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STATEMENT OF PROBLEM: Multiple factors can influence the accuracy of intraoral scanners (IOSs). However, the impact of scan extension and starting quadrant on the accuracy of IOSs for fabricating tooth-supported crowns remains uncertain. PURPOSE: The purpose of the present in vitro study was to measure the influence of scan extension (half or complete arch scan) and the starting quadrant (same quadrant or contralateral quadrant of the location of the crown preparation) on the accuracy of four IOSs. MATERIAL AND METHODS: A typodont with a crown preparation on the left first molar was digitized (T710) to obtain a reference scan. Four scanner groups were created: TRIOS 5, PrimeScan, i700, and iTero. Then, 3 subgroups were defined based on the scan extension and starting quadrant: half arch (HA subgroup), complete arch scan starting on the left quadrant (CA-same subgroup), and complete arch scan starting on the right quadrant (CA-contralateral subgroup), (n=15). The reference scan was used as a control to measure the root mean square (RMS) error discrepancies with each experimental scan on the tooth preparation, margin of the tooth preparation, and adjacent tooth areas. Two-way ANOVA and pairwise multiple comparisons were used to analyze trueness (α=.05). The Levene and pairwise comparisons using the Wilcoxon Rank sum tests were used to analyze precision (α=.05). RESULTS: For the tooth preparation analysis, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.002). The iTero and TRIOS5 groups obtained better trueness than the PrimeScan and i700 groups (P<.001). Moreover, half arch scans obtained the best trueness, while the CA-contralateral scans obtained the worst trueness (P<.001). The iTero group showed the worst precision among the IOSs tested. For the margin of the tooth preparation evaluation, significant trueness and precision differences were found among the groups (P<.001) and subgroups (P<.001), with a significant interaction group×subgroup (P=.005). The iTero group obtained best trueness (P<.001), but the worst precision (P<.001) among the IOSs tested. Half arch scans obtained the best trueness and precision values. For the adjacent tooth analysis, trueness and precision differences were found among the groups (P<.001) and subgroups tested (P<.001), with a significant interaction group×subgroup (P=.005). The TRIOS 5 obtained the best trueness and precision. Half arch scans obtained the best accuracy. CONCLUSIONS: Scan extension and the starting quadrant impacted the scanning trueness and precision of the IOSs tested. Additionally, the IOSs showed varying scanning discrepancies depending on the scanning area assessed. Half arch scans presented the highest trueness and precision, and the complete arch scans in which the scan started in the contralateral quadrant of where the crown preparation was obtained the worst trueness and precision.
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STATEMENT OF PROBLEM: Maxillary and mandibular scans can be articulated in maximum intercuspal position (MIP) by using an artificial intelligence (AI) based program; however, the accuracy of the AI-based program locating the MIP relationship is unknown. PURPOSE: The purpose of the present clinical study was to assess the accuracy of the MIP relationship located by using 4 intraoral scanners (IOSs) and an AI-based program. MATERIAL AND METHODS: Conventional casts of a participant mounted on an articulator in MIP were digitized (T710). Four groups were created based on the IOS used to record a maxillary and mandibular scan of the participant: TRIOS4, iTero, i700, and PrimeScan. Each pair of nonarticulated scans were duplicated 20 times. Three subgroups were created: IOS, AI-articulated, and AI-IOS-corrected subgroups (n=10). In the IOS-subgroup, 10 duplicated scans were articulated in MIP by using a bilateral occlusal record. In the AI-articulated subgroup, the remaining 10 duplicated scans were articulated in MIP by using an AI-based program (BiteFinder). In the AI-IOS-corrected subgroup, the same AI-based program was used to correct the occlusal collisions of the articulated specimens obtained in the IOS-subgroup. A reverse engineering program (Geomagic Wrap) was used to calculate 36 interlandmark measurements on the digitized articulated casts (control) and each articulated specimen. Two-way ANOVA and pairwise multiple comparison Tukey tests were used to analyze trueness (α=.05). The Levene and pairwise multiple comparison Wilcoxon rank tests were used to analyze precision (α=.05). RESULTS: Significant trueness discrepancies among the groups (P<.001) and subgroups (P<.001) were found, with a significant interaction group×subgroup (P<.001). The Levene test showed significant precision discrepancies among the groups (P<.001) and subgroups (P=.005). The TRIOS4 and iTero groups obtained better trueness and lower precision than the i700 and PrimeScan systems. Additionally, the AI-articulated subgroup showed worse trueness and precision than the IOS and AI-IOS-corrected subgroups. The AI-based program improved the MIP trueness of the scans articulated by using the iTero and PrimeScan systems but reduced the MIP trueness of the articulated scans obtained by using the TRIOS4 and i700. CONCLUSIONS: The trueness and precision of the maxillomandibular relationship was impacted by the IOS system and program used to locate the MIP.
