Indian Journal of Dental Research

: 2013  |  Volume : 24  |  Issue : 4  |  Page : 507--510

Modified snap-on attachment with 'O-ring' for two piece hollow bulb obturator

C Gunasekar1, KS Gamal Abdul Nasser2, C Sabarigirinathan2, K Ram Kumar2,  
1 Department of Dentistry, ESIC Hospital & Post Graduate Institute of Medical Science and Research, Chennai, Tamil Nadu, India
2 Department of Dentistry, Tamil Nadu Government Dental College, Chennai, Tamil Nadu, India

Correspondence Address:
C Gunasekar
Department of Dentistry, ESIC Hospital & Post Graduate Institute of Medical Science and Research, Chennai, Tamil Nadu


Restoration of near normal functions in patients who have been treated with hemimaxillectomy is generally difficult, in view of the restriction in mouth opening following healing of large surgical wound. Further, the extent and nature of the surgical defect differ from patient to patient. Thus, design of an obturator needs to be patient oriented. In this report, we describe a novel snap-on attachment with O-ring in a conventional two piece hollow bulb obturator for a 70-year-old male treated for carcinoma of the left maxilla and sinus.

How to cite this article:
Gunasekar C, Gamal Abdul Nasser K S, Sabarigirinathan C, Kumar K R. Modified snap-on attachment with 'O-ring' for two piece hollow bulb obturator.Indian J Dent Res 2013;24:507-510

How to cite this URL:
Gunasekar C, Gamal Abdul Nasser K S, Sabarigirinathan C, Kumar K R. Modified snap-on attachment with 'O-ring' for two piece hollow bulb obturator. Indian J Dent Res [serial online] 2013 [cited 2021 Nov 29 ];24:507-510
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Full Text

Maxillary defects may occur as a result of tumor surgery or congenitally. The prosthesis that restores the maxillary defect was termed as an obturator. [1] The obturator prosthesis that closes these defects and separate the oral and nasal cavities may be constructed in different sizes and shapes, depending on the extent of the defect in order to restore functional, esthetic and emotional affect. [2]

Obturators are classified as solid, open hollow and closed hollow as to the nature of their extensions into the surgical defect site. [3],[4],[5],[6],[7],[8] Both open and closed hollow obturators allow for the fabrication of a lightweight prosthesis that can be tolerated by the patient while effectively extending into the defect. [9] However, the weight of prosthesis may act as a dislodging force in a larger surgical defect and result in failure to establish the desired functions.

Although a number of conventional obturators are available, [10] this obturator may not be ideal for a given patient. It is therefore desired an obturator that encompass the functional requirement of a conventional obturator but should serve retention without unduly increasing the weight of the obturator. The purpose of this report was to describe a novel snap-on attachment with O-ring in a conventional two piece hollow bulb obturator for a 70-year-old male treated for carcinoma of the left maxilla and sinus with limited mouth opening.

 Case Report

This clinical report describes the prosthodontic rehabilitation of 70-year-old man with a history of hemi-maxillectomy for squamous cell carcinoma of the left maxilla. He was subsequently rehabilitated with definitive single piece hollow bulb obturator [Figure 1]. However, he presented six months later with the complaint that he was unable to insert the obturator. Clinical examination revealed the tissue contracture at the posteriolateral aspect of the defect along with the formation of scar band, leading to trismus and patient's inability to insert the obturator. In view of the present clinical condition, it was decided to provide two piece hollow bulb obturator with a modified snap-on attachment using food grade silicone 'O-ring' as a retentive aid. {Figure 1}


Stage 01

Preliminary impression with alginate was taken, working cast made and a thin hollow bulb fabricated with heat cure polymerizing acrylic resin, which was tried-in mouth and trimmed at the level of palate.

Stage 02

Secondary impression was taken by the alginate with bulb. That was boxed and split cast method used to pour stone cast [Figure 2].{Figure 2}

A empty 3M light body syringe tube [Figure 3] was used for fabricating the snap-on attachment by separating the tube with disc and the inner piston and outer tube end were used for attachment by making wax pattern and converting them into heat cure acrylic resin. The O-ring supplied with the tube was of medical-grade silicone (which has better retention properties), but because food-grade silicone had better stiffness and hardness, we used a food-grade O-ring.{Figure 3}

The female part was positioned in the bulb at the level of palate and poured the salt in the hollow bulb around the female part and closed with auto polymerizing resin [Figure 4]. Then the salt was remove with bur hole and closed with self-cure resin. {Figure 4}

The male part was oriented and trimmed at level of 1.5 mm away from the palatal portion of the bulb which merges in 2 mm thickness of the dental prosthesis [Figure 5] separating medium applied over the palatal portion of the bulb and attachment and fabricate self-cure resin base.{Figure 5}

Stage 03

Bite rim was made and bite registration were taken with bulb then transferred to articulator along with bulb to avoid any occlusal discrepancy. Arrangement of teeth and wax trial were done, clasp assembly made on near defect and far away from defect and additional retention clasp on 16 also provided.

