Registration of cone beam computed tomography data and intraoral surface scans - A prerequisite for guided implant surgery with CAD/CAM drilling guides

Accuracy of two static computer-assisted implant surgery systems in partially edentulous patients: a randomized clinical trial using intraoral scan data

OBJECTIVES

To compare implant deviations between two static computer-assisted implant surgery (sCAIS) systems in partially edentulous patients using intraoral scan data.

METHODS

Fully guided dental implant placements were planned using two implant systems, Straumann Bone Level Tapered (S-BLT) and CAMLOG SCREW LINE Promote plus (C-SL), with respective planning software (S-BLT: coDiagnostiX; C-SL: SMOP). Intraoperative scans were performed after implant placement and compared to virtual implant positions in Geomagic Control X (GCX) a software for three-dimensional (3D) quality control. Deviations were analyzed in a coordinate system (x-, y-, z-axis) and total deviations (entry point, apex, and angular deviations) were compared. Statistical significance was set at p<0.0125.

RESULTS

Sixty-nine patients received 80 implants placed by 13 surgeons with varying experience in sCAIS. Deviations from 75 datasets were evaluated. Mean 3D deviation at the entry point was 0.64 ±0.25mm for S-BLT and 0.75 ±0.33mm for C-SL. At the apex, the mean 3D deviation was 1.00 ±0.40mm for S-BLT and 1.26 ±0.68mm for C-SL. The mean angular deviation was 3.22 ±2.12° for S-BLT and 3.80 ±2.81° for C-SL. No significant differences were observed between systems, surgeon experience or implant location (all p>0.0125).

CONCLUSIONS

Both the drill-body guided (C-SL) and drill-handle guided (S-BLT) systems provide comparable and predictable outcomes in fully guided implant placements. No system or planning software was found to be superior.

CLINICAL SIGNIFICANCE

sCAIS ensures predictable results in terms of accuracy in implant positioning, compensating for varying levels of surgical experience.

Accuracy of robotic computer-assisted implant surgery in clinical studies: a systematic review and meta-analysis

OBJECTIVES

To analyze the accuracy of the robotic system in clinical studies and assess potential factors that might affect the accuracy of robotic implant placement.

MATERIALS AND METHODS

PubMed, Embase, and Cochrane Central Register of Controlled Trials were used to search for studies published from August 2014 till October 2024. Studies on robotic computer-assisted implant surgery (R-CAIS) were identified. Furthermore, manual searches were performed for selected journals. Only clinical studies were included. Subgroup analysis was performed based on robot autonomy, different dentitions, and the working principle of the camera.

RESULTS

Sixteen studies met the inclusion criteria, evaluating 908 implants. The meta-analysis of accuracy showed that the average global platform deviation, global apex deviation, and angular deviation were 0.69 mm (95% CI: 0.61‒0.77, I2 = 94%), 0.72 mm (95% CI: 0.64‒0.79, I2 = 93%), and 1.62° (95% CI: 1.34°‒1.89°, I2 = 96%), respectively. In subgroup analysis, Meta-generic inverse variance analysis observed statistically significant differences in global platform deviation and apex deviation between robots using infrared and mechanical tracking (p < 0.01), as well as between those using visible light and mechanical tracking (p < 0.01). No significant differences were observed between autonomous and semi-active systems and different dentitions.

CONCLUSION

The R-CAIS technology demonstrated a high level of accuracy. However, further large-scale, multi-center, randomized, controlled clinical trials are necessary to compare robotic implant placement with other techniques, and the additional factors influencing robotic implant placement must be explored.

Comparison Between Conventional and Artificial Intelligence-Assisted Setup for Digital Implant Planning: Accuracy, Time-Efficiency, and User Experience

OBJECTIVES

To investigate the reliability and time efficiency of the conventional compared to the automatic artificial intelligence (AI) segmentation of the mandibular canal and registration of the CBCT with the model scan data, in relation to clinician's experience.

MATERIALS AND METHODS

Twenty clinicians, 10 with a moderate and 10 with a high experience in computer-assisted implant planning, were asked to perform a bilateral localization of the mandibular canal, followed by a registration of the intraoral model scan with the CBCT. Subsequently, for each data set and each participant, the same operations were performed utilizing the AI tool. Statistical significance was assessed via a mixed model (using the PROC MIXED statement and the compound symmetry covariance structure).

RESULTS

The mean time for the segmentation of the mandibular canals and the registration of the models was 4.75 (2.03)min for the manual and 2.03 (0.36) min for the AI-automated operations (p < 0.001). The mean discrepancy in the mandibular canals was 0.71 (1.80) mm RMS error for the manual segmentation and 0.68 (0.36) RMS error for the AI-assisted segmentation (p > 0.05). For the registration between the CBCT and the intraoral scans, the mean discrepancy was 0.45 (0.16) mm for the manual and 0.37 (0.07) mm for the AI-assisted superimposition (p > 0.05).

CONCLUSIONS

AI-automated implant planning tools are feasible options that can lead to a similar or better accuracy compared to the conventional manual workflow, providing improved time efficiency for both experienced and less experienced users. Further research including a variety of software and data sets is required to be able to generalize the outcomes of the present study.

An AI-based tool for prosthetic crown segmentation serving automated intraoral scan-to-CBCT registration in challenging high artifact scenarios

STATEMENT OF PROBLEM

Accurately registering intraoral and cone beam computed tomography (CBCT) scans in patients with metal artifacts poses a significant challenge. Whether a cloud-based platform trained for artificial intelligence (AI)-driven segmentation can improve registration is unclear.

PURPOSE

The purpose of this clinical study was to validate a cloud-based platform trained for the AI-driven segmentation of prosthetic crowns on CBCT scans and subsequent multimodal intraoral scan-to-CBCT registration in the presence of high metal artifact expression.

MATERIAL AND METHODS

A dataset consisting of 30 time-matched maxillary and mandibular CBCT and intraoral scans, each containing at least 4 prosthetic crowns, was collected. CBCT acquisition involved placing cotton rolls between the cheeks and teeth to facilitate soft tissue delineation. Segmentation and registration were compared using either a semi-automated (SA) method or an AI-automated (AA). SA served as clinical reference, where prosthetic crowns and their radicular parts (natural roots or implants) were threshold-based segmented with point surface-based registration. The AA method included fully automated segmentation and registration based on AI algorithms. Quantitative assessment compared AA's median surface deviation (MSD) and root mean square (RMS) in crown segmentation and subsequent intraoral scan-to-CBCT registration with those of SA. Additionally, segmented crown STL files were voxel-wise analyzed for comparison between AA and SA. A qualitative assessment of AA-based crown segmentation evaluated the need for refinement, while the AA-based registration assessment scrutinized the alignment of the registered-intraoral scan with the CBCT teeth and soft tissue contours. Ultimately, the study compared the time efficiency and consistency of both methods. Quantitative outcomes were analyzed with the Kruskal-Wallis, Mann-Whitney, and Student t tests, and qualitative outcomes with the Wilcoxon test (all α=.05). Consistency was evaluated by using the intraclass correlation coefficient (ICC).

RESULTS

Quantitatively, AA methods excelled with a 0.91 Dice Similarity Coefficient for crown segmentation and an MSD of 0.03 ±0.05 mm for intraoral scan-to-CBCT registration. Additionally, AA achieved 91% clinically acceptable matches of teeth and gingiva on CBCT scans, surpassing SA method's 80%. Furthermore, AA was significantly faster than SA (P<.05), being 200 times faster in segmentation and 4.5 times faster in registration. Both AA and SA exhibited excellent consistency in segmentation and registration, with ICC values of 0.99 and 1 for AA and 0.99 and 0.96 for SA, respectively.

CONCLUSIONS

The novel cloud-based platform demonstrated accurate, consistent, and time-efficient prosthetic crown segmentation, as well as intraoral scan-to-CBCT registration in scenarios with high artifact expression.

Accuracy of static computer-aided implant surgery (S-CAIS) using CAD-CAM surgical templates fabricated from different additive manufacturing technologies

STATEMENT OF PROBLEM

Different 3D printers are available for guided implant surgery, but studies that evaluate their source of errors and their cost-effectiveness are lacking.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of different 3-dimensional (3D) printed surgical templates made using different additive manufacturing technologies and to evaluate the effect of implant location on the accuracy of fully guided implant placement.

MATERIAL AND METHODS

Fifty partially edentulous maxillary typodonts with edentulous sites in the right second premolar (SP), right lateral incisor (LI), left central incisor (CI), and left first molar (FM) locations were scanned and printed from the standard tessellation language (STL) datasets. The study compared 5 groups for the fabrication of implant surgical templates: Varseo S-Bego (Bego), Polyjet-Stratasys (Poly), Low Force Stereolithography-FormLabs (LFS), P30+-Straumann (P30), and M2-Carbon (M2). After fully guided implant placement, the typodont was scanned, and the 3D implant positions were compared with the master model by superimposing the STL files. Descriptive statistics were calculated for groups and subgroups, and comparisons among the groups and subgroups were conducted via 2-way mixed analysis of variance, Tukey honest significant difference, and post hoc Bonferroni tests (α=.05).

