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Rehabilitation of edentulous patients remains one of the most challenging treatment modalities. Successful treatment with conventional complete dentures depends to a great extent on patients’ ability to use the denture. The problem is how to identify, through oral examination, which patients exhibit suitable conditions for denture use.1 Several studies have failed to show strong correlations between either patient satisfaction with their dentures and their quality or denture satisfaction and the quality of the denture-supporting tissues.2,3
The insertion of new dentures greatly impacts the stomatognathic system. Changes may take place in chewing, speech, tasting, swallowing, salivary flow, and esthetics. A period of 6 to 8 weeks has been regarded as necessary to assess satisfactory use with the new dentures, as this period has the potential to establish new memory patterns for the masticatory muscles.4 In a previous study, although approximately 60% of experienced denture wearers were able to eat and speak satisfactorily within a week after replacement dentures were fitted, another 20% of these patients required up to 1 month to become proficient.5 Occasionally, edentulous patients go without dentures for long periods and experience increased difficulty in learning to masticate with new dentures, and the time for adjustment will likely be extended.6
Although most edentulous patients appear to benefit from complete denture treatment and report satisfactory oral and masticatory function with their use,7 a minority of patients seems to never adapt to any conventional complete denture.8 In these cases, significant increase in patient satisfaction and oral health–related quality of life may be observed with implant-retained dentures.9 Improvement in masticatory function has been given as the most common reason for choosing dental implant prosthesis, and 82% of patients reported improved subjective chewing experience after implant treatment.10
Since adaptation to new conventional dentures is highly variable, it is not known how long dissatisfied patients should wait before opting for a treatment with dental implants. Therefore, the purpose of this study was to investigate whether changes in patient satisfaction and masticatory efficiency may be observed between 3 and 6 months after the insertion of new conventional complete dentures. The research hypothesis is that a period of 6 to 8 weeks may not be sufficient to achieve optimal use, but further improvements in denture adaptation may be observed for up to 6 months.
Materials and Methods
Study Design, Sampling Procedures, Study Subjects, and Ethical Considerations
The sample used for the present study derived from a previous crossover trial that compared bilateral balanced and canine-guided dentures.11 In that study, patients were divided into two groups with different treatment sequences to avoid bias. Since no difference was found between occlusal concepts,11 data were coupled and analyzed in the present study for changes in masticatory efficiency and patient satisfaction after the insertion of new dentures.
The study was approved by the Research Ethics Committee of the institution (Protocol # 001/08). Edentulous patients visiting the Clinic of Prosthodontics at Federal University of Rio Grande do Norte, Natal, Brazil and requiring new conventional complete dentures were invited to participate in this follow-up study. After a preliminary examination, patients were excluded if they exhibited symptoms of temporomandibular disorders, xerostomia, orofacial motor disorders, severe oral manifestations of systematic diseases, or psychological or psychiatric conditions that could influence their response to treatment. The sample was composed of 24 patients with a mean age of 59.7 years. All patients were diagnosed as Class II (Prosthodontic Diagnostic Index)12 and had previously worn conventional complete dentures. At 3 and 6 months post-insertion, data were collected regarding patient satisfaction and masticatory efficiency.
The dentures were fabricated in accordance with traditional techniques and in cooperation with the undergraduate dental students. Preliminary impressions were made using stock edentulous trays (Tecnodent, www.tecnodent.com) and irreversible hydrocolloid impression material (Jeltrate®, DENTSPLY, www.jeltrate.com). The final impression for the complete dentures was taken with a custom tray, with border-molded impression compound (Impression Compound, Kerr Dental, www.kerrdental.com), followed by a zinc oxide/eugenol impression (Horus, DENTSPLY, www.dentsply.com). Master casts were mounted on a semi-adjustable articulator with a common arbitrary ear–facebow instrument. Dentures were made in centric occlusion and anatomically shaped acrylic teeth with a cuspal inclination of 33º (Trubyte Biotone, DENTSPLY).
