EditorialPubMed ID (PMID): 35851353Pages 119-120, Language: English, GermanBeuer, Florian
ScienceDOI: 10.3290/j.ijcd.b2588185, PubMed ID (PMID): 35060372Pages 125-132, Language: English, GermanTatis, Diego Fernando / Medina, Claudia Ximena / Delgado, Diego / Agudelo, Fahuslly Issa / Wallis, Luis Samuel / García, Kevin Chica / Osorio, Adrián Fernández
Aim: Increased vertical growth of the maxilla is a condition that affects a large part of the population. The condition reveals a skeletal alteration of the cranio-masticatory system. One of the effects generated by the excessive vertical growth of the maxilla is a gingival smile pattern that can affect esthetic patterns as well as alter the masticatory biomechanics, which is a primary etiologic factor in temporomandibular dysfunction (TMD). Contemporary imaging aids help to optimize diagnostic analysis; perform treatment; and make an evaluation before, during, and after treatment. The present study aims to compare the clinical diagnosis of gingival smile with the dimensions of the dentoalveolar square, digitally calculated in the panoramic projection of the CBCT.
Materials and methods: In a sample of 37 patients, an analysis was performed of the correlation between the dimensions of the dentoalveolar square of the Tatis panoramic cephalometry and the clinical photometry, applying the Tjan gingival smile analysis.
Results: The results show that there is high correlation and agreement between the cephalometric measurement method of the dentoalveolar square and Tjan’s photometric measurement method. Both methods can be used to classify the smile type as high, medium or low.
Conclusions: Analysis of the dentoalveolar square of the panoramic cephalometry provides an accurate diagnosis of the anterior vertical dimension of the maxilla as it relates to the clinical diagnosis of smile.
Keywords: gingival smile, panoramic radiography, maxillary height, smile analysis, maxillary vertical dimension
ScienceDOI: 10.3290/j.ijcd.b2585503, PubMed ID (PMID): 35060368Pages 133-139, Language: English, GermanPetrie, Cynthia S. / Hayes, Katherine / Scott, JoAnna M. / Walker, Mary P.
Aim: The purpose of the present study was to investigate the effectiveness of digital impressions made by 3rd and 4th year dental students using a retrospective record review at one USA dental school during a 1-year period.
Materials and methods: After reviewing patient records related to quality assurance, 125 digital impressions and the produced restorations were evaluated. Effectiveness and acceptability of digital impressions and restorations were associated with students’ educational level, number of prepared teeth scanned, type of produced restoration, and restorative material used. Fisher’s exact and chi-square tests were used for the statistical analysis. All dental students had previous experience of the digital curriculum in their preclinical education.
Results: A total of 91% of the digital impressions were acceptable, and 80% of the produced restorations had clinically acceptable margins. Impression approval and restoration acceptance were not affected by students’ educational level, number of preparations or restoration type. Restoration acceptance was significantly affected by restorative material (P = 0.039), with higher rates of acceptable marginal integrity found with glass-ceramic and zirconia materials.
Conclusions: Within the parameters of the present study, 3rd and 4th year dental students, after having extensive education in the preclinical curriculum, can utilize digital impressions effectively for clinical practice. The results show that with adequate educational experiences, dental students can use digital impressions effectively for clinically acceptable restorations. Dental schools can and should educate students in digital dentistry.
Keywords: digital dentistry, digital imagining, digital impressions, CAD/CAM, intraoral scanners
ScienceDOI: 10.3290/j.ijcd.b2588203, PubMed ID (PMID): 35060373Pages 141-150, Language: English, GermanQin, Wenlong / Cong, Ming / Liu, Dong / Ren, Xiang
Aim: The full-contact model has been widely used in tooth preparation and prosthesis fabrication. However, it is rarely used in denture tests. The purpose of the present study was to design a suitable full-contact dental model for denture tests.
