This document summarizes several journal articles related to sensors for managing xerostomia or dry mouth in patients with maxillofacial prostheses. The first article describes a new technique for fabricating a dental prosthesis with an embedded sensor that detects dry mouth and releases artificial saliva in response. Subsequent articles evaluate different types of sensors for measuring tongue pressure and oral moisture levels, and explore relationships between oral dryness and medical treatments like radiation therapy. The final article discusses the development of a 3D printed sensor for selectively detecting ammonium ions in artificial saliva mixtures.

1. JOURNAL CLUB PRESENTATION
NEERAJA M MENON
COORG INSTITUTE OF DENTAL SCIENCES

2. A salivary sensor for the management of
Xerostomia in edentulous patients
Karthikeyan V, Chander NG, Anitha KV. J Prosthet Dent 2018
AIM: This article describes a method for managing xerostomia in edentulous patients with a newly developed
salivary sensor.

3. Content
INTRODUCTON
MATERIALS AND METHODS
RESULTS
DISCUSSION
SUMMARY
CONCLUSION
RELATED ARTICLES

4. Introduction
 Saliva is an important oral fluid for mastication, swallowing, taste perception,
lubrication, and buffering action and improves patient comfort when present in
adequate quantity and quality.
 The retention and stability of an obturator prosthesis even with adequate salivary
presence is compromised because of the loss of the resected diseased tissues inside the
oral cavity. Thus, the presence of saliva contributes to the effectiveness of the
maxillofacial prosthesis.
 The rehabilitation of acquired maxillofacial defects requires an interdisciplinary
approach as the patients present with many difficulties.
 The effectiveness of each therapeutic measure overrides its limitations. Xerostomia or
dryness of mouth from the lack of normal secretions is one of the major limitations of
radiation therapy.

5.  Such patients should receive immediate palliative care. Various management strategies
have been suggested for xerostomia, including gustatory and pharmacological means of
increasing salivary flow and the use of mouthwash, chewing gum, lozenges, oral
buffering products, artificial salivary substitutes, lubrication sprays, rinses, and
acupuncture.
 In spite of the availability of numerous topical oral sialogogues, there is no strong
evidence for the superiority of one over others. This present report puts forward a new
dental technique wherein an obturator prosthesis was made with an inbuilt sensor for
the management of xerostomia.

6.  Sensors are those devices that detect physical, chemical, and biological signals and
provide a way for those signals to be analyzed and recorded. They give information
about signals which could not be otherwise directly detected by the senses and can
sense physical properties such as temperature, pressure, vibration, sound level, or light
intensity.
 Among the many available sensors, pressure sensors can measure gases or liquids and
express the force required to stimulate the flow of a fluid.

7. Materials and Method
Block extreme undercuts with baseplate wax
Use dental stone to make the preliminary cast
Make a preliminary impression of the maxillectomy defect
Fabricate a custom tray

8. Bead and box the definitive impression with wax
Make a definitive impression with monophase polyvinyl siloxane impression
material
Complete the denture waxing
Arrange the teeth for verification of the trial prosthesis
Make an interim denture base using autopolymerizing polymethyl methacrylate resin

9. Adapt a 3-mm thickness of modeling wax onto the palatal defect area to create a shim.
After dewaxing, use a 3-mm thickness of modeling wax to block out the undercuts in the
cast
Invest the cast with dental plaster and eliminate the wax by boiling
Evaluate the passive seating of the part of the flask
Create a ledge around the periphery of the defect with wax to leave an opening to
the defect portion.

10. Now bevel the acrylic resin borders around the defect area and adapt a sheet of light-
polymerizing acrylic resin sheet to cover this portion
Separate the processed flasks
After wax elimination, pack the flask with heat polymerizing polymethyl methacrylate denture
base resin to obtain a hollow shim and palatal portion of the denture with teeth
Before light polymerizing the adapted resin sheet, gently scrape and remove the
projection of dental plaster in the defect area just enough to accommodate the sensor
component.
Take another flask cope and seat it over the flask drag containing the definitive cast, fill
it with dental plaster, and dewax

11. Tube for addition of artificial salivary substitute.Components of sensor unit.

12. Pack using heat-polymerizing polymethyl methacrylate denture base resin to secure
Evaluate both units of the flask for passive fit
Place the processed base containing the sensor unit onto the initial flask with the
teeth
With the sensor unit in place, use autopolymerizing acrylic resin to close the opening
between the denture base and light cure resin sheet.
Inject 20 mL of artificial saliva substitute through the tube connected to the silicone
pouch

13. Sensor placed within prosthesis.

14. Discussion
The technique described in this report is a way to fabricate a dental prosthesis with
inbuilt microsensors for ejection of artificial saliva. The prosthesis contains a
micropressure sensor unit and a transduction unit to convert the input signal into
output source.
The input signal is mouth dryness, and the output action is ejection of the incorporated
saliva substitute. The micropressure sensor works on the principle of mechanical
bending of a thin silicon diaphragm by tongue pressure.

