EditorialPubMed ID (PMID): 36125803Pages 243-244, Language: English, GermanBeuer, Florian
ScienceDOI: 10.3290/j.ijcd.b2599735, PubMed ID (PMID): 35072419Pages 249-256, Language: English, GermanFotopoulos, Ioannis / Lillis, Theodoros / Panagiotidou, Eliza / Kapagiannidis, Ioannis / Nazaroglou, Ioannis / Dabarakis, Nikolaos
Aim: The purpose of the present study was to report early surgical template-related and postoperative complications of computer-guided implant placement and to evaluate its accuracy.
Materials and methods: Data were collected retrospectively from records of patients who had undergone computer-guided implant surgery between 2016 and 2018. Incidence of early surgical template-related and postoperative complications was recorded. Accuracy of implant placement was evaluated by comparing the data from postoperative CBCT records with that from the preoperative virtual implant planning by using appropriate image registration software. Depth, coronal, apical, and angular deviations were measured.
Results: A final number of 27 partially edentulous patients who received 52 implants with 31 static surgical templates were included in the study. All implants had been inserted in a fully guided manner using a flapless technique and following a one-stage approach. All implants were reported to have been successfully osseointegrated. Except for one template fracture, no other complication was recorded. The mean depth deviation was 0.57 ± 0.4 mm (95% CI 0.48 to 0.71 mm), the mean coronal deviation was 0.89 ± 0.7 mm (95% CI 0.73 to 1.07 mm), the mean apical deviation was 1.4 ± 1 mm (95% CI 1.16 to 1.71 mm), and the mean angular deviation was 2.74 ± 1.8 degrees (95% CI 2.29 to 3.26 degrees).
Conclusion: The use of static surgical templates for fully guided implant placement demonstrated acceptable clinical performance. However, there are some factors affecting accuracy that should be considered during implant planning and surgery for further improvement of the technique. (Int J Comput Dent 2022;25(3):249–256; doi: 10.3290/j.ijcd.b2599735)
Keywords: dental implant, guided surgery, accuracy, implant studio, 3Shape, MGUIDE, 3D printing
ScienceDOI: 10.3290/j.ijcd.b2599691, PubMed ID (PMID): 35072421Pages 257-265, Language: English, GermanYou, Ran / Han, Fei / Sun, Zhida / Xie, Haifeng / Chen, Chen
Aim: The present study aimed to determine the impact of different degrees of salivary contamination and variations in occlusal force during intraoral scanning of inlay/onlay cavities on the accuracy of fine structure reconstruction and occlusal records.
Materials and methods: Digital data of inlay/onlay models, collected using an intraoral scanner, were divided into 40 groups according to the restoration type (onlay or inlay), salivary contamination level (none, completely dry; mild, moist but not visually completely apparent; moderate, half-filled cavity; severe, filled-up cavity), and simulated occlusal force (0, 2, 4, 6 or 8 kg). The acquired 120 datasets were used to measure the average interocclusal space and cavity buccolingual internal angle.
Results: Salivary contamination and occlusal force did affect the occlusal contact (P < 0.001), but restoration type did not (P > 0.05). An interaction was found between inlay type and salivary contamination (P < 0.001), but not between occlusal force and salivary contamination (P > 0.05). Salivary contamination also affected the accuracy of fine structure reconstruction (P < 0.001), but restoration type did not (P > 0.05), and no interaction was found between the two factors (P > 0.05). The difference in the measured internal angle increased with the increase in salivary contamination.
Conclusions: Intraoral optical scanning of inlay/onlay preparations was reliable for recording occlusal contact but showed uncertainty in cavity fine structure reconstruction when moderate or severe salivary contamination was present in the cavity. Nevertheless, a moist cavity surface with no visually apparent salivary contamination is acceptable. (Int J Comput Dent 2022;25(3):257–265; doi: 10.3290/j.ijcd.b2599691)
Keywords: intraoral optical scanning, digital impression, occlusal contact, occlusal force simulation, internal angle measure, CAD/CAM, three-dimensional reconstruction, salivary contamination
ScienceDOI: 10.3290/j.ijcd.b2599709, PubMed ID (PMID): 35072420Pages 267-276, Language: English, GermanRuan, Wenhao / Zheng, Ziting / Jiang, Lifang / He, Jiahui / Sun, Jieli / Yan, Wenjuan
Aim: The present in vitro study aimed to evaluate the stress distribution patterns, resistance to fracture, and failure modes of endodontically treated molars restored with different cuspal coverage options.
