Thermal changes during implant site preparation with a digital surgical guide and slot design drill: an ex vivo study using a bovine rib model

Comparative Evaluation of Accuracy of Adjacent Parallel Implant Placements Between Dynamic Navigation and Static Guide: A Prospective Study

Aim The study aims to compare the accuracy of dynamic navigation (DN) and static guides (SGs) for simultaneous adjacent parallel placement of implants, the time taken for the surgery, and the ease of handling the instruments. Materials and methods This prospective trial was carried out at the Department of Implantology of Saveetha Dental College from October 2022 to February 2023. A total of 20 patients who needed simultaneous adjacent dental implants were allocated randomly into two groups: Group 1 SG surgery and Group 2 DN surgery. Forty implants were placed, 20 under DN and 20 under SG. Bucco-lingual displacement, apico-coronal displacement, mesiodistal displacement, and mesiodistal angulation were compared between the two groups. The patients' data in both groups were evaluated by operating surgeons along with the surgical time taken and the ease of handling of instruments. Results The 20 patients who underwent implant placement in the DN and SG groups all had adjacent missing teeth in posterior sites, including lower posteriors (70%) and upper posteriors (30%). There was improved precision in relation to the mesiodistal displacement and angulation of the anterior implant of the adjacent parallel implants. The mesiodistal displacement in Group 1 (SG) was 5.61 + 3.1 mm, which was higher than Group 2 (DN), which was 0.55 + 0.56 mm. The mesiodistal angulation was 3.1 + 2.9 degrees in Group 2 and 0.42 + 0.5 degrees in Group 1. The second implant had a significant difference (p < 0.005) in mesiodistal displacement, mesiodistal angulation, and bucco-lingual displacement. The difference between the intergroup surgical time (mean + SD) in Group 1 was 30 + 4.5 mins and in Group 2 was 60.7 + 10.1 mins, with p < 0.05 statistically significant. The comfort of the operator was better in the SG group. Conclusion Any digitally aided implant placement technique can improve placement accuracy but each has its downfalls. Achieving the highest levels of precision and long-lasting prosthetic results hinges on both the suitability of the chosen case and the expertise of the surgeon performing the implant placement.

On the thermal impact during drilling operations in guided dental surgery: An experimental and numerical investigation

In recent years, a major development in dental implantology has been the introduction of patient-specific 3D-printed surgical guides. The utilization of dental guides offers advantages such as enhanced accuracy in locating the implant sites, greater simplicity, and reliability in performing bone drilling operations. However, it is important to note that the presence of such guides may contribute to a rise in cutting temperature, hence increasing the potential hazards of thermal injury to the patient's bone. The aim of this study is to examine the drilling temperature evolution in two distinct methods for 3D-printed surgical dental guides, one utilizing an internal metal bushing system and the other using external metal reducers. Cutting tests are done on synthetic polyurethane bone jaw models using a lab-scale automated Computer Numeric Control (CNC) machine to find out the temperature reached by different drilling techniques and compare them to traditional free cutting configurations. Thermal imaging and thermocouples, as well as the development of numerical simulations using finite element modeling, are used for the aim. The temperature of the tools' shanks experienced an average rise of 2.4 °C and 4.8 °C, but the tooltips exhibited an average increase of around 17 °C and 24 °C during traditional and guided dental surgery, respectively. This finding provides confirmation that both guided technologies have the capability to maintain temperatures below the critical limit for potential harm to bone and tissue. Numerical models were employed to validate and corroborate the findings, which exhibited identical outcomes when applied to genuine bone samples with distinct thermal characteristics.

Cooling Efficiency of Sleeveless 3D-Printed Surgical Guides with Different Cylinder Designs

Background and Objectives: Surgical guides might impede the flow of coolant to the implant drills during the preparation of the implant bed, potentially contributing to increased temperatures during bone drilling. The objective of this experimental study was to assess the cooling efficiency of various guiding cylinder designs for sleeveless surgical guides used in guided surgery. Materials and Methods: In this experimental study, surgical guides with three different guiding cylinder designs were printed. One group had solid cylinders (control) and two test groups (cylinders with pores and cylinders with windows). Forty customized polyurethane blocks with type III bone characteristics were fitted into the guide and fixed in a vise, and implant bed preparations were completed using a simplified drilling protocol with and without irrigation. An infrared thermographic camera was used to record the temperature changes during drilling at the coronal, middle, and apical areas. ANOVA test and Games-Howell post hoc test were used to determine significant thermal differences among groups. Results: A significant thermal increase was observed at the coronal area in the group without irrigation (39.69 ± 8.82) (p < 0.05). The lowest thermal increase was recorded at the surgical guides with windows (21.451 ± 0.703 °C) compared to solid (25.005 ± 0.586 °C) and porous surgical guides (25.630 ± 1.004) (p < 0.05). In the middle and apical areas, there were no differences between solid and porous cylinders (p > 0.05). Conclusions: 3D-printed sleeveless surgical guides with window openings at the guiding cylinders reduce the temperature elevation at the cortical bone in guided implant surgery.

The 3D Printing and Evaluation of Surgical Guides with an Incorporated Irrigation Channel for Dental Implant Placement

Dental implant insertion requires the preparation of the implant bed via surgical drilling. During this stage, irrigation is essential to avoid thermal damage to the surrounding bone. Surgical guides enhance the accuracy of the implant site preparation, but they mask the drilling site, hampering coolant delivery. A variety of designs are aimed at improving the coolant access to the target site. Using standard dental implant simulation software, this paper presents an in-house design and 3D printing workflow for building surgical guides that incorporate a coolant channel directed toward the entry point of the burr. The proposed design was evaluated in terms of the bone temperature elevations caused by drilling performed at 1500 rpm, under an axial load of 2 kg, and irrigation with 40 mL/min of saline solution at 25 °C. Temperature measurements were performed on porcine femoral pieces, in the middle of the cortical bone layer, at 1 mm from the edge of the osteotomy. The mean temperature rise was 3.2 °C for a cylindrical sleeve guide, 2.7 °C for a C-shaped open-sleeve guide, and 2.1 °C for the guide with an incorporated coolant channel. According to a one-way ANOVA, the differences between these means were marginally insignificant (p = 0.056). The individual values of the peak temperature change remained below the bone damage threshold (10 °C) in all cases. Remarkably, the distribution of the recorded temperatures was the narrowest for the guide with internal irrigation, suggesting that, besides the most effective cooling, it provides the most precise control of the intraosseous temperature. Further studies could test different design variants, experimental models (including live animals), and might involve computer simulations of the bone temperature field.