Minimally invasive prosthodontic correction of pseudo class III malocclusion by implementing a systematic digital workflow: A clinical report

Fully digital workflow of an occlusal device including digital facebow record: A clinical report

In many current digital workflows for the production of occlusal devices and dentures, the traditional facebow record for the individual determination of the hinge axis has been omitted. A novel digital facebow record procedure including a scannable occlusal fork is described as a straightforward to use, cost-effective, and less time-consuming alternative to close this gap in fully digital prosthetic workflows.

Accuracy of computer-aided design trial restorations fabricated with different digital workflows

STATEMENT OF PROBLEM

Trial restorations are a versatile tool for visualizing the esthetic treatment plan and should be an accurate replica of the planned smile design. The accuracy of conventionally fabricated trial restorations has been investigated; however, studies on the accuracy of different digital workflows for trial restoration fabrication are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the accuracy of computer-aided design (CAD) trial restorations fabricated with different digital workflows.

MATERIAL AND METHODS

A patient in need of additive esthetic treatment was examined, and intraoral and extraoral photographs and intraoral digital scans were made, followed by 3D digital smile design using the exocad software program. The reference virtual design was converted into trial restorations (N=40) by using different digital workflows: subtractive manufacturing, additive manufacturing, additive manufacturing of 3D designed index, and silicone index on an additively manufactured cast. Fabricated trial restorations of all groups were scanned with a desktop scanner, providing a standard tessellation language (STL) file serving as the test data for each trial restoration. All the STL files of the test and reference data were imported into a reverse engineering software program to evaluate the 3D trueness of each workflow. Also, analog and digital 2D linear measurements (maxillary left central incisor height, maxillary left central incisor width, and intercanine width) were made to assess any dimensional alterations between the fabricated trial restorations and the reference digital smile design. A 1-way analysis of variance (ANOVA) was used to analyze the data followed by the Tukey post hoc test (α=.05).

RESULTS

For 3D trueness measurements, root mean square (RMS) values representing the deviations between the fabricated trial restorations and the reference digital smile design varied significantly among the different groups (P<.001), with the highest mean deviation found in the group of additive manufacturing of 3D designed index (0.21 ±0.01 mm), while the lowest mean value of deviation was found in the group of subtractive manufacturing (0.11 ±0.02 mm). For both the digital and analog 2D linear measurements, post hoc pairwise comparisons showed the group of additive manufacturing of 3D designed index to have significantly higher values of deviation than the other groups in all assigned measurements (P<.001).

CONCLUSIONS

The accuracy of CAD trial restorations was affected by the fabrication technique, and implementing conventional steps in the digital workflows of trial restoration fabrication may result in discrepancies that affect accuracy when compared with the reference design.

Effect of Restorative Material on Mechanical Response of Provisional Endocrowns: A 3D-FEA Study

The goal of this study was to evaluate the stress distribution in an endocrown restoration according to different provisional restorative materials. An endodontically treated maxillary molar model was selected for conducting the finite element analysis (FEA), with a determined amount of dental remnant of 1.5 mm. The model was imported to the analysis software (ANSYS 19.2, ANSYS Inc., Houston, TX, USA) in STEP format. All contacts were considered perfectly bonded. The mechanical properties of each structure were considered isotropic, linear, elastic, and homogeneous. Three different provisional restorative materials were simulated (acrylic resin, bis-acrylic resin, and resin composite). An axial load (300 N) was applied at the occlusal surface in the center of the restoration. Results were determined by colorimetric stress maps of maximum principal stress, maximum shear stress, and total deformation. The different materials influenced the stress distribution for all structures; the higher the material’s elastic modulus, the lower the stress magnitude on the cement layer. In the present study, all provisional restorative materials showed similar stress patterns in the endocrown and on the cement layer however, with different magnitude. Based on this study limitation, the use of resin composite to manufacture provisional endocrowns is suggested as a promising material to reduce the stresses in the cement layer and in the dental tissue surfaces.

Dental software classification and dento-facial interdisciplinary planning platform

OBJECTIVE

Despite all advantages provided by the digital workflow, its application in clinical practice is still more focused on device manufacturing and clinical execution than on treatment planning and communication. The most challenging phases of treatment, comprehensive planning, diagnosis, risk assessment, and decision-making, are still performed without significant assistance from digital technologies. This article proposes a new dental software classification based on the digital workflow timeline, considering the moment of patient's case acceptance as key in this classification, and presents the ideal software tools for each phase.

CLINICAL CONSIDERATIONS

The proposed classification will help clinicians and dental laboratories to choose the most appropriate software during the treatment planning phase and integrate virtual plans with other software platforms for digitally guided execution. A dento-facial interdisciplinary planning platform virtually simulates interdisciplinary clinical procedures and assists in the decision-making process.

CONCLUSIONS

The suggested classification assists professionals in different phases of the digital workflow and provides guidelines for improvement and development of digital technologies before treatment plan acceptance by the patient.

CLINICAL SIGNIFICANCE

Three-dimensional interdisciplinary simulations allow clinicians to visualize how each dental procedure influences further treatments. With this treatment planning approach, predictability of different procedures in restorative dentistry, orthodontics, implant dentistry, periodontal, and oral maxillofacial surgery is improved.