Thermal exposure of implant osteotomies and its impact on osseointegration-A preclinical in vivo study

Correlation between intraosseous thermal change and drilling impulse data during osteotomy within autonomous dental implant robotic system: An in vitro study

OBJECTIVES

This study aims at examining the correlation of intraosseous temperature change with drilling impulse data during osteotomy and establishing real-time temperature prediction models.

MATERIALS AND METHODS

A combination of in vitro bovine rib model and Autonomous Dental Implant Robotic System (ADIR) was set up, in which intraosseous temperature and drilling impulse data were measured using an infrared camera and a six-axis force/torque sensor respectively. A total of 800 drills with different parameters (e.g., drill diameter, drill wear, drilling speed, and thickness of cortical bone) were experimented, along with an independent test set of 200 drills. Pearson correlation analysis was done for linear relationship. Four machining learning (ML) algorithms (e.g., support vector regression [SVR], ridge regression [RR], extreme gradient boosting [XGboost], and artificial neural network [ANN]) were run for building prediction models.

RESULTS

By incorporating different parameters, it was found that lower drilling speed, smaller drill diameter, more severe wear, and thicker cortical bone were associated with higher intraosseous temperature changes and longer time exposure and were accompanied with alterations in drilling impulse data. Pearson correlation analysis further identified highly linear correlation between drilling impulse data and thermal changes. Finally, four ML prediction models were established, among which XGboost model showed the best performance with the minimum error measurements in test set.

CONCLUSION

The proof-of-concept study highlighted close correlation of drilling impulse data with intraosseous temperature change during osteotomy. The ML prediction models may inspire future improvement on prevention of thermal bone injury and intelligent design of robot-assisted implant surgery.

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.

Influence of drilling sequence and guide-hole design on the accuracy of static computer-assisted implant surgery in extraction sockets and healed sites-An in vitro investigation

OBJECTIVES

To evaluate the effect of drilling sequence, guide-hole design, and alveolar ridge morphology on the accuracy of implant placement via static computer-assisted implant surgery (sCAIS).

MATERIALS AND METHODS

Standardized maxillary bone models including single-tooth gaps with fresh extraction sockets or healed alveolar ridge morphologies were evaluated in this study. Implants were placed using different drilling sequences (i.e., complete [CDS] or minimum [MDS]), and guide-hole designs (i.e., manufacturer's sleeve [MS] or sleeveless [SL] guide-hole designs). The time for implant placement via sCAIS procedures was also recorded. The angular, crestal, and apical three-dimensional deviations between planned and final implant positions were digitally obtained. Statistical analyses were conducted by a non-parametric three-way ANOVA (α = .05).

RESULTS

Based on a sample size analysis, a total of 72 implants were included in this study. Significantly higher implant position accuracy was found at healed sites compared to extraction sockets and in SL compared to MS guide-hole design in angular, crestal, and apical 3D deviations (p ≤ .048). A tendency for higher accuracy was observed for the CDS compared to the MDS, although the effect was not statistically significant (p = .09). The MDS required significantly shorter preparation times compared with CDS (p < .0001).

CONCLUSION

Implant placement via sCAIS resulted in higher accuracy in healed sites than extraction sockets, when using SL compared to MS guides, and tended to be more accurate when using CDS compared to MDS. Therefore, even though surgery time was shorter with MDS, its use should be limited to strictly selected cases.

Drilling- and withdrawing-related thermal effects of implant site preparation for ceramic and stainless steel twist drills in standardized bovine bone

INTRODUCTION

Excessive surgical trauma is believed to be among the most important causes for early implant losses. As thermal injury to the bone is not only dependent on the amount of generated heat but also on the tissue exposure time, and the greatest temperature increase was found within the withdrawing period, the entire osteotomy procedure with the parameters contributing to thermal damage is of particular clinical relevance. The aim of this study was to investigate the thermal performance of metal-based and ceramic implant drills regarding the temperature exposure time during the whole osteotomy process.

MATERIALS AND METHODS

This investigation consisted of 240 individual preparations in total, comprising two different drilling depths (10 and 16 mm), two irrigation methods (external and without irrigation), two implant drill materials (stainless steel and zirconia), and three consecutive drill diameters per material (2.0/2.2, 2.8, and 3.5 mm) with 10 identical repetitions. Real-time multichannel temperature measurement was conducted during automated drilling procedures in standardized bovine bone specimens.

RESULTS

The maximum temperature changes were highly associated with the time period of passive drill withdrawing (p ≤ 0.05), irrespective of drill material, drilling depth, or drill diameter. Statistically significant differences in temperature generation between stainless steel and ceramic drills were observed in irrigated testing sites at both drilling depths with smaller drill diameters (2.0/2.2 and 2.8 mm, p ≤ 0.05).

CONCLUSION

Results of this in vitro study could demonstrate a strong association between the highest temperature increase and the passive withdrawing time period in both investigated drill materials. Considering these findings and the resulting thermal bone damage due to the whole surgical procedure, high overall temperatures in combination with a prolonged heat exposure time may impact the future osseointegration process.