A novel speech prosthesis for mandibular guidance therapy in hemimandibulectomy patient: A clinical report.

Treating diverse maxillofacial patients poses a challenge to the maxillofacial prosthodontist. Rehabilitation of hemimandibulectomy patients must aim at restoring mastication and other functions such as intelligible speech, swallowing, and esthetics. Prosthetic methods such as palatal ramp and mandibular guiding flange reposition the deviated mandible. Such prosthesis can also be used to restore speech in case of patients with debilitating speech following surgical resection. This clinical report gives detail of a hemimandibulectomy patient provided with an interim removable dental speech prosthesis with composite resin flange for mandibular guidance therapy.

Introduction

Surgical resection involving floor of the mouth, tongue and mandible in hemi mandibulectomy patients with mandibular discontinuity leads to numerous complications. With the uncompensated influence of contralateral muscles, deviation of the mandible toward the resected side occurs resulting in eccentric occlusion, a disoriented masticatory cycle, distorted speech, and facial disfigurement. A number of case reports in the literature have used various prosthetic methods such as palatal ramp, mandibular guide flange, intermaxillary fixation, and vacuum-formed polyvinyl chloride pipe splints. These devices have been used to return the mandible to an optimum maxillomandibular relationship.[1]

More specifically, reduced oral cavity with the removal of varying amounts of mandible or teeth may be a consequence post hemimandibulectomy, which could also compromise articulation of tongue resulting in sound distortion and speech defects.[2] The cause of such sound distortions is often due to restricted motions of the tongue and lack of lingual-palatal contact required for the sounds “k” and “g.” Since contact between the tongue and the posterior part of the palate is anatomically impossible, a prosthesis can be functionally formed to lower the palatal vault.[3]

The palatal augmentation prosthesis (PAP) has been defined by a glossary of prosthodontic terms as a palatal prosthesis that allows reshaping of the hard palate to improve tongue/palate contact during speech and swallowing because of impaired tongue mobility as a result of surgery, trauma, or neurologic/motor deficits.[45] The PAP allows the palatal vault to be re-established at a lower level than normal, requiring less bulk, and mobility of the tongue for appropriate palatolingual contacts during speech and swallowing.[4] Using this principle, this clinical report describes the fabrication of an interim removable dental speech prosthesis with composite resin flange for mandibular guidance therapy for a patient following hemimandibulectomy.

Case Report

A 55-year-old male patient reported to the Department of Prosthodontics, with a complaint of inability to chew and inability to speak clearly. Patient's history revealed right mandibular resection, surgical operation for squamous cell carcinoma of right buccal mucosa, and radiation therapy about a month back.

Extra-oral examination revealed deviation of the mandible toward right side with 32 corresponding to 12 on 25 mm of mouth opening. Maximum mouth opening was observed to be 25 mm and the perimeter as 4.5 cm. Deviation of the tongue toward the resected side was also observed. However, no reconstructive surgery was done.

Intra-oral examination showed missing 13, 14, 15, 16, 17, 27, 37, 43, 44, 45, 46, and 47. There was total obliteration of the lingual sulcus on the right side. The mandibular defect was classified as Cantor and Curtis Class III,[6] i.e., resection defect involved loss up to the mandibular midline region [Figures 1 and 2].

Figure 1

Preoperative photograph

Figure 2

Orthopantamograph

A speech prosthesis and palatal guide flange prosthesis was planned for the patient.

A stainless steel stock dentulous tray and irreversible hydrocolloid (Neocolloid; Zhermack) was used to record preliminary impression of both the mandibular and maxillary arches. The casts were poured with Type III gypsum material (Goldstone; Rajkot) and were retrieved. A maxillomandibular record was made by manually assisting the mandible close to desirable mandibular position. The maxillary and mandibular casts were then mounted on an articulator. A 19 gauge hard, round, stainless steel orthodontic wire (Gloria Enterprise, Mumbai) was manipulated to adapt C-clasps on 12, 26, and 28 for providing retention for the prosthesis. A trial base in self-cure acrylic resin was fabricated and occlusal plane checked in the patient's mouth. Try-in of the maxillary removable partial denture was carried out. At the try-in stage, a thin layer of zinc oxide (Deepashree products MIDC, Ratnagiri) and saline mix was painted on the palatal surface of the removable partial denture with a camel hair brush to know the areas where the tongue made contact with the palate. It was observed that there was not much of contact between the lateral borders of the tongue and the palate [Figure 3]. The palatal surface of the prosthesis was later covered with tissue conditioning material and left for molding.

Figure 3

Application of zinc oxide powder and saline

Lighter prosthesis was proposed in this clinical report to reduce the weight of the prosthesis. Chalian technique[7] was followed to make the prosthesis lighter [Figure 4a-d]. The removable partial denture with the speech prosthesis was given to the patient for 2 months. Once the patient got accustomed to the prosthesis, a palatal ramp was made in composite resin. Left side of the palate was roughened and treated with primer and cured. The conditioned region was coated with core build-up material (LuxaCore-Z, DMG, Hamburg, Germany). The patient was asked to protrude the tongue and mandible was guided to desired position thus the core build up material got functionally molded by the tongue on the medial aspect and the mandibular teeth on the lateral aspect. Medial side of the ramp followed contour of the lateral border of the tongue; thus, ramp did not interfere with the tongue. The material was cured intraorally, finished and inserted [Figures 5 and 6]. The patient was advised to use the guide flange prosthesis throughout the day, except at night and during meals.

