The 23rd International Conference on Magnetic Applications in Dentistry (Feb. 26 to Mar 15, 2024)
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Retention of a speech-aid prosthesis with a magnetic attachment in apatient with cleft lip and palate: A case report
M Hattori, M Murase, Y Mouri, S Matsui, B Li, J Wada, N Wakabayashi
Department of Advanced Prosthodontics, Graduate School of Medical and Dental Sciences,
Tokyo Medical and Dental University (TMDU)
Abstract
This report describes a case in which insufficient remaining teeth impacted the effectiveness ofmaxillofacial prosthetic rehabilitation and reports on the applicability of magnetic attachments
for the retention of dentures equipped with speech aids. This method is aimed at improving thestability and functionality of these dental prostheses. A 75-year-old woman with velopharyngeal
dysfunction due to left maxillary cleft lip and palate presented with an unstable maxillary
overdenture equipped with a speech aid, which had a disengaged O-ring attachment on the left
maxillary central incisor. It was replaced with a magnetic attachment and the speech-aid
prosthesis was adjusted. Functional evaluation was performed with the adjusted prosthesis, and asignificant reduction in nasalance during speech was observed. Assessment of masticatory
performance demonstrated that the patient could eat a wide variety of foods without substantial
difficulty. The magnetic attachment was weak against lateral force, but it improved tongue
comfort compared with the O-rings when the prosthesis was not in use. Further discussion andconsideration of the effective use of magnetic attachments in maxillofacial prosthetics is expected.
Introduction
Effective maxillofacial prosthetic rehabilitation can be challenging due to insufficiency of theremaining teeth, which can impact the stability and function of the appliances. To address thischallenge, one method being explored is the use of magnetic attachments in maxillofacial

prosthetic appliances. These attachments could potentially improve oral functions and enhance
retention and stability1-3). In this report, we describe a case in which magnetic attachments wereused for the retention of a speech-aid-equipped denture. This method was chosen to reduce thedifficulties encountered in maintaining the stability and functionality of this type of dentalprosthesis.
Case Report
Patient Characteristics
The patient was a 75-year-old woman who presented in September 2022 with a chief[Web Presentation] PS2-1-1

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complaint of instability in her speech-aid-equipped maxillary overdenture and difficulties inverbal articulation and mastication. She had dysfunctional velopharyngeal closure due to left
maxillary cleft lip and palate, with partially edentulous maxillary and mandibular arches (Fig.
1). The O-ring attachment on the left maxillary central incisor had become dislodged causing
instability of the maxillary overdenture.

Fig. 1 Panoramic X-ray of the upper and lower jaws.
Clinical History
The patient was born with a cleft palate and subsequently underwent palatoplasty and speechtherapy. In the mid-1960s, a speech aid was fabricated at our institution for the patient. Aroundtwenty years later, following fracture of this speech aid, the patient consulted our university’s
department of oral surgery and was then referred to our advanced prosthodontics department forinitial consultation and examination. After the initial consultation, a speech-aid-equippedmaxillary partial denture was fabricated, and the patient attended regular follow-up. However,progressive tooth decay and periodontal disease led to a gradual decrease in her remaining teeth.
In response to these changes, a new speech-aid-equipped partial denture was fabricated andadjusted on four occasions to accommodate her evolving dental status. Figure 2 shows thecondition of the oral cavity and the speech-aid-equipped partial denture as of 2003.

Fig. 2 Intraoral and extraoral views and the speech-aid-equipped partial denture (2003).

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The 23rd International Conference on Magnetic Applications in Dentistry (Feb. 26 to Mar 15, 2024)
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Treatment Plan
Treatment that utilized the existing speech aid denture was planned. We detailed the anticipatedadvantages and disadvantages4) of using a magnetic attachment for the left maxillary central
incisor and obtained the patient’s consent for this treatment.
Materials and Methods
In accordance with standard procedures, the left maxillary central incisor was prepared(utilizing the existing posts) and an impression was made (Exafine Regular, GC). A magnetic
attachment keeper (Magfit M, Aichi Steel) was then installed using Super-Bond (Super-Bond,Sun Medical)(Fig. 3). A pathway was created in the speech-aid-equipped overdenture, and amagnet was attached to the denture. The magnet was set using immediate polymerization resin(Unifast III, GC)(Fig. 4). After adjustments, we conducted a series of functional evaluations,focusing on speech intelligibility, masticatory performance, and denture stability and the patient's
satisfaction with the denture.

Fig. 3 Intraoral view with a magnetic attachment keeper on the left maxillary central incisor(2023).

