ADVANCES IN DENTAL PRODUCTS |
THE EFFECT OF DENTURE ADHESIVE
ON MANDIBULAR MOVEMENT DURING CHEWING
JILL K. RENDELL, M.P.H.,
THOMAS GAY, PH.D.,
JOSEPH E. GRASSO, D.D.S., M.S.D.,
ROBERT A. BAKER, M.S. and
J. LESLIE WINSTON, D.D.S., PH.D.
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ABSTRACT
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Background. The authors conducted a study to determine if reducing mandibular denture movement through the use of a denture adhesive improves chewing function in edentulous patients.
Methods. The authors compared the mean chewing rates of 10 denture wearers who used and did not use a denture adhesive with that of a control group of 10 dentate people. The authors recorded mandibular movements using a multichannel magnetometer tracking system while the subjects chewed standardized pieces of dried apricots and fresh white bread. They made recordings for the test subjects without the use of denture adhesive and at zero, two and four hours after Fixodent denture adhesive cream (Procter & Gamble Co.) was applied to the mandibular denture.
Results. The mean chewing rate for the control group was significantly faster than that of the test group at baseline (P < .01). The authors found statistically significant increases in the mean chewing rates for the test group after the denture adhesive was applied at all time points for both foods. None of the after–adhesive-application rates were significantly different from the control group’s rate (P > .05).
Conclusions. Use of denture adhesive increased the mean chewing rate in test subjects immediately after and at two and four hours after denture adhesive was applied to a rate that approximated that observed in control subjects (P > .05).
Clinical Implications. These findings show that using a denture adhesive promotes a faster and more natural rate of chewing.
It has been shown that using denture adhesive significantly reduces the movements of the mandibular and maxillary dentures during chewing, biting and speaking.1–6 It is not known, however, if the reduction in movement is accompanied by a corresponding improvement in these functions.
Of particular importance to denture wearers is retention during chewing. Chewing is produced by a quasi-rhythmical set of cyclical mandibular opening and closing movements in which considerable forces are applied to the mandibular and maxillary dentures. If a reduction in denture movement produces an improvement in chewing function, it should be revealed by changes in the kinematic properties of mandibular opening and closing during the cycle. Perhaps the simplest kinematic property of mandibular function to study is chewing rate. Another, although less-quantifiable, parameter is the smoothness of the trajectory of the mandible during opening and closing.
We conducted this study to compare the kinematic properties of mandibular movements in a group of denture-wearing test subjects with those of dentate control subjects. We also wanted to determine if differences in chewing rate existed between the two groups, and, if differences did exist, whether the application of a denture adhesive minimized those differences.
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MATERIALS AND METHODS
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Subjects.
Control subjects comprised five men and five women with natural teeth who ranged in age from 39 to 66 years (mean = 54.6 years). These dentate subjects had no evidence of oral pathology and did not wear any partial removable prostheses. Test subjects comprised six men and four women who ranged in age from 48 to 85 years (mean = 61.0 years) and who had complete maxillary dentures and implant-supported mandibular dentures. All dentures had been fabricated recently and were classified as well-fitting.
The study’s inclusion criteria required all test subjects to demonstrate a minimum amount of measurable mandibular denture movement (2 millimeters) while chewing a dried apricot during baseline measurements. Exclusion criteria included any evidence of obvious oral pathology as determined by the study dentist (J.E.G.), an allergy to either of the food types, or any health condition that would prevent compliance with not consuming nonstudy food during the four-hour experimental session. The rights of all subjects were protected through the University of Connecticut Health Center’s Institutional Review Board approval; each subject read and signed a consent form.
Data recording.
We used a multichannel magnetometer (MoveTrack, Botronics) to measure the rate of mandibular movement during chewing. The vertical movements of separate receiver coils were tracked relative to a transmitter coil mounted on a headband. The flux density of the alternating magnetic field is inversely proportional to the distance between the transmitter coil and the receiver coils. Receiver modules condition the signal detected by each receiver coil and convert it to a lineal distance. The output of each module consists of a direct current signal that is proportional to the distance between the two coils.
