Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 900–905
Pressure production in oral vestibule during gum chewing M. NISHIURA*, T. ONO*†, M. YOSHINAKA*, S. FUJIWARA*, M. YOSHINAKA* & Y . M A E D A * *Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Osaka, and †Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
SUMMARY The aim of this study was to record oral vestibule pressure (OVP) by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The subjects were eight healthy adult men (mean age of 293 33 years). An experimental plate that incorporated four pressure sensors on the midline of the upper jaw (Ch. 1), upper right canine (Ch. 2), upper right first molar (Ch. 3) and upper left first molar (Ch. 4) was used for measuring OVP. The right masseter electromyogram (EMG) was recorded simultaneously. Subjects chewed gum on the right side 20 times, and eight consecutive strokes were used for the analysis of the sequential order, maximal magnitude and duration of each OVP. Onset of OVP was observed at the molar on the non-chewing side (Ch. 4) before chewing side (Ch. 3), and offset was largely simultaneous at each
Introduction Oral soft organs such as lips, cheeks and tongue work in coordination with jaw movement during food oral processing. For the lips, the orbicularis oris muscle demonstrates rhythmical activity matched to the opening phase, and this movement closes the oral fissure to keep food from escaping from the oral cavity, while the cheeks work in coordination with the tongue to move food from the oral vestibule to the occlusal table, primarily during the opening phase, and to keep it positioned between the upper and lower teeth. In earlier studies relating to jaw and tongue movements during chewing, detailed analysis was conducted using the mandibular kinesiograph (MKG) and © 2015 John Wiley & Sons Ltd
site. On the chewing side (Chs. 1–3), OVP onset during the interval of EMG activity reached to the peak around the end of interval and offset in the duration of EMG activity. The maximal pressure was significantly larger at Chs. 1–3 than at Ch. 4, but no significant differences were observed in duration of pressure among each site. These results suggest that OVP is coordinated with jaw movement during gum chewing, and larger pressure is produced on the chewing side than on the non-chewing side. Our findings are quantitative indices for the evaluation of lip and cheek function during mastication. KEYWORDS: mastication, lip pressure, cheek pressure, oral vestibule, pressure sensor, gum chewing Accepted for publication 7 June 2015
electromyograms (EMGs) (1), videofluorography (VF) (2) and tongue pressure measurement (3). However, the standardised methodology for evaluating the movement of oral surrounding soft tissues such as cheeks and lips has been yet to be established. Ever since it was first pointed out that oral soft tissue, such as the lips, cheeks and tongue, affects the positions of the teeth and plays an important role in forming and maintaining the dental arch (4), research has been carried out on the muscle pressure in the area around the oral cavity, from the standpoint of orthodontics and prosthodontics. Initially, it was only possible to measure the maximum force of the lips and tongue, but with advances in measurement devices, it became possible to record weaker forces, measurements of doi: 10.1111/joor.12328
LIP AND CHEEK PRESSURES DURING GUM CHEWING pressures during function, such as pressure at rest (5) and pressure during swallowing, pronunciation (6) and ingestion (7) could be measured. At the same time, when evaluating oral function in persons with physical or mental disabilities or stroke patients, attempts have been made to establish objective evaluation criteria by making videos of eating behaviour and assigning scores to lip and cheek movements (8). A variety of approaches like those described above are being used to evaluate lip and cheek movements, but extremely few studies have simultaneously evaluated lip and cheek movements during chewing (9). Therefore, this study aimed to evaluate the state of oral vestibule pressure (OVP) produced by lips and cheeks contraction during chewing. For this purpose, experimental plates with pressure sensors incorporated were attached to healthy dentate subjects and used to record the OVP produced during gum chewing and then these biomechanical characteristics and coordination with EMG activity of jaw closing muscle were investigated. The null hypotheses were that movements of lips and cheeks were not coordinated with jaw movement during chewing.