15. Summary
A removable dental prosthesis was fabricated with inbuilt sensors to help in the
management of xerostomia.
A micropressure sensor was incorporated into the prosthesis to detect a dry mouth. On
detecting a dry mouth, tongue pressure ejects artificial saliva from a capsule inside the
sensor.
The addition of a small sensing unit helps with detection of the dry mouth.
Saliva substitute is released according to the requirement of the patient and
unnecessary dispensing and frequent replacement of artificial saliva is avoided.

16. Conclusion
This sensor prosthesis can help patients overcome mouth dryness, improves patient comfort,
and aids in retention of the prosthesis.
Although sensors play an essential role in artificial prostheses for capturing senses, their
application is still in its infancy.

17. RELATED ARTICLES

18. Newly developed sensor sheet for measuring
tongue pressure
during swallowing
Hori K, Ono T, Tamine K, Kondo J, Hamanaka S, Maeda Y, Dong J, Hatsuda M. J Prosthodont
Res. 2009
Aim: The aim of this study was to develop a sensor sheet for measuring tongue pressure during swallowing
and to clarify its usefulness by comparing it with a conventional pressure sensor installed in the palatal plate

19. Materials And Methods
AT-shaped sensor sheet with five measuring points
(3.0 mmin diameter) was designed based on
preceding studies using electric pressure sensors.
The sensor sheet attached to the palatal mucosa directly with a sheet
type denture adhesive.

20. In order to standardize the position of each measuring point, 60
maxillary diagnostic casts were morphologically analysed.
Anatomical landmarks such as incisive papillae (P)and hamular
notch were identified and Hm was defined as the midpoint
between Hr and Hl on the maxillary cast. M, Lr, and Ll were
defined as the one-third posterior on P-Hm, P-Hr, and P-Hl,
respectively.
Therefore, the path of the cable was designed to be a circle Lr
and B which was the point on the buccal side of alveolus at the
same height as Lr and Ll.

21. Comparison of pressure output characteristics between the sensor sheet and a pressure
sensor
To compare the pressure output under the same load, one of the measuring points of the sensor
sheet was placed on a pressure sensor.
A randomized load was applied to a measuring point of the sensor sheet and the output values
of both sensors were recorded.
The relationship between the output values of both sensors were statistically analyzed

23. The completed sensor sheet with three sizes.

24. Characteristics of maximum magnitude of tongue pressure during swallowing recorded by the sensor
sheet
Thirty healthy volunteers (20 men and 10 women) were included in the test.
The sensor sheet was attached to the palatal mucosa directly with a sheet shaped denture adhesive
(Touch correct II, Shionogi, Osaka, Japan) during the recording of tongue pressure.
Tongue pressure production during the swallowing of 15 ml water was recorded with the subjects sitting
on the chair in the upright position. The subject’s head was supported by the head-rest of the chair so
Frankfort Plane was parallel to the ground. At the recording time, the subject was given the sign to
swallow.
The maximum magnitude of tongue pressure (MP) at each measuring point was evaluated from the
waveform of each recording.

25. Results
1. Comparison of pressure output characteristics between the sensor sheet and a pressure
sensor
Although the output value of the sensor sheet was lower than that of the pressure sensor, they
showed quite a high correlation.
2. Characteristics of maximum magnitude of tongue pressure (MP) during swallowing
recorded by the sensor sheet
Tongue pressure was generated initially by close contact with the anterio-median part, then the
circumferential part, and finally softly with the posterio-median part. Tongue pressure reached a
peak quickly, then decreased gradually before disappearing almost simultaneously at each
measured part of the hard palate.

26. Representative rare wave of tongue pressure recorded by the sensor
sheet placed in the oral cavity.

27. MP was significantly larger in the anterior-median part (Ch. 1) compared with that at the other
four measuring parts, and significantly smaller in the posterior-median part (Ch. 3)

28. MP at each measuring point recorded by the sensor sheet (10.0–14.5 kPa) was smaller than that
recorded by pressure sensors installed in the palatal plate (19.4–25.6 kPa).

29. Discussion
Tongue pressure against the hard palate was measured with pressure sensors for evaluating tongue
movement during mastication and swallowing. Miniaturized pressure sensors enabled researchers to
install a number of sensors in an experimental palatal plate or a maxillary denture.
The thinness of the tactile sensorsheet was considered to be effective for reducing discomfort in the oral
cavity.
Results of the clinical trial of the sensor sheet in 30 healthy subjects showed superiority of tongue
pressure production at the anterio-median part of the hard palate (Ch. 1) both in the sequential order of
onset and the maximal magnitude.
Hence, this study suggests that a sensor sheet system was useful in the quantitative evaluation of tongue
activity during oropharyngeal swallowing.