Materials and methods: A standard dental model with the complete tooth morphology was raster scanned and 3D reconstructed. Then, the positioning and fixing surfaces of the dental model were reshaped. The dental model was digitally trimmed into two parts: a fundamental part and a replaceable part. The modular design was presented according to dentition defects around the first molar. The prepared tooth replicas were designed through preparation/scanning/registration/separation sequences. The dental model was fabricated by stereolithography (SLA) 3D-printing rapid prototype technology. The static fracture force of the dental model was predicted using the finite element method. The effects of the four design methods on the suitability of the five testing operations (abutment fabrication, prosthesis fabrication, assembling, loading, and observation) were quantitatively analyzed. The static tests of three fixed partial dentures (FPDs), including tooth-supported, implant-supported, and tooth–tooth-supported prostheses, were conducted to investigate the fracture feature. The dynamic test of a removable partial denture (RPD) was undertaken to study the wear characteristic.
Results: The dental model could bear the maximum fracture strength of 4268.3 N. Seven positive and two negative effects of the design methods were produced. The maximum fracture strength of the FPDs were 1331.2 N, 1356.7 N, and 1987.7 N. The wear facets of the RPD in the dynamic denture test were distributed in three regions.
Conclusions: The force capacity of the full-contact dental model allows the application of static denture tests. The dental model provides improvements in fixture design, removable design, and replica design for the testing operations. The dental model is recommended more in the dynamic test than in the static test.
Keywords: dental model, denture test, computer-assisted design, 3D printing, computer-assisted analysis
ScienceDOI: 10.3290/j.ijcd.b2588131, PubMed ID (PMID): 35060369Pages 151-159, Language: English, GermanSchubert, Oliver / Edelhoff, Daniel / Erdelt, Kurt-Jürgen / Nold, Ephraim / Güth, Jan-Frederik
Aim: Milling-based, subtractive fabrication of digital complete dentures represents the computer-engineered manufacturing method of choice. However, efficient additive manufacturing technologies might also prove beneficial for the indication. The aim of the present study was to evaluate the accuracy of surface adaptation of complete denture bases fabricated using subtractive, additive, and conventional manufacturing techniques.
Materials and methods: A standardized edentulous maxillary model was digitally designed and milled. Twelve duplicated plaster casts were scanned and virtual denture bases designed accordingly. Physical complete denture bases (n = 12 per technique) were manufactured applying different digital and conventional fabrication methods: 1) CNC milling (MIL); 2) material jetting (MJ); 3) selective laser sintering (SLS); 4) digital light processing (DLP); and 5) conventional injection molding (INJ). The INJ group served as control. The intaglio surfaces of the denture bases were digitized and superposed with the surface data of the casts using a best-fit algorithm. Accuracy of surface adaptation was assessed by examining deviations. Statistical analysis was conducted using SPSS (P < 0.05).
Results: The milling of denture bases led to significantly better surface adaptation compared with all the other technologies (P < 0.001). The other fabrication methods in the study, including conventional manufacturing, revealed no considerable overall differences.
Conclusions: As regards the accuracy of surface adaptation, all the investigated technologies adequately produced complete denture bases, with milled denture bases presenting the most superior results.
Keywords: 3D printing, additive manufacturing, CAD/CAM, digital complete denture, digital light processing, denture fit, material jetting, milling, PolyJet technology, selective laser sintering
SciencePubMed ID (PMID): 35851354Pages 161-172, Language: English, GermanHerstell, Hannah / Berndt, Saskia / Kühne, Christina / Reich, Sven
Ziel: Ziel war es, vier Messmethoden für die Bewertung von Abweichungen zwischen geplanter und tatsächlicher Implantatposition nach Implantatsetzung im digitalen Workflow unter Verwendung 3-D-gedruckter Implantatschablonen zu untersuchen.