Materials & Methods Subjects Eight healthy subjects (mean age: 293 33 years) were recruited from among students at the Osaka University Graduate School of Dentistry. None had any history of disease causing neurological disease, temporomandibular disorder, removable prosthodontic treatment or orthodontic treatment. Subjects with prominent overbite (>5 mm), overjet (>5 mm) or malocclusions were excluded. All had Angle Class I and had not lost any teeth other than the third molar, and the habitual chewing side was the right side. This study received approval by the ethical committee of the Graduate School of Dentistry at Osaka University (H22-E24-1). Fabrication of experimental plate First, alginate impression material was used to take impressions of the maxillary dentition of all subjects, and working cast was then made with dental stone. Next, a vacuum former (Erkoform3D*) was used to pressure-fit
(a)
(b)
Fig. 1. Oral vestibule pressure measurement device and location points of pressure sensor. (a) Oral vestibule pressure measurement device and location of sensing points. Ch. 1; midline between the upper incisors, Ch. 2; upper right canine, Ch. 3; upper right first molar, Ch. 4; upper left first molar. (b) Placement of the pressure sensor in the mouth. All sensors were located at the cervix.
a plastic disc (Erkodule, thickness 08 mm*) to the working cast. The experimental plate was designed to cover an area from the distobuccal side of the upper right first molar to the distobuccal side of the upper left first molar and from the edge of the tooth to the widest contour of the alveolar part. The plate was adjusted and ground, making sure the frenulum and torus were clear. Four pressure sensors (PSM-1KAB, long diameter 35 mm, short diameter 30 mm, thickness 065 mm†) were affixed to the experimental plate. The sensors were affixed in four locations: at the midline (Ch. 1), the right canine (Ch. 2), the right first molar (Ch. 3) and the left first molar (Ch. 4), and all were located at the cervix of the tooth (Fig. 1). The pressure sensors were secured to plates made of gold and silver palladium alloy using adhesive (RC-19†) and then affixed to the experimental plate using dental paraffin wax. For all of the sensors, the surface bearing the pressure was no more than 2 mm from the tooth surface (10). To make sure that the cables of the sensors did not impede functional movement, they were secured to the experimental plate and routed to the exterior of the oral vestibule from the corners of the mouth. Denture adhesive (Poligrip‡) was applied at several points on the inner surface of the plates to fix
†
Kyowa Electronic Instruments Co., Ltd., Tokyo, Japan.
*Erkodent, Pfalzgrafenweiler, Germany. © 2015 John Wiley & Sons Ltd
‡
GlaxoSmithKline, Tokyo, Japan.
901
902
M . N I S H I U R A et al. them in place. In terms of calibration, outputs when seven different weights from 10 to 70 g were placed on each sensor were calculated, and the weight–output relationship was confirmed to be almost linear. Data recording In order for the subjects to become accustomed to the experimental plate, it was attached to the subjects two hours before measurement began. When measurements were conducted, a surface electrode was first attached to the right masseter. The experimental plate was then attached, and before starting measurement, the subjects chewed one piece of gum (Free Zone§), for 1 min, to make sure the gum was sufficiently soft. The gum had the property of being extremely resistant to sticking to teeth and experimental plate. The OVP and masseter EMG were recorded while the subject chewed 20 times. The experiment was performed in an examination room that did not contain any radio wave-emitting devices. The results were recorded using a personal computer via a sensor interface (PCD300A†). Next, to record the masseter activity, a surface electrode (Duotrode¶) was attached to the centre of right masseter, where the long axes of two electrodes were aligned parallel with the orientation of the muscle fibres. The output from the surface electrode was amplified 10 000 times using an amplifier (BA1104m**) and recorded to a personal computer (1000 Hz sampling rate) via a sensor interface (PCD320A†). Figure 2 shows a representative example of the OVP and masseter EMG waveforms. With respect to the OVP, after chewing was begun, pressure was observed at regular intervals on each channel, with largely monophasic peaks. Given that, the first few strokes after the start of measurement were eliminated, and a series of eight stable, consecutive strokes was used for the analysis described below. First, with respect to OVP, the maximal value and duration for each channel from the onset, peak and offset values of the waveform were calculated. Next, full-wave rectification waveform processing and smoothing were carried out for each of the EMG waveforms, and the
Fig. 2. Representative wave of oral vestibule pressure and masseter EMG (two chewing cycles extracted from eight cycles). The wave of oral vestibule pressure during gum chewing was monophasic peak. From the wave of oral vestibule pressure recorded, the order, duration and maximal magnitude were analysed.