Stage 04

The dental prosthesis was processed with heat cure acrylic resin. The food grade O-ring was placed on the male attachment and was used as retentive aid, [Figure 6] the two piece hollow bulb obturator with snap-on O-ring attachment were delivered to patient.{Figure 6}


In this report, we describe the construction of a two piece hollow bulb obturator with a modified snap-on attachment with O-ring, to unite the obturator and the dental prosthesis. The literature show that there are only limited techniques and methods available to provide retentive aids within a conventional hollow-bulb obturator, like magnets and snap-on (friction type) attachments. These retentive techniques are wrought with the disadvantage of corrosive or magnetic field effects [10] [Gillings et al., see within V Bhatt article]. This may lead to decrease in the thickness of the original magnets, leading to inadequate contact between the two magnets, resulting in loss of retention.

Although, O-ring attachment have been employed as a retentive aid in the dental prostheses of an obturator, [11] the use of O-ring with snap-on attachment between the prostheses and obturator have not been described before to the best of our knowledge.

In practice, the medical grade silicone used in various forms for the purpose of extra and intra-oral prostheses. Although, medical silicone is ideal with regard to biocompatibility, their mechanical properties are not adequate for retentive usage to employ in a two-piece hollow-bulb obturator prostheses. The medical grade silicone was indeed employed initially but the retention obtained was not adequate enough in the present case. This limitation stem from their reduced stiffness and hardness as result of more modulus of elasticity. In contrast, food grade silicone employed subsequently provided better retention in view of the stiffness/hardness required for retentive placements. 12 Another difficulty encountered was however, their biocompatibility remains a concern although, no proven side effects have been ascribed to their use. Nevertheless, this may not be a problem as the silicones do not come into contact with living oral tissues, as described in this report. Further, the chemical and mechanical properties of the food grade silicone are an added advantage when compared to medical silicone.

As evident from the techniques described in the literature, the snap-on attachments are usually placed with the male portion in the obturator and the female portion in the dental prosthesis, which may lead to accumulation of secretions. [1] On the other hand, the technique employed here, where the female portion was placed in the obturator and the male portion with O-ring attachment in the dental prostheses would eliminate the accumulation of secretions. It is also more effective when the mouth opening is limited and the surface area of the defect is larger to provide adequate retention. Generally, more number of magnets or snap-on attachments are required to provide stability and retention for two piece hollow-bulb obturator, especially when the obturator covers a larger surgical defect. [10] This would increase the weight of the obturator and may not serve the desired results. In contrast, the single attachment described here would not only provide better retention but also allow the patient easily to orient the position without undue difficulty.

Furthermore, it is functionally compatible with the tissues in the defective areas by means of stress-breaking effects. An additional advantage of this technique is that the use of an all acrylic fabrication with no metal component considerably reduces the weight of the obturator. It is also easy to fabricate, cost effective and can be maintained by the patient. This single attachment made for better retention and easy to wear without difficulties to orient the position [Figure 7].{Figure 7}

There seems to be no disadvantages from this technique but the O-ring on food grade silicone is to be observed for any changes in their properties or to the patients' health status, as well as the O-ring and how long it can be retained and the need for change of O-ring yet to be verified.

In the present case, the use of this technique to fabricate an obturator which is light in weight, technically more feasible, economical, easily cleansable and more retentive and to give better post-operative life conditions to this patient, having limited opening mouth with large defect.

To the best of our knowledge this technique was not described in the literature.

The two-piece hollow-bulb obturator with snap-on 'O-ring' attachment presented satisfactory occlusion, good retention and stability with light weight, and the patient reported a feeling of comfort and satisfaction of his demands. [Figure 8]. We also provided nasal lip prosthesis for the patient [Figure 9].{Figure 8}{Figure 9}


Treatment of maxillary acquired defect is based on an understanding of the accepted principles, concepts and practices of prosthodontics, augmented by expanded knowledge of anatomy, physiology, pathology, the functional compensation of residual tissue, and a psychosocial evaluation, with compassionate management.

To provide secure obturator prosthesis is necessary for satisfactory quality of life after maxillectomy and make ability to perform everyday activities with patient's satisfaction.


We readily acknowledge our indebtedness to Prof. Dr. C. Tulasingam, MDS.


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