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STATEMENT OF PROBLEM: An artificial-intelligence (AI) based program can be used to articulate scans in maximum intercuspal position (MIP) or correct occlusal collisions of articulated scans at MIP; however, the accuracy of the AI program determining the MIP relationship is unknown. PURPOSE: The purpose of the present clinical study was to assess the influence of intraoral scanner (IOS) (TRIOS 5 or i700) and program (IOS or AI-based program) on the accuracy of the MIP relationship. MATERIAL AND METHODS: Casts of a participant mounted on an articulator were digitized (T710). A maxillary and a mandibular scan of the participant were recorded by using 2 IOSs: TRIOS 5 and i700. The scans were duplicated 15 times. Then, each duplicated pair of scans was articulated in MIP using a bilateral occlusal record. Articulated scans were duplicated and allocated into 2 groups based on the automatic occlusal collisions' correction completed by using the corresponding IOS program: IOS-corrected and IOS-noncorrected group. Three subgroups were created based on the AI-based program (Bite Finder) method: AI-articulated, AI-IOS-corrected, and AI-IOS-noncorrected (n=15). In the AI-articulated subgroup, the nonarticulated scans were imported and articulated. In the AI-IOS-corrected subgroup, the articulated scans obtained in the IOS-corrected group were imported, and the occlusal collisions were corrected. In the AI-IOS-corrected subgroup, the articulated scans obtained in the IOS-noncorrected subgroup were imported, and the occlusal collisions were corrected. A total of 36 interlandmark measurements were calculated on each articulated scan (Geomagic Wrap). The distances computed on the reference scan were used as a reference to calculate the discrepancies with each experimental scan. Nonparametric 2-way ANOVA and pairwise multiple comparison Dwass-Steel-Critchlow-Fligner tests were used to analyze trueness. The general linear model procedure was used to analyze precision (α=.05). RESULTS: Significant maxillomandibular trueness (P=.003) and precision (P<.001) differences were found among the subgroups. The IOS-corrected and IOS-noncorrected (P<.001) and AI-articulated and IOS-noncorrected subgroups (P=.011) were significantly different from each other. The IOS-corrected and AI-articulated subgroups obtained significantly better maxillomandibular trueness and precision than the IOS-noncorrected subgroups. CONCLUSIONS: The IOSs tested obtained similar MIP accuracy; however, the program used to articulate or correct occlusal collusions impacted the accuracy of the MIP relationship.
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The aim of this study was to describe a novel digital technique to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.Materials and methods Ten patients were consecutively included to rehabilitate partial edentulism by dental implants. Both the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were submitted to a digital impression through an intraoral scan to generate a Standard Tessellation Language digital file preoperatively (STL1), at 3 months (STL2), and 6 months (STL3) follow-up. Afterwards, an alignment procedure of the digital files (STL1-STL3) was performed on a reverse engineering morphometric software (3D Geomagic Capture Wrap) and volume changes at the screw-retained implant-supported metal-ceramic dental prostheses and the natural tooth as antagonist were analyzed using Student's t-test. Moreover, Gage R&R statistical analysis was conducted to analyze the repeatability and reproducibility of the digital technique.Results Gage R&R showed a variability attributable to the digital technique of 3.8% (among the measures of each operator) and 4.5% (among operators) of the total variability; resulting repeatable and reproducible, since the variabilities were under 10%. In addition, statistically significant differences were shown at the wear volume (µm3) of both the natural tooth as antagonist (p < 0.0001) and the screw-retained implant-supported metal-ceramic dental prostheses between 3- and 6-months follow-up (p = 0.0002).Conclusion The novel digital measurement technique results repeatable and reproducible to analyze the wear of screw-retained implant-supported metal-ceramic dental prostheses and natural tooth as antagonist.