times that the rectification waveform exceeded the mean amplitude of the baseline + 2s.d. for 1 s when at rest were defined as the onset and offset. The time from onset to offset was defined as the muscle activity time, while the time from offset to the offset of the next EMG waveform was defined as the chewing cycle. Statistical analysis To test the differences in the sequential order of OVP production at each measuring point, we used the Kruskal–Wallis test. To calculate the differences in durations and maximal magnitude of each measuring point, we used one-way ANOVA. After that, if a significant difference was observed, Dunn’s test was used for ordering and Tukey’s test was used for maximal magnitude and duration. Statistical processing was performed using SPSS Statistics 21†† and considered statistically significant was set at 5% in all cases.
§
Lotte Co., Ltd., Tokyo, Japan.
¶
Miotoronics, Kent, WA, USA.
**Nihonsanteku Co., Ltd., Osaka, Japan.
††
IBM, Chicago, IL, USA. © 2015 John Wiley & Sons Ltd
LIP AND CHEEK PRESSURES DURING GUM CHEWING
Results Sequential order of oral vestibule pressure production and masseter EMG activity Figure 3 shows the mean values of onset, peak and offset for the OVP for each channel and masseter activity time for all subjects. The offset of masseter activity just prior to onset of the OVP was set to 0 s. The onset of OVP was significantly slower for the midline (Ch. 1), the canine (Ch. 2) and the molar on the chewing side (Ch. 3) than offset of the masseter activity just before it, but no significant differences were observed between the offset of the masseter activity just prior to that and the onset of the molar on the non-chewing side (Ch. 4). The OVP for the each channel reached the peak level 019 007 s after onset, and the peak for Ch. 3 was significantly later than that for Ch. 4. The peak for Ch. 4 was significantly earlier than the time from the next onset of masseter activity (032 015 s from the offset of the preceding masseter activity). For each channel, offset was reached 020 007 s after peak, and no time differences were observed among the channels. This timing was significantly later than the onset of the next masseter activity and significantly earlier than offset. Each variability means standard deviation.
Fig. 4. Maximal magnitude of oral vestibule pressure. *Maximal magnitude of oral vestibule pressure at Chs. 1, 2, 3 were larger than Ch. 4, and Ch. 2 was larger than Chs. 1, 3 (P < 005).
Maximal magnitude of oral vestibule pressure Figure 4 shows the mean values for the maximal magnitude of OVP of each channel for all subjects. Comparisons showed significantly larger values for the midline (Ch. 1, 194 033 kPa), canine (Ch. 2, 393 059 kPa) and molar on the chewing side (Ch. 3, 205 032 kPa) compared to the molar on the nonchewing side (Ch. 4, 102 019 kPa), and the values for Ch. 2 were significantly larger than those for Ch. 1 and Ch. 3. Each variability means standard error. Duration of oral vestibule pressure The duration of OVP for the various channels was as follows: Ch. 1, 041 003 s; Ch. 2, 037 003 s; Ch. 3, 037 002 s; and Ch. 4, 039 003 s. No significant differences were seen among the channels. Each variability means standard error.