RESULTS

The results were site specific and not consistent within each group. For angle deviation, the within-group analysis for P30 demonstrated significantly lower values for implants positioned at site SP (1.4 ±0.8 degrees) than for sites LI (2.3 ±0.7 degrees; P=.001) and CI (2.3 ±0.8 degrees; P=.007). For 3D offset at base for implant CI, LFS was significantly higher than Bego (P=.002), Poly (P=.035), or M2 (P=.001); P30 was also significantly higher than Bego (P=.014) and M2 (P=.006). LFS had a significantly higher 3D offset at the tip than Bego (P=.001) and M2 (P=.022) for implant CI.

CONCLUSIONS

The choice of 3D printer seemed to influence fully guided implant surgery in terms of the final implant position compared with initial implant planning. However, although statistically significant differences were present across groups, all additive manufacturing technologies were within clinically acceptable values.

Automated dental registration and TMJ segmentation for virtual surgical planning of orthognathic surgery via three-step computer-based method

OBJECTIVE

This study developed and evaluated a computer-based method for automating the registration of scanned dental models with 3D reconstructed skulls and segmentation of the temporomandibular joint (TMJ).

METHODS

A dataset comprising 1274 skull models and corresponding scanned dental models was collected. In total, 1066 cases were used for the development of the computer-based method, while 208 cases were used for validation. Performance was evaluated by comparing the automated results with manual registration and segmentation performed by clinicians, using accuracy and completeness metrics (e.g. intersection of union [IoU] and Dice similarity coefficient [DSC]).

RESULTS

The automated registration achieved a mean absolute error of 0.35 mm for the maxilla and 0.38 mm for the mandible, and a root mean squared error of 0.46 mm and 0.39 mm, respectively. The automatic TMJ segmentation exhibited an accuracy of 97.48 %, a precision of 97.06 %, a IoU of 95.72 %, DSC of 97.3 %, and a Hausdorff value of 1.87 mm, which were sufficient for clinical application.

CONCLUSION

The proposed method significantly improved the efficiency of orthognathic surgical planning by automating the registration and segmentation processes. The accuracy and precision of the automated results were sufficient for clinical use, reducing the workload on clinicians and facilitating faster and more reliable surgical planning.

CLINICAL SIGNIFICANCE

The computer-based method streamlines orthognathic surgical planning, enhancing precision and efficiency without compromising clinical accuracy, ultimately improving patient outcomes and reducing the workload of surgeons.

Effect of fabrication methods and number of supporting teeth on the surface accuracy and dimensional stability of implant surgical guides

STATEMENT OF PROBLEM

Implant surgical guides manufactured using different fabrication methods have been commonly used for computer-guided implant placement. However, how fabrication methods and the number of supporting teeth influence accuracy and stability remains uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of fabrication methods and number of supporting teeth on the surface accuracy and dimensional stability of implant surgical guides with 3 different 3-dimensional (3D) printers and 1 computer numeric controlled (CNC) milling machine.

MATERIAL AND METHODS

Two tooth-supported maxillary implant surgical guides with different number of supporting teeth (S: short span with 4 supporting teeth, L: long span with complete arch supporting) were used to fabricate the specimens. Eighty surgical guides were fabricated from 3 different 3D printers and 1 milling machine as follows: group SLA-S (n=10) and SLA-L (n=10) were fabricated with a desktop stereolithography (SLA) 3D printer and photopolymerizing resin; group PolyJet-S (n=10) and PolyJet-L (n=10) were fabricated with a PolyJet 3D printer and photopolymerizing resins; group DLP-S (n=10) and DLP-L (n=10) were fabricated with a desktop digital light processing (DLP) 3D printer and photopolymerizing resin; and group MILL-S (n=10) and group MILL-L (n=10) were fabricated with a 5-axis milling machine and polymethyl methacrylate (PMMA) blanks. All surgical guides were digitized immediately after postprocessing and after 1, 2, and 3 months using a desktop scanner. The congruency between design files and digitized files was quantified with the root mean square (RMS) error with a metrology program (Geomagic Control X). Two-way ANOVA was used to analyze trueness, and the Levene test was used to assess precision (α=.05).

RESULTS

The fabrication methods and number of supporting teeth significantly affected the surface trueness of the guide (P<.001). Milled guides had the lowest mean RMS value for surface trueness, 45 µm for guides with 4 supporting teeth and 59 µm for guides with complete arch supporting. Regarding precision, the Levene test revealed significant difference among fabrication methods (P<.05), while no significant difference was found in the same fabrication method group (P>.05). After 3 months of storage, RMS values increased significantly in the complete arch supporting group comparison of SLA, PolyJet, and DLP (P<.001, P<.001, and P=.015, respectively). RMS values remained similar in other groups.

CONCLUSIONS

The trueness and dimensional stability of the surface of the implant surgical guides were affected by fabrication methods and the number of supporting teeth. However, the precision was only affected by fabrication methods. Milled surgical guides showed higher accuracy and better dimensional stability after storage than those produced with 3D printers. Among the groups of 3D printing, guides with 4 supporting teeth showed higher trueness and a lower degree of deformation after storage.

Automatic multimodal registration of cone-beam computed tomography and intraoral scans: a systematic review and meta-analysis

OBJECTIVES

To evaluate recent advances in the automatic multimodal registration of cone-beam computed tomography (CBCT) and intraoral scans (IOS) and their clinical significance in dentistry.

METHODS

A comprehensive literature search was conducted in October 2024 across the PubMed, Web of Science, and IEEE Xplore databases, including studies that were published in the past decade. The inclusion criteria were as follows: English-language studies, randomized and nonrandomized controlled trials, cohort studies, case-control studies, cross-sectional studies, and retrospective studies.

RESULTS

Of the 493 articles identified, 22 met the inclusion criteria. Among these, 14 studies used geometry-based methods, 7 used artificial intelligence (AI) techniques, and 1 compared the accuracy of both approaches. Geometry-based methods primarily utilize two-stage coarse-to-fine registration algorithms, which require relatively fewer computational resources. In contrast, AI methods leverage advanced deep learning models, achieving significant improvements in automation and robustness.

CONCLUSIONS

Recent advances in CBCT and IOS registration technologies have considerably increased the efficiency and accuracy of 3D dental modelling, and these technologies show promise for application in orthodontics, implantology, and oral surgery. Geometry-based algorithms deliver reliable performance with low computational demand, whereas AI-driven approaches demonstrate significant potential for achieving fully automated and highly accurate registration. Future research should focus on challenges such as unstable registration landmarks or limited dataset diversity, to ensure their stability in complex clinical scenarios.

Evaluation of gingival thickness obtained from intraoral scanning registration with cone beam computed tomography at different acquisition modes

OBJECTIVES

To investigate the reliability of gingival thickness measurements obtained from the registration of intraoral scans with cone beam computed tomography (CBCT) examinations at different acquisition modes.

STUDY DESIGN

CBCT examinations of 9 porcine hemimandibles were acquired using the OP300 Maxio unit operating at the highest-dose protocol with the smallest voxel size as the reference standard for visualizing the gingival surface. Subsequently, the hemimandibles were surrounded by water to simulate soft tissue attenuation of radiation, and additional CBCT examinations were acquired in 4 modes: Endo, High-resolution, Standard-resolution, and Low-dose. These CBCT datasets were registered with corresponding intraoral scans obtained with the Carestream Dental 3600 intraoral scanning system using the Blue Sky Plan 4 software. Four oral radiologists measured the buccal gingival thickness on cross-sectional reconstructions at 4 measurement sites and 2 distances from the gingival margin in the CBCT reference standard examinations and examinations obtained with water and intraoral scan registration. Multifactorial analysis of variance was used to assess the influence of acquisition mode, measurement site, and distance from the gingival margin on measurements (α = 5%; statistical power = 90%).

RESULTS

Buccal gingival thickness measurements obtained via CBCT after registration with intraoral scanning were not significantly influenced by acquisition mode (P = .153) or measurement site (P = .089).

CONCLUSIONS

Gingival thickness measurements derived from the registration of intraoral scans with CBCT examinations at different acquisition modes appear to be reliable.

Contemporary Digital Dentistry for Complex Cases in the Anterior Maxilla

OBJECTIVES

To demonstrate how contemporary digitally driven workflow can enhance outcomes for complex esthetic dental cases, focusing on three distinct clinical scenarios involving implant placement, esthetic crown lengthening, and tooth autotransplantation (ATT).

OVERVIEW

Three multidisciplinary clinical cases demonstrate our contemporary digital workflows, integrating diagnosis, treatment planning, patient communication, and guided execution. The first case involves replacing two anterior central incisors using digital planning, guided surgery, prefabricated customized healing abutments, and a digitally driven restorative process. The second case showcases an esthetic crown-lengthening procedure, where Multifunctional Anatomical Prototypes (MAPs) serve as both mock-up and surgical guides, enhancing patient communication on expected outcomes and ensuring precise tissue management to prevent soft tissue rebound. The final case features a tooth ATT, where virtual surgical planning and 3D-printed tooth replica and guides ensure predictability in the therapeutic outcome. These digitally enabled strategies underscore the predictability and customization achievable with contemporary dental technology.

CONCLUSIONS

Dental treatments in the esthetic zone require meticulous planning and precise execution to achieve controlled results that ensure patient satisfaction and long-term stability. Contemporary Digital Dentistry enhances predictability, creating a pathway that leads to success.

Effect of Storage Conditions and Time on the Dimensional Stability of 3D Printed Surgical Guides: An In Vitro Study

PURPOSE

To evaluate the dimensional stability over time of additively manufactured surgical templates, fabricated by different resins, and stored by different methods.