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Implantes Dentales , Humanos , Proyectos Piloto , Reproducibilidad de los Resultados , Cerámica , Tornillos Óseos , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración DentalRESUMEN
STATEMENT OF PROBLEM: Photogrammetry has been reported to be a reliable digital alternative for recording implant positions; however, the factors that may impact the accuracy of photogrammetry techniques remain unknown. PURPOSE: The purpose of this in vitro study was to assess the influence of the implant reference on the accuracy of complete arch implant scans acquired by using a photogrammetry system. MATERIAL AND METHODS: An edentulous cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was obtained and digitized by using a laboratory scanner (T710; Medit). A photogrammetry system (PIC System) was selected to obtain complete arch implant scans. An optical marker (PIC Transfer, HC MUA Metal; PIC Dental) was positioned on each implant abutment of the reference cast. Each optical marker code and position was determined in the photogrammetry software program. Three groups were created based on the implant reference selected before acquiring the photogrammetry scans: right first molar (IPR-3 group), left canine (IPR-11 group), and left first molar (IPR-14 group) (n=30). Euclidean linear and angular measurements were obtained on the digitized reference cast and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and the Tukey tests were used to analyze the trueness data. The Levene test was used to analyze the precision values (α=.05 for all tests). RESULTS: One-way ANOVA revealed significant linear (P=.003) and angular (P=.009) trueness differences among the groups tested. Additionally, the Tukey test showed that the IPR-11 and IPR-14 groups had significantly different linear (P<.001) and angular trueness (P<.001). The Levene test showed no significant precision linear (P=.197) and angular (P=.235) discrepancies among the groups tested. The IPR-3 group obtained the highest trueness (P<.001) and precision (P<.001) values among the groups tested. CONCLUSIONS: Implant reference impacted the accuracy of complete arch implant scans obtained by using the photogrammetry system tested. However, a trueness ±precision linear discrepancy of 6 ±3 µm and an angular discrepancy of 0.01 ±0.01 degrees were measured among the groups tested; therefore, the impact of the discrepancy measured should not be clinically significant.
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PURPOSE: To measure the impact of the scanning distance on the accuracy of complete-arch implant scans acquired by using a photogrammetry (PG) system. MATERIAL AND METHODS: An edentulous cast with 6 implant abutment analogs was obtained. A brand new implant scan body was positioned on each implant abutment and digitized using an extraoral scanner (T710; Medit) and the reference file was obtained. Three groups were created based on the scanning distance used to acquire complete-arch implant scans by using a PG (PIC System; PIC Dental): 20 (20 group), 30 (30 group), and 35 cm (35 group). An optical marker (PIC Transfer, HC MUA Metal; PIC Dental) was placed on each implant abutment and a total of thirty scans per group were acquired. Euclidean linear and angular measurements were obtained on the reference file was obtained and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and Tukey tests were used to analyze trueness. The Levene test was used to analyze the precision values (α = 0.05). RESULTS: Significant linear (P < .001) and angular trueness (P < .001) discrepancies were found among the groups. For linear trueness, Tukey test showed that the 20 and 30 groups (P < .001) and 30 and 35 groups were different (P < .001). For angular trueness, the Tukey test revealed that 20 and 30 groups (P = .003), 20 and 35 (P < .001), and 30 and 35 groups were different (P < .001) The Levene test showed no significant linear precision (P = .197) and angular discrepancies (P = .229) among the groups. CONCLUSIONS: The scanning distance influenced the trueness of complete-arch implant scans obtained with the PG method tested. The maximum linear trueness mean discrepancy among the groups tested was 10 µm and the maximum angular trueness mean discrepancy among the groups tested was 0.02 .
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Implantes Dentales , Boca Edéntula , Humanos , Técnica de Impresión Dental , Modelos Dentales , Diseño Asistido por Computadora , Imagenología TridimensionalRESUMEN
OBJECTIVE: The present manuscript describes a technique to virtually switch an implant scan body eliminating the need of obtaining a new intraoral implant digital scan. CLINICAL CONSIDERATIONS: Implant scan bodies assist on transferring the 3-dimensional position of the implants into the virtual definitive implant cast. However, if a different implant part is desired during the designing procedures of the implant restoration such as selecting a different implant abutment of varying height, angulation, or manufacturer, a new intraoral implant digital scan with the specific implant scan body is required. CONCLUSIONS: This novel protocol aims to reduce possible complications that require capturing a new intraoral implant digital scan, facilitate prostheses design modifications after the obtention of the definitive intraoral implant digital scan, and to ease the manufacturing procedures. CLINICAL SIGNIFICANCE: The novel technique may provide a solution for virtually switch implant scan bodies for fabricating implant-supported single crowns or short-span prostheses. Additional studies are needed before its clinical implementation.
