A workflow for fabricating a hollow obturator by using 3D digital technologies

Influence of different designs of bulb support structures on the accuracy and weight of 3D printed maxillary obturators. An in vitro study

STATEMENT OF PROBLEM

Evidence is lacking on the influence of different designs of bulb support structures on the accuracy of 3-dimensional (3D) printed obturators.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of various infill designs (hollow, honeycomb, and gyroid) for the bulb of an obturator on the accuracy and weight of digital light projection (DLP) 3D printed maxillary obturators.

MATERIAL AND METHODS

A maxillary obturator was virtually designed and used to obtain 3 digital reference files which were defined based on the design of the infill support structure within the bulb: hollow, honeycomb, and gyroid. The resultant standard tessellation language (STL) files were used to fabricate the obturators using a DLP 3D-printer in FREEPRINT denture resin material (n=10 per each group design). The fitting surfaces of all printed specimens (n=30) were digitized using a laboratory scanner, and the scan STL files were exported to the Geomagic control X program for dimensional accuracy analysis (trueness and precision) using the digital subtraction technique. One-way analysis of variance (ANOVA) was used for analysis (α=.05) RESULTS: Quantitative analysis revealed no significant difference in root mean square estimate (RMSE) values among the test groups for trueness (P=.326) and precision (P=.140). Hollow bulb design was significantly lighter in weight than both honeycomb and gyroid infill designs (P<.001). Colormaps revealed increased areas of negative deviation around the circumference of the bulb wall in the hollow design compared with both the gyroid and honeycomb groups and the close surface matching of fitting surfaces in the 3 groups.

CONCLUSIONS

The lack of significant difference in accuracy among the tested groups and the significantly lighter hollow design obturator compared with honeycomb and gyroid designs favors the selection of the hollow bulb design in the digital fabrication of maxillary obturators.

Fully integrated additive manufacturing of an obturator prosthesis for an edentulous patient with a maxillectomy defect

Maxillary defects pose challenges for prosthodontists, especially when patients have no remaining teeth. This clinical report describes rehabilitation with a complete denture obturator fabricated in 2 visits for an edentulous patient after a maxillectomy. The obturator base and artificial teeth were digitally designed and merged into a 1-piece prosthesis. Following a virtual reduction, the integrated prosthesis and a gingival veneer were calculated and then printed and bonded together to complete the fabrication. Balanced occlusion was achieved with the assistance of a digital occlusion analyzer at the insertion visit. This approach avoided base-tooth assembly deviations and provided a prosthesis with good patient-reported outcomes at the 6-month follow-up.

A fully digital approach to replacing an obturator prosthesis using a 3D printed closed hollow bulb: Α dental technique

The replacement of an obturator prosthesis using conventional methods has multiple issues. Standard tessellation language files generated from the superimposition of an accurate intraoral scanning of the maxillary defect and direct data acquisition of the existing hollow bulb obturator can facilitate the precise design of the prosthesis, requiring only minor adjustments. Rapid prototyping manufacturing techniques seem to ensure precise control of the integrity of the prosthetic component completion. The success of the technique is the simplicity and repeatability of designing and fabricating a retrievable and easily repairable obturator.

An integrated hollow bulb obturator prosthesis with a metal framework for a soft palate defect fabricated by multiple digital techniques

The digital workflow to fabricate an integrated hollow bulb obturator prosthesis with a metal framework for a patient with soft palate defect is described. The framework was digitally designed with an open lattice denture base connector to facilitate the assembly of the hollow bulb obturator and printed with titanium. A functional impression of the palatopharyngeal area was made, and an integrated 3-dimensional (3D) cast was obtained by aligning the data of the functional impression to the preliminary intraoral scan data. The hollow bulb obturator and a palatal cover were designed based on the integrated 3D cast and the framework design data and printed with light-polymerizing denture base resin. The printed framework, obturator, and palatal cover were assembled and bonded without a physical cast, and the definitive prosthesis exhibited good fit, retention, and stability.

Comparison of the weight of conventionally heat-processed hollow and solid obturators and 3D printed hollow obturators

STATEMENT OF PROBLEM

The weight of larger obturators places increased stress on the supportive teeth and bearing tissue and allows gravity to act as a dislodging factor affecting the stability and retention of the prosthesis. However, whether conventionally processed and 3-dimensionally (3D) printed hollow obturators have similar reduced weights compared with solid obturators is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the weight difference between conventionally heat-processed complete denture obturators with and without hollowing and 3D printed obturators with a hollow bulb.

