EditorialDOI: 10.3290/j.ijcd.b4119815, PubMed ID (PMID): 37232291Pages 111-112, Language: English, GermanBeuer, Florian
ScienceDOI: 10.3290/j.ijcd.b3759621, PubMed ID (PMID): 36602786Pages 117-124, Language: English, GermanTchorz, Jörg Philipp / Gierl, Valentina / Piasecki, Lucila / Frank, Wilhelm / Wrbas, Karl-Thomas
Aim: The purpose of the present investigation was to evaluate the accuracy of root canal length (RCL) determination according to CBCT acquisition protocol and evaluate the influence of additional superimposed computerized optical impressions.
Materials and methods: CBCT scans with low-dose (LD) and high-definition (HD) protocols as well as computerized optical impressions of 30 extracted human molars were acquired. Sicat Endo software (Sicat) was used for CBCT RCL measurements with (LD+, HD+) and without (LD-, HD-) a superimposed optical impression. To evaluate the accuracy, absolute differences between test groups and the actual root canal length (ARCL) were calculated and statistically analyzed using the Wilcoxon rank sum test.
Results: Absolute differences between the ARCL and the tested measurement methods varied significantly (P < 0.05). Both higher resolution and additionally superimposed computerized optical impression improved measurement accuracy. Mean differences compared with the ARCL were 0.26 mm (HD+), 0.34 mm (HD-), 0.43 mm (LD+), and 0.66 mm (LD-). 93.4% of all measurements in the HD+ group were within the limits of ± 0.5 mm.
Conclusion: Both resolution and superimposition of additional computerized optical impressions have a significant influence on RCL measurements using CBCT.
Keywords: CBCT, computerized optical impression, root canal length determination, Sicat Endo
ScienceDOI: 10.3290/j.ijcd.b3759633, PubMed ID (PMID): 36602787Pages 125-136, Language: English, GermanRatzmann, Anja / Weßling, Mathias / Krey, Karl-Friedrich
Aim: Orthodontic treatments with custom-made active elements may lead to more efficient treatment with fewer side effects. The objective of the present in vitro study was to determine whether individually constructed, mathematically simulated, and 3D-printed power chains could generate adequate forces for orthodontic tooth movement.
Materials and methods: An individual measurement device was developed using a high-precision load cell, amplifier, and microcontroller for signal processing. Elastic chains were designed and subsequently printed from two different thermoplastic polyurethane (TPU) filaments and a thermoplastic elastomer (TPE) filament. With the CAD data, a finite element analysis (FEA) was performed to calculate the reactive forces to be expected at different activation levels. The measured force development of the test objects was compared with the results from the FEA.
Results: The results showed a high precision of the measurement device, with an intraclass correlation coefficient (ICC) of 0.999 and a Dahlberg error of 0.05 N. The measured forces ranged from 196 to 681 g. There was a significant correlation between the measured and calculated forces (R 0.91 to 0.98).
Discussion: In the present study, the fully digital workflow of producing an individualized active orthodontic treatment element, which developed almost exactly the force values calculated in the FEA, was shown. Future clinical use seems promising, in combination with fully individualized and digitally planned treatment approaches. This offers the possibility to integrate these insights from exemplary applications into patient-specific digital planning in orthodontics. The combination of CBCT root reconstruction, intraoral scans with customized brackets, and wires is the perfect starting point to add mechanical and numerical simulations. This would be the next step from shape-driven planning to force-driven planning. The goal is to reduce treatment time and negative side effects, eg, root resorption.
Conclusion: The present in vitro study is the first to show the possible individualized construction and 3D printing of elastic chains exhibiting reproducible, predefined forces.
Keywords: rubber chain, power chain, custom active element, orthodontics, CAD/CAM, 3D printing, finite element analysis
ScienceDOI: 10.3290/j.ijcd.b3762753, PubMed ID (PMID): 36607263Pages 137-148, Language: English, GermanHerklotz, Insa / Beuer, Florian / Bruhnke, Maria / Zoske, Jan / Böse, Mats Wernfried Heinrich
Aim: To compare the planned implant position (PIP) with the transferred implant position (TIP) after fully guided implant placements in single-tooth gaps.