In this study, we used one receiver coil located on a mandibular implant post and one located on the mandibular denture. A mandibular denture was constructed for each subject and contained a relief area that exposed the implant posts so that the posts no longer provided retention for the denture but served as an attachment point for the receiver coil that measured mandibular movement. We recorded the outputs of each receiver module channel on a digital cassette recorder.
We tested dried apricots and fresh white bread because they represent sticky food types that are problematic for denture wearers.
Experimental protocol.
We recorded mandible movements while each subject chewed a 3-gram piece of dried apricot and then a 3-g piece of fresh white bread. We selected dried apricots and fresh white bread because they represent sticky food types that are problematic for denture wearers.
We first made baseline recordings for the test subjects under conditions in which no denture adhesive cream was applied to the prostheses. Then the study dentist removed each test subject’s denture and applied Fixodent denture adhesive cream (Procter & Gamble Co.). For the test subjects, we made recordings for the apricot and the bread immediately after, at two hours after and at four hours after denture adhesive application. We made one recording for each control subject.
Data analysis.
We converted the signals stored on the digital cassette recorder from analog to digital using a laboratory microcomputer. All data were displayed and analyzed using a signal acquisition and analysis program. We recorded the number of chewing strokes for the first 10 seconds of each chewing task and then converted this value to chewing strokes per minute. We also visually examined the raw signals to make a qualitative determination of the naturalness and regularity of the mandibular movement.
We used two sample t-tests to make between-group comparisons for the control group vs. the test group at all time points. We used paired-sample t-tests for within-group comparisons of the test group at baseline vs. each after–adhesive-application time point. We confirmed the results of these between-group and within-group tests using nonparametric Wilcoxon rank sum and Wilcoxon signed rank tests, respectively.
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RESULTS
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Effects of denture adhesive on chewing rate. The control group’s mean chewing rate for dried apricots was 83.6 strokes per minute ± 18.5 standard deviation, or SD, compared with 60.8 strokes per minute ± 6.0 SD for the test group at baseline (Table
). This difference was statistically significant (P < .01), indicating that without the use of a denture adhesive, the test group’s mean chewing rate was significantly slower than that of the control group.
After denture adhesive was applied, the test group’s mean chewing rate increased for each time point, reaching a maximum of 78.3 strokes per minute ± 10.8 SD at two hours after adhesive application. The chewing rate increased for all 10 test subjects at each after–adhesive-application time point compared with baseline. All within-group differences between baseline and each time point were statistically significant (P < .01). Differences between the control group and the test group at each after–adhesive-application time point, however, were not statistically significant (P > .05). This suggests that the use of the denture adhesive helped the test group achieve a mean chewing rate comparable to that of the control group.
We obtained comparable results using fresh white bread. Differences in chewing rate for the two food types were not significant at any time point.
Effect of denture adhesive on mandibular kinematics.
We made qualitative judgments about the naturalness or smoothness of the opening and closing trajectories of the mandible based on a display of the mandibular movement signal. The mandibular trajectories of all 10 control subjects appeared smooth and regular. Of the 10 test subjects, we judged six to have irregular opening-closing trajectories at baseline.
Figure 1 shows the opening and closing movements of the mandible during a chewing task for a control subject. A downward movement of the line corresponds to mandibular opening, and an upward movement corresponds to mandibular closing. Note that the general pattern of movement is rhythmic and smooth during both phases of the cycle. This is typical for normal chewing.
Figure 2 shows a comparable pattern for a test subject at baseline. Here, the blue line plots the trajectory of the mandible, and the red line plots the trajectory of the mandibular denture for the same chewing task. Note that the mandibular movement trajectory is irregular, particularly during the closing phase of the cycle when food contact is made. This is especially true for cycles 1 and 3. Note also the separation of the mandibular denture from the base, or residual ridge, during most of each cycle. The mandibular denture begins to separate from the base shortly after the mandible begins to open and remains separated from the base until the point of occlusion, except in cycle 2. This separation probably is caused by the adhesive properties of the food the denture comes into contact with during compaction. Maximum separation is reached at maximum mandibular opening. Note that during closing, mandibular denture movement is not smooth, and cycles 1, 3 and 4 show what might be a rocking component during closing, which probably occurs at the point of food contact. It appears that at this point, the rocking causes the denture to make contact with the ridge. At occlusion, the mandibular denture is forced against the mandible, and the two are in contact with each other.