Material und Methode: In einem volldigitalen Workflow wurden Einzelimplantat-Insertionen zum Ersatz eines oberen mittleren Schneidzahns und ersten Molaren an 10 Gipsmodellen (n = 10) simuliert. Die Operationsschablonen (n = 10 je Stelle) für die Implantatbettpräparation und Implantatinsertion wurden mittels Digital Light Processing hergestellt. Zur Analyse der Abweichungen zwischen der geplanten und der tatsächlich erreichten Implantatposition wurden vier Methoden eingesetzt: Die Methoden 1 und 2 verwendeten eine Software, um die Abweichungen zwischen den initialen Planungsdaten und den Daten der tatsächlichen Implantatposition bezogen auf das Implantatbett (Methode 1) bzw. das inserierte Implantat (Methode 2) automatisch zu ermitteln. Für Methode 3 wurde ein STL-Datensatz der tatsächlichen Implantatposition verwendet und mit Referenzebenen versehen. Dieser Datensatz wurde so zu den Planungsdaten ausgerichtet dass, die Abweichungen manuell gemessen werden konnten. Methode 4 verwendete ein auf hochauflösenden 3-D-Scans basierendes Reverse-Engineering-Verfahren.
Ergebnisse: Die mittleren räumlichen Abweichungen lagen für das Frontzahnimplantat an der Implantatschulter zwischen 0,26 ± 0,11 mm (Methode 4) und 0,40 ± 0,09 mm (Methode 1), am Implantatapex zwischen 0,52 ± 0,24 mm (Methode 4) und 0,91 ± 0,24 mm (Methode 1) und für die Winkelabweichung zwischen 1,68° und 2,35°. Zwischen den Implantatlokalisationen ergaben sich keine signifikanten Differenzen, während sich zwischen einigen der Bewertungsmethoden signifikante Differenzen bezüglich Implantatschulter und -apex ergaben.
Schlussfolgerung: Die auf Reverse-Engineering basierende Methode 4 ermittelte die geringsten Abweichungen zwischen geplanter und tatsächlicher Implantatposition. Die Werte für die räumlichen Abweichungen der Implantatpositionen waren vergleichbar mit publizierten Werten oder lagen sogar darunter.
Keywords: Digital Light Processing, DLP, 3-D-Druck, statisch geführte computergestützte Implantatchirurgie, s-CAIS, Implantatschablone, Genauigkeit, Richtigkeit, Bewertungsmethode
SciencePubMed ID (PMID): 35851355Pages 173-180, Language: English, GermanHennen, Melina Vivien / Blum, Hannah / Dammaschke, Till
Aim: The accuracy and reproducibility of occlusal contact points visualized by articulating foil (AF) were investigated and then compared with those calculated by three different intraoral scanners (IOSs).
Materials and methods: Occlusal contact points were visualized on a standardized resin dental tooth model using AF 50 times in maximum intercuspation and with a constant biting force. The occlusal contact points were photographed from a vertical position above the model and superimposed on a screen to test the reproducibility of the model. This was followed by 50-fold repetition by scans and computation of the occlusal contact points by three different IOSs: CS 3600 (CS ScanFlow v.1, 4th version), Trios 3 (Basic 2019), and Cerec Omnicam (software version 5.1). The results of the computation were captured with screenshots and were then overlaid with the photographs of the AF. The image overlays were classified into five categories: 1 = total overlapping of contact points, 2 = partial overlapping of contact points, 3 = adjacent contact points without overlapping, 4 = contact points identified only by AF, 5 = contact points identified only by IOS. All data were statistically evaluated (95% confidence interval).
Results: In total, the visualization of the occlusal contact points by the IOSs were significantly less accurate and less reproducible compared with the AF (P < 0.05). When sensitivity and accuracy were combined, the Trios 3 (3Shape) showed significantly better results than the other IOSs tested (P < 0.05).
Conclusion: In vitro, AF displayed a significantly more accurate visualization of the occlusal contact points than the IOSs.
