Implant-supported removable partial dentures with magnetic
attachments using selective laser-sintered frameworks: A
Case report
IMAIZUMI N,1,2） SUZUKI Y,1,2） NAKATA T,1,2）
SHIMPO H,1,2） KURIHARA D,1,2） OHKUBO C1,2）
１）

2）

Dept. of Removable Prosthodontics, Tsurumi University School of Dental Medicine
Center of Maxillofacial Implantology, Tsurumi University Dental Hospital

Abstract【Objective】
A removable partial denture framework can now be fabricated with Co-Cr and titanium alloys by
selective laser melting (SLM), a rapid prototyping technology. The advantages of this technology
are high precision, appropriate mechanical strength, and the ability to make complicated framework
shapes. In this case, CAD/CAM technology was used to fabricate a denture framework and bar
attachment with magnets for an implant-supported removable partial denture (IRPD).
【Method】
A bar attachment for an IRPD was milled from a pure titanium disk within the wax denture, and themagnetic attachment keeper was placed on it. After the working cast with a bar attachment and thewax denture were both scanned, the denture framework was designed by CAD. The framework wasthen fabricated by SLM with Ti-6Al-4V alloy powder.
【Results, Discussion】
A titanium milled bar attachment with magnets and a laser-sintered framework were used for theIRPD. Greater retention, as well as increased strength and accuracy, can be obtained using
magnetic attachments and CAD/CAM technology.
Introduction
In recent years, CAD/CAM technology has been successfully introduced into restorative dentistry
and maxillofacial technology. Moreover, selective laser melting (SLM) rapid prototyping
technology can be applied successfully for the fabrication of a removable partial denture alloy
framework. The advantages of this technology are high precision, appropriate mechanical strength,
and the ability to make complicated framework shapes. This case report describes the fabrication ofa denture framework and bar attachment with magnets for an implant-supported removable partialdenture (IRPD) using CAD/CAM technology.
Outline of the Case
The patient was a 67-year-old partially edentulous woman with 5 remaining teeth (#17, #23, #25,#26, and #27) in the maxillary arch and 4 missing teeth (#36, #37, #46, and #47) in the mandibulararch. Her chief complaint was an unstable existing maxillary denture. A panoramic radiographshowed severe ridge resorption in the maxillary molar regions (Figs.1, 2).
The patient was informed about the possibility of using a conventional removable partial denture,
implant-fixed prosthesis, and IRPD for the maxillary and mandibular jaws. After giving informed
consent, the patient selected an IRPD for the maxillary jaw and an implant fixed prosthesis for themandibular jaw.

Fig.1 Intraoral view before treatment:
A. Frontal view B. Maxillary occlusal view C. Mandibular occlusal viewFig.2 Pretreatment panoramic radiograph

Clinical Procedure
After CT scanning to produce 3D computer-generated images, the position and direction of implant
placement were virtually planned using 3D planning software. The simulation data of implant
placement were sent to the dental laboratory for the fabrication of the surgical template (Fig.3).

Fig.3 The simulation of implant placement for the maxillary jaw
After #17 was extracted and the surgical template was fixed in the patient’s mouth, the implants
were placed using the Guided Surgery System (Straumann Japan, Tokyo) (Fig.4). According to thesurgical guide, four implants were placed in the #17, #15, #12, and #22 regions in order tominimize the denture displacement under the bite force in the maxillary jaw (Fig.5). In themandibular jaw, four implants were placed in the #47, #46, #36, and #37 regions for implant-fixed
prosthesis (Fig.6). After implant placement, 2 remaining teeth (#26 and #27) were extracted due tosevere periodontal disease.

Fig.4 Surgical guide fixed in the mouthFig.5 Placement of four implants in the maxillary jaw

Fig.6 Postoperative panoramic radiograph
After a period of healing, implant-fixed prostheses were fabricated for the mandibular jaw using
CAD/CAM. The frameworks of implant superstructures were virtually designed and milled using
commercially pure titanium (CP Ti). After implant-fixed prostheses were completed, they wereplaced on the implant using a retaining screw (Fig.7). In the maxillary jaw, the working casts wereproduced according to the conventional impression technique. The jaw relationship was recorded,
and the artificial teeth were conventionally arranged (Fig.8).

Fig.7 Completed mandibular prosthesis

Fig.8 The artificial teeth wereconventionally arranged.

The working cast was scanned by using a laboratory scanner (D2000, 3Shape). The bar attachment
was virtually designed within the wax denture using 3D CAD software (Dental Designer, 3Shape)and milled from a CP Ti disk (Figs.9, 10). The keeper of the magnetic attachment（Physio Magnet,NEOMAX）was attached on the bar. After the working cast with a bar attachment and the wax
denture were both scanned, the denture framework was virtually designed with 3D CAD software(Dental Lab System, SensAble Technologies) (Fig.11). During the SLM process, the support wasattached on the occlusal surface of the denture framework. The framework was fabricated by SLM
with 50 µm Ti-6Al-4V alloy powder (Fig.12). After the metal framework was cut from the support,
it was finished and polished.

Fig.9 The bar was designed virtually.

Fig.10 The bar was milled from a CP Ti disk.

Fig.11 Screen captures of the virtual IRPD framework

Fig.12 The support was attached on theocclusal surface of the framework.

Fig.13 Completed denture framework
Using heat-polymerized PMMA (Acron, GC Corp.), an IRPD with a laser-sintered framework wasconventionally completed (Figs.14, 15). The magnetic assembly was connected to the denture basewith auto-polymerized resin under occlusal force. Sufficient retention was obtained with a titanium
milled bar and magnetic attachments. No clinical problems, such as detachment of the magnetic
attachment, decreased retentive forces, and denture breakage, were observed.

Fig.14 Trial placement of the bar with keepers of the magnetic attachment

AFig.15 Completed maxillary IRPD: A. Frontal view B. Maxillary occlusal view
Results
Greater retention, as well as increased strength and accuracy, can be obtained using magneticattachments and CAD/CAM technology.