Materials and methods: Three-dimensional models of mandibular first molars with six kinds of typical cuspal coverage were generated: T1: mesiobuccal cuspal coverage; T2: coverage of all buccal cusps; T3: mesiolingual cuspal coverage; T4: coverage of all lingual cusps; T5: mesiobuccal and mesiolingual cuspal coverage; T6: coverage of all cusps. All restorations were fabricated with zirconia-reinforced lithium silicate ceramic. The stress and its distributions under axial and oblique loading were analyzed by finite element analysis (FEA). Sixty human mandibular molar samples were randomly allocated into six groups (n = 10) to simulate the application of six types of restorations with different cuspal coverage, as in the FEA analysis, and were then subjected to a compressive test. All fractured specimens were subjected to fractography. Data were analyzed by one-way analysis of variance (ANOVA), the Tukey post hoc test, and the Fisher exact test (α = 0.05).
Results: The T2 and T6 groups presented superior stress distribution patterns under both axial and oblique loading compared with the other models. The fracture loads in the T2 (1627 ± 358 N) and T6 (1639 ± 355 N) groups were significantly higher than those in the other groups (P < 0.05). The T2 and T6 groups exhibited more restorable failure modes. Fractography showed more cracks below the cementoenamel junction in the T3, T4, and T5 groups.
Conclusions: Onlay restorations with whole functional cuspal coverage provided comparable effects to coverage of all cusps in endodontically treated molars, and both methods exhibited a more even stress distribution and fracture resistance and better mechanical performance in high occlusal areas than other types of cuspal coverage. (Int J Comput Dent 2022;25(3):267–276; doi: 10.3290/j.ijcd.b2599709)
Keywords: cuspal coverage, onlay, endocrown, endodontically treated teeth, FEA, CAD/CAM
ScienceDOI: 10.3290/j.ijcd.b2588153, PubMed ID (PMID): 35060370Pages 277-285, Language: English, GermanMoslemian, Naeime / Koulivand, Soudabeh / Zeighami, Somayeh / Nankali, Ali / Alikhasi, Marzieh
Aim: The present study aimed to evaluate the effect of the milling mode and margin defining method on the marginal and internal adaptation of digitally designed and fabricated ceramic veneers.
Materials and methods: Forty extracted central incisors were prepared for ceramic veneers. The veneers were categorized into four groups (n = 10) based on the milling mode (fine or extra-fine) and design (automatic or manual defining of cervical and incisal margins). The veneers were cemented to the teeth using resin cement and then polished. After cementation, the teeth were embedded in clear polyester resin, then cut into three sections. Absolute marginal gap at the cervical margins (AMGC), marginal gap at the incisal (MGI) and cervical (MGC) margins, and internal gap (IG) at the axial wall were evaluated using a scanning electron microscope. Two-way analysis of variance (ANOVA) and t tests were used (α = 0.05) for the statistical analysis.
Results: The margin defining method affected the adaptation of the internal and incisal margin; the automatic (software) margin defining method resulted in a smaller MGI (P = 0.038) and IG (P = 0.009) than the manual defining method.
Conclusion: The type of milling mode did not affect the marginal gap. The margin defining method affected the marginal gap at the incisal margin and the internal gaps. (Int J Comput Dent 2022;25(3):277–285; doi: 10.3290/j.ijcd.b2588153)
Keywords: veneer, margin defining, SEM, CAD/CAM, marginal adaptation, ceramic
ScienceDOI: 10.3290/j.ijcd.b2599661, PubMed ID (PMID): 35072422Pages 287-294, Language: English, GermanZou, Yun / Zhan, DeSong / Xiang, JingZhou / Li, Ly
Objective: To assess the clinical status of monolithic zirconia CAD/CAM endocrowns and crowns on post and core buildups in endodontically treated molars after 5 years of clinical service.