Keywords: articulating foil, digital intraoral scanners, occlusion, occlusal contact point, reproducibility, visualization
ApplicationPubMed ID (PMID): 35851356Pages 181-199, Language: English, GermanRasaie, Vanya / Abduo, Jaafar
The integration of modern technologies in removable prosthodontics in terms of complete denture fabrication has revolutionized fabrication procedures, improved outcomes, and led to advancements in denture materials. Numerous publications have described the digital techniques of complete denture fabrication. The steps described in these publications for the proposed digital workflow are diverse. This is suggestive of the flexibility of these modern techniques in terms of their integration with the steps of conventional protocols. Automated technologies have reduced the need for skilled manual work, while particular knowledge and a new skills set are required for both clinicians and dental technicians. Moreover, the effectiveness and efficacy of these modern technologies in complete denture fabrication are yet to be determined. To consolidate the existing literature on digital techniques of complete denture fabrication, this review summarizes the current digital workflows of the clinical and laboratory stages, describes the digital alternatives in each step, and discusses their advantages and limitations.
Keywords: complete denture, computer-aided design, computer-aided manufacturing, complete digital denture, digital dentistry, edentulous rehabilitation
ApplicationPubMed ID (PMID): 35851357Pages 201-219, Language: English, GermanGuo, Xueqiang / Jiang, Chunmiao / Liu, Xinqiang / Wang, Zheng
Completely digital design/completely digital manufacturing (CDD/CDM) workflows have been widely used in orthodontic and orthognathic treatments. This case report introduces a CDD/CDM workflow consisting of clear aligners and virtual planning for a surgery-first approach (SFA) in a patient with a skeletal Class III malocclusion. Following a shortened treatment time of 5 months, the patient’s facial appearance improved significantly, and well-balanced occlusion was obtained. SFAs with clear aligners can enable patients to achieve complete esthetic satisfaction during the therapeutic period. The CDD/CDM workflow provided accurate results, improved the clinical outcome, and reduced treatment time.
Keywords: surgery-first approach, virtual surgical planning, virtual orthodontic planning, clear aligners, skeletal Class III malocclusion, CAD/CAM
ApplicationPubMed ID (PMID): 35851358Pages 221-231, Language: English, GermanHerklotz, Insa / Kunz, Andreas / Stimmelmayr, Michael / Beuer, Florian
A case reportBackground: Treatment of the edentulous maxilla with a fixed full-arch prosthesis on four immediately loaded implants has been discussed as a treatment option, although generally five implants are recommended for that indication. The precise transfer of the virtually planned position by 3D-guided implant placement is an essential prerequisite for delivering the prefabricated temporary restoration at the time of surgery. Three-point support on the teeth or implants ensures that the template for the guided surgery is soundly seated during the operation.
Case presentation: In the described case, the three-point support was carried out by teeth and temporary implants in the molar region inserted prior to the CBCT. The virtual implant planning determined the best prosthetic implant position while using the available bone to avoid extensive augmentation. Following this, a metal-reinforced provisional restoration was prepared using a drilling template. Four implants were placed in the planned position with the aid of a tooth-/implant-supported guide. The prosthetic axis of the angulated distal implants is balanced by 17-degree angled abutments. After transferring the implant position to the dental laboratory, the prepared restoration was finalized. The remaining teeth were extracted and the temporary restoration was delivered 3 h after implant placement. The definitive fixed full-arch zirconia restoration with micro layering was placed 9 months later in a stable situation.
Conclusion: The remarkable accuracy of the implant placement with a surgical template generated from preoperative virtual implant planning ensures a relatively short treatment time and an uneventful and fast recovery with minimal discomfort. The immediate prosthodontic rehabilitation is a benefit, not only for the patient but also for the dental team. Micro-layered monolithic zirconia seems to be a promising option for screw-retained full-arch prostheses.
Keywords: guided implant surgery, edentulous jaw, backward planning, immediate function, digital workflow