A validated method for quantifying overall satisfaction of complete denture wearers was used. Subjects were asked to respond to questions with three-grade answers (well satisfied, satisfied, and dissatisfied) concerning 12 factors: chewing, tasting, speech, pain (maxillary and mandibular), esthetics, fit (maxillary and mandibular), retention (maxillary and mandibular), and comfort (maxillary and mandibular). Then, the three grades were turned into scores according to the degree of contribution of each factor as previously established.13
Masticatory Efficiency Test
Masticatory efficiency was performed through the colorimetric method. The beads were the artificial test food used to measure the masticatory efficiency.11 They were obtained by ionotropic jellification of an aqueous dispersion of 2% pectin containing 50% solids and fuchsine dye in a 1.0 M calcium chloride solution. After preparation, the beads were coated with a 5% Eudragite solution (Eudragit® E100, Evonik Industries, http://eudragit.evonik.com) in a solvent mixture of 10% acetone in absolute ethanol. Then, 250 mg of the beads were packed in polyvinyl acetate capsules in a rectangular 0.70-inch x 0.51-inch form and sealed.
For application of the masticatory test, subjects seated on a chair with a back and with both feet resting on the ground were asked to chew the beads in their habitual manner, without being given any additional instruction on how to chew, in an effort to best replicate habitual mastication. The test was stopped after 20 seconds, and the beads were collected into a container identified by subject and test number. This test was repeated two more times. In no case was the polyvinyl acetate capsule shell damaged, so no beads’ interiors were allowed to escape.
After chewing, the capsule shell was cut and the content of the beads was placed in a 20-ml test tube, dissolved in 5 ml of distilled water, and shaken mechanically in a rotary shaker (Certomat® MV, B. Braun Biotech International, USA, www.bostonlabco.com) for 30 seconds. The solution was then filtered through qualitative filter paper, and the extracted dye was quantified in nanometers (nm) with a Beckman DU-640 UV-Visible Spectrophotometer (Ultrospec 2100 pro UV/Visible Spectrophotometer®, GE Healthcare, USA, www3.gehealthcare.com). It allowed the measurement of masticatory efficiency on the basis of the concentration of extracted fuchsine, which was expressed in absorbance (abs).
Data were collected by a single examiner to avoid interexaminer variability. The masticatory efficiency of each subject was calculated as the mean value for the three tests. The reliability of the masticatory test was analyzed by one-way ANOVA with Tukey test as post-hoc test (P < 0.05). Data were processed with SPSS software (V 17.0 for Windows, SPSS Inc., www-01.ibm.com). Differences regarding patient satisfaction and masticatory efficiency between 3 and 6 months post-insertion were compared using the paired-samples t test. Shapiro-Wilk and Levene tests were used to observe normality and variance homogeneity, respectively. Confidence level was set at 95%.
Data for masticatory efficiency and patient overall satisfaction are presented in Table 1. No difference for patient overall satisfaction and masticatory efficiency between 3 and 6 months after the insertion of new dentures was observed. Table 2 presents the data for the 12 factors that contributed to patient overall satisfaction. Significant differences for mandibular pain (P < 0.05) and mandibular fit (P < 0.05) were observed (P < 0.05).
The results of this study support the research hypothesis that a period of 6 to 8 weeks may not be sufficient to achieve optimal use with new conventional dentures. Further improvements in denture adaptation were observed for up to 6 months. It is supposed that dissatisfied patients should take into account this period of adaptation before opting for a treatment with dental implants. In the present study, dentures were delivered and weekly appointments were scheduled during the first month for clinical adjustments. After that, patients returned at 3 and 6 months for clinical examination and data collection, but no adjustments were made. During clinical examination at 3 and 6 months, neither ulcers nor sore points were found. Interestingly, greater satisfaction relative to mandibular pain and mandibular fit were observed at 6 months (P < 0.05). Data were collected only at 3 (baseline) and 6 months post-insertion to avoid the influence of the initial period of adaptation and clinical adjustments and the improvement in patient satisfaction that is to be expected during this period.
The results of this study suggest that some patients may take up to 6 months to achieve optimal use with their new mandibular dentures. It is hypothesized that the improvements in pain and fit observed in this study may be related to changes that may occur slowly in the mandibular residual ridge (bone remodeling) and mucosal covering to adapt to the intaglio surface of the new dentures. Also, it is hypothesized that patients may assume that some degree of discomfort is to be expected in their situation, so they complain less during the time period. The period of 6 to 8 weeks regarded as necessary to establish new muscle memory patterns is probably related to the domains of mastication, speech, and retention, which did not present any change during this study. Actually, there is no consensus about the amount of time that dissatisfied denture wearers should wait before choosing a treatment with dental implants.
