In vitro evaluation of bioburden, three-dimensional stability, and accuracy of surgical templates without metallic sleeves after routinely infection control activities

The three-dimensional stability and accuracy of 3D printing surgical templates: An In Vitro study

OBJECTIVE

To evaluate the three-dimensional (3D) stability and accuracy of additively manufactured surgical templates fabricated using two different 3D printers and materials.

MATERIALS AND METHODS

Forty surgical templates were designed and printed using two different 3D printers: the resin group (n = 20) used a digital light processing (DLP) 3D printer with photopolymer resin, and the metal group (n = 20) employed a selective laser melting (SLM) 3D printer with titanium alloy. All surgical templates were scanned immediately after production and re-digitalized after one month of storage. Similarly, the implant simulations were performed twice. Three-dimensional congruency between the original design and the manufactured surgical templates was quantified using the root mean square (RMS), and the definitive and planned implant positions were determined and compared.

RESULTS

At the postproduction stage, the metal templates exhibited higher accuracy than the resin templates (p < 0.001), and these differences persisted after one month of storage (p < 0.001). The resin templates demonstrated a significant decrease in three-dimensional stability after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05). No significant differences in implant accuracy were found between the two groups. However, the resin templates showed a significant increase in apical and angular deviations after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05).

CONCLUSION

Printed metal templates showed higher fabrication accuracy than printed resin templates. The three-dimensional stability and implant accuracy of printed metal templates remained unaffected by one month of storage.

CLINICAL SIGNIFICANCE

With superior three-dimensional stability and acceptable implant accuracy, printed metal templates can be considered a viable alternative technique for guided 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.

Advancing accuracy in guided implant placement: A comprehensive meta-analysis: Meta-Analysis evaluation of the accuracy of available implant placement Methods

OBJECTIVES

This meta-analysis aimed to determine the accuracy of currently available computer-assisted implant surgery (CAIS) modalities under in vitro conditions and investigate whether these novel techniques can achieve clinically acceptable accuracy.

DATA

In vitro studies comparing the postoperative implant position with the preoperative plan were included. Risk of bias was assessed using the Quality Assessment Tool For In Vitro Studies (QUIN Tool) and a sensitivity analysis was conducted using funnel plots.

SOURCES

A systematic search was performed on April 18, 2023, using the following three databases: MEDLINE (via PubMed), EMBASE, and Cochrane Central Register of Controlled Trials. No filters or restrictions were applied during the search.

RESULTS

A total of 5,894 studies were included following study selection. Robotic- and static CAIS (sCAIS) had the most accurate and clinically acceptable outcomes. sCAIS was further divided according to the guidance level. Among the sCAIS groups, fully guided implant placement had the greatest accuracy. Augmented reality-based CAIS (AR-based CAIS) had clinically acceptable results for all the outcomes except for apical global deviation. Dynamic CAIS (dCAIS) demonstrated clinically safe results, except for horizontal apical deviation. Freehand implant placement was associated with the greatest number of errors.

CONCLUSIONS

Fully guided sCAIS demonstrated the most predictable outcomes, whereas freehand sCAIS demonstrated the lowest accuracy. AR-based and robotic CAIS may be promising alternatives.

CLINICAL SIGNIFICANCE

To our knowledge, this is the first meta-analysis to evaluate the accuracy of robotic CAIS and investigate the accuracy of various CAIS modalities.

A survey regarding the organizational aspects and quality systems of in-house 3D printing in oral and maxillofacial surgery in Germany

PURPOSE

The aim of the study was to get a cross-sectional overview of the current status of specific organizational procedures, quality control systems, and standard operating procedures for the use of three-dimensional (3D) printing to assist in-house workflow using additive manufacturing in oral and maxillofacial surgery (OMFS) in Germany.

METHODS

An online questionnaire including dynamic components containing 16-29 questions regarding specific organizational aspects, process workflows, quality controls, documentation, and the respective backgrounds in 3D printing was sent to OMF surgeons in university and non-university hospitals as well as private practices with and without inpatient treatment facilities. Participants were recruited from a former study population regarding 3D printing; all participants owned a 3D printer and were registered with the German Association of Oral and Maxillofacial Surgery.

RESULTS

Sixty-seven participants answered the questionnaires. Of those, 20 participants ran a 3D printer in-unit. Quality assurance measures were performed by 13 participants and underlying processes by 8 participants, respectively. Standard operating procedures regarding computer-aided design and manufacturing, post-processing, use, or storage of printed goods were non-existent in most printing units. Data segmentation as well as computer-aided design and manufacturing were conducted by a medical doctor in most cases (n = 19, n = 18, n = 8, respectively). Most participants (n = 8) stated that "medical device regulations did not have any influence yet, but an adaptation of the processes is planned for the future."

CONCLUSION

The findings demonstrated significant differences in 3D printing management in OMFS, especially concerning process workflows, quality control, and documentation. Considering the ever-increasing regulations for medical devices, there might be a necessity for standardized 3D printing recommendations and regulations in OMFS.

The microbiological effect of virgin coconut oil on the morphological and volumetric dimensional changes of 3D printed surgical guides (in vitro study)

BACKGROUND/OBJECTIVES

Disinfection of surgical guides is mandatory for intraoperative use. Virgin Coconut Oil may be a potent alternative disinfectant; however, its effect has not been fully discussed in dentistry. The objectives of this study were to compare the morphological and the volumetric dimensional changes of 3D printed surgical guides after immersion in three disinfectants: 100%Virgin Coconut Oil, 2% Glutaraldehyde, and 70% Ethyl Alcohol and to assess the antimicrobial effectiveness of the tested disinfectants.