Materials and methods: Dental implant placements were planned using two different implant systems (Camlog Screw-Line [C-SL] and Straumann Bone Level Tapered [S-BLT]), and two different planning software programs (SMOP and coDiagnostiX). All implants were placed according to fully guided protocols, and intraoral scans were performed intraoperatively. For the comparison of PIP and TIP, scan data were imported to Geomagic Control X (GCX) software and accuracies were evaluated. Deviations were reported in a coordinate system (x- [mesiodistal], y- [vestibulo-oral], and z- [vertical] axis) at entry points and apices. Total deviations, including angular deviations, were calculated with GCX. For statistical analysis, the level of significance was set to P < 0.05.
Results: Twenty-six patients received 26 implants. Mean 3D deviation at the implant’s entry point was 0.61 mm ± 0.28 for C-SL and 0.63 mm ± 0.24 for S-BLT. For the implant’s apex, mean 3D deviation of 0.96 mm ± 0.41 was documented for C-SL and 1.04 mm ± 0.34 for S-BLT. Mean angular deviation was 2.58 degrees ± 1.40 for C-SL and 2.89 degrees ± 1.12 for S-BLT. Statistical analysis revealed no significant differences between implant systems, but showed significant deviations regarding the z-axis, both at entry point and apex (P < 0.05).
Conclusions: Fully guided implant placements in single-tooth gaps provide accurate results. Due to significant vertical deviations, reevaluation of both drilling and insertion depths prior to implant installation should be considered. Maintenance of 1.5- to 2-mm safety distances to critical structures was confirmed.
Keywords: dental implants, static navigation, CAD/CAM, computer-assisted, computer-assisted implant surgery, backward planning
ScienceDOI: 10.3290/j.ijcd.b3762733, PubMed ID (PMID): 36607264Pages 149-158, Language: English, GermanSchubert, Oliver / Graf, Tobias / Schweiger, Josef / Güth, Jan-Frederik / Sciuk, Thomas / Erdelt, Kurt-Jürgen
Aim: The CAM of esthetically pleasing monolithic dental restorations presents with specific challenges. One vital parameter to consider is the translucency of the materials. Previous studies have proven a correlation between translucency and material thickness for various all-ceramic materials. The aim of the present study was to assess and define the relationship between thickness and translucency in modern resin-based restorative materials.
Materials and methods: Specimens fabricated from two resin nano-ceramics (Cerasmart, Lava Ultimate), a polymer-infiltrated ceramic network (Vita Enamic), and a polymethyl methacrylate (Telio CAD) were examined, representing these different material classes. For each material, 12 specimens (n = 12) were fabricated in five thicknesses (0.4, 0.7, 1.0, 1.3, and 1.6 mm; N = 240). The translucency was measured with a spectrophotometer. The total light transmittance for each specimen was calculated applying specialized software. Regression curves were fitted to the results and their coefficient of determination (R2) fit was determined.
Results: Logarithmic regression curves showed the best R2 approximation (Cerasmart: R2 = 0.994; Vita Enamic: R2 = 0.978; Lava Ultimate: R2 = 0.997; Telio CAD: R2 = 0.997) to the light transmission values.
Conclusions: The results of the present study indicate that the translucency of resin-based materials can be calculated using a mathematic approach to estimate their optical behavior. Cerasmart, Lava Ultimate, Vita Enamic, and Telio CAD exhibit a logarithmic relationship between material thickness and translucency. By determining material-specific coefficients for this logarithmic function, the resulting translucency can be computed for any given material thickness.
Keywords: hybrid materials, PMMA, polymer-infiltrated ceramic network, resin nano-ceramics, translucency, translucency equation, mathematic analysis, CAD/CAM, digital workflow
ScienceDOI: 10.3290/j.ijcd.b3759607, PubMed ID (PMID): 36602785Pages 159-166, Language: English, GermanBauer, Robert / Zacher, Julian / Strasser, Thomas / Schmid, Alois / Rosentritt, Martin
Ziel: Ziel der vorliegenden Studie war es, die In-vitro-Bewährung und Bruchlast für 3-D-gedruckte provisorische implantatgetragene Frontzahnbrücken aus Materialien mit unterschiedlichem Füllstoffgehalt zu untersuchen.