Despite increased satisfaction for reduced mandibular pain and improved mandibular fit at 6 months, no difference was found for patient overall satisfaction. This is probably related to the methodology used. In the present study, patients were asked to respond to questions with three-grade answers (well satisfied, satisfied, and dissatisfied) concerning 12 denture factors. Then, the three grades were turned into scores according to the degree of contribution of each factor as previously established by Sato et al.13 The contribution of each grade of the 12 factors to the overall satisfaction was determined by multiple regression analysis, and seven factors were found to be highly correlated with the overall satisfaction (chewing, speech, maxillary pain, esthetics, maxillary fit, mandibular retention, and maxillary comfort). Based on the level of contribution by these seven significant factors, which did not include mandibular pain and mandibular fit, patient overall satisfaction was calculated.
It has been shown that patients usually complain less about comfort and retention of the maxillary than of the mandibular denture.8 The results of this study are in agreement with that, since improvements in pain and fit were limited to the mandibular denture. It is supposed that immediate satisfaction with new dentures is lower for the mandible due to its anatomical characteristics, and patients need more time to adapt to mandibular than to maxillary dentures. A previous study investigated how patients’ ratings of their prosthesis changed over time.12 Patients were asked to rate their dentures in varying domains at insertion, 3 months, and 2 years. Chewing ability and comfort of the mandibular denture increased over time. According to the authors, habituation to dentures may continue over 2 years to overcome gradual deterioration of denture quality that might reasonably be expected over 2 years after denture insertion.14
No difference was found for masticatory efficiency and patient satisfaction regarding chewing ability, tasting, speech, esthetics, retention, and comfort. These results suggest the reestablishment of these domains at 3 months post-insertion of new dentures. The muscles of the tongue, cheeks, and lips must be trained to retain the dentures in position on the residual ridges during mastication.6 According to Zarb and Bolender,4 6 to 8 weeks are necessary to establish new memory patterns for the muscles of mastication. In addition, salivary excess may impair comfort and make chewing and speech difficult during the initial period of denture wearing.4 Speech may also be influenced by tongue positioning necessary to stabilize the lower denture.4 Taste sensitivity may be reduced when an upper denture covers the hard palate due to the fact that a smooth acrylic denture surface may modify the sense of touch within the oral cavity.6 Finally, patients must understand that their appearance with new dentures will become more natural with time. A repositioning of the oral and facial muscles and a restoration of the former facial dimension and contour by the new dentures may seem like too great a change in the patient’s appearance.6
In the present study, the masticatory efficiency was measured with the beads.11 In this method, the test material is promptly evaluated and has stable physical properties. Since the beads are packed in the capsules, the material is fully obtained from the mouth, with no danger of being swallowed nor dissolved by saliva. Laboratory processing is fast and effective and allows precise determination of the patient’s masticatory efficiency. The capsules are not torn or ripped during mastication, and thus the granules are kept inside the capsule. All granule components are listed in the Brazilian pharmacopoeia and can be reproduced.
To summarize, the results of this study showed that further improvements in pain and fit of the mandibular denture may be observed between 3 and 6 months after the insertion of new dentures. While a period of 6 to 8 weeks may be sufficient for muscle adaptation and satisfactory control of the new dentures during functional activities,4 some patients may require more time to achieve optimal use with their new mandibular dentures. Actually, there is no consensus about the amount of time patients dissatisfied with their new conventional dentures should wait before choosing a treatment with dental implants. The results of this study suggest that a period of 6 months should be considered. It is crucial that realistic expectations of dentures are created with the patient before treatment is actually started. Patients should be informed that new dentures require a period of adjustment, which is highly variable and depends on their anatomic, psychological, tissue tolerance, and oral conditions.6
Reduction in pain and improvements in fit of the mandibular denture may be observed between 3 and 6 months after the insertion of new conventional complete dentures. This period of adaptation should be considered before choosing a treatment with dental implants.
The authors had no disclosures to report.
About the Authors
Arcelino Farias-Neto, DDS, MSc, PhD
Professor, Health School
Potiguar University – Laureate International Universities,
Adriana da Fonte Porto Carreiro, DDS, MSc, PhD
Department of Dentistry
Federal University of Rio Grande do Norte
Queries to the author regarding this course may be submitted to firstname.lastname@example.org.
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