International Journal of Computerized Dentistry最新文献

Aim: The objective of the present article is to demonstrate the digital workflow used to manufacture an adjusted oral splint in a patient case.

Materials and methods: A 25-year-old female patient presented for management of her bruxism. Therefore, an adjusted oral splint was manufactured. A computer-aided motion analysis of the patient was conducted (JMA Optic). Full-arch scans of the maxilla and mandible, a biocopy of the maxilla with a bite fork, and buccal scans of the centric jaw relation (Primescan) were performed. The jaw relation was determined beforehand by ballistic closing on a chairside-fabricated anterior jig. The digital construction of a Michigan splint took place in the dental laboratory. The design was nested and milled from a polymethyl methacrylate (PMMA)-containing blank (CLEARsplint Disc).

Results: The oral splint was inserted into the patient's mouth and checked to ensure a tension-free fit. The static and dynamic contact relationship was checked. During the follow-up visit, the patient reported an improvement in tension in the masticatory muscles.

Conclusion: The described procedure allows for the manufacture of an adjusted oral splint through a purely digital workflow.

Aim: New technologies such as tactile robots and artificial intelligence (AI) are finding their way into clinical practice in dentistry and could contribute to the improvement of oral health care in the future. The hypothesis of the present in vitro pilot study trial was that a collaborative tactile robot programmed by a dental student could remove interproximal artificial plaque as effectively as a human operator.

Materials and methods: Model teeth were fully covered with artificial plaque and set into phantom jaws. First, a robot was programmed by a dental student to perform interproximal cleaning with an interproximal brush. Second, the teeth were covered with artificial plaque again, and the dental student performed the interproximal cleaning manually. Both experiments were repeated five times. Residual plaque was measured with binary pictures. Surface coverage was reported, and the comparison of methods was performed with significance defined at α = 0.05.

Results: No statistically significant difference was found in the cleaning result between the robot and the human operator.

Conclusion: The results of the present in vitro pilot study indicate that a tactile robot with integrated AI programmed by a dental student can perform interproximal cleaning as effectively as a dental student.

Practical implications: In the future, the use of robot assistants to support oral hygiene, eg, in patients with reduced motor skills or impaired vision, should be fur ther investigated.

Aim: The aim of the present in vitro study was to investigate the effects of different sintering procedures on the fit, color parameters, and fracture load of monolithic fixed partial prostheses (FPPs).

Materials and methods: A metal master model was scanned and FPPs were designed. Groups were created by fabricating FPPs using four different sintering procedures (n = 10): Prettau-Standard (PST); Prettau-Slow (PSL); Ice-Speed (ISP); Ice-Standard (IST). PST-PSL (Group P; N = 20) and ISP-IST (Group I; N = 20) were colored with different coloring liquids. The marginal and internal fit were measured using the silicone replica method. CIELAB values of the samples were measured using a spectrophotometer. Then, for each sample, the die was obtained from polymethyl methacrylate. The specimens were cemented into dies and tested in a universal testing machine for fracture load. One-way ANOVA was performed to assess the effect of the sintering procedure on the marginal and internal fit; fracture load; and ∆E00, ∆L', ∆C', and ∆H' values of the FPPs.

Results: The PSL and PST groups showed significantly smaller internal and marginal fit values compared with the ISP group. Additionally, the internal fit values of the IST group were significantly higher than those of Group P. Sintering time reduction led to a decrease in ∆E00 values. Fracture load values were not statistically significantly affected by the different sintering procedures for both brands.

Conclusion: Different sintering procedures did not have a clinically significant effect on fit and fracture load. Different sintering procedures were found to have an impact on the color change of monolithic zirconia restorations.

Aim: The aim of the present study was to evaluate the segmentation accuracy of the dentition by testing four open-source semi-automatic software programs.

Materials and methods: Twenty CBCT scans were selected to perform semi-automatic segmentation of the maxillary and mandibular dentition. The software programs tested were InVesalius, ITK-SNAP, 3D Slicer, and Seg3D. In addition, each tooth model was manually segmented using Mimics software; this was set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the tooth models obtained with the semi-automatic software and the GS model as well as to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated, calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the tooth models compared with the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analyzed to perform comparisons between the investigated software programs.

Results: Statistically significant differences were found in the volumetric and matching percentage data (P 0.05). InVesalius was the most accurate software program for 3D rendering of the dentition, with a volumetric bias (Mimics software) ranging from 4.59 to 85.79 mm3, while ITK-SNAP showed the highest volumetric bias, ranging from 30.22 to 319.83 mm3. The mismatched area was mainly located at the radicular tooth region. The volumetric data showed excellent inter-software reliability, with coefficient values ranging from 0.951 to 0.997.