Materials and methods: A total of 670 patients who received restorations for excessive defects at Ansteel Group Hospital from 2012 to 2015 were selected and randomly divided into two groups: 334 patients in the endocrown group and 336 in the post and core crown group. All the treatments were performed using a digital CAD/CAM system. The prostheses restorations at 1, 3, and 5 years after treatment were evaluated using the USPHS (United States Public Health Service) criteria and satisfaction questionnaire. In addition, the time cost of tooth preparation was recorded by the clinicians.
Results: Most of the patients in both groups reported grade A at the after-treatment follow-ups. Gingival health, food impaction, marginal accuracy, and general satisfaction at 3 and 5 years after treatment in the endocrown group rated higher (P < 0.05) than in the post and core crown group. There was no statistical difference in other indicators between the two groups at all observational after-treatment timepoints (P > 0.05). The time cost of tooth preparation in the post and core crown group was significantly higher than that in the endocrown group.
Conclusion: A CAD/CAM scanning system combined with a monolithic zirconia endocrown restoration was rated very positively by the participants. Endocrown restorations are a significantly superior choice compared with post and core crowns in clinical application. (Int J Comput Dent 2022;25(3):287–294; doi: 10.3290/j.ijcd.b2599661)
Keywords: monolithic zirconia endocrowns, crowns on post and core buildups, CAD/CAM fabrication
ScienceDOI: 10.3290/j.ijcd.b2599775, PubMed ID (PMID): 35072417Pages 295-302, Language: English, GermanKoch, Petra Julia / Albrecht, Marco / Lin, Wei-Cheng / Jost-Brinkmann, Paul-Georg
Ziel: Vorstellen eines Algorithmus zur Messung der Genauigkeit von Übertragungsschienen für das indirekte Kleben von Brackets und dessen Anwendung für die Analyse einer CAD/CAM-basierten Übertragungsschiene.
Material und Methode: Gipsmodelle von 24 Patienten mit vollständig bleibender Dentition und unterschiedlichen Zahnfehlstellungen wurden mit einem Intraoralscanner (TRIOS®, 3Shape) digitalisiert, um sie in die Planungssoftware OnyxCeph³™ (Image Instruments) als digitale Modelle einzupflegen. Anschließend wurden darauf im softwareintegrierten FA-Bonding Modul Brackets und Röhrchen virtuell auf alle Zähne platziert und die digitalen Modelle samt Planung der Bracketpositionen an CA Digital gesandt für das Herstellen der INDIVIDUA® Übertragungsschiene (CA Digital). Nach Erhalt der CAD/CAM-basierten Schiene wurden die Brackets und Röhrchen (discovery® smart/pearl, Dentaurum) mithilfe dieser Übertragungsschiene auf die entsprechenden Gipsmodelle im indirekten Verfahren geklebt und deren Position mit einem zweiten Intraoralscan erfasst. Eine Analyse der Abweichungen zwischen der digital geplanten und der tatsächlichen Position der Brackets und Röhrchen erfolgte automatisiert in der Prüfsoftware Geomagic Control® (3D Systems Inc.) mithilfe eines darin eingepflegten Algorithmus, der die Oberfläche der einzelnen Zähne mit einer lokalen Best-fit-Anpassung überlagerte. Für jedes Bracket und Röhrchen wurden die Abweichungen in drei linearen und drei angularen Dimensionen berechnet und interpretiert.
Ergebnisse: Der vorgestellte Algorithmus analysierte erfolgreich die Genauigkeit der CAD/CAM-basierten Übertragungsschiene für das indirekte Kleben von Brackets und Röhrchen. Mit der beispielhaft evaluierten INDIVIDUA® Übertragungsschiene wurden insgesamt 622 Brackets und Röhrchen in einem digitalen Workflow auf entsprechende Gipsmodelle übertragen. Dabei lagen 98,3 % der linearen und 86,7 % der angularen Messwerte im klinisch akzeptablen Bereich, welcher vom American Board of Orthodontics definiert wurde.