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Figure 2. Trace of mandible and mandibular denture opening and closing cycles for denture wearer without a denture adhesive present, illustrating irregularities of both denture and mandibular motions.
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Figure 3 shows the movement trajectory of the mandible and mandibular denture for the same subject immediately after denture adhesive was applied. It is clear that separation of the denture from the base is greatly reduced, and there is virtually no irregularity in the trajectory of either the mandible or mandibular denture.
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Figure 3. Trace of mandible and mandibular denture opening and closing cycles for denture wearer with a denture adhesive present, illustrating the effect of the adhesive on minimizing denture movement and smoothing mandibular trajectory.
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DISCUSSION
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There are multiple issues related to the clinical significance of a denture adhesive, but most important is its efficacy in improving function and its effect on the health of the underlying tissues. Reduction in denture movement after the application of denture adhesive has been well-documented in the literature.1–5 The relationship between improved denture retention and improved function, however, has not been demonstrated previously.
In this study, we focused on two functional indicators: one quantitative (chewing rate) and one qualitative (mandibular kinematics). These, of course, are not the only relevant indicators of chewing function.
Although denture adhesives are used by millions of denture wearers and are advocated by many professionals as an over-the-counter product,7–10 their use has not been generally accepted as part of the dental professional’s treatment plan. While some professionals and denture wearers consider them a useful aid to denture retention, others view them as a poor substitute for a proper-fitting prosthesis.11,12 There also is a concern that the use of a denture adhesive might promote tissue changes—including residual ridge bone resorption11—and, as a result, have a negative effect on occlusion.12
Previous studies have shown that well-fitting and poor-fitting dentures are subject to movement even without the use of a denture adhesive,5,6,13 and that a denture adhesive significantly reduces movement in even well-fitting maxillary and mandibular dentures.5,6 The results of this current study are consistent with those findings and further suggest that improved retention of well-fitting dentures helps achieve improved function.
This study’s data showed that the chewing patterns of six test subjects were characterized by consistently irregular movement trajectories (Figure 2
). These irregularities appeared in the movements of both the mandible and the mandibular denture; the latter exhibited a presumed rocking component at the time of food contact in which the denture probably made contact with the base. This would suggest the possibility of increased, as opposed to decreased, tissue trauma and consequent ridge resorption of the mandibular base. Among these six subjects, denture adhesive use reduced or eliminated what probably was repeated contact between the denture and base during the chewing cycle, and most likely produced a decrease in the likelihood of tissue trauma. This is not consistent with the views of clinicians who associate the use of a denture adhesive with an increase in tissue trauma.11,12
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CONCLUSION
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The results of this study showed that compared with control subjects, test subjects chewed the dried apricot and fresh white bread at a significantly slower rate. After denture adhesive was applied, the chewing rate increased significantly and approached that of the control subjects. Mandibular movements during chewing were irregular for 60 percent of the test subjects. After denture adhesive was applied, both denture movement and mandibular movement irregularities were reduced.
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FOOTNOTES
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Drs. Baker and Winston are employees of Procter & Gamble Co., which markets Fixodent denture adhesive cream, the denture adhesive cream used in this study.
This research was supported by Procter & Gamble Co.
The authors acknowledge the contributions of Jeff Finkeldey, Susan Knippenberg and Xiaojie Zhou to this article.
Ms. Rendell now is a health care advocate, The Connecticut Department of Children and Families, Hartford. When this article was written, she was a research assistant, School of Dental Medicine, University of Connecticut Health Center, Farmington.
Dr. Gay is a professor emeritus, School of Dental Medicine, University of Connecticut Health Center, Farmington.
Dr. Grassois a professor and an associate dean, Clinical Affairs, School of Dental Medicine, University of Connecticut Health Center, Farmington.
Mr. Baker is a section head, Department of Biometrics and Statistical Sciences, The Procter & Gamble Co., Cincinnati.
Dr. Winston is a senior research scientist, Regulatory and Clinical Development, The Procter & Gamble Co., Health Care Research Center, 8700 Mason-Montgomery Road, Mason, Ohio 45040, e-mail "winstonjl{at}pg.com". Address reprint requests to Dr. Winston.
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REFERENCES
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ABSTRACT
MATERIALS AND METHODS