MATERIALS AND METHODS

Using a 3D printer with DLS technology and two different resins (Surgical Guide (SG)-WhipMix and Key Guide (KG)-KeystoneIndustries), 96 surgical guides were additively manufactured. The guides were stored in three different environments: directly exposed to sunlight (S1), in normal interior room conditions (S2), and in darkness (S3). The guides were digitally scanned immediately after fabrication and post-processing, and after 1, 3, and 6 months of storage. For each group, the mean deviation of the root mean square (RMS) between guide's intaglio surface, as well as the axial deviation between sleeves' housings were calculated.

RESULTS

The mean axial variations of angular axis deviation of sleeves' housings ranged between 0.09° and 3.99°. The mean deviation of the RMS discrepancy in guide's intaglio ranged from 0.1 to 0.18 mm. Variations were significant (p < 0.001) only for the S1 group and only for SG material. After 3 months, an additional storage time of 3 months did not have any further effect on dimensional stability.

CONCLUSIONS

Within the limitations of the present study, storage time of a surgical guide for up to 3 months after manufacturing, as well as printing material can significantly affect surgical guide's dimensional stability, when they are exposed to direct or indirect sunlight conditions. Storage of guides in a dark environment is recommended in order to avoid an additional source of error in computer-guided surgery workflows.

An in vitro study of a combined patient-specific device for safe and accurate insertion of infrazygomatic crest miniscrews

OBJECTIVES

To develop and assess the efficacy of a novel combined patient-specific device (CPSD) for the accurate and safe insertion of infrazygomatic crest miniscrews in orthodontic procedures.

MATERIALS AND METHODS

Twenty-eight miniscrews were placed in the infrazygomatic crest region of 28 cadaver maxillae using the direct manual method (n = 14) or the CPSD (n = 14) based on preset trajectories. The CPSD, designed based on the integration model, included a positioning guide, an insertion guide, and a depth-limiting groove. Deviations in the insertion site, tip location, insertion angle, and biting depth between the preset and real insertion trajectories were calculated to evaluate the accuracy of miniscrew insertion. Classification frequencies of root proximity, sinus penetration depth, and biting depth of the miniscrew after insertion were also calculated to evaluate the safety of miniscrew insertion.

RESULTS

Regarding evaluation of accuracy, significant differences were observed in the deviation values of the insertion site, tip location, insertion angle, and biting depth between the CPSD and freehand groups (P = .001, P < .001, P < .001, P = .039, respectively). Regarding evaluation of safety, a significant difference was observed in the classification frequencies of root proximity between the two groups (P = .016).

CONCLUSIONS

Compared with manual insertion, CPSD could be a preferred method for safe and accurate insertion of infrazygomatic crest miniscrews for orthodontists.

Single scanning of CBCT and intraoral scanning for guided implantation in terminal dentitions with multi-unit metal restorations: technical note

When anatomical landmarks are missing or obstructed by metal artefacts, it is challenging to accurately merge cone beam computed tomography (CBCT) and intraoral scanning (IOS) information, and the accuracy of the implant surgical guides would be compromised. This article describes a novel technical note using oral wound dressings and flowable resin as additional new radiopaque fiducial landmarks to design surgical guides for full-arch immediate implant placement. This technical note provided an accurate, convenient, and cost-effective option for the clinician.

Accuracy of robotic computer-assisted implant surgery for immediate implant placement: A retrospective case series study

OBJECTIVES

This study investigated the accuracy of robotic computer-assisted implant surgery (r-CAIS) for immediate implant placement.

METHODS

Twenty cases with 20 implant sites were selected based on predefined inclusion criteria. The preparation of the implant bed and implant placement followed the standardized dental implant robotic surgery protocol. Postoperative cone-beam computed tomography scans were conducted to assess possible discrepancies between actual and planned implant positions.

RESULTS

The r-CAIS technology for immediate implant placement exhibited a mean global coronal deviation of 0.71 ± 0.27 mm (95% CI: 0.58-0.83 mm), a mean global apical deviation of 0.69 ± 0.26 mm (95% CI: 0.56-0.81 mm), and an angular deviation of 1.27 ± 0.47° (95% CI: 1.05-1.49°). A substantial number of deviations were observed buccally at both coronal (90%) and apical (95%) levels, with a consistent tendency for buccal deviation.

CONCLUSIONS

The r-CAIS technology proved a promising approach for immediate implantation in the anterior region, with satisfactory clinical outcomes. However, an optimized surgical protocol for r-CAIS technology is required for particular implant sites like extraction sockets or bone defects.

Accuracy of a calibration method based on cone beam computed tomography and intraoral scanner data registration for robot-assisted implant placement: An in vitro study

STATEMENT OF PROBLEM

Robotic systems have shown promise for implant placement because of their accuracy in identifying surgical positions. However, research on the accuracy of patient calibration methods based on cone beam computed tomography (CBCT) and intraoral scanner (IOS) data registration is lacking.

PURPOSE

The purpose of this in vitro study was to develop a calibration method based on the registration of CBCT and IOS data of a robot-assisted system for implant placement, evaluate the accuracy of this calibration method, and explore the accuracy of robot-assisted surgery at different implant positions.

MATERIAL AND METHODS

Twenty standardized, polyurethane, partially edentulous maxillary typodonts were divided into 2 groups: one group used a calibration method based solely on CBCT data (CBCT group), and the other used a calibration method based on the registration of CBCT and IOS data (IOS group). Four implants were planned for each typodont in the right second premolar, left central incisor, left first premolar, and left second molar positions. The robot performed the osteotomies and implant placement step by step according to the preoperative plan. The operating software program automatically measured the deviation between the planned and actual implant position. Two-way analysis of variance (ANOVA) and the least significant difference (LSD) post hoc test (α=.05) were used to analyze differences between the test groups.

RESULTS

The angular deviation and 3-dimensional deviations at implant platform and apex between the 2 calibration methods did not significantly differ among the 4 implant positions (P>.05). The horizontal and depth deviations at the implant platform and apex levels between the 2 calibration methods did not significantly differ among the 4 implant positions (P>.05). In the anterior region (left central incisor), the CBCT group showed higher horizontal deviation at both the implant platform and apex compared with the IOS group (P<.05). Conversely, the IOS group had greater depth deviation at both the implant platform and apex than the CBCT group (P<.05). In the posterior region, with or without distal extension (right second premolar, left first premolar, and left second molar), no statistically significant differences were found between the 2 calibration methods (P>.05).

CONCLUSIONS

The calibration method that was based on the registration of CBCT and IOS data demonstrated high accuracy. No significant differences in the accuracy of the calibration methods for robot-assisted implant placement were found between the CBCT group and IOS group.

Accuracy of markerless registration methods of DICOM and STL files used for computerized surgical guides in mandibles with metal restorations: An in vitro study

STATEMENT OF PROBLEM

Digital imaging and communications in medicine (DICOM) files together with surface scans must be accurately registered in virtual implant planning software programs to match real-life dimensions and ensure correct plan transfer through computer-aided manufactured surgical guides.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of 3 different registration methods of DICOM data with and without metal restorations and a metal artifact reduction (MAR) tool for surface scans.

MATERIAL AND METHODS

Thirteen dentate mandibles were assigned to each group of this study (n=39). Baseplate wax was adapted to the bone surfaces of each mandible, and 5 radiopaque markers were attached. A desktop scanner was used to obtain control scans. The groups of metal-free mandibles (MFM) and mandibles with metal restorations (MRM) were scanned to obtain DICOM data without a MAR tool. Additional DICOM data for the MRM were obtained with the MAR tool (MRM-MAR). Point-based registration (PBR), best-fit registration (BFR), and automatic registration (AR) were used to align standard tessellation language (STL) and DICOM data, and 3 data sets were exported. Radiographic markers on each data set were compared with those on the control scan, and positional deviations were calculated and statistically evaluated with 1-way ANOVA followed by multiple pairwise comparisons, independent samples t test, and 2-way ANOVA (α=.05).

RESULTS

Within each group, PBR had the lowest deviation values with statistical significance in the MFM and the MRM-MAR groups (P<.001). AR showed failure in the MRM and the MRM-MAR groups. Statistically significant differences were found on comparing the average deviations among the 3 groups for PBR only (P<.001). No association was found between deviation values and the presence or absence of metal restoration, while a positive association was found with the type of registration method (P<.001).

CONCLUSIONS

PBR had the highest accuracy level compared with AR and BFR methods. An increase in the number of calculations resulted in more deviation values. The MAR tool had a positive effect on PBR in mandibles with metal restorations.

Validation of a novel AI-based automated multimodal image registration of CBCT and intraoral scan aiding presurgical implant planning

OBJECTIVES

The objective of this study is to assess accuracy, time-efficiency and consistency of a novel artificial intelligence (AI)-driven automated tool for cone-beam computed tomography (CBCT) and intraoral scan (IOS) registration compared with manual and semi-automated approaches.

MATERIALS AND METHODS

A dataset of 31 intraoral scans (IOSs) and CBCT scans was used to validate automated IOS-CBCT registration (AR) when compared with manual (MR) and semi-automated registration (SR). CBCT scans were conducted by placing cotton rolls between the cheeks and teeth to facilitate gingival delineation. The time taken to perform multimodal registration was recorded in seconds. A qualitative analysis was carried out to assess the correspondence between hard and soft tissue anatomy on IOS and CBCT. In addition, a quantitative analysis was conducted by measuring median surface deviation (MSD) and root mean square (RMS) differences between registered IOSs.