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The 23rd International Conference on Magnetic Applications in Dentistry (Feb. 26 to Mar 15, 2024)
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Fig. 4 The fabricated speech aid with a magnetic attachment in place (2023).
Functional Evaluation
Masticatory Performance Evaluation: Objective Food-Comminuting Ability
Masticatory performance5) was assessed by measuring the concentration of dissolved glucose
from a gummy jelly (Glucolumn, GC). The patient was instructed to masticate the gummy jelly
for 20 s, rinse with 10 mL of distilled water, and expectorate the masticated particles into a filter
net within a cup. The resultant filtrate was then gathered, and the glucose concentration released

from the fragmented gummy jelly was precisely measured using a portable blood glucose meter(Glucosensor GS-II, GC).
Masticatory Performance Evaluation: Objective Food-Mixing Ability
We used color-changeable chewing gum (Xylitol, Lotte) (70 mm × 20 mm × 1 mm, 3.0 g), toassess masticatory performance in relation to food mixing6). For a specified duration of 1 min, thepatient was asked to chew the gum and then the specimen was collected immediately aftermastication. The a* and ΔE1min values were obtained by measurements using a colorimeter (CR13, Konica-Minolta Sensing).
Masticatory Performance Evaluation: Subjective Perceived Chewing Ability
The patient’s perception of chewing ability was assessed using a food intake questionnaire 7)[Web Presentation] PS2-1-4

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consisting of a list of 35-food items divided into 5 categories based on hardness of the food andrated in relation to ease of eating. To describe masticatory ability using the questionnaire,Masticatory Score was calculated as the sum for the 5 categories of the total points in eachcategory multiplied by a difficulty factor, and then the Masticatory Score was expressed as apercentage of this value out of the maximum possible.
Lip-Closure Strength Evaluation
The lip-closure strength was measured as the force-resisted by the device while pulling thetightly closed lips, using a digital strain force gauge (Lipplekun, Shofu) as previously described8).
Denture Satisfaction Evaluation
The patient completed the self-rated Denture Satisfaction Questionnaire9), which uses a visual
analog scale, to systematically evaluate critical facets of her prosthetic experience, encompassing
masticatory functions, such as eating and chewing efficiency, as well as the impact of theprosthesis on facial esthetics and speech intelligibility. In addition, an overall satisfaction metric
was included to capture a comprehensive appraisal of her denture use.
Digital Acoustic Analysis: Formant Frequency Evaluation
Digital acoustic analysis of five Japanese vowels, (/a/, /i/, /u/, /e/, /o/) and uttered sounds wererecorded using a speech analysis system (Computerized Speech Lab CSL4500, Kay Pentax).
Acoustic analysis was performed using sound analysis software (Computerized Speech Lab, KayPentax). The ranges of the first two formants were determined by calculating the difference
between the minimum and maximum formant frequencies among the five vowels10).
Digital Acoustic Analysis: Nasalance Evaluation
Nasalance, defined as the ratio of acoustic energy of speech sounds emanating from the nasal
cavity relative to that from the oral cavity, was measured using a nasometer (Nasometer II, KayPentax) while the patient enunciated the monosyllables /i/, and /tsu/, sentence with low vocal
pressure, sentence with high vocal pressure and mixed-content sentence11).
Results
The patient reported that tongue sensation was more favorable with the magnetic attachment
than with the O-ring attachment when she was not wearing the prosthesis. She complained thatthe speech-aid-equipped overdenture (Fig. 4) tended to dislodge when lateral forces were applied,so adjustments were made to the pressure distribution of the denture by reattaching the magnet
on two occasions. However, no improvement was observed.

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The patient’s lip-closure strength was 11.7 N, surpassing the established minimal requisite of
6 N and the targeted optimal level of 10 N. In addition, her masticatory performance was evaluatedby multiple methods. Objective food-comminuting ability, an indicator of effectiveness inbreaking down food, was measured as 160.3 mg/dL, greatly exceeding the benchmark of 100
mg/dL. The objective food-mixing ability values were ΔE of 58.4 and a* of 30.2. Complementing
these objective evaluations, the patient’s subjective chewing ability was appraised in terms ofMasticatory Score as 79.8%. This comprehensive evaluation shows a marked improvement inoral functionality, which is attributed to the speech-aid-equipped overdenture with magneticattachment, which enabled the patient to eat a wide variety of foods without major difficulties.
The range of formant 1, 2 and 3 when prosthesis was worn were 646.83, 2022.05 and 731.2 Hz,
and those when prosthesis was not worn were 569.65, 1609.41 and 871.38 Hz respectively. The
range was sufficient to distinctly articulate and differentiate the five vowels, indicating adequate
articulatory function. Most notably, the incorporation of the denture with a speech aid wascorrelated with significant enlargement of the range of the third formant. This change in the
acoustic parameters suggests a potential improvement in nasopharyngeal function, which is a
critical factor in articulation and thus speech intelligibility.
The implementation of a denture equipped with a speech aid led to a decrease in nasalance(Fig. 5). This reduction was particularly pronounced in the average nasalance values associatedwith the articulation of high-pressure sounds and mixed-content sentences. This notable decreasein nasalance is indicative of enhanced efficiency in nasopharyngeal closure, suggesting functional
improvement of the velopharyngeal mechanism as a result of prosthetic treatment.