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Diseño Asistido por Computadora , Implantes Dentales , Coronas , Técnica de Impresión Dental , Imagenología TridimensionalRESUMEN
PURPOSE: The purpose of the present clinical study was to compare the Ricketts and Steiner cephalometric analysis obtained by two experienced orthodontists and artificial intelligence (AI)-based software program and measure the orthodontist variability. MATERIALS AND METHODS: A total of 50 lateral cephalometric radiographs from 50 patients were obtained. Two groups were created depending on the operator performing the cephalometric analysis: orthodontists (Orthod group) and an AI software program (AI group). In the Orthod group, two independent experienced orthodontists performed the measurements by performing a manual identification of the cephalometric landmarks and a software program (NemoCeph; Nemotec) to calculate the measurements. In the AI group, an AI software program (CephX; ORCA Dental AI) was selected for both the automatic landmark identification and cephalometric measurements. The Ricketts and Steiner cephalometric analyses were assessed in both groups including a total of 24 measurements. The Shapiro-Wilk test showed that the data was normally distributed. The t-test was used to analyze the data (α = 0.05). RESULTS: The t-test analysis showed significant measurement discrepancies between the Orthod and AI group in seven of the 24 cephalometric parameters tested, namely the corpus length (p = 0.003), mandibular arc (p < 0.001), lower face height (p = 0.005), overjet (p = 0.019), and overbite (p = 0.022) in the Ricketts cephalometric analysis and occlusal to SN (p = 0.002) and GoGn-SN (p < 0.001) in the Steiner cephalometric analysis. The intraclass correlation coefficient (ICC) between both orthodontists of the Orthod group for each cephalometric measurement was calculated. CONCLUSIONS: Significant discrepancies were found in seven of the 24 cephalometric measurements tested between the orthodontists and the AI-based program assessed. The intra-operator reliability analysis showed reproducible measurements between both orthodontists, except for the corpus length measurement. CLINICAL SIGNIFICANCE: The artificial intelligence software program tested has the potential to automatically obtain cephalometric analysis using lateral cephalometric radiographs; however, additional studies are needed to further evaluate the accuracy of this AI-based system.
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Inteligencia Artificial , Ortodoncistas , Humanos , Reproducibilidad de los Resultados , CefalometríaRESUMEN
Rehabilitation with dental implants is not always possible due to the lack of bone quality or quantity, in many cases due to bone atrophy or the morbidity of regenerative treatments. We find ourselves in situations of performing dental prostheses with cantilevers in order to rehabilitate our patients, thus simplifying the treatment. The aim of this study was to analyze the mechanical behavior of four types of fixed partial dentures with posterior cantilevers on two dental implants (convergent collar and transmucosal internal connection) through an in vitro study (compressive loading and cyclic loading). This study comprised four groups (n = 76): in Group 1, the prosthesis was screwed directly to the implant platform (DS; n = 19); in Group 2, the prosthesis was screwed to the telescopic interface on the implant head (INS; n = 19); in Group 3, the prosthesis was cemented to the telescopic abutment (INC; n = 19); and in Group 4, the prosthesis was cemented to the abutment (DC; n = 19). The sets were subjected to a cyclic loading test (80 N load for 240,000 cycles) and compressive loading test (100 KN load at a displacement rate of 0.5 mm/min), applying the load until failure occurred to any of the components at the abutment-prosthesis-implant interface. Subsequently, an optical microscopy analysis was performed to obtain more data on what had occurred in each group. Results: Group 1 (direct screw-retained prosthesis, DS) obtained the highest mean strength value of 663.5 ± 196.0 N. The other three groups were very homogeneous: 428.4 ± 63.1 N for Group 2 (INS), 486.7 ± 67.8 N for Group 3 (INC), and 458.9 ± 38.9 N for Group 4 (DC). The mean strength was significantly dependent on the type of connection (p < 0.001), and this difference was similar for all of the test conditions (cyclic and compressive loading) (p = 0.689). Implant-borne prostheses with convergent collars and transmucosal internal connections with posterior cantilevers screwed directly to the implant connection are a good solution in cases where implant placement cannot avoid extensions.
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STATEMENT OF PROBLEM: Occlusal collisions of articulated intraoral digital scans can be corrected by intraoral scanners (IOSs) or dental design software programs. However, the influence of these corrections on the accuracy of maxillomandibular relationship is unclear. PURPOSE: The purpose of this clinical investigation was to measure the effect of occlusal collision corrections completed by the IOSs or dental design software programs on the trueness and precision of maxillomandibular relationship. MATERIAL AND METHODS: Casts of a participant mounted on an articulator were digitized (T710). The experimental scans were obtained by using 2 IOSs: TRIOS4 and i700. The intraoral digital scans of the maxillary and mandibular arches were obtained and duplicated 15 times. For each duplicated pair of scans, a bilateral virtual occlusal record was acquired. Articulated specimens were duplicated and assigned into 2 groups: IOS-not corrected and IOS corrected (n=15). In the IOS-not corrected groups, the IOS software program postprocessed the scans maintaining the occlusal collisions, while in the IOS-corrected groups, the IOS software program eliminated the occlusal collisions. All articulated specimens were imported into a computer-aided design (CAD) program (DentalCAD). Three subgroups were developed based on the CAD correction: CAD-no change, trimming, or opening the vertical dimension. Thirty-six interlandmark distances were measured on the reference and each experimental scan to compute discrepancies by using a software program (Geomagic Wrap). Root mean square (RMS) was selected to compute the cast modifications performed in the