RESULTS

AR was the most time-efficient, taking 51.4 ± 17.2 s, compared with MR (840 ± 168.9 s) and SR approaches (274.7 ± 100.7 s). Both AR and SR resulted in significantly higher qualitative scores, favoring perfect IOS-CBCT registration, compared with MR (p = .001). Additionally, AR demonstrated significantly superior quantitative performance compared with SR, as indicated by low MSD (0.04 ± 0.07 mm) and RMS (0.19 ± 0.31 mm). In contrast, MR exhibited a significantly higher discrepancy compared with both AR (MSD = 0.13 ± 0.20 mm; RMS = 0.32 ± 0.14 mm) and SR (MSD = 0.11 ± 0.15 mm; RMS = 0.40 ± 0.30 mm).

CONCLUSIONS

The novel AI-driven method provided an accurate, time-efficient, and consistent multimodal IOS-CBCT registration, encompassing both soft and hard tissues. This approach stands as a valuable alternative to manual and semi-automated registration approaches in the presurgical implant planning workflow.

Validation of automated registration of intraoral scan onto Cone Beam Computed Tomography for an efficient digital dental workflow

OBJECTIVE

This study aimed to validate a newly developed automated method (Virtual Patient Creator, Relu, Leuven, Belgium) for multimodal registration of intraoral scan (IOS) and Cone Beam Computed Tomography (CBCT).

METHODS

Time point-matched IOS and CBCT scans of forty patients with variable dental statuses (natural dentition, partial edentulism, presence of orthodontic brackets) were selected. Three operators registered IOS and CBCT scans using three state-of-the-art softwares for orthodontics and orthognathic surgery (IPS Case Designer, Proplan CMF and Dolphin Imaging). Automated registration was compared to expert-performed semi-automated registration. Time consumption, accuracy, and consistency of the proposed method were benchmarked to semi-automated registration using root mean squared error calculations. The robustness of the automated registration was evaluated in relationship to the dental status of the patients in the dataset.

RESULTS

On average, automatic registration was 7.3 times faster than semi-automatic registration performed by an expert operator. Automatic registration yielded reliable results with low deviation errors compared to the differently skilled operators and semi-automated software. Automated registration surpassed human variability as expressed in intra- and inter-operator inconsistencies. Neither orthodontic brackets nor edentulism impacted registration accuracy.

CONCLUSIONS

The presented automated method for IOS and CBCT registration is faster, equally accurate, and more consistent than semi-automatic registration performed by an expert or an occasional operator. With similar results among cases with different dental statuses, the clinical feasibility of the method is ensured.

CLINICAL SIGNIFICANCE

A validated automated registration method provides accurate and fast multimodal image integration without incorporating operator bias at the very start of the digital workflows for dentistry, periodontics, orthodontics and orthognathic surgery.

Accuracy of manual and artificial intelligence-based superimposition of cone-beam computed tomography with digital scan data, utilizing an implant planning software: A randomized clinical study

OBJECTIVES

To investigate the accuracy of conventional and automatic artificial intelligence (AI)-based registration of cone-beam computed tomography (CBCT) with intraoral scans and to evaluate the impact of user's experience, restoration artifact, number of missing teeth, and free-ended edentulous area.

MATERIALS AND METHODS

Three initial registrations were performed for each of the 150 randomly selected patients, in an implant planning software: one from an experienced user, one from an inexperienced operator, and one from a randomly selected post-graduate student of implant dentistry. Six more registrations were performed for each dataset by the experienced clinician: implementing a manual or an automatic refinement, selecting 3 small or 3 large in-diameter surface areas and using multiple small or multiple large in-diameter surface areas. Finally, an automatic AI-driven registration was performed, using the AI tools that were integrated into the utilized implant planning software. The accuracy between each type of registration was measured using linear measurements between anatomical landmarks in metrology software.

RESULTS

Fully automatic-based AI registration was not significantly different from the conventional methods tested for patients without restorations. In the presence of multiple restoration artifacts, user's experience was important for an accurate registration. Registrations' accuracy was affected by the number of free-ended edentulous areas, but not by the absolute number of missing teeth (p < .0083).

CONCLUSIONS

In the absence of imaging artifacts, automated AI-based registration of CBCT data and model scan data can be as accurate as conventional superimposition methods. The number and size of selected superimposition areas should be individually chosen depending on each clinical situation.

A fully digital planning protocol for dynamic computer-assisted zygomatic implant surgery based on virtual surgery simulation: A dental technique

Dynamic navigation-guided zygomatic implant (ZI) surgery has been a preferred option for achieving optimal prosthetic-driven implant placement. However, during the actual surgical procedure, surgical execution may still be hindered by environmental factors such as mouth opening. A fully digital planning protocol is described that integrated the patient's maxillofacial soft tissue information and virtual surgical handpiece with the drills on the implant planning path to ensure the precise, time-saving, and smooth implementation of dynamic navigation-guided ZI surgery.

The effect on the performance of a dynamic navigation system of superimposing a standard tessellation language (STL) file obtained with an intraoral scan on a cone beam computer tomograph (CBCT). An experimental in vitro study

OBJECTIVES

To compare the accuracy and operative time of implant placement using a dynamic computer assisted implant surgery (dCAIS) system based on a cone beam computer tomography (CBCT) image, with and without superimposing a standard tessellation language (STL) file of an intraoral scan of the patient.

METHODS

Ten identical resin models simulating an upper maxilla with posterior edentulism were assigned to two groups. In the CBCT+STL group, a CBCT file and an intraoral STL file were superimposed and used for registration; in the CBCT group, registration was performed using CBCT images. Six implants were placed in each model using the Navident® dynamic navigation system. Anatomy registration was performed by tracing fiducial points on the CBCT or STL image, depending on the group. Preoperative and postoperative CBCT images were overlaid to assess implant placement accuracy.

RESULTS

Sixty implants were analyzed (30 implants in each group). 3D platform deviation was significantly lower (mean difference (MD): 0.17 mm; 95 % confidence interval (CI): 0.01 to 0.23; P = 0.039) in the CBCT+STL group (mean: 0.71 mm; standard deviation (SD): 0.29) than in the CBCT group (mean: 0.88 mm; SD: 0.39). The remaining accuracy outcome variables (angular deviation MD: -0.01; platform lateral deviation MD: 0.08 mm; apex global MD: 0.01 mm; apex depth MD: 0.33 mm) and surgery time (MD: 3.383 min.) were similar in both groups (p > 0.05).

CONCLUSIONS

The introduction of an intraoral scan (STL) seems to reduce deviations slightly in dental implant placement with dCAIS systems. However, the clinical repercussion of this improvement is questionable.

CLINICAL SIGNIFICANCE

Superimposing an intraoral scan on the CBCT image does not seem to increase the accuracy of dCAIS systems but can be useful when radiographic artifacts are present.

Accuracy of Implant Guided Surgery in Fully Edentulous Patients: Prediction vs. Actual Outcome-Systematic Review

Objectives: Examine deviations between the digitally planned and actual implant positions in clinical studies using static fully guided surgical guides. Identify potential associated factors and strategies to minimize their likelihood. Materials and Methods: This systematic review was conducted following the PRISMA checklist. The literature search was conducted in the PubMed® and Scopus® databases up to February 2024 following the PICOS search strategy. Clinical trials conducted between 2013 and 2024, evaluating the accuracy of static fully guided surgical guides placed in fully edentulous patients, were included. The studies had to assess at least two of the following parameters: angular deviation, cervical deviation, apical deviation, and depth deviation. Results: Out of the 298 articles initially searched, six randomized clinical trials and three clinical trials were included. All but one article used mucosa-supported guides; the remaining one used bone-supported guides. Apical deviations were more significant than cervical deviations, and implants tended to be placed too superficially. The greatest mean deviations were 2.01 ± 0.77 mm for cervical and 2.41 ± 1.45 mm for apical deviations, with the largest angular deviation recorded at 4.98 ± 2.16°. Conclusions: The accuracy of the surgical guide is influenced by various factors, including the technique of image acquisition and subsequent planning, guide support methods, and the adopted surgical protocol. Apical deviations are influenced by cervical and angular deviations. Additionally, deviations were more pronounced in the mandible. Further studies with similar methodologies are necessary for a more precise assessment of the different factors and for establishing safety margins.

Computer-assisted and robotic implant surgery: Assessing the outcome measures of accuracy and educational implications

OBJECTIVE

This scoping review aimed to (1) critically evaluate the outcomes measures used to assess the accuracy of implant placement with Computer Assisted Implant Surgery (CAIS) and (2) review the evidence supporting the efficient implementation of CAIS in training and education of clinicians.

METHODS

A scoping literature review was conducted aiming to identify (a) clinical trials assessing accuracy of implant placement with CAIS, and (b) clinical trials or simulation/cadaver studies where CAIS was utilised and assessed for the training/education of clinicians. Studies since 1995 were assessed for suitability and data related to the outcomes measures of accuracy and educational efficacy were extracted and synthesised.