MATERIAL AND METHODS

Obturators were fabricated as conventionally heat-processed solid obturators, conventionally heat-processed with a hollow obturator bulb, and 3D printed with a hollow obturator bulb. Nine obturator prostheses were fabricated for each type of Aramany Class I, Class II, and Class III defect. The weights of each of the 27 obturator prostheses were measured, and a statistical analysis was performed with exact versions of the Kruskal-Wallis test or Wilcoxon Rank Sum test (α=.05).

RESULTS

Conventionally heat-processed solid obturators were significantly heavier than the conventionally heat-processed hollow (P<.001) or the 3D printed hollow obturators (P<.001). No significant difference (P=.222) was found between the conventionally heat-processed hollow and 3D printed hollow obturators. The decrease in weight was proportional to the size of the defect with the Aramany Class I defect having the largest differences in weight between the different fabrication methods, followed by Class II, and then Class III with a much smaller defect.

CONCLUSIONS

Additive manufacturing could be a suitable alternative to conventional techniques for the fabrication of a closed hollow obturator because of the comparable weights.

Three-piece digital complete denture obturator with a heptagonal key assembly for a patient with a total maxillectomy: A dental technique

Digital workflows have been used in the oral rehabilitation of patients with maxillofacial defects. However, dental techniques for fabricating a denture obturator for patients with a total maxillectomy are lacking. This technical report describes the use of digital technology to produce a milled complete denture obturator using an intraoral scanner, a computer-aided design software program, and computer-aided manufacturing. The limited size of the milled polymethylmethacrylate disk was resolved by separating the prosthesis into 3 pieces: the obturator base, denture base, and artificial teeth.

Combined digital-conventional workflow to fabricate a definitive obturator from an interim obturator for a patient with an anterior maxillectomy defect

An existing interim obturator can be reproduced as the definitive one using digital technology, with benefits for a patient with a maxillectomy. By digitally scanning the oral condition and the existing interim obturator, a definitive obturator, including a computer-aided designed and computer-aided manufactured metal framework, was fabricated and delivered to a patient with an anterior maxillectomy defect by following a combined digital and conventional workflow. This technique can hasten the adaptation of the patient to the new obturator and ensure a more comfortable and safer clinical procedure.

CAD-CAM Hollow Obturator Prosthesis: A Technical Report

An obturator with a hollow bulb can decrease the overall weight of the prosthesis, stress on the underlying tissues, and patient discomfort. Although many techniques and materials have been proposed in the literature for hollowing the obturator prosthesis, they are often time consuming and technique sensitive. This proposed technique used an open‐source software program to hollow a digital design of a solid obturator base from a commercially available software in one single convenient step. The hollowing process allowed precise control of prosthesis thickness at the hollow space area for desirable hermetic seal and prosthesis strength.

The Trueness of Obturator Prosthesis Base Manufactured by Conventional and 3D Printing Techniques

PURPOSE

To compare the intaglio surface trueness of obturator prosthesis bases manufactured by traditional compression molding, injection molding, and 3D printing techniques.

MATERIALS AND METHODS

A complete edentulous master cast with Aramany Class I maxillary defect was selected for this in vitro study. Four study groups (n = 10/group) were included in this study, Group A: Compression Molding, Group B: Injection Molding, and Group C: Cara Print 3D DLP Printer, and Group D: Carbon 3D DLS Printer. All obturator prostheses' intaglio surfaces were scanned with a laboratory scanner (E4; 3Shape Inc, New Providence, NJ) and the dimensional differences between study samples and their corresponding casts were calculated as the root mean square (measured in mm, absolute value) using a surface matching software (Geomagic design X; 3D Systems, Rock Hill, SC). One-way Analysis of variance (ANOVA) and Fisher's least significant difference (LSD) test were used to compare groups differences in RMS (α = 0.05).