Discussion
Fig. 3. Sequential order of oral vestibule pressure production at each measuring points (Chs. 1–4) and masseter EMG activity during gum chewing. Offset of EMG prior to oral vestibule pressure was set to 0 s. (a, d) Onset at Chs. 1–3 was significantly later than offset at preceding EMG (P < 005). (b, c, e, f) Peak at Ch. 4 was significantly earlier than onset at EMG (P < 005). Offset at Chs. 1–4 was significantly later than onset at EMG and earlier than offset at EMG (P < 005). *Onset at Ch. 4 was significantly earlier than onset at Ch. 3 (P < 005). **Peak at Ch. 4 was significantly earlier than peak at Ch. 3 (P < 005). © 2015 John Wiley & Sons Ltd
This is an experimental study aiming to record OVP by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The null hypotheses that the movements of lips and cheeks are not connected with jaw movement during chewing were rejected. One technical advantage of the study was that the experimental plate was thin, at 08 mm, which helped to reduce the discomfort felt by the subjects when the plate was installed. This made it possible to record OVP that were produced during gum chewing in
903
Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 900–905
Pressure production in oral vestibule during gum chewing M. NISHIURA*, T. ONO*†, M. YOSHINAKA*, S. FUJIWARA*, M. YOSHINAKA* & Y . M A E D A * *Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Osaka, and †Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
SUMMARY The aim of this study was to record oral vestibule pressure (OVP) by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The subjects were eight healthy adult men (mean age of 293 33 years). An experimental plate that incorporated four pressure sensors on the midline of the upper jaw (Ch. 1), upper right canine (Ch. 2), upper right first molar (Ch. 3) and upper left first molar (Ch. 4) was used for measuring OVP. The right masseter electromyogram (EMG) was recorded simultaneously. Subjects chewed gum on the right side 20 times, and eight consecutive strokes were used for the analysis of the sequential order, maximal magnitude and duration of each OVP. Onset of OVP was observed at the molar on the non-chewing side (Ch. 4) before chewing side (Ch. 3), and offset was largely simultaneous at each
Introduction Oral soft organs such as lips, cheeks and tongue work in coordination with jaw movement during food oral processing. For the lips, the orbicularis oris muscle demonstrates rhythmical activity matched to the opening phase, and this movement closes the oral fissure to keep food from escaping from the oral cavity, while the cheeks work in coordination with the tongue to move food from the oral vestibule to the occlusal table, primarily during the opening phase, and to keep it positioned between the upper and lower teeth. In earlier studies relating to jaw and tongue movements during chewing, detailed analysis was conducted using the mandibular kinesiograph (MKG) and © 2015 John Wiley & Sons Ltd
site. On the chewing side (Chs. 1–3), OVP onset during the interval of EMG activity reached to the peak around the end of interval and offset in the duration of EMG activity. The maximal pressure was significantly larger at Chs. 1–3 than at Ch. 4, but no significant differences were observed in duration of pressure among each site. These results suggest that OVP is coordinated with jaw movement during gum chewing, and larger pressure is produced on the chewing side than on the non-chewing side. Our findings are quantitative indices for the evaluation of lip and cheek function during mastication. KEYWORDS: mastication, lip pressure, cheek pressure, oral vestibule, pressure sensor, gum chewing Accepted for publication 7 June 2015
electromyograms (EMGs) (1), videofluorography (VF) (2) and tongue pressure measurement (3). However, the standardised methodology for evaluating the movement of oral surrounding soft tissues such as cheeks and lips has been yet to be established. Ever since it was first pointed out that oral soft tissue, such as the lips, cheeks and tongue, affects the positions of the teeth and plays an important role in forming and maintaining the dental arch (4), research has been carried out on the muscle pressure in the area around the oral cavity, from the standpoint of orthodontics and prosthodontics. Initially, it was only possible to measure the maximum force of the lips and tongue, but with advances in measurement devices, it became possible to record weaker forces, measurements of doi: 10.1111/joor.12328
LIP AND CHEEK PRESSURES DURING GUM CHEWING
References 1. Takada K, Yashiro K, Sorihashi Y, Morimoto T, Sakuda M. Tongue, jaw, and lip muscle activity and jaw movement during experimental chewing efforts in man. J Dent Res. 1996;75:1598–1606. 2. Palmer JB, Rudin NJ, Lara G, Crompton AW. Coordination of mastication and swallowing. Dysphagia. 1992;7:187–200. 3. Hori K, Ono T, Nokubi T. Coordination of tongue pressure and jaw movement in mastication. J Dent Res. 2006;85:187–191. 4. Tomes CS. The bearing of the development of the jaws on irregularities. Dental Cosmos. 1873;15:292–296. 5. Di Fazio D, Lombardo L, Gracco A, D’Amico P, Siciliani G. Lip pressure at rest and during function in 2 groups of patients with different occlusions. Am J Orthod Dentofacial Orthop. 2011;139:1–6. 6. Kucukkeles N, Ceylanoglu C. Changes in lip, cheek, and tongue pressures after rapid maxillary expansion using a diaphragm pressure transducer. Angle Orthod. 2003;73:662–668. 7. Tamura F, Fukui T, Kikutani T, Machida R, Yoshida M, Yoneyama T et al. Lip-closing function of elderly people during
© 2015 John Wiley & Sons Ltd
8.