trimming subgroups. Trueness was examined using 2-way ANOVA and pairwise comparison Tukey tests (α=.05). Precision was evaluated with the Levene test (α=.05). RESULTS: The IOS (P<.001), the program (P<.001), and their interaction (P<.001) impacted the trueness of the maxillomandibular relationship. The i700 obtained higher trueness than the TRIOS4 (P<.001). The IOS-not corrected-CAD-no-changes and IOS-not-corrected-trimming subgroups obtained the lowest trueness (P<.001), while the IOS-corrected-CAD-no-changes, IOS-corrected-trimming, and IOS-corrected-opening subgroups showed the highest trueness (P<.001). No significant differences in precision were found (P<.001). Furthermore, significant RMS differences were found (P<.001), with a significant interaction between Group×Subgroup (P<.001). The IOS-not corrected-trimmed subgroups obtained a significantly higher RMS error discrepancy than IOS-corrected-trimmed subgroups (P<.001). The Levene test showed a significant discrepancy in the RMS precision among IOSs across subgroups (P<.001). CONCLUSIONS: The trueness of the maxillomandibular relationship was influenced by the scanner and program used to correct occlusal collisions. Better trueness was obtained when the occlusal collisions were adjusted by the IOS program compared with the CAD program. Precision was not significantly influenced by the occlusal collision correction method. CAD corrections did not improve the results of the IOS software. Additionally, the trimming option caused volumetric changes on the occlusal surfaces of intraoral scans.
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STATEMENT OF PROBLEM: Intraoral scanners (IOSs) have been used in dentistry for diagnostic and treatment purposes; however, the influence of environmental factors such as humidity or temperature on the accuracy of intraoral scanning is uncertain. PURPOSE: The purpose of this in vitro study was to evaluate the influence of relative humidity and ambient temperature on the accuracy, scanning time, and number of photograms of dentate complete arch intraoral digital scans. MATERIAL AND METHODS: A completely dentate mandibular typodont was digitized by using a dental laboratory scanner. Four calibrated spheres were attached following the International Organization for Standardization (ISO) standard 20 896. A watertight box was designed to simulate 4 different relative humidity conditions (50%, 70%, 80%, and 90%) (n = 30). An IOS (TRIOS 3) was used to obtain a total of 120 complete arch digital scans (n = 120). Scanning time and number of photograms of each specimen were recorded. All the scans were exported and compared with the master cast by using a reverse engineering software program. The linear distances among the reference spheres were used to calculate trueness and precision. A unifactorial analysis of variance (ANOVA) and Levene tests followed by the post hoc Bonferroni test were used to analyze trueness and precision data, respectively. A unifactorial ANOVA followed by a post hoc Bonferroni test was also conducted to analyze scanning time and the number of photogram data. RESULTS: Statistically significant differences were found in trueness, precision, number of photograms, and scanning time (P<.05). Regarding trueness and precision, significant differences were found between the 50% and 70% relative humidity groups and the 80% and 90% relative humidity groups (P<.01). Regarding scanning time and number of photograms, significant differences were obtained among all groups, except between the 80% and 90% relative humidity groups (P<.01). CONCLUSIONS: The relative humidity conditions tested influenced accuracy, scanning time, and number of photograms in complete arch intraoral digital scans. High relative humidity conditions resulted in the decreased scanning accuracy, longer scanning time, and greater number of photograms of complete arch intraoral digital scans.
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STATEMENT OF PROBLEM: Print orientation may affect the manufacturing accuracy of vat-polymerized diagnostic casts. However, its influence should be analyzed based on the manufacturing trinomial (technology, printer, and material) and printing protocol used to manufacture the casts. PURPOSE: The purpose of this in vitro study was to measure the influence of different print orientations on the manufacturing accuracy of vat-polymerized polymer diagnostic casts. MATERIAL AND METHODS: A standard tessellation language (STL) reference file containing a maxillary virtual cast was used to manufacture all specimens using a vat-polymerization daylight polymer printer (Photon mono SE. LCD 2K) and a model resin (Phrozen Aqua Gray 4K). All specimens were manufactured using the same printing parameters, except for print orientation. Five groups were created depending on the print orientation: 0, 22.5, 45, 67.5, and 90 degrees (n=10). Each specimen was digitized using a desktop scanner. The discrepancy between the reference file and each of the digitized printed casts was measured using the Euclidean measurements and root mean square (RMS) error (Geomagic Wrap v.2017). Independent (unpaired) sample t tests and multiple pairwise comparisons using the Bonferroni test were used to analyze the trueness of the Euclidean distances and RMS data. Precision was assessed using the Levene test (α=.05). RESULTS: In terms of Euclidean measurements, significant differences in trueness and precision values were found among the groups tested (P<.001). The 22.5- and 45-degree groups resulted in the best trueness values, and the 67.5-degree group had the lowest trueness value. The 0- and 90-degree groups led to the best precision values, while the 22.5-, 45-, and 67.5-degree groups showed the lowest precision values. Analyzing the RMS error calculations, significant differences in trueness and precision values were found among the groups tested (P<.001). The 22.5-degree group had the best trueness value, and the 90-degree group resulted in the lowest trueness value among the groups. The 67.5-degree group led to the best precision value, and the 90-degree group to the lowest precision value among the groups. CONCLUSIONS: Print orientation influenced the accuracy of diagnostic casts fabricated by using the selected printer and material. However, all specimens had clinically acceptable manufacturing accuracy ranging between 92 µm and 131 µm.