30. Relationship between medical treatment and
oral dryness diagnosed by oral moisture-
checking device in patients with maxillofacial
prostheses
Aim: To examine the relationship between oral dryness and medical treatment (medication,
radiotherapy) for patients with maxillofacial prostheses.
Mamoru Murakami, Yasuhiro Nishi
Yuji Kamashita, Eiichi Nagaoka J Prosthodont Res 2017

31. Materials and Methods
A total of 16 patients with maxillofacial prostheses were included in the study.
Current medication use and radiotherapy history – dose of radiation and period after radiation –
were surveyed from their clinical records.
A patient with a maxillofacial prosthesis needs a method for examination of oral dryness without
the burden of chewing something. Methods which do not involve chewing anything include the
Saliva Wet Tester and Moisture Checker Mucus
Oral moisture was measured at the lingual mucosa (the surface of the tongue 10 mm from the
apex linguae) and at the right and left buccal mucosa (10 mm from the angle of the mouth)
A value of 29% was defined as normal and was used as a reference value to divide subjects into
the normal group and the oral dryness group, with anything less than 29% being defined as oral
dryness.

32. An oral moisture-checking device (a) and measurement points (b:
lingual mucosa, c: buccal mucosa).

33. The patients rated themselves for feeling of oral dryness according to explanations using a faces
scale.
The faces scale consisted of seven drawings of faces numbered in order of varying feelings of
oral dryness, from no feeling (smiling face) to a severe feeling of dryness (tearful face).

34. Results
Figure 1 shows that the average moisture value (29.03 1.43%) for the females did not
significantly differ from that (29.06 1.42%) of the males.
Figure 2 shows that the average moisture value (27.95 0.93%) for the oral dryness group was
significantly lower than that (30.14 0.65%) for the normal group (P < 0.01).

35. In the oral dryness group, the numbers of patients with radiotherapy treatment was significantly
higher than those without radiotherapy. Conversely, the number of patients with radiotherapy
treatment was significantly lower than those without radiotherapy in the normal groups

36. There was no significant difference between the numbers of patients with and without
medication in the respective oral dryness and normal groups.

37. The moisture value showed a significant negative correlation with the score of the faces scale

38. Discussion
Using a Moisture Checker Mucus, Takahashi et al. reported the oral moisture at the lingual and
buccal mucosa for 13 healthy adults and 13 patients with subjective oral dryness.
Consequently, the mean moisture values at the lingual mucosa and buccal mucosa (30.0 0.5%,
30.3 0.2%) in the healthy adults group were significant higher than those (28.6 1.1%, 29.6
0.7%) in the oral dryness group.
In the present study, the differences in moisture values between the normal group and the oral
dryness group showed the same result.
These results suggest that patients with maxillofacial prostheses who have undergone
radiotherapy need moisture retention because of oral dryness depending on the dose of
radiation and the period after radiation.

39. Toward a highly selective artificial saliva sensor
using printed hybrid field effect transistors
Bao C, Kaur M, Kim WS. Sensors and Actuators B: Chemical. 2019
Aim: To develop a feasible 3D printing method to fabricate flexible Ion selective field effect
transistors (ISFETs) by hybridization of printed organic ion selective electrodes and inorganic
transistors and the possibility of the hybrid ISFETs for NH4+ detection in artificial saliva from the
mixture of interference ions.

40. Materials And Methods
Fabrication of printed field effect transistor (FET).
Fabrication of Ion selective electrode.
Fabrication of Ion selective membrane.
Preparation of artificial saliva
Made by mixing sodium chloride (13.2 mg), potassium chloride (96.4 mg), calcium chloride (17.2
mg), potassium phosphate monobasic (65.0 mg), urea (20.4 mg), and lactic acid (17.4 mg)
together in 100 ml distilled water. Then, different concentration of ammonium ion solution was
prepared with the basic artificial solution.

41. Characterization
Each concentration solution was transferred from vial to the sensor area by micropipette,
following 1 min data recording. The open circuit potential was collected by potentiostat with a
0.1 s sample interval for 1 min. The images of printed FET electrode were performed by
microscope NJF-120 A with 4X objective lens

42. Results
The calibration curve for Vd-Log for NH4+ concentration was obtained. A clear linear relation
between the drain voltage and NH4+ concentration was observed. It demonstrated distinct
selectivity of the fabricated ISFETs even with interference of multiple ions.

43. Conclusion
The high selectivity of ISFETs with mixture of interference ions concentration in artificial saliva
was confirmed which expands the possibility of wearable ISFETs for real-time monitoring in
biological or medical applications.
This capability provides an integrated platform for a comprehensive ion analysis by closely
monitoring interrelated saliva parameters as wearable healthcare solutions manufactured by 3D
printing methods.