RESULTS

Accuracy of CAIS has been mainly assessed through surrogate measures. Individual clinical trials have not shown any difference between static and dynamic CAIS, but recent meta-analyses suggest an advantage of dynamic CAIS in reducing angular deviation. The combination of static and dynamic CAIS might offer higher accuracy than each of the two used alone. Dynamic CAIS is suitable for novice surgeons and might even have added value as an education tool for implant surgery, although mastering the technique requires longer training than static.

CONCLUSION

Meta-analyses of large samples, new and diverse outcomes measures, as well as benchmarking of levels of accuracy with specific clinical outcomes will help to better understand the potential and limitations of CAIS. Dynamic CAIS is suitable for novice operators, but educational interventions distributed over longer periods of time will be required for mastery of the process.

The influence of metal artifact reduction on the trueness of registration of a cone-beam computed tomography scan with an intraoral scan in the presence of severe restoration artifact

PURPOSE

When planning guided implant surgery, highly radiopaque materials such as metals or zirconia produce streaking artifacts ('metal artifact') on cone-beam computed tomography scans, which can impair registration of the intraoral scan. This study aimed to determine the effect of metal artifact reduction on the trueness of registration in the presence of multiple full-coverage zirconia crowns.

MATERIALS AND METHODS

A 3D-printed maxillary study model was restored with 12 full-coverage zirconia crowns and scanned with an intraoral scanner. Cone-beam computed tomography scans of the study model were acquired, with and without activation of the metal artifact reduction algorithm. Registration of the optical scans was performed using initial point-based registration with surface-based refinement, and the deviation was measured at four pre-defined dental landmarks. Welch's t-test was used to compare the registration error for the metal artifact reduction group with the control group.

RESULTS

The average registration error was 0.519 mm (95% CI 0.507 to 0.531) with metal artifact reduction deactivated, compared to 0.478 mm (95% CI 0.460 to 0.496) without metal artifact reduction. Therefore, activation of the metal artifact reduction algorithm was associated with a 0.041 mm (95% CI 0.020 to 0.061, p < 0.001) increase in average registration error.

CONCLUSIONS

The use of the metal artifact reduction algorithm slightly reduced trueness in this in vitro study. Clinicians are advised not to rely on a metal artifact reduction (MAR) algorithm for registration of a cone-beam computed tomography scan with an intraoral scan when planning guided implant surgery in the presence of restoration artifacts.

The current role and future potential of digital diagnostic imaging in implant dentistry: A scoping review

OBJECTIVES

Diagnostic imaging is crucial for implant dentistry. This review provides an up-to-date perspective on the application of digital diagnostic imaging in implant dentistry.

METHODS

Electronic searches were conducted in PubMed focusing on the question 'when (and why) do we need diagnostic imaging in implant dentistry?' The search results were summarised to identify different applications of digital diagnostic imaging in implant dentistry.

RESULTS

The most used imaging modalities in implant dentistry include intraoral periapical radiographs, panoramic views and cone beam computed tomography (CBCT). These are dependent on acquisition standardisation to optimise image quality. Particularly for CBCT, other technical parameters (i.e., tube current, tube voltage, field-of-view, voxel size) are relevant minimising the occurrence of artefacts. There is a growing interest in digital workflows, integrating diagnostic imaging and automation. Artificial intelligence (AI) has been incorporated into these workflows and is expected to play a significant role in the future of implant dentistry. Preliminary evidence supports the use of ionising-radiation-free imaging modalities (e.g., MRI and ultrasound) that can add value in terms of soft tissue visualisation.

CONCLUSIONS

Digital diagnostic imaging is the sine qua non in implant dentistry. Image acquisition protocols must be tailored to the patient's needs and clinical indication, considering the trade-off between radiation exposure and needed information. growing evidence supporting the benefits of digital workflows, from planning to execution, and the future of implant dentistry will likely involve a synergy between human expertise and AI-driven intelligence. Transiting into ionising-radiation-free imaging modalities is feasible, but these must be further developed before clinical implementation.

Accuracy of computer-guided implant surgery in partially edentulous patients: a prospective observational study

PURPOSE

This study aims to evaluate the amount of distortion using computer-guided implant surgery with 3D printed surgical guides in limited edentulous spaces.

MATERIALS AND METHODS

25 bone level self-tapping implants (Straumann® BL and BLT) were randomly inserted in either distal or intercalary posterior mandibular edentulism using a fully digital protocol and 3D printed surgical guides. Amount of inaccuracy was evaluated after superimposing the 3 coordinates of virtually planned and final implant images, which were obtained using intra-oral scans and scan bodies. Four evaluation parameters were considered: origo-displacement, error depth, apical displacement and angle between the planned and the placed implant.

RESULTS

The average of distortion was 0.71 mm for the origo-displacement, 0.36 mm for the error depth, 0.52 mm for the horizontal displacement and 3.34º for the error angle.

CONCLUSION

The major reason of exclusion was CBCT artifacts. Results of this study were aligned with the results of previous studies concerning partially edentulous spaces. CAD/CAM manufacturing process did not result in significant distortion whilst the biggest part of distortions originated from the surgical process. The learning curve in computer-guided implant surgery presented an important source of inaccuracy.

Superimposing digital arch scans onto cone beam computed tomography scans with metallic artifacts by applying a radiopaque occlusal registration material: A chairside dental technique

Precise alignment between digital arch scans and cone beam computed tomography (CBCT) scans is a crucial step in computer-aided implant planning and placement. However, clinicians frequently encounter challenges during this process when imaging patients with existing metal restorations or orthodontic devices, as these can introduce metallic artifacts on CBCT scans that lead to alignment deviations. The presented technique describes a straightforward approach using a radiopaque occlusal registration material as a radiographic marker to facilitate the alignment between digital arch scans and CBCT scans with metallic artifacts. This technique simplifies the clinical workflow by eliminating the need for additional radiographic templates or specialized devices, offering a cost-effective option for clinicians.

Fully automatic integration of dental CBCT images and full-arch intraoral impressions with stitching error correction via individual tooth segmentation and identification

We present a fully automated method of integrating intraoral scan (IOS) and dental cone-beam computerized tomography (CBCT) images into one image by complementing each image's weaknesses. Dental CBCT alone may not be able to delineate precise details of the tooth surface due to limited image resolution and various CBCT artifacts, including metal-induced artifacts. IOS is very accurate for the scanning of narrow areas, but it produces cumulative stitching errors during full-arch scanning. The proposed method is intended not only to compensate the low-quality of CBCT-derived tooth surfaces with IOS, but also to correct the cumulative stitching errors of IOS across the entire dental arch. Moreover, the integration provides both gingival structure of IOS and tooth roots of CBCT in one image. The proposed fully automated method consists of four parts; (i) individual tooth segmentation and identification module for IOS data (TSIM-IOS); (ii) individual tooth segmentation and identification module for CBCT data (TSIM-CBCT); (iii) global-to-local tooth registration between IOS and CBCT; and (iv) stitching error correction for full-arch IOS. The experimental results show that the proposed method achieved landmark and surface distance errors of 112.4μm and 301.7μm, respectively.

Artificial intelligence serving pre-surgical digital implant planning: A scoping review

OBJECTIVES

To conduct a scoping review focusing on artificial intelligence (AI) applications in presurgical dental implant planning. Additionally, to assess the automation degree of clinically available pre-surgical implant planning software.

DATA AND SOURCES

A systematic electronic literature search was performed in five databases (PubMed, Embase, Web of Science, Cochrane Library, and Scopus), along with exploring gray literature web-based resources until November 2023. English-language studies on AI-driven tools for digital implant planning were included based on an independent evaluation by two reviewers. An assessment of automation steps in dental implant planning software available on the market up to November 2023 was also performed.

STUDY SELECTION AND RESULTS

From an initial 1,732 studies, 47 met eligibility criteria. Within this subset, 39 studies focused on AI networks for anatomical landmark-based segmentation, creating virtual patients. Eight studies were dedicated to AI networks for virtual implant placement. Additionally, a total of 12 commonly available implant planning software applications were identified and assessed for their level of automation in pre-surgical digital implant workflows. Notably, only six of these featured at least one fully automated step in the planning software, with none possessing a fully automated implant planning protocol.

CONCLUSIONS

AI plays a crucial role in achieving accurate, time-efficient, and consistent segmentation of anatomical landmarks, serving the process of virtual patient creation. Additionally, currently available systems for virtual implant placement demonstrate different degrees of automation. It is important to highlight that, as of now, full automation of this process has not been documented nor scientifically validated.

CLINICAL SIGNIFICANCE

Scientific and clinical validation of AI applications for presurgical dental implant planning is currently scarce. The present review allows the clinician to identify AI-based automation in presurgical dental implant planning and assess the potential underlying scientific validation.

Magnetic resonance imaging in dental implant surgery: a systematic review

PURPOSE

To comprehensively assess the existing literature regarding the rapidly evolving in vivo application of magnetic resonance imaging (MRI) for potential applications, benefits, and challenges in dental implant surgery.

METHODS

Electronic and manual searches were conducted in PubMed MEDLINE, EMBASE, Biosis, and Cochrane databases by two reviewers following the PICOS search strategy. This involved using medical subject headings (MeSH) terms, keywords, and their combinations.