RESULTS

There was a significant effect of manufacturing technique on the RMS values for the 4 conditions [F(3,36) = 5.743, p = 0.003]. Injection Molding (0.070 mm) and Compression Molding groups (0.076 mm) had a lower interquartile range, and the Cara Print 3D-Printer group (0.427 mm) and Carbon 3D-Printer (0.149 mm) groups had a higher interquartile range. The Injection Molding group showed the best and uniform surface matching with the most area in green in the color maps. The Injection Molding group (0.139 ± 0.049 mm) had significantly lower RMS than all other groups (p < 0.001 for all comparisons). Compression Molding (0.269 ± 0.057 mm), Cara Print 3D-Printer (0.409 ± 0.270 mm), and Carbon 3D-Printer (0.291 ± 0.082 mm) groups were not significantly different from each other (Compression Molding versus Carbon 3D-Printer, p = 0.59; Compression Molding versus Cara Print 3D-Printer, p = 0.25; Cara Print 3D-Printer versus Carbon 3D-Printer, p = 0.40).

CONCLUSION

Obturator prosthesis bases manufactured with injection molding technique showed better intaglio surface trueness than ones made by the compression molding technique and 3D printers. Although obturator prosthesis bases manufactured from different 3D printers showed similar trueness, a DLP 3D printer produced less consistent outcome than a DLS 3D printer.

Digital Workflow in Maxillofacial Prosthodontics—An Update on Defect Data Acquisition, Editing and Design Using Open-Source and Commercial Available Software

Background: A maxillofacial prosthesis, an alternative to surgery for the rehabilitation of patients with facial disabilities (congenital or acquired due to malignant disease or trauma), are meant to replace parts of the face or missing areas of bone and soft tissue and restore oral functions such as swallowing, speech and chewing, with the main goal being to improve the quality of life of the patients. The conventional procedures for maxillofacial prosthesis manufacturing involve several complex steps, are very traumatic for the patient and rely on the skills of the maxillofacial team. Computer-aided design and computer-aided manufacturing have opened a new approach to the fabrication of maxillofacial prostheses. Our review aimed to perform an update on the digital design of a maxillofacial prosthesis, emphasizing the available methods of data acquisition for the extraoral, intraoral and complex defects in the maxillofacial region and assessing the software used for data processing and part design. Methods: A search in the PubMed and Scopus databases was done using the predefined MeSH terms. Results: Partially and complete digital workflows were successfully applied for extraoral and intraoral prosthesis manufacturing. Conclusions: To date, the software and interface used to process and design maxillofacial prostheses are expensive, not typical for this purpose and accessible only to very skilled dental professionals or to computer-aided design (CAD) engineers. As the demand for a digital approach to maxillofacial rehabilitation increases, more support from the software designer or manufacturer will be necessary to create user-friendly and accessible modules similar to those used in dental laboratories.

Fabrication of a 3-dimensionally printed definitive cast for an obturator prosthesis by merging intraoral scan image with cone beam computed tomography data: A clinical report

This clinical report focuses on the production of a 3-dimensionally printed definitive cast by using digital scans to fabricate an obturator prosthesis for a completely edentulous patient with a maxillary defect. A merged intraoral scanner image of the soft tissue anatomy of maxillary structures with volumetric data of the craniofacial hard and soft tissues obtained from a cone beam computed tomography scan was used to generate a virtual cast, producing the polyurethane definitive cast manufactured by using a 3-dimensional printer.

Prosthodontic Applications of Polymethyl Methacrylate (PMMA): An Update

A wide range of polymers are commonly used for various applications in prosthodontics. Polymethyl methacrylate (PMMA) is commonly used for prosthetic dental applications, including the fabrication of artificial teeth, denture bases, dentures, obturators, orthodontic retainers, temporary or provisional crowns, and for the repair of dental prostheses. Additional dental applications of PMMA include occlusal splints, printed or milled casts, dies for treatment planning, and the embedding of tooth specimens for research purposes. The unique properties of PMMA, such as its low density, aesthetics, cost-effectiveness, ease of manipulation, and tailorable physical and mechanical properties, make it a suitable and popular biomaterial for these dental applications. To further improve the properties (thermal properties, water sorption, solubility, impact strength, flexural strength) of PMMA, several chemical modifications and mechanical reinforcement techniques using various types of fibers, nanoparticles, and nanotubes have been reported recently. The present article comprehensively reviews various aspects and properties of PMMA biomaterials, mainly for prosthodontic applications. In addition, recent updates and modifications to enhance the physical and mechanical properties of PMMA are also discussed.