Material und Methode: Aus verschiedenen Methacrylat-Kunststoffen mit unterschiedlichem Füllstoffgehalt wurden identische implantatgetragene Frontzahnbrücken (Regionen 11 bis 13, n = 8 je Material) gedruckt. Ein Kartuschen-PMMAMaterial diente als Referenz. Die Brücken wurden provisorisch zementiert und einer zyklischen thermomechanischen Ermüdung unterzogen, um den klinischen Einsatz zu simulieren. Die Bewährung während der Ermüdung und die Bruchlast wurden bestimmt und die Bruchtypen analysiert. Schließlich wurden die gewonnenen Daten statistisch analysiert (Kolmogorow-Smirnow-Test, einfaktorielle Varianzanalyse, Bonferroni-Korrektur, Kaplan-Meier-Schätzer, α = 0,05).
Ergebnisse: Die Anzahl der Ausfälle während der thermomechanischen Ermüdung variierte zwischen 3 Proben und allen 8 Proben pro Gruppe während der Belastungsphase. Die mittlere Überlebensdauer lag im Bereich von 93 ± 206 x 103 und 329 ± 84 x 103 Zyklen. Zwischen den getesteten Materialien bestanden signifikante Unterschiede hinsichtlich der Anzahl überlebter Zyklen (Mantel-Cox-Logrank-Test: Chi-Quadrat = 21,861, Freiheitsgrade = 4, p < 0,001). Es fand sich eine Korrelation zwischen dem Füllstoffgehalt und den Überlebenszyklen (Pearson-Korrelation = 0,186, p = 0,065). Die Bruchlasten der überlebenden Brücken lagen bei 499 bis 835 N. Die Ausfälle waren an erster Stelle durch Verbinderfrakturen bedingt (n = 24), gefolgt von Frakturen am Abutment (n = 10).
Schlussfolgerung: Das Überleben provisorischer Brücken war abhängig vom Füllstoffgehalt des Brückenmaterials. Die individuell 3-D-gedruckten Materialien zeigten eine vergleichbare oder bessere Bewährung als das Standardmaterial aus der Kartusche und dürften für provisorische Versorgungen mit Einsatzzeiten von einem halben Jahr und mehr geeignet sein.
Keywords: Rapid Prototyping, 3-D-Druck, additive Fertigung, Interimsprothetik, thermomechanische Ermüdung, Finite-Elemente-Analyse, provisorische Brücke, Implantat
ScienceDOI: 10.3290/j.ijcd.b3762767, PubMed ID (PMID): 36607265Pages 167-174, Language: English, GermanMönnink, Carolin / Eich, Lukas / Haddadin, Sami / Stiesch, Meike / Grischke, Jasmin
Aim: The aim of the present study was to compare the performance of a tactile collaborative robot programmed by a dental professional (DP) with that of a DP in the removal of surrogate plaque in vitro.
Materials and methods: Six typodont teeth in articulated jaws were covered with surrogate plaque and cleaned by a DP with the help of a manual toothbrush (DP/manual) and an electric toothbrush (DP/electric). The experiment was repeated with the help of a collaborative seven-axis tactile robot programmed by a DP handling a manual toothbrush (robot/manual) and an electric toothbrush (robot/electric). All experiments were repeated five times, resulting in a total of N = 30 teeth in each group. Cleaning results were reported as the percentage of surface area with residual plaque.
Results: The cleaning results of the DP and the robot showed no significant differences. However, electric toothbrushing was significantly less effective compared with manual toothbrushing (P < 0.05).
Conclusion: The present in vitro study indicates that current robot technology may perform the removal of surrogate plaque as efficiently as a DP. In future, this may be helpful to release nursing staff from this time-demanding task that could possibly cause contagion or to support people with reduced motor skills or impaired vision in performing daily oral hygiene.
Keywords: dentronics, robotics, dentistry, dental robots, oral hygiene, electric toothbrush, manual toothbrush, human-machine interaction, human-robot interaction
ApplicationDOI: 10.3290/j.ijcd.b3799799, PubMed ID (PMID): 36632985Pages 175-182, Language: English, GermanHanisch, Marcel / Wagner, Basti / Schuh, Paul
Clinical case study and practical adviceSurgical crown lengthening is one of the most common surgical procedures in periodontal practice. It is divided into functional and esthetic surgical crown lengthening. In general, surgical crown lengthening is a predictable periodontal surgical procedure. Its most common complication is excessive regression of the dentoalveolar complex coronally. Esthetic surgical crown lengthening can be performed predictably through prior digital planning, minimizing the risk of potential complications such as excessive regression of the dentoalveolar complex coronally. The present study reported in this article is a clinical case of surgical crown lengthening with digital planning to derive practical recommendations.
Keywords: surgical crown lengthening, digital planning, esthetics