RESULTS

Sixteen studies were included in this systematic review. Of the 16, nine studies focused on preoperative planning and follow-up phases, four evaluated image-guided implant surgery, while three examined artifact reduction techniques. The current literature highlights several MRI protocols that have recently investigated and evaluated the in vivo feasibility and accuracy, focusing on its potential to provide surgically relevant quantitative and qualitative parameters in the assessment of osseointegration, peri-implant soft tissues, surrounding anatomical structures, reduction of artifacts caused by dental implants, and geometric accuracy relevant to implant placement. Black Bone and MSVAT-SPACE MRI, acquired within a short time, demonstrate improved hard and soft tissue resolution and offer high sensitivity in detecting pathological changes, making them a valuable alternative in targeted cases where CBCT is insufficient. Given the data heterogeneity, a meta-analysis was not possible.

CONCLUSIONS

The results of this systematic review highlight the potential of dental MRI, within its indications and limitations, to provide perioperative surgically relevant parameters for accurate placement of dental implants.

Digital registration versus cone-beam computed tomography for evaluating implant position: a prospective cohort study

BACKGROUND

Postoperative cone-beam computed tomography (CBCT) examination is considered a reliable method for clinicians to assess the positions of implants. Nevertheless, CBCT has drawbacks involving radiation exposure and high costs. Moreover, the image quality can be affected by artifacts. Recently, some literature has mentioned a digital registration method (DRM) as an alternative to CBCT for evaluating implant positions. The aim of this clinical study was to verify the accuracy of the DRM compared to CBCT scans in postoperative implant positioning.

MATERIALS AND METHODS

A total of 36 patients who received anterior maxillary implants were included in this clinical study, involving a total of 48 implants. The study included 24 patients in the single implant group and 12 patients in the dual implant group. The postoperative three-dimensional (3D) positions of implants were obtained using both CBCT and DRM. The DRM included three main steps. Firstly, the postoperative 3D data of the dentition and intraoral scan body (ISB) was obtained through the intraoral scan (IOS). Secondly, a virtual model named registration unit which comprised an implant replica and a matching ISB was created with the help of a lab scanner and reverse engineering software. Thirdly, by superimposing the registration unit and IOS data, the postoperative position of the implant was determined. The accuracy of DRM was evaluated by calculating the Root Mean Square (RMS) values after superimposing the implant positions obtained from DRM with those from postoperative CBCT. The accuracy of DRM was compared between the single implant group and the dual implant group using independent sample t-tests. The superimposition deviations of CBCT and IOS were also evaluated.

RESULTS

The overall mean RMS was 0.29 ± 0.05 mm. The mean RMS was 0.30 ± 0.03 mm in the single implant group and 0.29 ± 0.06 mm in the dual implant group, with no significant difference (p = 0.27). The overall registration accuracy of the IOS and CBCT data ranged from 0.14 ± 0.05 mm to 0.21 ± 0.08 mm.

CONCLUSION

In comparison with the 3D implant positions obtained by CBCT, the implant positions located by the DRM showed clinically acceptable deviation ranges. This method can be used in single and dual implant treatments to assess the implant positions.

Facially driven guided crown lengthening using a complete digital workflow: A dental technique

A facially driven digital guided crown lengthening method using the virtual smile design approach supplemented with a static 3-dimensional face scan that demonstrates the digital data of extraoral soft tissue is presented. The technique enables the practitioner to virtually design the new smile and surgically plan the crown lengthening procedure.

Considerations for predictable outcomes in static computer- aided implant surgery in the esthetic zone

OBJECTIVE

To provide technical and clinical recommendations for implementing a digital workflow in Static Computer-Aided Implant Surgery in the anterior maxilla.

CLINICAL CONSIDERATIONS

An optimal 3D implant position is crucial for achieving satisfying results in implant rehabilitation in the esthetic area. Due to its complexity, implant placement in the esthetic zone should be executed with precision and predictability. Static Computer-Aided Implant Surgery requires thorough planning and detailed attention to every step of the digital workflow protocol.

CONCLUSIONS

Implant positioning in the esthetic zone using Static Computer-Aided Implant Surgery is a technique-sensitive procedure that requires precise execution of each step. This approach ensures accurate prosthetically driven 3D implant placement and prevents potential errors that could lead to inaccurate positioning.

CLINICAL SIGNIFICANCE

The proper implementation of Static Computer-Aided Implant Surgery may increase the level of agreement between the planned and definitive implant 3D positions in the esthetic zone, thus enhancing the esthetic outcomes of implant rehabilitation.

Recommendations for successful virtual patient-assisted esthetic implant rehabilitation: A guide for optimal function and clinical efficiency

OBJECTIVE

Complete arch implant rehabilitation necessitates meticulous treatment planning and high-level collaboration between surgical and prosthetic dental teams. Emerging virtual technologies hold considerable promise in streamlining this process. The aim of this article is to extend recommendations to clinicians venturing into the virtual patient-assisted esthetic implant rehabilitation workflow.

OVERVIEW

This article summarizes recommendations for virtual patient-assisted esthetic implant rehabilitation in the following five aspects: three-dimensional data handling and superimposition, occlusion and virtual articulator integration in creating virtual patients, streamlined face- and prosthetic-driven surgical planning, reuse of presurgical data ("Copy & Paste"), and final impression for passive fitting of final restoration. To illustrate these principles, a case with complete-mouth implant rehabilitation completed within six visits using this virtual patient workflow is presented.

CONCLUSION

The virtual patient workflow serves as an invaluable tool to perform treatment planning, enhance efficiency, and ensure predictable outcomes in esthetic complete arch implant rehabilitation.

CLINICAL SIGNIFICANCE

Virtual workflows are increasingly prevalent in esthetic implant rehabilitation. Nevertheless, these workflows necessitate a distinct set of knowledge and tools divergent from conventional dentistry practices. This article offers guidelines and recommendations for dental clinicians who are new to this field.

Accuracy of autonomous robotic surgery for dental implant placement in fully edentulous patients: A retrospective case series study

OBJECTIVES

This study evaluated the accuracy of dental implant placement using the robotic computer-assisted implant surgery (r-CAIS) technology in fully edentulous patients.

MATERIALS AND METHODS

Fully edentulous and terminal dentition patients were enrolled for r-CAIS technology. Based on the cone-beam computed tomography (CBCT) examination, a customized positioning marker and a preoperative surgical plan were created before surgery. During the implant surgery, the implant osteotomy and placement were automatically performed using an autonomous robotic surgery system under the surgeon's supervision. A postoperative CBCT scan was used to determine the discrepancies between the planned and placed implants.

RESULTS

Ten patients with 59 implants underwent autonomous robotic surgery. No adverse surgical events occurred. The deviations of global coronal, global apical, and angular were 0.67 ± 0.37 mm (95% CI: 0.58-0.77 mm), 0.69 ± 0.37 mm (95% CI: 0.59-0.78 mm), and 1.27° ± 0.59° (95% CI: 1.42°-1.11°), respectively.

CONCLUSIONS

The autonomous r-CAIS technology proved an accurate surgical approach for implant placement in fully edentulous patients due to the control of the angular deviation. Autonomous robotic surgery seems promising as an accurate technology for treating fully edentulous patients. However, further trials are required to provide more hard clinical evidence.

Novel Procedure for Automatic Registration between Cone-Beam Computed Tomography and Intraoral Scan Data Supported with 3D Segmentation

In contemporary practice, intraoral scans and cone-beam computed tomography (CBCT) are widely adopted techniques for tooth localization and the acquisition of comprehensive three-dimensional models. Despite their utility, each dataset presents inherent merits and limitations, prompting the pursuit of an amalgamated solution for optimization. Thus, this research introduces a novel 3D registration approach aimed at harmonizing these distinct datasets to offer a holistic perspective. In the pre-processing phase, a retrained Mask-RCNN is deployed on both sagittal and panoramic projections to partition upper and lower teeth from the encompassing CBCT raw data. Simultaneously, a chromatic classification model is proposed for segregating gingival tissue from tooth structures in intraoral scan data. Subsequently, the segregated datasets are aligned based on dental crowns, employing the robust RANSAC and ICP algorithms. To assess the proposed methodology's efficacy, the Euclidean distance between corresponding points is statistically evaluated. Additionally, dental experts, including two orthodontists and an experienced general dentist, evaluate the clinical potential by measuring distances between landmarks on tooth surfaces. The computed error in corresponding point distances between intraoral scan data and CBCT data in the automatically registered datasets utilizing the proposed technique is quantified at 0.234 ± 0.019 mm, which is significantly below the 0.3 mm CBCT voxel size. Moreover, the average measurement discrepancy among expert-identified landmarks ranges from 0.368 to 1.079 mm, underscoring the promise of the proposed method.

Integrating a mouth opening assessment of virtual patients to prevent intraoperative challenges during treatment

Template-guided implant surgery in the posterior region or zygomatic implant surgery using dynamic navigation systems is often hindered if a patient has limited mouth opening. To overcome the problem, the authors have proposed a novel digital protocol that integrates the use of a facial scan for the assessment of the maximal mouth opening of a virtual patient to assist in preoperative planning, thereby minimizing the likelihood of intraoperative obstruction of the surgical site. The proposed method is cost effective and can be easily used in clinical practice.

Accuracy of a novel modified single computed tomography scanning method for assisting dental implant placement: a retrospective observational study

PURPOSE

The aim of this study is to compare dental implant placement accuracy of three surgical guide fabrication methods: single (SCT) and double computed tomography (DCT), and a newly developed modified SCT (MSCT) scan method.

