant impact on the outcome of remeshing and compressing .stl file. RESULTS: When restructuring digital meshes to compress .stl files, variables such as initial mesh density, adaptive resolution, scanning technology, rendition and remeshing algorithms, as well as the clinical situation, can affect the outcome. CONCLUSION: Prior to applying subjective compression to .stl files by a static percentage, multiple variables must be considered to ensure trueness of fit is preserved. The results obtained for specific situations may not extrapolate to others. CLINICAL SIGNIFICANCE: Remeshing algorithms used to reduce .stl file size, or to optimize the files prior to manufacturing, may cause the loss of important data. Further research is needed to guide clinicians safely altering digital meshes.

Accuracy of Implant Placement Position Using Nondental Open-Source Software: An In Vitro Study.

PURPOSE: To evaluate the accuracy of implant placement position using two different dental implant planning software. MATERIALS AND METHODS: A set of Digital Imaging and Communications in Medicine (DICOM) files from a cone beam computed tomography of a patient missing maxillary right first premolar was used. Implant planning was done using two open-source programs: A nondental 3D Slicer/Blender (3DSB) software and a commercial dental implant treatment planning program: Blue Sky Plan 4 (BSP4). An intraoral scan of the same patient was used to create a standard tessellation language (STL) file of the maxillary arch and later printed into 20 identical casts. Ten surgical guides were printed for each group as well. A dental implant (3.8 mm × 12 mm, Biohorizons) was placed into each cast using fully guided surgical protocol. The horizontal displacements at the implant cervical platform and at the implant apex as well as the angulation displacements were measured using digital scanning of the implant scan bodies and were analyzed using a 3D compare software. Statistical analyses were conducted (⍺ = 0.05) using t-test and F-test to examine differences in trueness and precision, respectively. RESULTS: The average horizontal deviations for the platform and the apex, respectively, were 0.33 ± 0.12 mm and 0.76 ± 0.30 mm for 3DSB and 0.44 ± 0.21 mm and 0.98 ± 0.48 mm for BSP4. The average angulation deviations for 3DSB and BSB4 were 2.34 ± 0.93° and 3.07 ± 1.57°, respectively. There were no statistical differences in the means (t-test) of the platform, apex, and angulation deviations (p = 0.16, p = 0.19, and p = 0.18, respectively). There were statistical differences in the variances (F test) of the platform (p = 0.043) and angulation (p = 0.049) deviations but not the apex (p = 0.059) deviations. CONCLUSIONS: The combination of nondental open-source software, 3D Slicer/Blender can be used to plan implant guided surgery with an accuracy similar to commercial dental software with slightly higher precision. Open-source nondental software can be considered as an alternative in dental implant treatment planning and guided surgery.

Finite element analysis of a one-piece zirconia implant in anterior single tooth implant applications.

This study evaluated the von Mises stress (MPa) and equivalent strain occurring around monolithic yttria-zirconia (Zir) implant using three clinically simulated finite element analysis (FEA) models for a missing maxillary central incisor. Two unidentified patients' cone-beam computed tomography (CBCT) datasets with and without right maxillary central incisor were used to create the FEA models. Three different FEA models were made with bone structures that represent a healed socket (HS), reduced bone width edentulous site (RB), and immediate extraction socket with graft (EG). A one-piece abutment-implant fixture mimicking Straumann Standard Plus tissue level RN 4.1 X 11.8mm, for titanium alloy (Ti) and Zir were modeled. 178 N oblique load and 200 N vertical load were used to simulate occlusal loading. Von Mises stress and equivalent strain values for around each implant model were measured. Within the HS and RB models the labial-cervical region in the cortical bone exhibited highest stress, with Zir having statistically significant lower stress-strain means than Ti in both labial and palatal aspects. For the EG model the labial-cervical area had no statistically significant difference between Ti and Zir; however, Zir performed better than Ti against the graft. FEA models suggest that Ti, a more elastic material than Zir, contributes to the transduction of more overall forces to the socket compared to Zir. Thus, compared to Ti implants, Zir implants may be less prone to peri-implant bone overloading and subsequent bone loss in high stress areas especially in the labial-cervical region of the cortical bone. Zir implants respond to occlusal loading differently than Ti implants. Zir implants may be more favorable in non-grafted edentulous or immediate extraction with grafting.