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INTRODUCTION: To assess the accuracy, repeatability and reproducibility of a measurement digital technique to quantify the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment with the previous measurement traditional technique (scanning electronic microscope (SEM)). METHODS: A total of 100 fixed multibracket appliances were cemented during the 15 months orthodontic treatment and subsequently removed. The fixed multibracket appliances were submitted preoperatively and postoperatively to a micro-computed tomography (micro-CT) scan to obtain accurate standard tessellation language (STL) digital files of the fixed multibracket appliances and to a preoperatively and postoperatively SEM analysis. Afterwards, pre-operatively and postoperatively STL digital files of each fixed multibracket appliances were aligned using morphometric software with the best fit algorithm. Subsequently, area and volume wear of fixed multibracket appliances was identified, isolated and measured. RESULTS: The repeatability and reproducibility of the digital measurement method for the area (mm2) and volume (mm3) were analyzed by Gage R&R statistical analysis. The area wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 3.7% and a reproducibility of 0%. The volume of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment showed a repeatability of 0.9% and a reproducibility of 5.6%. However, the traditional measurement technique showed a repeatability of 0.58% and a reproducibility of 33.01%; hence, it was repeatable but not reproducible. CONCLUSIONS: The digital measurement technique is a reproducible, repeatable, and accurate method for quantifying the wear of the bracket slot walls of the fixed multibracket appliance after orthodontic treatment.
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Soportes Ortodóncicos , Humanos , Reproducibilidad de los Resultados , Microtomografía por Rayos X , Aparatos Ortodóncicos Fijos , Proyectos de Investigación , Diseño de Aparato OrtodóncicoRESUMEN
PURPOSE: To measure the influence of best-fit (BF) algorithms (entire dataset, 3 or 6 points landmark-based, or section-based BF) on virtual casts and their alignment discrepancies. MATERIAL AND METHODS: A mandibular typodont was obtained and digitized by using an industrial scanner (GOM Atos Q 3D 12M). A control mesh was acquired. The typodont was digitized by using an intraoral scanner (TRIOS 4). Based on the alignment procedures, four groups were created: BF of the entire dataset (BF group), landmark-based BF using 3 reference points (LBF-3 group), or 6 reference points (LBF-6 group), and section-based BF (SBF group). The root mean square (RMS) error was calculated. One-way ANOVA and post hoc pairwise multi-comparison Tukey were used to analyze the data (α = 0.05). RESULTS: Significant RMS error mean value differences were found across the groups (p < 0.001). Tukey test revealed significant RMS error mean value differences between the BF and LBF-3 groups (p = 0.022), BF and LBF-6 groups (p < 0.001), LB-3 and LB-6 groups (p < 0.001), LBF-3 and SBF groups (p < 0.001), and LBF-6 and SBF groups (p < 0.001). The LBF-6 group had the lowest trueness, while SBF and BF groups obtained the highest trueness values. Furthermore, significant SD differences were revealed across the groups tested (p < 0.001). Tukey test revealed significant SD differences between the BF and LBF-6 groups (p < 0.001), LBF-3 and LB-6 groups (p < 0.001), LBF-3 and SBF groups (p = 0.004), and LBF-6 and SBF groups (p < 0.001). The BF and SBF groups showed equal and highest precision, while the LBF-6 group had the lowest precision. CONCLUSIONS: The best-fit algorithms tested influenced the virtual casts' alignment discrepancy. Entire dataset or section-based best-fit algorithms obtained the highest virtual casts' alignment trueness and precision compared with the landmark-based method.