Figure 4

(a-d) Steps to make prosthesis hollow

Figure 5

Speech prosthesis with palatal ramp

Figure 6

Postoperative photograph

The patient was asked to come for regular follow-up to make adjustments to accommodate increased mobility or hypertrophy of the articulating tissues based on input from the patient, family members, and the speech pathologist.

Patient reported being more comfortable with swallowing after insertion of the speech prosthesis. Interim prosthesis has advantages of ease of processing, better acclimatization for patient, and cost effective. However, the success of the prosthesis depends on history of radiation therapy, patient compliance, initiation of guidance therapy, and nature of surgical defect. After a follow-up of 3 weeks, definitive prosthesis can be planned in the form of cast partial prosthesis.

Discussion

Prosthetic guiding flanges have been reported often in the literature that were used to rehabilitate patients with surgical resection. Patil and Patil[8] reported a case of reconstructed hemimandibulectomy patient with a modified mandibular guided flange prosthesis and a maxillary stabilization plate made of wire-reinforced heat polymerized acrylic resin to enhance patients' speech and mastication. Bhattacharya et al.[1] reported a case of maxillary palatal ramp prosthesis to manage mandibular deviation following segmental mandibulectomy. The palatal ramp was trial made in wax followed by processing in heat polymerized acrylic resin, which was later modified with autopolymerizing acrylic resin. Sahu[9] used a guidance flange on the buccal side and the supporting flange on the lingual side as a mandibular guidance following resection. In a case reported by Sahin et al.,[10] a cast metal guidance prosthesis with supporting flanges and retentive flanges was fabricated following a segmental mandibulectomy.[9] Joshi et al.[11] described the fabrication of a removable mandibular guide flange prosthesis as an effective alternative for most patients with mandibular defects, considering the poor prognosis, difficulty in decision making for the use of the implant and economic feasibility. Prencipe et al.[12] described a technique by which only one mandibular prosthesis was used for both physiotherapy and chewing, by simply inserting and removing the guide flange with two precision attachments on the buccal surface of the denture base with their patrix and the corresponding matrixes in the transparent guide flange.

Although guide flange helps in repositioning the mandible for prosthetic treatment, the accommodation of speech also remains one of the goals of prosthetic rehabilitation. Apart from mandibular discontinuity, restricted tongue movements, radiation therapy could lead to a change in volume and consistency of saliva that makes prolonged speech discourse difficult and misarticulation of speech sounds. Use of palatal speech aids was suggested by Cantor et al. in 1969.[3] According to their study, consonant sounds such as/k/and/g/require valving by posterior part of the tongue with the posterior part of the hard palate and anterior portion of the soft palate and such consonant sounds were particularly difficult for mandibulectomy patients.[3] But if the palatal vault was lowered prosthetically into the space of donders to accommodate for restricted tongue movements, speech improvement may be noted. Others observed that placement of prosthesis although improves the quality of specific sounds, it does not improve the discourse. However, intensive speech therapy does improve speech significantly both with and without prosthesis.[3] Meyer et al.[13] reported using light-cured resin to make an interim PAP. Tissue conditioning material was used in the present case to mold the palatal vault of the prosthesis which can help in a better articulation of linguopalatal sounds in the patient.

Very few case reports have been published in the literature on dual use of guide flange designed as a speech aid prosthesis. Hagino et al.[14] investigated the factors influencing the outcome of speech therapy in patients with mandibulectomy without glossectomy. Speech intelligibility test and acoustic features were investigated on patients with and without prosthesis with a self-administered questionnaire. The results were corelated with tongue movements, amount of soft tissue grafting and bone continuity. Ease of tongue movements, the absence of soft tissue grafting and presence of bone continuity contributed to better recovery of speaking ability with prosthodontic treatment thus emphasizing the importance of speech rehabilitation along with mandibular correction.[10]

In the present case report, tissue conditioner mixed to a thick, moldable consistency to lower the palatal vault was preferred because of their ease of handling and adjustment. Chalian technique was used to make it hollow to reduce the bulk of the prosthesis. A dual cure light cure material was used to make the palatal ramp as it gave adequate time to mold the ramp by the lateral border of the tongue and the mandibular teeth hence it did not interfere with the movements of the tongue.

Conclusion

Rehabilitation of patients is of paramount importance to a maxillofacial prosthodontist. Prosthetic devices can restore several functions such as mastication, swallowing, speech, and esthetics. Guidance flange prosthesis with a custom molded palatal surface aids in better articulation of speech sounds, which can potentially enhance the quality of life of patients who have undergone surgical resection.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.