METHODS

A total of 183 cases (183 surgical guides, and 485 implants) of static-guide-assisted implant placement surgery using the SCT, DCT, or MSCT methods in a dental clinic were included in the study. Three-dimensional (3D) deviations (mm) at the entry and tip of the implant body between preoperative simulation and actual placement were measured as surrogate endpoints of implant placement accuracy. The following survey details were collected from medical records and CT data: sex, age at implant placement surgery, surgical guide fabrication method, number of remaining teeth, implant length, implant location, alveolar bone quality, and bone surface inclination at implant placement site in preoperative simulation, etc. Risk factors for reducing implant placement accuracy were investigated using generalized estimating equations.

RESULTS

The SCT and DCT methods (odds ratios [ORs] vs. MSCT method: 1.438, 1.178, respectively), posterior location (OR: 1.114), bone surface buccolingual inclination (OR: 0.997), and age at implant placement surgery (OR: 0.995) were significant risk factors for larger 3D deviation at the entry; the SCT (OR: 1.361) and DCT methods (OR: 1.418), posterior location (OR: 1.190), implant length (OR: 1.051), and age at implant placement surgery (OR: 0.995) were significant risk factors for larger 3D deviation at the tip of the implant body.

CONCLUSIONS

Implant placement accuracy was better using the MSCT method compared to the SCT and DCT methods.

Quantitative analysis of zirconia and titanium implant artefacts in three-dimensional virtual models of multi-slice CT and cone beam CT: does scan protocol matter?

OBJECTIVES

Artefacts from dental implants in three-dimensional (3D) imaging may lead to incorrect representation of anatomical dimensions and impede virtual planning in navigated implantology. The aim of this study was quantitative assessment of artefacts in 3D STL models from cone beam CT (CBCT) and multislice CT (MSCT) using different scanning protocols and titanium-zirconium (Ti-Zr) and zirconium (ZrO2) implant materials.

METHODS

Three ZrO2 and three Ti-Zr implants were respectively placed in the mandibles of two fresh human specimens. Before (baseline) and after implant placement, 3D digital imaging scans were performed (10 repetitions per timepoint: voxel size 0.2 mm³ and 0.3 mm³ for CBCT; 80 and 140 kV in MSCT). DICOM data were converted into 3D STL models and evaluated in computer-aided design software. After precise merging of the baseline and post-op models, the surface deviation was calculated, representing the extent of artefacts in the 3D models.

RESULTS

Compared with baseline, ZrO2 emitted 36.5-37.3% (±0.6-0.8) artefacts in the CBCT and 39.2-50.2% (±0.5-1.2) in the MSCT models. Ti-Zr implants produced 4.1-7.1% (±0.3-3.0) artefacts in CBCT and 5.4-15.7% (±0.5-1.3) in MSCT. Significantly more artefacts were found in the MSCT vs CBCT models for both implant materials (p < 0.05). Significantly fewer artefacts were visible in the 3D models from scans with higher kilovolts in MSCT and smaller voxel size in CBCT.

CONCLUSIONS

Among the four applied protocols, the lowest artefact proportion of ZrO2 and Ti-Zr implants in STL models was observed with CBCT and the 0.3 mm³ voxel size.

The in-vitro accuracy of fiducial marker-based versus markerless registration of an intraoral scan with a cone-beam computed tomography scan in the presence of restoration artifact

OBJECTIVES

To determine the effect of restoration artifact ('metal artifact') on registration accuracy of an intraoral scan and cone-beam computed tomography (CBCT) scan, comparing fiducial marker-based registration with markerless registration.

MATERIALS AND METHODS

A maxillary model was fitted with multiple configurations of zirconia crowns to simulate various states of oral rehabilitation. Intraoral scans and CBCT scans (half and full rotation) were acquired. Registration was performed using markerless (point-based registration with surface-based refinement) and fiducial marker-based registration. Each experimental condition was repeated 10 times (n = 320). The absolute deviation was measured at the canines and first molars, and the average and maximum values were analysed using multiple linear regression.

RESULTS

R2 was 0.874 for average error and 0.858 for maximum error. For markerless registration, there were 0.041 mm (p < .001) and 0.045 mm (p < .001) increases in average and maximum error per crown, respectively. For fiducial marker-based registration, the effect of additional crowns was not statistically significant for average (p = .067) or maximum (p = .438) error. For a full arch of crowns, the regression model predicted average and maximum errors of 0.581 and 0.697 mm for the markerless technique, and 0.185 and 0.210 mm for the fiducial marker-based technique. Overall, the fiducial marker-based technique was more accurate for four or more crowns. The half rotation scan increased average error by 0.021 mm (p = .001) and maximum error by 0.029 mm (p < .001).

CONCLUSIONS

Under the present study's experimental conditions, the fiducial marker-based technique should be considered if four or more full-coverage highly radiopaque restorations are present.

Accuracy of a Novel Semi-Autonomous Robotic-Assisted Surgery System for Single Implant Placement: a Case Series

OBJECTIVE

This study aimed to evaluate the accuracy of dental implant placement at single-tooth sites using a novel semi-autonomous robotic-assisted surgery system (sa-RASS).

METHODS

Patients with single missing teeth were included. Cone-beam computed tomography (CBCT) was performed prior to surgery using a U-shaped silicone tube to develop a virtual implant placement and drilling plan. The sa-RASS was used for implant osteotomy and placement in conjunction with a surgeon. Cone-beam computed tomography data were utilised to evaluate deviations between planned and placed implants using a three-dimensional Slicer software. Data were analysed using the t-test and analysis of variance. Statistical significance was considered at P<0.05.

RESULTS

Nineteen implants were placed using the sa-RASS. No adverse events or complications were observed during the surgery. Mean ± standard deviations between planned and postoperative implant positions were 0.90 ± 0.41 mm at the platform, 1.04 ± 0.47 mm at the apex, and 3.37 ± 1.51° for angulation. In a lateral direction, deviations were 0.72 ± 0.38 mm and 0.88 ± 0.47 mm at the platform and apex, respectively. Deviations in depth were all <1mm at both the platform (0.46 ± 0.33 mm) and apex (0.45 ± 0.32 mm). The apex deviation was greater than that at the platform (p = 0.036 < 0.05), mainly in the lateral distance (p = 0.037 < 0.05).

CONCLUSIONS

The current study illustrate that this robotic implant system is sufficiently accurate for single-tooth implant placement.

CLINICAL SIGNIFICANCE

This study provides significant evidence to support the use of sa-RASS as a potential alternative to static guided surgery and dynamic navigation, in dental implant surgery.

A systematic review of the accuracy of digital surgical guides for dental implantation

PURPOSE

This review aimed to reveal the influence of implant guides on surgical accuracy with regard to supporting types, manufacturing methods and design (including fixation screws and sleeves).

METHODS

A literature search related to accuracy of surgical guides for dental implantation was performed in Web of Science and PubMed. Studies with in vivo or in vitro deviation data published in recent 5 years (2018-2022) were included and assessed by Newcastle-Ottawa Scale with regard to risk of bias and reliability degree of clinical studies. Accuracy-related deviation data were summarized as forest plots and normal distributions.

RESULTS

Forty-one articles were included with high degree of credibility. Data showed that implant surgery accuracy can be achieved with mean distance deviation < 2 mm (most < 1 mm) and angular deviation < 8° (most < 5°).

CONCLUSIONS

Bilateral tooth-supported guides exhibited highest in vitro accuracy and similar in vivo accuracy to unilateral tooth-supported guides; mucosa-supported guides exhibit lowest in vivo accuracy, while its in vitro data showed low credibility due to mechanical complexity of living mucosa tissue. Milling exhibited higher in vivo accuracy of guides than 3d-printing, though further data support was needed. Design of fixation screws and sleeves of implant guides affected the surgical accuracy and might remain a research focus in near future. However, lack of universal evaluation standards for implantation accuracy remained a major problem in this field. The influence of implant guides on surgical accuracy revealed in this review might shed light on future development of dental implantology.

An additively manufactured, magnetically retained, and stackable implant surgical guide: A dental technique

The digital workflow for designing and fabricating a magnetically retained and stackable additively manufactured implant surgical guide is described. The technique should improve the stability of the stackable surgical guide and the accuracy of implant placement.

Does implant drill design influence the accuracy of dental implant placement using static computer-assisted implant surgery? An in vitro study

BACKGROUND

The purpose of this in vitro study was to compare the accuracy of implant placement in model surgeries according to the design of the drills (straight drills or step drills) used to finalize the implant bed during pilot-guided static computer-assisted implant surgery (sCAIS).

METHODS

Model surgeries were carried out on resin models randomly assigned to three study groups. Virtual planning software (coDiagnostiX 10.6, Dental Wings, Montreal, Canada) was used to plan the implant positions. In Groups 1 and 2, pilot-guided sCAIS was performed. Straight drills were used in Group 1, and step drills were used in Group 2 to finalize the implant beds. In Group 3, fully guided sCAIS was performed using a universal fully guided kit (RealGUIDE Full Surgical Kit 3DIEMME, RealGUIDE, Cantù, Como, Italy). A total of 90 dental implants (Callus Pro, Callus Implant Solutions GmbH, Nuremberg, Germany) were placed (six implants per model, five models per study group). The primary outcome variables (angular deviation, coronal global deviation, and apical global deviation) were calculated for all implants based on the comparison of the preoperative surgical plan with the postoperative scans.