Schlussfolgerung: Es wurde ein Algorithmus vorgestellt, der die Genauigkeit von Übertragungsschienen für das indirekte Kleben von Brackets und Röhrchen erfolgreich und automatisiert analysieren kann. Beispielhaft wurde die Genauigkeit der INDIVIDUA® Übertragungsschiene evaluiert und diese als klinisch einsetzbare Alternative zu konventionellen Schienen bewertet.
Keywords: Digitale Kieferorthopädie, digitaler Workflow, indirektes Kleben von Brackets, CAD/CAM, Übertragungsschiene, Genauigkeit, automatisierte 3-D-Überlagerung, Algorithmus
ApplicationDOI: 10.3290/j.ijcd.b3380919, PubMed ID (PMID): 36125804Pages 303-323, Language: English, GermanNorré, David / Att, Wael
The digital workflow in implant dentistry aims to provide safer and predictable implant placement. This is facilitated through visualization of the anatomical structures as well as the integration of the prosthetic information to dictate implant placement. Guided surgery is useful in edentulous arches planned for fixed rehabilitations, where the unfavorable position of the implants may limit the possibility to realize such a treatment option. In full-arch immediate implant placement and immediate loading, computer-guided implant surgery gains a significant importance. Here, clinicians rely on either soft tissue or bone to provide support for the surgical guide during implant placement. Due to tooth extraction and the loss of anatomical structures that improve the support of the surgical guide, the correct positioning of the guide can be challenging. Further, the procedure that follows to deliver the immediate temporary rehabilitation can also be challenging due to the lack of workflow integrity between the surgical and restorative phases. The present case report describes a novel digital workflow for immediate implant placement and immediate loading of a full-arch rehabilitation, which aims to improve the accuracy of implant placement surgery and simplify the procedure of delivering immediate provisional restorations. (Int J Comput Dent 2022;25(3):303–323; doi: 10.3290/j.ijcd.b3380919)
Keywords: immediate loading, guided implant placement, virtual planning, surgical guide, prosthetic guide, digital implantology
ApplicationDOI: 10.3290/j.ijcd.b3380909, PubMed ID (PMID): 36125805Pages 325-332, Language: English, GermanHöhne, Christian / Schmitter, Marc
Aim: With the development of new materials, 3D printing has had an immense impact on dentistry. The latest innovations are the direct manufacturing of temporary and permanent crown and bridge restorations, inlays, onlays, and veneers. In the present case report, 3D-printing technology was used to control and adjust the occlusal rehabilitation with 3D-printed crowns.
Materials and methods: A 44-year-old male patient with pathologic dental attrition visited the Department of Restorative Dentistry at the University of Würzburg (Würzburg, Germany). The attrition process was far advanced, and no conventional conservative therapy was indicated. For the rehabilitation of the tooth substance loss, dental height, and appearance, a permanent solution with dental crowns was elected. After the preparation, the restorations were constructed digitally. For the control of the occlusal height, appearance, and color, the restorations were fabricated with a 3D printer and temporarily cemented. The crowns showed a high precision, and only minimal occlusal corrections were needed. After a trial period of 2 weeks and another fine occlusal adjustment, the temporary crowns were removed and scanned. The data were matched to the original construction file, which could be used to optimize the final rehabilitation. The final restorations were made of monolithic zirconia, with only minimal occlusal corrections required.
Conclusion: At the present time, dentistry is experiencing a great shift toward new and interesting production solutions with 3D-printing technologies. Such technologies give dentists the ability to create more predictable and cost-effective treatments. 3D printing is already being used to create temporary and definitive dental crowns as well as complex treatments, as is shown in the present case report. (Int J Comput Dent 2022;25(3):325–332; doi: 10.3290/j.ijcd.b3380909)
Keywords: digital dentistry, 3D printing, stereolithography, additive manufacturing, rapid prototyping, CAD/CAM, temporary crowns, ceramic restorations, dental prosthetics