Conclusion: Different semi-automatic software algorithms could generate different patterns of inaccuracy error in the segmentation of teeth.

Objective: To investigate the application of dynamic navigation guidance technology in different implantation scenarios, and to provide a scientific basis for the innovation and advancement of implantation techniques.

Methods: Fifteen cases of patients with malocclusions admitted between January 2021 and February 2023 were selected as the study subjects. All patients underwent dynamic navigation-guided oral implantation interventions. CBCT scans were taken after implantation surgery to record deviations of implantation points, including implantation point deviation, endpoint deviation, and angle deviation.

Results: Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. CBCT effectively evaluated the state of the patient's periodontal implant, analyzed the state of the patient's lesion area, and improved the quality of implant intervention through CBCT guidance. The implantation point deviation was (0.407±0.193) mm, the endpoint deviation was (0.492±0.201) mm, and the implant angle deviation was (2.162±0.283)°. There was no significant difference in implantation point deviation in the anterior and posterior parts of the upper and lower jaws after intervention (P>0.05). However, there were significant differences in endpoint deviation and implant angle deviation among the anterior and posterior parts of the upper and lower jaws (P<0.05).

Conclusion: Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. However, there is relatively greater endpoint deviation and implant angle deviation in the posterior part of the upper jaw.

Aim: The present study aimed to evaluate the intaglio surface trueness and fit of zirconia crowns depending on the different machining strategies used with the Cerec system.

Materials and methods: Thirty duplicate tooth models for a single zirconia crown were randomly assigned to three groups (n = 10) according to the machining mode used for fabrication: grinding, wet milling, and dry milling. The scan data of the final crowns were compared with their design data to evaluate the intaglio surface trueness. The marginal and internal fit were evaluated using a cross-sectional method. The time required for the machining and sintering processes was measured for each group.

Results: The wet-milling group showed better trueness (root mean square: 13.8 ± 1.0 μm) than the grinding and dry-milling groups (P < 0.001). The marginal gap was greater in the grinding group (58.6 ± 28.9 μm) than that in the wet- and dry-milling groups (P < 0.001). The dry-milling group required the shortest time for the manufacturing process.

Conclusion: All machining modes fabricated crowns with a clinically acceptable trueness and fit. However, the dry-milling mode was advantageous for the chairside CAD/CAM system with respect to time efficiency.

Aim: Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of the present in vitro study was to estimate and compare the influence of the post length and type on the fracture strength of endodontically treated maxillary central incisors.

Materials and methods: Sixty extracted human maxillary central incisors were decoronated 2 mm above the cementoenamel junction. The teeth were selected and subjected to standard endodontic treatment, resulting in three groups with different preparation lengths: 5, 7.5, and 10 mm. Each group was randomly divided into two subgroups according to the post type: zirconia or fiber. After appropriate surface treatment, they were cemented with adhesive resin cement and restored with zirconia crowns. Thermocycling (5°C to 55°C, 60 s, 1500 cycles) was performed after cementing the zirconia crowns onto each tooth. Prepared samples were subjected to a compressive static load of 0.5 mm/min, at an angle of 130 degrees to the long axis of the roots, using a universal testing machine (Matest) at a crosshead speed of 0.5 mm/min, until fracture. The significance of the results was assessed using two-way analysis of variance (ANOVA) and the Tukey-Kramer test (α = 0.05).

Results: The ANOVA analysis indicated significant differences (P < 0.05) between the groups. The Tukey-Kramer test revealed no significant differences among the zirconia posts with lengths of 5 mm (26.5 N ± 13.4), 7.5 mm (25.2 N ± 13.9), and 10 mm (17.1 N ± 5.2). Also, in the fiber post group, there was no significant difference when the posts with lengths of 7.5 mm (13.4 N ± 11.0) were compared with those of 5 mm (6.9 N ± 4.6) and 10 mm (31.7 N ± 13.1). The 10-mm-long post displayed superior fracture strength, and the 5-mm-long post showed significantly lower mean values (P < 0.001).

Conclusions: The fracture strength of zirconia posts (with lengths of 5 and 7.5 mm) was found to be significantly higher than that of fiber posts (with lengths of 5 and 7.5 mm). The 10-mm-long fiber post group demonstrated significantly higher fracture strength values, and the 5-mm-long fiber post group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P < 0.001). The fracture strength analysis with a universal testing machine is the only method that enables the estimation of the differences between zirconia and fiber posts with different lengths in endodontically treated teeth.