9.
10.
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12.
ingestion: comparison with young adults. Int J Orofacial Myology. 2009;V35:33–43. Caruso J, Stanhope J, McGuire A. A new technique for acquiring three-dimensional orofacial nonspeech movements. Dysphagia. 1989;4:127–132. Lundquist DO. An Electromyographic analysis of the function of the buccinators muscle as an aid to denture retention and stabilization. J Prosthet Dent. 1959;9:44–52. Gould MS, Picton DC. A method of measuring forces acting on the teeth from the lips, cheeks and tongue. Br Dent J. 1962;112:235–242. Casas M, Kenny D, Macmillan R. Buccal and lingual activity during mastication and swallowing in typical adults. J Oral Rehabil. 2003;30:9–16. Thuer U, Sieber R, Ingervall B. Cheek and tongue pressures in the molar areas and the atmospheric pressure in the palatal vault in young adult. Eur J Orthod. 1999;21:299–309.
Correspondence: Takahiro Ono, Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata 951-8514, Japan. E-mail: [email protected]
905
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 900–905
Pressure production in oral vestibule during gum chewing M. NISHIURA*, T. ONO*†, M. YOSHINAKA*, S. FUJIWARA*, M. YOSHINAKA* & Y . M A E D A * *Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Osaka, and †Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
SUMMARY The aim of this study was to record oral vestibule pressure (OVP) by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The subjects were eight healthy adult men (mean age of 293 33 years). An experimental plate that incorporated four pressure sensors on the midline of the upper jaw (Ch. 1), upper right canine (Ch. 2), upper right first molar (Ch. 3) and upper left first molar (Ch. 4) was used for measuring OVP. The right masseter electromyogram (EMG) was recorded simultaneously. Subjects chewed gum on the right side 20 times, and eight consecutive strokes were used for the analysis of the sequential order, maximal magnitude and duration of each OVP. Onset of OVP was observed at the molar on the non-chewing side (Ch. 4) before chewing side (Ch. 3), and offset was largely simultaneous at each
Introduction Oral soft organs such as lips, cheeks and tongue work in coordination with jaw movement during food oral processing. For the lips, the orbicularis oris muscle demonstrates rhythmical activity matched to the opening phase, and this movement closes the oral fissure to keep food from escaping from the oral cavity, while the cheeks work in coordination with the tongue to move food from the oral vestibule to the occlusal table, primarily during the opening phase, and to keep it positioned between the upper and lower teeth. In earlier studies relating to jaw and tongue movements during chewing, detailed analysis was conducted using the mandibular kinesiograph (MKG) and © 2015 John Wiley & Sons Ltd
site. On the chewing side (Chs. 1–3), OVP onset during the interval of EMG activity reached to the peak around the end of interval and offset in the duration of EMG activity. The maximal pressure was significantly larger at Chs. 1–3 than at Ch. 4, but no significant differences were observed in duration of pressure among each site. These results suggest that OVP is coordinated with jaw movement during gum chewing, and larger pressure is produced on the chewing side than on the non-chewing side. Our findings are quantitative indices for the evaluation of lip and cheek function during mastication. KEYWORDS: mastication, lip pressure, cheek pressure, oral vestibule, pressure sensor, gum chewing Accepted for publication 7 June 2015
electromyograms (EMGs) (1), videofluorography (VF) (2) and tongue pressure measurement (3). However, the standardised methodology for evaluating the movement of oral surrounding soft tissues such as cheeks and lips has been yet to be established. Ever since it was first pointed out that oral soft tissue, such as the lips, cheeks and tongue, affects the positions of the teeth and plays an important role in forming and maintaining the dental arch (4), research has been carried out on the muscle pressure in the area around the oral cavity, from the standpoint of orthodontics and prosthodontics. Initially, it was only possible to measure the maximum force of the lips and tongue, but with advances in measurement devices, it became possible to record weaker forces, measurements of doi: 10.1111/joor.12328
LIP AND CHEEK PRESSURES DURING GUM CHEWING pressures during function, such as pressure at rest (5) and pressure during swallowing, pronunciation (6) and ingestion (7) could be measured. At the same time, when evaluating oral function in persons with physical or mental disabilities or stroke patients, attempts have been made to establish objective evaluation criteria by making videos of eating behaviour and assigning scores to lip and cheek movements (8). A variety of approaches like those described above are being used to evaluate lip and cheek movements, but extremely few studies have simultaneously evaluated lip and cheek movements during chewing (9). Therefore, this study aimed to evaluate the state of oral vestibule pressure (OVP) produced by lips and cheeks contraction during chewing. For this purpose, experimental plates with pressure sensors incorporated were attached to healthy dentate subjects and used to record the OVP produced during gum chewing and then these biomechanical characteristics and coordination with EMG activity of jaw closing muscle were investigated. The null hypotheses were that movements of lips and cheeks were not coordinated with jaw movement during chewing.
