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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 9  |  Issue : 2  |  Page : 111-114

The use of direct metal laser sintering technology in the management of acquired maxillofacial defects due to malignant neoplasm


Department of Prosthodontics, Kalinga Institute of Dental Sciences, KIIT University, Bhubaneswar, Odisha, India

Date of Submission07-Mar-2019
Date of Acceptance18-Nov-2019
Date of Web Publication3-Feb-2020

Correspondence Address:
Dr. Mousumi Panda
C/O Dr. Amitabh Panda, OMHS Dental Hospital, Gajapati Nagar Main Road, Bhubaneswar - 751 005, Odisha
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmd.ijmd_13_19

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  Abstract 


Rehabilitation of maxillary defects presents a significant challenge in terms of restoration of near normal functions following the healing of large surgical wound. The obturator prostheses as a part of prosthetic management are used for the separation of oral and nasal cavities to allow adequate deglutition and articulation and support for the soft tissue to restore the midfacial contour in palatal defect cases. This clinical report describes a prosthetic approach to the rehabilitation of an acquired palatomaxillary defect with definitive obturator prosthesis as well as guide flange prosthesis for the management of mandibular deviation.

Keywords: Laser sintering; maxillectomy; obturator; oroantral communication; rehabilitation


How to cite this article:
Panda M, Raut A, Hota S, Bhushan P. The use of direct metal laser sintering technology in the management of acquired maxillofacial defects due to malignant neoplasm. Indian J Multidiscip Dent 2019;9:111-4

How to cite this URL:
Panda M, Raut A, Hota S, Bhushan P. The use of direct metal laser sintering technology in the management of acquired maxillofacial defects due to malignant neoplasm. Indian J Multidiscip Dent [serial online] 2019 [cited 2020 Jun 5];9:111-4. Available from: http://www.ijmdent.com/text.asp?2019/9/2/111/277447




  Introduction Top


Acquired maxillofacial defects due to surgical treatment of neoplasms create oronasal/oroantral communication, leading to difficulties in mastication, hypernasal speech, fluid leakage, and cosmetic deformity and diminishing quality of life (QoL) and self-esteem.[1] An obturator is a maxillofacial prosthesis used to close congenital/acquired tissue opening of the hard palate and/or contiguous alveolar or soft-tissue structures. This clinical report describes a method for the fabrication of definitive obturator following hemimaxillectomy. Guide flange prosthesis was also fabricated for the management of mandibular deviation. The use of direct metal laser sintering (DMLS) technology has contributed to increased accuracy and precision.


  Case Report Top


A 35-year-old patient was referred to the Department of Prosthodontics, KIDS, Bhubaneswar, Odisha, India, for the fabrication of surgical obturator due to carcinoma of the buccal mucosa. Intraoral examination revealed an erythematous lesion 2 cm × 2 cm in the right maxillary third molar region and obliteration of mandibular right buccal vestibule following hemimandibulectomy 5 years ago. Clinicopathological examination revealed recurrent carcinoma of the right buccal mucosa and retromolar trigone. Medical history revealed squamous cell carcinoma (SCC) of the retromolar trigone. Environmental exposures (nickel refining and woodworking) and family history of malignant neoplasm might be the reason for head-and-neck SCC tumorigenesis.[2] Therefore, surgical closure using flap reconstruction was not advised owing to a history of recurrence.

Surgical resection was considered, followed by rehabilitation with obturator prosthesis. Presurgical impression of the maxillary arch was made using irreversible hydrocolloid (GC Corporation, Tokyo, Japan) and working cast prepared with Type III gypsum. The cast was duplicated to enable the maintenance of presurgical record and for the fabrication of surgical and interim obturator prosthesis. Mock surgery was performed on duplicated cast; surgical plate was fabricated integrating the clasps with heat-polymerizing acrylic resin (DPI, Mumbai, Maharashtra, India). Immediately after surgery, defect area examined, prosthesis disinfected using glutaraldehyde 0.2% solution before try-in procedure, and the prosthesis was delivered after minor adjustments. Routine follow-up appointments were scheduled for the examination of tissue healing and adjustment of obturator prosthesis.

After satisfactory healing, primary impression was repeated and interim obturator fabricated. For the correction of seepage/leakage owing to tissue shrinkage, interim obturator was repeatedly relined using tissue conditioners. After healing of surgical site [Figure 1], definitive obturator with the tripodal design was planned (Aramany Class II) [Figure 2]. Maximum mouth opening was 27 mm with deviated pattern. Border molding of lateral side defect was performed, and impression was made using polyvinyl siloxane impression material using a special tray [Figure 3].[3] Cingulum rests were prepared on 13 and 23 and occlusal rests on 24, 26, and 27 with clasps on 13, 23, 26, and 27.[4] After cast metal framework try-in [Figure 4], teeth arrangement was done to maintain palatal arch contour and for natural feel to the patient; processing was done and delivered [Figure 5]. Guide flange was planned for the management of mandibular deviation [Figure 6].[5] During prosthesis insertion, there was proper fitting of framework and no fluid leakage was observed from oronasal communication.
Figure 1: Postoperative intraoral healing with respect to the defect side

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Figure 2: Aramany Class II obturator design

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Figure 3: Elastomeric impression of the maxillary arch

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Figure 4: Metal framework on master cast

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Figure 5: Acrylized prosthesis in situ

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Figure 6: Mandibular guide flange

