International Journal of Computerized Dentistry, 01/2023

Aim: The aim of the present ex vivo study was to examine the accuracy of augmented reality-assisted apicoectomies (AR-A) versus template-guided apicoectomies (TG-A). Materials and methods: In total, 40 apicoectomies were performed in 10 cadaver pig mandibles. Every pig mandible underwent two AR-A and two TG-A in molar and premolar teeth. A crossed experimental design was applied. AR-A was performed using Microsoft HoloLens 2, and TG-A using SMOP software. Postoperative CBCT scans were superimposed with the presurgical planning data. The deviation between the virtually planned apicoectomy and the surgically performed apicoectomy was measured. The primary (angular deviation [degrees]) and secondary (depth deviation [mm]) outcome parameters were measured. Results: Overall, 36 out of 40 apicoectomies could be included in the study. Regarding the primary outcome parameter (angular deviation), there was no significant difference between AR-A and TG-A. The mean values were 5.33 degrees (± 2.96 degrees) in the AR-A group, and 5.23 degrees (± 2.48 degrees) in the TG-A group. The secondary outcome parameter (depth deviation) showed no significant difference between the AR-A group of 0.27 mm (± 2.32 mm) and the TG-A group of 0.90 mm (± 1.84 mm). In this crossed experimental design, both techniques overshot the target depth in posterior sites, as opposed to not reaching the target depth in anterior sites (P < 0.001). Conclusion: Augmented reality (AR) technology has the potential to be introduced into apicoectomy surgery in case further development is implemented. Keywords: augmented reality (AR), augmented reality in dentistry, augmented reality in oral surgery, AR-assisted apicoectomy, template-guided apicoectomy, ex vivo study

Aim: To evaluate the trueness of seven different intraoral scanners (IOSs) in making a complete-arch digital scan with and without splinting the scan bodies. Materials and methods: A polyurethane cast of an edentulous mandible with four dental implant analogs was prepared. A reference scan was made using a laboratory scanner. The reference model was scanned with each of the seven investigated IOSs (control groups, n = 10 per scanner), and scanned again after splinting the scan bodies (study groups, n = 10 per scanner). Each scan was exported as a standard tessellation language (STL) file and transferred to a comprehensive metrology software program (Geomagic Control X). In order to measure the trueness, four points (A, B, C, and D) were determined on the scan bodies, and the distance between point A and the other points (DAB, DAC, and DAD) was measured. The measurements were tested for normality using the Kolmogorov-Smirnov test and probability plots. Trueness was compared using three-way analysis of variance (ANOVA), and pairwise comparisons were performed using the post hoc Tukey and paired sample t tests. Statistical analyses were two-sided, and the significance level was set at 5%. Results: Splinting the scan bodies improved the trueness values of the digital scans, while increasing the interimplant distance decreased them. A significant association was found between the trueness values and all three tested variables, including splinting the scan bodies, type of IOS, and interimplant distance (P < 0.001). Conclusion: Based on the present findings, splinting the scan bodies can improve the trueness of complete-arch digital implant scans due to the improvement in morphologic landmarks by the stitching process, regardless of the type of IOS or the interimplant distance. (Int J Comput Dent 2023;26(1): 19–0; doi: 10.3290/j.ijcd.b2599297) Keywords: dental implant, digital scan, intraoral scanner, scan body, splinting, trueness

Aim: The present study aimed to investigate the effect of pulp chamber depth on the failure load and mode of failure of CAD/CAM endocrowns. Materials and methods: Thirty mandibular molars were sectioned above the cementoenamel junction (CEJ), followed by root canal treatment. Teeth were sectioned at a level of 1.5 mm above the CEJ, arranged from the lowest to the highest depths, and divided into three groups (n = 10): group SE: Shallow pulp chamber (1.42 to 2.17 mm); group IE: Intermediate pulp chamber (2.25 to 3.17 mm); group DE: Deep pulp chamber (3.33 to 5.17 mm). CAD/CAM endocrowns were fabricated by milling lithium disilicate ceramic blocks and were cemented using resin cement. Teeth were embedded in acrylic resin at 2 mm below the CEJ, and a compressive load was applied to create a 45-degree angled functional loading simulation until the occurrence of failure. Results: The mean failure loads were highest in group DE (1893.75 ± 496.08 N) compared with groups IE (1103.71 ± 254.59 N) and SE (1084.63 ± 240.92 N), with statistically significant differences between group DE and both groups IE and SE (P < 0.001). Pearson correlation coefficient (PCC) revealed a strong positive correlation between the pulp chamber depth and failure load of the endocrowns. The failure mode for all samples was catastrophic failure. Conclusion: The pulp chamber depth affected the failure load of the teeth restored with endocrowns. The failure loads were higher in teeth with a greater pulp chamber depth. (Int J Comput Dent 2023;26(1): 31–0; doi: 10.3290/j.ijcd.b3818295) Keywords: endocrowns, failure load, failure mode, pulp chamber depth, restoration of endodontically treated teeth