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Diseño Asistido por Computadora , Técnica de Impresión Dental , Modelos Dentales , Algoritmos , Análisis de Varianza , Imagenología TridimensionalRESUMEN
PURPOSE: To assess the influence of the number of teeth (2, 3, or 4) and location (molars, molar and premolar, or premolars and canines) of the bilateral virtual occlusal record on the accuracy of the virtual maxillo-mandibular relationship acquired by an intraoral scanner (IOS). MATERIAL AND METHODS: Diagnostic casts mounted on a semi-adjustable articulator were obtained. Four markers were adhered on the facial surfaces of the first molars and canines. The mounted casts were digitized using an extraoral scanner. Maxillary and mandibular intraoral digital scans were obtained using an intraoral scanner (TRIOS 4). The maxillary and mandibular digital scans were duplicated 105 times and divided into 7 groups based on the number of teeth (2, 3, or 4) and location (molar, molar and premolar, or premolars and canines) of the bilateral virtual occlusal records (n = 15). The alignment of the scans was automatically performed after the acquisition of the corresponding occlusal records by the IOS program. Eight linear distances between the gauge balls were computed on the reference scan and on the 105 digital scans. The distances obtained on the reference scan were used to calculate the discrepancies with the distances obtained on each experimental scan. The Shapiro-Wilk test showed that the data was normally distributed. The trueness and precision data were analyzed using 2-way ANOVA followed by pairwise comparison Tukey tests (α = 0.05). RESULTS: Two-way ANOVA showed that the number of teeth (p < 0.001) and the position of the virtual occlusal record (p < 0.001) were significant factors on the accuracy of the maxillo-mandibular relationship. Tukey test showed significant overall mean differences between the different groups tested: the 4-teeth group obtained the highest trueness, and the 2-teeth group showed the lowest trueness values (p < 0.001). Tukey test showed significant trueness differences between the virtual occlusal record locations. The 2-teeth record located more posteriorly obtained the lowest trueness. Significant differences in precision values were found among the subgroups tested (p < 0.001). The 2-teeth group obtained significantly more precision values than the 3- and 4-teeth groups. Additionally, there was a significant difference in precision values between the subgroup tested in which the first molar and second premolar location had the highest precision, while the first and second premolar's location obtained the lowest precision. CONCLUSIONS: The number of teeth and the location of the bilateral virtual occlusal record influenced the accuracy of the virtual maxillo-mandibular relationship obtained by the intraoral scanner tested. The more teeth included in the bilateral virtual occlusal record, the higher the accuracy of the maxillo-mandibular relationship. Additionally, the more anteriorly located the virtual bilateral occlusal record involving 2 or 3 teeth was, the higher the accuracy mean value.
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Imagenología Tridimensional , Modelos Dentales , Técnica de Impresión Dental , Diente Premolar/diagnóstico por imagen , Maxilar/diagnóstico por imagen , Diseño Asistido por ComputadoraRESUMEN
The aim of this work was to analyze and compare the removal capability, conical internal hex implant-abutment connection damage and thermal effect using ultrasonic and drilling techniques for the extraction of fractured abutment screws. Twenty abutment screws were randomly fractured into twenty dental implants and randomly extracted using the following removal techniques: Group A: drilling technique without irrigation (n = 10) (DT) and Group B: ultrasonic technique without irrigation (n = 10) (UT). The dental implants were submitted to a preoperative and postoperative micro-computed tomography (micro-CT) scan to obtain a Standard Tessellation Language (STL) digital file that determined the wear comparison by morphometry. Moreover, the thermographic effects generated by the DT and UT removal techniques were registered using a thermographic digital camera. Comparative analysis was performed by comparing the volumetric differences (mm3) between preoperative and postoperative micro-CT scans and thermographic results (°C) using the Student t test. The DT extracted 8/10 and the US 9/10 abutment screws. The pairwise comparison revealed statistically significant differences between the volumetric differences of postoperative and preoperative micro-CT scans of the DT (- 0.09 ± - 0.02mm3) and UT (- 0.93 ± - 0.32mm3) study groups (p = 0.0042); in addition, the pairwise comparison revealed statistically significant differences between the thermographic values of the DT (38.12 ± - 10.82 °C) and UT (78.52 ± 5.43 °C) study groups (p < 0.001). The drilling technique without irrigation provides a less removal capability, less conical internal hex implant-abutment connection damage and less thermal effect than ultrasonic technique for the extraction of fractured abutment screws; however, the ultrasonic technique resulted more effective for the extraction of fractured abutment screws.