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  Discussion Top


Oral cancer is the sixth most common cancer worldwide, with a higher prevalence in South Asia.[6] SCC is a malignancy of the epithelium, occurs in organs covered with squamous epithelium. As it arises in a broad range of tissues, it represents the most common cancer capable of metastatic spread. The management is a multidisciplinary surgical approach with the integration of chemotherapy and radiotherapy; surgical approach toward tumor is influenced by primary site, location, size, proximity to bone, and depth of infiltration. This consequently disrupts the structure and activity of stomatognathic coordination. Functional rehabilitation and QoL regarding function, esthetics, psychological acceptance, and socialization after maxillofacial surgery depends on the outcome of maxillofacial reconstruction and rehabilitation.[7] Prosthetic obturator serves in lieu of Levin tube, rehabilitates maxillary resection by closing the defect, separating oral cavity from nasal cavity, preventing hypernasal speech, nasal regurgitation of food, and supporting facial profile.[8] Obturators were classified as surgical, intermediate, and definitive; design depends on the location and size of the defect, condition of residual bone and teeth, soft-tissue undercuts, and muscular control.

Surgical reconstruction is advantageous as it can cause permanent closure of oronasal connection. However, complications are debatable prognosis of vascularized flap with autogenous bone graft, especially for extensive defects. Furthermore, patients' motivation is necessary for second surgery, i.e., surgical wound at the donor's site for graft. Positive attributes of obturators include avoidance of added surgical procedure; follow-up can be done in case of recurrence, provision of teeth replacement, which can be planned after surgery.[9]

Heat-polymerizing acrylic resin is generally used as it exhibits ease of manipulation, superior hygiene, good color stability, durability, and tissue compatibility. It contributes to lightweight of prosthesis further improving cantilever mechanics of suspension, avoiding overburdening of the soft tissue, and adding resonance to speech. DMLS is the fabrication mechanism for the production of complex three-dimensional (3D) constituents directly from 3D-computer-aided designing (CAD) input without applying any machining and builds up framework in a sequence of consecutively thin layers (0.02–0.06 mm).

A conventional or digital impression of the maxillary/mandibular arch is made after customary diagnosis and treatment devising. In intermediate dental laboratory, impression casting and model preparation are done. Scanning of model and designing of framework are done using CAD and sent to the central processing unit with laser sintering machinery. Appropriate computer-aided manufacturing operating system is used to import a CAD file, provided in stereolithographic (STL) format from the scanner/CAD operating system. Metal particles are diffused over the operative platform. A high-powered laser beam (200 W Ytterbium fiber-optic lasers) is used to fuse a bed of metal alloy powder layer by layer around 20 μm thick. After builtup of all layers, retrieval of metal structures, sand blasting, polishing, and ultrasonic cleaning is done. Multiple unit structure generally can undergo distortion in the conventional approach; DMLS is more predictable with enhanced fitting. Time requisite in a dental laboratory is tremendously less. Precision of scanner (20 μm), effectiveness of the software in transforming scanning data into the 3D model, and precision of the milling machine affect the accuracy of fit.[10]

Therefore, highly complicated precise frameworks are obtained from 3D-CAD data, with greater accuracy, detailed resolution, excellent surface quality, and mechanical characteristics (density 99.9% ensuing high strength, free from porosity, thus providing consistent quality and strength). Therefore, palatal obturator restores mastication, swallowing, articulation, intelligibility of speech, and contour of midface and improves QoL. Rehabilitation with obturator prosthesis is functional, reliable, easy to fabricate and has a low level of invasiveness. DMLS helps in increasing accuracy and detailed resolution, excellent surface quality, and exceptional mechanical properties.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Acknowledgment

The authors acknowledge the faculty and technicians of the Department of Prosthodontics, KIDS, Bhubaneswar, Odisha, India.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Keyf F. Obturator prostheses for hemimaxillectomy patients. J Oral Rehabil 2001;28:821-9.  Back to cited text no. 1
    
2.
Yan W, Wistuba II, Emmert-Buck MR, Erickson HS. Squamous cell carcinoma – Similarities and differences among anatomical sites. Am J Cancer Res 2011;1:275-300.  Back to cited text no. 2
    
3.
Aramany MA. Basic principles of obturator design for partially edentulous patients. Part I: classification. J Prosthet Dent 1978;40:554-7.  Back to cited text no. 3
    
4.
Parr GR, Tharp GE, Rahn AO. Prosthodontic principles in the framework design of maxillary obturator prostheses. J Prosthet Dent 1989;62:205-12.  Back to cited text no. 4
    
5.
Babu S, Manjunath S, Vajawat M. Definitive guiding flange prosthesis: A definitive approach in segmental mandibulectomy defect. Dent Res J (Isfahan) 2016;13:292-5.  Back to cited text no. 5
    
6.
Chinn SB, Myers JN. Oral cavity carcinoma: Current management, controversies, and future directions. J Clin Oncol 2015;33:3269-76.  Back to cited text no. 6
    
7.
Khandelwal A, Neeli A, Gadiyar A, Khandelwal A. Assessment of quality of life of patients 1-5 years after treatment for oral cancer. Indian J Dent Res 2017;28:538-44.  Back to cited text no. 7
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8.
Bin Jamayet N, Pokpong A, Theerathavaj S, Alam MK. Management of a maxillectomy patient by definitive obturator. Int Med J 2013;20:460-1.  Back to cited text no. 8
    
9.
Wang B, Zhang S, Yue K, Wang XD. The recurrence and survival of oral squamous cell carcinoma: A report of 275 cases. Chin J Cancer 2013;32:614-8.  Back to cited text no. 9
    
10.
Venkatesh KV, Nandini VV. Direct metal laser sintering: A digitised metal casting technology. J Indian Prosthodont Soc 2013;13:389-92.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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