Materials & Methods Subjects Eight healthy subjects (mean age: 293 33 years) were recruited from among students at the Osaka University Graduate School of Dentistry. None had any history of disease causing neurological disease, temporomandibular disorder, removable prosthodontic treatment or orthodontic treatment. Subjects with prominent overbite (>5 mm), overjet (>5 mm) or malocclusions were excluded. All had Angle Class I and had not lost any teeth other than the third molar, and the habitual chewing side was the right side. This study received approval by the ethical committee of the Graduate School of Dentistry at Osaka University (H22-E24-1). Fabrication of experimental plate First, alginate impression material was used to take impressions of the maxillary dentition of all subjects, and working cast was then made with dental stone. Next, a vacuum former (Erkoform3D*) was used to pressure-fit
(a)
(b)
Fig. 1. Oral vestibule pressure measurement device and location points of pressure sensor. (a) Oral vestibule pressure measurement device and location of sensing points. Ch. 1; midline between the upper incisors, Ch. 2; upper right canine, Ch. 3; upper right first molar, Ch. 4; upper left first molar. (b) Placement of the pressure sensor in the mouth. All sensors were located at the cervix.
a plastic disc (Erkodule, thickness 08 mm*) to the working cast. The experimental plate was designed to cover an area from the distobuccal side of the upper right first molar to the distobuccal side of the upper left first molar and from the edge of the tooth to the widest contour of the alveolar part. The plate was adjusted and ground, making sure the frenulum and torus were clear. Four pressure sensors (PSM-1KAB, long diameter 35 mm, short diameter 30 mm, thickness 065 mm†) were affixed to the experimental plate. The sensors were affixed in four locations: at the midline (Ch. 1), the right canine (Ch. 2), the right first molar (Ch. 3) and the left first molar (Ch. 4), and all were located at the cervix of the tooth (Fig. 1). The pressure sensors were secured to plates made of gold and silver palladium alloy using adhesive (RC-19†) and then affixed to the experimental plate using dental paraffin wax. For all of the sensors, the surface bearing the pressure was no more than 2 mm from the tooth surface (10). To make sure that the cables of the sensors did not impede functional movement, they were secured to the experimental plate and routed to the exterior of the oral vestibule from the corners of the mouth. Denture adhesive (Poligrip‡) was applied at several points on the inner surface of the plates to fix
†
Kyowa Electronic Instruments Co., Ltd., Tokyo, Japan.
*Erkodent, Pfalzgrafenweiler, Germany. © 2015 John Wiley & Sons Ltd
‡
GlaxoSmithKline, Tokyo, Japan.