Asunto(s)
Pilares Dentales , Implantes Dentales , Humanos , Análisis del Estrés Dental/métodos , Ultrasonido , Microtomografía por Rayos X , Torque , Tornillos ÓseosRESUMEN
The present study seeks to describe a novel digital measurement technique for analyzing the wear volume of controlled memory (CM)-wire NiTi alloy endodontic reciprocating files after clinical use. MATERIAL AND METHODS: Ten CM-wire NiTi endodontic reciprocating files were randomly used in ten first upper molar teeth within four root canals. The CM-wire NiTi alloy endodontic reciprocating files were subjected to preoperative and postoperative micro-computed tomography (micro-CT) scans to obtain accurate digital imaging and communication on medicine (DICOM) digital files, which were segmented using intensity-based thresholding and an exclusive OR (XOR) logical operation (Boolean algebra logical operator) to obtain a mask of the location to localize and quantify the wear volume of the CM-wire NiTi alloy endodontic reciprocating files. Gage repeatability and reproducibility statistical analysis was applied to assess the reproducibility and repeatability of this measurement technique. RESULTS: The analysis showed a repeatability and reproducibility of 0.00% for the digital measurement technique used to analyze the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use. Wear was mostly identified at the tip and cutting edges of the CM-wire NiTi alloy endodontic reciprocating files. CONCLUSIONS: This novel digital measurement technique is a repeatable, reproducible, and accurate method of quantifying the wear volume of CM-wire NiTi alloy endodontic reciprocating files after clinical use.
Asunto(s)
Aleaciones , Preparación del Conducto Radicular , Diseño de Equipo , Reproducibilidad de los Resultados , Titanio , Microtomografía por Rayos XRESUMEN
The aim of this comparative study is to analyze the influence of drilling technique on the radiographic, thermographic, and geomorphometric effects of dental implant drills and osteotomy site preparations. One hundred and twenty osteotomy site preparations were performed on sixty epoxy resin samples using three unused dental implant drill systems and four drilling techniques performed with a random distribution into the following study groups: Group A: drilling technique performed at 800 rpm with irrigation (n = 30); Group B: drilling technique performed at 45 rpm without irrigation (n = 30); Group C: drilling technique performed at 45 rpm with irrigation (n = 30); and Group D: drilling technique performed at 800 rpm without irrigation (n = 30). The osteotomy site preparation morphologies performed by the 4.1 mm diameter dental implant drills from each study group were analyzed and compared using a cone beam computed tomography (CBCT) scan. The termographic effects generated by the 4.1 mm diameter dental implant drills from each study group were registered using a termographic digital camera and the unused and 4.1 mm diameter dental implant drills that were used 30 times from each study group were exposed to a micro computed tomography (micro-CT) analysis to obtain a Standard Tessellation Language (STL) digital files that determined the wear comparison by geomorphometry. Statistically significant differences were observed between the thermographic and radiographic results of the study groups (p < 0.001). The effect of cooling significatively reduced the heat generation during osteotomy site preparation during high-speed drilling; furthermore, osteotomy site preparation was not affected by the wear of the dental implant drills after 30 uses, regardless of the drilling technique.
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The aim of this study was to construct a novel, repeatable, reproducible, and accurate measurement protocol for the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere fixed multibracket appliances. A total of 30 brackets were cemented and removed with over 30 extracted teeth embedded into three experimental models of epoxy resin. The models were scanned before and after bracket placement, bracket debonding, and polishing the remaining cement. The brackets were submitted to micro-computed tomography. The standard tessellation language digital files were aligned, segmented, and re-aligned using geomorphometric software. The digital measurement technique accuracy, repeatability, and reproducibility were analyzed using Gage R&R statistical analysis. The variability attributable to the area and volume measurement techniques of the total variability of the samples was 0.70% and 0.11% for repeatability, respectively, and 0.79% and 0.01% for reproducibility, respectively. The re-alignment procedure is a repeatable, reproducible, and accurate technique that can be used to measure the area and volume of the remaining cement after removal of fixed multibracket appliances, the area and volume of remaining cement after cement removal, the area and volume of enamel removed after cement removal, and the volume of cement used to adhere the fixed multibracket appliance.
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OBJECTIVE: Measuring soft tissue thickness after mucogingival surgery has traditionally been performed by means of a calibrated transgingival probe. The main aim of this study was to apply a non-invasive technique based on digital images formatted as Standard Tessellation Language (STL) files to quantify soft tissue volume after connective tissue grafting. CLINICAL INNOVATION REPORT: Ten patients who presented Cairo Class I gingival recession were selected for connective tissue grafting using the tunnel technique. In all patients, the initial position of the gingiva and quantity of keratinized tissue were recorded, and gingival recession was scanned with an intra-oral scanner. Six months after surgery, the same intra-oral parameters were recorded and compared with the initial registers using digital volumetric analysis software. RESULTS: Complete root coverage was obtained in most patients (90%), mean coverage being of 2.70 mm with a mean increase in volume of 115.49 mm3 in the treated areas. No pattern was identified that indicated a statistically significant relation between gingival recession and coverage volume in mm3 . CONCLUSIONS: Digital processing of pre- and post-treatment images makes it possible to measure the volume of tissue gained after tissue graft surgery simply and non-invasively. The technique is an objective and reproducible method for measuring soft tissue thickness.