Hermeticity of a hollow obturator model using CAD and rapid prototyping technologies

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.

Digital workflow feasibility for the fabrication of intraoral maxillofacial prosthetics after surgical resection: a systematic literature review

OBJECTIVES

To evaluate the current evidence of digital workflow feasibility based on the data acquisition methods and the software tools used to fabricate intraoral prostheses for patients with partial or total maxillary and mandibular defects.

MATERIALS AND METHODS

An electronic search was performed in PubMed, SCOPUS, and Web of Science using a combination of relevant keywords: digital workflow, digital designing, computer-assisted design-computer aided manufacturing, 3D printing, maxillectomy, and mandibulectomy. The Joanna Briggs Institute Critical Appraisal Tool was used to assess the quality of evidence in the studies reviewed.

RESULTS

From a total of 542 references, 33 articles were selected, including 25 on maxillary prostheses and 8 on mandibular prostheses. The use of digital workflows was limited to one or two steps of the fabrication of the prostheses, and only four studies described a complete digital workflow. The most preferred method for data acquisition was intraoral scanning with or without a cone beam computed tomography combination.

CONCLUSION

Currently, the fabrication process of maxillofacial prostheses requires combining digital and conventional methods. Simplifying the data acquisition methods and providing user-friendly and affordable software may encourage clinicians to use the digital workflow more frequently for patients requiring maxillofacial prostheses.

In vitro evaluation of shape-memory hydrogels for removable dental prostheses and optimization of phase-transition temperature for intraoral use

STATEMENT OF PROBLEM

Removable dental prostheses require periodic relining with the loss of intaglio surface fit because of mucosal shape changes over time. Therefore, a new material with high adaptability to tissue changes over time would be beneficial.

PURPOSE

This study focused on a shape-memory gel (SMG) that softens when heated, retains its shape when cooled, and returns to its original shape when reheated. The purpose was to optimize SMG for intraoral use by controlling the ratio of 2 acrylate monomers and to evaluate the changes in the shape memory and physical properties of SMG with temperature and to evaluate biocompatibility.

MATERIAL AND METHODS

SMG specimens were synthesized using the following mixing ratios of 2 monomers, docosyl acrylate (DA) and stearyl acrylate (SA): 0:100, 25:75, 50:50, 75:25, and 100:0. SMG specimens were photopolymerized using a fluorescent light-polymerizing unit. To evaluate shape memory as a function of temperature, permanent deformation was measured based on the standardized compression set test for thermoplastic rubber. For evaluation of the physical properties and cytotoxicity, a 3-dimensionally printed denture base material was used as the control material. All assessments were compared between the groups by using 1-way analysis of variance followed by the Tukey-Kramer multiple comparison test (α=.05).

RESULTS

SMGs with a higher amount of DA maintained their compressed shape at room and intraoral temperatures. However, the SMG matrices softened and recovered their original shapes above 60 °C. SMGs showed Shore A hardness equivalent to that of the denture-base polymer material at intraoral temperatures because of the high phase-transition temperature. The low water solubility of SMGs supported the biocompatibility test results.

CONCLUSIONS

SMG, in which the phase-transition temperature was controlled by mixing acrylate monomers with different melting points, exhibited shape memory in the intraoral environment. The results indicate the feasibility of applying SMG for the fabrication of removable dental prostheses because of its high adaptability to tissue changes over time and biocompatibility.

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.

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.

Rapid additive manufacturing of an obturator prosthesis with the use of an intraoral scanner: A dental technique

A protocol for a completely digital manufacturing process for an obturator prosthesis is described. An intraoral scanner was used to capture the mandible and maxilla together with the sinus defect. The obturator base and the artificial teeth were created with a computer-aided design software program and manufactured by 3-dimensional printing. Stainless steel clasps provided the retention for the prosthesis.