RESULTS

Group 2 (coronal global deviation, 0.78 ± 0.29 mm; apical global deviation, 1.02 ± 0.56 mm) showed significantly lower values of both global deviation variables than Group 1 (coronal global deviation, 0.95 ± 0.20 mm; apical global deviation, 1.42 ± 0.49 mm). However, there was no significant difference in angular deviation between Groups 1 and 2 (7.56 ± 2.92° and 6.44 ± 2.84°). Group 3 produced significantly lower values of all three primary outcome variables (angular deviation, 2.36 ± 0.90°; coronal global deviation, 0.59 ± 0.28 mm; apical global deviation, 0.90 ± 0.29 mm) than Group 1 and significantly lower angular deviation and coronal global deviation values than Group 2.

CONCLUSIONS

The design of the drills used to finalize implant osteotomies during pilot-guided sCAIS influences dental implant placement accuracy. Using step drills instead of straight drills for final osteotomies decreases deviation from the surgical plan. The fully guided approach performed better than the pilot-guided sCAIS.

Accuracy of CAD-CAM surgically guided tooth autotransplantation using guided templates and custom-designed osteotomes in human cadaver mandibles

INTRODUCTION

A major challenge in dentistry is the replacement of teeth lost prematurely due to trauma, caries, or malformations, especially in growing patients. The aim of this study was to assess the accuracy of CAD-CAM surgically guided tooth autotransplantation in cryopreserved cadaver mandibles using guided templates and custom-designed osteotomes.

METHODS

Cryopreserved human cadaver heads were digitized and scanned using an intraoral optical scanner and a large-volume cone beam computed tomography (CBCT) device. First, virtual surgical planning was performed to create a 3D tooth replica, two surgical guides, and a custom-made osteotome for each single-rooted tooth autotransplantation procedure/case. Surgical sockets were created in the selected mandibles using guided tooling consisting of an initial guided osteotomy with implant burs and a final guided osteotomy using custom osteotomes. After tooth autotransplantation, second large-volume CBCT images of the five cadaver mandibles were obtained. The discrepancy in mm within the 3D space (apical and mesiodistal deviations) between the final position of the autotransplanted teeth and their digitally planned 3D initial position was calculated and analyzed statistically (P< .05).

RESULTS

All donor teeth were placed without incident within their newly created sockets in the real mandibles. The mean difference between the digitally planned root apex position and the final tooth position was 2.46±1.25mm. The mesiodistal deviation of the autotransplanted teeth was 1.63±0.96mm.

CONCLUSIONS

The autotransplantation of single-rooted teeth with custom-designed and 3D-printed surgical tooling provided promising results. The technique was able to create surgically prepared sockets that could accommodate transplanted teeth in mandibles.

Automatic registration of dental CT and 3D scanned model using deep split jaw and surface curvature

BACKGROUND AND OBJECTIVES

In the medical field, various image registration applications have been studied. In dentistry, the registration of computed tomography (CT) volume data and 3D optically scanned models is essential for various clinical applications, including orthognathic surgery, implant surgical planning, and augmented reality. Our purpose was to present a fully automatic registration method of dental CT data and 3D scanned models.

METHODS

We use a 2D convolutional neural network to regress a curve splitting the maxilla (i.e., upper jaw) and mandible (i.e., lower jaw) and the points specifying the front and back ends of the crown from the CT data. Using this regressed information, we extract the point cloud and vertices corresponding to the tooth crown from the CT and scanned data, respectively. We introduce a novel metric, called curvature variance of neighbor (CVN), to discriminate between highly fluctuating and smoothly varying regions of the tooth crown. The registration based on CVN enables more accurate fine registration while reducing the effects of metal artifacts. Moreover, the proposed method does not require any preprocessing such as extracting the iso-surface for the tooth crown from the CT data, thereby significantly reducing the computation time.

RESULTS

We evaluated the proposed method with the comparison to several promising registration techniques. Our experimental results using three datasets demonstrated that the proposed method exhibited higher registration accuracy (i.e., 2.85, 1.92, and 7.73 times smaller distance errors for individual datasets) and smaller computation time (i.e., 4.12 times faster registration) than one of the state-of-the-art methods. Moreover, the proposed method worked considerably well for partially scanned data, whereas other methods suffered from the unbalancing of information between the CT and scanned data.

CONCLUSIONS

The proposed method was able to perform fully automatic and highly accurate registration of dental CT data and 3D scanned models, even with severe metal artifacts. In addition, it could achieve fast registration because it did not require any preprocessing for iso-surface reconstruction from the CT data.

Accuracy of autonomous robotic surgery for single-tooth implant placement: A case series

OBJECTIVES

This study aimed to investigate the accuracy of the autonomous robotic computer-assisted implant surgery (r-CAIS) for single-tooth implant placement.

METHODS

Patients with a single missing tooth were enrolled for the autonomous robotic implant surgery. The patients underwent a cone-beam computed tomography (CBCT) scan with a positioning marker. Virtual preoperative implant placement and a drilling plan were created before surgery. The robotic system automatically performed the implant osteotomy and placement intraoperatively under the surgeon's supervision. A postoperative CBCT scan was performed to evaluate the deviations between the planned and placed implants.

RESULTS

Ten patients with single dental implant placement were enrolled. No adverse surgical events and postoperative complications (i.e., infection and early implant failure) were reported. The autonomous robotic implant surgery exhibited a mean overall coronal deviation of 0.74 mm (95% CI: 0.53 to 0.94 mm), a mean overall apical deviation of 0.73 mm (95% CI: 0.53 to 0.93 mm), and an angular deviation of 1.11° (95% CI: 0.78 to 1.44°), respectively.

CONCLUSIONS

The high accuracy of autonomous r-CAIS technology in single-tooth implant placement was attributed to the control of the angular deviation and axial errors.

CLINICAL SIGNIFICANCE

The main findings of this study provide significant evidence to support the autonomous robotic implant surgery system as a potential alternative in dental implant surgery.

Dental MRI-only a future vision or standard of care? A literature review on current indications and applications of MRI in dentistry

MRI is increasingly used as a diagnostic tool for visualising the dentoalveolar complex. A comprehensive review of the current indications and applications of MRI in the dental specialities of orthodontics (I), endodontics (II), prosthodontics (III), periodontics (IV), and oral surgery (V), pediatric dentistry (VI), operative dentistry is still missing and is therefore provided by the present work.The current literature on dental MRI shows that it is used for cephalometry in orthodontics and dentofacial orthopaedics, detection of dental pulp inflammation, characterisation of periapical and marginal periodontal pathologies of teeth, caries detection, and identification of the inferior alveolar nerve, impacted teeth and dentofacial anatomy for dental implant planning, respectively. Specific protocols regarding the miniature anatomy of the dentofacial complex, the presence of hard tissues, and foreign body restorations are used along with dedicated coils for the improved image quality of the facial skull.Dental MRI poses a clinically useful radiation-free imaging tool for visualising the dentoalveolar complex across dental specialities when respecting the indications and limitations.

Influence of planning software and surgical template design on the accuracy of static computer assisted implant surgery performed using surgical guides fabricated with material extrusion technology: An in vitro study

OBJECTIVES

This in vitro study aimed to assess the influence of the planning software and design of the surgical template on both trueness and precision of static computer assisted implant surgery (sCAIS) performed using surgical guides fabricated using material extrusion (ME).

METHODS

Three-dimensional radiographic and surface scans of a typodont were aligned using two planning software (coDiagnostiX, CDX; ImplantStudio, IST) to virtually position the two adjacent oral implants. Thereafter, surgical guides were created with either an original (O) or modified (M) design with reduced occlusal support and were steam sterilized. Forty surgical guides were used to instal 80 implants equally distributed among four groups: CDX-O, CDX-M, IST-O, and IST-M. Thereafter, the scan bodies were adapted to the implants and digitised. Finally, inspection software was used to assess discrepancies between the planned and final positions at the implant shoulder and main axis level. Multilevel mixed-effects generalised linear models were used for statistical analyses (p = 0.05).

RESULTS

In terms of trueness, the largest average vertical deviations (0.29 ± 0.07 mm) could be assessed for CDX-M. Overall, vertical errors were significantly dependent on the design (O < M; p ≤ 0.001). Furthermore, in horizontal direction, the largest mean discrepancy was 0.32 ± 0.09 mm (IST-O) and 0.31 ± 0.13 mm (CDX-M). CDX-O was superior compared to IST-O (p = 0.003) regarding horizontal trueness. The average deviations regarding the main implant axis ranged between 1.36 ± 0.41 ° (CDX-O) and 2.63 ± 0.87 ° (CDX-M). In terms of precision, mean standard deviation intervals of ≤ 0.12 mm (IST-O and -M) and ≤ 1.09 ° (CDX-M) were calculated.

CONCLUSIONS

Implant installation with clinically acceptable deviations is possible with ME surgical guides. Both evaluated variables affected trueness and precision with negligible differences.

CLINICAL SIGNIFICANCE

The planning system and design influenced the accuracy of implant installation using ME-based surgical guides. Nevertheless, discrepancies were ≤ 0.32 mm and ≤ 2.63 °, which may be considered within the range of clinical acceptance. ME should be further investigated as an alternative to the more expensive and time-consuming 3D printing technologies.