Nasalance（％）
100806040200/i/
without prosthesis highest/tsu/

low pressure

without prosthesis meanhigh pressure

with prosthesis highest

mixedwith prosthesis mean

Fig. 5 The result of nasalance test.
The patient's satisfaction with the denture was high, particularly in relation to masticatory
function, such as eating and chewing efficiency, as well as the ’impact of the prosthesis on facial
appearance and speaking (Fig. 6).

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Visual Analogue Scaleprosthesis
speaking
appearance
chewingeating020406080100Fig. 6 The result of visual analogue scale.
Discussion
The magnetic attachment, while offering a superior tactile experience compared with the Oring attachment, showed a tendency for the denture to dislodge under lateral forces. Despite this,the integration of a magnetic attachment with the speech-aid-equipped overdenture markedly
improved nasopharyngeal closure and articulation, and also enabled the patient to eat of a wide
variety of foods. This comprehensive treatment approach resulted in a high degree of patientsatisfaction.
Conclusion
In this patient with cleft lip and palate, the incorporation of a magnetic attachment in a speechaid-equipped denture demonstrated substantial functional rehabilitation. However, a notablechallenge was the attachment’s susceptibility to lateral forces. Therefore, ongoing research anddevelopment in this domain is needed to enhance the effectiveness and therapeutic potential ofmagnetic attachments in maxillofacial prosthetic applications.

References
1. Parthasarathy N, Anusha Ks, Madhan KS, Natarajan S. Maxillary Defect Rehabilitation Using aHollow Bulb Obturator. Cureus. 2022;14(11):e31326.
2. Won AM, Montgomery P, Aponte-Wesson R, Chambers M. Implant-supported and magnet-retainedoral-nasal combination prosthesis in a patient with a total rhinectomy and partial maxillectomy due tocancer: A clinical report. J Prosthet Dent. 2017;117(2):315-320.
3. Gupta D, Thakkur R, Shah B. A case report on implant retained auricular prosthesis: Bringing back[Web Presentation] PS2-1-7

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hope and smile. Natl J Maxillofac Surg. 2023;14(1):152-156.
4. Umekawa Y, Kokubu M, Ishigami T. Influence of keeper tilt angle on retentive force of magneticattachment. J J Mag Dent. 2007;16(2):10–13.
5. Shiga H, Kobayashi Y, Katsuyama H, Yokoyama M, Arakawa I. Gender difference in masticatory
performance in dentate adults. J Prosthodont Res. 2012 Jul;56(3):166-169.
6. Ishikawa Y, Watanabe I, Hayakawa I, Minakuchi S, Uchida T. Evaluations of masticatory
performance of complete denture wearers using color-changeable chewing gum and other evaluating
methods. J Med Dent Sci. 2007 Mar;54(1):65-70.
7. Hirai’s Food Intake Questionnaire with 35 Foods Listings, Int J Prosthodont 1994;7:454-460.
8. Takamoto K, Saitoh T, Taguchi T, Nishimaru H, Urakawa S, Sakai S, Ono T, Nishijo H. Lip closure
training improves eating behaviors and prefrontal cortical hemodynamic activity and decreases
daytime sleep in elderly persons. J Bodyw Mov Ther. 2018 Jul;22(3):810-816.
9. Sato M, Yatabe M, Ai M, Wakabayashi N, Nakamura K. Evaluation of Patients’ Satisfaction with
Their New Denture. J Jpn Prosthodont Soc. 1999;43:871-876.
10. Elbashti ME, Sumita YI, Hattori M, Aswehlee AM, Taniguchi H. Digitized Speech Characteristics
in Patients with Maxillectomy Defects. J Prosthodont. 2019;28(6):649-655.
11. Hattori M, Sumita YI, Taniguchi H, Nasalance in Maxillectomy Speech Using Monosyllables asStimuli. Maxillofacial Prosthetics (Japanese journal with English abstracts). 2013;36(1):34-38.

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