Aim: The present study aimed to evaluate the marginal and internal fit of lithium disilicate crowns at various locations. Materials and methods: A typodont maxillary left first molar was prepared for a lithium disilicate crown, scanned, and a master die fabricated. Three groups were created according to fabrication method (n = 10): conventional impression and press method (group C); scanning of definitive cast and milling method (group D); and intraoral scanning and milling method (group I). Assessment was performed using the triple-scan protocol. At the buccopalatal and mesiodistal sections, the absolute marginal discrepancy (AMD), marginal gap (MG), axial internal gap (AI), and line angle internal gap (LI) were measured. One-way analysis of variance (ANOVA) and post hoc Tukey HSD tests were used for statistical analysis (α = 0.05). Results: AMD values were significantly lower in group C than in groups D and I (P < 0.05). MG values in group C were significantly lower than those in the buccal and distal areas in group D and all areas in group I (P < 0.05). AI values in the buccal and palatal areas in group D were significantly lower than those in the mesial and distal areas in group D and all areas in groups C and I (P < 0.05). LI values were significantly lower in group C than in groups D and I (P < 0.05). Conclusion: All three methods were clinically acceptable except for the marginal fit of the intraoral scanning and milling method, which was on the borderline of a clinically acceptable fit. (Int J Comput Dent 2023;26(1): 37–0; doi: 10.3290/j.ijcd.b3818305) Keywords: lithium disilicate ceramic, marginal fit, internal fit, press system, CAD/CAM, preparation

Aim: The present study aimed to develop a method for measuring 3D maxillary tooth movement during orthodontic treatment and to verify the accuracy of the method. Materials and methods: A 3D model analysis method was established to measure tooth movement by combining the effects of CBCT and intraoral scans. Transformation matrices were used to abstract the motion features of the teeth and translate them into translations and rotations. To test the validity and reliability of the method for clinical application, the inclination of the central incisor was measured using a 3D model analysis method and cephalometric analysis. Measurement error, correlation, and agreement between the two methods were analyzed using the Dahlberg formula, intraclass correlation coefficient, and Bland-Altman analysis, respectively. The performance of the 3D model analysis method was evaluated by monitoring the canine movement of a patient who underwent a premolar extraction. Results: The measurement error was 0.58 degrees for the 3D model analysis and 2.02 degrees for the cephalometric analysis. There was no significant difference in the central incisor inclination measurements between the cephalometric and the 3D model analyses methods. A high correlation (0.974) and narrow limits of agreement (-3.55 degrees, 4.16 degrees) were obtained between the two methods. Minute movements and additional details of orthodontic tooth movements could be observed using the 3D model analysis method. Conclusion: The 3D model analysis method was reliable and reproducible for clinical application in monitoring the 3D maxillary tooth movement during orthodontic treatment. The trueness should be further evaluated. (Int J Comput Dent 2023;26(1): 49–0; doi: 10.3290/j.ijcd.b3818301) Keywords: orthodontic tooth movement, intraoral scan, computed tomography, digital model, superimposition, transformation matrix

Aim: The aim of the present study was to present the different stages of prosthetic treatment planning involved in the design of an esthetic smile and the improvement of masticatory function using CAD/CAM technology. Materials and methods: The patient underwent the following tests and procedures: CBCT (CS 9300; Carestream), intraoral scans and occlusal detection (CS 3600; Carestream), a photographic portrait session (Nikon D610; Nikon), a face scan (Bellus 3D FaceApp; iPhone XS, Apple), and registration of individual temporomandibular joint (TMJ) angles and mandibular movements with a Zebris for Ceramill device (Amman Girrbach). All the data were transferred to Ceramill Mind software (Amman Girrbach) where they were integrated. The face scan and photographs were superimposed on the CBCT scans. Scans of the dental arches were combined with the CBCT scans. On this CBCT base, the position of the condyles in the articular fossae was determined. A Virtual Artex CR virtual articulator (Amann Girrbach) was attached to the 3D object. Individual TMJ angles and mandibular movements were then introduced. Results: A virtual patient was created in the Ceramill Mind software. The optimal shape and position of each tooth were designed into the program. The wax-up was printed using a 3D printer and a temporary mock-up, and final restorations were made for the patient. At the same time, the esthetics of the smile was improved, and a harmonious central occlusion and articulation were obtained on virtual models and in the patient’s oral cavity. Conclusion: The presented digital planning protocol allows the working out of an optimal solution in complicated patient cases from both the functional and esthetic points of view. (Int J Comput Dent 2023;26(1):61–0; doi: 10.3290/j.ijcd.b2599445) Keywords: CAD/CAM, digital dentistry, CBCT, Zebris for Ceramill, computerized dentistry, esthetic digital planning, digital occlusion and articulation

Digital dentistry has contributed to the evolution and simplification of dental implantology over the last decade. The incorporation of intraoral scanners, CBCT, 3D implant-planning software, and CAD/CAM systems makes prosthetically driven implantology a straightforward process. Such digital resources for treatment planning and execution, following evidence-based concepts, have the ability to improve the long-term esthetics and function of implant-supported restorations as well the long-term survival of dental implants. Dental implants are frequently considered as the first treatment option for replacing failing or missing teeth. However, their use in the esthetic zone remains a challenge for many clinicians. The present article provides clinical guidelines for ideal implant positioning employing computer-guided surgery and chairside CAD/CAM-fabricated provisional and definitive restorations with titanium (Ti)-bases for successful prosthetic outcomes, optimizing gingival architecture, and decreasing overall treatment duration. (Int J Comput Dent 2023;26(1):75–0; doi: 10.3290/j.ijcd.b3818287) Keywords: Dental implant, implant restoration, chairside, CAD/CAM, titanium base, implant position, immediate provisional, guided implant surgery

Modern dentistry now also means digital dentistry. Conventional processes are being replaced by software-controlled procedures, automation, and the combination of different technologies. The goal is to create safe treatment protocols for excellent and reproducible clinical results. Based on a patient case, the present article demonstrates the essential steps of implant therapy, from digital impression and treatment planning to 3D printing of the surgical guide and guided insertion. (Int J Comput Dent 2023;26(1):89–0; doi: 10.3290/j.ijcd.b3818307) Keywords: digital workflow, digital impression, 3D printing, digital workflow, implant therapy, surgical guide, treatment protocol, guided implant surgery