901
902
M . N I S H I U R A et al. them in place. In terms of calibration, outputs when seven different weights from 10 to 70 g were placed on each sensor were calculated, and the weight–output relationship was confirmed to be almost linear. Data recording In order for the subjects to become accustomed to the experimental plate, it was attached to the subjects two hours before measurement began. When measurements were conducted, a surface electrode was first attached to the right masseter. The experimental plate was then attached, and before starting measurement, the subjects chewed one piece of gum (Free Zone§), for 1 min, to make sure the gum was sufficiently soft. The gum had the property of being extremely resistant to sticking to teeth and experimental plate. The OVP and masseter EMG were recorded while the subject chewed 20 times. The experiment was performed in an examination room that did not contain any radio wave-emitting devices. The results were recorded using a personal computer via a sensor interface (PCD300A†). Next, to record the masseter activity, a surface electrode (Duotrode¶) was attached to the centre of right masseter, where the long axes of two electrodes were aligned parallel with the orientation of the muscle fibres. The output from the surface electrode was amplified 10 000 times using an amplifier (BA1104m**) and recorded to a personal computer (1000 Hz sampling rate) via a sensor interface (PCD320A†). Figure 2 shows a representative example of the OVP and masseter EMG waveforms. With respect to the OVP, after chewing was begun, pressure was observed at regular intervals on each channel, with largely monophasic peaks. Given that, the first few strokes after the start of measurement were eliminated, and a series of eight stable, consecutive strokes was used for the analysis described below. First, with respect to OVP, the maximal value and duration for each channel from the onset, peak and offset values of the waveform were calculated. Next, full-wave rectification waveform processing and smoothing were carried out for each of the EMG waveforms, and the
Fig. 2. Representative wave of oral vestibule pressure and masseter EMG (two chewing cycles extracted from eight cycles). The wave of oral vestibule pressure during gum chewing was monophasic peak. From the wave of oral vestibule pressure recorded, the order, duration and maximal magnitude were analysed.
times that the rectification waveform exceeded the mean amplitude of the baseline + 2s.d. for 1 s when at rest were defined as the onset and offset. The time from onset to offset was defined as the muscle activity time, while the time from offset to the offset of the next EMG waveform was defined as the chewing cycle. Statistical analysis To test the differences in the sequential order of OVP production at each measuring point, we used the Kruskal–Wallis test. To calculate the differences in durations and maximal magnitude of each measuring point, we used one-way ANOVA. After that, if a significant difference was observed, Dunn’s test was used for ordering and Tukey’s test was used for maximal magnitude and duration. Statistical processing was performed using SPSS Statistics 21†† and considered statistically significant was set at 5% in all cases.
§
Lotte Co., Ltd., Tokyo, Japan.
¶
Miotoronics, Kent, WA, USA.
**Nihonsanteku Co., Ltd., Osaka, Japan.
††
IBM, Chicago, IL, USA. © 2015 John Wiley & Sons Ltd
LIP AND CHEEK PRESSURES DURING GUM CHEWING
Results Sequential order of oral vestibule pressure production and masseter EMG activity Figure 3 shows the mean values of onset, peak and offset for the OVP for each channel and masseter activity time for all subjects. The offset of masseter activity just prior to onset of the OVP was set to 0 s. The onset of OVP was significantly slower for the midline (Ch. 1), the canine (Ch. 2) and the molar on the chewing side (Ch. 3) than offset of the masseter activity just before it, but no significant differences were observed between the offset of the masseter activity just prior to that and the onset of the molar on the non-chewing side (Ch. 4). The OVP for the each channel reached the peak level 019 007 s after onset, and the peak for Ch. 3 was significantly later than that for Ch. 4. The peak for Ch. 4 was significantly earlier than the time from the next onset of masseter activity (032 015 s from the offset of the preceding masseter activity). For each channel, offset was reached 020 007 s after peak, and no time differences were observed among the channels. This timing was significantly later than the onset of the next masseter activity and significantly earlier than offset. Each variability means standard deviation.
Fig. 4. Maximal magnitude of oral vestibule pressure. *Maximal magnitude of oral vestibule pressure at Chs. 1, 2, 3 were larger than Ch. 4, and Ch. 2 was larger than Chs. 1, 3 (P < 005).
Maximal magnitude of oral vestibule pressure Figure 4 shows the mean values for the maximal magnitude of OVP of each channel for all subjects. Comparisons showed significantly larger values for the midline (Ch. 1, 194 033 kPa), canine (Ch. 2, 393 059 kPa) and molar on the chewing side (Ch. 3, 205 032 kPa) compared to the molar on the nonchewing side (Ch. 4, 102 019 kPa), and the values for Ch. 2 were significantly larger than those for Ch. 1 and Ch. 3. Each variability means standard error. Duration of oral vestibule pressure The duration of OVP for the various channels was as follows: Ch. 1, 041 003 s; Ch. 2, 037 003 s; Ch. 3, 037 002 s; and Ch. 4, 039 003 s. No significant differences were seen among the channels. Each variability means standard error.