MATERIALS AND METHODS

A surgical guide was designed using open platform software to print thirty guides and then cut them into two halves (N = 60). Pre-disinfection scans of the first half of the three study groups (n = 30) were performed using Cone-beam Computed Tomography, then immersed for 20 min in three disinfectants as follows: group VCO was immersed in 100% Virgin Coconut Oil, group GA was immersed in 2% Glutaraldehyde, and group EA was immersed in 70% Ethyl Alcohol. Post-disinfection scans of the first half of the three study groups (n = 30) were performed and then compared morphologically and volumetrically using an analyzing software program The second half of the three control groups (n* = 30) were soaked for 20 min in sterile distilled water as follows: group VCO*, group GA*, and group EA* for the assessment of the antimicrobial effectiveness of the three tested disinfectants.

RESULTS

At the morphological assessment of the dimensional changes, group VCO were the most accurate with the lowest mean deviation value of 0.12 ± 0.02 mm and root mean square value of 0.12 mm, group GA and group EA were less accurate with mean deviation value of = 0.22 ± 0.05 mm and = 0.19 ± 0.03 mm and root mean square value of 0.22 and 0.20 respectively (p < 0.001). At the volumetric assessment, group VCO showed lower volumetric changes with a mean deviation value of 0.17 ± 0.10 mm, root mean square value of 0.19 mm, than group GA with mean deviation value of 0.23 ± 0.10 mm, root mean square value of 0.25 mm and group EA with mean deviation value of 0.27 ± 0.11 mm, root mean square value of 0.29 mm, however, no statistically significant differences were found between the three study groups (p = 0.10). The antimicrobial effectiveness of the three tested disinfectants showed a hundred percent (100%) reduction in the total microbial count in the first half of the three study groups treated with the three disinfectants revealing no bacterial growth, however, statistically significant differences were found between the second half of the three control and the first half of the three study groups. (p < 0.001).

CONCLUSIONS

Virgin Coconut Oil showed higher morphological dimensional accuracy of the tested surgical guides than Glutaraldehyde and Ethyl Alcohol without causing any volumetric dimensional changes in the 3D printed surgical guides after disinfection for 20 min and the antimicrobial effectiveness was the same between the three tested disinfectants without showing any microbial growth.

Digital Workflow for Prosthetically Driven Implants Placement and Digital Cross Mounting: A Retrospective Case Series

Fully digital workflow in implant dentistry is ever increasing. Treatment of partial edentulous cases is well-documented; nevertheless, complete edentulous cases are still a challenge. To present several innovations in the treatment of complete edentulous patients using digital solutions, both for implant placement and restoration delivery, was the objective of this study. It was designed as a retrospective case series study, aimed to tune further research with larger sample size, and a longer follow-up. Patients requiring complete, implant-supported restoration were asked to participate in this study. Enrolled patients were treated with four implants, immediate loading and a definitive complete arch restoration. Patients were treated using computer-assisted, template-based surgery. Multi-piece surgical templates were used to accurately place the implants, to manage the bone if needed and to make immediate loading procedure quicker and easier. After osseointegration period, definitive, extra-oral, digital impressions were taken using newly developed scan analogs, connected in the patient mouth using temporary cylinders and stabilized by means of the low-shrinkage, flowable, resin composite. Outcomes were implant and prosthesis survival rate, complications, accuracy, and patient satisfaction. Radiographic evaluation performed with a preliminary, radiopaque aluminum try-in, was used to test the accuracy of the digital impressions. Overall, 20 implants were placed in five patients. All the implants osseointegrated without complications. One impression was taken a second time due to inaccuracy of the aluminum tray-in. Finally, all of the patients were completely satisfied with both surgical and prosthetic procedures. Within the limitations of this case series, multi-piece surgical templates showed promising results improving the clinician’s confidence in the case of bone reduction, post-extractive implants and immediate loading. The prosthetic template increased the trueness of the digital impression for complete edentulous patients. Finally, even if an impression was performed again, the scan-analog used for extra-oral chair-side digital impressions seemed to be a promising tool. Continuous improvements and further study are needed to confirm these preliminary results.

Impact of Steam Autoclaving on the Mechanical Properties of 3D-Printed Resins Used for Insertion Guides in Orthodontics and Implant Dentistry

Guided implant placement has been shown to be more accurate than free-handed insertion. Still, implant position deviations occur and could possibly pose risks. Thus, there is a quest to identify factors that might impair the accuracy of implantation protocols using templates. This study aimed to investigate the influence of autoclaving cycles (cycle 1: 121 °C, 1 bar, 20.5 min; cycle 2: 134 °C, 2 bar, 5.5 min) on the Vickers hardness and flexural modulus of five different materials used for 3D-printed insertion guides. The specimens were subjected to Vickers hardness tests, showing significant changes in the Vickers hardness for two and three materials out of five for cycle 1 and 2, respectively. The results of the three-point bending tests (n = 15 specimens per material) showed decreasing flexural moduli after autoclaving. However, changes were significant only for one material, which presented a significant decrease in the flexural modulus after cycle 2. No significant changes were detected after cycle 1. In conclusion, our findings show that autoclaving can alter the mechanical properties of the templates to some extent, especially with cycle 2. Whether these modifications are associated with dimensional changes of the templates and reduced accuracy of the implantation protocols remains to be investigated.