Discussion
Fig. 3. Sequential order of oral vestibule pressure production at each measuring points (Chs. 1–4) and masseter EMG activity during gum chewing. Offset of EMG prior to oral vestibule pressure was set to 0 s. (a, d) Onset at Chs. 1–3 was significantly later than offset at preceding EMG (P < 005). (b, c, e, f) Peak at Ch. 4 was significantly earlier than onset at EMG (P < 005). Offset at Chs. 1–4 was significantly later than onset at EMG and earlier than offset at EMG (P < 005). *Onset at Ch. 4 was significantly earlier than onset at Ch. 3 (P < 005). **Peak at Ch. 4 was significantly earlier than peak at Ch. 3 (P < 005). © 2015 John Wiley & Sons Ltd
This is an experimental study aiming to record OVP by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The null hypotheses that the movements of lips and cheeks are not connected with jaw movement during chewing were rejected. One technical advantage of the study was that the experimental plate was thin, at 08 mm, which helped to reduce the discomfort felt by the subjects when the plate was installed. This made it possible to record OVP that were produced during gum chewing in
903
Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 900–905
Pressure production in oral vestibule during gum chewing M. NISHIURA*, T. ONO*†, M. YOSHINAKA*, S. FUJIWARA*, M. YOSHINAKA* & Y . M A E D A * *Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Osaka, and †Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
SUMMARY The aim of this study was to record oral vestibule pressure (OVP) by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The subjects were eight healthy adult men (mean age of 293 33 years). An experimental plate that incorporated four pressure sensors on the midline of the upper jaw (Ch. 1), upper right canine (Ch. 2), upper right first molar (Ch. 3) and upper left first molar (Ch. 4) was used for measuring OVP. The right masseter electromyogram (EMG) was recorded simultaneously. Subjects chewed gum on the right side 20 times, and eight consecutive strokes were used for the analysis of the sequential order, maximal magnitude and duration of each OVP. Onset of OVP was observed at the molar on the non-chewing side (Ch. 4) before chewing side (Ch. 3), and offset was largely simultaneous at each
Introduction Oral soft organs such as lips, cheeks and tongue work in coordination with jaw movement during food oral processing. For the lips, the orbicularis oris muscle demonstrates rhythmical activity matched to the opening phase, and this movement closes the oral fissure to keep food from escaping from the oral cavity, while the cheeks work in coordination with the tongue to move food from the oral vestibule to the occlusal table, primarily during the opening phase, and to keep it positioned between the upper and lower teeth. In earlier studies relating to jaw and tongue movements during chewing, detailed analysis was conducted using the mandibular kinesiograph (MKG) and © 2015 John Wiley & Sons Ltd
site. On the chewing side (Chs. 1–3), OVP onset during the interval of EMG activity reached to the peak around the end of interval and offset in the duration of EMG activity. The maximal pressure was significantly larger at Chs. 1–3 than at Ch. 4, but no significant differences were observed in duration of pressure among each site. These results suggest that OVP is coordinated with jaw movement during gum chewing, and larger pressure is produced on the chewing side than on the non-chewing side. Our findings are quantitative indices for the evaluation of lip and cheek function during mastication. KEYWORDS: mastication, lip pressure, cheek pressure, oral vestibule, pressure sensor, gum chewing Accepted for publication 7 June 2015
electromyograms (EMGs) (1), videofluorography (VF) (2) and tongue pressure measurement (3). However, the standardised methodology for evaluating the movement of oral surrounding soft tissues such as cheeks and lips has been yet to be established. Ever since it was first pointed out that oral soft tissue, such as the lips, cheeks and tongue, affects the positions of the teeth and plays an important role in forming and maintaining the dental arch (4), research has been carried out on the muscle pressure in the area around the oral cavity, from the standpoint of orthodontics and prosthodontics. Initially, it was only possible to measure the maximum force of the lips and tongue, but with advances in measurement devices, it became possible to record weaker forces, measurements of doi: 10.1111/joor.12328
LIP AND CHEEK PRESSURES DURING GUM CHEWING
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Correspondence: Takahiro Ono, Division of Comprehensive Prosthodontics, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata 951-8514, Japan. E-mail: [email protected]
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